Untitled

THE JURASSIC SYSTEM 

IN GREAT BRITAIN

Oxford University Press, Ely House, London W. I 

GLASGOW NEW YORK TORONTO MELBOURNE WELLINGTON 

CAPE TOWN SALISBURY IBADAN NAIROBI DAR ES SALAAM LUSAKA ADDIS ABABA 

BOMBAY CALCUTTA MADRAS KARACHI LAHORE DACCA 

KUALA LUMPUR SINGAPORE HONG KONG TOKYO

Photo. W.J. A. 

Portland Beds, West Weare Cliff, Isle of Portland. 

Cliff of Portland Sand and the Cherty Series of the Portland Stone, from the top of which the Freestone Series 

has been quarried. The beginning of Chesil Beach is seen on the left, with Portland Harbour beyond.

THE 

JURASSIC SYSTEM 

IN GREAT BRITAIN 

BY 

W. J. ARKELL 

OXFORD 

AT THE CLARENDON PRESS

'If the elucidation of earth history and the origin and 

evolution of life on the globe are not of prime importance 

as ends in themselves, if the whence and the why and the 

whither are not supreme, then indeed has our lot fallen 

among evil days.' 

E. W. BERRY, I 91 9 

Address before the Geological Society of Washington 

Amer. Journ. Sci., vol. xlviii, p. 11. 

FIRST PUBLISHED 1933 

REPRINTED LITHOGRAPHICALLY IN GREAT BRITAIN 

AT THE UNIVERSITY PRESS, OXFORD 

BY VIVIAN RIDLER 

PRINTER TO THE UNIVERSITY 

1970

PREFACE 

IN England, in the sphere of Jurassic geology, we are wardens of a classic 

area, for our cliffs and quarries are the standards of comparison for the 

whole world. A German authority, Dr. Hans Salfeld, remarked after a brief 

study in 1914: 'Research on the faunas and their succession shows that the 

English Upper Jurassic can be taken as the type of that of North-West Europe, 

in the most complete development anywhere yet known.' He had studied only 

the Upper Jurassic, but the same could with equal truth be said of the Lower. 

This is no mean heritage. In our Jurassic rocks all the principles of stratigraphy 

are illustrated perhaps more clearly than in any other part of the 

geological record. Palaeontologically, too, the system contains an unequalled 

wealth of materials; and for the evolutionist, the ecologist and the palaeogeographer 

no more favourable field exists. 

The aim of this book is, first and foremost, to provide a general description 

of the Jurassic rocks of the British Isles, indicating what work has been done 

and where the information is to be obtained, and to illustrate some of the 

magnificent type-sections. It has been found that to give even an outline 

account of the rocks and the various changes that they undergo as they are 

traced across the country, pointing out the presence and significance of discordances, 

and arranging the facts in sequence as data for the elucidation of 

earth-history, is a matter of considerable difficulty within the limits of one 

volume. 

Although such gigantic compilations as The Jurassic Rocks of Britain (in 

5 volumes, although Scotland and Ireland are not included) have long remained 

invaluable sources of facts for those who knew how to interpret the 

information they contain in the light of subsequent discoveries, it is hardly 

likely that they will be repeated or brought up to date. They labour under a 

fundamental disability, for by striving after an illusory completeness they 

become more and more encumbered with detail as new discoveries are made 

—a negation of progress. Unless the endless description of sections and 

listing of fossils be regarded as a worthy aim in itself, it will be agreed that the 

discovery of new exposures, the filling in of gaps, should lead to the elimination 

of detail and enable generalizations to be made. 

I have not attempted, therefore, to compile a summary of everything 

known to date concerning the Jurassic System, or to write a handbook suitable 

for taking into the field, with descriptions of quarries for the illustration of 

local geology. It is assumed that any one who wishes to ascertain the exact 

succession displayed at any particular exposure will consult one of the many 

excellent Sheet or District Memoirs of the Geological Survey, or the detailed 

papers cited in the bibliography and footnotes. 

The difficulties experienced, especially by foreigners, in extracting any 

coherent story from the existing literature of the Jurassic System are illustrated 

by several authoritative treatises on stratigraphy that have been published on 

the Continent in the last twenty or thirty years. Haug's Traite de Geologie and 

the equally comprehensive work with the same title by De Lapparent contain 

perhaps the most complete reviews of the Jurassic System yet written; and

vi PREFACE 

although both are twenty years out of date and familiarize the reader with 

classifications and terminologies that have been superseded, they still remain 

the best introductions to the subject extant. But when the British Isles are 

considered, the statements are not twenty but forty years out of date. The 

reader might think that the type-localities of the Lias, the Bathonian, the 

Oxfordian, the Kimeridgian, the Portlandian and the Purbeckian—names 

used the world over—were in a little-known land unfrequented by geologists. 1 

For this we, or at least our predecessors, are largely to blame. It is unreasonable 

to expect a foreigner to search through scores of back numbers of 

the journals of country field-clubs, unknown to him and virtually inaccessible; 

or to read the exhausting reports of innumerable excursions, in which, among 

accounts of the weather and the tea, so many conclusions are interred. And if 

the specialist, as has been proved, will not undertake this work even though he 

have a definite object in view, how much less will the student do so, when he 

can make his choice from many attractive sciences ? 

I think, therefore, that the need for some co-ordinating work will hardly be 

questioned; but any such attempt as this is so largely dependent on the personal 

factor of selection that it is too much to hope that the result will find 

favour with all. Nevertheless, I take heart from the thought that if a score of 

geologists were to make their own selections of relevant facts, there would be 

as many differences of opinion. 

One or two points need explanation. I have striven hard to avo* J unevenness 

of treatment in the Stratigraphical Part, but am aware of having failed 

to eliminate it altogether. A good deal of unevenness, however, is independent 

of the writer and reflects inconsistencies in our knowledge. Some formations 

are much better known than others and are likely long to remain so; yet, 

paradoxically, it is not these that require the most space in description: 

rather it is the formations about which there is still considerable uncertainty 

in some parts of the country, and in which correlations are not alw T ays firmly 

established. The Great Oolite Series and the Corallian Beds, for instance, 

cannot be so readily summed up as the Inferior Oolite. Thanks to the work 

of the late S. S. Buckman and Mr. L. Richardson, the Inferior Oolite Series 

from Dorset to Northamptonshire is so thoroughly known that almost perfect 

generalization is possible: a detailed section of the beds can be drawn right 

across the country. Where there have been no recent revisions, on the other 

hand, it is necessary to give more details and also to document the statements 

more fully. Quite apart from this, it is obvious that the oolites, with their 

numerous transformations of facies, occupy more space in treatment than 

relatively uniform deposits like the Lias. 

A different form of unevenness that is difficult to avoid entirely is geographical. 

The emphasis laid on Dorset, however, is intentional. The description 

1 Haug was able to write so recently as 1911: 'Malgre que les coupes de Tile de Portland 

et des environs de Swanage et de Kimeridge soient classiques, les nombreuses divisions 

locales £tablies par les g£ologues anglais ne permettent guere de parall£lismes precis avec les 

autres regions, car les Cephalopodes sont rares et la plupart des especes que Ton a cities sont 

bashes sur des figures tr&s m£diocres et auraient besoin d'une s£rieuse revision' (Traitey p. 

1081). That the cephalopods were not the only matters about which he was misinformed is 

shown by a statement on the next page, to the effect that in Dorset: 'Le Purbeckien repose en 

discordance sur le Portland Stone et supporte lui-meme en discordance le Wealdien.' Both 

assertions are untrue. Similar instances may be multiplied almost indefinitely when foreign 

literature is consulted.

PREFACE vii 

of every formation has been started from there, using its cliffs as a standard, 

because they undoubtedly show the full marine sequence of the Jurassic 

System incomparably better developed and better exposed than any other 

sections in the British Isles. 

I am conscious of having perhaps dwelt in the first chapter too long for 

some tastes on the stratigraphical and chronological terms in modern use and 

on the refinements of meaning attached to them. But I hope that if these 

terms are unmasked at the outset they will have ceased to trouble the reader 

when he comes across them in the ensuing chapters, and afterwards in other 

works. The terms have their uses in clarifying our conceptions. Moreover, it 

is essential to realize from the beginning that, formidable though they seem at 

first, and fraught with weighty possibilities, they all lead to nothing. Although 

we have built up an imaginary time-scale as a pure abstraction, entirely 

separate from any known sequence of strata at any one place, yet it advances 

us no further towards the measurement of earth history by an absolute chronology; 

for the units are still of unknown and unequal duration, whatever scale 

we employ. Whether we speak of hemeras, of biochrons or of zone-moments, 

is a matter of personal choice or local expediency, but whichever we choose we 

are only, as it were, playing a game, in which we decide beforehand what are 

to be the rules. As if to compensate themselves for their ignorance of the real 

values of their units, geologists have made much of the theoretical differences 

between them and have invented wonderful words to distinguish them. 

One day, perhaps, it may become possible to attach our present chronology 

to an absolute time-scale, measured in fixed, definite units. Either we may 

gain some conception of the average duration in years of ammonite species, 

or we may discover the frequency of the pulse of earth-movements controlling 

the cycles of sedimentation (and so, indirectly, the life-succession). The realization 

of this ideal seems as far off as ever, but meanwhile it is something to 

perfect our shadow-chronology and have it ready, awaiting the time when the 

key will be supplied to interpret its relative conceptions in absolute terms. 

Any value this book may have is largely due to the help I have received from 

a number of kind friends. First and foremost I am indebted to Prof. W. J. 

Sollas, F.R.S., in whose department the work has been done, and on whose 

students much of the matter has been tried out in lectures. He and Mr. L. 

Richardson, F.R.S.E., Prof. A. E. Trueman, Prof. A. Morley Davies, 

Dr. R. H. Rastall, Dr. J. A. Douglas, Dr. F. L. Kitchin, F.R.S., and Dr. J. 

Pringle, have very kindly read through one or more chapters in manuscript or 

typescript and have made valuable comments and corrections. How much 

the stratigraphical part owes to conversations and correspondence with 

Mr. Richardson, I cannot attempt to assess. I will only say that without his 

interest and collaboration in certain researches in the field it would have been 

impossible to write the chapters on the Inferior Oolite and Great Oolite in a 

form presentable for publication. He has also given me reprints of many 

papers and put at my disposal his collections and the manuscript of his 

recently published revision of the Inferior Oolite of the Sherborne district. 

To Dr. J. Pringle I am also indebted for his help in replying to inquiries on 

various points and for kind gifts of rare papers; and to Dr. L. F. Spath for 

much information imparted in the course of discussions on the ammonites.

viii PREFACE 

Professor P. F. Kendall, F.R.S., generously lent me some of his note-books; 

Dr. R. H. Rastall put at my disposal the results of his work on the heavy 

minerals of the Yorkshire Estuarine Series; Dr. Vernon Wilson kindly helped 

with the Yorkshire Corallian, and Mr. Malcolm MacGregor with the rocks of 

Northern Trotternish. 

To the skilful collaboration of Mr. J. W. Tutcher is largely due the series of 

plates at the end of the volume, illustrating the zonal species of ammonites. It 

was my own experience to be familiar for years with the names of some of the 

zonal ammonites, which appear in every paper and memoir, before being 

able to discover to what the names actually applied. The lack of figures of 

even the most commonly quoted species is astonishing. It was therefore my 

intention to figure all the principal species, from either the type-specimens or 

properly authenticated material, or, failing both, from the protographs; and 

to this end Mr. Tutcher readily consented to collaborate. Since the zonal 

indices are frequently foreign and are by no means always abundant in this 

country, even when the proper zones are developed, absolute authenticity 

cannot be claimed for every species figured; but it is believed that most of 

the identifications are close enough to fall within the range of individual variation. 

Mr. Tutcher has been almost entirely responsible for selecting the specimens 

from the Lias and Inferior Oolite, and nearly all of them are from his 

own collection; for the higher formations I have been mainly responsible. 

Where the exact identification of a species is notoriously a matter of controversy 

(as with the Perisphinctids of the Corallian) I have thought it better to refigure 

the type-specimens, even though they may provide indifferent material, and 

thus to make the characters of the types more familiar, rather than to risk 

adding to the confusion by publishing yet another mis-identification. It is 

to be regretted that the figures of some of the species are of necessity greatly 

reduced in size, but it was considered better to give a reduced figure of the 

larger ammonites than none at all. The amount of the reduction and the 

dimensions of the original are always stated. For the loan of specimens or 

the gift of casts, photographs and advice, I am indebted to Dr. F. L. Kitchin, 

Dr. W. D. Lang, Dr. L. F. Spath, and Prof. A. Morley Davies. 

For permission to reproduce or use drawings or photographs from their 

works throughout the book, my thanks are due to Prof. A. E. Trueman, 

Mr. J. W. Tutcher, Dr. R. H. Rastall, Mr. L. Richardson, Prof. P. F. Kendall, 

Dr. F. A. Bather, Dr. R. Brinkmann, Dr. E. Neaverson, Mr. M. Black, 

Prof. S. H. Reynolds and Prof. A. Morley Davies (who has also kindly 

supplied a revised map of the outcrop of the Arngrove Stone); for further 

permission to make use of figures I am indebted to Prof. A. Gilligan (for 

allowing me to select some photographs from the Godfrey Bingley Collection), 

to Mrs. Buckman, and to the Councils of the Royal Society, the 

Geological Society of London, the Geologists' Association, the Palaeontographical 

Society, and the Yorkshire Geological Society, the Director of the 

Geological Survey, and the Controller of H.M. Stationery Office. 

Finally, the unfailing courtesy and patience shown by all at the Clarendon 

Press have made the production of this book a pleasure. 

W. J. A. 

OXFORD, January 1933.

CONTENTS 

PART I 

CLASSIFICATION AND CHRONOLOGY 

CHAPTER I. THE CLASSIFICATION OF THE ENGLISH JURASSIC ROCKS AND THE PARTI- 

TION OF JURASSIC TIME I 

PART II 

DISTRIBUTION AND TECTONICS 

CHAPTER 11. THE GENERAL STRUCTURE OF THE TROUGHS OF DEPOSITION . . 39 

CHAPTER 111. CONTEMPORANEOUS TECTONICS AND THEIR EFFECTS ON SEDIMENTA- 

TION 51 

PART III 

STRATIGRAPHY 

LOWER JURASSIC OR LIAS 

CHAPTER IV. RH^TIC BEDS 97 

CHAPTER V. LOWER LIAS 117 

CHAPTER VI. MIDDLE LIAS 153 

CHAPTER VN. UPPER LIAS 165 

MIDDLE JURASSIC: LOWER OOLITES OR DOGGER 

CHAPTER VM. LOWER AND MIDDLE INFERIOR OOLITE . . . .189 

CHAPTER IX. UPPER INFERIOR OOLITE . 230 

CHAPTER X. GREAT OOLITE SERIES . 248 

CHAPTER XI. CORNBRASH . 326 

UPPER JURASSIC: MIDDLE AND UPPER OOLITES OR MALM 

CHAPTER XII. OXFORD CLAY AND KELLAWAYS BEDS 340 

CHAPTER XIN. CORALLIAN BEDS 376 

CHAPTER XIV. KIMERIDGE CLAY 440 

CHAPTER XV. PORTLAND BEDS 481 

CHAPTER XVI. PURBECK BEDS 518 

CHAPTER XVN. THE TRANSITION TO THE CRETACEOUS 540 

PART IV 

PALAEOGEOGRAPHY 

CHAPTER XVIII. PALAEOGEOGRAPHICAL CONCLUSIONS . . . 557 

ILLUSTRATIONS OF ZONAL INDEX FOSSILS . . . . .601 

APPENDIX 1. CORAL REEFS, GEOSYNCLINES, PENEPLAINS . . . 615 

APPENDIX 11. LIST OF STAGES . . . . . . . .617 

BIBLIOGRAPHY 623 

INDEX . . . . . . . . . . . . 671 

CORRIGENDA . . . . . . . . . . .681

LIST OF PLATES 

West Weare Cliff, Isle of Portland . . . . 

i. Cliffs of Blue and White Lias, Pinhay Bay, Lyme Regis . 

II. Garden Cliff, Westbury on Severn, Gloucestershire 

in. Black Ven, Stonebarrow Cliff, and Golden Cap from Lyme Regis 

Charmouth and Stonebarrow Cliff from Church Cliffs, Lyme Regis 

iv. Frodingham Ironstone Workings, near Scunthorpe, Lincolnshire 

Blue Lias cliffs west of Lyme Regis 

v. Golden Cap (619 ft.) from Seatown, Dorset 

Down Cliff and Thorncombe Beacon from Eypesmouth . 

vi. Cliff of Bridport Sand capped with Inferior Oolite, West Bay 

Bridport Harbour . . . . . 

Golden Cap and Thorncombe Beacon from Burton Bradstock 

VII. Cliffs of Whitbian Shales and Middle Lias, Hawsker Bottom 

Whitby . . . . . . 

Cliffs of Bridport Sands near Burton Bradstock . 

VIII. Inferior Oolite at Leckhampton Hill, near Cheltenham 

ix. Inferior Oolite at Leckhampton Hill Quarry, Cheltenham . 

Pea Grit Series at Crickley Hill, near Cheltenham 

x. Bearreraig Bay, near Portree, Isle of Skye 

Dun Caan and the east coast of the Isle of Raasay, from Rudha J 

na'Leac . . . . . . . j 

xi. Upper Inferior Oolite overlying Carboniferous Limestone, Eastern 

Mendips . . 

xii. Fuller's Earth and Forest Marble, Watton Cliff, Bridport . 

Fuller's Earth Rock, Shepton Montague railway-cutting, Somerset 

XIII. Great Oolite Series at Kirtlington Cement Works, near Oxford 

Chipping Norton Limestone-equivalents, Fritwell cutting, Oxon. 

xiv. Dun Caan and the east side of the Isle of Raasay . 

Fascally Coal Mine, Brora, Sutherland 

xv. Lower Oxford Clay, Calvert Brickyard, Buckinghamshire . 

xvi. Osmington Oolite Series, east of Osmington Mills, Dorset 

xvn. Corallian Beds at Redcliff, near Weymouth, Dorset 

xviii. Gristhorpe Cliff and Carr Naze, near Filey, Yorkshire 

xix. Hounstout Cliff, Dorset . . . . . 

xx. Hen Cliff, Kimeridge . . . . . 

Kimeridge Bay from The Flats . . . . 

xxi. Ringstead Bay and White Nothe Head 

Junction of Kimeridge Clay and Corallian Beds, Ringstead Bay 

XXII. THE 'FALLEN STACK', PORTGOWER, NEAR HELMSDALE, SUTHERLAND 

KIMERIDGIAN BOULDER BED, PORTGOWER, SUTHERLAND . . / 

XXNI. PORTLAND BEDS AT WINSPIT QUARRY, NEAR WORTH MATRAVERS, DORSET \ 

PORTLAND AND PURBECK BEDS, DANCING LEDGE QUARRY, LANGTON} 

MATRAVERS, DORSET . . . . . .) 

XXIV. SWYRE HEAD, HOUNSTOUT CLIFF AND EMMIT HILL, FROM ST. ALBAN'S I 

HEAD . . . . . . . ./ 

xxv. West Weare Cliff, Portland . . . . 

Portland and Purbeck Beds, Gad Cliff, Dorset 

xxvi. Titanites and silicified tree-trunks from the Portland Dirt Bed 

xxvii. Purbeck Beds, Bacon Hole and Mupe Rocks, Dorset 

The Fossil Forest, Lulworth, Dorset 

xxvi 11. Durdle Door, near Lulworth . . . . 

Vertical Purbeck Beds, Durdle Cove, Lulworth 

xxix. Characteristic lamellibranchs of the Rhsetic and Pre-platiorbis Beds 

xxx. Zonal ammonites of the Lower Lias 

xxxi. „ „ „ Lower and Middle Lias . 

Frontispiece 

Facing p. 98 

99 

120

xii LIST OF PLATES 

XXXII. Zonal ammonites of the Upper Lias 

xxxin. ,, ,, ,» Lower and Middle Inferior Oolite 

xxxiv. 

Middle and Upper Inferior Oolite 

xxxv. 

Great Oolite Series and Cornbrash 

xxxvi. 

Kellaways Beds and Lower Oxford Clay 

XXXVII. 

Oxford Clay 

XXXVIII. 

Corallian Beds 

XXXIX. 

Kimeridge Clay . 

XL. 

XLI. Zonal ostracods of the Purbeck Beds 

Upper Kimeridge and Portland Beds 

Figures 15, 30, 35 are folders facing pages 84, 165, 197 respectively. 

At end

PART I 

CLASSIFICATION AND CHRONOLOGY 

CHAPTER I 

THE CLASSIFICATION OF THE ENGLISH JURASSIC 

ROCKS, AND THE PARTITION OF JURASSIC TIME 

'England, by reason of the simple stratigraphical relations of its beds, the usually 

marked lithological peculiarities of each individual member of the series, and the 

extraordinary wealth of its fossil remains, became the classic ground of the Jurassic 

System. Thus the classification of the British Jurassic strata, laid down by William 

Smith and but little modified by Conybeare, Phillips, Buckland and de la Beche, 

supplied the names under which geologists have endeavoured to range the contemporaneous 

formations all over the world/ 

K. von Zittel, 1899, Geschichte der Geologie und Palaontologie, p. 659. 

IN the early stages of the inception of this book it was proposed to translate 

all our haphazard terms, such as Inferior Oolite and Corallian Beds, into the 

properly systematized stage-names used on the Continent—Bajocian, Bathonian, 

Argovian and the rest. But the difficulties soon began to pile up to such 

an extent that they formed a mountain of polemical matter barring further 

progress: the objects of the book began to be in danger of being lost sight 

of amid the monstrous and sterile problems of stratigraphical nomenclature. 

These problems have obstructed geologists for a century and they can only 

be solved by an international committee with dictatorial powers, similar to 

that which has in some measure introduced order into the nomenclature of 

zoology. My object never was to attempt a solution of these problems singlehanded, 

but to give descriptions and correlations of the Jurassic rocks of the 

British Isles, properly arranged as documents of history, and to draw as many 

historical conclusions from them as possible. The system of classification is 

therefore a secondary consideration, and all that is required of it is efficiency. 

Although many of the systematized stage-names used on the Continent are 

taken from English localities (for example Oxfordian, Kimeridgian) they do 

not correspond even approximately with the strata which English geologists 

have always associated with those names. Directly we begin to apply them to 

the English rocks we are faced with fundamental difficulties. Is such a term as 

Portlandian to be used as if it were synonymous with Portland Beds, or as its 

author, d'Orbigny, used it, to embrace about half of our Kimeridge Clay? 

Is Oxfordian to be applied only to the Corallian Beds and uppermost Oxford 

Clay because it was so used by d'Orbigny, although he was oblivious of the 

fact that he was excluding the bulk of the Oxford Clay from the Oxfordian? 

Or, alternatively, which of the numerous subsequent attempts at adjustment 

are to be accepted ? Once we deviate from the original meanings of the terms 

and abandon the principle of priority, we lose our hold on the only lifeline that 

can save us from the slough of conflicting opinions. 1 

If we are to describe our rocks under names defined according to the 

1 It must be remembered that a rigid application of the rule of priority would invalidate 

nearly all d'Orbigny's stage-names, for most of them had been previously used as stratigraphical 

terms with different meanings. There seems no reason why the addition of -ten or 

ian to a name should justify an author in overriding all previous usages (see p. 13).

IO CLASSIFICATION AND CHRONOLOGY 

development of the strata on the Continent, a close study and revision of the 

foreign rocks must precede any attempt to classify our own. Even were such 

an undertaking possible, or the necessary postponement of work on our own 

rocks desirable, we should often find that when a French or German term had 

at last been thoroughly understood and defined, the development of the strata 

in the place of its origin would be so different from anything we know in 

England as to render the term quite unsuitable and indefinite in our own 

country. The tribulations that beset the English stratigrapher, attempting to 

use d'Orbigny's stage-names conscientiously, resemble those of a Chinese 

historian struggling to marshal his dynasties into such vague and exotic 

periods as The Renaissance, The Perpendicular, The Hyksos, or The Pre- 

Raphaelite. 

When geologists of every nation have studied, described and redescribed the 

succession of rocks, and above all of the fossil faunas, in their own countries, 

bringing their correlations up to date with the advances of the sole international 

medium, palaeontology, only then will the time be ripe for standardizing 

stratigraphical nomenclature. Meanwhile each country must use 

its own terminology, evolved to suit its own particular circumstances. The 

multiplication of local names is no evil, for no one need learn them all. On 

the other hand, the more detailed they are, the more accurately will they 

enable foreigners to comprehend the palaeontological succession, on which 

alone correlations can be made, and which must eventually form the basis of 

any international classification. 

We need not, therefore, despise our own indigenous terminology in speaking 

or writing of the English rocks. Apart from the advantage of their perfectly 

definite meaning, the names by which the Jurassic formations in England have 

been known for so long are worthy to be preserved because they are the 

earliest terms ever used in stratigraphical geology. They embody the first 

beginnings of the science, and most of them are a direct heritage from its 

originator, William Smith. Sir Archibald Geikie wrote in 1897: 

'The growth of stratigraphical nomenclature is eminently characteristic of the 

early rise and progress of the study of stratigraphy in Europe. Precisians decry this 

inartificial and haphazard language, and would like to introduce a brand new harmonious 

and systematised terminology. But the present arrangement has its 

historical interest and value, and so long as it is convenient and intelligible, I do not 

see that any advantage to science would accrue from its abolition. The method of 

naming formations or groups of strata after the districts where they are typically 

developed has long been in use and has many advantages, but it has not supplanted 

all the original names, and I for my part hope that it never will / 1 

I. WILLIAM SMITH AND THE STRATAL TERMS 

As the history of the familiar names Cornbrash, Great Oolite and the rest 

is closely bound up with the history of William Smith and the development of 

his fundamental theory of the constant order of superposition of the strata 

and the possibility of recognizing them by means of their organic contents, it 

is of no small interest to trace the origin of what Adam Sedgwick called 'those 

arbitrary and somewhat uncouth terms w r hich we derive from him as our 

master'. 2 

1 A. Geikie, 1897, The Founders of Geology, p. 244. 

2 Adam Sedgwick, Address to the Geological Society at the presentation of the first 

Wollaston Medal to William Smith, Feb. 18th, 1831.

WILLIAM SMITH 3 

A manuscript note of William Smith's, dated 'Scarborough, May 17,1839', 

throws interesting light on their origins. 1 

'For several years after the foundation of the earth's history was securely laid', he 

wrote in reminiscence, 'we had no words for the science, no language in which we 

could convey our ideas; its present comprehensive name of Geology remained unnoticed 

in dictionaries and unuttered in England, and usage had scarcely settled 

whether the word strata should not have an s appended; but how numerous are 

now the words from the dead languages which geology has revived and brought 

into common use all over the world! 

'Much doubt remained for a long time whether the science, like chemistry, should 

not have a language of its own; and I, so very incompetent to the task, thought much 

about a new nomenclature, and have been at different times strongly urged to it by 

deep-learned men; but having dictated, off-hand, in the plain language of the 

country, a tabular view of the science to my two first pupils, the Rev. Benjamin 

Richardson and the Rev. Joseph Townsend, that crude manuscript, without any 

revision whatever, was faithfully transcribed from one to another, and soon despatched 

to remote parts of the world. 

'The new cultivators of the science found, as I had done, the necessity of accommodating 

their language to those in the country from whom they had to collect the 

facts; and so, in transmitting by the press the knowledge acquired, some old Saxon 

and British words have been brought into use. . . .' 2 

The crude manuscript referred to was the first stratigraphical table, a 'Table 

of the Order of Strata and their embedded Organic Remains in the vicinity 

of Bath, examined and proved prior to 1799'. It was designed to accompany 

the first geological map ever made, showing the country within a radius of five 

miles round Bath. Both were presented to the Geological Society of London, 

by whom they are still preserved in Burlington House 3 (see p. 4, col. 1). 

The story of how this table came to be drawn up has been interestingly told 

by William Smith's nephew, John Phillips, who wrote the Memoirs of his 

illustrious uncle. 

During the years 1794-9, when Smith was living near Bath as resident 

engineer of a branch of the Kennet and Avon Canal, and was compiling this 

first geological map, he made the acquaintance of an enthusiastic collector of 

fossils, the Rev. Benjamin Richardson of Farleigh Hungerford. 

'The result of a meeting between two such reciprocally adjusted minds was an 

electric combination; the fossils which the one possessed were marshalled in the 

order of strata by the other, until all found their appropriate places, and the arrangement 

of the cabinet became a true copy of nature. 

1 Printed in Phillips's Memoirs of William Smith, 1844, pp. 72-3. 

2 For instance: marl, clunch, lias, brash. Martin Lister used the words clunch, marie and 

Fuller's Earth as early as 1683, but only as types of clay in general. 

3 This can be truly said to be the first geological map, in which colours were used to denote 

strata as distinct from mere soils, and to show their order of superposition. Claims have been 

made for several others: Zittel asserts that the first coloured geological maps were those of 

Gottlieb G laser (Leipzig, 1775) and Wilhelm von Charpentier (Chur-Saxony, 1778), (Zittel, 

History of Geology and Palaeontology, English ed., 1901, p. 38), but these are only soil-maps or 

agriculture maps, of the kind suggested by Martin Lister as early as 1683 ('An Ingenious 

Proposal for a new Sort of Maps . . .', Phil. Trans. Royal Soc., 1684, vol. xiv, No. 164, pp. 

739-46). Of the same kind are the county survey maps published by the Board of Agriculture 

in 1794, 1796 and subsequent years, of which Conybeare and Phillips uphold the priority in 

their Geology of England and Wales (1822, p. xlv). Mr. T. Sheppard remarks that, although 

these may have suggested to William Smith his system of colouring, they give no indication 

of stratigraphical structure ('William Smith: his Maps and Memoirs', 1915, Proc. Yorks. 

Geol. Soc.t N.S., vol. xix, pp. 100-1). 

B 

«:> 4371

Smith's MS. Table 1799 

(unpublished). 

TABLE I.—COMPARISON OF THE EARLIEST TABLES OF STRATA (JURASSIC PORTIONS) 

Smith's'MS. Map Table, 

1812 (unpublished). 

Purbeck Stone, Kentish 

Rag 

Limestones of the Vales 

of (Pickering and) 

Aylesbury 

(Iron Sand and Carstone) 

[misplaced; Cretaceous] 

Townsend's 

Table 1813. 

Smith's Improved 

Table 1815-16. | 

? Superior Oolite 9. Portland Rock 

10. Sand 

Calcareous Grit 

Coral Rag 

Buckland's 

Table 1818. Divisions now used. 

Purbeck Beds PURBECK BEDS 

Portland Stone 

PORTLAND 

Limestone 

BEDS Sand 

11. Oaktree Clay Kimmeridge Clay 

(from Webster, 1816) KIMERIDGE CLAY 

12. 

13- 

Coral Rag and 

Pisolite 

Sand 

3- Clay Dark blue shale 14. Clunch Clay and 

Shale 

Upper or Oxford Oolite, 

Coral Rag 

Calcareous Grit 

CORALLIAN ( 

BEDS 

Oxford, Forest or Fen 

Clay OXFORD CLAY 

Upper CaJc. Grit 

Oolites 

Lower Calc. Grit 

IS- Kelloway's Stone Kelloway Rock KELLAWAYS | Sandstone 

4. Sand and Stone{ 

BEDS 1 Clay 

I Cornbrash 16. Cornbrash Corn Brash CORNBRASH 

5- Clay 

6. Forest Marble 

Forest Marble Rock 

Great Oolite Rock 

Forest Marble 

Great Oolite or Bath I7- 7. Freestone 

Sand and Sand- Forest Marble 

stone [Hinton Sand] Stonesfleld Slate 

Stone 18. Forest Marble Great Oolite 

19. Clay over Upper 

Oolite [Bradford Clay] 

20. Upper Oolite 

GREAT 

OOLITE 

SERIES 

Forest Marble 

j Limestones 

! 1 Stonesfield SI. 

8, 9. Blue and yellow clay 

10. Fuller's Earth 

11. Bastard Fuller's Earth 

Clay 21. Fuller's Earth and Fuller's Earth 

Rock FULLER'S 

EARTH 

Clay 

Rock 

and sundries 

Clay 

12. Freestone Under Oolite Inferior Oolite 22. Under Oolite Inferior or Bastard Oolite 

INFERIOR 

OOLITE 

Upper 

Middle 

SERIES 

Lower 

13. Sand 

( ( 

Sand 23- Sand Sand of Inferior Oolite 

14. Marl, blue! Blue Marl! Blue Clay! 24. Marlstone 

Blue Marl 

25- 

UPPER LIAS 

MIDDLE LIAS 

15. Blue Lias Blue Lias Lyas 26. Blue Lias Lias' LOWER LIAS 

16. White Lias 

17. Marlstone, indigo 

and black marls 

White Lias 27. White Lias 

RIUETIC BEDS

WILLIAM SMITH 5 

'That such fossils had been found in such rocks was immediately acknowledged 

by Mr. Richardson to be true, though the connection had not before presented itself 

to his mind; but when Mr. Smith added the assurance that everywhere throughout 

this district, and to considerable distances around, it was a general law that the 

"same strata were found always in the same order of superposition and contained 

the same peculiar fossils", his friend was both astonished and incredulous.' 

A number of excursions were undertaken, and Smith soon convinced his 

friend of the reality of his discoveries. His first triumph consisted in correctly 

forecasting both the nature of the rock and the contained fossils that would be 

found on the Inferior Oolite outlier of Dundry Hill. 

About this time he also became associated with the Rev. Joseph Townsend, 

a man of letters, and later Rector of Pewsey, Wilts., who accompanied them on 

their geological excursions in the neighbourhood of Bath. 

'One day, after dining together at the house of the Rev. Joseph Townsend/ 

Phillips narrates, 'it was proposed, by one of this triumvirate, that a tabular view 

of the main features of the subject, as it had been expounded by Mr. Smith, and 

verified and enriched by their joint labours, should be drawn up in writing. Richardson 

held the pen and wrote down, from Smith's dictation, the different strata 

according to their order of succession in descending order, commencing with the 

chalk, and numbered, in continuous series, down to the coal, below which the strata 

were not sufficiently determined. 

'To this description of the strata was added, in the proper places, a list of the most 

remarkable fossils which had been gathered in the several layers of rock. The 

names of these fossils were principally supplied by Mr. Richardson, and are such 

as were then, and for a long time afterwards, familiarly employed in the many collections 

near Bath. Of the document thus jointly arranged each person present took 

a copy, under no stipulation as to the use which should be made of it, and accordingly 

it was extensively distributed, and remained for a long period the type and 

authority for the descriptions and order of superposition of the strata near Bath.' 1 

In consequence of this liberality with which Smith shared his ideas with his 

friends, he was anticipated in the publication of all his stratal terms. The Rev. 

Joseph Townsend printed the first list in 1813, at the same time paying a 

handsome tribute to his teacher. 

'To a strong understanding, a retentive memory, indefatigable ardour, and more 

than common sagacity, this extraordinary man unites a perfect contempt for money, 

when compared with science. Had he kept his discoveries to himself, he might have 

accumulated wealth: but with unparalleled disinterestedness of mind, he scorned 

concealment, and made known his discoveries to every one who wished for information. 

' 2 

In the same year, 1813, the list of strata quoted by Townsend was copied in a 

text-book. 3 

This first published list (see p. 4, col. 3) is in some respects more complete 

than the manuscript table of 1799, and partly anticipates the revisions published 

by William Smith with his map of England and Wales in 1815 and in 

the Stratigraphical System of Organised Fossils (1817), but there are serious 

omissions and errors. It will be seen that the manuscript table of 1799 is 

incomplete, for it has a large lacuna between the Clunch or Oxford Clay and 

1 J. Phillips, 1844, Memoirs of William Smith, pp. 28-9. 

2 J. Townsend, The Character of Moses Established for Veracity as an Historian, recording 

events from the Creation to the Deluge, 1813, vol. i, preface. Tables of Strata, pp. 100 et seq. 

3 Bakewell's Introduction to Geology, 1813, p. 259.


the Sand beneath the Chalk (Upper Greensand). William Smith was perfectly 

well aware of the existence of the Corallian Beds, Kimeridge Clay and 

Portland Beds, but his table referred to the country on the road from Bath to 

Warminster, and along this line the strata which he failed to show are wanting, 

for the Gault and Greensand overstep on to the Oxford Clay. The Cornbrash, 

which he added to his revised tables, was probably included in Bed 4, the 

'stone' of the 'sand and stone' above the Forest Marble clay, the sand certainly 

referring to the Hinton Sand (a part of the 'Forest Marble' Series). Townsend 

attempted to make the table more generally applicable by inserting the 

'Superior Oolite' (Portland Stone, see p. 167) and the Coral Rag and [Lower] 

Calcareous Grit, but he placed the last two in inverted relation to one another 

and omitted the Oxford and Kimeridge Clays. Thus, while William Smith's 

table is accurate for the district of which it treats, although incomplete when 

a wider area is considered, Townsend's version, copied by Bakewell, is inaccurate 

and misleading. 

A new point in Townsend's table is the first mention of the term Inferior 

Oolite, in place of the Under Oolite consistently used by Smith. In it also 

appeared for the first time the names Great Oolite or Bath Stone, not figuring 

:n the manuscript table of 1799. 

In the improved tables published by William Smith in 1815 and 1816 

(p. 4, col. 4) the missing strata above the Forest Marble are filled in, the 

Cornbrash, Kellaways Rock (spelled Kelloway's Stone) and other beds being 

enumerated, up to the Portland and Purbeck Stones. Just as some of Smith's 

other words, such as clunch, marl, and brash, were borrowed from agriculture, 

so these last two terms, Portland Stone and Purbeck Stone, were simply 

adopted from the current language of quarrying, building and architectural 

circles. That they were in use at least as early as 1668 is proved from their 

appearance in the Discourses of Dr. Robert Hooke, 1 and they had already 

been adopted in 1811-12 by Thomas Webster. 2 

Webster was a gifted artist and geologist, who came into prominence in 1814 

with a treatise on the Isle of Wight Tertiaries read before the Geological 

Society. In 1811-12 he was sent on a mission to Purbeck by Sir Henry 

Englefield, to study the strata and to compare them with those in the Isle of 

Wight. His series of letters were published in 1816 in Englefield's Description 

of the Principal Picturesque Beauties &c. of the Isle of Wight, accompanied by 

an excellent geological map and accurate drawings. One of the drawings, 

showing the quarrying of the stone at Tilly Whim, where the industry has long 

since died out, is reproduced here (fig. 81, p. 484). In addition to adopting the 

terms Purbeck Beds and Portland Oolite, Webster seems to have been the 

first to use the expression Kimeridge Clay. 3 The Portland Sand, although 

1 Posthumous Works of Robert Hooke, 1705: Lectures and Discourses of Earthquakes and 

Subterraneous Eruptions (delivered 1668), pp. 289, 320. Burford-stone and Northamptonshire-stone 

are also mentioned. This advanced thinker and observer, unlike his contemporaries, 

Robert Plot and Martin Lister, perceived the true nature of fossils, and he figured a number of 

Jurassic and Carboniferous species on admirable plates. From the surmise that "tis not improbable, 

but that many Inland Parts of this Island, if not all. may have been heretofore all 

cover'd with the Sea, and have had Fishes swimming over it' he goes on by a comparison 

between the fossils and their living counterparts to suggest that there have been changes of 

climate produced by alteration in the earth's axis. He was also the first discoverer of vegetable 

cells. 

2 Who was wrongly credited with the first use of them by H. B. Woodward in his Jurassic 

Rocks of Britain. 3 In Englefield's Description . . . of the Isle of Wight, 1816, Plate 47.

WILLIAM BUCKLAND 7 

entered as 'sand' in its proper place in William Smith's table, was not named, 

but received its name later (in 1827) from Fitton. 

It is noticeable that in Smith's revised tables the term Marlstone is for the 

first time used in its present sense, having been previously applied to some 

part of the Rhsetic Beds or Tea Green Marls, between the White Lias and the 

Red (Keuper) Marls. 

The next and last great addition to the table of the Jurassic strata was made 

by Dean Buckland, in 1818, the year before he was elected to the newly 

founded chair of Geology at Oxford, where he already held the Readership in 

Mineralogy. His table 1 (p. 4, col. 5) shows that the scene had now shifted 

from Bath to Oxford, for we have Upper or Oxford Oolite, Oxford, Forest or 

Fen Clay, and Stonesfield Slate. Oxford Clay has survived, while its synonyms, 

descriptive of the kind of country to which it gives rise, have, like Smith's 

earlier term, Clunch Clay, been forgotten. On the other hand Oxford Oolite, 

which is in many ways preferable to Corallian or Coralline Oolite, has in spite 

of its priority and legitimate form been discarded, although Buckland mentioned 

as typical localities Headington (Oxon.), Calne (Wilts.) and New 

Malton (Yorks.). He described it as 'perishable freestone, composed of oolitic 

concretions and shelly fragments, united by a calcareous cement, with a 

waterworn surface at Headington'; clearly, therefore, he meant it to apply to 

the detrital or 'Wheatley Limestones' facies of the Osmington Oolite Series 

(see p. 405). We now know that the Coral Rag around Oxford, which he placed 

below the Oxford Oolite, is in reality contemporaneous with it, and Oxford 

Oolite therefore has prior claim to be the name used for the Osmington Oolite 

Series (so called by Blake and Hudleston in 1877). But the Oxford Oolite of 

Headington and elsewhere round Oxford is only a detrital deposit made up 

of coral- and shell-fragments, and is as abnormal a facies as the Coral Rag. 

There seems, therefore, to be some justification for retaining Blake and Hudleston's 

name for the series as a whole, embodying as it does the name of a 

locality where the oolite is largely a true oolite and is far more thickly developed. 

(The typical sections at Osmington are shown in Plate XVI, p. 380.) 

Perhaps the chief objection to reviving the term Oxford Oolite in its original 

sense (more important than the essentially non-oolitic structure of the great 

bulk of the Wheatley Limestones) is the variety of meanings which the name 

suggests. Phillips in 1871 used it for the whole Corallian plus Oxford Clay, 

and Buckman and some foreign geologists have used it as equivalent to 

Corallian Beds. The term Oxfordian, moreover, has been employed in England 

and abroad in so many senses that any name including the word Oxford is 

liable to be misinterpreted. 

The uncertainty prevailing at that time as to the position of the Stonesfield 

Slate is indicated by Buckland's placing it above the Great Oolite and correlating 

it on the one hand with the sandy beds at Hinton Charterhouse, near 

Bath, which we now know to be part of the Forest Marble, and on the other 

with the Collyweston Slate, since proved to be Inferior Oolite. This last 

mistake survived until nearly fifty years later. 

Of the other terms, the Calcareous Grit was transferred to its proper position 

below the Coral Rag, where it already figured in Smith's table as 'sand'. 

1 Appended to William Phillips's Selection of Facts . . , to form an Outline of the Geology 

of England and Wales, 1818.


The prefix Lower was added by Phillips in 1829, in describing Yorkshire; 

and at the same time he recognized its companion, the Upper Calcareous 

Grit. Webster's term Kimeridge (or Kimmeridge) Clay was adopted by 

Buckland to replace Smith's Oak Tree Clay, and has been in use ever since. 1 

II. D'ORBIGNY AND THE STAGES; A SYSTEMATIZED CLASSIFICA- 

TION BASED ON A COMBINATION OF PALAEONTOLOGY 

AND STRATIGRAPHY 

William Smith had no claims to rank as a palaeontologist according to the 

modern meaning of the word, and yet he was certainly a practical stratigraphical 

palaeontologist of no mean attainments. Since the early days of his 

boyhood in the Oxfordshire village of Churchill, where he played at marbles 

with the Terebratulids from the Clypeus Grit and noticed that the large 

Clypei were used as 'poundstones' or weights by the cottagers, he was a close 

observer and collector of fossils. He was the first to recognize their value in 

the determination of strata, and we are told how he rarely returned from his 

numerous rides and walks without his pockets bulging with 'identifying 

fossils', to guide him in entering the boundary-lines upon his map. In his 

stratigraphical arrangement of the Rev. Richardson's collection, which caused, 

as we have just seen, such incredulity and later, when the principles were 

demonstrated, such unbounded admiration, he showed himself to have 

mastered thoroughly the successive assemblages of fossils contained in the 

oolitic formations. That he could turn them to such useful account although 

he had no names for most of them is an object-lesson which many modern 

workers might with advantage take to heart. 

The axiom that 'the same strata are found always in the same order of 

superposition and contain the same peculiar fossils' was quickly accepted and 

the correlation of the strata in other parts of England, partly by means of 

lithology and partly by means of their fossils, was rapidly pushed forward by 

Smith's successors. Before 1830 there had already appeared the two monographs 

which remain undisputedly the prototypes of all regional stratigraphical 

treatises—Fitton ? s great memoir on The Strata between the Chalk and 

the Kimeridge Clay in the South-East of England (1827) and John Phillips's 

Illustrations of the Geology of Yorkshire, or a Description of the Strata and 

Organic Remains of the Yorkshire Coast (1829). As new areas came to be 

studied it was soon realized that the lithological characters of the formations 

changed from place to place, but that, even if they lost their identity entirely, 

as often happened in Yorkshire, they could still be recognized by their contained 

fossils. 

This conception of the independence of fossils from facies was perfectly 

familiar to Phillips by 1829 and can scarcely have been foreign to William 

Smith ten years earlier, though we seldom find it formulated. It is only 

occasionally that a gleam of light reveals the inner working of men's minds 

about this time, for the output of a great mass of important descriptive matter 

was engaging most of their attention. 

Some of the first definite attempts to formulate ideas of detailed correlation 

solely by means of fossils emanated from an obscure geologist, Louis Hunton, 

whose collecting ('zonal' in the full modern sense of the word) among the 

1 For note on the spelling of this see footnote on p. 441.

D'ORBIGNY AND THE STAGES 9 

Middle and Upper Lias of the Yorkshire Coast, at the same time as W. C. 

Williamson's, will be referred to later on. 

If these ideas were slow to take shape in England, they soon afterwards 

made rapid progress in France, led by a man of vision, Alcide d'Orbigny. 

Realizing the all-important factor in the correlation of strata in different 

localities to be the fauna, and impatient at the indefinite multiplication of 

local names for beds of differing lithological development but of the same age, 

he sought to sweep aside lithology and give to the beds containing each successive 

assemblage a single name. The groups of strata indicated by these names 

he called stages. 'It will be seen from the nomenclature adopted in naming 

these stages', he explained, 'that I have endeavoured ... to choose names 

drawn from the localities where a stage is best developed, 1 in order to put an 

end to this jumbled nomenclature, based on the local lithology, which varies 

so greatly according to the place, and on the fossils which happen to be predominant 

at one locality, but may be wanting elsewhere.' 2 

Ten of these Stages were to be recognized in the Jurassic System, and 

no ambiguity was left as to the basis on which they were to be established. 

'Geologists in their classifications', wrote d'Orbigny, 'allow themselves to be 

influenced by the lithology of the beds, while I take for my starting-point . . . 

the annihilation of an assemblage of life-forms and its replacement by another. 

I proceed solely according to the identity in the composition of the faunas, or 

the extinction of genera or families.' 3 

These words are momentous ones. D'Orbigny's stage-names have been so 

widely adopted that it is important that there should be no misunderstanding 

of their true nature, and it seems advisable that all who use them should have 

some acquaintance with d'Orbigny's methods and aims expressed as nearly as 

possible in his own words. At the end of the first volume of the Paleontologie 

frangaise; terrains jurassiques he gives the following as part of a Resume 

geologique: 

'Division of the Jurassic Rocks in Stages' 

'Many subdivisions have already been proposed for the Jurassic rocks, some 

based on the lithological character,: of the beds, others on the dominance of some 

fossil or another. I do not intend to discuss the worth of the successions established 

by these methods; all, when they are the result of direct observation .and not of 

theorizing, set forth local or general facts of great interest; but when one comes to 

co-ordinate them, obstacles at once appear. How are groupings based only on 

lithological characters to be dealt with, when they have been seen to be misleading? 

On the other hand, how can one rely on the nomenclature of the fossils recorded in 

a succession of beds, when one sees these fossils identified by authors with such 

irresponsibility that it is often necessary to ignore half of the identifications ? . . . 

Confronted with these insurmountable difficulties I have found only one solution 

possible, and that was to consult nature herself. Since my first observations on 

the rocks of France, I have realized that in crossing the successive beds from the 

older to the younger, I have everywhere met with the same sequence of fossil 

faunas, restricted within the same vertical limits in the geological succession, 

1 His system of naming the strata with terminations in -ien was started by Brongniart, who 

published a remarkable Tableau des terrains qui composent Vecorce du globe in 1829, in which he 

adapted some of the old names (Oxfordien, Portlandien, Purbeckien) and coined some new 

(Havrien); see table on p. 11. 

2 A. d'Orbigny, 1842-9, Paleontologie franpaise; terrains jurassiques, vol. i, p. 604. 

3 A. d'Orbigny, loc. cit., p. 9.


whatever might be the lithological composition of the beds containing them. 1 I have 

also recognised that the lithology has done nothing but mislead observers, by making 

them see imaginary likenesses, such as between the ferruginous beds on the opposite 

sides of France, which contain totally distinct faunas (nevertheless confounded) 

although the same faunas are found on corresponding horizons in beds of different 

lithology and often remote from one another. I therefore set myself the task of 

following up the palaeontological horizons in the beds of which I was making a preliminary 

study, wherever they were to be found, in order to satisfy myself whether 

they signalized a definite period or only a local facies, governed by bathymetrical 

considerations. After having obtained in all parts of France—north, south, east 

and west, in Provence as in Normandy, in the Ardennes as well as in the Vendee,— 

the same results, and having found nothing but one confirmation after another over 

a period of fifteen years, without encountering a single contradictory fact, I at last 

became convinced that the Jurassic rocks were divisible into ten zones or stages, 

demarcated as well by the different faunas they contain as by stratigraphical boundaries 

2 which reappeared again and again at every point. I have followed them one 

after another around the basins in France and outside; I have ascertained that in 

no single locality do they become confused, and that they represent as many distinct 

geological epochs succeeding one another in a constant and regular order. This fact 

gained, it remained to assure myself whether these different stages established in our 

country were the result of local circumstances peculiar to France, or if they were due 

to general causes operative simultaneously all over the world. Happily I had the 

means of solving this last problem. 

'The researches carried out in Russia by Messrs. Murchison, de Verneuil, von 

Keyserling and Hommaire de Hell placed within my reach the knowledge, derived 

from a comparative study of the faunas in the Jurassic rocks of that country with 

those of France, that from the Crimea to Moscow, and thence as far as the north of 

the Urals, all the several members of the Jurassic formation observed corresponded, 

in their faunas, with our French stages. The same may be said of England and 

Germany, whither extend the same ancient basins as those in France. The Jurassic 

fossils of Central America, collected by Messrs. Darwin and Domeiko, have led me 

to the same conclusions, just as have those of the Province of Cutch in India. In 

fact these isolated localities, immensely remote from one another, have in common 

with our French stages not only a general similarity in their faunas, but frequently 

also several identical species, which prove their perfect contemporaneity. These 

distant confirmations of my own observations on the Jurassic rocks assured me at 

the same time that the causes of the separation of the stages were general. ... I was 

therefore bound to adopt them for the double reason that there is nothing arbitrary 

about them and that they are, on"the contrary, the expression of the divisions which 

nature has delineated with bold strokes across the whole earth.' 3 

These are the words of an enthusiast carried away by his subject and unfettered 

by too much knowledge. The idea that inspired them was magnificent, 

and if d'Orbigny, without being anticipated by any one with less breadth of 

outlook, had lived and launched his system half a century later, he would 

probably have rendered stratigraphy the greatest service standing to the credit 

of any man. By then he could no longer have entertained such an idea of 

universal uniformity and simplicity, and his stages would have been far more 

numerous. Like the many other aspects of nature, which have appeared to 

some to offer scope for grand generalizations, this turned out to be of almost 

infinite complexity. 

1 So far he is merely following William Smith. 

2 'lignes de demarcation stratigraphique'. 

3 Alcide d'Orbigny, 1842-9, loc. cit., pp. 600-3.

D'ORBIGNY'S STAGES ii 

TABLE II. D'Orbigny's stages and zones, and the stratigraphical terms employed 

by Brongniart. 

; 

BRONGNI ART'S ' 

TERMS, 1829. | 

D'ORBIGNY, 1842-9. 

Etages Zones de 

Calcaire PURBECKIEN , — — 

Calcaire PORTLANDIEN PORTLANDIEN 

Marne argileuse 

HAVRIENNE 

KIMMERIDGIEN 

Calcaire CORALLIQUE CORALLIEN 

Marne OXFORDIENNE j OXFORDIEN 

— j CALLOVIEN 

Oolithe Miliaire I BATHONIEN 

— BAJOCIEN 

— TOARCIEN 

— LIASIEN 

— 

SINEMURIEN 

Ammonites giganteus 

Ammonites irius 

Trigonia gibbosa 

Ammonites lallieri 

Ostrea deltoidea 

Ostrea virgula 

Ammonites altenensis 

Iceras arietina 

Ammonites cordatus 

Plicatula tubifera 

Trigonia clavellata 

Ammonites Jason 

Ammonites refractus 

Ostrea dilatata 

Ammonites bullatus 

Terebratula digona 

Ostrea acuminata 

Ammonites interruptus Brug. (parkinsoni 

Sow.) 

Trigonia costata 

Ammonites bifrons 

Lima gigantea 

Ammonites margaritatus 

Ostrea cymbium 

Ammonites bisulcatus 

Ostrea arcuata 

Few of the geologists working in other countries at first adopted d'Orbigny's 

stages, for with their more detailed local knowledge they were unable to 

recognize any such ten divisions which might have been 'delineated by nature 

with bold strokes across the whole earth'. Quenstedt, who published his 

principal work Der Jura a decade later, but had already completed a detailed 

study of the Jurassic rocks of Wurttemberg, and was undoubtedly the greatest 

authority on the subject at that time, was withering in his criticism of the 

superficiality and inaccuracy of d'Orbigny's work. His ire was in large 

measure aroused by the fact that d'Orbigny had ignored the priority of his 

work and that of his compatriots. Nevertheless his eight pages of criticisms 

are extremely telling. 1 

Other workers (for the most part French and Swiss) took up d'Orbigny's 

idea but made more stages to suit their own districts. By I860 there had 

already been added VESULIEN, ARGOVIEN and SEQUANIEN (Marcou, 1848), 

PT£ROCERIEN, ASTARTIEN and VIRGULIEN (Thurmann, 1852), DICERATIEN 

1 F. A. Quenstedt, 1858, Der Jura (Tubingen), pp. 17-24.


and SPONGITIEN (fitallon, 1857), PLIENSBACHIEN (Oppel, 1858), BRADFORDIEN 

and DUBISIEN (Desor, 1859), and MANDUBIEN (Marcou, i860). The greatest 

manufacturer of stages was Mayer-Eymar, who brought out four works in 

1864,1881,1884 and 1888, in which he introduced no less than 30 new names, 

all taken from places but differing slightly from the standard set by Brongniart 

in having terminations in -on or -in. 1 The game has not ceased since Mayer- 

Eymar, and there are now at least 100 stage-names to be fitted into the 

Jurassic System, defined with varying degrees of accuracy according to the 

capacity or the outlook of the author (see Appendix). 

Thus by their ardour the disciples of d'Orbigny have entirely defeated his 

ends. They have 'improved' his system until nothing is left of it but a meaningless 

complex of overlapping stages of differing values, not in the smallest 

degree more efficient than the old nomenclature which it was designed to 

replace. 

Yet by this painful process a truer picture of nature has been achieved. There 

was a cataclysmic bias which gave an inherent improbability to d'Orbigny's 

theory of ten successive faunas, occupying the whole earth for a span 

and then being swept away everywhere simultaneously. The wider and the 

more detailed that our knowledge grows, the more apparent does it become 

that the changes took place in a continuous stream. Earth movements, like 

evolution, never ceased, only varying in degree of slowness at different times, 

in different parts of the globe. By their agency the environment of the forms 

of life inhabiting the sea was constantly changing, and thus giving rise to 

incessant migration and to the extinction of some species and the evolution 

of new. A sentence written by Sir Andrew Ramsay in 1864 in reference to the 

Lias might well apply in some region or other to the whole sedimentary 

series: 

T incline to the idea that, considering the frequent large percentages of passage 

[of species from one part of the Lias to the next] (ranging as high as 50 per cent.), 

we are justified in supposing that migration of what were old species here into new 

areas elsewhere, and of certain older species from other areas into ours, may account 

for the very incomplete breaks in the succession of Liassic life in England, more 

especially if there were occasional pauses in the deposition of the strata.' 2 

In other respects too, there is much to criticize in d'Orbigny's scheme of 

Stages. In the first place, while decrying 'this jumbled nomenclature, based 

on local lithology . . . and on the fossils which happen to be predominant at 

one locality but may be wanting elsewhere', he not only adopts Thurmann's 

term Corallien, derived from William Smith's Coral Rag, but also coins an 

altogether new and horrible hybrid, 'Liasien'. 3 That he should have left these 

1 These terminations were designed to show that they were only to rank as substages, and 

the principle was accepted at the Third International Geological Congress at Berlin in 1883 

(Compte Rendu, published in 1888, pp. 323 et seq.). The substage in -in was defined as equivalent 

in value to the French term 'assise', which has no exact equivalent in English. The 

higher of two substages was to end in -in, the lower in -on, in every stage subdivided. 

2 A. Ramsay, 1864, Address to the Geological Society, Q.J.G.S., vol. xx, p. li. 

3 William Smith's term 'Lias', in use to this day among the quarrymen of the West of 

England, is often supposed to be a corruption of the word 'layers'; Buckman, however, considered 

it to be an ancient Gaelic word leac, meaning a flat stone, which is embodied in such 

place-names as Llechryd, Lechlade, Leckhampton, and survives in Brittany as liach, leach, 

a stone. In old French it occurs as liais, meaning a hard freestone from which steps and 

tombstones were made. (Type Ammonites, vol. i, 1910, p. xv.) Buckman is probably right, 

for in the West of England dialects 'layers' would never become 'lias' as it would in the 

mouths of cockneys.

CRITICISMS OF THE STAGE-NAMES 13 

inconsistencies in his otherwise uniform table of adjectival place-names is 

strange. Many of his followers have been equally inconsistent, and from any 

finally revised scheme of classification by stages that may be adopted in the 

future will have to be expunged the terms ASTARTIEN, PTEROCERIEN, STROM- 

BIEN, VIRGULIEN, CORALLIEN, CORALLINIEN, ZOANTHARIEN, SPONGITIEN, 

CYMBIEN, DICERATIEN, GLYPTICIEN, OPALINIEN, and PHOLADOMYEN. Besides 

these there are a few terms that stand in a class apart, for they are not founded 

on place-names and so are not strictly conformable to the scheme, although 

they may be useful. Among these are Woodward's FULLONIAN (1894), which 

is anyhow antedated by CADOMIN (Mayer-Eymar, 1881, after Caen); and 

Oppel's TITHONIAN, 1 which is akin to such terms as Eocene and Miocene. 

Liasien, which is equivalent to the Middle and part of the Lower Lias, has 

been superseded by DOMERIAN 2 (Bonarelli, 1894) and CHARMOUTHIAN (Mayer- 

Eymar, 1864). Oppel first suggested PLIENSBACHIEN as a substitute, but as it 

included part of the Lower Lias it has fallen into disuse as being too crude. 3 

Charmouthian is open to the same objection, and in 1913 Dr. Lang suggested 

replacing the name for the lower part of the Charmouthian, below the 

Domerian, by the form CARIXIAN (from Carixa = Charmouth). 4 

A far more serious criticism of d'Orbigny's method is that he adopted names 

of places in foreign countries, particularly in England, which had already been 

associated for many years with a particular series of strata, without ascertaining 

exactly what those names meant in the place of their origin. Just as any 

name of a place conferred on a fossil, if confusion is to be avoided, should be 

that of the locality from which the type-specimen was derived, so when a 

stage is introduced into stratigraphy it should be defined according to the 

development of the strata in the locality from which it takes its name. By 

adding -ien to names with such old-established geological associations as 

Kimeridge, Portland, Oxford, and Bath, d'Orbigny sought to change their 

meanings entirely, adapting them to suit the succession where he knew it best, 

in the North of France. The result is that many of his names refer to now 

well-known but then only vaguely-known successions in England, while his 

palaeontological definitions refer to the succession in France. There is strong 

justification for the movement to redefine his stages so that they shall correspond 

with the strata developed at the localities after which they are named, 

and so with the strata bearing the same names previously. 5 

All this points to the fact that d'Orbigny's scheme of classification was premature. 

The ideal would have been to wait until a tolerably complete record 

of the succession of Jurassic faunas had been elucidated, by piecing together 

the results obtained by workers in different parts of Europe, and then, bearing 

in mind the original scope of the old terms, to divide up the column so that 

each division should carry the name of the locality or region where its particular 

1 Tithon was the spouse of Eos, Goddess of the Dawn. 

2 From Monte Domero, in the Lombardy Alps. 

3 A. Oppel, 1856-8, Die Juraformation, p. 815. Pliensbach is a village in Swabia. 

4 See, however, the terms VIRTONIAN (from Virton, Belgium) and LOTHARINGIAN from 

Lothringen = Lorraine), both already applied to all or part of the Pliensbachian. (See Appendix 

at end of this book.) 

s Various opinions on the necessity for consistency in the names used in stratigraphy were 

offered at the Second and Third International Geological Congresses at Bologna in 1880 and 

Berlin in 1883, but no satisfactory conclusions were arrived at and, as no rules were formulated, 

the results of the debates have been little heeded.


fauna or group of faunas was best developed. For this the time w r as not yet 

ripe, and much of the confusion in international nomenclature and correlation 

has been caused by d'Orbigny's attempt to take a short cut, omitting an indispensable 

stage in the evolution of the science. 

III. QUENSTEDT AND OPPEL TO BUCKMAN; ZONES AND THE 

SEARCH FOR AN INDEPENDENT TIME-SCALE 

The laborious course which stratigraphy had still to take, and of which it 

has not yet reached the end (the following chapters are a humble contribution 

to its advance) was tersely enunciated by Quenstedt in his criticism of 

d'Orbigny's method. 

'The next task which we have to fulfil in connection with the Jurassic is to draw up 

sections as faithfully as possible in the different districts. . . . The accurate comparison 

of two successive beds three inches thick by means of their actual contents 

can contribute more fruitfully to the development of the science than the cataloguing 

of stages from the farthest corners of the earth, when it has immediately to be 

admitted, as a matter of course, that they are not correct. ... Of what avail is it if 

a man has seen the whole world, and he does not understand aright the things which 

lie in front of his own doors?' 

And again: 

'Let us not weary of searching our strata; let each one of us collect as much as 

he can in his own neighbourhood, labelling the specimens exactly with their 

localities, and compare them with the material collected by others; then at least the 

first goal of all geological research should not remain far from our reach—a true 

table of the succession of the strata.' 1 

This detailed and truly scientific palaeontological method, of which Quenstedt 

was at once the leading champion and the foremost exponent, had been 

pursued quietly in various parts of Europe for at least twenty years. In 

England it was earliest cultivated by a band of palaeontologists, far ahead of 

the thought of their time, in the intellectual centres of Whitby, Scarborough 

and York. A short paper published in 1836, by one of the first of them, Louis 

Hunton, is a truly remarkable document. This pioneer had already perceived 

that 'Of all organic remains, the Ammonites afford the most beautiful illustrations 

of the subdivision of the strata, for they appear to have been the least 

able ... to conform to a change of external circumstances.' He applied his 

discovery to a minute study of the Middle and Upper Lias in the Whitby 

cliffs and alum works, with results which show the surprising progress already 

being made, at this early date, in the observation and selection of shortranged 

fossils of zonal value. Next to his paper was printed a more ambitious 

project of the same type by W. C.Williamson, but this was more a catalogue 

of fossils arranged according to their horizons. 2 

After describing the Jet Rock, and remarking that 'on inspection of the 

section, it will be perceived, that the Jet Rock has its peculiar suite of Ammonites', 

Hunton passes on to an accurate analysis of the fauna of the Marlstone 

of the Middle Lias: 

'The species of Ammonites, though few in number, are, however, highly characteristic; 

thus we find A. vittatus about the centre of the series, confined to a very 

1 F. A. Quenstedt, 1858, Der Jura, pp. 23, 823. 

2 W. C. Williamson, 1836, Trans. Geol. Soc. [2], vol. v, pp. 223-42, and vol. vi, 1841, 

pp.143-52.

HUNTON, WILLIAMSON, AND MARTIN SIMPSON 15 

small range, associated in nodules with the Cardium multicostatum, Turbo undulatus, 

and Pecten planus; but the two latter occur in other parts of the formation. The 

A. maculatus is constantly found at the junction of the marlstone with the lower 

lias, which here pass so gradually into each other, that it is impossible to determine 

where the sandstones end and the blue shale begins. I have long sought for A. 

maculatus in the upper and central portions of the marlstone, but have never found 

it many feet above the junction beds; and though this and other Ammonites from 

unequal geographical distribution, may be more abundant in one place than in 

another (A. maculatus is in greater number at Staithes, A. Hawskerensis at Hawskerbottoms), 

yet they constantly maintain an invariable relative position. . . . 

'The above description', he concludes, 'may not, in some instances, exactly accord 

with previous statements, but one great source of error has hitherto been the collecting 

of specimens from the debris of the whole formation, accumulated at the foot 

of cliffs or other similar situations, where they have long laid, and the inferring of 

their position from the nature of the matrix.' 1 

The publication of Hunton's paper preceded by one year the appointment 

of Martin Simpson to be Curator of the Museum of the Whitby Literary and 

Philosophical Society in succession to John Bird. The new curator on taking 

up his position found in the museum large collections of ammonites from the 

Yorkshire Lias (among them perhaps Hunton's specimens), and he set himself 

to describe them. In 1843 he published descriptions of more than 100 

species, 2 followed in 1868 by a detailed section of the Whitby cliffs. Simpson 

was a close follower of Hunton's methods. 'Being convinced by observation', 

he wrote, 'that few species of the Lias fossils had existed during the deposition 

of any great thickness of strata, but, on the contrary, were often confined to 

thin seams, I measured carefully, with a two foot rule, all the beds and seams 

of Lias both to the south and north of Whitby, and at the same time collected 

the fossils from each stratum.' 3 

These examples serve to illustrate the kind of work that was proceeding in 

various parts of Europe, by means of which alone, as Quenstedt perceived, 

real progress was to be made. The names of many other Englishmen could 

be added to those of Simpson and Hunton; those of Leckenby, Bean and 

Williamson especially should not be omitted. 

The man, however, who was to place the whole science of stratigraphical 

geology on a new footing and to breathe new life into it was Albert Oppel. It 

was appropriate that one who accomplished so much in this sphere should 

have been a pupil of Quenstedt's at Tubingen. A young man, gifted with more 

than ordinary powers of observation, generalization and exposition, he acquired 

world-wide fame at the age of twenty-five by his studies in the Jurassic 

rocks. It was therefore the more tragic that in 1865 he fell a victim to typhoid 

fever and died, at the early age of thirty-four. 

After acquainting himself thoroughly with the strata at home, in Swabia 

and Wurttemberg, so lucidly and minutely described by his master, Oppel set 

out in 1854 on a tour of the Jurassic regions of Switzerland, France and 

England, with the object of correlating them in greater detail by means of 

1 Louis Hunton, 1836, Trans. Geol. Soc. [2], vol. v, pp. 216-18. For calling my attention to 

the remarkable qualities of this forgotten paper I am indebted to Prof. Davies's 'Geological 

Life-Work of S. S. Buckman' and H. B. W'oodward's History Geol. Soc.y p. 121. 

2 Many of these have been figured in Buckman's Yorkshire Type Am?nonitesy which was 

originally undertaken expressly for that purpose. 

3 Published in 1868 in a Guide to the Geology of the Yorkshire Coast, ed. 4; reprinted in 

Fossils of the Yorkshire Lias, ed. 2, 1884, pp. ix-xxiii.


fossils especially chosen for their wide horizontal and small vertical range. He 

stated the problem before him as follows: 

'Comparison has often been made between whole groups of beds, but it has not 

been shown that each horizon, identifiable in any place by a number of peculiar 

and constant species, is to be recognized with the same degree of certainty in distant 

regions. This task is admittedly a hard one, but it is only by carrying it out that an 

accurate correlation of a whole system can be assured. It necessarily involves exploring 

the vertical range of each separate species in the most diverse localities, while 

ignoring the lithological development of the beds; by this means will be brought 

into prominence those zones which, through the constant and exclusive occurrence 

of certain species, mark themselves off from their neighbours as distinct horizons. 

In this way is obtained an ideal profile, of which the component parts of the same 

age in the various districts are characterized always by the same species.' 1 

This passage represents one of the most important landmarks in the progress 

of stratigraphical geology, for it contains the first germ of the conception 

of a detailed time-scale, abstracted from all local considerations, either 

lithological or palaeontological. Before it geological history had been as 

confused as the history of Assyria and Babylonia at the time of the city-kingdoms, 

each with its individual local chronology, overlapping those of its 

neighbours. Since Oppel, historians have been provided with an orderly 

system of dynasties, subdivided into reigns, and even in countries as distant 

as the Himalayas it has been possible to discern marks appropriate to the 

periods when the more important of the dynasties held sway, although the 

influence of the individual reigns was not always felt outside North-Western 

and Central Europe. 

It is remarkable that Oppel nowhere defined what he meant by a zone. He 

is frequently credited with the first use of the word, but it had in fact been 

employed by several French geologists before him, and a definite meaning was 

already attached to it. Oppel adopted the term and accepted its meaning and 

no doubt it seemed to him in consequence unnecessary to give a definition. 

The first occurrences seem to be in the writings of d'Orbigny (1842-52) and 

Hebert (1857). D'Orbigny employed it in exactly the same way as the term 

Stage, except that he reserved it for palaeontological use; thus he speaks of 

the Bajocian Stage as constituting the zone of a named group of fossils. 2 

An example will make the matter clearer: 

7 e fitage: SINEMURIEN, d'Orb. 

Premiere apparition, de l'ordre des Insectes dipteres . . . (&c.). 

Regne des genres Car dim a, Spiriferina, Octoccenia. 

Premiere periode. De la faune speciale aux terrains jurassiques. 

Zone du Belemnites acutus, des Ammonites bisulcatus et catenatus, du Cardinia 

hybriday de VUnicardium cardioides, de VOstrea arcuata, et du Spiriferina walcotii. 

Hebert, on the other hand, chose index-fossils and referred to the zone of a 

certain named species; e.g. 'la zone (or assise) a Am. primordialis'. 3 

From these earlier uses of the term zone Oppel did not deviate. If he had 

1 A. Oppel, 1856-8, Die Juraformation Englandsy Frankreichs und des Sudwestlichen 

Deutschlands, Stuttgart, p. 3. 

2 A. d'Orbigny, 1849-52, Cours elementaire de Paleontologie et de Geologie stratigraphique, 

Paris, pp. 433 et seq. (The Palaeozoic 'stages' were treated in the same way on earlier pages. 

The same use was made of the word 'zone' in the Paleontologie frangaise, but not in tabular 

form; I append a tabulation in Table 11, p. 11.) 

3 E. Hebert, 1857, Les mers anciennes et leurs rivages dans le bassin de Paris, i e Partie, 

Terrains jurass. Paris, pp. 18, 23 (assise, p. 22).

OPPEL AND THE ZONES 17 

given a definition of what he understood by the term it would have been in 

fact superfluous, for his meaning is apparent on almost every page of his book. 

He even says that although he has elected to name his zones after fossils, they 

could equally well have been named after places. 

To Oppel, therefore, is due, not the credit for the inception of the zonal 

idea, but for a very great refinement in its use, and, most important of all, for 

emancipating the zones from the thralls both of local facies, lithological and 

palaeontological, and of cataclysmic annihilations, thus giving them an enormous 

extension and transferring them from mere local records of succession 

to correlation-planes of much wider (theoretically universal) application. 

Oppel's first zonal table for the Jurassic, here reproduced (Table III, p. 18), 

is a document of considerable interest. He evidently appreciated, as had 

Louis Hunton in England twenty years earlier, that 'of all organic remains the 

Ammonites afford the most beautiful illustrations of the subdivision of the 

strata', for of his 33 Jurassic zones 22 were assigned ammonites as indexfossils. 

Of the remainder, 5 were named after lamellibranchs, 2 after brachiopods, 

2 after echinoderms and 1 after a gastropod, while 1 was left to be 

named later. All the zones to which Oppel originally assigned indices other 

than ammonites have since had ammonites found for them. 

Since the time of Oppel nearly every geologist who has pursued local studies 

of the Jurassic System has found it necessary to increase the numbers of the 

zones in order to bring his stratigraphical scheme into closer relationship with 

nature. Oppel himself wrote: 'The difficulty [of constructing an adequate 

zonal table] arises chiefly from the insufficient number of well described 

species. The more accurately the species are defined, the more exactly can 

the beds be subdivided.' 1 Thirty-five years later Buckman was still echoing 

the same complaint: 'Anyone unacquainted with the Dorset-Somerset Inferior 

Oolite, and the richness of its deposits, could scarcely credit the 

difficulty experienced in these investigations from want of names for the 

ammonites. Species which have been perfectly well known for years as indicators 

of certain horizons are altogether devoid of any specific name. They 

could not, therefore, be recorded with any precision.' 2 Buckman in order to 

make good this defect devoted much of his time in the later part of his life to 

figuring and naming more and more ammonites in his work, Yorkshire Type 

Ammonites, and its continuation, Type Ammonites. At the time of his death 

he had figured in this series no less than 797 species, illustrated in 1,052 plates. 

It need not concern us here to trace the stages by which Oppel's first essay 

in a zonal table has become elaborated by a host of stratigraphers until the 

present formidable tables of zones have been evolved. Suffice it to say that, as 

with the designation of beds and stages, complete independence of action is 

allowed the individual author, and he is at liberty to cumber the terminology 

with as many new zones as may seem to him desirable, no matter how local 

his requirements, his knowledge, or his outlook. 

IV. BUCKMAN AND THE MODERN CHRONOLOGY 

From the examples quoted of the earliest uses of the word zone, as adopted, 

elaborated and refined by Oppel, it will be evident that it is purely a stratigraphical 

term—a bed or group of bedsy identified by palaeontological criteria 

1 A. Oppel, 1858, Die Juraformation, p. 3. 2 S. S. Buckman, 1893, Q.J.G.S. vol. xlix, p. 482.

Formationsabtheilungen. 

Oberer Jura oder 

Malm. 

Mittlerer Jura oder 

Dogger. 

Unterer Jura oder 

Lias. Lias. Lias. Lias. Lias. Lias. Lias. Lias. Lias. Lias. Lias. Lias. Lias. Lias. Lias. 

Etagen oder 

Zonengruppen. 

i8 

TABLE III. Oppel's Table of Zones. 

Zonen (Lager oder Stufen, d. h. 

palaontol. bestimmbare 

Schichtencomplexe). 

Zone der Trigonia gibbosa. 

Kimmeridge- Zone der Pterocera Oceani. 

gruppe. 

Zone d. Astarte supracorallina. 

?{ Zone der Diceras arietina. 

Gonybeare 

& Phillips. 

1822. 

England. 

Upper 

Division 

of Oolites. 

}? 

Oxford- 

Zone des Cidaris florigemma. 

gruppe. Low. calc. grit & Scyphienkalke. 

Middle 

Zone des Amm. biarmatus. Division 

Zone des Amm. athleta. 

of Oolites. 

Kellowaygruppe. 

Zone des Amm. anceps. 

Zone des Amm. macrocephalus. 

Bathgruppe. 

Bayeuxgruppe. 

Zone der Terebr. lagenalis. 

Zone der Terebr. digona. 

Zone des Amm. Parkinsoni. 

Zone d. Amm. Humphriesianus. 

Zone des Amm. Sauzei. 

Zone des Amm. Murchisonae. 

Zone der Trigonia navis. 

Zone des Amm. torulosus. 

Thouars- Zone des Amm. jurensis. 

gruppe. Zone der Posidonia Bronni. 

Pliensbachgruppe. 

(Liasien d'Orb.) 

Semurgruppe. 

Zone des Amm. spinatus. 

Obere Z. d. A. margaritatus. 

Untere Z. d. A. margaritatus. 

Zone des Amm. Davoi. 

Zone des Amm. ibex. 

Zone des Amm. Jamesoni. 

Zone des Amm. raricostatus. 

Zone des Amm. oxynotus. 

Zone des Amm. obtusus. 

Zone des Pentacr. tuberculatus. 

Zone des Amm. Bucklandi. 

Zone des Amm. angulatus. 

Zone des Amm. planorbis. 

Lower 

Division 

of Oolites. 

Lias. 

Dufr6noy & 

£lie de 

Beaumont. 

1848. 

Frankreich. 

£t. sup£r. 

du syst&me 

oolithique. 

titage 

moyen du 

syst&me 

oolithique. 

titage 

inf£rieur 

du syst&me 

oolithique. 

Calcaire h 

Gryph6es 

arqu£es ou 

Lias.

DEFINITION OF ZONE 19 

(by a fossil or an assemblage of fossils). The chosen fauna is the constant 

term; the lithic characters and their concomitant facies-faunas may be subject 

to indefinite variation. It is important that this conception should be perfectly 

clear. It is perhaps best stated in the form of a definition; and one of the most 

concise is due to Prof. Marr: 'Zones are belts of strata, each of which is 

characterized by an assemblage of organic remains, of which one abundant 

and characteristic form is chosen as index.' 1 An official definition was 

enunciated at the third session of the International Geological Congress in 

1883: 'A zone is a group of beds, of an inferior status, characterized by one or 

several special fossils which serve as indices.' 2 From time to time erroneous 

interpretations are put forward, due to confused thinking. For instance, 

H. B. Woodward, in a special article on zones, defined them as 'assemblages of 

organic remains'. 3 As Buckman remarked, the fossils in a museum might be 

called a zone according to this definition. 

It will be noticed that in all these definitions and uses of the word zone there 

is no mention of time. It is, of course, implicit in Oppel's and all other 

authors' tables of zones, stages or strata, that they occupied a certain time in 

forming, and that the subdivisions probably occupied a lesser time than the 

major divisions. Before 1893, however, we find no attempt to formulate any 

strictly chronological ideas, or to construct a time-scale independent of strata, 

whereby might be compared the relative time taken to deposit strata in 

different localities. No vocabulary for any such conceptions existed. 

The year 1893 saw the passing of another landmark along the path of stratigraphical 

geology. This time the advance was due to the work of an Englishman, 

and again it resulted from studies in the Jurassic System. Sydney S. 

Buckman was born in i860 at Cirencester, Gloucestershire, where his father 

was Professor of Geology at the Agricultural College, and, when three years 

old, he was moved to Bradford Abbas, near Sherborne, Dorset, whither his 

father retired to take up farming. 4 He was thus brought up amid one of the 

most richly fossiliferous districts in the whole world, where the ammonites 

are packed in incredible numbers in the thin beds of the Inferior Oolite formation. 

His surroundings had a powerful effect on him. At the age of eighteen 

he was already the author of a paper on the Astartes of the Inferior Oolite, 

which he followed up at the age of twenty-one with another paper on the 

ammonites. These studies were only the prelude to activities of body and of 

mind which were to revolutionize much of the accepted geological thought of 

his time. After making himself master of his own district, the rich and intricate 

Sherborne country, he set forth to apply his restless mind to ever-expanding 

problems, until nothing less than the whole British Jurassic System, to the 

far north of Scotland, was his undisputed province. 

The work with which we are here concerned was the first of Buckman's 

stratigraphical papers, published at the age of thirty-three, and setting 

forth the mature results of his researches in the Sherborne district. 5 The 

1 J. E. Marr, 1898, Principles of Stratigraphical Geology, p. 68. 

2 Compte Rendu, 3e Session, Congrds geol. int.t Berlin, 1883, p. 323. 

3 H. B. Woodward, 1892, P.G.A., vol. xii, p. 298. 

4 A. Morley Davies, 1930, 'The Geological Life-Work of S. S. Buckman', P.G.A., vol. xli, 

pp. 221-40. 

5 S. S. Buckman, 1893, 'The Bajocian of the Sherborne District', Q.J.G.S., vol. xlix, pp. 

479-522. 

8.")4371 C


stratigraphical portion of this paper will be noticed in the appropriate place 

(Chapter VIII); the part of greatest importance is that dealing with certain 

theoretical matters. Impatient with the inadequacy of the existing terminology 

to deal with any but spatial conceptions, he introduced a new term hemera 

(7) fie pa). 

'Its meaning is "day", or "time"; and I wish to use it as the chronological indicator 

of the faunal sequence. Successive "hemene" should mark the smallest 

consecutive divisions which the sequence of different species enables us to separate 

in the maximum developments of strata. In attenuated strata the deposits belonging 

to successive hemerae may not be absolutely distinguishable, yet the presence of 

successive hemerae may be recognized by their index-species, or some known contemporary 

; and reference to the maximum developments of strata will explain that 

the hemerae were not contemporaneous but consecutive. 

'The term "hemera" is intended to mark the acme of development of one or more 

species. It is designed as a chronological division and will not replace the term 

"zone" or be a subdivision of it, for that term is strictly a stratigraphical one/ 1 

And again he insists: 

'It must be particularly understood that it is used in a chronological sense as a 

subdivision of an "age".' 2 

It would be difficult to imagine anything stated much more clearly than this. 

Nevertheless, from the moment of its birth, Buckman's new term began to be 

misunderstood and misrepresented. In the discussion which followed the 

reading of the paper at the Geological Society all three speakers misunderstood 

its import and criticized it on irrelevant grounds (perhaps because Buckman 

did not himself read the communication and make the important passages 

clear). The conception of a time-scale entirely independent of deposit, so 

that it could be said that each hemera must have passed everywhere, whether 

any deposit was formed or not, seems to have been too much for many of the 

geologists of the time. The advantages of the system went unnoticed in the 

general disapproval. 

Nine years later, finding that there were still some who considered that a 

hemera was simply a subdivision of a zone, Buckman published a fresh 

explanation, 3 and this is an interesting document, both because it introduces 

some new theoretical considerations, and because it throws new light on the 

changes and development of Buckman's own ideas. He now gives two definitions 

of a hemera. One is simply a restatement in different words and an 

amplification of the first—'the subdivision of an "age", it indicates the period 

of time from the rise of one dominant species to the rise of the next'; the other 

is entirely different— 4 The hemera is the time during which a certain piece of 

work, namely, the deposition of what is called 4 'the zone", was done.' 

This second definition is irreconcilable with the first and must be rejected, 

because it is based on a misconception of the meaning of 'zone'. The same 

word cannot be used with two different meanings, and we must keep to the 

original definitions, namely that the hemera is based on 'the acme of development 

of one or more species' (1893), that it is 'the time during which a 

particular species—generally an ammonite—had dominant existence' (1898), 4 

1 S. S. Buckman, 1893, loc. cit., pp. 481-2. 

2 Ibid., p. 518. 

3 S. S. Buckman, 1902, 'The Term "Hemera",' Geol. Mag. [4], vol. ix, pp. 554-7. 

4 S. S. Buckman, 1898, Q.J.G.S., vol. liv, p. 443.

BUCKMAN'S CHRONOLOGY: HEMERiE 21 

or that it is the time during which one or more species gradually reached their 

acme, passed it, and declined (1902). 

The time taken to deposit a zone is another conception altogether. We have 

just seen that a zone is not a strictly biological unit, but a bed or group of beds 

characterized by an assemblage of organisms, one of which is chosen as indexspecies, 

but need not necessarily be either confined to its zone or found 

throughout every part of the zone. It will be obvious that such a period of 

indefinite length as may be required for the formation of a zone may embrace 

several hemerae. Buckman indicated this w r hen he first introduced the word 

hemera, for he placed several beside every zone. Jukes-Browne was misled 

by this, as many others have probably been, into supposing that a hemera was 

merely a subdivision of a zone, and so a synonym of a subzone. Against this 

confusion of spatial and chronological conceptions Buckman rightly protested, 

but there is a germ of truth in Jukes-Browne's criticism. He would have been 

very near the truth if he had said that a hemera, according to Buckman's first 

and only acceptable definition, is a subdivision of the time taken to deposit 

a zone. This broader time-unit he believed to be without a name, and he 

coined for it the term secule (from seculum). 1 Prof. Diener, however, rejects 

the term in favour of an earlier, having prior claim: the word moment was 

proposed with precisely this meaning, to be the time-equivalent of a zone, by 

the Swiss Committee for the Unification of Nomenclature, at the International 

Geological Congress at Bologna in 1881. 2 Strictly speaking, therefore, 

'moment' should take priority over secule, and Diener adopts it, with the 

variations time-moment and zone-moment. 3 On the other hand, it may with 

justice be objected that the word 'moment' was already long ago preoccupied 

in ordinary parlance for an indefinite but certainly small fraction of time, and 

to misapply it to a period of many thousands of years duration is absurd. 

Thus we have, as the unit of time corresponding to the zone, the secule, the 

time-moment or the zone-moment. What, then, is the stratigraphical unit 

corresponding to the hemera ? 

Several hemerae may be contained in one secule or zone-moment. On the 

other hand, a hemera cannot exactly be said to be a subdivision of a secule, for 

the two expressions involve different conceptions: the secule is based on the 

duration or acme of the assemblage, the hemera on the acme of a chosen 

species. The two are units on different scales, just as are centimetres and 

feet, and each must have a separate spatial equivalent. To fill this want 

Prof. Trueman in 1923 introduced the term epibole, 'as a stratigraphical 

term to cover deposits accumulated during a hemera'. 4 The word is a useful 

one, but it has not received the recognition that it deserves, for reasons which 

we shall analyse shortly. 

At this point we must examine two other terms introduced by Buckman in 

1902, 5 the biozone and the faunizone. 

The biozone was introduced as a time-term 'to signify the range of organisms 

in time as indicated by their entombment in the strata. Thus we might 

1 A. J. Jukes-Browne, 1903, 'The Term "Hemera",' Geol. Mag. [4], vol. x, pp. 36-8. 

2 Compte Rendu, 2nd session, Bologna, 1881 (1883), p. 542. 

3 C. Diener, 1918, Neues Jahrb. fur Min., &c., Beilage Bd. xlii, p. 91; and 1925 Grundziige 

der Biostratigraphie, Vienna and Leipzig, pp. 217-18. 

4 A. E. Trueman, 1923, P.G.A., vol. xxxiv, p. 20c. 

5 S. S. Buckman, 1902, loc. cit., pp. 556-7.


have the biozone of a species, of a genus, of a family, or of a larger group. The 

biozone of Ammonites would be equal to Mesozoic time; . . . the biozone of 

an Ammonite genus, Coroniceras, would be through two or three hemerae; 

the biozone of an Ammonite species would be about equal to a hemera.' The 

distinction between the biozone of a given species and its hemera may be 

expressed as the difference between its absolute duration (as indicated by its 

total range) and its acme; but since in practice neither can be very accurately 

defined, owing to the imperfections of our collecting ('collection-failure'), the 

two units become virtually synonymous. 

With hemerae and secules by which to measure time, there would seem to be 

little necessity for a third unit which is elastic and must be qualified whenever 

used. It is as easy to talk of the 'duration of Coroniceras' as of the 'biozone of 

Coroniceras'. In Germany, however, the term has been adopted in a spatial 

or stratigraphical sense, to denote the deposit equivalent to the time-interval 

for which it was originally coined. The Germans have not adopted the hemera 

and consequently they have felt no want for the corresponding stratigraphical 

term, the epibole. Instead of thinking in terms of acme they think in terms 

of total range, using the biozone. There is a difference of theory and of words, 

but in practice the result is much the same. 

In this somewhat changed sense the term biozone is useful, for we have no 

other word to denote the deposit formed during the total existence of a species, 

as indicated by its absolute range. In Buckman's original sense, however, it is 

objectionable, for it contains the root 'zone', which is a spatial term, and 

employs it in a chronological sense. Such misapplication may lead to still 

further distortions of the meaning of 'zone'; its insidious influence may perhaps 

be detected in such definitions as that of Wedekind, who thinks a zone is 

'a time-interval based on the absolute duration of a species'. 1 This is indeed 

precisely what Buckman meant by a biozone. 

Happily the biozone in this sense was anticipated by one year by a much 

better term, the American biochron, introduced by H. S. Williams in 1901. 2 

'It is essential', Williams wrote, 'to distinguish the geochron (expressed in terms 

of feet thickness of stratified sediments of uniform lithologic constitution) from the 

biochron (expressed in terms of presence in the sediments of fossils of the same 

species, genus, or family). Thus the time-value of the Hamilton formation would 

be spoken of as the Hamilton geochron; while the time-value of the species Tropidoleptus 

carinatus would be the Tropidoleptus \carinatus\ biochron.' 

Again, 

'Palaeontologists are familiar with the very long range of the species A try pa reticularis', 

Rhynchonella cuboides, on the other hand, has a very short range. In the 

nomenclature proposed (so long as both are considered to be species), the fact would 

be expressed by saying that the Atrypa reticularis biochron is longer than the 

Rhynchonella cuboides biochron/ 

It is clear that Williams intended biochrons to apply to the absolute duration 

of a species, genus, family, or any larger taxonomic group; or, as he put it, 

that they were to be 'units whose measure is the endurance of organic 

1 R. Wedekind, 1918, Centralblatt fur Min., ©V., p. 270: and see also his book, Uber die 

Grundlagen und Methoden der Biostratigraphie, 1916. 

2 H. S. Williams, 1901, Journ. Geol.y Chicago, vol. ix, pp. 579-80.

BIOZONES AND FAUNIZONES 23 

characters'. 1 In summarizing at the end of his paper, however, he tabulated the 

word under a looser definition as 'the time-equivalent of a fauna or flora', 2 

which would make it the equivalent of a secule or zone-moment. Diener 

accepted this latter meaning and so dropped the word in favour of 'moment', 

saying 'The duration of a species I call, in agreement with Buckman, a biozone'. 

3 I think it will be agreed, however, that Williams's earlier definitions in 

the text of his paper must stand, and from them there can be no possible doubt 

that in introducing the biochron he had the same idea in mind as Buckman 

expressed a year later in the biozone. 4 

Buckman's second term, faunizone, was defined as follows: 'faunizones 

are, to paraphrase Mr. Marr, "belts of strata, each of which is characterized by 

an assemblage of organic remains", with this provision, that faunizones may 

vary horizontally or vertically, or the strata may not vary and yet may showseveral 

successive faunas. So faunizones are the successive faunal facies 

exhibited in strata.' 5 The term therefore expresses almost exactly what was 

originally meant by a zone. It has been adopted in Germany in the form 

Faunenzone, while the simple term zone by itself has come more and more to 

be dropped altogether, as not being sufficiently precise or involving ambiguity. 

Biozones and faunizones were seldom, if ever, afterwards mentioned by 

Buckman. He always kept to his earlier unit, the hemera. 

The next step was the grouping of his hemerae into larger divisions or Ages. 

In 1896 he published a paper on the Inferior Oolite of Dundry Hill, near 

Bristol (where William Smith had demonstrated his law of superposition to 

Joseph Townsend and Benjamin Richardson about a hundred years before) 

and in it he gave his Ages the same names as the stratigraphical stages of 

d'Orbigny—Bajocian, Bathonian, &c. In 1898 he submitted another paper to 

the Geological Society, proposing to carry on this usage. The Council pointed 

out, however, that he was using stratigraphical terms in a chronological sense, 

a practice which would lead to confusion, and should be discontinued. It 

was at the behest of the Council of the Geological Society, therefore, that 

Buckman first introduced the dual terminology now in use. 

Freed from the toils of stratigraphical nomenclature, he immediately threw 

himself with zest into the elaboration of what must then have seemed a very 

daring enterprise, the foundation of a time-scale based purely on zoology. 

'If the ammonites are recognized as the best indicators of the faunal sequence', 

he wrote, 'and since the chronological subdivisions depend upon this sequence, then 

the further grouping of the chronological subdivisions must be controlled by the 

zoological affinities of the ammonites. For instance, the shortest geological timedivision 

is a hemera:.that is, the time during which a particular species—generally 

in Mesozoic chronology, of an ammonite—had dominant existence. A longer space 

of time contains so many hemerae; it is at present designated by the very faulty title 

of "an Age"; but it is obvious that, as a hemera depends on the ammonite-species, 

an "Age" must depend on the duration of allied series of ammonite-species ... As 

a family has its periods of rise, of maturity, and of decline (or, in scientific language, 

its epacme, acme, and paracme), so the duration of the Age would be principally 

1 H. S. Williams, 1901, loc. cit., p. 578. 

2 p. 583. 

3 C. Diener, 1918, loc. cit., p. 93 ; and 1925, Grundzuge der Biostratigraphie, p. 230. 

4 Williams gave, incidentally, an entirelv erroneous definition of a hemera (loc. cit., 

P- 583). 

5 S. S. Buckman, 1902, loc. cit., p. 557.

24 

TABLE IV. The Ages of Jurassic Time. 

Mainly after S. S. Buckman, T.A., vol. iv, 1922, pp. 6-13, and vol. v, 1925, pp. 71-8, 

and vol. vii, 1930 (Index) with emendations by E. Neaverson, L. F. Spath, and the 

author. 

(For the upward continuation of this table see p. 546). 

1 

J 

PORTLAND 

BEDS 

KIMERIDGE 

CLAY 

CORALLIAN 

! BEDS 

OXFORD 

CLAY 

CORNBRASH 

AND GREAT 

OOLITE 

SERIES 

42 Titanitan 

41 Behemothan 

40 Pavlovian 

39 Pectinatitan 

38 Allovirgatitan 

37 Gravesian 

36 Physodoceratan 

35 Rasenian 

34 PPrionodoceratan 

1 i 

INFERIOR 

OOLITE 

UPPER 

LIAS 

22 Parkinsonian 

21 Stcpheoceratan 

20 Sonninian 

19 Ludwigian 

18 Canavarinan 

17 Dumortierian 

16 Grammoceratan 

15 Haugian 

14 Hildoceratan 

13 Harpoceratan 

33 Ringsteadian 

j MIDDLE LIAS 12 Amalthean 

32 Perisphinctean 

11 Liparoceratan 

••-- 31 Cardioceratan 

10 Polymorphitan 

30 Quenstedtoceratan 

9 Deroceratan 

29 Kosmoceratan 

28 Proplanulitan 

1 

| LOWER 

8 Oxynoticeratan 

7 Asteroceratan 

LIAS 

6 Microderoceratan 

27 Macrocephalitan 

5 Agassiceratan 

26 Clydoniceratan 

25 ?Oxyceritan ! 

4 Coroniceratan 

3 Vermiceratan 

24 Tulitan 

2 Schlotheimian 

23 Zigzagiceratan 

1 Psiloceratan 

NOTES 

1-6. The first 6 Ages were introduced in 1925, T.A., vol. v, pp. 71-8, to take the place of the two 

Ages Caloceratan and Coroniceratan. They are accepted by Neaverson (1928, Stratigraphical 

Palaeontology) except that he uses Arietitan in place of Microderoceratan. 

24. Below this Buckman placed a Gracilisphinctean Age, based on the rare genus Gracilisphinctes, known 

only from a single species found in the Stonesfield Slate; but the Stonesfield Slate was deposited 

in the middle of the Tulitan Age, as it occurs between the Fuller's Earth Rock and the base of the 

Great Oolite Limestones, which both yield Tulitidae (see Chapter X). 

25. The existence of an Oxyceritan Age distinct from the Tulitan has not been proved, but is inserted 

on the opinion of Buckman. 

28. Synonymous (or rather contemporaneous) with this is the Reineckeian Age, always placed by 

Buckman after it. See Spath, The Naturalist, 1926, pp. 324-5. 

30. Synonymous with this is Buckman's Vertumniceratan Age. Vertumniceras being a rare genus almost 

confined to Yorkshire, it is more useful to retain Quenstedtoceratan, as Spath and Neaverson have 

done. See Spath, The Naturalist, 1926, p. 324. 

34. The separate existence of a Prionodoceratan Age is far from surely established, as the genus 

Prionodoceras was coexistent with Ringsteadia and at least in England it appears before it (in the 

Sandsfoot Clay). It is inserted here only because so far no other term has been found for the time 

between the Ringsteadian and the Rasenian. Pictonian might be better; but if the Pictonia zone be 

regarded as belonging to the Rasenian, then Prionodoceratan is redundant. 

36 — the hemerae of Aulacostephanus yo and A. pseudomutabilis. 

37. Above this Buckman supposed to be the position of the 'Mazapalitan' fauna of Mexico, but there 

is no evidence (see T.A., vol. iv, 1922, pp. 6-13). 

38-40. The positions of these are according to Neaverson, 1928, Strat. Pal., pp. 373-6. As will be 

explained on pp. 465-6, Buckman misunderstood the stratigraphy of the Upper Kimeridge Clay. 

Pavlovian Holcosphinctean of Neaverson and Buckman (Holcosphinctes being synonymous with 

Pavloiia ; see p. 440). 

42 -- Gigantitan of Buckman, Gigantites Buckman being, according to Spath, a synonym of the earlier 

Tilanites Buckman.

AGES 

governed by the period of acme, and would be less concerned with the epacmastic 

and paracmastic periods of the same family. . . . Following on this again as a logical 

conclusion is the recognition that any time-division larger than an Age must depend 

upon the duration in time of allied ammonite-families.' 

The larger time-divisions he called Epochs. 1 

In the first table (published in 1898) seven Ages and two Epochs were 

introduced to cover the Lias and Inferior Oolite deposits; thus: 

STAGES. 

Bathonian 

Bajocian 

Aalenian 

Toarcian 

Pliensbachian 

Sinemurian 

Hettangian 

Rhetian 

AGES. EPOCHS. 

Parkinsonian \ i_ 

o • • 1 Stepheoceratan 

bonninian ) r 

Caloceratan 

At this time Buckman advocated relegating the Hettangian as well as the 

Rhaetic stages to the Trias and beginning Jurassic time with the Arietidan 

Epoch. However logical this may seem from a purely laboratory study of the 

ammonites, it overrides too many geological considerations to have proved 

acceptable to any subsequent authors. 

The elaboration of the new chronological classification was proceeded with 

apace and extended to embrace the Upper Jurassic, but it was not until 1922 

that a complete table of the whole of Jurassic time was ventured upon. 2 

Buckman now proposed 43 Ages, of which 18 occupied Caloceratan-Parkinsonian 

time, for which he had suggested only 7 Ages in 1898, and for which 

22 are accepted in more recent works (see Table IV, p. 24). The new additions 

resulted from a much finer discrimination in Ammonite identifications and 

a hemeral table growing by leaps and bounds every year. At the same time 

Buckman worked backwards from palaeontology to stratigraphy and, having 

recognized 7 Ages in the Lower Lias, he proceeded to coin new stage-names 

for the deposits to which they were supposed to correspond—Lymian, 

Mercian, Deiran, Raasay an, Wessexian, Hwiccian. 3 Unfortunately he overlooked 

the work of Mayer-Eymar, who had already assigned a series of substage 

names to the Lower Lias (Filderin, Balingin, Rottorfin, Mendin), some 

of them with exactly the same meanings as Buckman's. 4 As there is, moreover, 

difference of opinion regarding the reality of some of the separate Ages upon 

which Buckman's Lower Liassic stages were founded, the new names are not 

adopted here. 

V. T H E L I M I T A T I O N S OF B U C K M A N ' S C H R O N O L O G Y : 

P R A C T I C A L DIFFICULTIES A N D T H E O R E T I C A L CRITICISMS 

Detailed collecting from the Lias and Inferior Oolite, by Dr. W. D. Lang 

on the Dorset Coast, by Prof. A. E. Trueman and Mr. J. W. Tutcher in the 

1 S. S. Buckman, 1898, 'The Grouping of some Divisions of so-called "Jurassic" Time', 

Q.J.G.S., vol. liv, p. 443. z S. S. Buckman, 1022, T.A., vol. iv, pp. 6-13. 

3 S. S. Buckman, 1917, 'Jurassic Chronology, I, Lias\ O.J.G.S., vol. Ixx, pp. 259 et seq. 

4 K. Mayer-Eymar, 1881, Classification internationalc, cZurich, 4 0 ; also 1884 'Die 

Filation der Belemnites acuti. Vierteljahrsschrift der Ziircher Xaturforsch. Gescllsch. (transcribed, 

Q.J.G.S., 1917, vol. lxxiii, p. 283); and repeated in 1888, Tabl. des Terrains, Zurich 4 0 .


Radstock district and South Wales, by Buckman and Mr. L. Richardson in the 

Inferior Oolite from Dorset to the Cotswolds, and by the late Dr. Lee in the 

Hebrides, led to so great an elaboration of the hemeral table that many lost 

patience with Jurassic chronology, and the principles on which it is based are 

frequently discredited. It may, therefore, be apposite to pass in brief review 

the steps by which the long lists were built up and to attempt to analyse their 

meaning. 

For many years Dr. Lang has studied the Lower Lias of the Dorset Coast, 

collecting the ammonites inch by inch through the long and perfect sections 

exposed in the cliffs on either side of Lyme Regis and Charmouth. He has 

proved that, as Hunton and Simpson perceived in Yorkshire nearly a century 

ago, the successive species have a restricted vertical range, and that, although 

their biochrons may have overlapped to a greater or a lesser extent, the successive 

acmes marking the hemerae of the species can be recognized and separated by 

detailed collecting. Thus Dr. Lang has been able to divide up the Lower Lias 

of Dorset into 38 epiboles, each representing the hemera of a certain ammonite 

(see p. 28). These epiboles average between 9 and 10 ft. in thickness, 

but some are much thinner. In the Belemnite Marls, for instance, there are 

13 epiboles, with an average thickness of 5-6 ft. Some of them may be mere 

layers no thicker than the ammonites. The boundaries have to be fixed arbitrarily, 

for the fossils often occur only in thin seams, separated by barren clays, 

which cannot be assigned with certainty to any particular epibole. 

Correlation by means of such minute subdivisions can only be attempted 

where the exposures are exceptionally favourable. But it so happens that 

there are several other localities in Britain where equally detailed work is 

possible and has been carried out with success. The first of these was the 

Radstock district of Somerset, where Mr. Tutcher and Prof. Trueman were 

able to put the so-called 'polyhemeral system* to the test. By carefully 

collecting from numerous quarries they were able to show an almost equally 

detailed hemeral succession, but the details were in many instances different. 

Whole blocks of epiboles appeared which were unrepresented in Dr. Lang's 

sequence, while others recognized by Dr. Lang could not be found. The same 

occurred in the Inner Hebrides, where the Geological Survey collected large 

numbers of ammonites from the Lower Lias in the cliffs of Pabba and Skye 

and submitted them to Buckman. At the same time there was enough general 

similarity to render broad correlations, by means of some dozen zones, an 

easy matter. 

The supporters of the polyhemeral system of correlation, led by Buckman, 

interpreted these facts as indicating that the existing epiboles present at any 

one locality represent only a fraction of the total number of hemerae that 

elapsed during the Lower Lias period. Each locality, they suppose, shows 

epiboles that have been removed from all the other districts by contemporaneous 

erosion, and consequently the geological record is far more incomplete 

than was imagined. If this is true, we can only hope to build up anything 

like a complete succession by piecing together the fragments that have come 

down to us in separate localities—a process involving many dangers, since it 

depends largely on preconceived notions of ammonite evolution. 

This principle was often summed up by Buckman in favourite axiomatic 

form; for instance 'Different contiguous exposures show faunas of partly or

DISSIMILAR FAUNAS 27 

wholly unlike facies: therefore their faunas are partly or wholly heterochroneous'; 

1 or 'as a proved sequence shows the meaning of dissimilar 

faunas, so dissimilar faunas give reason for expecting heterochroneous deposition'. 

2 One version was printed on the fly-leaf of Type Ammonites 

(vol. iii) for all to ponder who opened the cover: 'Additions to fauna decrease 

the imperfection of the zoological, but increase that of any local geological 

record: the gaps caused by destruction stand revealed more plainly.' It 

was, in fact, the very key-note of Buckman's teaching. Let us, therefore, 

examine the foundations on which it is based. 

When Buckman states that, if two areas are on the same latitude and a fauna 

is well developed in one and absent in the other, the deposits are not contemporaneous 

(synchronous), 3 he is assuming that the fauna in question 

(usually by 'fauna' he means an assemblage of ammonites or even only one 

ammonite species) was ubiquitous during the period of its acme; further that 

it attained its acme for all practical purposes simultaneously in every part of 

the area of its distribution. 

The validity of this assumption has been challenged on various grounds, 

and when the facts of animal ecology at the present day are taken into consideration 

it seems to have little justification. An elaborate attack has been 

directed by Prof. L. D. Stamp, who has marshalled all the facts he can find 

to show how the local distribution of the faunas at present inhabiting the seabed 

is governed by the depth, salinity and temperature of the water, the nature 

of the bottom, the direction of the currents, the availability of food, and .all 

the other familiar ecological conditions making up a suitable or an unsuitable 

environment. 4 Without recapitulating all his arguments, it can be said that 

Prof. Stamp's thesis amounts to this: that observed dissimilarity of fossil 

faunas can be explained by reference to the partial distribution of marine 

organisms at the present day. 

This claim makes a ready appeal to the biologist and more especially to the 

beginner in geology, who may have come to the subject fresh from a study of 

biology. It is, however, an impertinence to suppose that such obvious considerations 

as Prof. Stamp enumerates have not received attention from the 

field-palaeontologists. As Dr. Lang, in restrained language, replied in their 

defence, the palaeontologists have always kept the possibility of reconstructing 

the conditions under which the fossils lived in the forefront of their investigations. 

5 How otherwise could they hope to detect a facies fauna and to select 

the fossils of value in making their correlations ? 

In the course of an argument with Buckman over his insertion of an excessive 

number of hemerae into the time-table of the Corallian rocks, I attempted 

to justify my view (which I still hold) that many of his hemeral indices lived 

side by side on the same sea-bed, by reminding him of Lyell's principle that 

the present is a key to the past and instancing the sporadic distribution of 

many modern sea-shells around our coasts. He caused considerable provocation 

by remarking with a smile 'Ah! So you have been reading Lyell: a most 

misleading book'. At the time there seemed no more to be said, so outrageous 

was the heresy. But the remark often recurred to me and I realized that in 

1 S. S. Buckman, 1917, loc. cit., p. 259. 2 Ibid. 3 Ibid., p. 278. 

4 L. D. Stamp, 1925, P.G.A., vol. xxxvi, pp. 11-25. 

5 W. D. Lang, 1925, in discussion of Stamp's paper.

FAUNIZONES. 

DAVOEI 

IBEX 

JAMESON I 

RARICOSTATUM 

28 

TABLE V. Ammonite Epiboles Determined in the Lower Lias. 

EPIBOLES 

DORSET 

W D. LANG. 

Oistoceras spp. 

striatum 

latcecosta 

centaurus 

actceon 

maugenesti and valdani 

masseanum 

pettos 

jamesoni 

obsoleta 

brevispina 

polyntorphus 

Tetraspidoceras spp. 

peregrinum 

taylori 

leckenbyi 

exheeredatum 

OXYNOTUM lymense 

OBTUSUM 

SEMICOSTATUM 

BUCKLANDI 

ANGULATUM 

PLANORBIS 1 

raricostatoides 

ceneum 

obesum and armatum 

| bispinigerum 

densinodulum 

i 

1 

stellare 

landrioti 

plamcosta 

obtusum 

capricornoides 

turneri 

birchi 

hartmanni 

brooki 

sulcifer 

Arnioceras spp. 

alcinoe 

Agassiceras sp. 

s friaries 

Arnioceras sp. 

pseudokridion 

scipionianum 

gmuendense and bucklandi 

rotiforme 

conybeari 

marmorea 

liasicus 

laqueus 

hag enow i 

portlocki 

johnstoni 

planorbis 

EPIBOLES 

RADSTOCK 

J. \Y. TUTCHER and 

I A. E. TRI FMAN. 

| ?brevilobatum 

j latcecosta 

\ Beaniceras sp. 

c/wltiense 

sparsicosta 

actceon 

maugenesti 

ibex 

masseanum 

jamesoni 

obsoleta 

brevispina 

polymorphus 

Phricodoceras 

leckenbyi 

lorioli 

aplanatum (derived) 

macdonnellii (derived) 

raricostatoides (derived) 

zieteni 

subplanicosta 

Gleviceras (derived) 

Oxynoticeras (derived) 

stellare 

planicosta 

obtusum 

turneri 

hartmanni 

alcinoe 

sauzeanum 

scipionianum (derived) 

gmuendense (derived) 

?vercingetorix (derived) 

meridionalis (derived) 

Coroniceras sp. (derived) 

liasicus 

johnstoni 

planorbis 

EPIBOLES 

VALE OK EVESHAM 

A. E. TRUEMAN and 

D. M. WILLIAMS. 

Oistoceras spp. 

brevilobatum 

latcecosta 

Beaniceras sp. 

cheltiense 

sparsicosta 

centaurus 

actceon 

maugenesti (valdani) 

ibex 

?nasseanum 

jamesoni 

brevispina 

Phricodoceras 

nodoblongum 

subplanicosta 

planum 

armatum 

bispinigerum 

densinodulum 

podophyllum 

oxynotum 

bijerum 

lacunata 

subpolita 

denotatus 

stellare 

sagittarium 

obtusum 

turneri 

birchi 

nodulosum 

alcinoe 

sauzeanum 

scipionianum 

gmuendense 

rotator 

conybeari 

angulatum (marmorea) 

liasicus 

megastoma 

johyjstoni 

planorbis 

NOTE: the boundaries between the faunizones are fixed arbitrarily.

THE TIME FACTOR 29 

this particular connexion there was at least a germ of truth in it. It showed me 

that Buckman was not oblivious of ecological arguments such as those adduced 

by Prof. Stamp, but that he did not consider them valid. 

The whole crux of the matter upon which the two schools of opinion differ 

is the factor of time. Ecological studies at the present day take no account of 

time as the geologist knows it. They presuppose a stability of animal distribution 

which the palaeontologist cannot tolerate. Thus it is interesting to notice 

that those who invoke partial distribution to explain faunal dissimilarity in the 

rocks picture the past ages in which the geologist is accustomed to soar without 

restriction as a series of kaleidoscoped presents, rather like a reel of motionpicture 

films, each hemera small and rigid. Prof. Stamp complains that an 

ammonite or a brachiopod would not have time to attain wide distribution 

in 'such a short space of time as a hemera' ; T later he again refers to a hemera 

as 4 a brief space of time'. 2 

The views of the other school are strongly contrasted with this. Prof. 

Trueman believes that 'a hemera must represent some thousands of years', 3 or 

again 'must represent a very long period of time, certainly many thousands of 

years'. 4 Buckman goes farther and says 'What is there to prevent giving to 

a hemera a length of time like a million years'. 5 

Given sufficient time, a floating and free-sw T imming species like an ammonite 

would disseminate its shells, borne along by the wind and the tides after its 

death, over vast areas of the earth's surface. Moreover, the geographical 

barriers, which are the principal factor in the separation of local faunas, 

undergo, in the course of time, removal by erosion and earth-movements, 

thus giving free play to migration. 

Every serious student of palaeontology and geology comes to take this 

extreme slowness of the accumulation of the sedimentary series for granted. 

Buckman put the case characteristically in 1922, three years before Stamp's 

criticisms were made: 

'A hemera, though taken as the chronological unit, must be regarded as a very 

lengthy stretch of time. Migration of Ammonites would be a slow process; but . . . 

the rate of Ammonite migration to that of deposition was like the flight of an aeroplane 

to the progress of brick-laying. 

'Present-day phenomena of deposition or of faunal dispersal are very unsafe 

guides. Geological strata are made by the net result of a constant battle of addition 

versus subtraction, in which are seen, locally, the small, slow victories of addition, 

after many vicissitudes. The same applies to modern faunal irregularities—they 

cannot be true criteria of what the ultimate geological record in the rocks will be: 

they are only records of temporary local phenomena, observed during a length of 

time quite negligible in comparison with the length of a hemera.' 6 

Ammonites are not the only shells capable of wide dispersal in the course of 

a hemera. Prof. Morley Davies has shown by simple arithmetic that even the 

sessile brachiopods are capable of migrating a mile in twenty years during 

their free-swimming larval stages. 7 In this way is explained the extraordinarily 

widespread occurrence of certain forms in thin zones; for instance of 

Homceorhynchia cynocephala in the Scissum Beds, Acanthothyris spinosa in the 

1 L. D. Stamp, 1925, loc. cit., p. 19. 

2 Ibid., p. 23. 

3 A. E. Trueman, 1923, P.G.A.y vol. xxxiv, p. 196. 4 Ibid., p. 206. 

5 S. S. Buckman, 1925, T.A., vol. v, p. 70. 

6 Ibid., vol. iv, p. 24. 

7 A. M. Davies, 1930, loc. cit., p. 235.


garantiana zone, or Cererithyris intermedia at the base of the Cornbrash. Contrasted 

with these, however, are a number of brachiopods of such restricted 

colonial habits that they are worthless for all but local correlation : for instance 

Plectothyris fimbria and a number of others in the Inferior Oolite of the 

Cotswolds, a whole croup of localized Cornbrash species (Ornithella classis, 

O. rugosa, O. foxleyensis, Kutchirhynchia idonca, &c.), and certain notable 

forms in the Upper Jurassic, for example Rhynchonella sutherlandice. From 

such instances it is obvious that brachiopods cannot be used indiscriminately 

for zonal purposes, but that each species has to be considered on its own 

merits. If a widespread spec ies is absent from any locality, its absence may 

lead to the detection of stratal failure; but the absence of the many restricted 

colonial forms means nothing. 

The gist of the argument in favour of the utility of dissimilar faunas for the 

detection of stratal failure may be summed up as follows: A certain species is 

found in remotely separated localities, such as in the Lower Inferior Oolite 

of Dorset and the Hebrides, and it is thus proved to have been of widespread 

distribution and not merely a local form. It is contended that the period of its 

dominance was so long that the species would have had time to penetrate to all 

parts of the sea-bed between the places where it is found, and over a wide 

area beyond, during at least some part of its hemera. If it is absent from any 

area where the lithological facies is the same and there are no obvious impediments 

to its migration (such as coral reefs), then it is contended that the strata 

which would have contained the missing species have been removed by 

erosion. 

The most serious objections to correlating by the poly hemeral system arise, 

not out of the theoretical considerations advanced by what might be termed 

the ecology school, but from the practical results obtained by the fieldpalaeontologists 

themselves, in the course of their collecting in distant regions. 

As, with the aid of the newly acquired refinement in discrimination of species, 

detailed work is extended beyond the classic areas, an increasing body of 

evidence is being collected tending to show that the succession of ammonite 

species is not everywhere repeated in the same order. 

One of the most difficult anomalies to explain was found by the Survey when 

they collected from the raricostatum zone of the Lower Lias in the Island of 

Raasay, in the Hebrides. The beds are here developed much more thickly than 

in England, and they were found to contain a remarkable alternation of Echiocerates 

and Derocerates. At the base was a horizon of Echioceras, followed by 

one of Deroceras, and then another of Echioceras, and finally a second horizon 

of Deroceras at the top. According to Buckman's interpretation these horizons 

represent four distinct hemerae, and he endeavoured to show that each could 

be correlated with the so-called raricostatum or armatum zones of some locality 

in England, and that therefore these zones were of different dates in different 

places. 1 With this view Prof. Trueman and Miss Williams are in agreement. 2 

An alternative explanation, however, which Prof. Morley Davies advances, is 

that the Echiocerates and Derocerates merely migrated to and frc; or as he 

puts it 'that dispersal was slow in relation to species-duration—probably 

1 S. S. Buckman, 1914, T.A., vol. ii, p. 96 c, and in Lee, 1920, f Mes. Rocks of Applecross, 

Raasay and N. E. Skye\ Mem. Geol. Surv., pp. 82-3. 

2 A. E. Trueman and D. M. Williams, 1925, Trans. Roy. Soc. Edinburgh, vol. liii, pp. 732-6.

PRACTICAL AND THEORETICAL DIFFICULTIES 31 

owing to climatic checks of a temporary or recurrent kind'. 1 Some such 

explanation is also preferred by Dr. Spath. 2 

Dr. Spath has drawn attention to far more serious anomalies resulting from 

the work of Bovier in the Sinemurian (Lower Lias) near Champfromier, in the 

Department of Ain, and by Burckhardt in the Lower Lias of Mexico. If 

the identifications of these observers are to be relied upon, the epiboles at 

those places are arranged in entirely different order. Dr. Spath gives the 

following table for comparison of the ammonite sequence at Champfromier 

with that established in England; for the purpose of comparison five species 

common to the two areas are selected: 3 

{a) Buckman's 12 hemerae of (b) Champfromier, Beds 2-13. 

the Oxynoticeratan Age. (E. Bovier). 

1 i 3 . . . . . . 

k 12. simpsoni 

j 11. bifer 

i 10. . 

h 9. . . . 

g 8. . . . 

f. oxynotum 7. lacunata 

e. bifer 6. . . . . 

d. simpsoni 5. gagateum 

c. gagateum 4 

b. lacunata 3. oxynotum 

a 2 

The species in the Champfromier column are placed in the order of their 

acmes—representing the hemerae of the species—but the total ranges (biozones) 

are much greater. Thus O. oxynotum ranges up into Bed 13. 

If, as Dr. Spath believes, these results are soundly established, they prove 

(what might have been expected) that the ascertained acme of a given species 

was a local event depending on favourable local conditions. Three species 

may have attained their acmes in one basin of deposition in the order A-B-C, 

in another in the order C-B-A, and another B-A-C, in another C--A-B, in 

another B-C-A, in another A-C-B. Such possibilities cut at the roots of 

polyhemeral chronology, for if the hemera, founded on the acme of a species, 

is likely to have occurred at,different times in different places, it is clearly 

useless as a time-unit. Epiboles therefore lose their value in correlation over 

all but short distances. 

The results obtained at Champfromier are not surprising when we come to 

examine the idea of the acme of a species, upon which the hemera is based. 

There is no evidence that the visible acme in any district corresponds even 

approximately with the complete acme of the species, in the total area over 

which it migrated. Still less does it bear any constant relation to the total 

range, which is the only concrete and sometimes determinable quantity. 

Almost invariably the species perforce chosen as hemeral indices are unrelated 

to those either above or below. They appear upon the scene without antecedents 

and disappear as suddenly, leaving no immediate descendants behind 

1 A. M. Davies, 1930, P.G.A., vol. xli, p. 239. 

2 L. F. Spath, 1931, Geol. Mag., vol. lxviii, p. 184; and 1924, P.G.A., vol. xxxv, p. 190. 

3 L. F. Spath, 1931, loc. cit., p. 184, where full references are given.


them in the succeeding strata. Now, unless all these species were specially 

created and extinguished (if evolution has been continuous), they must have 

had antecedents and descendants somewhere. It is unlikely that every species 

entered our district immediately after it came into existence or left it at the 

moment of its modification to form a new species elsewhere: it is improbable, 

in other words, that every lineage remained in one particular district during 

exactly the time of existence of a single species, no more and no less. Since 

they did not remain longer, we must assume they did not remain so long. 

Therefore all that we can see is a part, and an unknown proportion, of any 

biozone. 

When the epiboles are thus analysed, it is not surprising to find that many of 

the species, which appear to have a restricted range in certain localities, prove 

to have a much longer range—become 'zone-breakers'—when the area of 

observation is extended. 1 Rather, it seems inevitable that they should. It 

follows from the fact that the local acme (epibole) of such a species is only a 

fraction of the complete biozone, that any fraction may be represented in any 

place—the epibole in different places may be on different horizons within the 

much larger biozone. Put in different w r ords, the hemera during which the 

local epibole was formed may represent different parts of the biochron in 

different places. 

Now, in view of this, the fundamental fallacy in the polyhemeral system of 

correlation seems to be, that it takes no account of the probability of several, or 

even any number, of species belonging to unrelated stocks having thrived and 

migrated simultaneously in the same basin. Yet if the Jurassic seas were 

anything like those of the present day, this postulate should be at the forefront 

of any speculations. The paths of the migrating species and stocks would 

intersect in criss-cross fashion as shown in Fig. i, and the order of their 

appearance in any given district would be entirely fortuitous. 

Behind this fallacy there lies confusion of thought in the definition of 

a hemera. The original definitions make no distinction between 'local 

hemerae' and 'ideal hemerae'. From what has just been said it will be evident 

that the two are by no means the same thing. Yet Buckman, on recognizing 

a thin epibole, assumed that the 'hemera' during which it was formed coincided 

with the 'hemera' or time of acme of the species over the whole area of 

its occurrence. As we have seen, such an assumption is quite unjustifiable. 

The two conceptions are so entirely different that there should be two distinct 

time-terms to express them. 

The Germans overcome this difficulty, for they have two different words 

for these distinct concepts. They do not speak of hemerae and epiboles, however, 

but prefer to think in terms of total range, using biozones (of which the 

equivalent time-units, as we have seen, are biochrons). In practice, since 

neither acme nor total range can generally be accurately defined, as has been 

said, the result is the same. The ideal biochron is as elusive as the ideal 

hemera. The visible range at any given places bears no constant relation to 

the complete or absolute total range of the species, considered over the whole 

area of its occurrence. Consequently the Germans do not use the word biozone 

1 'Such species of ammonites, that have shown themselves to indicate a distinct zone in 

certain districts, but transgress the boundaries of that zone in other districts of the same 

zoological province, I call zone-breaking species (zonenbrechende Spezies).'—C. Deiner, 1918, 

loc. cit, p. 113.

TEILZONES 33 

for the visible fragments or parts of biozones with which they usually have to 

deal. For these they have another, an excellent, word—Teilzones. 1 

A Teilzone is a part, and an unknown proportion, of the theoretically 

complete biozone. All so-called 'zones' founded on species unrelated to those 

above or below (that is, on species whose antecedents and descendants are 

unknown) are Teilzones. The term is therefore precisely what we want in 

order to clear up the existing confusion in the use of 'hemerae'. The corresponding 

time-unit would be most logically expressed by some such term as 

'Teilchron'. 

At present almost the whole of our zonal table is built up of these fragmentary 

units or Teilzones, and it is all-important not to lose sight of their 

Mia rat-ion cF 

Lineages A,C.D y 

( 

LOCAUTY I 

E 

K • N O V V N 

LOCALITY Z f 

C&E 

5 A 

LOCALITY 3 

c 

"A 7 " 

MiqraNcn cF 

J-ine^q^s BE. 

V 

NlU 

0


have also been worked out in other formations, using corals, echinoderms, 

gastropods, &c. Lineages are the exception, however, and usually we have to 

do without them in our correlations. In the shallow epeiric seas of North- 

West Europe in Jurrassic times, conditions of life seem to have been normally 

too unstable for any stocks to remain long enough in one place to evolve in situ. 

They continually moved to pastures new. All that we can do is to compare 

the successions of unrelated forms that passed across our different districts 

in the course of their migrations; and let us be under no delusion as to the incompleteness 

and the inadequacy of the record with which we have to deal. 

Before we pass on to other considerations, it may be useful to summarize, 

by means of the following table, the various conceptions and terms which we 

have been discussing. The term 'zone* by itself has now become a kind of 

family term, which may be very ambiguous unless qualified. 

Basis. 

Acme or Duration 

Acme 

Basis. 

Absolute Duration 

Local Duration 

ZONES BASED ON ASSEMBLAGES 

Stratal Term. Chronological Term. 

FAUNIZONE (German SECULE or MOMENT (Zeitmoment 

Faunenzone) or Zonenmoment) 

ZONES BASED ON SINGLE SPECIES 

Stratal Terms. Chronological Terms. 

EPIBOLE 1 HEMERA 1 (Bliitezeit einer Art) 

BIOZONE SPECIES-BIOCHRON (Absolute Lebensdauer 

einer Art) 

TEILZONE TEILCHRON (Locale Existenzdauer 

einer Art) 

There can be no doubt that in practical stratigraphy the old zones or faunizones, 

broad enough to contain a number of epiboles or teilzones, have many 

advantages. In the first place, they accord with the subdivisions universally 

employed in the other systems; in the second place they are frequently all 

that it is possible to recognize or map, and they usually suffice for elucidating 

the structure of a district. For this reason they should be known by all 

geologists, who need not trouble about (and could scarcely memorize) some 

hundreds of local epiboles. Lastly, they do give a tolerably true picture of the 

palaeontological sequence. They will therefore be adhered to wherever 

possible in the stratigraphical part of this book. 

A faunizone, however, as Lange remarks, is nothing more than the sum of 

the biozones of a number of species, and its use is therefore subject to all the 

same reservations and limitations as a biozone. Most of the faunizones with 

which the stratigrapher has to deal are fragmentary—they are only 'faunizoneteilzones', 

made up of bundles of teilzones (see fig. i). 

It is noteworthy that the distinction between faunizones and the smaller 

local units or epiboles, founded on single species, although obvious in a 

1 Since neither definitions nor usage indicate which of the two alternative meanings should 

be attached to the hemera and the epibole, I restrict their use to the only ascertainable values, 

those based on the local or visible acme. It was from these empirical units that Buckman 

built up his 'polyhemeral' tables, and they remain unaffected even though they were assumed 

to be of universal application. It seems more logical to restrict the terms to what Buckman 

actually worked with than to what he thought he was working with.

RELATIVE TIME VALUES 35 

comparatively uniform clay-formation such as the Lower Lias, breaks down 

when we come to deal with strata of more varied lithology. For instance, in 

the Inferior Oolite Series, a varied limestone formation, the smallest subdivision 

that can be made by means of the ammonites (the epiboles) are only 

11 or 12 in number (see pp. 189 and 230). But these subdivisions can be, and 

have been, followed all along the outcrop in the South of England, often 

without finding any specimen of the index-fossil, simply by the general 

assemblage of fossils, with the aid, locally, of the lithology. Such stratal 

divisions answer in every way to the definition of true zones or faunizones. 

Here, therefore, the faunizones and the epiboles are in practice the same thing. 

In the Great Oolite Series ammonites are so rare that they are of little 

account in field-work, but it appears that certain species of Tulites range 

through a thick series of varied deposits. The faunizones, on the other hand, 

are numerous and thin—considerably thinner than the epiboles of the few 

ammonites. The same is true also of the Corallian Beds, where certain 

Perisphinctids range through almost as great a thickness of rock. 

In the Upper Jurassic clays, as in the Lias, the ammonite epiboles are again 

considerably thinner and more numerous than the faunizones. Moreover, as 

in the Lias, lineages can sometimes be recognized. 

From this a general law may be formulated, that in a slowly-deposited clay 

formation the faunizones are much larger than the epiboles, while in varied 

and presumably more rapidly-formed deposits, the epiboles may equal or 

exceed the faunizones in thickness. 

This suggests a means of answering the question: Which changed more 

regularly, the ammonite epiboles or the faunizones, and so which are the more 

satisfactory units for measuring the periods of earth-history? The greater 

thickness of the ammonite epiboles and the greater thinness of the faunizones 

in the more rapidly-formed deposits indicates that migration of the faunal 

assemblages was accelerated, pari passu with the acceleration of deposition, 

relative to ammonite migration. Conversely, the concentration of the ammonite 

epiboles and the spreading out of the faunizones in the clay-formations 

indicates a slowing down of both deposition and general faunal dispersal 

relative to ammonite migration. 

Further, the fact that lineages sometimes occur in clay-formations in such 

a way that several complete successive ammonite biozones (as opposed to 

mere teilzones) appear to be telescoped into a single faunizone, suggests that 

in the clay-periods there was an actual slowing down of general faunal dispersal 

relative to ammonite evolution as well as to ammonite migration. 

It is therefore probably true to say of ammonites that in a very general 

way the frequency in the change of dominant species is some measure of the 

passage of time, even though it can only be gauged by local teilzones. Their 

migrations seem to have been determined by forces largely independent of 

local conditions, and therefore, when they are available, they provide by far the 

best zonal indices. 

VI. OTHER CRITICISMS 

The tables of ammonite sequences which we have been considering, based 

as they are on careful field-work, represent definite and valuable additions to 

knowledge; for even if the restricted vertical distribution of ammonites observed 

in one locality be found to have changed in another, the mere discovery 

854371 D


of this fact is knowledge gained. All such detailed field-investigations carry 

out the sound precept of Quenstedt, that we must get to know our successions 

minutely, as the very first step in stratigraphical geology. It is absolutely 

essential that this work should be undertaken, for until the detailed knowledge 

of the rocks and faunas it provides is available for large areas, generalizations 

are impossible. The task of establishing the palaeontological succession in 

monotonous clay-formations is a thankless one. Those who delight in proclaiming 

that all the results are worthless would therefore do well to keep their 

triumphant tones for more deserving objects. 

Tributes to the value of the results accruing from this detailed work come 

from all parts of the world, and it is clear that without Buckman's chronology 

even general correlation between distant continents would often be impossible. 

The foremost authority on the American Jurassic writes: 'The rocks of the 

American Jurassic are too broken by diastrophism, too discontinuous, too 

poor in fossils, to serve for the working out of the succession except by correlation 

of their parts by comparison with a standard chronology. Buckman's 

biologic chronology provides such a standard.' 1 The work of McLearn in 

Canada points to the same conclusion. 

Hitherto, however, w r e have confined our attention to hemeral tables based 

on actual field-work. Unfortunately other hemeral tables have been propounded 

without the necessary basis in fact, and for such work scorn need not 

be spared. It is one of the greatest misfortunes for Jurassic geology that when 

increasing age and frailty prevented Buckman from continuing active fieldwork, 

he lost sight of the distinction between results obtained with hammer, 

collecting bag and field notebook, and those arrived at by speculation and 

deduction from matrices at home. The extent of the calamity is magnified 

by the fact that this loss of grasp of the importance of keeping surmise distinct 

from fact came when his reputation was at its highest, and the two kinds of 

results are almost inextricably interwoven in his later published works. Only 

those with intimate local knowledge of the English Upper Jurassic rocks can 

hope to distinguish the two. Foreign geologists have been all too ready to 

adopt Buckman's conclusions indiscriminately and an appalling amount of 

error has already been propagated in the world's literature; but they cannot 

be blamed for this. If the following chapters help in some small degree to 

guide future workers to distinguish between fact and fable, this book will not 

have been written in vain. 

That Buckman, who had tramped the Cotswolds and the Sherborne 

country from end to end and knew every quarry intimately, whose earlier 

work was built up solely on sound field-work, could also be the author of his 

last paper on 'Some Faunal Horizons in Cornbrash' 2 and of some of the later 

parts of the fifth and sixth volumes of Type Ammonites, is difficult to believe. 

Without any practical knowledge of the Cornbrash, without describing so 

much as a single section, he proceeded to divide it up into n brachiopod 

zones and coined for it 5 new stage-names. Neither zones nor stages have any 

foundation in fact—one stage ('Hintonian') even brought together Upper 

Cornbrash and Forest Marble (Hinton Sands). The zonal indices represent 

1 C. H. Crickmay, 1931, 'Jurassic History of North America: its bearing on the Development 

of Continental Structure', Proc. Amer. Phil. Soc., vol. lxx, p. 73. 

2 S. S. Buckman, 1927, Q.J.G.Svol. lxxxiii.

OTHER CRITICISMS 37 

no more than a list of the brachiopod fauna of the Cornbrash, enumerated in 

no special order, while the definitions of all the stage-names, without exception, 

are fanciful. 1 

On Buckman's privately-printed work there was not even the check of an 

appointed referee (however lenient) or a publication committee. The immense 

hemeral tables drawn up for the Corallian Beds in volume v of Type 

Ammonites are entirely fictitious. Almost every ammonite hitherto named 

from the Oxford district is supposed to be a separate hemeral index and there 

is no observational backing for the order of succession in which most of the 

species are placed. The method of analysing Blake and Hudleston's paper on 

the Yorkshire Corallian Beds, explained by Buckman, speaks for itself; 2 and 

some of his work on the Portland Beds and Kimeridge Clay was little better. 3 

The more important matters will receive attention in their proper places in 

the ensuing chapters. 

1 For a more detailed examination see J. A. Douglas and W. J. Arkell, 'The Stratigraphical 

Distribution of the Cornbrash, Part I\ 1928, Q.J.G.S., vol. lxxxiv, and Part II, 1932, vol. 

lxxxviii. 

2 S. S. Buckman, 1924, T.A., vol. v, p. 35. For criticisms of Buckman's work on the 

Corallian Beds see Arkell, 1927, Phil. Trans., vol. ccxvi B, and 1929, 'Mon. Corall. Lamell.' 

Pal. Soc.; I have pointed out the absurd results arrived at for the Yorkshire sequence by 

Buckman's juggling with numbered slips of paper, loc. cit., 1929, p. 7. 

3 See L. R. Cox, 1925, Proc. Dorset N.F.C., vol. xlvi, and F. L. Kitchin, 1926, Ann. Mag. 

Nat. Hist. [9], vol. xviii, pp. 499-54.

FIG. 2. Sketch-map showing the present distribution of the Jurassic rocks. 

Black—Jurassic outcropping at the surface or covered only by Pleistocene accumulations. 

Dotted—Jurassic concealed by later deposits or under the sea.

PART II 

THE TROUGHS OF SEDIMENTATION AND THEIR 

TECTONIC HISTORY 

CHAPTER II 

THE GENERAL STRUCTURE OF THE 

TROUGHS 

THE distribution of the Jurassic rocks in the British Isles is shown in 

fig. 2, p. 38. It will be seen that the main outcrop crosses England in a 

broad band from the coast of Dorset to the coast of Yorkshire, wThile a former 

extension far to the north and west is proved by outlying patches in Shropshire, 

near Carlisle, around the basalt plateau of Antrim, in the Inner Hebrides 

and on the east coasts of Sutherland and Ross. South-eastward the system 

passes underground, sweeping round the London Basin into Kent and 

reappearing on the other side of the English Channel in the Boulonnais and 

Normandy, whence it is prolonged southward as a continuous sheet under the 

Paris Basin. 

To what extent this distribution reflects the geography of the Jurassic period 

is a problem upon which many have speculated. The basis of any inquiry 

must be investigation of the following subjects: (1) the nature and configuration 

of the Palaeozoic platform upon which the Mesozoic rocks rest; (2) the 

extent and effects of any subsequent movements or denudations suffered by 

the platform or its covering; (3) the connexion between sedimentation and 

contemporaneous earth-movements, and therefore the nature of those movements 

; (4) the lithological and palaeontological facies of the sediments and the 

distribution of the fauna and flora, involving as accurate a correlation as 

possible of all the surviving occurrences of Jurassic rocks. 

The first three problems will be dealt with briefly in this part, while the 

fourth will form the subject of the next or stratigraphical part of the book. The 

final synthesis, a palaeogeographical restoration, will then be briefly attempted 

in the concluding chapter. 

I. THE PALAEOZOIC PLATFORM ON WHICH THE MESOZOIC 

ROCKS REST 

In the year 1856 R. Godwin-Austen published a remarkable paper, setting 

forth reasoned speculations on the possible extension of coal-basins beneath 

the Secondary rocks of South-East England. He showed especially that the 

anticlinal axis of Artois, in the Chalk to the south-east of the Boulonnais, could 

be traced through the Boulonnais and the anticline of the Weald to the Vale 

of Pewsey and the Mendips. From the occurrence of coalfields to the north 

of this axis at both ends, where it emerges from beneath the Secondary covering 

(the Somerset coal-field in the west and the Franco-Belgian fields in the 

east) he concluded that Coal Measures might be expected to run north of the 

axis all the way across Southern England, and might be bored for with success 

along the Thames Valley. He also prophesied that they would be met with

4o THE STRUCTURE OF THE TROUGHS 

'along and beneath some of the longitudinal folds of the Wealden denudation', 1 

and he complained bitterly that there was not as yet one single boring in the 

South-East of England deep enough to give any certain information concerning 

the Palaeozoic rocks below the Secondary covering. 

This paper aroused general curiosity, and as the result of a realization of the 

economic gain that would accrue if coal seams could be found at a workable 

distance below the Chalk, borings soon began to be undertaken. The first 

were the famous Sub-Wealden borings near Battle, in Sussex (1872-5), which, 

however, unexpectedly proved an enormous thickness of Jurassic rocks and 

were abandoned in Oxford Clay at a depth of 1,605 ft. below sea-level. As is 

now well known, numerous subsequent shafts farther north and east, in Kent, 

struck Coal Measures at workable depth and the economic working of the 

Kent coal-field is now an accomplished fact. The data obtained in the Kentish 

borings and published by the Geological Survey have been of incalculable 

value to theoretical geology and stratigraphy, and most of all to the stratigraphy 

of the Jurassic. 

Immediately after the sinking of the Sub-Wealden shafts a deep boring was 

undertaken at Burford Signet, near Burford, Oxfordshire (1875-7), which 

encountered Coal Measures at a depth of 834 ft. below sea-level or 1,184 ft. 

below the surface of the Great Oolite. This was followed in the late 'seventies 

and early 'eighties by several borings for water in and round London—at 

Meux's Brewery in the Tottenham Court Road (1877), at Streatham (1882) 

and at Richmond (1882-4). These and a number of subsequent sinkings in the 

London area proved Old Red Sandstone and Devonian at depths of from 

900 ft. to 1,100 and even 1,200 ft. below sea-level, without any Coal Measures. 

They thus provided ah explanation of a problematic deep boring for water 

made at Kentish Town as early as 1853, which had passed from Gault into 

red sandstones, supposed by some to be an abnormal development of the 

Lower Greensand and by others regarded as Trias, but which were in fact 

Old Red Sandstone. 2 

Farther north, at Turnford and at Ware, the Palaeozoic platform was reached 

at shallower depths—879 ft. and 686 ft. below sea-level—and at Ware it consisted 

of Lower Palaeozoic strata (Silurian). In 1887 Charnian igneous rocks 

were struck at Bletchley, only 159 ft. below sea-level. This occasioned such 

surprise that the record was for many years misinterpreted; but early in the 

present century the matter was set at rest by two shafts sunk at Calvert, 

Bucks., only 12 miles from Bletchley, which encountered Shineton Shales 

(Cambrian) at almost exactly the same level (153 ft. below sea-level or 443 ft. 

below the surface of the Oxford Clay). Still more recently, Silurian has been 

struck again in Buckinghamshire, at Little Missenden, at a depth of —741 ft. 3 

In East Anglia the platform has been reached at Culford near Bury St. 

Edmunds, at three points at and near Harwich (see map, fig. 3, p. 44) and 

at Lowestoft. At all of these places it consists of Lower Palaeozoic rocks 

(Silurian or Ordovician or older), directly overlain by the Cretaceous. 

In the South of England, therefore, there remain only two spaces beneath 

which we know nothing of the Palaeozoic platform. In the more northerly, 

r R. A. C. Godwin-Austen, 1856, QJ.G.S., vol. xii, p. 73. 

2 J. Prestwich, 1856, Q.J.G.S., vol. xii, pp. 6-14. The matter was complicated by Cretaceous 

fossils falling down the hole and being recorded from the lowest levels. 

* A. Strahan, 1916, Sum. Prog. Geol. Surv. for 1915, pp. 43-6.

THE PALAEOZOIC PLATFORM 41 

which runs from the estuary of the Thames north-westward between Ware and 

the Harwich district, the nature of the platform may in the absence of evidence 

be inferred from the nearest borings on either side of it. The other blank 

space concerning which we are ignorant is much larger, embracing all the 

country south-west of a line drawn along the edge of the North Downs from 

Brabourne to Slough and onward to Burford. Here the Palaeozoic floor is so 

deeply buried that, although deep borings have been undertaken, it has never 

been reached. A sinking at Southampton was stopped at 1,168 ft. below sealevel 

without reaching the bottom of the Chalk, w T hile in Sussex the borings 

at Battle and Penshurst reached 1,605 ft- an d r >76o ft. below sea-level without 

passing through the whole of the Upper Jurassic. Even so near the western 

Palaeozoic outcrops as Lyme Regis, on the border of Dorset and Devon, a 

boring started near the base of the Lower Lias was sunk for 1,302 ft. but failed 

to reach the bottom of the Keuper Marl. 1 

The data that are available enable a general idea of the configuration of the 

Palaeozoic platform under the south-eastern counties to be obtained. In 1913, 

in a masterly presidential address to the Geological Society, Sir Aubrey 

Strahan described its relief and presented a contoured map of its surface 

(seep.44). 2 

The information as to the composition of the platform is obviously too 

scattered for the insertion of geological boundaries, but it is possible to make 

the general statement that older rocks take part in its formation towards the 

north. All the borings proved Lower Palaeozoics north of a line running 

somewhere between Ware and Turnford and again at Cliffe and Chilham in 

the extreme north of Kent; a Devonian belt was encountered under London; 

while still farther south, under most of Kent, and again towards the west at 

Burford, Moreton in Marsh and Bradford on Avon, the Carboniferous System 

comes in. As has been pointed out by Dr. Rastall, this arrangement, with the 

older rocks to the east and north, the Devonian to the south and west, and the 

Carboniferous forming all the southern margin, is a mirror-image, as it were, 

of the Plateau of Brabant, around Brussels. 3 

There can be no doubt that the Plateau of Brabant and the London-East 

Anglian Plateau are parts of one and the same massif. To the south of both 

are important coal-basins—in Belgium that of Namur, in England those of 

Kent and, farther west, of Radstock. The Carboniferous rocks of both the 

Namur and the Radstock coal-fields are intensely folded and overthrust. 

Those of the Kent coal-field appear to have suffered less intense distortion, 

but their true disposition is not thoroughly known, although there are certain 

anomalies of dip and bedding which show at least some degree of disturbance. 4 

The junction of the coal-basins and the London-Brabant Plateau is one 

of the most important tectonic boundaries in Europe. It separates the old 

territory of the Caledonian fold-system, termed Palaeo-Europe, from the 

Armorican and Variscan chains thrust against it from the south. The denuded 

remnants of these chains form Meso-Europe, and against them in turn surged 

1 H. B. Woodward and W. A. E. Ussher, 1911, 'Geol. Country near Sidmouth and Lyme 

Regis', Mem. Geol. Survp. 20. 

2 Sir A. Strahan, 1913, QJ.G.S., vol. Ixix. 

3 R. H. Rastall, 1927, Geol. Mag., vol. lxiv, p. 15. 

4 R. H. Rastall, 1927, loc. cit., p. 16. Published information concerning the Coal Measures 

in Kent is scant, owing to commercial secrecy.


the Alpine System, the boundaries of which enclose a tectonically still newer 

territory, Neo-Europe. 1 Thus, as Dr. Rastall has described, 'the plateau of 

Brabant acted as a horst, against which the advancing earth-waves of the 

Armorican-Variscan system broke and expressed themselves as a series of 

folds and overthrusts; the synclinal of Namur; the anticlinal of the Condroz; 

the synclinal of Dinant; . . . the folds of the Ardennes . . . These constituted 

a mountain chain of Alpine type'. 2 

The conception of a mountain mass in this position, arising as late as 

Permo-Carboniferous times, is clearly of profound importance for our reconstructions 

of Jurassic palaeogeography. It bears out in a remarkable way the 

forecasts of Godwin-Austen, who in his map of 1856 marked East Anglia 

north of the Thames Estuary, the Netherlands and most of the North Sea as 

land in the Oolitic period. 3 By the Upper Cretaceous period, how 7 ever, the 

mountain region was completely levelled down and the Gault was everywhere 

deposited over it. How much of it was still above water in Jurassic times is a 

question which constantly recurs in studies on the English Jurassic, and will 

now be briefly considered. 

II. THE ELIMINATION OF THE EFFECTS OF TERTIARY FOLDING: 

THE ORIGINAL RELATIONS OF THE JURASSIC ROCKS TO 

THE PLATFORM 

Before we can hope to obtain any idea of the original configuration of the 

Jurassic sea-bed we have to take into account the changes which it has subsequently 

undergone. How great these changes have been, and how misleading 

can be their effects, was shown by Sir A. Strahan in his well-known 

presidential address, referred to on page 41. 

The discovery of Charnian igneous rocks in the Bletchley boring at so 

shallow a depth as 159 ft. below sea-level showed that an elevated ridge exists 

there below the Jurassic covering, and it was assumed to be a south-easterly 

extension of the ancient complex of Charnwood Forest. Even if the igneous 

rock brought up from the bottom of the boring was only derived from 

boulders, theSe must have been too large to have travelled far, and since they 

cannot have moved upwards, still higher ground would have to be postulated 

in the immediate neighbourhood. Consequently it was assumed that, as 

Professor Kendall put it in 1905, 'the Oxford Clay at Bletchley was simply 

bedded round about and finally over a rocky islet of Charnian igneous rock'. 4 

'The great Charnian ridge which I have shown to extend far to the south-east 

of its exposure at Charnwood', he wrote, 'I regard as the dominant factor in 

determining the deposition of the whole series of rocks from the Carboniferous 

to the Cretaceous. . . . There are many considerations which make it probable 

that portions of this ancient ridge stood actually above water, in late Palaeozoic 

times and right through the secondary period up to the time of the deposition 

of the Chalk.' 5 

In spite of this, Prof. Kendall mentioned that he suspected the presence of 

lower portions of the Jurassic Series than might have been supposed from the 

1 H. Stille, 1924, Grundfragen der vergleichenden Tektonik, p. 232. 

2 R. H. Rastall, 1927, loc. cit., p. 13. 

3 R. A. C. Godwin-Austen, 1856, loc. cit., map facing p. 46*. 

4 P. F. Kendall, 1905, Final Report to the Royal Commission on Coal Supplies, p. 196. 

5 Ibid., p. 197.

ELIMINATION OF TERTIARY FOLDING 43 

accepted record of the Bletchley boring; indeed less than 5 miles away, two 

borings at Stony Stratford showed a succession of Lias and Oolites. Further, 

he confessed that careful search had not resulted in the discovery of any trace 

of pebbles of foreign rocks of Charnian type in any of the Liassic, Oolitic or 

Neocomian deposits—a very remarkable fact. 

In 1913 Prof. A. Morley Davies put forward a fresh interpretation of the 

Bletchley boring, based on the new shafts at Calvert, 12 miles away in the 

direction of the strike of the Oxford Clay. He was able to show almost conclusively 

that both the Bletchley and the Calvert borings passed through 

Lower Oolites and Lias, and that the Charnian rocks at Bletchley formed part 

of the ancient floor beneath the Lower Lias, corresponding to the Cambrian 

shales in the same position at Calvert. 1 At the same time he published a map 

showing the contours at the base of the marine Jurassic (Rhastic and Lias) in 

this part of England. 

Sir A. Strahan showed in the same year that the ridge at Bletchley was a 

comparatively recent feature, of little account in Jurassic palaeogeography. 

After reducing all the depths at which the platform had been encountered 

in borings to their distance below sea-level, and from this compiling the 

contoured map shown in fig. 3 (p. 44), he proceeded to correct it for post- 

Cretaceous earth-movements. This was done by selecting a convenient 

stratigraphical plane in the Upper Cretaceous rocks, of widespread occurrence 

and uniform lithology, and ascertaining to what extent it has been 

distorted, assuming that at the time of deposition it was approximately 

horizontal. 

The plane selected was the base of the Gault. Its altitude was determined 

at as many points as possible, at the outcrop and from numerous well-records, 

and from the data so collected was constructed a second map, shown in 

fig. 4. Seven contours were drawn at intervals of 500 ft., relative to present 

sea-level, ranging from +500 ft. (above sea) in several districts to —2,500 ft. 

(below sea) in the Hampshire Basin. All the contours below —1,000 ft. were 

estimated from the level of the top of the Chalk as found in borings, and by 

comparison with the thickness of the Upper Cretaceous rocks as developed 

at the nearest outcrops. 

The map so produced represents in a striking way the long E.-W. flexures 

imposed on the Mesozoic rocks in the Tertiary (PMiocene) period, at the time 

of the Alpine orogeny. Their intensity is surprising, even when one is acquainted 

with the great thrust-fault of that date in the Isle of Purbeck. In 

the Hampshire Basin the base of the Gault is show r n to have been forced down 

to a depth of more than 2,500 ft. below sea-level, while in the Wealden 

Anticline, before removal by denudation, it must have stood at not less than 

1,500 ft. above sea-level—a total difference of 4,000 ft. In the London Basin 

the greatest depth attained is probably —1,500 ft. in a small area north of the 

Hog's Back. 

By combining this ingenious map with that showing the present depth of the 

Palaeozoic platform, Sir A. Strahan then proceeded to eliminate all the folding 

subsequent to the deposition of the Gault. The second map showed the 

correction necessary at any point to bring the base of the Gault back to 

horizontality at present sea-level. By applying this correction to the depth 

1 A. M. Davies, in Davies and Pringle, 1913, Q.J.G.S., vol. lxix, p. 333.

FIG. 3. The present depth in feet of the Palaeozoic platform below sea-level in the principal 

deep borings in South-East England, with contour lines drawn on the surface of the platform. 

After A. STRAHAN, 1913, Q.J.G.S.y vol. lxix. FIG. 4. The contour lines in the base of the 

Gault, and thus illustrating the deformation to which the Gault has been subjected. After 

A. STRAHAN, 1913.

FIG. 5. The contour lines on the Palaeozoic platform at the beginning of Upper 

Cretaceous times, assuming that the platform has since undergone the same deformation 

as the Gault. After A. STRAHAN, 1913. FIG. 6. The Mesozoic rocks which rest 

directly upon the Palaeozoic platform in the South-East of England, and illustrating 

the easterly overlap. After R. H. RASTALL, 1925, Geol. Mag., vol. Ixii, p. 211, fig. 2.


of the platform at the same spot, he determined the level at which the platform 

supposedly stood when the Gault was deposited. Thus at Richmond, where 

the base of the Gault lies 1,122 ft. below sea-level, the platform must have 

been depressed by that amount, to — 1,220 ft. from —98 ft.; while at Bletchley, 

where the Gault no longer exists, but where its base is estimated to have stood 

at 700 ft. above sea-level, he argued that the platform must have been raised 

in Tertiary times by that amount, to —159 ft. from —859 ft. All points where 

the Gault rests directly upon the platform are assumed to have lain at sea-level 

(actually sea-bottom) at the time of the Gault, and are represented, when 

corrected, by the figure o. 

From these data Sir Aubrey constructed the third map, fig. 5, showing the 

supposed configuration of the platform at the time of the Albian transgression. 

Some interesting results emerge, the most fundamental being 

'to accentuate the importance of the elevated tract of Eastern England at the expense 

of the Palaeozoic areas of Western England and Wales; for, of course, the general 

tilt of the Upper Cretaceous rocks towards the east has been eliminated, as well as 

the synclines and anticlines. 1 

'The ridge apparently proved by the Calvert and Bletchley borings is no longer 

in evidence. Those places now appear as being situated on the north-western slopes 

of the elevated tract; nor is there any reason to doubt that the same slope extends 

south-westwards towards Burford. . . . Thus the existence of a ridge in the Palaeozoic 

platform is not in itself sufficient to prove the continuation of an ancient axis, 

such as that of Charnwood. On the other hand, the fact that Cambrian rocks constitute 

the platform at Calvert, and the probability that Charnian rocks were reached 

at Bletchley are highly significant of an old line of upheaval.' 2 

Thus Strahan's method presents us with an entirely new picture of the 

Palaeozoic platform beneath the Mesozoic covering of Eastern England at 

the time when the Gault was formed. Under London, the Thames Estuary, 

Essex and East Suffolk to about as far north as Southwold, stood an elevated 

tract of Palaeozoic and older rocks which appears to have been submerged for 

the first time by the Albian transgression. Around it on all sides except the 

east and north-east lay a trough filled with Jurassic and Lower Cretaceous 

sediments. The slope of the trough, as shown by the spacing of the contours, 

was steepest towards the south, in which direction the floor descended to much 

greater depths than elsewhere. Over the Southern Midlands it was comparatively 

shallow and shelved gently. 

If now we wish to correct the picture still further, to show the configuration 

of the platform at the close of Portlandian times, when the marine conditions 

of the Jurassic came to an end, we can arrive at some approximation to the 

truth by stripping off in imagination the Lower Cretaceous and Purbeck 

strata. In late Jurassic and early Cretaceous times there were considerable 

earth-movements—part of the Saxonian movements, which have been more 

minutely studied in North Germany than in this country. Their effects are 

seen in the faulting and gentle folding of the Jurassic rocks under the Cretaceous 

covering in many parts of England (some of the most easily studied are 

the pre-Albian faults in the Upper Jurassic of Ringstead Bay, Dorset, which 

appear in Plate xxi, p. 451). It is impossible to allow for faulting, but where 

depression was marked by sedimentation it becomes measurable, and in 

1 A. Strahan, 1913, loc. cit., p. lxxviii. 

2 Ibid., p. lxxvii.


comparison with the depression that has taken place the effects of the faulting 

are probably so local as to be negligible. Southern England was a region of 

almost continuous sedimentation during the Upper Jurassic and Lower 

Cretaceous (as will be seen in Chapter XVII, where the matter will be discussed 

more fully) and the magnitude of this sedimentation is a measure 

of the depression which the region underwent. 

The thicknesses of strata between the top of the Portland Limestone and 

the base of the Gault in the areas south of the London landmass and to the 

west and north-west of it make an interesting comparison: 1 

L.G.S. 

Wealden 

Purbeck 

Counties to the South. 

Dorset Hants Sussex Kent Wilts. 

200 

2350 

400 

800 

2000 + 

5oo(?) 

490 

2100 

466 

253 

2000 4- 

562 

Counties to the West and 

North-West. 

40 

30 

85 

Berks. 

and 

Oxon. Bucks. Beds. 

TOTAL 2950 33°° + 3056 2815 + IS5 154 320 280 

From these figures it appears that the portion of the floor of the trough 

which by Gault times was the deepest, namely that lying south of the London 

landmass, received its extra deepening after the cessation of normal marine 

sedimentation at the end of the Portlandian; in fact that nearly all the ascertained 

extra deepening is post-Jurassic. But we shall see later that the greater 

thickness of the Upper Jurassic rocks in the deepened area proves the movement 

to have begun actually long before the Cretaceous period. It may be 

significant that the area which suffered such great depression relatively to the 

rest corresponds with the portion of the platform which belongs to Meso- 

Europe, while the more rigid portion to the north is founded on the older 

Palaeo-Europe. 

Six years after Sir A. Strahan's address to the Geological Society on 'The 

Form and Structure of the Palaeozoic Platform', the Society listened to another 

Presidential Address with a kindred theme by G. W. Lamplugh, entitled 'The 

Structure of the Weald and Analogous Tracts'. 2 In this address the president 

summed up the results of the long-continued investigations by him and his 

colleagues of the Survey, Dr. Kitchin and Dr. Pringle, into the Mesozoic 

strata penetrated in the Wealden borings. He showed that, as Topley had 

discovered many years ago, before the borings were started, 3 the Wealden 

anticline is only a superficial structure, imposed on a deeper-seated syncline, 

the syncline being the trough filled with Jurassic strata which we have been 

discussing. The borings are sufficiently numerous to show that each member 

of the Jurassic Series thickens towards the centre of the Weald from both the 

north and the south (see fig. 7). 

Following Topley, but with a far greater body of evidence, Lamplugh then 

proceeded to show that over the trough in other parts of England also, wherever 

the Jurassic sediments are thickest, the Upper Cretaceous beds are arched 

up to form a compensating anticline. When allowance is made for the 

1 Compiled from 'Thicknesses of Strata', Mem. Geol. Surv., 1916. 

2 G.W. Lamplugh, 1919,0 J.G.S.,vol.lxxv. 3W.Topley, 1875,Q.J.G.S.,vol.xxx,pp. 186-95. 

100 

50 

4 

250 

45 

25 

280

S.S.W. 

BEACHYHEAD 

GT.WHITCOMBE COTSWOLDS 

Nr. Gloucester 

Horiiontal scale 

BATTLE &SUBWEALDEN 

Boring 

PEVENSEy ASHBURNHAM ROBERTS BRIDGE 

BURFORD BORING 

{ismilesJtoS.) 

NORTHLEACH SHERBORNE ! LfAFIELD 

"i r'O o E 0 

THE WEALD 

PEN5HURST 

(l5miie$toW.N.W.) 

CRANBROOK 

THE SOUTH MIDLAND5 

PlUCKlEy 

(7 miles to E.S.E.) 

SU170N VALENCE HUCKING BOBBING 

Boring 

CALVERT BORING 

(H miles to N.) 

BIADON ISLIP 0TM00R BRILL AYLESBURY 

NORTH YORKSHIRE 

ROBIN HOOD'S BAY THE MOORLANDS VALE OF PICKERING THE WOLDS 

N. IO°E., StoupeBrow Bickley Ebbewton Knapton Wharram Garrowby PocKlinqton $ io°w 

----- .0~A 

FIG. 7. Sections across the Jurassic rocks in three parts of England, showing the lenticular shape of the sediments filling the trough, and the superposition 

of an anticline in the Cretaceous rocks upon a syncline in the Jurassics. All three sections are on the same scale. The thick vertical lines represent borings. 

After G. w. LAMPLUGH, 1919, Q.J.G.S., vol. lxxv, figs. 2-4. 

SHEERNES5 

Boring


post-Cretaceous tilt already eliminated by Strahan, the general section across the 

Southern Midlands reveals a closely analogous, though flatter, structure, while 

farther north the same arrangement is again seen in the Yorkshire Basin. In 

the Midlands most of the Chalk arch has been removed by erosion, and the 

western side of the Jurassic lens is also missing, but when the lines that can 

be ascertained are carried on, as was done by Lamplugh in the sections 

reproduced in fig. 7, the analogy is unmistakable. In the Yorkshire Basin the 

Palaeozoic platform under the Jurassic area has never been reached by borings, 

but the manner in which the Jurassic formations dip inwards on both sides, 

while the Chalk rises over them from the south until it is truncated by erosion, 

leaves no doubt but that we have there also the relic of a similar structure. 1 

More recently the Mesozoic rocks near the centre of the Paris Basin have 

for the first time been pierced right through to the Palaeozoic platform by a 

boring at Ferrieres, in the anticline of the Pays de Bray, and M. Pierre Pruvost 

has corrected the level of the Palaeozoic platform for post-Cretaceous movements 

by Strahan's method. He points out that the well-known anticline in 

the Cretaceous rocks at the surface, which provides an invaluable glimpse of the 

Upper Jurassics in a region where they would otherwise be unknown, coincides 

with a thickness of Jurassic rocks which is one-third in excess of the thickness 

at Rouen on the south-west and quadruple that in the Boulonnais on the 

north. Below the Pays de Bray the Palaeozoic platform, which was found to 

consist of ancient mica-schist, lies at a depth of 1,010 metres (3,367 ft.) below 

the surface, or 1,200 metres (4,000 ft.) below the base of the Cretaceous, a 

depth greater than at any other point known in the Paris Basin. 2 Here also, 

therefore, the anticline in the Cretaceous rocks is superimposed on a much 

deeper synclinal trough filled with Jurassic sediments. 

Even without the additional evidence from the French boring, Lamplugh 

came to the conclusion that the same cause had operated all along the troughs 

of maximum deposition. He regarded the superficial anticlines as due to 

isostatic recovery of the base of the troughs after the prolonged subsidence 

which had proceeded all through Jurassic times. 'The infilling and sinking 

have gone on for a very long time in apparent association, as if due to comr 

pensative adjustment; but, in all cases, there has been a final recovery which 

was greatest where the deposits were thickest. This recovery implies a shallowing 

of the trough, and may have been due to a stretching of the floor with 

consequent reduction of the curvature.' 3 

The conception of a stretching of the floor seems difficult to reconcile with 

what is known of the Alpine movements—and post-Oligocene and pre- 

Pliocene the major part of the movements in England certainly were, as 

indicated by the Pliocene platform and the relative positions of the Pliocene 

Lenham Beds in Kent and the Oligocene strata in the Isle of Wight and Creech 

Barrow in Dorset. In Dorset there is incontrovertible evidence of lateral 

pressure in the Isle of Purbeck thrust-fault, which resulted from the fracture 

of a steep monoclinal fold. This fold, as Strahan showed, carried the Gault 

1 For an elaboration of this theme as applied to Yorkshire see Lamplugh, 1920, Proc. 

Yorks. Geol. Soc., N.S., vol. xix, pp. 383-94. 

2 P. Pruvost, 1930, Livre Jubilaire, Centenaire Soc. geol. France, vol. ii, pp. 548-9, and 

see also P. Pruvost, 1928, 'Le sondage de Ferrieres-en-Bray', Ann. de VOffice nat. des Combustibles 

liquidesy 3 e ann. 3 e livr., pp. 429-57; alsoi928, R. Acad. Sci.t vol.iS6, pp. 242 and 386. 

3 G. W. Lamplugh, 1919, loc. cit., p. xc.


down under the Hampshire Basin to more than 2,500 ft. below sea-level. 

Compression, then, rather than tension is a force which it is much more easy 

to imagine in operation about this time, and it would seem to be equally 

capable of accounting for the anticlines and synclines. 

The Chalk, Greensand, and Gault covering which spread evenly over 

troughs and landmass alike, when subjected to lateral pressure, would have to 

adjust itself to occupy a smaller area. So far from folding downwards into the 

troughs, as it would have done had ordinary subsidence continued, it would be 

forced upwards by the compression of the Jurassic sediments already filling 

them. By this process the formation of the anticlines is visualized as a bulging 

up from below relatively to the stable landmass under London, rather than 

a regular folding into anticlines and synclines; a conception which was already 

advocated by Prof. Kendall in his Report. 

If this be the correct explanation of the anticlinal structures, there seems to 

be a fallacy in Strahan's method of correcting the depths of the Palaeozoic 

platform by eliminating the effects of Tertiary folding. The method depends 

on the assumption that the platform was folded in harmony with the Cretaceous 

base-line, the two maintaining a constant relationship throughout the 

movements. It would seem, however, that if the anticlines in the Chalk and 

Gault were formed as a result of compression of the troughs which already 

existed beneath, the distance between the surface of the platform and the 

Cretaceous base-line (the Gault) was increased in the process. Thus, when the 

base of the Gault was forced up to 1,500 ft. above present sea-level in the crest of 

the Wealden arch, the Palaeozoic platform below was not necessarily lifted by the 

same amount, but may have been actually depressed in the centre. 1 This consideration 

would very materially alter Strahan's figures, but the effect on his final 

map of the Palaeozoic platform (fig. 5) would be only to lessen the depth of the 

Jurassic trough relatively to the London landmass. His main theme, the existence 

of this landmass surrounded by troughs of deposition, remains unaffected. 

Before leaving the question of the earth-movements to which the Mesozoic 

rocks were subjected in the Tertiary era, and as a corrective against minimizing 

them, it is as well to mention here the large throws of the faults bounding 

the Mesozoic formations in Scotland and the enormous outpourings of basalt 

by which they were covered, as well as the great volcanic activity of Tertiary 

tunes. In the Hebrides the preservation of such small relics of the Mesozoic 

formations as remain is generally acknowledged to be due to their having been 

lowered into favourable positions among the ancient Pre-Cambrian and Cambrian 

floor by faults with throws of 1,000 ft. or more. 2 The whole of the main 

mass of the Mesozoic rocks has been swept away by denudation, and all that is 

left is fragments that were faulted down into the ancient platform beneath. 

Similarly in Eastern Scotland the Jurassic rocks are faulted into contact with the 

Moine Schists, Helmsdale Granite or Old Red Sandstone, by the Great Boundary 

Fault, and all indications of their original position have been lost. 

1 Since writing this I have found that the same criticism seems to have occurred to the 

late Dr. J. W. Evans, who once remarked in the course of a discussion following the reading 

of an unpublished paper by Mr. H. A. Baker, 'The east-and-west foldings of the Wealden rocks 

were secondary structures resulting from the lateral compression and deepening of the basin 

of older rocks in which they lay' (Abstr. Proc. GeoL Soc., 1917, p. 21). 

z G. W. Lee, 1920, 'The Mesozoic Rocks of Applecros, Raasay and North-East Skye', 

Mem. Geol. Surv., pp. 61 -2.

CHAPTER III 

CONTEMPORANEOUS TECTONICS AND THEIR 

EFFECTS ON SEDIMENTATION 

I. EPEIROGENIC OSCILLATIONS A N D SUBSIDENCE OF T H E 

H 

T R O U G H S ; CYCLIC S E D I M E N T A T I O N 

AVING now gained some idea of the configuration of the ancient platform 

below the principal areas of deposition and of the subsequent 

changes for which allowance has to be made, we are in a better position to 

examine the processes by which the troughs came into existence and were 

filled with sediment. The subject for our inquiry is the fact, as Lamplugh 

put it, that across England 'through all the Jurassic Period there existed a 

steadily deepening trough which swept in a bold curve from north to south, 

bulging towards the west, with land not far distant on both sides'. 1 

Before the discovery of the landmass under London Edward Hull wrote 

a long paper demonstrating the south-easterly attenuation of the Jurassic 

formations in Central England, and remarking that if denudation had caused 

the Jurassic escarpment to recede as far back as the present position of the 

Chalk escarpment, very little of the Jurassic strata would be left. 2 He attributed 

this attenuation to increasing remoteness from the assumed source of 

supply of all the sediment in the west and north-west. He little thought that 

as the strata thinned out towards London they were in reality approaching 

another shore-line; that, in fact, they were nearer to land on this side than the 

thick accumulations of the Cotswolds were to the known land on the other. 

There is now no doubt that the south-easterly attenuation remarked by Hull, 

and so conspicuous in the records of the Bletchley and Calvert borings, is 

due primarily to proximity to the London-Ardennes landmass, and there 

are strong indications that sediments were contributed from both sides of 

the trough. Mr. J. G. A. Skerl has found evidence that the minerals of the 

Northampton Ironstone were derived directly from the east or south-east, 

and he even believes that in certain localities the outcrop is not far from the 

mcuths of streams that brought the materials into the sea. 3 I have also shown 

that there seems no escape from the conclusion that the sands of the Lower 

Calcareous Grit in Oxfordshire, Berkshire and Wiltshire, with their small 

lydite pebbles, entered the sea somewhere to the south-east of Oxford. 4 A 

similar source is also probable, in view of their distribution, for the lydite 

pebbles and sands in the Upper Kimeridge Clay and Lower Portland Beds 

(see Chapter XV, pp. 514-15). The same land was still contributing sediment 

in the Wealden period, for Mr. Baker has been able to trace the mouths of 

streams which opened towards the south-west into the Wealden lake in 

East Kent. 5 

The gradual overlap of the successive members of the Jurassic Series and the 

manner in which they overstep on to the London landmass on the south 

1 G. W. Lamplugh, 1919, loc. cit., p. xc. 

2 E. Hull, i860, 'The South-Easterly Attenuation', &c., Q.J.G.S., vol. xvi, pp. 63-81. 

3 J. G. A. Skerl, 1927, P.G.A., vol. xxxviii, pp. 388, 393. 

4 W. J. Arkell, 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, pp. 80-2. 

5 H. A. Baker, 1917, Geol. Mag. [6], vol. iv, pp. 547-9. 

H.-.4371 

E

52 CONTEMPORANEOUS TECTONICS 

side has been demonstrated by the Survey and is well seen in the section by 

Lamplugh (fig. 8). Dr. Rastall has shown the extent of the overlaps and of the 

total overstep for the whole landmass by means of a map (fig. 6). This is, in 

effect, a geological map of the under side of the Mesozoic covering, and it is 

a highly instructive object for study. Now that so many borings have revealed 

what lies beneath the South-East of England, it is evident that the protective 

action of the Cretaceous covering has preserved from erosion far more evidence 

of the relations of the Jurassic rocks to a contemporary landmass than can be 

obtained in any other part of Britain. Nowhere along the margins of the 

western land could sections like Lamplugh's or a map like Rastall's be drawn, 

ROMNEY CLAP 5MEETH 8RA&CURNE HASTlNQ- WALTHAM *mileE.of CANTERBURY TYLER HERNE HE RNE 

MARSH HILL Borinq LEIGH HARMANjOLE HILL (WEJT&lEANl BAY 

j Boring Boring 

s.s.w. 

0 t>. 

WEALDEN 

Horizontal icale 

FIG. 8. Section across Kent from SSW. to NNE., illustrating the manner in which the 

Jurassic rocks overlap one another against the London landmass and are overstepped by 

the Cretaceous. After G.w. LAMPLUGH, 1919, Q.J.G.S., vol. lxxv, fig. 1. 

for the necessary data have been lost. The Cretaceous blanket, which hid 

everything from our forefathers, has since the days of deep borings shown 

itself to be our best friend. 

Of all the many interesting facts which have come to light, that which most 

immediately concerns us here is the evidence of continual movements throughout 

the Jurassic period. As the formations approach the shore, not only do 

they become thinner and the higher beds overlap the lower, but they become 

increasingly interrupted by non-sequences or stratal lacunae of varying extent. 

As has been pointed out by Mr. Baker, there is evidence that in Kent during 

some parts of the Jurassic period denudation was proceeding in the north-east 

near the shore at the same time as deposition in the south-west. 1 

It emerges from a study of the cores of the borings sunk into the deepest 

parts of the troughs, such as those at Battle, Penshurst and Pluckley in the 

Weald, and at Ferrieres in the Pays de Bray, that the facies of the rocks at 

the bottom of the deepest troughs is the same as at the sides. M. Pierre 

Pruvost has shown that at the bottom of the Ferrieres boring, below a covering 

of 4,000 ft. of Jurassic sediments, the Lower Lias begins with a deposit of 

marl containing vegetable fragments, interbedded with limestones yielding 

Hettangian mollusca, the whole having a littoral appearance. 2 Thence upward 

through the w r hole sequence of Jurassic formations the rocks are of the same 

shallow-water or even littoral facies as are met with near the sides of the 

trough in the Boulonnais and in Normandy. In the Bathonian, coral reefs 

1 H. A. Baker, 1917, loc. cit., p. 545. Compare with this the over-confident statement by 

Jukes-Browne in 1911 (and reprinted in 1922) that the absence of Upper Jurassic rocks under 

London was 'unquestionably due to erosion and planation' after Jurassic times and prior to 

the deposition of the Gault {Building of the British Isles, 3rd and 4th editions, p. 277). 

2 P. Pruvost, 1930, loc. cit., pp. 548, 550.

SUBSIDENCE OF THE TROUGHS 53 

were found at a depth of over 2,300 ft. below the base of the Cretaceous— 

a depth at which, as M. Pruvost says, at the bottom of the sea 'clay deposits 

predominate, their thickness is reduced, neritic formations are unknown, coral 

reefs cannot live, and the fauna has special characters determined by the 

absence of light'. The coral reefs, which occur at two levels 1,000 ft. apart in 

the same boring, in the Bathonian and the Corallian, afford absolutely conclusive 

proof of subsidence during Jurassic times, for reef corals cannot grow 

at greater depths than 40 fathoms. The most recent conclusion, which agrees 

substantially with all previous ones, is that the ordinary depth at which coral 

reefs can commence to be built, except in the abnormally clear water of the 

open ocean, is 120-50 ft. 1 Since the whole of the rest of the circumstances are 

opposed to the idea that the water was abnormally clear or that the reefs grew 

in an open ocean, we may safely limit the depth of the sea in the centre of all 

the troughs where fossil coral reefs are found at 120-50 ft. 

If, therefore, we wish to measure the extent of the subsidence in any 

period of Jurassic time, or to compare the relative subsidence over a given 

time in two localities, every bed that maintains a constant facies over a 

sufficiently wide area can be used as a datum-plane in the same way as Strahan 

used the base of the Gault. This principle was extended to various horizons 

in the Jurassic by Lamplugh, who enunciated what might be termed the Law 

of Planes of Horizontality: 

'When a particular bed in a stratified sequence bears evidence of having been 

deposited at the same depth, and at about the same time, over a wide area, it marks 

a plane originally parallel to the sea-level of its period—i.e. a plane of horizontality. 

When several beds of this kind occur at intervals in the sequence and are not parallel 

to each other, we must infer that there has been relative change in the local plane of 

horizontality during the accumulation of the sequence, and we are enabled to 

determine the direction and amount of the change.' 2 

In Yorkshire, of which he was writing, he used the Rhaetic, the Dogger, the 

Millepore Bed, the Grey Limestone, the Cornbrash, the Corallian limestone 

and the Red Chalk, and as many convenient planes can be found in almost any 

sequence. 

If we restore each plane in turn to horizontality, we come at last to the Rhaetic 

Beds, which contain several distinct planes within the series, and provide 

perhaps the most constant and the most widespread, and therefore the most 

trustworthy, guide of all. It is certain that at the beginning of the Jurassic 

period, when the sea first invaded the Triassic salt lakes and the surrounding 

shores, the Rhaetic Beds were spread out over an almost perfectly level plain 

of Triassic marls and sandstones. The only undulations that have been traced 

in the underlying Keuper Marls are wide and low, and the crests (if so they 

can be called) were probably all covered before the end of Lower Rhaetic 

times. 3 But the subsidence which brought in the sea and allowed it to 

penetrate across North Germany and England to the far north of Scotland 

was the first of the long-continued downward movements, which kept pace 

with sedimentation until the troughs had been filled to depths of 3,000- 

4,000 ft. 

1 J. Stanley Gardiner, 1931, Coral Reefs and Atolls, pp. 63-5. 

2 G. W. Lamplugh, 1920, Proc. Yorks. Geol. Soc., vol. xix, p. 383. 

3 L. Richardson, 1904, Q.J.G.S., vol. lx, pp. 356-7.


It is inconceivable that movements of such magnitude and so protracted 

did not exert a profound influence on, even control, sedimentation. In fact 

their importance has in recent years come to be increasingly recognized, and 

a substantial literature has already grown up on the subject. 

So long ago as 1822 Conybeare and W. Phillips remarked on the rhythmic 

manner in which clay is followed by sand and sand by limestone through the 

Oolitic sequence, and on this account it early acquired the name 'Tripartite 

Series'. J. Phillips enlarged on the theme in 1871, pointing out five alternations 

of clay, sand and limestone from the Upper Lias to the Portland Stone. 1 

Woodward remarked that when the rock-succession is examined in more 

detail 'the exceptions are almost as frequent as the rule', 2 and certainly the 

rule does not hold everywhere, for one or more steps are often missing. Nevertheless, 

in the South of England at least, where 'Estuarine' Series do not 

interfere, no one could fail to be struck with the remarkable rhythmic alternation 

of sediments to which Conybeare and W. Phillips and J. Phillips called 

attention. Indeed some of the apparent exceptions, when inquired into over 

a wide area, are found to furnish new instances conforming to the rule, their 

apparent nonconformity having been due to local failure of one of the stages. 

A good instance of this is the Upper Calcareous Grit, which Phillips mentioned 

as an anomalous sand found locally above the Corallian limestone. 

Where the sequence is fully developed the Upper Calcareous Grit is separated 

from the Corallian limestone by up to 40 ft. of clay (the Sandsfoot Clay) and 

is succeeded by an oolite (the Westbury Iron Ore and Ringstead Coral Bed). 

Closer examination of Corallian stratigraphy has revealed, besides this, 

another complete rotation of clay, sand and limestone, within what was 

formerly grouped as one limestone. 3 We can now draw up a fuller list of 

'tripartite' rotations in the Jurassic Series of the South of England than was 

attempted by Phillips: 

SEQUENCE 

Portland Stone 

Portland Sand 

Kimeridge Clay 

Westbury Ironshot Oolite 

Sandsfoot Grit 

Sandsfoot Clay 

Osmington Oolite and T. clavellata 

Beds 

Bencliff and Highworth Grits 

Nothe and Highworth Clays 

Berkshire Oolite Limestones 

Lower Calcareous Grit 

Oxford Clay 

REMARKS 

The Shotover Grit Sands of Wilts, and 

Oxon. in the Upper Kim. Clay may indicate 

another incomplete local rotation, 

the limestone having been removed 

before the deposition of the Lower 

Lydite Bed (see Ch. XIV). 

The Westbury Iron Ore and Ringstead 

Coral Bed are more thickly developed in 

the Boulonnais as the Oolite d'Hesdin 

l'Abbe. 

The sand and clay are only present in a 

few places. 

1 J. Phillips, 1871, Geology of Oxford, pp. 393-4. 

2 H. B. Woodward, 1894, J.R.B., vol. iv, p. 6. 

3 W. J. Arkell, 1927, 'Mon. Corallian Lamellibranchia', Pal. Soc.} p. 6.

Kellaways Rock 

Kellaways Sand 

Kellaways Clay 

Cornbrash 

SEQUENCE 

Main Forest Marble Limestone 

Hinton Sand and Forest Marble 

Bradford Clay and Forest Marble 

Great Oolite Limestones 

Stonesfield Slate Beds 

Fuller's Earth (with argillaceous rock 

bands) 

Inferior Oolite Series 

Upper Lias Sands and Scissum Beds 

Upper Lias Clay 

Marlstone 

Middle Lias Sands 

Middle Lias Clay 

Lower Lias and Rhaetic Beds 

CYCLIC SEDIMENTATION* 

REMARKS 

55 

The sand and limestone are rarely separable, 

but seem to have been so at Kellaways. 

1 Limestone is usually absent 

except as calcareous gritstone. 

This rotation is much interfered with by 

the development of the Forest Marble 

facies, but it is one of Phillips's original 

instances. He included the Cornbrash, 

which can scarcely belong. 

Woodward cites the Fuller's Earth Rock 

as breaking the series, but the 'rock' is 

only an argillaceous stone and occurs at 

various horizons throughout an essentially 

clay series. The intensely sandy 

nature of the Stonesfield Slate Beds is 

best appreciated in the Cotswolds (as 

at Hampen cutting, p. 276). 

The Inferior Oolite Series may contain 

two minor cycles in the Cotswolds 

(Naunton Clay, Harford Sand, Snowshill 

Clay, Tilestone, &c..). 

These may span as much time as several 

of the later cycles. 

It is not suggested that sand, clay or limestone every time overspread the 

whole area of deposition simultaneously. Such a suggestion would be absurd. 

Moreover, it is known that sand often passes laterally into clay and vice versa; 

this is of especially frequent occurrence in the Upper Lias, Lower Calcareous 

Grit and Portland Sand, and is due to sand having begun to be deposited 

earlier in some places than in others. The conclusion is unavoidable, however, 

that for a large part of Jurassic time (not, apparently, at first, there being no 

sand or notable thicknesses of primary limestones in the Lower Lias except 

near the shoreline in the Mendip-S. Wales region) the sediment brought into 

the sea underwent periodic changes; and that in general a rotation from clay 

through sand to limestone is observable. In the relatively clear-water phases 

when limestones were formed, reef corals grew 7 in many parts of the South 

of England on at least six occasions—Inferior Oolite (several times), Great 

Oolite, Berkshire Oolite, Osmington Oolite, Ringstead Coral Bed (representing 

a broken-up reef hidden from view) and possibly the Portland Oolite. 

Probably the time-values of the cycles are enormously different. 

The explanation of these cyclic rotations (in other systems besides the 

Jurassic) was long ago 'furnished', as Phillips expressed it, 'on the simple and 

sure basis of interrupted depression of the sea-bed', 2 though it is only recently 

that the precise mechanism and meaning of the movements have been 

1 W. Lonsdale, 1832, Trans. Geol. Soc. [2], vol. iii, p. 260. 

2 J. Phillips, 1871, loc. cit., p. 393.


investigated. Their important bearing on the problems of stratigraphy seem 

to have been first recognized by Andree 1 and elaborated by Kliipfel. 2 

Forms of cyclic sedimentation on a small scale are frequently discernible 

in the Lias and certain other formations consisting predominantly of clay. 

These have been closely investigated in Germany by W. Kliipfel, H. Frebold 

and others. 3 At variable intervals through the series are found bands of limestone 

with the upper surface water-worn and drilled by Lithophaga and other 

boring organisms, or encrusted with oysters. Above such eroded surfaces 

there is a sudden lithological change to clay, and afterwards a gradual passage 

through marl to limestone once more. The limestone bands, being the last 

deposits of each cycle, are called Dachbanke (roof-beds). There are numerous 

modifications of this scheme, and Frebold states that in Germany almost 

every small subdivision of the Lias has its ow r n scheme. Some of the stages 

may be missing, while new kinds of sediment, foreign to the cycle, may come 

in. The changes, however, are seldom so important that the signs of rhythmic 

deposition cannot be recognized in some form or another, and the investigator 

has to accustom himself to the special manifestations peculiar to each 

area or group of strata. 

A common variant, instead of the usual limestone Dachbank, is a thin bed 

crowded with some particular kind of shell, with or without signs of erosion. 

A characteristic form of this is familiar to collectors in the Lower Lias of 

Dorset, namely the beds strewn with thousands of belemnite guards, picturesquely 

called by the Germans 'belemnite battlefields' (Belemnitenschlachtfelder). 

Other beds are composed of ammonite shells, oysters or crinoids. 

A point of fundamental importance, noticed by Kliipfel and confirmed by 

Frebold, is that the Dachbanke and the 'battlefield beds' often accurately 

delimit the faunizones or faunizone-teilzones. Frebold has been able to show 

that most of the ammonites of importance for zonal purposes, excepting 

certain long-ranged forms, do not transgress beyond the Dachbank next above 

them. Each cycle, in fact, corresponds with a faunizone (usually in the form of 

a teilzone). 

From this it follows that the sedimentary cycles and the ecological changes 

which gave rise to the succession of faunizones probably had a common cause. 

And the cause was earth-movement. 

'It seems justifiable to suppose', w T rote Buckman in 1922, 'that crustal 

movements were like the waves of the sea, continuous, widespread and of 

variable magnitude, able to raise even deep-sea formations to within reach 

of denuding agencies.' 4 He was writing as a palaeontologist, seeking only to 

account for the non-sequences which his palaeontological researches had revealed 

to him, but the investigators into sedimentation in Germany have 

strangely re-echoed his views. How many times has Buckman, purely from 

1 K. Andree, 1908, 'Uber stetige und unterbrochene Meeressedimentation, ihre Ursachen, 

sowie uber deren Bedeutung fur die Stratigraphie', Neues Jahrb. fur Min.t &c., Beilage Band 

xxv, pp. 366-42. 

2 W. Kliipfel, 1916, 'Uber die Sedimente der Flachsee im Lothringer Jura', Geol. Rundschau, 

vol. vii, pp. 97-109. 

3 H. Frebold, 1924, 'Ammonitenzonen und Sedimentationszyklen und ihrer Beziehung 

zueinander', Centrablatt fiir Min.y &c., 1924, pp. 313-20; 1925, Ueber cydiscile Meeressedimentation, 

Leipzig; and 1927, 'Die palaogeographische Analyse der epirogenen Bewegungen 

und ihre Bedeutung fiir die Stratigraphie', Geol. Archiv., vol. iv, pp. 223-40. 

4 S. S. Buckman, 1922, T.A.y vol. iv, p. 24.

CAUSES OF CYCLIC SEDIMENTATION 57 

the standpoint of a palaeontologist, reiterated sentences which, if they were 

translated into German, would be indistinguishable from some of Frebold's; 

for example 'Gegeniiber der Zeitdauer der Sedimentation nimmt die Zeitdauer 

der Sedimentationsunterbrechungen einen nicht geringen Umfang 

an'; 1 and again 'Wir erkennen, dass die haufigen Schichtliicken, die durch 

tektonische Bewegungen bedingt sind, nicht etwas Absonderliches, sondern 

etwas Natlirliches sind.' 2 

That each Dachbank and 'battlefield-bed', even when no signs of erosion 

are visible, represents not only a shallowing of the sea but also a prolonged 

pause, seems justifiably deduced by Frebold from the difference between the 

faunas found above and below. He concludes that, during the interruptions 

of sedimentation which these beds mark, the faunas migrated elsewhere, and 

even that some of the more quickly-evolving ammonites became extinct— 

'that their biochrons expired'—before the return of suitable conditions enabled 

them to migrate back again. In other words, the time occupied in the 

completion of each sedimentary cycle, including the interval during which 

there was no deposition, exceeded the biochrons of most of the ammonite 

species. 

Interesting confirmation of this deduction was obtained by Brinkmann in 

his work on the Oxford Clay of Peterborough. 3 He distinguished there two 

kinds of interruptions in the sedimentation, which he called Dachbanke and 

Sohlbanke (he has kindly allowed his drawings of these to be reproduced 

here as fig. 9. The descriptions are appended below). The Dachbanke and 

Sohlbanke consist principally of masses of whole and broken shells, chiefly 

ammonites, but including many lamellibranchs. Veins of differently coloured 

clay pierce the undisturbed clay beneath the Sohlbanke like the burrows of 

boring organisms. In the clays fossils consist almost solely of plankton and 

nekton, showing that they were probably laid down under anaerobic conditions 

in which benthos could not live. With the shallowing of the water 

during the formation of the Dachbanke and Sohlbanke came increased current 

action, bringing with it improved aeration, and the bottom-dwelling lamellibranchs 

swarmed. Owing to his more refined method of zoning, it being 

possible to work with true biozones instead of faunizones or teilzones (as 

explained on p. 33), Brinkmann discovered that the periods of shallow water 

(marked by the Dachbanke and Sohlbanke) correspond with apparent leaps 

in the evolution of the several ammonite stocks. In the intervening clays 

evolution proceeded slowly and regularly. These apparent accelerations he 

surmised must indicate prolonged pauses in sedimentation, the pauses often 

exceeding in length the biochrons of several of his subspecies, which some 

other palaeontologists would call species. 

Analysis of the movements involved in these cycles of sedimentation always 

shows that they were caused by gradual shallowing of the water (raising of the 

sea-bed) followed, after a pause, by relatively sudden deepening (subsidence 

of the sea-bed), after which shallowing began again. The same movements 

were repeated dozens of times and they occurred through the length and 

breadth of the sedimentary troughs of Europe. Frebold has traced the same 

individual cycles, their sharp boundaries marking off the same faunizones, in 

1 Hans Frebold, 1927, loc. cit., p. 240. 2 Idem., 1925, l° c - P- 55- 

3 R. Brinkmann, 1929, loc. cit.


the Middle and the Upper part of the Lower Lias of North-West Germany, 

Swabia, Lorraine and Aveyron in France. 1 They were therefore widespread 

and of epeirogenic origin. 

An explanation of the crustal movements involved has been advanced by 

Stille in numerous papers and finally in his great work Grundfragen der 

FIG. 9. Diagrammatic sections, illustrating the 'roofed' (Dachbank) (A) and 

'floored' (Sohlbank) (B) types of sedimentary cycle in the Oxford Clay of 

Peterborough. 

A B 

2. Brownish, sticky shaly clay, 

gradually passing down into 

1. Greenish clay. 

Sharp boundary (denoting a considerable 

pause in sedimentation). 

6. Pavement of shells, overgrown 

with oysters. 

5. Comminuted shells, coarse 

above, becoming finer below and 

passing downwards into 


3. Brownish clay, penetrated by 

veins of greenish clay, which fade 

downwards. 

2. Brownish sticky shaly clay, 

gradually passing down into 


Sharp boundary, as above 

and so on 

3. Grey-brown shaly clay with 

Nucula shells, which become so common 

towards the base that they form a 

2. Shell bed. 

1. Pavement of ammonite shells. 

Sharp boundary (denoting a considerable 

pause in sedimentation). 

5. Thin breccia of Pseudomonotis, 

passing rapidly into 

4. Grey-brown shaly clay, which 

passes down gradually into 

3 Similar clay with Nucula shells, 

which form a basal 

2. Shell-bed. 

1. Pavement of ammonite shells. 

Sharp boundary, as above 

and so on 

After R. BRINKMANN, 1929, Abh. GeselK Wiss. Gottingen, M.-P.-KIasse, N.S., 

vol. xiii, figs. 23, 24. 

vergleichenden Tektonik. The earth's crust is divided into technically unstable 

and sinking regions or geosynclines and technically stable or rising regions 

or geanticlines. The whole of North-West Europe is, and was in the Jurassic 

period, a large geanticline (Meso- and Palaeo-Europe) upon which continental 

(epeiric) seas occupied shallow troughs. To the south lay the deep 

1 H. Frebold, 1927, loc. cit., p. 229.

CAUSES OF CYCLIC SEDIMENTATION 59 

geosyncline of Tethys, corresponding with what is now Neo-Europe—the 

Alps and the Mediterranean. 

The general tendency of the geanticline was one of gradual elevation. But 

the shallow troughs containing the Jurassic seas acted as small unstable and 

sinking regions within the larger stable unit. These smaller sinking units 

Stille regards as diminutive geosynclines of a special kind, but Dacque and 

Frebold consider that Haug's 'aires d'ennoyage' or 'drowned regions' is a better 

term, less likely to lead to confusion. 1 According to the theory, it was the 

interplay of oscillations set up by the upward-rising larger unit and the 

periodic down-sinkings of the drowned regions or troughs within it that gave 

rise to the cyclic sedimentation. Since it follows that the effects of the same 

causes were contemporaneous in different parts of the same trough, the cycles 

admit of correlation over wide areas. The chief point that remains doubtful 

is whether the sea bed actually rose between the major periodical downsinkings, 

or whether it was merely built up by the accumulating sediment. 2 

II. DIFFERENTIAL MOVEMENTS WITHIN THE TROUGHS: 

'AXES OF UPLIFT 1 

The general subsidence of the drowned areas did not everywhere proceed 

at the same rate. They were crossed at intervals by more stable ridges or 

axes, where sedimentation was slow and interrupted, just as near the margins 

of the landmasses. Relatively to the subsiding sea-bed on either side these 

ridges had an upward tendency, on account of which they have been commonly 

termed 'axes of uplift'. Their effect was to subdivide the troughs into 

a number of more or less separate basins of deposition, and their influence 

locally in inhibiting sedimentation in their vicinity was so marked that they 

early attracted attention. In the ensuing chapters they will be used as guiding 

lines in subdividing the outcrop for purposes of description. By this means 

more naturally defined districts are obtained than by the arbitrary methods 

previously employed (as in The Jurassic Rocks of Britain), when the distribution 

of towns or the modern physiographical features were made the basis of 

the descriptions. The major axes of uplift generally mark off regions distinguished 

by peculiarities of facies, both lithological and palaeontological. 

Research has shown that the axes almost invariably coincide with older 

anticlines in the Palaeozoic rocks beneath, while they are as often indicated 

by subsequent foldlines in the Cretaceous and Tertiary covering above. 

Godwin-Austen already remarked on this in his astute paper on the possible 

underground extension of the Coal Measures, which in this, as in other ways, 

was many years ahead of its time. He wrote: 

'The general law seems to be, that when any band of the earthy crust has been 

greatly folded or fractured, each subsequent disturbance follows the very same 

lines—and that, simply because they are the lines of least resistance. In this way, 

marked physical features in any region become unerring guides as to the character 

and extent of the earliest disturbance which took place there.' 3 

1 E. Dacqu£, 1915, Grundlagen und Methoden der Paltiogeographie, pp. 132-3 ; see E. Haug, 

1900, 'Les geosynclinaux et les aires continentales', Bull. Soc. geol. France, [3], vol. xxviii, 

pp.617-711. 

2 As argued by K. Beurlen, 1927, Neues Jahrb. fiir Min., &c., B. B. lvii, pp. 161-230. 

3 R. A. C. Godwin-Austen, 1856, Q.J.G.S., vol. xii, p. 62.

ySiinqsby^* CF PICKERING| [ 

FIG. IO. Sketch-map of the region of the Market Weighton Axis, showing the westward 

overstep of the Chalk. The deflections in the Chalk and Lower Oolite escarpments 

attributed to the Caistor Axis are also shown. Based on the Geol. Survey 

index map.

DIFFERENTIAL MOVEMENTS 61 

Buckman restated the principle in 1901, in a form which has often been quoted. 

He came to the same conclusion as Godwin-Austen after studying the flexures 

in the Inferior Oolite of the Cotswolds. 

4 An anticlinal axis indicates a line of weakness. A line of weakness, once formed, 

tends to produce subsequent lines of weakness. Therefore the Jurassic lines of 

weakness may indicate former lines of weakness; hence former anticlines; hence 

denudation. There may, then, have been several elevations and several denudations 

on the same lines.' 1 

The English Jurassic area was crossed by a number of these axes, of which 

three rank as of primary importance—the Market Weighton, Vale of Moreton, 

and Mendip Axes—and they serve also to illustrate three different types 

of phenomena. The Market Weighton Axis ran WNW.-ESE. across South 

Yorkshire, effectually separating the Yorkshire Basin from the rest of the 

trough of deposition throughout the Jurassic period. Of all the axes this was 

the most persistent and the most important. It lies on a direct continuation 

of the W T harfe Anticline in the Carboniferous System of the Pennines. 

The next in order of magnitude was the Mendip Axis. This was more 

acutely anticlinal than the Market Weighton ridge, but it dies out rapidly 

towards the east, and although it completely interrupts the continuity of the 

Lias and Lower and Middle Inferior Oolite, it has little or no effect on the 

Upper Jurassic formations outcropping farther east. The Mendip Axis is 

directly traceable to the well-known hogsback of steep periclines in the 

Carboniferous and Devonian rocks forming the Mendip Hills, with a curving 

strike from NW.-SE. to W.-E. (the individual periclines are directed east 

and west). 

The Vale of Moreton Axis is a broader and more complex feature, the investigation 

of which is less straightforward owing to the greater part of the 

Mesozoic evidence having been destroyed by Tertiary erosion. It seems to 

have originally lain across the plain north of the present Oolitic escarpment, 

striking N.-S. from the Warwickshire coal-field down the Vales of Moreton 

and Bourton. All that we now see of it is the roots, as it were, close to the 

margin of the trough, where deposition was defective over a wide area from 

the eastern margin of the Cotswolds to the borders of Oxfordshire and 

Northants. Formerly, however, the N.-S. axis separated two great basins of 

deposition—those of the Cotswolds and Lincolnshire—where the deposits, 

especially of the Inferior Oolite period, are very different. 

In a useful summary of English tectonics, Prof. Morley Davies has 

grouped together some of the leading flexures purely according to their 

directrix, after the classification of the late Professor Lapworth. 2 

Armoricanoid (or Armorican)—those with E.-W. directrix, or varying from NE.- 

SW. to NW.-SE. 

Malvernoid (or Malvernian)—those with N.-S. directrix. 

Charnoid (or Charnian)—those with NW.-SE. directrix. 

Caledonoid (or Caledonian)—those with a NE.-SW. directrix. 

We will now review rapidly the more important axes that cross the Jurassic 

areas, referring very briefly to the evidence for any intra-Jurassic and later 

1 S. S. Buckman, 1901, Q.J.G.S., vol. lvii, pp. 147-8. 

2 A. M. Davies, 1929, in Handb. Geol. Great Brit.t p. 1.


movements along them. Details of the stratigraphical evidence, or at least 

summaries with references to the literature, will be found in the second part 

of the book. The importance of the role which these differential movements 

played in the sedimentation during Jurassic times can hardly be overestimated. 

To facilitate reference I have delineated the principal anticlinal flexures of 

South Central England on the accompanying sketch-map (fig. 15, facing p. 86), 

so as to show the connexion between the Jurassic and earlier and later folds. 

It will be shown also that to a certain extent classification is possible by means 

of the periods of activity. 

A Specimen Axis: The Market Weighton Axis. 

The Market Weighton Axis is the most regular example, as well as the most 

persistent, and serves as a model for understanding the rest. It was rendered 

classic by Prof. P. F. Kendall's masterly treatment in his Report to the 

Royal Commission on Coal Supplies in 1905. 

'The line which I have termed the Wharfe [or Market Weighton] axis', wrote 

Prof. Kendall, 1 Svas a critical zone throughout the Jurassic and much of the 

Cretaceous periods. Most of the formations then deposited display pronounced 

abnormalities of thickness and character when that region is approached either from 

south or north, while for some it constitutes the line of transition or change from 

a northern to a southern type, and in regard to the whole series down to the Lower 

Lias there is unmistakable evidence of drastic and complete denudation immediately 

before the deposition of the Chalk. 

Tn face of coincidences so numerous and so complete it seems impossible to avoid 

the conclusion that we have here a line of repeated movement, an axis of unrest, 

which has operated continuously or with brief intermissions through the greater 

part of the secondary period, its position being in direct alignment with the anticlinal 

axis of the Wharfe. 

'The Lower Lias shows a thinning on the Wharfe axis, such as might be explained 

by the maintenance during its deposition of shallow water conditions, which would 

prevent any great amount of sedimentation; or there might have been, in consequence 

of remoteness from a source of supply, some deficiency of sediment; or, 

again, if the area were undergoing oscillations of level, there might have been 

frequent recurrences of conditions of scour, by which the already formed sediments 

might be winnowed away. 

'The first and last of these seem to me to have been the causes chiefly operative. 

The great prevalence of oyster beds in the neighbourhood of Cave and Market 

Weighton appears to indicate conditions of shallow water which I have not noted 

in the Lias to the same extent elsewhere in Yorkshire, and the thinning of the individual 

zones may not improbably be attributed to scouring. 

'I should interpret the facts to imply a ridge of shallows here maintained by 

oscillations of small amplitude, while to the north over the Cleveland area and to 

the south in the Fen region depression was much more continuous and rapid. 

Tn Middle Lias times this tendency went even further, and . . . over the axis 

itself this formation is actually absent. 

'The Upper Lias was continuously deposited over the ridge, but greatly reduced 

in thickness, so that we may, I think, safely regard the movement as still continuing 

in the same way as in Lower Lias times. 

'The unconformable overlap of the Lower Oolites on to the Lower Lias at Givendale 

may mark an upward movement of that region in post-Liassic times. 

1 P. F. Kendall, 1905, loc. cit., pp. 199-200 (29-30).

THE MARKET WEIGHTON AXIS 63 

'The Lower Oolites again show a most marked reduction when traced from the 

north and south. This reduction is largely, though not entirely, due to the failure 

of the great sediments of the Estuarine beds to reach so far from their source, but 

N 

Unconformity 

NEOCOM I AN 

Unconformity 

KIMERIDGE CLAY 

U neon Form ity 

Un con formi ties 

CORALLIAN 

OXFORDIAN 

FIG. 11. Sections showing the attenuation of the Mesozoic formations as they pass over 

the Market Weighton Axis. After p. F. KENDALL, 1905, Rept. Roy. Commission on Coal 

Supplies. 

(NOTE: at the time this figure was drawn rocks of Corallian age were thought to be absent south 

of the axis, but it is now certain that some are present: see text, p. 419.) 

the marine beds are of less magnitude than in the Cleveland areas and in Lincolnshire, 

and signs of unconformable overlap of the higher beds across the lower are 

traceable at several places in Lincolnshire.' 

Prof. Kendall then proceeds to point out similar reductions in thickness in 

all the Upper Jurassic formations. Even a bed elsewhere so widespread as 

the Cornbrash is entirely absent over the axis and for a long distance on either


side of it (in all for more than 40 miles). More recently additional contributions 

to our knowledge of the anomalies in the stratification of the Middle 

and Upper Jurassic rocks have been made by Messrs. Versey and Beilby and 

by Brinkmann, who extended hither his work on the Oxford Clay and compared 

the phenomena with the attenuation against the coastline in the Baltic 

region. 1 Mr. Beilby has paid special attention to the various components of 

the Inferior Oolite, and he finds that the principal movements took place after 

the end of each deltaic phase, before or with the marine incursions. Moreover, 

if the axes of the uplifts are considered to have lain midway between the 

points where any particular bed disappears when traced from both directions 

along the outcrop, then the successive uplifts did not always follow exactly on 

the same line. He has been able to determine the positions of maximum 

uplift along several subsidiary anticlines, during various parts of the Inferior 

Oolite period. 2 

Axes of Malvernian Trend. 

(I) THE VALE OF MORETON AXIS 

The literature bearing on the Vale of Moreton Axis is more scanty and more 

scattered, having suffered from the want of so able an historian as Prof. 

Kendall; therefore as much relevant stratigraphical evidence as possible has 

been brought together in the appropriate places in the following chapters. 

The first to recognize the existence of the anticline seems to have been 

E. Hull, who stated in 1855 that 

'The valley of Bourton on the Water appears to have originated in the existence 

of an anticlinal traversing its centre from north to south.' 'It appears', he added, 

'that, though the strata of the Cotteswold Hills and the valleys by which they are 

surrounded have a general dip toward the south, yet the district is traversed by 

a series of gentle rolls, with north and south axes, and that the anticlines have produced 

lines of weakness, originating valleys; and the synclinals lines of strength, 

originating headlands.' 3 

He was speaking, however, only of the more recent folds superimposed on 

the Jurassic rocks, and he made no mention of intra-Jurassic movements. In 

his memoir on the Cotswold region 4 he pointed out the easterly thinning of 

the Lias and Inferior Oolite towards Oxfordshire, and implied that it was part 

of the general south-easterly attenuation due to remoteness from the source 

of sediment, to which he drew attention in the paper already quoted. 

The first to recognize differential movements in the neighbourhood in 

Jurassic times appears to have been Judd, who approached the area from the 

opposite direction and found the evidence of attenuation just as striking far to 

the east of the Vale of Moreton, in Oxfordshire. In 1875, he wrote: 

'During a considerable portion of the Jurassic period, the area now forming the 

county of Oxford underwent a far less amount of subsidence than that to the north- 

1 R. Brinkmann, 1925, 'Ober sed. Abbild. epirog. Bewegungen', Nachr. Gesell. Wiss. 

Gottingen, M. Phys. Klasse, pp. 202-28. 

2 E. M. Beilby, 1930, 'The Market Weighton Axis in Middle Jurassic Times', Trans. 

Leeds Geol. Soc., pt. xx, pp. 10-12; see also H. C. Versey, 1929, Proc. Yorks. Geol. Soc.t 

vol. xxi, p. 219. 

3 E. Hull, 1855, 'On the Physical Geog. of the Cotteswold Hills', Q.J.G.S., vol. xi, p. 483. 

4 E. Hull, 1857, 'Geol. Cheltenham', Mem. Geol. Surv., Plate 2.

THE VALE OF MORETON AXIS 65 

east and south-west of it respectively. The consequences of this inequality of movement 

are manifested in the disappearance of some members of the series, the 

attenuation of many others, and the littoral characters presented by nearly all of 

them/ 1 

It was Buckman who saw in the modern anticline of the Vales of Moreton 

and Bourton a revival of a Jurassic and still earlier anticline; and carried away 

by Godwin-Austen's ideas of posthumous uplift along old-established lines 

of weakness, and partly as the result of his own detection of the Birdlip Axis 

in the Cotswolds, he tended to minimize the importance of the Oxfordshire 

evidence adduced by Judd. In his North Cotswold paper of 1901 2 he controverted 

Hull's view of a general south-easterly attenuation hereabouts, contending 

that the Lower Lias was little affected in the neighbourhood of the 

axis. The principal period of activity, Buckman pointed out, was certainly 

from the Middle Lias to the end of Middle Inferior Oolite times. The Lower 

and Middle divisions of the Inferior Oolite, which exceed 250 ft. in thickness 

in the Cotswold Basin, thin out rapidly towards the Vales of Moreton and 

Bourton and in these valleys and that of the Evenlode they are entirely absent, 

Upper Inferior Oolite resting upon Upper Lias. To the north-east they 

thicken again until in Lincolnshire they exceed 125 ft. Similarly the Upper 

Lias, which is 300 ft. thick in the Cotswolds and nearly as thick in the 

Northants-Lincolnshire Basin, is reduced to less than 20 ft. in the Evenlode 

Valley. The Fuller's Earth and Stonesfield Slate also disappear as they 

approach the axis. 

Now to a certain extent these appearances are deceptive, as will be seen by 

reference to the map on p. 207, where I have indicated the southern boundary 

of the Scissum Beds and so of the Lower and Middle Inferior Oolite in 

Oxfordshire and Northants. It will be seen that these formations are not only 

absent over the region of the Vale of Moreton, but also everywhere to the 

south of a line which can be traced in a direction rather east of north-east for 

nearly 50 miles, from Stow on the Wold by Chipping Norton and Towcester 

to a point near High am Ferrers, where the strike of the Oolites changes to 

nearly north. This line seems to indicate approximately the boundary of the 

area of deposition of the Lower and Middle Inferior Oolite—a supposition 

which receives support from Skerl's researches on the minerals of the 

Northampton Ironstone. The gradual return of the missing Inferior Oolite as 

the outcrop is followed northwards is undoubtedly due mainly to the change 

in the strike. A horizontal section through Lincolnshire from Northampton 

shows that after the change of strike the outcrop cuts obliquely across a trough 

of deposition, of which it has been following the margin from the Vale of 

Moreton. 3 In this respect, therefore, the Vale of Moreton area shows no 

more signs of anticlinal uplift than does the Cherwell Valley, or than would 

any valley excavated by denudation south of the line bounding the Scissum 

Beds. 

Moreover, when we come to examine the Upper Inferior Oolite we find 

that, although the Upper Trigonia Grit (garantiana zone) stops short at the 

Vale of Bourton, the Clypeus Grit {truellei and schloenbachi zones), which is 

1 J. W. Judd, 1875, 'Geol. Rutland', Mem. Geol Surv., p. 52. 

2 S. S. Buckman, 1901, Q.J.G.S., vol. lvii, pp. 138-49. 

3 See fig. 47, p. 245-


much thicker, passes on across the 'axis' region and finally comes to an end 

beyond it, somewhere between the valleys of the Evenlode and the Cherwell 

(as shown in the map, p. 207). The Great Oolite Series, Cornbrash and 

Oxford Clay do not seem to show any special features in this region indicative 

of an axis of uplift, beyond the gradual disappearance of the Fuller's Earth and 

Stonesfield Slate, overlapped by the Taynton Stone. Again, however, this is 

only part of a much more general overlap towards the east, continued across 

Oxfordshire into Northamptonshire (fig. 47, p. 245). 

The most convincing indications of anticlinal uplift are perhaps those displayed 

by the Upper Lias. As already stated, this formation is 300 ft. thick 

in the Cotswolds, but thins to 80 ft. along the western side of the Vale of 

Moreton, to 30-40 ft. at Chipping Norton, and 5-12 ft. in the Evenlode 

Valley near Charlbury. It soon thickens again to the east, being already 70 ft. 

thick at Bloxham, before reaching the valley of the Cherwell. But it is 

noticeable that the thinnest records are those farthest south. This is especially 

evident when the records of 5-12 ft. at Charlbury and 20 ft. at Milton under 

Wychwood are compared with the 30-40 ft. at Chipping Norton, some 5 miles 

due north. Bloxham, where 70 ft. is recorded, is still farther to the north, and 

no records of the thickness of the Upper Lias seem to be available farther 

south in the longitude of the Cherwell Valley. It may be hazarded that here 

no greater thickness will be proved than at Chipping Norton. There is, in 

fact, a record of a boring at Wytham, near Oxford, on the same longitude as 

Bloxham but much more to the south, and the thickness proved was rather 

less than at Charlbury. 

Thus it would seem probable that two different types of phenomena 

have been confounded, having all been explained as being 'due to the Vale of 

Moreton Axis'. Certainly some anticlinal appearances in the Corallian near 

Oxford are unlikely to have any connexion with the attenuation of the Lias 

and Inferior Oolite, and I have kept the two phenomena separate by referring 

the Corallian uplift to the elevation of an Oxford Axis, 1 which will be discussed 

later. 

Borings made since Buckman wrote in 1901 have proved that Hull was fully 

justified in his opinion that the Lower Lias also thins out from west to east 

into Oxfordshire, and that this thinning of all the Lower Jurassic formations 

is primarily a part of the general south-easterly attenuation to which he was 

the first to draw attention. A boring at Lower Lemington (Batsford) near 

Moreton in Marsh, 2 proved the Lower Lias to have a thickness of only 418 ft. 

in the centre of the Vale, or, making allowance for subaerial denudation, 

perhaps 500-50 ft. at most. It has thus dwindled to half its thickness at 

Mickleton, in the North Cotswold Syncline, only 7 miles away. Before 

reaching Calvert, in Buckinghamshire, it has halved a second time, until no 

more than 240 ft. remains. 

I would venture to explain this thinning of the Lias and Inferior Oolite as 

due primarily to the relations of the present outcrop to the margin of the 

Jurassic trough of deposition. There seems to have been a shelf of shallows 

hereabouts, projecting from the London landmass, and the present outcrops 

curve south-eastward to meet it. This is cause and effect, for all the formations 

1 W. J. Arkell, 1927, loc. cit., pp. 118-22. 

2 A. Strahan, 1913, Sum. Prog. Geol. Surv. for 1912, pp. 90-1.

THE VALE OF MORETON AXIS 67 

are thinner here than on either side and, in particular, the thick limestone 

mass of the Lower and Middle Inferior Oolite is absent. Much less resistance 

has therefore been offered to subaerial denudation and the retreat of the 

escarpments has been accelerated. 

Nevertheless, the differences between the facies of the Inferior Oolite in 

the Lincolnshire and Northamptonshire part of the trough and that in the 

Cotswold part point to a barrier or 'axis of uplift', like that at Market Weighton, 

partially separating them during the time of deposition. Several facts are 

favourable to the location of this axis along the Vales of Moreton and Bourton. 

In the first place there is the sharp angle in the 4 Scissum Line' (map on p. 207) 

near Stow on the Wold and Bourton on the Water, which suggests that the 

shelf was suddenly terminated at this point. Secondly, there is the fact that 

the individual members of the Inferior Oolite Series in the North Cotswolds 

thin out everywhere towards the Vale of Moreton, their feather-edges 

striking almost due N.-S. (Two are inserted as examples in the map, p. 207.) 

Thirdly, as Richardson has pointed out, the Rhaetic Beds show a number of 

peculiarities about Stratford on Avon. 1 All these facts are highly suggestive 

of uplift along a N.-S. axis passing down the centre of the Vales of Moreton 

and Bourton, perhaps along a prolongation of the main Pennine Axis of 

Derbyshire via the Warwickshire coal-field. Permian rocks, in fact, tongue 

southward to Warwick, only 21 miles north of Moreton in Marsh. What we 

now see on the line of the present outcrop of the Lower Oolites is only the 

roots of such an axis, near the region where it joined the land. Probably the 

part which was comparable with that still to be seen near Market Weighton 

was completely destroyed by erosion during the formation of the Vale of 

Worcester and Warwick. 

No effects of any movements subsequent to the time of the Lower Oolites 

have so far been convincingly demonstrated along the southward prolongation 

of the Vale of Moreton Axis. The Upper Jurassic and Cretaceous rocks seem 

to be unaffected, unless some anomalies in the Corallian near Purton, to be 

discussed later, are partly due to this cause. 2 

(2 & 3) THE MALVERN AND WINCHOMBE AXES 

Two other anticlinal flexures of parallel N.-S. strike call for notice before 

we pass on to others of different directrices. On the west side of the main 

promontory of the North Cotswold hill-mass the map shows another conspicuous 

tongue of Lias penetrating southward into the oolitic hills. This is 

the Vale of Winchcombe. It is complementary, as it were, to the Vale of 

Moreton, though much smaller, and its anticlinal structure was likewise 

pointed out by Hull in 1855. 3 That the folding has affected the Lower Lias 

is proved by the occurrence of strata so low as the obtusum zone near Toddington, 

on the Stow road, 4 but no intra-Jurassic movements have so far been 

shown to have taken place along it. 

1 L. Richardson, 1912, Geol. Mag. [5], vol. ix, p. 25. 

2 Cox and Trueman have suggested {Geol. Mag., 1920, vol. lvii, p. 204) that the overstep of 

the Lower Greensand on to Corallian at Faringdon might be accounted for by posthumous 

movements along this axis, but Faringdon lies 5 or 6 miles east of the line, and the occurrence, 

as we shall see, is better explained in another way. 

3 E. Hull, 1855, loc. cit., p. 483, and 1857, 'Geol. Cheltenham', Mem. Geol. Surv., p. 99, 

fig. 15. 

4 L. Richardson, 1929, 'Geol. Moreton in Marsh', Mem. Geol. Surv., p. 8.


A much more important axis with the same strike is the line of the Malvern 

and Abberley Hills, where Pre-Cambrian and Lower Palaeozoic rocks are 

lifted high above the sea. This line corresponds approximately with the 

boundary between the Palaeozoic and Mesozoic terrains, but the junction 

between them is nearly always a faulted one. Although there are many gaps, 

the eye is carried on southward by the Lower Palaeozoic inliers of May Hill 

(about 7 miles from the southern end of the Malverns) and Tortworth, and 

eventually almost to Bath by the upturned eastern margin of the Bristol coalfield. 

Carboniferous Limestone crops out continuously as far south as Chipping 

Sodbury, and even beyond this Old Red Sandstone and probably still 

FIG. 12. Section from the South Cotswold escarpment to the Bristol coal-field, showing the 

Rhaetic and Lias overlapping the Trias on to the Palaeozoic rocks over the continuation of 

the Malvern Axis. From L. RICHARDSON, 1930, 'Wells and Springs of Gloucestershire', Mem. 

Geol. Surv., fig. 2 

earlier rocks immediately underlie the Mesozoic covering (often directly under 

the Rhaetics) a short distance to the east (fig. 12). The Low r er Lias, moreover, 

here becomes very thin just where the Trias is missing. The unusually 

straight N.-S. alignment of the South Cotswold escarpment from Dursley to 

Doynton is also suggestive of an uplift along the line of strike. The same 

trend is carried on by the Inferior Oolite escarpment south of the Mendips 

to Milborne Port, on the Dorset border, but no actual line can be drawn on 

the map. 

Axes of Armorican Trend in the South of England. 

(I) THE MENDIP AXIS 

The Mendip Hills present a third type of axis, differing somewhat from 

the others. The structure of the chain has been elucidated with great care 

and described by Dr. F. B. A. Welch and others. 1 It consists of four steep, 

elongated domes or periclines, their axes striking E.-W., but arranged en 

echelon at such an angle that a line joining their centres runs almost NW.- 

SE. along the central ridge of the hills. In the core of each pericline Devonian 

rocks are exposed, while the cover consists of Carboniferous Limestone. 

According to Dr. Welch the pressure that gave rise to the folding came from 

the south, and the resistance offered by the syncline of the Radstock coal-field, 

the axis of which ran N.-S. parallel to the Malvern Axis, caused thrusting and 

some over-folding of the Carboniferous strata. 

Part of the Mendip Hills stood above water as an island or a chain of islands, 

1 F. B. A. Welch, 1929, 'The Structure of the Central Mendips', Q.J.G.S., vol. Ixxxv 

pp. 45-76; and 'of the Eastern Mendips', ibid., vol. lxxxviii, 1932.

THE MENDIP AXIS 69 

certainly throughout Lower Lias times, and possibly until the end of the 

Bajocian (Middle Inferior Oolite) or even Vesulian periods. Before the deposition 

of the Vesulian the folded Palaeozoics suffered peneplanation. 

Subsequent downwarping of the Jurassic trough carried any more easterly 

periclines that there may be far down underground, where they are concealed 

beneath thick accumulations of Upper Jurassic rocks which do not seem to 

be affected at all in their passage over the prolongation of the axis. 

Godwin-Austen, in his paper of 1856, joined up the eastern end of the 

Mendips with the Vale of Pewsey and so with the Wealden Anticline and the 

Axis of Artois. Buckman in 1901 took further liberties with it, swinging it 

round farther north, across the mouth of the Vale of Pewsey and northeastward 

almost along the edge of the Chalk Downs. 1 By 1927, however, he 

had changed his mind, for he depicted the eastern extension as straight and 

short, directed due W.-E., under the middle of Salisbury Plain. 2 

Now Dr. Welch has shown how on theoretical grounds it is probable that 

only one half of the structure is visible in the Mendip Hills, while the other 

half, resembling it as a mirror image, lies buried beneath the Mesozoic covering 

to the north-east. The resistance offered by the older Malvernian fold of 

the Radstock coal-field to the northward-advancing Armorican earth-wave, 

which gave rise to the formation of the series of periclines arranged en echelon 

from SE. to NW. on one side, would have produced a corresponding series on 

the east side of the obstacle, arranged from SW. to NE. or ENE. Thus the 

chances are that the general line of the Mendip fold, regarded as a whole, 

extends in a NE. or ENE. direction. 

Theoretical considerations are here entirely borne out by the arrangement 

of the outcrops, as may be seen by a glance at the map (fig. 13, p. 70). Each 

formation, from the Carboniferous Limestone to the Cornbrash inclusive, 

tongues deeply into the next in an ENE. direction, and all the tongues point 

straight at the Vale of Pewsey. It seems logical to follow Godwin-Austen and 

to join up the Mendip fold with the Vale of Pewsey; and no sooner do we do 

so than we are committed to follow him still farther, for the Pewsey monocline 

with its periclinal inliers of Upper Greensand, the Vales of Shalbourne 

and Kingsclere, is continued eastward almost to Farnham, where it joins the 

Peasemarsh or Hog's Back Monocline, the most important structural line of 

the Weald (see fig. 15, facing p. 86). 

The Hog's Back-Vale of Pewsey Monocline involves Eocene strata. It is 

presumably, therefore, due chiefly to an uplift in the Miocene period, as is the 

Purbeck-Isle of Wight Monocline, with which it is roughly parallel. 3 There 

are also definite indications of movement between the Cretaceous and Eocene 

periods. 4 From this it might be supposed that a more or less continuous 

history of uplift could be traced along the axis through the Jurassic period; but 

on the contrary there seems to have been complete absence of differential 

uplift from Forest Marble times until the Lower Cretaceous. 

1 S. S. Buckman, 1901, loc. cit., p. 148. 

2 S. S. Buckman, 1927, Q.J.G.S., vol. lxxxiii, p. 16, fig. 2. 

3 Messrs. Dines and Edmunds have shown that, as in the Isle of Purbeck, there was also a 

certain amount of thrusting at the Hog's Back ('On the Tectonic Structure of the Hog's 

Back', 1927, P.G.A., vol. xxxviii, pp. 395-401). 

4 For a valuable summary of the evidence bearing on this point see H. J. Osborne White, 

1907, 'Geol. Hungerford and Newbury', Mem. Geol. Surv., pp. 43-6.

7o CONTEMPORANEOUS TECTONICS 

The relations of the various Jurassic formations to the axis will be treated 

in greater detail in the ensuing chapters, but, owing principally to the wealth 

of exposures in the vicinity of the Radstock coal-field, more is known of the 

FIG. 13. Sketch-map of the region around Frome and Radstock, where the Jurassic outcrops 

cross the end of the Mendip Axis. {Based on the 1 inch map of the Geol. Survey.) 

detailed movements that took place in Liassic times along several subsidiary 

axes farther north, about Radstock and Keynsham, than of those affecting the 

main anticline. 1 Small movements recurred restlessly along all of these axes 

throughout the deposition of the Lower and Middle Lias. The greatest uplift 

1 J. W. Tutcher and A. E. Trueman. 1925, Q.J.G.S., vol. lxxxi; see below p. 131.

THE NORTH DEVON AXIS 71 

of all, however, took place at the end of Bajocian times, before the Vesulian 

transgression. This uplift was not confined to the Mendip Axis, but affected 

all the Armorican axes in the South-West of England, giving rise to what 

Buckman called the Bajocian Denudation. The last Jurassic uplift of the 

Mendip Axis apparently took place during the deposition of the Fuller's Earth 

(see pp. 261-2) and immediately before. The Fuller's Earth as a whole becomes 

very thin and the middle portion of the formation overlaps the lower; then 

finally, near Whatley it overlaps the Upper Inferior Oolite also and comes to 

rest on the Carboniferous Limestone (see fig. 13, opposite). 

(2) THE NORTH DEVON AXIS 

In his well-known memoir on the Inferior Oolite of Somerset between 

Doulting and Milborne Port, Richardson described a small syncline of 

Bajocian rocks centred at Cole near Bruton. 1 This he named the Cole Syncline. 

Subsequently he drew attention to the continuity of the syncline with 

the conspicuous basin-shaped outliers of Middle and Upper Lias forming the 

hills at the Pennards, Glastonbury Tor and Brent Knoll, the last no less than 

22 miles west of the nearest point on the main outcrop, Lamyatt Hill. 2 The 

Cole Syncline (described in full on p. 195) preserves a small trough of Lower 

and Middle Inferior Oolite, of which the continuations on the north and south 

were uplifted and eroded away by the Bajocian Denudation, so that Upper 

Inferior Oolite (Vesulian) was deposited on Upper Lias. The Middle and 

Upper Lias of the Brent Knoll, Glastonbury and Pennard outliers were 

therefore let down into the low positions which led to their preservation, not 

by Tertiary movements, but between Bajocian and Vesulian times. As pointed 

out by Richardson, this syncline is approximately parallel with the Mendip 

Anticline, and its chief Jurassic period of activity was definitely contemporaneous 

with the principal movement along that anticline. The relics of 

a corresponding trough on the north of the Mendip Anticline may be discernible 

in the outlier of Dundry Hill, between the Mendips and the South 

Wales Anticline. 

Since it is in the nature of a syncline to lie between two anticlines, the next 

step is to inquire whether another anticline bordered the Cole Syncline on the 

south. Evidence of such an anticline—'a well-marked line of weakness' as 

Richardson termed it, 3 —there undoubtedly is, and I propose to use for it the 

name North Devon Axis, following Boyd-Dawkins. 4 

For about 6 miles south of Castle Cary, as will be explained in Chapter IX, 

the Upper Inferior Oolite rests on Upper Lias, while farther south, beyond 

Corton Downs, the Lower and Middle Inferior Oolite return and extend 

through the Sherborne district. This anticlinal structure lies directly on the 

prolongation of Boyd-Dawkins's main axis of North Devon, which probably 

runs approximately along the coast at Minehead, where the lowest beds of 

1 L. Richardson, 1916, Q.J.G.S., vol. lxxi, pp. 495-503. 

2 L. Richardson, 1926, Proc. Somerset Arch. N. H. Soc. [4], vol. lxxii, pp. 73-5. The 

synclinal structure of the Brent Knoll and Glastonbury Tor outliers was pointed out by H. B. 

Woodward in 1887, Proc. Bath N. H. and A. F. C., vol. vi, p. 130. 

3 L. Richardson, 1916, loc. cit., p. 518. 

4 W. Boyd-Dawkins, 1894, 'The Probable Range of the Coal-Measures under Oxfordshire 

and the Adjoining Counties', Geol. Mag., N.S. [4], vol. i, p. 459.


the Lower Devonian exposed on the North Devon-Somerset border come 

to the surface. 

The line is indicated by a long elliptical inlier of Rhaetic Beds at Sparkford 

and Camel, close to the Inferior Oolite escarpment; in fact Rhaetics are here 

faulted up within less than a mile of Inferior Oolite, and not many hundred 

yards from Middle Lias (p. 122). West of this the long Lower Lias and 

Rhaetic escarpment of the Polden Hills, running nearly straight for 30 miles, 

from Charlton Mackrell to near Watchet, at once claims attention. The dip 

here is gentle and the outcrops consequently broad. The nearest tongue of 

Trias, between Somerton and Charlton Mackrell, is probably deceptive, 

owing its existence apparently to the erosion of the River Cary. It is safer to 

continue the anticline through Langport straight for the nearest Devonian 

rocks, which tongue a long way into the Triassic tract as the eastward continuation 

of the Quantocks, until they reach immediately north of Taunton. 

Thence the line is followed easily north-westward through the centre of the 

Quantock Anticline, which probably stood above the Rhaetic and Liassic sea 

as an island, like the Mendips. 1 No Jurassic rocks are seen to overlap the Trias 

on to the Devonian of the Quantocks, but the Rhaetic Beds, which approach 

nearest, diminish greatly in thickness. In the outlier of Chedzoy, near 

Bridgwater, they are 30 ft. thinner than at Puriton, only 3 miles farther 

away. 2 

If we continue the curve of this axis eastward, keeping the same radius 

(slightly longer than that of the Mendip Axis but approximately equal to that 

of the Cole Syncline), it passes directly up the centre of the Vale of Wardour, 

parallel to the great fault which bounds the Vale on the north side. The Vale 

of Wardour Axis in turn loses itself in the Plain north of Salisbury, within 

a few miles of where the new Stockbridge and Winchester folds begin; and 

these carry the same line on into the Weald (see fig. 15). The small gap near 

Salisbury is bridged by the parallel anticline a few miles to the south, which 

is continued from Ports Down by further periclines, at Dean Hill and Bower 

Chalke, almost as far west as Shaftesbury. 3 

There can be little doubt, in view of these facts, that the two principal 

'notches' in the western escarpment of the Chalk, the Vales of Wardour and 

of Pewsey, which owe their existence to denudation acting on approximately 

E.-W. anticlines formed during the Miocene orogeny, are based on much 

older Hercynian axes. A study of the Jurassic rocks shows that the uplifts had 

a curiously intermittent history, for the Vesulian and later formations (except 

the Fuller's Earth) are entirely unaffected, although a somewhat violent uplift 

took place along both axes immediately prior to the Vesulian. Throughout 

the whole Upper Jurassic they seem to have sunk steadily as part of the normal 

trough of active sedimentation, differential movements only recurring with 

the onset of tangential pressure, first in the Lower Cretaceous and again in the 

Miocene periods. 

1 The 'Quantock Isle' of Lloyd Morgan's map of the islands in the Keuper lake, reproduced 

in Jukes-Browne, Building Brit. Isles, 1911, ed. 3, p. 250. 

2 H. B. Woodward and W. A. E. Ussher, 1908, 'Geol. Quantock Hills', Mem. Geol. 

p. 71. 

Surv., 

3 Most of these axes in the Chalk country have been worked out by Osborne White, in 

Mems. Geol. Surv.: see especially the Memoirs for Winchester, Andover, Basingstoke and 

Shaftesbury.

THE WEYMOUTH-PURBECK AXIS 73 

(3) THE WEYMOUTH, PURBECK AND ISLE OF WIGHT AXIS 

A third great E.-W. monoclinal fold across the South of England forms the 

central axis of the Isles of Wight and Purbeck and the Weymouth district. 

This fold was the most intense of all the Miocene disturbances in England; 

the steep northern limb was first inverted and then fractured, resulting in the 

Isle of Purbeck and Ridgeway thrust-fault. The fact that the Hamstead Beds 

of the Middle Oligocene are involved in the folding in the Isle of Wight, as 

are also the Oligocene Beds of Creech Barrow in Dorset, proves that the 

greater part of the movement took place during or after the Miocene period. 

On the other hand, the detailed investigation and mapping of the Eocene 

Beds by Clement Reid showed that considerable upheaval and denudation of 

the Chalk was already in progress in the Eocene period, just as on the Pewsey 

Axis. This is proved by the composition of the Eocene gravels: the Reading 

Beds are largely composed of Chalk flint and Greensand chert, while the 

Bagshot Beds contain in addition chert of Purbeck age. 1 

This axis has been clearly described by Sir A. Strahan, whose intensive 

studies have revealed many features of interest. 2 In the first place, the mapping 

shows the presence of separate subsidiary axes on the north, such as the 

anticline of Chaldon, Poxwell and Ridgeway. All, though roughly in line, are 

not a continuous fold but a series of elongated domes or periclines, like those 

of Dean Hill, Ports Down, Kingsclere and Shalbourne. It is evident that this 

structure is characteristic everywhere, uplift not having operated evenly along 

the whole course of any axis. The Brixton and Sandown Anticlines on either 

side of the Isle of Wight are separate and en echelon (see fig. 15), and so are 

those of Weymouth and Purbeck, though there is no doubt that they formed 

part of one and the same major line of upheaval. 

In the second place Sir A. Strahan was able to show conclusively that these 

axes had undergone a phase of elevation between the Lower and Upper 

Cretaceous periods—that is, before the Albian transgression. At Ringstead 

and Chaldon the evidence for this is so well displayed that it is possible to 

measure the dip of the Upper Jurassic and Wealden rocks and of the Albian 

(Upper Greensand) above them, and so to determine the degree of intra- 

Cretaceous uplift quantitatively; and it constitutes no inconsiderable proportion 

of the total movement. 

From the arrangement of the outcrops around the mouths of the Vales of 

Wardour and Pewsey and the presence of a pebble-bed at the base of the 

Albian, which rests on much-attenuated Aptian sands, there is little doubt 

that movements took place immediately before the Albian along those axes 

also. Pre-Aptian movements are attested by the unconformable relations of 

the thin Aptian sands to the Wealden Beds. 3 

With regard to the question of intra-Jurassic movements along the Weymouth 

Axis we are almost entirely in the dark. The earliest Jurassic sediments 

1 C. Reid, 1896, Q.J.G.S., vol. lii, p. 490. 

2 A. Strahan, 1898, 'Geol. Isle of Purbeck and Weymouth', Mem. Geol. Surv.y pp. 212-29; 

see also his earlier memoir on the Isle of Wight; a paper 'On Overthrusts of Tertiary Date 

in Dorset', Q.J.G.S., vol. li, 1895, pp. 549-62; and 1906, 'Guide to the Geological Model of 

the Isle of Purbeck', Mem. Geol. Surv., pp. 5-12 (new edition, 1932). 

3 H. B. Woodward and C. Reid, 1903, 'Geol. Salisbury', Mem. Geol. Sitrvpp. 34-6.


brought to the surface in the centre of the axis before it runs out to sea near 

Langton Herring belong to the Great Oolite Series (Upper Fuller's Earth). 

As might be expected by analogy with the Upper Jurassic rocks over the 

North Devon Axis, neither this nor most of the subsequent formations so well 

exposed around Weymouth show any signs of disturbance or abnormality of 

any kind. The sections are more complete than any others in England, and 

there can be no doubt that the Weymouth and Purbeck Anticline remained 

for all practical purposes quiescent from Bathonian times onward until the end 

of the Wealden. It is just possible, however, that over the centre of the axis 

the Portland Beds suffered erosion in Purbeck times, for there are pebbles of 

Portland Limestone in the Lower Purbeck Dirt Beds on Portland Island 

(see p. 530). 

The nearest outcrops of Lower Oolitic rocks and Lias, on the coast between 

Bridport and Lyme Regis, are at least 5 miles north of the line of the axis. 

Nevertheless, the Lower and Middle Inferior Oolite are thinner and more 

incomplete on the coast than farther inland towards Beaminster, and they 

contain two pebble-beds, which disappear inland. Buckman attributed in 

addition certain phenomena of the Upper Lias Junction Bed to proximity to 

the axis, but the evidence for this seems rather doubtful, some of the data 

upon which he based his conclusions having been subsequently shown to be 

erroneous. 1 

Farther west the course of the anticline is uncertain, but it seems to have 

abutted against Dartmoor. 

Although the inroads of the sea in Dead Men's Bay have obliterated all the 

Lower Jurassic portion of the Weymouth Anticline, there is still much to be 

learnt from the syncline which separates it from the North Devon Anticline. 

This is broader than the syncline between the North Devon and Mendip 

Anticlines in proportion as the anticline to the south is more acute. The first 

features noticed on consulting the map and running the eye westward along 

the continuation of the Tertiary trough of Hants and Dorset are the long 

tongues of Oolites and Lias which extend westward by Ilminster and Chard. 

The Lower Lias reaches to the longitude of Taunton, which is 4 miles farther 

west than the most easterly Devonian rocks of the Quantocks, on the anticline 

a short distance to the north. Next to claim attention is the still more extended 

outcrop of Upper Cretaceous rocks, which reach almost to the edge of the 

Trias. 2 More especially remarkable is the continuous, even curve of their 

northern margin, which accurately reflects the curve of the North Devon Axis. 

From Melcombe Horsey, in the angle of the Dorset Downs, the curve is continued 

westward with only the most trivial deviations, obviously due to subsequent 

denudation, to the end of the Black Down Hills; these in turn point 

straight into the more northerly of the two main troughs of the Mid-Devon 

Syncline, where the Permian rocks tongue conspicuously into the Culm 

Measure region past Tiverton. The detailed stratigraphy of the Inferior 

Oolite bears witness to the existence of a minor anticline in the Jurassics 

1 See below, pp. 168, footnote. 

2 The marked overstep of the Albian along this line does not, in my opinion, indicate any 

anticlinal pre-Albian uplift, since if Albian rocks were preserved anywhere else so far west 

they would likewise overstep the Jurassics towards the margin of the basin (as towards 

London); rather the preservation of the Albian along this line points to its having been lowered 

in a subsequent (Tertiary) syncline.

THE BIRDLIP AXIS 75 

north of Crewkerne, but the evidence does not suffice for entering its course 

upon the map (for particulars see pp. 192-3). In the continuation of the synclinorium 

in the Culm Measures to westward there are many minor flexures. 

(4) THE BIRDLIP AXIS 

To be classed with the E.-W. axes which we have been discussing, rather 

than with those of Charnian trend, is the Birdlip Anticline in the Cotswolds, 

detected and described in detail by Buckman. This uplift divides the main 

Cotswold basin or trough into two minor synclines, those of Cleeve Hill 

and Painswick. It strikes approximately WNW.-ESE. from near Gloucester 

through Birdlip Hill, thence curving SE. along Ermine Street towards Cirencester, 

where it becomes lost beneath the Great Oolite and later rocks. 

The principal uplift took place during the Bajocian (immediately prior to 

the Vesulian) but there were also movements during the Aalenian. In the 

Vesulian and subsequent epochs of the Jurassic the axis seems to have had no 

influence whatever. 

Movements at earlier times are more easily traceable in the synclines on 

either side than along the axis itself. Thus Richardson has shown that the 

Rhaetic Beds reach a greater thickness than anywhere else in Worcestershire 

along the continuation of the Cleeve Hill-Bredon Hill Syncline, at the end 

of the long tongue of Lias and Rhaetics that extends to Droitwich, between 

the anticline of Birdlip and that of the Vale of Moreton. 1 Opposite the Painswick 

Syncline he has similarly found Very striking evidence of a syncline' 

in the Rhaetic Beds of Chaxhill, Westbury on Severn. 2 But although at 

Denny Hill, 2\ miles north-east of Chaxhill, 'there is evidence of the proximity 

of an anticline', he was unable to determine its exact position. It may 

lie near Lassington, but the evidence is equivocal and long since obscured 3 

(fig. 14). Consequently the axis cannot be localized more accurately than 

between Denny Hill and Wainlode Cliff. As may be seen on the map (fig. 15), 

there seems considerable probability that the Birdlip Axis is either a direct 

continuation of or a side-branch from the Malverns. The Malverns and May 

Hill are not in continuity, but seem to be separated by a synclinal area, where 

Trias and Permian rest on Devonian. 

If we classify by means of the principal periods of activity, as it is here 

proposed to do, the Birdlip Axis falls into line with the E.-W. or Armorican 

group. The NW.-SE. direction seems at first an objection, but it should be 

noted that at least two of the other E.-W. axes, those of the Mendips and 

North Devon, sw T ing NW. at their western extremities; in fact the visible 

portion of the Birdlip Anticline is almost exactly parallel with the western 

extremity of the Mendip Axis, repeating its curve faithfully. It is possible 

that it was deviated southward by the Vale of Moreton Axis. 

When viewed in this new light, the failure of the Birdlip Axis to affect the 

Upper Jurassic rocks is explained. Instead of seeking such effects we look for 

oversteps at the base of the Aptian and the Albian, and for final uplift in the 

Miocene period. East of the Mendip Axis is the notch in the Chalk Downs 

forming the Vale of Pewsey; east of the North Devon Axis lies similarly the 

twin notch of the Vale of Wardour; can it be mere coincidence that the 

1 L. Richardson, 1904, Q.J.G.S., vol. lx,p. 352. 2 Ibid., p. 356. 3 Ibid.,pp. 352-3.

FIG. 14. Sketch-map illustrating the anticlinal and synclinal axes along which 

there is evidence of movements in Keuper-Rhaetic and in Inferior Oolite times. 

Inferior Oolite and later beds dotted; Lias shaded; Rhaetic and earlier beds 

white (boundaries approximate). From L. RICHARDSON, 1904, Q.J.G.S., vol. lx, 

p. 350, 1.

THE MELTON MOWBRAY AXIS 77 

Birdlip Axis has to eastward of it the great angle of the Downs, the incipient 

'Vale' of Wallingford, at the entrance of the Goring Gap? Let us continue 

the curve on the map below Cirencester, swinging it round thence eastward. 

First we come to the tongue of Lower Greensand resting on Corallian at 

Faringdon and Badbury Hill, then to the long overstep of the Gault on to 

Kimeridge Clay through the Vale of the White Horse—protracted perhaps 

because cutting our line at a very low angle—and so to Wallingford. On comparing 

the disposition of the Greensand and Chalk of the Wallingford Gap 

with that in the Vales of Pewsey and Wardour, it seems that the differences 

could be accounted for by supposing that the anticline intersects the strike of 

the rocks much more obliquely and is feebler. Finally, the southerly dip of the 

Marlborough and Berkshire Downs demands an E.-W. anticline north of 

them, and this want the Birdlip Axis as here visualized supplies. 

Beyond this (perhaps even so far) it is rash to speculate, but to my knowledge 

no other axis of uplift passes anywhere near the sharp post-Eocene 

anticline superimposed on a pre-Eocene and post-Cretaceous forerunner at 

Windsor. It may be significant that this lies just where we should draw the 

continuation of the Birdlip Axis in order to make it roughly parallel with 

the adjoining portions of the Vale of Pewsey-Hog's Back fold; moreover, 

the strike of the Windsor Anticline is just in the right direction, E. 15 0 S. 1 

Other explanations of the entrance to the Goring Gap at Wallingford have 

been put forward (see below), but the one here offered applies to the Albian 

overstep in the Vale of the White Horse, the Aptian overstep at Faringdon, 

and the southerly dip of the Chalk Downs of Berkshire, and it has the advantage 

in addition of accounting for the analogous phenomena at the Vales of 

Wardour and Pewsey and at Wallingford by analogous causes. 

(?5) THE MELTON MOWBRAY AXIS 

Perhaps the first feature that strikes the eye on glancing at the geological 

index map of Lincolnshire, Leicestershire and Rutland is the long, narrow 

tongue of Middle and Upper Lias and Inferior Oolite which extends north 

of Melton Mowbray for about 12 miles westward of the general line of outcrop, 

to Wartnaby and Old Dalby. The general strike is NNE.-SSW., but 

at Grantham it changes to NE.-SW. and then, at the extremity of the tongue, 

swings round through 315 0 to due E.-W., to revert equally suddenly near 

Sproxton to its original direction of NNE.-SSW. This at once suggests a 

syncline striking ENE.-WSW., running down the centre of the tongue. 

The connexion of the phenomena with geological structure was proved by 

Prof. A. H. Cox, who investigated the area with a view to tracing the relationship 

between geological structure and magnetic disturbances. He showed 

that an anticline runs south of the Wartnaby and Old Dalby tongue, passing 

along the valley through Melton Mowbray, that the age of the anticline is at 

least as late as post-Triassic, and that it probably 'follows and is founded upon 

the line of an older and more pronounced anticlinal uplift of pre-Permian 

date'. 2 

In a later paper Professors Cox and Trueman stated that the appearances 

1 C. N. Bromehead, 1915, 'Geol. Windsor', Mem. Geol. Surv., pp. 14-15. 

2 A. H. Cox, 1919, Phil. Trans. Roy. Soc., vol. ccxix A, pp. 73-135; and Cox and Trueman, 

1920, Geol. Mag., vol. lvii, p. 198.


'suggest that the movements which gave rise to the anticlinal structure had 

died down during or prior to the deposition of the Bathonian rocks', 1 and 

Dr. Rastall in discussing the anticline goes even farther, saying that 'it seems 

impossible to attribute the whole thing to Tertiary disturbance, since the 

Upper Jurassic strata are not affected'. 2 

Now, examination of the map shows that, although the rocks above the 

Inferior Oolite may show no disturbance over the anticline, they certainly are 

affected by the corresponding syncline. In this respect they agree with the 

Inferior Oolite and Lias, for by examination of the map alone it would be 

impossible to detect the presence of the Melton Mowbray Anticline. It is the 

companion syncline to the north of it that has the conspicuous effect on 

the strike, and here too the Great Oolite, Cornbrash and Oxford Clay tongue 

westward, repeating faithfully the behaviour of the lower formations. The 

Oxford Clay extends past Bassingthorpe at least 5 miles west of the general 

boundary of the outcrop, and it would extend much farther if it were not cut 

off by a small fault upthrowing west. There is, even in spite of the fault, a 

small outlier of Great Oolite and Cornbrash at Shillington, 4 miles still farther 

west, making the total length of the projection 9 miles. 

It can hardly be supposed that the anticline and syncline, so close and so 

perfectly parallel, did not take part in the same movements; it is necessary to 

consider them as one. It can therefore be definitely said that the last movements 

along the Melton Mowbray Axis were later than the highest Jurassic 

rocks in the district—the Oxford Clay; and from this it follows that they were 

probably intra-Cretaceous or Tertiary or both. If the anticline really dies out 

eastwards as Messrs. Cox and Trueman consider is suggested by the map, 

this does not prove the movements to have been intra-Jurassic, any more than 

would the dying out in both directions of any of the periclines strung along 

the other axes (e.g. Kingsclere and Bower Chalke) were the Cretaceous strata 

removed from the visibly folded areas. 

As Dr. Rastall has remarked, the Melton Mowbray Axis is difficult to correlate 

with any other system of folds, owing to its anomalous direction. Messrs. 

Cox and Trueman called its strike E.-W., but Dr. Rastall, apparently with 

reason, regards it as more nearly ENE.-WSW. It is, therefore, not parallel 

with the Market Weighton Axis. We have seen, however, how general the 

tendency is to curve and wander from any true line in the larger E.-W. axes 

farther south. It is probably legitimate to regard this as the most northerly of 

the great E.-W. folds, which suffered their maximum uplift in the Miocene 

and are most acute in the south, becoming fainter northward away from the 

source of pressure. Before the question can profitably be discussed further, 

detailed research on the stratigraphy of the Inferior Oolite is essential. If such 

research reveals an important phase of movement between the Bajocian and 

Vesulian, there will be strong grounds for correlation with the E.-W. group. 

Professors Cox and Trueman have already shown that there is evidence of 

movement between the Middle and Upper Lias, since the acutum zone 

appears to be absent over the anticline, while it is well developed on either 

side. 3 

1 A. H. Cox and A. E. Trueman, 1920, loc. cit., p. 198. 


3 Cox and Trueman, 1920, loc. cit., p. 201.

THE CHARNIAN AXES 79 

(?6) THE MARKET HARBOROUGH AXIS 

Professors Cox and Trueman and Dr. Rastall have discussed the appearances 

of an anticlinal axis running from near Market Harborough to Peterborough, 

and, although the evidence is as yet vague, it seems to be agreed that 

there is probably an axis along this line, parallel and contemporaneous with 

that at Melton Mowbray. As summarized by Dr. Rastall, 

'the map shows a long projection of rocks up to Cornbrash as far as Peterborough, 

and the general lie of the strata indicates distinctly an anticlinal axis running from 

Market Harborough to Peterborough, parallel to the Melton Mowbray axis. It is 

probably significant that, as pointed out by Cox and Trueman in the first case, the 

Pre-Cambrian outcrops of Charnwood Forest and Nuneaton lie on the westward 

prolongations of these axes . . .' 1 

The only piece of stratigraphical evidence suggesting intra-Jurassic movements 

seems to be Prof. Trueman's observation that the acutum zone is 

absent, or at least has never been recorded, near Market Harborough. 2 Southwestward 

the Rhaetic Beds show contemporaneous erosion near Rugby, but 

this is on the Nuneaton Axis also (see p. no). 

The Charnian Axes: 

(i) CHARNWOOD, (2) NUNEATON, (3) SEDGLEY-LICKEY, (4) WOOLHOPE-MAY 

HILL, (?5) UPWARE AND OTHER POSSIBLE AXES. 

In 1925 Dr. R. H. Rastall published an illuminating paper, in which he 

showed that the Charnian rocks in the Bletchley Boring were not, as had 

previously been supposed, part of a broad ridge continued southward from 

Charnwood Forest, but that they lay on a parallel axis striking NW.-SE. He 

also traced the courses of four axes of the same trend in the Southern Midlands, 

and concluded that 

'the general structure of the Midlands is due to the superposition of a fanlike 

virgation of the Pennine axis on a pre-existing series of folds with a NW.-SE. 

(charnoid) trend, the whole being limited on the west by the outer margin of the 

Caledonian fold-system, and on the south by the outer margin of the Armorican 

system, while on the east the relations are unknown.' 3 

He likened the process to the bending of a sheet of corrugated iron by pressure 

applied obliquely to the corrugations. A third system of folds was imposed, 

as we have just seen, by pressure acting S.-N. This gave rise to the important 

axes of Armorican trend. 

Dr. Rastall pointed out that the anticline in Charmvood Forest, as Prof. 

Watts had shown, strikes almost exactly NW.-SE., and moreover that 

Charnian rocks have been proved exactly on the continuation of this line in 

borings at Leicester and Orton (5 miles west of Kettering). Therefore it would 

only be by serious distortion that the line could be made to pass under 


2 Cox and Trueman, 1920, loc. cit., p. 201. These authors also point out that the especially 

deep retreats of the Lias and Oolite escarpments at Weedon and Banbury suggest axes, but no 

evidence for anticlines at these places seems to have been obtained. 

3 R. H. Rastall, 1925, 'The Tectonics of the Southern Midlands', Geol. Mag., vol. lxii, 

p. 213.


Bletchley. On the other hand, about 17 miles south-west of the Charnwood 

Forest Axis, there is the parallel ridge of Pre-Cambrian and Cambrian rocks of 

Nuneaton and Atherstone, with the Caldecote Series of Pre-Cambrian 

volcanics. This line points straight for the Bletchley Boring, and the meagre 

specimens of volcanic rocks from the boring agree just as well with the 

Atherstone Series as with those in Charnwood Forest. 1 

Dr. Rastall showed also that over both of these axes the Lower Greensand 

is affected. On the continuation of the Charnwood Axis, south-west of Sandy, 

it becomes very thin, while 20 miles farther south-west, on the continuation 

of the Nuneaton Axis, it disappears altogether near Leighton Buzzard. 

The Sedgley-Lickey Axis lies about the same distance to the south-west, 

where, as Lapworth showed, three of the Pre-Cambrian and Silurian inliers 

of the South Staffordshire coal-field (Sedgley, the Wren's Nest and Dudley) 

form a NNW.-SSE. line, pointing approximately towards the Lickey Hills. 

Still farther to the south-west, and about the same distance beyond the 

Sedgley-Lickey Axis, a fourth line is suggested by the two dome-like inliers 

of Silurian rocks which rise through the Old Red Sandstone at Woolhope and 

May Hill. These are areas of superelevation due to the intersection of two 

anticlinal axes. The line joining them has again an approximately NW.-SE. 

strike and seems to belong to the Charnian fold system. It certainly forms 

with the others a remarkably regular series of axes of similar constitution, 

evenly spaced, and with approximately parallel strike. It might be expected 

that any movement would be felt along all of them simultaneously. 

Detailed investigation of the Corallian Beds of the counties of Wilts., Berks, 

and Oxon. has revealed unmistakable signs of relative uplift in Corallian times 

in two areas, about Oxford and about Purton and Wootton Bassett. As I 

showed in 1927, in these two areas, each extending along 8 or 9 miles of the 

outcrop, the sea-bed was unstable and sedimentation was abnormally retarded 

throughout Corallian times. 2 Each of the subdivisions becomes thinner, 

overlaps the subdivisions below, or disappears altogether over the critical 

regions. These regions I therefore regarded as axes of uplift, and named them 

the Oxford and Purton (perhaps better Wootton Bassett) Axes. (For a more 

detailed account of the stratigraphical anomalies connected with them, see 

Chapter XIII, pp. 393, 403, et seq.) 

I pointed out at the same time that the Oxford and Wootton Bassett Axes 

lie approximately along the continuations of the older Sedgley-Lickey and 

May Hill lines, and suggested that they were due to posthumous uplift along 

those lines. When the gentle curve of the line joining the centres of the 

Woolhope and May Hill domes is continued south-eastwards it passes up the 

Nailsworth Valley, under Charlton and Garsdon, near Malmesbury, towards 

Wootton Bassett or Tockenham—that is towards the centre of the Wootton 

Bassett Axis. The distance from May Hill is 32 miles. 

The connexion with the Oxford Axis and the Sedgley-Lickey line is less 

convincing and the distance is greater—50 miles. The axis of the ancient 

anticline is here less clearly marked and it is correspondingly difficult to foretell 

where it would lie underground at so great a distance. If we join up the 

1 R. H. Rastall, 1925, loc. cit., pp. 199-202, where all references are given and the subject 

is treated in much greater detail. 

2 W. J. Arkell, 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, pp. 120-2.


three inliers of Sedgley, Wren's Nest and Dudley and project the line perfectly 

straight, it passes under Oxford City, which is on the centre of the 

Oxford Axis. This line does not lie along the Vale of Moreton, but passes 

rather east of Chipping Norton. On the other hand it also fails to pass through 

the Lickey Hills; to include them a slight detour of 2 miles to the SW. is 

necessary. The line may curve back again from the Lickey Hills and run 

towards Oxford, but if it continued to diverge at the same rate it might pass 

not merely through the Vale of Moreton but still farther west. However, as 

already shown, the phenomena in the Vale of Moreton are adequately explained 

by the Pennine Axis. 

The other two axes, those of Charnwood and Nuneaton, lay beneath the 

Ampthill Clay area in Corallian times, where conditions of sedimentation 

were very different. Exposures in the clay district are so rare that we know 

nothing of the detailed stratigraphy from place to place along this part of the 

outcrop, and any changes there may be in the equivalent of the Corallian 

either near Leighton Buzzard or south-east of Bedford have still to be discovered. 

But some 25 miles north-east of the Charnwood Axis (that is, about 

as far beyond it as the average distance between the four known axes) lies the 

shallow-water reef and oolite shoal of Upware, completely surrounded by clay 

deposits. This isolated reef might possibly owe its existence to uplift of the 

sea-bed along a fifth axis of the Charnian group, but this is a matter of conjecture 

only. 

Uplifts subsequent to those in the Corallian period have only been satisfactorily 

proved over the Charnwood and Nuneaton Axes, where, as Dr. 

Rastall showed, the Lower Greensand is affected. It may also be significant 

that the Nuneaton and Sedgley-Lickey Axes accurately delimit the 

area in which the Portland and Purbeck Beds occur in Oxon. and Bucks. 

—namely between Stewkley, near Leighton Buzzard, and Nuneham, near 

Oxford. 

Earlier movements seem to be traceable with certainty only in the Rhaetic 

Beds and Middle Lias. On the Charnwood Axis the Rhaetic Beds at Leicester 

contain small pebbles of igneous rocks from Charnwood Forest, but this does 

not indicate special uplift. A short distance south of Leicester, however, the 

Langport Beds finally die out, not to reappear again (so far as is known) 

farther north (see p. no). The Marlstone of the Middle Lias undergoes 

marked attenuation over the region of the axis, and between Hallaton and 

Keythorpe it disappears altogether (see p. 157). 1 

The Nuneaton Axis passes a mile or two south-west of Rugby, close to the 

village of Church Lawford, where Richardson has described 'abundant evidence 

for a non-sequence between the White Lias (Langport Beds) and the 

superincumbent Lower Lias'. There is a ferruginous deposit and the usual 

signs of erosion, while parts of the White Lias are pebbly, and tht planorbis 

zone rests non-sequentially on its bored and pitted upper surface. 2 

The Sedgley-Lickey Axis too, wherever we draw its ultimate continuation, 

passes first of all through an area of disturbed and attenuated Rhaetic Beds in 

1 Between Barrowden and Wakerley, east of Uppingham, the Northampton Sands disappear 

and Lincolnshire Limestone comes to rest on Upper Lias; but this is 10 miles from the 

nearest point on the line of the Charnwood Axis (see p. 213). 

2 L. Richardson, 1912, Geol. Mag. [5], vol. ix, p. 32.


the tongue of outcrop west of Stratford on Avon, about Binton, Grafton and 

Bickmarsh. This is the area where the Rhsetics are capped by the 'Guinea 

Bed', a conglomeratic basement-bed of the Lower Lias, containing derived 

Rhaetic fossils (see p. 135). This area lies directly across the North Cotswold 

Syncline, not many miles north of Mickleton, where the Lower Lias reaches 

its record thickness of about 1,000 ft. It seems, therefore, to prove conclusively 

that the syncline was crossed by a line of uplift on the continuation of 

the Sedgley-Lickey Axis. The whole of the area of disturbance is too far west 

to be due directly to the Vale of Moreton Axis, though it is about on the line 

of the Vale of Moreton Axis that the White Lias begins to make its reappearance, 

after being absent over most of Gloucestershire and Worcestershire. 

It is possible that this Sedgley-Lickey Axis may have been influential in limiting 

the Banbury iron-field (Marlstone ironstone) on the south-west, but there 

seems little definite evidence. 

On the Woolhope-May Hill Axis the Rhaetic Beds tell quite another story. 

Only 4 miles from the Silurian rocks of May Hill, and directly on the line of 

the anticlinal axis (i.e. SE. of May Hill) the Rhaetics of Chaxhill, near Westbury 

on Severn, show 'very striking evidence of a syncline' 1 as noticed above. 

In fact the Woolhope-May Hill Anticline in the Lower Palaeozoic rocks 

seems to point nearly into the centre of the Painswick Syncline in the Inferior 

Oolite 10 miles away. Clearly here, as we pass farther south, the movements 

of Armorican trend were paramount and totally obscured those of any other 

directrix. 

Evidence of movements along the Charnian axes during the time of the 

Lower Oolites is wholly inconclusive. The phenomena in the Evenlode 

Valley, which Dr. Rastall suggested might be due to the crossing of the Pennine 

Axis by the Sedgley-Lickey Axis near Kingham, in the Vale of Moreton, 2 

are, as we have seen, capable of another more probable explanation. In Inferior 

Oolite times the Armorican and Malvernian axes seem to have controlled 

sedimentation without interference by movements of other trends, for 

the Malvern Axis seems to have determined the western boundary and the 

Pennine the eastern boundary of the Cotswold Syncline, while the Birdlip 

Anticline subdivided it transversely. Between the other Charnian axes and 

the phenomena displayed by the Inferior Oolite it seems impossible to 

establish any connexion. On the contrary there was steady overlap towards 

the east and south-east. The Clypeus Grit passes across the continuation of the 

Sedgley-Lickey Axis and comes to an end beyond it, between the valleys of 

the Evenlode and Cherwell; the Hook Norton Beds die out midway between 

this axis and the next, while the White Sands of the fusca zone seem to die out 

between the Nuneaton and Charnwood Axes (see pp. 207, 304). 

In the principal periods of posthumous activity, therefore, there is a fundamental 

difference between the Charnian Axes and those of Armorican and 

Malvernian trends; for while two or three or possibly all of the Charnian Axes 

experienced activity in Corallian times but were quiescent in the Bajocian, 

the others displayed intense activity during the Bajocian Denudation but 

lapsed into tranquillity during the Upper Jurassic. 

During the Great Oolite period differential movements of the sea-bed 

certainly occurred, but they have not yet been satisfactorily traced to any 

1 L.Richardson, 1904, loc. cit., p. 356. 

2 R. H. Rastall, 1925, loc. cit., p. 215.


particular system of axes. Such regions of uplift as are known in the Upper 

Estuarine Series of Northamptonshire 1 and in the Forest Marble of Oxfordshire 

2 seem to have no connexion whatever with the known axes, either in 

regard to distribution or direction. It appears that the same may also be said 

of the local uplifts controlling the distribution of the Stonesfield Slate. 

Stratigraphical anomalies are frequent along the outcrop of the Cornbrash, 

and a close study of this formation seemed at first more promising than almost 

any other for tracing possible connexions between sedimentation and ancient 

axes of upheaval. Only two of the anomalies, however, coincide with known 

axes, leaving many others unexplained. Those two are a boulder-bed in the 

Upper Cornbrash at Charlton and Garsdon, near Malmesbury (on the Woolhope-May 

Hill line), and extreme attenuation of both Upper and Lower 

Cornbrash in the Ouse Valley, from Bedford north-westward (approximately 

along the line of the Charnwood Axis). These two phenomena belong to 

different categories, however, for while the Lower Cornbrash is very thin 

in the Ouse Valley, it is exceptionally thick around Malmesbury; and the 

boulder-bed near Malmesbury forms part of the siddingtonensis zone, which 

is probably missing altogether in the Ouse Valley. All things considered, the 

evidence of movement along particular axes during the deposition of the 

Cornbrash is unsatisfactory. 3 

Before leaving the axes of Charnian trend, mention must be made of some 

suggestions put forward by Prof. Hawkins in 1918, before the appearance of 

Dr. Rastall's now well-known paper. From a consideration of the ideal resultants 

between dip and pitch along the southern margin of the London 

Basin as compared with the actual resultants shown by the strike of the rocks, 

he came to the conclusion that the western end of the basin was crossed by 

two very shallow cross-folds striking NNW.-SSE. 4 One of these anticlines 

was supposed to pass through White Horse Hill and the Shalbourne Pericline, 

the other from about Lockinge, near Wantage, through the Kingsclere 

Pericline, close to Kingsclere. By this means it was sought to explain the 

similarity in outline between the escarpments of the Berkshire Downs on the 

north and the Hampshire Downs on the south, as well as the origin of the two 

periclines. The further discussion of this problem does not concern us here, 

since no traces of any intra-Jurassic or even intra-Cretaceous movements have 

been recorded along the continuations of either of these lines. One point is of 

special interest, however: Prof. Hawkins speaks of the Goring Gap, through 

which the Thames flows at Goring, as a 'broad shallow syncing 5 of Charnian 

trend. This is not at all consistent with Cox and Trueman's or Rastall's 

suggestions that the Goring Gap may have been determined by an anticline 

of this trend (for Cox and Trueman the anticline runs down the Cherwell 

Valley from Banbury; for Rastall it comes from the Lickey Hills via the Vale 

of Moreton). Prof. Hawkins has local knowledge, and if the Thames runs 

1 B. Thompson, 1930, Q.J.G.S., vol. lxxxvi, pp. 447-9 and PI. li. In spite of what Mr. 

Thompson says (p. 447) it may be surmised that his largest 'anticline' along the Nene Valley 

from Rushden to Wad^nhoe is merely the marginal thinning of the Great Oolite Series southeastwards, 

as Judd thought (see below, p. 310). 

2 W. J. Arkell, 1931, Q.J.G.S., vol. lxxxvii, pp. 563-95. 

3 J. A. Douglas and W. J. Arkell, 1928-32, Q.J.G.S., vote, lxxxiv and lxxxviii; also below, 

Chapter XI. 

4 H. L. Hawkins, 1918, Proc. Hants F. C., vol. viii, part ii, pp. 16-21. 

5 Loc. cit., p. 20. 

M4S71 

G

84 C O N T E M P O R A N E O U S T E C T O N I C S 

through a syncline at Goring, the line of uplift which caused the retreat of the 

escarpment between Wallingford and Blewbury must strike across it instead of 

along the gap from NW. to SE. as the other authors have supposed. This 

offers substantial support for the view of the underground course of the 

Birdlip Axis outlined above. 

One more supposed anticline of Charnian trend must be mentioned, though 

it probably has no connexion whatever with the others. It affects the Chalk 

and underlying Jurassic near the sharp angle in the Dorset Downs, where, 

according to Osborne White, an ill-defined, depressed fold runs from Ibberton 

north-westward, towards Milborne Port. 1 It seems probable that the appearance 

of an anticline here is due to the margin of the Hants-Dorset E.-W. 

syncline intersecting the rocks dipping east, with a N.-S. strike, along the 

continuation of the Malvern Axis. The change of dip is too large and general 

a feature to be caused by the anticline, and it is more likely that the anticline 

is the effect rather than the cause. 

Some Axes of Similar Trend but of a Different Type. 

(1) THE CLEVELAND AXIS 

So great an authority as Prof. Kendall believes that the Peak Fault resulted 

from the fracture of a monocline, and as there seems no doubt that the first 

fracture took place actually during the deposition of the Upper Lias, there is 

some reason for supposing that uplift may have started along the anticline 

which now forms the axis of the Cleveland Hills as early as Liassic times. 

The evidence will be discussed in more detail in Chapter VII, pp. 180-1. 

In general Cleveland, lying in the centre of the Yorkshire Basin, was certainly 

a region of subsidence and heavy sedimentation all through the Jurassic 

period. Any uplift at the Peak can only have been a local and relatively 

insignificant occurrence within the synclinorium. 

(2) THE LOUTH—WILLOUGHBY AXIS 

In 1905 Prof. Kendall drew attention to what he termed the Louth- 

Willoughby Axis, defining it as 'a long anticlinal fold [in the Cretaceous rocks] 

running through Lincolnshire from the Wash in a north-westerly direction 

as far as Louth'. 2 He remarked that the Jurassic rocks appear to be especially 

thick along this line, and he therefore considered it a post-Cretaceous anticline 

superimposed on a Jurassic syncline, analogous with the Yorkshire 

Basin (Cleveland). Its path is conspicuous on the map by reason of the long 

tongue of Lower Cretaceous rocks running from the Wash up into the 

Chalk area. 

If this line be swung round a few degrees to slightly west of north-west 

beyond Louth, it coincides with the line of uplift which Dr. Versey calls the 

Caistor Axis. 3 This passes off the Chalk outcrop a short distance north of 

Caistor, and Dr. Versey believes that its continuation is indicated by the deflections 

in the Lias and Lower Oolite scarps at Flixborough and Santon. It 

seems to be approximately parallel with the Market Weighton Axis, and 

1 H. J. Osborne White, 1923, 'Geol. Shaftesbury', Mem. Geol. Surv., p. 5. 

2 P. F. Kendall, 1905, loc. cit., p. 201. 

3 H. C. Versey, 1931, Proc. Yorks. Geol. Soc., vol. xxii, pp. 55-6.

SKETCH MAP 

OF TH E CENTRAL PORTION OF 

SOUTHERN ENGLAND 

TO SHOW THE TECTONIC TREND-LINES 

THICK LINES REPRESENT THE PRINCIPAL ANTICLINAL 

AXES WHER.E ACTUAL EVIDENCE FOR UPLIFT EXISTS; 

PRESUMED CONTINUATIONS OF ANTICLINES IN BROKEN 

LINES. COMPILEO FROM VARIOUS SOURCESAS 

INDICATED INTHE TEXT. 

FIG. 15.

THE LOUTH-WILLOUGHBY AXIS 85 

Dr. Versey places the centre of the intervening syncline at Elsham, three 

miles north-north-east of Brigg (fig. 10, p. 60). 

In Jurassic times this axis can have been in no way analogous with that at 

Market Weighton, but during the time of the Lower Cretaceous and immediately 

pre-Cretaceous movements it presented some analogies. Near Caistor 

the 'Carstone', believed to be locally of Lower and Middle Albian date, rests 

on Kimeridge Clay—a very considerable hiatus. About Willoughby, however, 

comparatively thick marine Neocomian strata are developed. It is evident, 

therefore, that uplift was less intense towards the south-east—that the axis 

died out in that direction. It is possible that if erosion or deep borings were 

to give any insight into what becomes of the Market Weighton Axis towards 

the south-east, it also would be found to fade away in the same direction. 

The Willoughby-Caistor Axis is difficult to classify. In direction it is intermediate 

between the Market Weighton and the Charnian Axes; the strike at 

Caistor is more nearly parallel with the Market Weighton line, 1 but between 

Louth and Willoughby it is truly Charnian (due NW.-SE.). It agrees with 

both Charnian and Market Weighton Axes in giving rise to an overlap of the 

Lower Cretaceous by the Albian, but it is fundamentally different from both 

in having been a syncline through most of Jurassic times. Dr. Rastall describes 

it as 'an old Charnoid axis, probably synclinal in the Jurassic and 

anticlinal later, to which subsequent movements readily adapted themselves'. 2 

Definite evidence that the axis was synclinal at least in the Great Oolite 

period is provided by the Brigg boring (see p. 311). 

More will be said of this type of axis in Chapter XVIII. 

Axes of Caledonian Trend. 

(i) THE ISLIP AXIS 

North-east of Oxford an anticlinal axis running NE.-SW. is marked by 

a line of six Cornbrash inliers rising through the Oxford Clay lowlands near 

Ot Moor, at Islip, Oddington, Merton, Ambrosden, Blackthorn Hill and 

Marsh Gibbon. The largest of the inliers bring up Great Oolite in the centre. 

The axis seems to consist of a chain of small domes, but it can be traced for 

considerable distances in both directions. Towards the south-west its effects 

can be clearly seen in the Corallian rocks of Wytham Hill 3 (a distance of 

16 miles from the farthest inlier at Marsh Gibbon), and the Corallian rocks 

are again arched up on the same line 12 miles farther on, at Shellingford. 4 

Towards the north-east the last certain traces are seen in the brick pit at 

Calvert, where trouble has been caused by the shaly brick clays or 'knots' of 

the Lower Oxford Clay suddenly dipping underground and being replaced 

by soapy clays of higher zones, as the expansion of the works has caused 

the pit to extend across the southern limb of the fold. It can therefore be 

definitely said that the Islip Axis is at least 30 miles long and that its date is 

mainly post-Corallian. 

The direction of strike is quite peculiar and cannot be reconciled with any 

1 Dr. Versey calls the strike of the Market Weighton Axis NW.-SE., but Dr. Rastall 

considers it only W. 5 0 N. (1927, Geol. Mag., vol. Ixiv, p. 24): apparently WNW.-ESE. 

would be a nearer approximation to the truth. 


3 T. I. Pocock, 1908, 'Geol. Oxford', Mem. Geol. Surv., p. 20. 

4 W. J. Arkell, 1927, loc. cit., p. 103.


other known folds of comparable importance, but its agreement with the 

general strike of the rocks is noteworthy and may be significant. If the two 

are causally connected, a Tertiary age is suggested for the Islip Axis, but this 

does not exclude the possibility of earlier beginnings. 

A few observations on the possible extension of this axis may not be entirely 

idle, since an axis that can be traced for 30 miles may well be much longer. 

In the first place, if the line be continued a further 29 miles south-west of 

Shellingford it is found to reach exactly to the spot where the Lower Greensand 

unaccountably oversteps the Kimeridge Clay and Corallian between 

Rowde and Bromham, near Devizes, coming to rest for about if miles on 

Oxford Clay. A few miles beyond this and almost on the same line are the 

Hilperton-Trowbridge inlier of Cornbrash and the Hardington inlier of 

Inferior Oolite. These two inliers indicate an anticline almost parallel with 

the Mendip-Vale of Pewsey Axis, but appearing to diverge from it at a low 

angle somewhere in the Mendip Hills. The chief objection to the idea that this 

anticline is really a continuation of that at Islip is the too-accurate straightness 

of the line—for, as we have seen, it is not in the nature of the other axes to 

pursue a straight course for very long. Nevertheless, the 30 miles that are 

definitely visible are almost mathematically straight, just as some of the 

Charnian Axes appear to be, and there is therefore no reason why it should 

not be the same for 75 miles. 

If the axis be continued in the opposite direction some more remarkable 

coincidences appear. Three miles north-east of Calvert (where the fold is 

still intense) the general course of the River Ouse begins to coincide with 

the line and continues straight (notwithstanding minor meanders) for 25 miles. 

The last 8 miles of this reach, from Olney to Sharnbrook, are highly suggestive 

of some fundamental structural cause, a view that is confirmed by two 

Cornbrash inliers at Riseley, a few miles farther on, which continue the line 

after the river valley has bent south-eastwards at right angles. (This southeast 

part of the river, from Sharnbrook to Bedford, which is set so conspicuously 

at right-angles to the higher course, lies, as already mentioned, 

approximately along the Charnwood Axis.) The Riseley inliers are not quite 

mathematically in line with the Oxfordshire ones, the axis having apparently 

bent a few degrees northwards. If they are on one and the seme line, they 

extend the Islip Axis by 33 miles—about as far as the Hilperton-Trowbridge 

inlier—making the total length possibly 100 miles. If this is all one fold it is 

evidently a highly important one. Hitherto, however, no sign", of intra- 

Jurassic movements have been discovered along it. 

(2) SOME MINOR YORKSHIRE AXES 

Blake and Hudleston and Fox-Strangways remarked on 'a slight upthrow 5 

or 'a slight roll' in the Lower Corallian strata at Appleton-le-Street in the 

Howardian Hills, which alters the strike for a short distance. 1 More recently 

Dr. Versey has re-examined the ground and has come to the conclusion that 

the anticline has a Caledonian (NE.-SW.) trend. 2 He has also detected three 

other small anticlines of similar strike in the vicinity, spaced fairly regularly 

at intervals of just under 7 miles, at Roulston Scar, Gilling Park, and on the 

1 Blake and Hudleston, 1877, Q.J.G.S., vol. xxxiii, p. 362. 

2 H. C. Versey, 1929, Proc. Yorks. Geol. Soc., vol. xxi, pp. 206-10, and fig. 8, p. 207.

THE ISLIP AXIS 87 

other side of Appleton-le-Street, at Grimston Field House. There seems to 

have been poverty of sedimentation due to uplift at these localities during the 

formation of the Lower Calcareous Grit and perhaps also the Oxford Clay, 

but Dr. Vernon Wilson informs me that his researches show that any such 

movements had ceased before the deposition of the 'Upper Corallian' limestones. 

It is hoped that further minute stratigraphical work on the Jurassic 

rocks will throw more light on these and other small intra-Jurassic axes in 

Yorkshire. 

TABLE VI. The principal axes and their periods of activity. 

+ denotes proved uplift (relative to the surroundings). 

— denoted proved subsidence (relative quiescence or downsinking). 

? denotes that evidence is needed. 

CLASSIFICA- 

TION AC- 

CORDING TO 

DIRECTRIX. 

NAMES OF 

AXES. 

Periods. 

Pur beck-Wey mouth. 

North Devon-W ardour. 

ARMORICAN GROUP. 

£ 

8 


In the second place it emerges that, although the movements were often 

protracted and gentle, they were not of the broad, regional type which Gilbert 

named epeirogenic; for they were restricted to certain tectonic lines, and these 

coincided with the buried axes of more ancient upheavals of the convulsive 

and episodic type, recognizable at once as orogenic. Moreover, at least all 

the axes of E.-W. (Armorican) direction were subsequently rekindled into 

orogenic activity during the Alpine folding of the Miocene period. 

Thus these axes are really orogenic lines, and although through most of 

Mesozoic times they were probably almost stable, only appearing to rise in 

relation to the subsiding sea-bed around them, it would seem that they depend 

merely on a greater degree of pressure to make them rise in relation to sealevel 

and to take part in mountain-building movements which all would class 

as truly orogenic. Whether we regard the movements as the dying tremors 

of past orogenies or as the faint anticipations of others yet to come, they differ 

from more obvious orogenic processes only in date and degree, and it would 

be highly artificial to draw a sharp line of distinction between them by calling 

the Jurassic movements epeirogenic. We have only to go farther afield, into 

North-West Germany, to find that the time-distinction breaks down also, 

for there contemporaneous folding attained mountain-building proportions. 

Faced with the mountain-chains of the Teutoburger Wald, the Egge Kette, 

the Siintel and the Deister (to go no more than 60 miles from Hanover), all 

raised partly in Mesozoic times, we are hard pressed to find means of 

differentiating between the forces that gave rise to them and the much 

greater ones that built the Alps. 

It is not surprising that the classification of these movements has evoked 

conflicting opinions. The differences depend ultimately upon the definitions 

of the terms orogenic and epeirogenic, a matter concerning which there is as 

little agreement as over the correct meaning of the expression geosyncline. 

The leading authority on the subject is generally recognized to be Prof. 

Hans Stille of Gottingen, who has been investigating and publishing papers 

upon the Mesozoic movements in North-West Germany for the past thirty 

years. In 1924 he collected together the results in his great work Grundfragen 

der vergleichenden Tektonik, and from this must start any attempt to understand 

or correlate the English tectonic events. 

As conceived by Stille: 1 

Orogenic processes define themselves 

1. as changes in the structure of the underlying platform, 

2. as episodic. 

Epeirogenic processes, on the other hand, 

1. leave the tectonic structure of the platform intact, 

2. continue through long periods of geological time (are 'secular' processes), 

3. are widespread. 

'And so the conception of orogeny partakes of the spirit of the convenient expression 

"mountain-building" . . . 

. . . 'And when we treat the conception orogeny in the same way [as mountainbuilding 

used in its modern sense], we are hardly departing from Gilbert's original 

idea, for that was based on the contrast between widespread warping, the example 

of which is Lake Bonneville, and "real" tectonic events, such as have produced, for 

example, the separate mountain ridges of the type of the Basin Ranges. 

1 H. Stille, 1924, Grundfragen, p. 11.

EPEIROGENIC AND OROGENIC PROCESSES 89 

'Epeirogenic events are the form assumed by tectonics in "anorogenic" times. 

They comprise protracted and more or less uniform movements, affecting wide 

tracts of the earth's crust—large-scale movements of bigger units than are involved 

in an orogeny.' 

Again 'Orogeny produces anticlines and synclines (ridges and furrows); epeirogeny 

produces geanticlines and geosynclines (broad elevations, basins and troughs).' 1 

If we accept these definitions (and they are in harmony with the views of 

most modern writers) then the downsinking of the Jurassic troughs of sedimentation 

or 'aires d'ennoyage , is to be classed as epeirogenic, as well as the 

general uplift that is presumed to have affected the whole technically stable 

block by which the epeiric seas were supported (as explained on p. 59, in 

connexion with cyclic sedimentation). As orogenic events, on the other hand, 

appear the differential movements along the axes of uplift. 

Earlier writers formulated different definitions. Haug, 2 for instance, basing 

himself on the work of James Hall, distinguished the kinds of tectonic 

activities largely according to the nature of the milieu in which they took place. 

According to the Haug school orogenic movements are confined to geosynclinal 

regions, epeirogenic to the continental areas or geanticlines. Thus 

Prof. Dacque, 3 rejecting Stille's conception of the downsinking trough of 

North Germany as a small geosyncline, cannot accept the folding of the 

Teutoburger Wald and associated ranges within the trough as analogous with 

the Alpine movements on a small scale, because the Alpine folds arose out of 

a true geosyncline (the Tethys). He claims that the lesser folds of North- 

West Germany, which for him are of epeirogenic origin, are due to lateral 

pressure, w T hile the great Alpine movements that arose out of the geosyncline 

of Tethys did not result from external pressure but from internal forces of 

a different kind, and therefore they alone should be called orogenic. Such 

a classification based on causes might be ideal were there any certainty of its 

correctness. But at present the whole question of causes is far too hypothetical 

for us to be able to take any cognizance of them, and we must classify phenomena^?* 

se. If this be agreed, then Stille's system has no equal. 

It is to Stille that we owe our only rational ideas of the tectonics of the 

Mesozoic period. His pioneer researches in North-West Germany produced 

ordered knowledge where ignorance reigned before. 

Finding all existing names ambiguous, owing to their having been used in 

a directional sense, he coined the new term Saxonian Folding for all the 

mountain-building movements, of any directrix whatever, that occurred in 

the extra-Alpine region of North-West Europe after the Variscan (or Hercynian, 

or Altaid, that is, Carbo-Permian) orogeny. 4 Analysing these movements, 

he found that they occurred in a number of phases spanning Mesozoic 

and Cainozoic time, and all those falling between the Trias and the Cretaceous 

he called Cimmerian (Kimmerisch), a term borrowed from the Crimean 

Peninsula (Krim). The Cimmerian Mountains were described by Suess 5 as 

'The remains of a folded chain of Mesozoic [pre-Neocomian] age, which 

forms the Crimea and Dobrudscha (Dobrogea), embraces the mouths of the 

1 H. Stille, 1924, loc. cit., p. 15. 

2 E. Haug, 1907, Traitede Geologic, p. 160; also Kober, 1928, Bau der Erdey 2nd ed., p. 84. 

3 E. Dacque, 1915, Grundlagen und Methoden der Palaogeographie, pp. 131—3. 

4 H. Stille, 1913, Geol. Rundschau, vol. iv, pp. 364, 366; and 1924, loc. cit., p. 131. 

5 E. Suess, The Face of the Earth, English ed., vol. iv, 1909, pp. 23 and 632.

go CONTEMPORANEOUS TECTONICS 

Danube, and disappears beneath the projecting arc of the Carpathians'. He 

recognized two periods of folding: the first between the Trias and the Lias, 

which Stille calls Older Cimmerian, the second between the Jurassic and the 

Neocomian, which Stille calls Younger Cimmerian. These are nearly everywhere 

the two principal phases of the Cimmerian movements, but when the 

Jurassic system is traced into other parts of Europe a number of sub-phases 

are revealed. Three are recognizable in the North German Basin, where they 

have been given names by Dahlgriin: 1 the earliest, the Deister Phase, falls 

within the Lower Kimeridgian (before the Gravesia zones); the next, or 

Osterwald Phase, falls within the Purbeckian (before the Serpulite, or Middle 

Purbeckian); the last, or Hils Phase, within the Neocomian (between the 

freshwater Wealden and the marine Upper Valanginian or Hils Clay). 

The criteria by which these tectonic phases may be recognized are the 

disturbance (folding and erosion) of the underlying strata and the overstepping 

of the superjacent stratum transgressively across their basset edges. 

In England perhaps the most familiar discordance of this sort is the transgression 

of the Vesulian (garantiana and truellei zones) across all the underlying 

rocks down to the Carboniferous Limestone of the Mendips. If we 

regard such interruptions in the stratification purely from the point of view 

of tectonics and give them all special tectonic names as Dahlgriin has begun 

to do, we are faced with a completely new nomenclature, a chronology of 

tectonics bearing no relation to ordinary geological chronologies and requiring 

to be memorized independently. The giving of such names as Deister Phase 

would proceed almost indefinitely as knowledge became extended over new 

territories, and the prospect of the history of stratigraphical and chronological 

nomenclature repeating itself is highly disconcerting. Such a course seems 

wholly unnecessary. We already have two time-scales, and well may we ask 

what is the use of them if they cannot be brought into play for the purpose 

of dating tectonic as well as any other events. 

Several methods of expressing the same ideas have already long been used 

by English geologists, always with the aid of the existing chronologies. 

Buckman spoke of the interruption between the Bajocian and the Vesulian as 

the Bajocian Denudation, and of the similar but somewhat lesser one between 

the Bajocian and the Aalenian as the Aalenian Denudation. Prof. Sollas refers 

to the same phenomena as the Bajocian Oscillation and the Aalenian Oscillation, 

2 a change which is an improvement in so far as it directs attention to the 

cause rather than to the effect. But a still greater improvement would be to 

speak of the Vesulian Oscillation instead of the Bajocian, and the Bajocian 

Oscillation instead of the Aalenian, thereby emphasizing the transgression 

(which was caused by a widespread, epeirogenic, oscillation) instead of the 

previous uplift (which was local, orogenic). Prof. Sollas has, in fact, adopted 

this plan in speaking of other oscillations, not previously named by Buckman. 

Thus he speaks of the Forestian Oscillation, which is denoted by an eroded 

surface below {at the base of) the Forest Marble (Kemble Beds), of a Ceteosaurus 

Oscillation, which is at the base of the beds containing Ceteosaurus (the 

Fimbriata-waltoni Beds), and so on. The preceding disturbances would then 

be the Pre-Vesulian, &c. 

1 F. Dahlgriin, 1920,Jahrb. Preuss. Geol. Landesanst., vol. xlii, p. 747. 

2 W. J. Sollas, 1926, Nat. Hist. Oxford Dist., p. 36.

T R A N S G R E S S I O N S A N D REGRESSIONS 91 

Such a system of naming oscillations (or whatever we choose to call them) 

after the transgressive stratum above the discordance has marked practical 

advantages. For instance, when we stand in Vallis Vale and look at the 

Vesulian (Upper Inferior Oolite) resting upon a smoothly-planed surface of 

the Carboniferous Limestone (as in plate XI, p. 238), the obvious way to 

describe what we see is to call it the Vesulian Discordance, resulting from the 

Vesulian Transgression. If we move to the escarpment in the South Cotswolds 

or Mid-Somerset we still find the discordance below the Vesulian, but there 

the transgressive bed rests upon various members of the Lias. Without 

previous knowledge we cannot describe this as the Bajocian Oscillation, for 

the Bajocian does not visibly enter into the matter. The only constant factor, 

the only criterion for dating, is always the Vesulian. 1 We do, in fact, know 

that where the sequence is as nearly complete as possible the Vesulian is 

immediately preceded by the Bajocian; that in England the Bajocian is involved 

in the pre-Vesulian folding; therefore that the 'denudation' or 'oscillation' 

is post-Bajocian. But in unexplored territory, where we had no knowledge 

of the ideal sequence, if we found a Jurassic stratum which could be 

dated to Vesulian resting discordantly upon Palaeozoic rocks, all that we could 

say would be that there had been a Vesulian transgression. The denudation 

or the oscillation might have taken place at any of the earlier periods unrepresented 

by sediments. 

It is important to keep distinct in our minds the two entirely different 

processes involved in such a discordance as that in Vallis Vale. First there is 

the folding and uplift of the rocks now covered by the transgressive stratum— 

a purely orogenic process. Secondly there is the general downsinking which 

allowed the folded and peneplaned strata to be submerged uniformly with 

the unfolded strata elsewhere—an epeirogenic movement not restricted to the 

region of the axes. 

We cannot always lightly use the word Transgression to signify nothing 

more than the transgressive overstep of one stratum by another, for the word 

has a special geological meaning. It signifies an extension of the sea over the 

land, a widening of the area of marine sedimentation, produced by epeirogenic 

movements; and of such an extension the mere occurrence of Vesulian 

rocks resting upon Palaeozoics on the axes of uplift is no evidence. Both in 

the Mendips and in Normandy there are often thin remanie beds between the 

Vesulian and the Palaeozoics, crowded with Liassic and Bajocian fossils, or 

Rhaetic and other remains may have fallen down cracks in the Palaeozoic 

rocks (see p. 105), proving that the missing sediments once existed there but 

were removed as the result of the folding. The resumption of sedimentation 

in Vesulian times over the folded axes, therefore, does not necessarily imply 

any great extension of the sea; it does not of itself indicate a true transgression, 

although it did, in fact, coincide with one. 

On the other hand a true transgression may occur without leaving any 

signs of discordance in the areas where the sea already existed and where no 

orogenic folding supervened. For instance the great Callovian Transgression, 

by which the sea for the first time in the Jurassic period overspread a great 

1 The lowest part of the transgressive stratum is usually slightly diachronic: for example, 

against the Mendips the garantiana zone is gradually overlapped by the truellei zone as the 

Carboniferous platform rises; but any diachronism through overlap is generally negligible in 

comparison with the differences in age of the underlying strata that are overstepped.


part of Russia, leaving Callovian sediments resting discordantly on Palaeozoics 

over hundreds of square miles, 1 is not recognizable by any conspicuous unconformity 

in Britain. But the sudden incoming of the Callovian fauna in the 

middle of the Cornbrash, the upper half of the Cornbrash containing the new 

Callovian and the lower half the old Bathonian fauna, while the two divisions 

are almost perfectly conformable, is probably due to the submergence of 

barriers and accelerated migration attendant on the Callovian Transgression. 

The greatest transgression of Jurassic times in North-west Europe, the 

Rhaetic, was accompanied by very little overstep or discordance. The Triassic 

salt-lakes were already at or below sea-level and the Rhaetic sea merely flow r ed 

uniformly over them, distributing the same fauna from Germany to Dorset 

and the North of Scotland. 

The type of phenomenon exemplified by the Rhaetic Transgression may be 

distinguished as 'conformable transgression', the other as unconformable. 

The two different types are complementary manifestations of the same event, 

consequent on the previous history of the terrain invaded. 

Just as transgressions should be distinguished from the effects of local 

orogenic movements, so too should regressions. Transgressive formations, 

such as the Callovian or Cretaceous, may rest non-sequentially or with slight 

unconformity upon much older Jurassic or Palaeozoic beds over hundreds 

of square miles, as does the Cretaceous in the northern half of the British 

Isles. In all the counties north of Bedford Cretaceous rocks repose on 

Kimeridge Clay or older beds, and no sign of Portland or Purbeck Beds 

is found. It is highly improbable that had these last ever been deposited 

they could have been so completely removed as to leave no vestige behind 

throughout the long outcrop from Cambridgeshire to Yorkshire or in Scotland. 

It seems much more likely that the whole of Northern Britain received 

an upward tilt about the end of the Kimeridge period, which brought sedimentation 

to a standstill. Detailed correlation of the Portland and Purbeck 

Beds of Oxon. and Bucks, with those of Dorset reveals that each subdivision 

of the formations thins out northward and would soon disappear beyond the 

present outcrops, without the aid of any subsequent erosion. 2 We seem, 

therefore, to be dealing with a regional upward warping, causing a regression 

of the sea—a truly epeirogenic event. Dr. Versey has attempted to correlate 

the movement with the Younger Cimmerian movements in North-west 

Germany, but he seems to me to be dealing with two different classes of 

phenomena. 3 In order to find the counterparts of the Younger Cimmerian 

movements we ought to study the tectonics of the South of England, where 

sedimentation was proceeding all the time they were in operation. 

It may be useful to review very briefly the principal examples of unconformable 

transgressions, with their pebble-beds and allied phenomena, observed 

in the British Jurassic rocks, noticing which seem to have been preceded by 

orogenic activity. 

1 E. Haug, 1911, Traite, pp. 1002-3 ; and Suess, Face of the Earth, vol. ii, p. 273. 

2 More will be found on this subject at the beginning of Chapter XVII. 

3 H. C. Versey, 'Saxonian Movements in East Yorkshire', Proc. Yorks. Geol. Soc., vol. xxii, 

p. 57. In interpreting the term Tortlandian' it should be noted that, so far from the Osterwald 

and Deister Phases having taken place at the time of our Portland Beds (Portlandian as understood 

in England), one occurred in the Lower Kimeridge and the other in the Middle Purbeck 

(see below, Chap. XVII).

SUMMARY OF TECTONIC HISTORY 93 

SUMMARY OF THE PRINCIPAL TRANSGRESSIONS RECOGNIZABLE IN THE 

ENGLISH JURASSIC 1 

(Details will be found in the Stratigraphical Part of the Book.) 

Rhaetic Beds. 

The great Rhaetic Transgression has already been mentioned, and this 

seems to have coincided with the close of the Older Cimmerian orogenic 

phase, but folding in Britain was only slight. Minor disturbance continued, 

as we have seen, along several of the axes until the end of the period. 

Lower Lias. 

During the early part of Lower Lias times a series of small folds arose 

on the north of, and parallel with, the Mendip Axis, their crests undergoing 

repeated erosion. The bucklandi zone transgresses across all these until it 

comes to rest on Rhaetic White Lias about Radstock. Similar movements 

doubtless occurred along the other axes, where the formation is much thinner 

than the normal, but lack of exposures prevents investigation (see p. 131). 

In Scotland the semicostatum zone overlaps the earlier beds in Skye and 

comes to rest on Cambrian limestones on the shores of Loch Slapin. 

In Kent and in Buckinghamshire (as proved by the Calvert Borings) there 

is an overlap, perhaps indicative of a minor transgression, of thc jamesoni zone 

on to the Palaeozoic Platform. 

Inferior Oolite. 

The scissum zone is transgressive for some hundreds of miles across 

different members of the Whitbian, from Oxfordshire through Northants.and 

all Eastern England to Yorkshire. Chiefly on this account it has been selected 

here as the base of the Inferior Oolite, though the rarity of the zonal index 

fossil in Northants. and its gradual disappearance northwards suggests that 

there is some overlap, the basal member, with its pebble-bed, probably being 

slightly diachronic. In Yorkshire it may be of either Ancolioceras or murchisonae 

date. This transgression seems to be quite independent of the axes. 

The discites zone (the basal zone of the Bajocian sensu stricto) is discordantly 

related to the Aalenian Stage in Dorset, Somerset and the Cotswolds, and in 

Dorset it has a conglomeratic bed at the base. There are indications that the 

same zone overlaps the Aalenian in North Lincolnshire; and in Yorkshire 

the transgression is marked as the most important of the marine interludes in 

the Estuarine Series by the Millepore Bed and Cave and Whitwell Oolites. The 

transgression was preceded by activity along the Birdlip Axis in the Cotswolds 

and probably also along several of the other axes. 

The garantiana and truellei zones (Lower Vesulian) are highly unconformable 

with the underlying beds from Dorset to Oxfordshire. They mark one 

of the most important transgressions of Jurassic times; but in England the 

spectacular effects are greatly increased owing to the transgression having 

been preceded by a period of profound orogenic activity. All the axes of 

Armorican (E.-W.) directrix were uplifted and their crests eroded before the 

transgression. A sudden deepening of the sea seems to have taken place also 

1 It is not possible here to distinguish all the conformable transgressions.

94 C O N T E M P O R A N E O U S T E C T O N I C S 

in the Hebrides, where the garantiana zone coincides with an abrupt change 

of lithology, from several hundreds of feet of sandstones to black shale. 

Great Oolite Series. 

The Great Oolite Series is highly transgressive eastwards over the London 

landmass. The lowest divisions, the zigzag and fnsca zones (equivalents of 

the Chipping Norton Limestone), overlap the Inferior Oolite in Oxfordshire 

before reaching the Cherwell Valley, and they are in turn overlapped by the 

middle portion of the series (including the Great Oolite limestone) all along 

the eastern outcrop from the neighbourhood of Northampton northwards. 

The middle and upper portions of the series transgress over the Palaeozoic 

platform as'far as London. 

There are local overlaps and oversteps within the series, such as those which 

cause the appearance and disappearance in short distances of the Stonesfield 

Slate Series and the Wychwood Beds in Gloucestershire and Oxfordshire. 

The Lower Cornbrash seems to overstep the Wychwood Beds towards the 

north and east, reducing them from perhaps 90 ft. to nothing between Wiltshire 

and East Oxfordshire. Farther north the Upper Cornbrash oversteps 

(or overlaps) the Lower and in Yorkshire it becomes a transgressive stratum 

resting on the Estuarine Series; over most of England, however, the Upper 

Cornbrash is perfectly conformable with the Lower, marking only a conformable 

transgression. 

Oxford Clay and Corallian. 

Considerable elevatory movements took place at the time of the Oxford 

Clay in the Hebridean area of Western Scotland, but the details have not 

been worked out (see pp. 370-2). 

One of the most remarkable pebble-beds in the Jurassic System occurs in 

the Corallian of the Midlands, at the base of the Berkshire Oolite Series 

(martelli zone). It is continuous for more than 40 miles, from near Calne in 

Wiltshire to Oxford, and indicates a widespread epeirogenic movement like 

that which heralded the Inferior Oolite. Beyond Oxford the same horizon 

continues to be related non-sequentially, and with signs of erosion, to the 

Lower Calcareous Grit and Oxford Clay, which it oversteps eastward. North 

of Cambridge there is probably also an overlap of the Berkshire Oolite Series 

by higher parts of the Corallian Beds developed in clay facies. 

At Oxford and around Wootton Bassett, Wiltshire, the Corallian Beds show 

unmistakable signs of local uplift and non-deposition or erosion, apparently 

unrelated to the more general movements and of orogenic type. 

Kimeridge Clay and Portland Beds. 

According to Salfeld's identification of Gravesice both in the Gigas Beds of 

Germany and in the clays of the lower part of Hen Cliff, Kimeridge, Dahlgrlin's 

Deister Sub-Phase of the Younger Cimmerian movements took place 

during the deposition of the Lower Kimeridge Clay (not the 'Portlandian'). 

We should look for signs of it in England between the Gravesia and the Aulacostephanus 

zones, but so far no indications of discordance at that horizon have 

been recorded. The Gravesia zones often seem to be absent, and indeed their 

presence anywhere in England except Dorset is a matter of doubt; but this does

SUMMARY OF TECTONIC HISTORY 95 

not signify movements contemporaneous with the 'Deister Phase', for in 

North-west Germany it is the Gravesia zones that are transgressive and zones 

below and above that are wanting. 

Two widespread pebble-beds, coinciding with considerable non-sequences, 

occur higher up in the series, from Wiltshire to Buckinghamshire. The first, 

known as the Lower Lydite Bed, appears at the base of the rotunda zone at 

Swindon and continues past Oxford into Bucks. It marks the disappearance 

of at least some of the 240 ft. of clays between the oil-shale and the rotunda 

zone on the Dorset coast. The second, the Upper Lydite Bed, first appears 

in the Vale of Wardour and also continues to Bucks. Its stratigraphical 

position is somewhere in the middle part of the Portland Sand of the South, 

and it too cuts down transgressively, so that almost as great a thickness of 

sands and clays is missing. Both of these pebble-beds denote epeirogenic 

movements and they seem to be connected with the proximity of the London 

landmass, whence their materials were probably derived (see pp. 514-15). 

The regional warping that set in early in Kimeridge Clay times and by the 

end of the period put a stop to sedimentation in North Britain has already 

been mentioned. After the deposition of the Portland Stone a barrier was 

raised which cut off the South also from the open sea, and the peculiar conditions 

of the Purbeck period reigned in Southern England and North-west 

Germany, although subsidence continued in both areas. 

Purbeck Beds. 

In the Middle Purbeck the sea advanced simultaneously in Kent and 

Dorset and inland at least as far north as Mid-Wiltshire. This advance, a 

conformable transgression, seems to have been beyond much doubt contemporaneous 

with the unconformable transgression of the Serpulite in Northwest 

Germany (the argument for this correlation is given in Chapter XVII, 

pp. 550-1). The causes of the discordant oversteps in Germany were the 

orogenic movements of Dahlgriin's 'Osterwald Phase', which do not seem to 

have operated in England. Here then, is a good illustration of the distinct 

effects produced by the same marine transgression, in regions which have and 

have not been first subjected to orogenic folding. Where the area invaded is 

already at sea-level, as in South England, there is perfect conformity in spite 

of a sharp change from fresh-water to marine fossils; where there has been 

orogenic activity locally, as in North-west Germany, the transgressive bed 

oversteps the folded strata and an unconformity results. 

Post-Jurassic and Pre-Aptian Movements. 

Earth-movements of both epeirogenic and orogenic types took place extensively 

all over the British Isles before both the Aptian and the Albian 

transgressions. The history of events during the transition from Jurassic to 

Cretaceous times will be traced in Chapter XVII, and so little need be said 

here, beyond pointing out that these movements were probably greater than 

any that occurred during the Jurassic period, and were moreover accompanied 

by extensive faulting. In Dorset, in a belt of country lying north of the Weymouth 

Axis, around Charmouth and Bridport, the Jurassic rocks are torn by 

numberless faults, of almost every strike, the key-lines however trending 

E.-W. In Watton Cliff one of these faults throws Forest Marble against


Middle Lias and at Burton Bradstock another throws Forest Marble against 

Upper Lias (Bridport Sands). North-eastward the system of faults passes 

under the overstepping Gault and Chalk without affecting them in the 

smallest degree. Under the Gault at Abbotsbury there is a fault of 600-700 

ft., throwing down Kimeridge Clay against Forest Marble. 1 Still farther east 

is the fault in Ringstead Bay, already mentioned, where the Purbeck Beds are 

seen to be affected, but not the Gault. As the Wealden Beds are everywhere 

perfectly conformable with the Purbecks, these faults can be said to be post- 

Neocomian and pre-Albian. 

Inland there is evidence that considerable faulting was not only pre- 

Albian but also pre-Aptian. This can be seen near Calne, between Bromham 

and Seend, where the Lower Greensand crosses a fault from Kimeridge Clay 

on to Lower Corallian Beds. 2 

Instances of unconformity between Jurassic and Aptian beds are too 

numerous to mention, for wherever we examine the relations of the two 

formations it is evident that great earth-movements supervened between 

them. Something will be said on the meaning of these movements in Chapter 

XVII. Meanwhile we must pass on to the next and most important part of 

our theme, the stratigraphy. 

1 Figured in Whitaker and Edwards, 1926, 'Water Supply of Dorset', p. 4, Mem. Geol. 

Surv. 

2 H. J. Osborne White, 1925, 'Geol. Marlborough', Mem. Geol. Surv., p. 8.

PART III 

STRATIGRAPHY 

CHAPTER IV 

RILETIC BEDS 

Strata Thickness Principal Fossils (Plate XXIX) 

WATCHET BEDS 0-8' Modiola langportensis Rich. & Tutch. 

LANGPORT BEDS 

Ostrea liassica Strickland 

Dimyodon intus-striatus (Emmr.) 

1 Modiola langportensis Rich. & Tutch. 

or 

WHITE LIAS (sensu stricto) 

0-25' 

Ostrea liassica Strickland 

Dimyodon intus-striatus (Emmr.) 

COTHAM BEDS 0-19' Pseudomonotis fallax (Pfliicker) 

Ostracoda 

Estherice and Lycopodites 

WESTBURY BEDS or CONTORTA 

SHALES 

i-47' Pteria contorta (Portlock) 

Cardium cloacinum Quenst. 

Chlamys valoniensis (Defr.) 

Vertebrata (esp. Ceratodus) 

SULLY BEDS (fossiliferous top 

0-14' Ostrea bristovi Etheridge 

portion of the Grey Marls) 

IT is now generally agreed that the Rhaetic Beds are best classed as the basal 

member of the Jurassic System. 2 The old classification, which regarded 

them as part of the Trias, draws, at least in North-west Europe, an unnatural 

line of division between the Rhaetic and the Lias, while ignoring a slight 

but widespread unconformity, coincident with an important and ubiquitous 

change of lithology, between the Keuper and the Rhaetic. There is no datum 

so suitable for starting the Jurassic System as that marked by the Rhaetic 

Transgression, the effects of which are marked all over North-west Europe. 

Thanks principally to Mr. L. Richardson's detailed studies, spread over the 

last thirty years, a great deal is now known of the Rhaetic rocks of Southern 

and Central England. These studies have tended to accentuate the importance 

of the break at the top of the Keuper. Richardson has shown that the Keuper 

Marls, in West and Central England, were arched up into a series of gentle 

flexures before the Tethyan sea advanced from the south over the desert 

plains and salt lakes and submerged them. The first Rhaetic sediments were 

laid down in the hollows between the folds, and it was not until later that the 

crests sank also beneath the sea. 

Wider knowledge of other parts of the Jurassic System, too, has thrown new 

light on the origin of the famous Bone Bed at or near the base of the Rhaetic. 

As Strickland first suggested many years ago, 3 this stratum probably results, 

1 The term 'Langport Beds* was suggested by Richardson to replace 'White Lias' because 

the latter was used inconsistently—sometimes for true White Lias, sometimes for White 

Lias plus Cotham Beds, and at other times for Cotham Beds. It was originally introduced for 

the whole 'Upper Rhaetic' by William Smith (see p. 4). 

2 Unless, as some have suggested, they be considered to form a diminutive system of their own. 

3 Memoir of H. E. Strickland, 1858, pp. 157-8; and see L. Richardson, 1904, Q.J.G.S. 

vol. lx, p. 354. The idea is also adopted by L. J. Wills, 1929, Phys. Evol. Britain, p. 132.

ioo RHAETIC BEDS 

not from any sudden massacre of vertebrates or temporary abundance of 

vertebrate life as has been so often supposed, but from slowness of sedimentation. 

Comparable fossil-beds in other parts of the Jurassic Series, such as 

those composing much of the Inferior Oolite in the Dorset-Somerset area, or 

the Cephalopod Beds at the top of the Upper Lias of the Cotswolds, are now 

known to be natural segregations. They were accumulated over a long period 

of time, during which life flourished normally, but either little sediment was 

present to entomb the remains, or currents carried it continually away. It is 

now accepted, therefore, as indication of a prolonged pause in early Rhaetic 

times. 

I. THE DEVON-DORSET-W. SOMERSET AREA 

(a) The Devon-Dorset Coast. 1 

A complete though discontinuous section of the Rhaetic Beds is exposed 

in the cliffs of Culverhole Point, near the border between Devon and Dorset. 

The Upper Rhaetic is again exposed in Charlton and Pinhay Bays to the east, 

between Culverhole Point and Lyme Regis (Plate I). The total thickness is 

about 47 ft. 

The Keuper Red Marls pass up into about 75 ft. of grey-green marls known 

as the Tea Green Marls, which have in the past been called the Transition 

Beds, and variously assigned to the Keuper and to the Rhaetic. They yield no 

fossils. At the top are widespread signs of erosion before the deposition of 

the Westbury Beds or Contorta Shales. Mainly on this evidence, Richardson 

assigns the Tea Green Marls to the Keuper and considers that there is a nonsequence 

at the base of the Rhaetic, some fossiliferous grey marls (Sully 

Beds), which appear in the neighbourhood of the Bristol Channel, being 

unrepresented. 

The top of the Rhaetic too, consisting of the limestone of the White Lias, 

is bored and eroded, this erosion having destroyed the Watchet Beds of 

North Somerset. 

SUMMARY OF THE SEQUENCE ON THE DORSET COAST 

Langport Beds or White Lias (sensu stricto)y 25 ft.: 

Thin beds of white limestones, here and there false-bedded, the top layer 

massive and brownish, with the upper surface bored to a depth of 1 or 2 in., 

and some other irregular and apparently bored surfaces in the lower part. In 

the middle and upper portions Ostrea lias sic a, Protocardia> Dimyodon intusstriatus, 

and a few ill-preserved fragments of other fossils occur. The upper 

part of this division and the junction with the Blue Lias may be studied to 

advantage on the east side of Pinhay Bay, in a long exposure at the foot of the 

cliff (Plate I). 

Gotham Beds, 5 ft.: 

The Cotham Marble is an impersistent, pale greenish-grey limestone, only 

from 1 \ to 8 in. thick, at the top of the division. It is slightly pyritic and 

arborescent. The rest of the beds below are made up of dark shales with two 

1 Based on L. ^Richardson, 1906, 'On the Rhaetic and Contiguous Deposits of Devon and 

Dorset', P.G.A., vol. xix, pp. 401-9.

Photo. 

Cliffs of Blue Lias and White Lias, Pinhay Bay, Lyme Regis, 

PLATE I

PLATE II 

Photo. 

Photo. 

Garden Cliff, near Westbury on Severn, Glos. 

Sidney Pitcher. 

Showing Rhastic Beds with two prominent bands of Pullastra sandstone in the 

lower part, resting on the Tea Green Marls of the Keuper. In the lower 

photograph fallen blocks of the sandstone show ripple-marks. The cliff in the 

distance is composed of red and green Keuper Marls capped by Tea Green 

Marls. 

Sidney Pitcher.

RHAETIC: DEVON-DORSET COAST 99 

thin limestone seams. The shales yield Ostracods (.Darwinula), fish-scales, 

saurian coprolites, and Cardium cloacinum. 

Westbury Beds or Contorta Shales, 17 ft.: 

Black and brown fossiliferous shales with three thin limestone seams. The 

shales are laminated and contain much selenite, and yield the following fossils: 

Pteria contorta (very abundant), Chlamys valoniensis, Myophoria emmrichi, 

'Schizodus' ewaldiy 1 Placunopsis alpina, Protocardia rhcetica, Pleurophorus 

elongatus; also the fish Acrodus minimus and Gyrolepis alberti. At the base is 

the BONE BED, 2 in. thick, consisting of indurated, gritty, black shale, full of 

small bones, scales and teeth of Gyrolepis alberti, Acrodus minimus, Saurichthys 

acuminatus, ?*Sargodon, Lepidotus and Hybodus, with coprolites. 

[Eroded surface of Tea Green Marls; Sully Beds and certain of the lower 

beds of the Contorta Shales missing.] 

(b) West Somerset 

The Devon and Dorset outcrop of the Rhaetic runs north to the neighbourhood 

of Chard, where it is concealed for a short distance by the Cretaceous rocks. 

On emerging from beneath the Blackdown Hills it strikes in a low ridge northwestward 

to Langport and Somerton, thence circling round King's Sedgmoor 

north-eastwards, beneath the Blue Lias of the Polden Hills, to the coast 

at Watchet. Between the Polden Hills and the Mendips the Rhaetic rises 

through the alluvium in several places near Wedmore. 

This part of the outcrop contains several fine sections, notably those on the 

coast at Blue Anchor Point, St. Audries' Slip and Lilstock, all near Watchet, 

railway-cuttings at Puriton and Charlton Mackrell at either end of the 

Polden Hills, Langport railway-cutting, and a number of minor exposures and 

quarries. At Charlton Mackrell at the SE. end of the Polden Hills, the total 

thickness is 47 ft., as in Dorset; but towards the south the beds grow thinner, 

while towards the coast they become considerably thicker and the Watchet 

Beds appear above the White Lias and the Sully Beds below the Contorta 

Shales. The succession may be summarized as follows: 

SUMMARY OF THE RHAETIC SUCCESSION NEAR WATCHET 2 

Watchet Beds, 0-8 ft.: 

Marls and Shales with inconspicuous layers of impure limestone, containing 

occasional specimens of Ostrea liassica and Modiola langportensis. These 

are best developed in the coast sections at Watchet, to which neighbourhood 

they are restricted. Over the rest of the area the paper-shale at the base of 

the Lower Lias lies non-sequentially on the Langport Beds. 

Langport Beds or White Lias ($.$.) 

The thickest development in the district is at Charlton Mackrell at the SE. 

end of the Polden Hills, where the White Lias is 20 ft. 8 in. thick. The 

mamillated and often bored upper surfaces of the limestone courses, their 

1 See note opposite Plate XXIX, fig. 10, at the end of the book. 

2 Based on L. Richardson, 1911, Q.J.G.S., vol. lxvii, pp. 1-55; and 1914, P.G.A., vol. xxv, 

pp. 97-io2>


irregular under-surfaces, and irregular, rubbly and conchoidal fracture, 

indicate a slow rate of formation. Near the middle of the series at Charlton 

Mackrell is a coral limestone, 16 in. thick, full of Thecosmilia? michelini 

Terq. and Piette, associated with numerous Ostrea liassica. Towards the 

north-west the Langport Beds thin out. In the Dunball railway-cutting near 

Puriton, at the other end of the Polden Hills, they are reduced to 4 ft. 3 in., 

while on the coast they have still further dwindled, measuring less than 4 ft. at 

Lilstock and only 2 ft. 3 in. at Blue Anchor Point. Here all that is left is four 

thin bands of limestone. 

Palaeontologically the Langport Beds of Somerset resemble those of Dorset. 

Dimyodon intus-striatus appears in great force, and Modiola langportensis, 

Ostrea liassica, Lima valoniensis and internal casts of Cardinia and Protocardia 

abound, but are of no zonal value. 

Cotham Beds. 

This division is much the same as in Dorset, usually from 5 ft. to 7 ft. thick, 

consisting of pale marls with at least three thin limestone bands, the Cotham 

Marble being sometimes represented at the top, rich in Pseudomonotis fallax. 

Ostracods and Estherice are common. 

Westbury Beds or Contorta Shales. 

This division thickens towards the coast at Watchet proportionately as the 

White Lias becomes thinner. At Langport and Charlton Mackrell it measures 

22-3 ft., but at Lilstock a measurement of 32 ft. was obtained, and at Blue 

Anchor Point 46 ft. In lithic characters the Contorta Shales resemble those 

of Dorset, except that at Langport three thin bands of sandstone appear near 

the base. The general facies is sub-littoral and the mollusca are usually 

dwarfed. 

In the upper part of the series mollusca abound, particularly Pt. contorta, 

Chi. valoniensis and Dimyodon intus-striatus. In the west there is often a 

Pleurophorus bed, and another characterized by Cardium cloacinum Quenst. 

In the lower part of the series vertebrate remains predominate, occurring at 

several horizons. But the chief bone bed, which contains Ceratodus at Blue 

Anchor Point, instead of forming the base, is found up to 22 ft. higher. 

Another bone bed, 2 in. thick, takes its place at the base, yielding Acrodus 

minimus, Gyrolepis alberti, Saurichthys acuminatus Ag., Hybodus minor, Sargodon 

tomicus Plieninger, and Lepidotus. 

Sully Beds. 

These beds are merely the uppermost 14 ft. of the Grey Marls, formerly 

classed with the Keuper, and always separated from the basal Bone Bed of the 

Contorta Shales by a surface of erosion. But in the neighbourhood of Watchet, 

where the Contorta Shales are thickest, higher horizons of the Grey Marls are 

preserved, and Rhaetic fossils occur in them down to 14 ft. below the basal 

Bone Bed. These fossiliferous upper portions of the Grey Marls are best 

developed at St. Mary's Well Bay near Sully, on the opposite side of the 

Bristol Channel, after which Richardson has named them the Sully Beds. As 

long ago as 1864 the late Sir W. Boyd Dawkins insisted that these marls with 

Rhaetic fossils, although they occurred below the Bone Bed, should be classed

RH/ETIC: GLAMORGAN 101 

with the Rhaetic. 1 In the Watchet coast-sections Pt. contorta, Gervillia precursor, 

Chi. valoniensis and other fossils have been found down to 14 ft. below 

the Bone Bed, and at a depth of 10 ft. 6 in. Sir W. Boyd Dawkins found the 

earliest known mammal, the small Hypsiprymnopsis rhceticus, 2 in association 

with Acrodus minimus, Sargodon tomicusy scales of Gyrolepis spp., and a Pterodactylian 

bone. 

(c) The Glamorgan Coast. 3 

The former continuation of the West-Somerset Rhaetic Beds across what 

is now the Bristol Channel is proved by the exactly comparable sections in 

the cliffs between Cardiff and Barry. The finest sections are at Lavernock 

Point and the type locality of Sully, at Penarth, and in the cliff facing Barry 

Island, near Coldknap Farm, at which last place only the White Lias is well 

seen. 

The basal Bone Bed of the Westbury Beds or Contorta Shales at Lavernock 

has long been known under the name of the 'Fish Bed', and besides the species 

recorded at Watchet, it yields Saurichthys acuminatus Ag., Hybodus minor Ag., 

and H. cloacinus Quenst. It rests on a conspicuously waterworn surface of 

the Sully Beds, filling hollows in them to a depth of up to 5 in., and sometimes 

containing pebbles of argillaceous stone. The Sully Beds consist of grey marl 

and bands of hard grey marlstone. The boundary betw r een them and the 

Tea Green Marls is drawn arbitrarily at about 14 ft. below the Fish Bed, 

this being the lowest occurrence of Rhaetic fossils. At a depth of about 6 ft. 

have been found remains of the Labyrinthodon Mastodonsaurus, a mandible 

and two teeth, believed to belong to Palceosaurus, bones of Trematosaurus, 

and numerous small teeth of Sphcerodus. 

As in the Watchet district, a second bone bed occurs in the Contorta 

Shales, containing vertebrae of Plesiosaurus. At Lavernock it is only 1 ft. 

above the base. A few inches higher is a layer with hundreds of teeth of 

Acrodus minimus and scales of Gyrolepis alberti. But the most persistent 

strata are two Pecten-beds in the upper part, full of ChL valoniensis and the 

other mollusca common in Somerset. 

The Cotham Beds and White Lias are thinner than at Watchet, measuring 

only about 3 ft. and 2 ft. 6 in., but palaeontologically and lithologically they 

are typical. The White Lias is especially fossiliferous at Coldknap, Barry. 

At the top, overlain by the paper-shales of the Lower Lias, are the Watchet 

Beds, similar to those at the type locality, just over 6 ft. thick at Lavernock, 

9 ft. thick at Barry. 

II. THE LITTORAL OF THE SOUTH WALES COAL-FIELD 

Inland towards Cowbridge, in the Vale of Glamorgan, the Rhaetic Beds show 

signs of proximity to the shore-line of the South Wales highland. The edge 

of the Upper Carboniferous rocks forming the rim of the coal-field still rises 

as a wall high above the Vale of Glamorgan, but when the Rhaetic waters 

1 W. B. Dawkins, 1864, Q.J.G.S., vol. xx, p. 408. 

2 Formerly known as Microlestes. See W. B. Dawkins, 1864, loc. cit., pp. 409-12. 

3 L. Richardson, 1905, Q.J.G.S., vol. lxi, pp. 385-425; F. F. Miskin, 1922, Trans. Cardiff 

Nat. Soc., vol. lii, pp. 23-5, gives a different interpretation of the Rhaetic base.


lapped against its foot, along a line now raised to 400 ft. above the sea, its 

elevation must have been many hundreds of feet greater (fig. 16). 

In Triassic times an elongate island of Carboniferous Limestone, thrown up 

by an E.-W. anticline, ran off-shore from near the mouth of the present 

River Ogmore to north-east of Cowbridge, where it broke up into two tongues. 

Between the tongues, at their extremities, would have lain the city of Llandaff. 

During the Rhaetic transgression the Keuper Marls were overlapped and 

much of the eastern end of the island became submerged. It was not yet 

FIG. 16. Sketch-map showing the geography of the neighbourhood of Cowbridge Island 

at the end of the Triassic period. From Strahan and Cantrill, 4 Geol. S. Wales Coal-field \ 

part vi, p. 24, fig. 2. Mem. Geol. Surv. 

completely covered, however, and it continued to form a barrier between the 

shore and the open sea to the south. In the channel between the north shore 

and the mainland were collected most of the sandy sediments brought down 

by the rivers from the Welsh mountains. 

The first signs of shore-deposits in the Rhaetic succession are met with in 

the neighbourhood of Cowbridge. At Bonvilston, on the southern edge of 

the old island, and at Pendoylen and other places to the east, normal black 

shales and shelly limestones still prevail. At Cowbridge, for the first time in 

passing westward, the Contorta Shales contain bands of grey sandstone and 

also an 8-inch band of hard conglomerate. It is an interesting indication of 

the prevailing currents that the constituents of these sandstones were drifted 

round the western end of the Carboniferous Limestone island. 

The best sections in the Cowbridge district are in the Tregyff road- and 

railway-cuttings, where the Westbury Beds are highly fossiliferous. Richardson 

has identified a limestone and marlstone below, yielding Acrodus and 

Sargodon, which he correlates with the Sully Beds. The total thickness of the 

Rhaetics from the top of the Tea Green Marls to the paper-shale at the base of 

the Lias is IQ ft. 1 

1 L. Richardson, 1905, Q.J.G.Svol. lxi, pp. 400-2.

RHiETIC: SOUTH WALES LITTORAL 103 

In the channel between the north side of the island and the mainland, the 

Rhaetic Beds present an entirely different appearance. The upper parts of the 

formation are represented by red-streaked greenish marls and shales, greatly 

reduced in thickness, while the lower parts pass entirely into sandstones, 

which at Hendre, near Pencoed, and other places, are as much as 30 ft. thick. 

At Quarella Quarry, Bridgend, the Rhaetic sandstones are quarried for 

building, and are seen in an unbroken succession to a thickness of 24 ft. For 

the most part they are white, fine-grained and massive below, and more thinbedded 

above. It is probable that the whole of the Rhaetic Series is represented 

in these sections. The uplands of Stormy Down and St. Mary Hill Down, 

which are strewn with large masses of the sandstone, resemble moorlands of 

Millstone Grit. 

In the sandstone at Stormy Down have been found Hybodus,*Schizodus\ 

Myophoria and a few other mollusca, and a jaw of a large megalosaurian reptile, 

Zanclodon (}Avalonia) cambrensis Newton. The associated marl beds yield 

Pt. contorta. 1 

The final stage of the littoral deposits is seen in an actual beach of Rhaetic 

age on Cae Tor, near Pyle, capped by the Oyster Beds at the base of the Lias. 

The beach material was described by the late Sir Aubrey Strahan as a 'coarse 

calcareous grit with a few pebbles, in close association with a shelly and detrital 

limestone containing fragments of corals, molluscs and echinoderms, together 

with small fragments of an older granular limestone and grains of 

quartz'. 2 It rests upon or close above Triassic conglomerate and thins out 

within a few yards to the south, against the Cowbridge Island. 

III. THE MENDIP ARCHIPELAGO 3 

The Cowbridge Island was one of an archipelago of Carboniferous Limestone 

islands which lay off the shore of the South Wales mountains in Rhaetic 

and Liassic times. They dotted the sea on both sides of what is now the Bristol 

Channel, and although they have since been completely submerged and were 

covered up with later Jurassic and Cretaceous sediments, Tertiary and 

Quaternary denudation has stripped them bare once more, so that most of 

them now rise above the Triassic and Liassic plain as prominent hills. 

The principal limestone masses were the ridge of the Mendips and the other 

Carboniferous inliers of Kingswood, Clifton, Clevedon, Wrington and Cowbridge 

(fig. 17). Lesser islets can be recognized in Worle Hill, Brean Down, 

and the Steep Holm and Flat Holm rocks, between Weston and Barry. These 

last have reverted to their original condition of islands, being now surrounded 

by the waters of the Bristol Channel. 

While the mainland provided a catchment area for rivers and streams, 

which, as we have seen, brought down large quantities of sand and detritus 

from the Millstone Grit and Coal Measures of South Wales, to pour 

them into the Rhaetic sea, the islands had little effect on the sedimentation. 

The Rhaetic Beds deposited in the channels among the archipelago are thinner 

1 L. Richardson, 1905, loc. cit., pp. 406-10; E. T. Newton, 1899, Q.J.G.S., vol. Iv, 

pp. 89-96. 

2 A. Strahan, 1904, 'Geol. S. Wales Coal-field, part vi, Bridgend', Mem. Geol. Surv., p. 54. 

3 L. Richardson, 1903, 'The Mesozoic Geography of the Mendip Archipelago', Proc. 

Cots. N.F.C., vol. xiv, pp. 59-72.


than elsewhere, but their facies is much the same as that of the beds formed 

in more open water to the south and west. The most noticeable change of 

facies is from shales to limestones, the lime being supplied by solution and 

redeposition from the limestone cliffs and screes. 

The normal clays and shales can sometimes be seen passing surprisingly 

close to the old shore-lines, limestones and conglomerates taking their place 

FIG. 17. Sketch-map of the Mendip Archipelago at the time of the Rhaetic Transgression. 

Thick lines represent the presumed pre-Rhaetic coastline; thin lines show the present coastline 

of the Bristol Channel. Mainly after Lloyd Morgan, Strahan and Cantrill. 

only where the beds actually abut on the Palaeozoic surface. Perhaps the best 

idea of this is to be obtained near Shepton Mallet. In the railway-cutting by 

the Three-Arch Bridge, south of the town, the Rhaetic Beds are 28 ft. thick 

and contain the usual fossils. The Westbury Beds at the base consist as usual 

of n | ft. of black shales, and the Langport Beds or White Lias at the top 

comprise 12 ft. of the normal cream-coloured limestones. Only the Cotham 

Beds in the centre, though mainly shales, contain a thin band of conglomerate, 

2 in. thick, formed of pebbles of Carboniferous Limestone. 1 

Less than a mile to the north, near the viaduct south of Downside, the 

1 L. Richardson, 1911, Q.J.G.S., vol. lxvii, p. 60; and to the end of this section, based on 

op. cit., pp. 55-72.

RH/ETIC: MENDIPS 105 

Rhaetic is represented only by a breccio-conglomerate, resting on the planed 

surface of the Carboniferous Limestone, and overlain by a massive sparry 

limestone representing the base of the Lower Lias. The constituents of the 

conglomerate are limestone and chert derived from the Carboniferous, 

embedded in a grey matrix, which yields Pt. contorta, vertebrae of Plesiosaurus, 

teeth of Saurichthys, Sargodony Lepidotus, Acrodus and Gyrolepis, coprolites, 

small quartz pebbles, and reptilian bones. 

The same rapid change of facies may be seen at various places round the 

eastern end and northern flank of the Mendips. Vallis Vale, cutting from the 

Frome Valley north of Frome westwards into the end of the Mendips, provides 

fine sections of attenuated Rhaetic, Liassic and Inferior Oolite strata 

thinning out against the rising surface of the Carboniferous Limestone (map, 

fig. 13, p. 70). About 2 miles north-west of Frome the Rhaetic, with the Bone 

Bed at the base, is normal. At Hapsford Mills it is 14J ft. thick, consisting of 

alternate bands of conglomerate and clay in the lower part, and of conglomerate 

and limestone in the upper, with fish teeth at the base. A very short 

distance nearer the shore-line it is 4 ft. thick, consisting mainly of conglomerate, 

with thin seams of clay and some limestone and nodules, the whole 

richly fossiliferous. Many of the limestone pebbles are bored by Polydoray l 

and in the shales Charles Moore found specimens of Eolepas and Chiton. 

At both these places the base is cemented firmly on to an eroded surface of 

Carboniferous Limestone, while the top is in turn eroded and well bored and 

directly overlain by the Upper Inferior Oolite. In a similar section at Holwell 

the Rhaetic is only 1 ft. thick, but contains numerous characteristic fossils. 

Charles Moore made Holwell famous by the discovery of about 70,000 teeth 

and small bones of vertebrates, among which were 29 teeth of mammals, now 

assigned to the genera Microcleptes and Thomasia. The remains were collected 

in fissures in the Carboniferous Limestone. 2 

Similar patches of Rhaetic shore-deposits, which may or may not be covered 

by attenuated representatives of the Lias, are seen resting in hollows of 

the Carboniferous Limestone floor at Vobster, Harptree and elsewhere. At 

Harptree they are arenaceous, owing to the proximity of Old Red Sandstone. 

Vertebrate remains are often numerous in fissures in the underlying Carboniferous 

Limestone. 

At Nempnett some small outliers provide a glimpse of the beds laid down in 

one of the channels between the islands: to the south lie the Mendips, to the 

north Wrington Island, the channel between them being about 3 miles wide. 

In the middle of this channel lie the Nempnett outliers of Rhaetic Beds resting 

on the Tea Green Marls. From the base upwards, massive conglomerates 

replace the greater part of the Westbury Beds, Cotham Beds and Langport 

Beds. They are composed of pebbles of Carboniferous Limestone embedded 

in a matrix of shell debris and calcite, through which are sparsely distributed 

fish-scales and teeth, coprolites, and fragments of bone. At intervals normal 

shale and limestone are interbedded and yield the characteristic Rhaetic 

fossils. At one place there is a Chi. valoniensis limestone. No Watchet Beds 

1 F. A. Bather, 1909, Geol. Mag. [5], vol. vi, p. 109. 

2 For a revision of the stratigraphy, a description of the circumstances of the find and 

references to all previous literature see L. Richardson, 1911, loc. cit., pp. 62-4; also G. G. 

Simpson, 1928, Catal. Mesozoic Mammalia in Geol. Dept. B.M., where the mammal-remains 

are fully described and compared with those from the German Rhaetic.

RH7ETIC BEDS 

are present, and the top bed of the White Lias can be 

recognized, overlain by the Lower Lias limestones. 

Hereabouts and over a great part of Somerset and 

the adjoining counties the top bed of the White Lias 

is a white, fine-grained limestone, having a curiously 

marked upper surface resembling dried mud cracked 

by the sun. On account of this feature it early received 

the name SUN BED, but the origin of the cracks 

is by no means certainly known. The wide distribution 

of the bed introduces serious difficulties in the 

g way of accepting the popular explanation. The pre- 

00 sence in it of worm-tubes and the wings of insects, 

° however, shows that it was certainly formed in very 

o* shallow water. 

u 

J 

/ IV. THE SEVERN VALLEY NORTH OF BRISTOL 

When we pass out of the northern fringe of the 

Mendip Archipelago we see no more of the conglomeratic 

and beach deposits of Rhaetic age, so well 

shown on the flanks of the southern islands. During 

the construction of the South-Wales-Direct railway, 

the cuttings between Chipping Sodbury and Stoke 

Gifford exposed Rhaetic Beds lapping on to the Carboniferous 

rocks of Kingswood Island; but there were 

no conglomerates (fig. 18). The normal shaly facies 

of the Rhaetic was seen contour-bedded over the 

hummocky surface of the Carboniferous Limestone, 

forming 'bedding-anticlines'. The thickness varied 

considerably according to the contours of the bottom, 

and at the base was an intensely hard, but impersistent, 

Bone Bed. In the railway-cutting at Lilliput 

the Bone Bed was seen resting on the Old Red Sandstone 

and was packed with vertebrate remains. Considerable 

lateral variation in the beds was also apparent, 

lenticular hard bands, sometimes gritty, but generally 

^ of limestone, appearing at various levels in the Con- 

£ torta Shales. 1 

g On the whole, over the region between Bristol 

^ and Tewkesbury the Rhaetic succession shows re- 

° markable correspondence in all the exposures. It is 

2 thinnest at Redland, Bristol, close to the shore of the 

u ' ' 

| 1 O 

S. H. Reynolds and A. Vaughan, 1904, Q.J.G.S., vol. lx, 

pp. 194-8. 

FIG. 18. Section in the railway-cutting between Chipping Sodbury 

Station and Lilliput Bridge, Glos., showing the Rhaetic 

Beds, without littoral facies, contour-bedded over Carboniferous 

Limestone and Old Red Sandstone. From S. H. Reynolds and 

A. Vaughan, 1904, Quart. Journ. Geol. Soc., vol. lx, p. 198, fig. 2. 

(Horizontal scale: 1 inch = 300 ft.; vertical scale: 1 inch = 75 ft.)

RH/ETIC : SEVERN VALLEY 107 

Clifton Island, where it measures only 13 ft. in thickness, although maintaining 

its normal characters. The more usual thickness is from 20 ft. to 25 ft., 

increasing to 30 ft. towards Tewkesbury. 

The region is classic ground in the history of Rhaetic geology. The most 

important sections are Aust Cliff and Sedbury Cliff on the left and right banks 

of the Severn opposite Chepstow; Goldcliff, in the Rhaetic and Lias patch east 

of the mouth of the Usk, opposite Newport; the Stoke Gifford and Chipping 

Sodbury railway-cuttings, already mentioned, the former 5 miles north of the 

centre of Bristol; and a road-cutting at Redland, Bristol. Farther north are 

the fine cliff-sections on the banks of the Severn: Wainlode Cliff on the left 

bank between Gloucester and Tewkesbury, and a neighbouring road-cutting 

known as Coomb Hill, and Garden Cliff, Westbury on Severn, on the right 

bank 8 miles west-south-west of Gloucester (Plate II). 

These sections may be summarized in the following sequence: 

SUMMARY OF THE RH^TIC BEDS OF THE SEVERN VALLEY 1 

Langport Beds or White Lias, 0-1 \ ft.: 

The White Lias is extremely attenuated and disappears altogether north of 

Bristol, not to reappear before Stratford on Avon is reached. At Redland, 

Bristol, and in various exposures around Bath, it consists only of the Sun Bed, 

the usual 1 ft.—ft. band of hard, white or cream-coloured, fine-grained 

limestone, having a conchoidal fracture, and its upper surface marked with 

cracks. It contains Ostrea liassica, Modiola Iangportensis, insect wings and 

worm-tubes. 

Cotham Beds. 

The COTHAM or 'LANDSCAPE' MARBLE (from Cotham near Bristol) is best 

developed in Gloucester and Somerset. It is a peculiar white stone up to 

8 in. in thickness, with arborescent markings which are supposed to have been 

caused by the escape of contained gases generated by decomposition in the 

mud. In the northern sections, at Wainlode and Garden Cliffs, it passes into 

a few inches of limestone crowded with the miniature Pseudomonotis fallax 

and noted for its insect fauna. The insect remains consist chiefly of elytra of 

beetles, but there are some wings allied to a Neuropteron, Chauliodes. They 

are associated with leaves of a fern, Otopteris obtusa, and small fragments of 

carbonized wood, with marine shells. At Sedbury Cliff the bed was removed 

by erosion at the beginning of Liassic times, the base of the Lower Lias being 

composed of a conglomerate of Cotham Marble fragments. 

Below the Cotham Marble is a band of clay, varying in thickness but always 

identifiable, separating it from an Estheria and Naiadites limestone below. 

Estheria minuta var. brodieana and the plant Naiadites lanceolata, sometimes 

associated with Pleurophorus and ' Schizodus' ewaldiy form a widespread and 

constant horizon in this area, usually in a bed of limestone. In the southern 

sections, around Bristol, the fossils occur in the top of from 2 ft. to 4 ft. of 

limestones, either massive or fissile; the lower parts are barren. In the 

1 See A. R. Short, 1904, Q.J.G.S., vol. lx, pp. 170-93 ; L. Richardson, 1903, ibid., vol. lix, 

pp. 390-5; 1905, ibid., vol. Ixi, pp. 374-84; 1903, Proc. Cots. N.F.C., vol. xiv, pp. 127-74, 

251-7.


northern sections (Sedbury, Wainlode, Westbury, &c., and at Goldcliff) the 

lower parts become argillaceous, Estheria and Naiadites occurring in a thin 

limestone or nodule-bed overlying barren shales. The transition is seen 

at Aust Cliff, where the Estheria Bed overlies yellow, thinly-bedded, very 

argillaceous limestone, often crumbly. Naiadites is of special interest because 

it is probably the earliest known fossil plant belonging to the Lycopodiaceae. 1 

Westbury Beds or Contorta Shales. 

This division is thinnest (6 ft. 10 in.) at Redland, Bristol, near the Clifton 

Island, and thickest in the north, at Westbury on Severn (19 ft. 8 in.). The 

mass of the shales may be divided into two palaeontological subzones, corresponding 

to the local acmes of Chi. valoniensis (above) and of Pt. contorta 

(below), with a vertebrate zone at the base. The top is often formed by a 

Pecten-bed limestone, and there is sometimes a lower Pecten-bzd as much as 

8 ft. lower (e.g. at Aust Cliff). Shales with Chlamys may occur above the upper 

Pecten-bed (e.g. at Sedbury Cliff and the northern sections). Mollusca are 

abundant in this upper part, as in Somerset and Dorset, and they belong to 

the same species. At Deerhurst Richardson found a specimen of Heterastrceay 

the only compound coral recorded from the British Contorta Beds. 2 At Wainlode 

and Westbury a few thin seams of sandstone occur in the shales, as at 

Langport. 

The Bone Bed, with the usual vertebrates, which are often extraordinarily 

abundant, is impersistent; it usually takes the form of a sandstone, resting on 

a markedly eroded surface of the underlying Tea Green Marls, or (at Chipping 

Sodbury) Carboniferous Limestone. At Wainlode and Westbury, in the north, 

however, 2 ft. of black shales come in between the Bone Bed and the eroded 

surface, as at Watchet, in Somerset. This irregular distribution of the beds 

below the Bone Bed is explained by Richardson as due to the Tea Green Marls 

having been gently folded towards the end of Keuper times, with the result 

that sedimentation was first renewed in the hollows, each successive bed 

having an increasingly wide extent (see fig. 14). 

The occurrence of thin seams of sandstone in the lower part of the Westbury 

Beds at Westbury and Wainlode may perhaps be attributed to proximity 

to the Palaeozoic rocks of the Welsh Border, where the coast-line presumably 

lay. The tendency to a sandy facies becomes considerably more marked 

farther north, towards the Malverns. An outlier on Berrow Hill, 7 miles west 

of Tewkesbury, which lies only 2 miles from the present outcrop of the 

Malvern Palaeozoic rocks, was especially excavated by Richardson in the hope 

of finding signs of a littoral facies of the Rhaetics. Five thin seams of sandstone 

and sandy limestone were found interbedded with the Contorta Shales (the 

total thickness of which was reduced to about 9 ft.) and they were found to 

rest on a lower horizon in the Tea Green Marls. 3 

Similar sections of the Westbury Beds have been recorded by Richardson 

near the extremity of the long tongue of Lower Lias and Rhaetic Beds that 

extends north of the general outcrop towards Worcester and Droitwich. At 

Crowle, 4 miles east-north-east of Worcester, and in a railway-cutting at 

1 I. B. J. Sollas, 1901, Q.J.G.S., vol. lvii, p. 311. 

2 R. F. Tomes, 1903, Q.J.G.S., vol. lix, pp. 403-7. 

3 L. Richardson, 1905, Q.J.G.S., vol. lxi, pp. 425-30.

RH/ETIC: MIDLANDS 109 

Dunhampstead near Droitwich, the lowest 8 ft. of the Rhaetic consists largely 

of numerous thin sandstone layers interbedded with shales. The Bone Bed 

is represented by a 1 ft. sandstone layer 4 ft. from the base, containing fish 

teeth and scales and vertebrae, while two other sandstone layers contain 

'Schizodus' casts, and many show ripple-marks and tracks of annelid worms. 

The junction with the Tea Green Marls, which are well exposed below, is 

abrupt and non-sequential. 1 

V. FROM THE SEVERN TO THE HUMBER 

From the Severn Valley the outcrop of the Rhaetic Beds turns north-eastward 

across the Midland Plain of England, passing through the counties 

of Worcester, Warwick, Leicester, Nottingham, and Lincoln. Between the 

Severn and the Stratford Avon long tongues stretch northward, usually overlain 

by Lower Lias, to Droitwich and Wootton Wawen, near Henley in Arden, 

while the farthest outlier is as distant as Knowle, midway between Birmingham 

and Warwick. The outcrop sometimes forms a recognizable surface-feature, 

though for long distances its position can only be inferred where the limestones 

at the base of the Lower Lias form a subdued escarpment overlooking the 

Triassic plain, and the Rhaetic Beds crop out along it or at its foot. Exposures 

are few and far between, but enough have been seen from time to time to 

prove that the Rhaetic formation maintains its essential characteristics all 

across England. 

The most interesting feature of the Midland area is the return of the true 

White Lias or Langport Beds, which, after being absent from the greater part 

of Gloucestershire, reappear near Stratford on Avon and continue nearly to 

Wigston in Leicestershire, where they disappear for good. The Cotham Beds 

and the Westbury Beds or Contorta Shales continue unchanged, while the 

junction of the latter with the Tea Green Marls remains, as usual, abrupt and 

non-sequential. 

Apart from the exposures mentioned at the end of the last section, on the 

west side of the Tewkesbury-Droitwich tongue, adjoining the Severn Valley, 

few others of interest have been recorded in the area where the Langport 

Beds are absent, west of the Stratford on Avon district. Perhaps the best was 

described by Richardson in the bank of a sunk bridle-path at Woodnorton, 

near Evesham, and this was said to be the only section in Worcestershire 

showing the upper beds. Beneath the Ostrea Beds of the Lower Lias were 

19\ ft. of grey, greenish and yellow shales, with the thin Estheria Bed of the 

Cotham Marble Series only 8 ft. from the top, containing Estheria minuta 

var. brodieana and Naiadites lanceolata. These rested on normal dark shales 

belonging to the Westbury Beds, with the usual fossils, but the full thickness 

could not be seen. 2 About Binton, Grafton, Wilmcote, and Bickmarsh, only 

a short distance west of Stratford on Avon, the White Lias is still absent, and 

over this area the Lower Lias has at its base a peculiar hard, shelly limestone 

called the Guinea Bed, which is frequently conglomeratic. It is no longer 

exposed, but old records show that it contains a typical Lower Lias assemblage 

of shells, mixed with others apparently derived from the Rhaetic. It may be 

1 L. Richardson, 1903, Geol. Mag. [4], vol. x, p. 80. 

2 L. Richardson, 1903, loc. cit., p. 82.


significant that this area lies across the continuation of the Sedgley-Lickey 

Axis. 

The White Lias first appears as field rubble about half a mile south-east 

of Sweet Knowle, south of Stratford on Avon, and is to be seen in some abandoned 

workings on Wimpstone Field and again at Newbold Limeworks, all 

about on the line of the Vale of Moreton Axis. 

'Thence, right through to Rugby', according to Richardson, St is well and persistently 

developed (maximum about 10 ft.), of very much the same appearance as 

the Somerset White Lias, contains specimens of Dimyodon intus-striatus (Emmr.) 

abundantly in places, and not infrequently corals. Certain of its beds are well bored 

by annelids, and at Church Lawford portions are pebbly; while in the same neighbourhood 

it has a ferruginous deposit on top, with which are associated ample 

indications of erosion by water: in other words there is abundant evidence for a nonsequence 

between the White Lias and the superincumbent Lower Lias deposits.' 1 

Church Lawford and Rugby, as has been noted, lie upon the prolongation 

of the Nuneaton Axis. 

The Cotham Beds, consisting of the usual pale greenish-grey marls, continue 

with little change throughout Warwickshire and the adjacent counties 

farther north and east. The Estheria Bed has been proved at W T ilmcote, 

Wootton Wawen, Summer Hill railway-cutting between Stratford on Avon 

and Alcester, and at other places, but no 'landscape marble' has been found. 

The Westbury Beds or Contorta Shales are also normal and persistent, 

though their full thickness cannot be measured until Leicester is reached. The 

junction between them and the Cotham Beds is a gradual transition, but their 

lower limit is abrupt. Judging from old records and from specimens that have 

been obtained from Summer Hill, fossils abound at certain horizons, the 

commonest being Pteria contorta and 'Schizodus' sp. Hard beds do not figure 

prominently, but there are a number of thin sandstone layers in the lower 

part of the shales in the Summer Hill railway-cutting, and Brodie obtained 

highly fossiliferous PectenAimzstone from temporary excavations at Brown's 

Wood, miles west of Bearley Junction. The Bone Bed is poorly developed, 

being nowhere very rich in vertebrate remains. 2 

The finest section of the Rhaetic Beds in the Midlands is at Glen Parva 

Brickworks, near South Wigston, 4 miles south of Leicester. The total thickness 

is 40 ft.—Cotham Beds io| ft., Westbury Beds 20 ft. 9 in. 3 In the old 

Spinney Hill sections on the eastern outskirts of Leicester, minutely described 

by W. J. Harrison, 4 but now overgrown, there was another section of Westbury 

Beds visible to a thickness of 10 ft., with an Estheria Bed at the top. 5 The 

Westbury Beds in these exposures have proved rich in the usual fossils, and 

in addition a starfish, Ophiolepis damesii, was said by Harrison to occur in 

large numbers in a certain seam among the dark, finely-laminated shales. A 

noticeable feature is the almost entire absence of hard bands. At the base a 

conglomeratic Bone Bed in-2 in. thick), consisting of a pyritous impure 

1 L. Richardson, 1912, Geol. Mag. [5], vol. ix, pp. 24-33, for Warwickshire. 

- Ibid., p. 26. 

1 Measurements and grouping according to the latest revision by L. Richardson, 1909, Geol. 

Mag. [5], vol. vi, pp. 366-70. 

4 W. J. Harrison, 1876, Q.J.G.S., vol. xxxii, pp. 212-18. 

5 There are unconfirmed records of Estheria minuta at two levels in the Contorta Shales of 

the Glen Parva Brick Pit.

RH/ETIC: MIDLANDS 109 

sandstone, is full of pebbles of Triassic sandstone, slaty and quartzose rocks 

from Charnwood Forest, phosphatic nodules, coprolites, and fragmentary 

remains of saurians and fish. From this have been obtained bones or teeth or 

scales of Ichthyosaurus, Plesiosaurus, Saurichthys acuminatus, Acrodus minimus, 

Sargodon tomicus, Hybodus cloacinus, Nemacanthus monilifer. 

Similar sections have been described at various points along the outcrop 

farther north, but nearly all were railway-cuttings which have become overgrown, 

or old clay pits which have fallen into disuse and are now obscure. 

In a railway-cutting at Stanton on the Wolds, 1 between Nottingham and Melton 

Mowbray, a few reptilian bones occurred at the base of the Contorta 

Shales, but the main Bone Bed, yielding all the vertebrate species found at 

Leicester, with coprolites and quartz pebbles, appeared 2 ft. 8 in. higher up, 

in the form of a i-in. seam of soft white sand. At Barnston, in a cutting on the 

line south-east of Bingham, also on the border of the Vale of Belvoir, the Bone 

Red was hard and pyritic once more, as at Leicester, but its position was still 

ft. from the base. In neighbouring railway-cuttings at Cotham and Kilvington, 

a few miles south of Newark, 2 the whole Rhaetic formation was cut 

through, but, although 34 ft. thick, it proved exceptionally unfossiliferous. 

The nodular Estheria Bed was present near the top, but all sign of the Bone 

Bed was lacking, both here and at Newark. 

In the Lincoln district the outcrop is much concealed by superficial deposits, 

but the Rhaetic Beds were exposed during the making of cuttings for the Great 

Northern line between Gainsborough and the adjoining village of Lea. 3 

Here there was not only one bone bed, but three, as in parts of the West 

Country: one was at the base, consisting of 1 ft. of loose micaceous sandstone, 

and the other two were 8 ft. and 8 ft. 5 in. higher, comprising mere seams of 

coprolites, worn bones, fin-spines, teeth, fish-scales and small pebbles. A 

vertebrate fauna even richer than that at Leicester was found, and ChL 

valoniensis abounded again near the top. In all 26 ft. of black shales were 

exposed, with occasional thin sandstone seams, and Pteria contorta and 

'Schizodus' ewaldi were abundant throughout, showing that the whole series 

belonged to the Westbury Beds. At other places in Lincolnshire the Upper 

Rhaetic has been occasionally seen, and at the top a typical Sun Bed has been 

observed, covered with cracks, as in Somerset. 

In all these Midland exposures, wherever the base of the Rhaetic has come 

under observation, it rests upon a markedly eroded surface of the underlying 

Tea Green Marls, which in turn pass down without any visible break into the 

typical red marls of the Keuper. 4 

VI. THE MARKET WEIGHTON AXIS 

Much detailed work still remains to be done before it can be ascertained 

what changes the Rhaetic Beds undergo as they cross the Market Weighton 

1 E. Wilson, 1882, Q.J.G.S., vol. xxxviii, p. 454. 

2 Ibid., pp. 453-4. (This Cotham is not to be confused with the one near Bristol.) 

3 M. F. Burton, 1867, Q.J.G.S., vol. xxiii, pp. 315-22; and W. A. E. Ussher, 1888,'Geol. 

Lincoln', Mem. Geol. Surv., p. 12. 

4 There seems every probability that the Tea Green Marls were once also red and noncalcareous, 

but that in course of time they have been bleached and rendered partly calcareous 

owing to the downward infiltration of carbonate of lime and some deoxidizing chemical agent, 

possibly derived from the decomposition of the organic remains in the overlying Rhaetics.


Axis. Fox-Strangways 1 followed the outcrop across the critical belt and 

obtained a number of indications of green and black shales with here and there 

thin bands of sandstone, of Rhaetic aspect, at North Cliff, Market Weighton, 

Londesborough Park, Warter Priory, and Pocklington. There can thus be no 

doubt that the outcrop is continuous. A well at Market Weighton 14 ft. deep 

was said to be principally in black Rhaetic shale with minute shells, while a 

road-cutting at North Cliff showed 18 ft. or more of shale with sandy bands 

below the Pteromya crowcombeia Bed at the base of the Lower Lias. Here 

there is no indication of White Lias, but north of Market Weighton, at Warter 

Priory near Pocklington, field rubble of White Lias was said to be abundant, 

and it is a feature of the top of the Rhaetics of the Yorkshire Basin. It probably 

represents the Cotham Beds rather than the true White Lias or Langport 

Beds. 2 

VII. THE YORKSHIRE BASIN 

Rhaetic Beds are not exposed on the coast of Yorkshire, for the outcrop is 

covered by the alluvium of the River Tees, but they have been met with at 

numerous inland localities. The best sections are at Northallerton, where the 

Rhaetic is 27 ft. thick. The sequence, which may be considered typical of 

Yorkshire by reason of its central position, is as follows: 3 

Cotham Beds (? and Langport Beds): 10 ft. of white shale, with a 3-in. 

band of white argillaceous limestone at the top (? Sun Bed) have been assigned, 

on the ground of lithological resemblance, to the W r hite Lias sensu lato. No 

fossils have been found, but it is probable that only the Cotham Beds are 

represented. 

Westbury Beds or Contorta Shales, 17 ft. The Contorta Shales consist 

mainly of black, crisp shales, with Pt. contorta throughout. They are interrupted 

by two hard bands of light-coloured, close-grained, siliceous rock full 

of 'Schizodus' ewaldi. The upper band (about the centre) is 3 in. thick and 

yields also fragmentary crinoid stems. The lower band ft. from the base) 

is 6 in. thick, and in the shale immediately above it occur numerous fish-scales. 

This is thought to represent the Bone Bed. 

Unfossiliferous Tea Green Marls appear below. 

VIII. NORTHERN IRELAND: THE ANTRIM PLATEAU 

Outliers of Lower Lias, which will be described in the following chapter, 

exist far from the main outcrop in the Shropshire and Cheshire Plain and also 

in the Plain of Carlisle. Their stratigraphy is imperfectly known owing to 

coverings of Drift, and although it is likely that Rhaetic Beds exist beneath 

the Lias, as yet no definite evidence of their presence has been obtained. 

About 120 miles due west of the Carlisle outlier further proof of the extension 

of the Liassic sea is found in Antrim, especially near Belfast, and here 

thick beds of fossiliferous Rhaetics are exposed beneath. The deposits owe 

their preservation directly to the protective covering of the Tertiary basalt 

plateau, beneath which they probably have a considerable extension, since 

they crop out at many favourable points around the edge. 

1 C. Fox-Strangways, 1886, 'Geol. Country between York and Hull', Mem. Geol. Surv., 

p. 10. 

2 L. Richardson, in lit. 

3 C. Fox-Strangways, 1886, 'Geol. Northallerton and Thirsk', Mem. Geol. Surv., p. 13.

RHIETIC: N O R T H E R N I R E L A N D 113 

The beds were described by Tate in 1864, 1 in the days when all the strata 

above the Contorta Shales were classed together as White Lias. A detailed 

interpretation of Tate's records is difficult to make. 

The best section was at Collin Glen, near Belfast, where the total thickness 

of beds assigned to the Rhaetic was about 46 ft., but it is considerably faulted 

and now much obscured. At the top, underlying Ostrea liassica Beds forming 

the base of the Lower Lias, were described 16 ft. of grey and reddish marls, 

resting on 10 ft. of arenaceous shales. Both of these divisions contained 

Protocardia rhcetica, and so can be classed at least as 'Upper Rhaetic'. Beneath 

are the Contorta Shales, typically developed and 20 ft. thick. They consist of 

black shales with thin bands of blue argillaceous limestone and in the lower 

part seams of compact sandstone, with a 2-in. Fish Bed or Bone Bed 6 ft. 7 in. 

from the bottom. Tate recorded Pt. contorta, Chi. valoniensis, Protocardia 

rhcetica and Cardium cloacinum throughout. A rich collection of fish-remains 

has been made from the Bone Bed, which has been likened to that in the 

West of England. 2 

At Cave Hill, 3 miles north of Belfast, the Upper Rhaetic is only about 

14 ft. thick. At Larne it contains pseudo-oolitic and pisolitic concretions 

disseminated through the grey marls. The Contorta Shales are still over 19 ft. 

thick at Whitehead railway-cutting, 14 miles north of Belfast, but only 16 ft. 

thick at Cave Hill. 

Tate remarked on the abrupt change from the red and grey marls of the 

Keuper to the black Contorta Shales in Ireland. Nowhere is there any sign 

of gradation from one to the other. 

IX. T H E H E B R I D E A N A R E A 

South of Alt na Teangaidh, near Gribun, in Western Mull, about 30-40 ft. 

of Rhaetic Beds follow conformably on the Triassic sandstone. They consist 

principally of dark sandy limestone or calcareous sandstone with somewhat 

wavy bedding, and subordinate yellow sandstone. The junction with the Lias 

is nowhere seen. Lamellibranchs are common and are the only fossils, excepting 

some fish-scales; the following species have been recorded: Pt. contorta, 

Gervillia precursor, Myophoria poster a (?) (Bronn), Chi. valoniensis, Protocardia 

rhcetica, Pleurophorus elongatus and Modiola (?) sp. These species 

occur throughout the section at Gribun and suggest that the whole belongs to 

the Westbury Beds. 

Later beds may be represented in the Wilderness, where Bailey described 

a little cliff showing 5 ft. of shales with cementstones, of rather doubtful relations, 

overlying 20 ft. of obviously Triassic sandstone with conglomerate 

(cornstone). 3 

In Morven, half a mile south of the Rannoch River, 10 ft. of fine-grained 

white sandstone, sometimes pebbly, with layers of ill-preserved lamellibranchs 

near the top, and underlain in one place by 6 in. of grey marl, are seen 

resting on the Triassic cornstone. The lamellibranchs, so far as they can be 

1 R.Tate, 1864, Q J.G.S., vol. xx, pp. 103-11. 

2 W. F. Hume, 1897, Q.J.G.S., vol. liii, p. 549. 

3 E. B. Bailey, 1925, Tre-Tert. Geol. Mull, Loch Aline and Oban', Mem. Geol. Surv., 

PP. 72-3. 

8.'>4:J71 I

FIG. 19. Sketch-map of the Inner Hebrides, showing 

the Jurassic outcrops (in black).

RHAETIC: HEBRIDES 115 

determined, suggest a Rhaetic age: Pteromya simplex Moore, P.crowcombeia( ?) 

Moore, Pleurophorus elongatus (?) Moore, and some others not identified 

specifically. Lower Lias limestone crops out 20 ft. higher up, but the intervening 

strata cannot be seen. 1 

The only other place in Scotland where a definite Rhaetic fauna has been 

found is the Isle of Arran. It was described here by Messrs. Peach, Gunn, and 

Newton, and lies in a mass of typical Rhaetic shale tumbled down the throat 

of a Tertiary volcano, but the beds no longer occur in situ, having been otherwise 

completely removed by erosion. The fossils procured from the volcano 

are identified as Pt. contorta, Chi. valoniensis,'Schizodus' [ezvaldi], Protocardia 

rhcetica (?), Modiola minima (?), Estheria minuta (?), and Gyrolepis alberti (?), 

a thoroughly conclusive assemblage. 2 

As the Isle of Arran is some 40 miles from the edge of the Antrim Plateau 

and 50 miles from Mull, this occurrence provides a valuable link between 

the Rhaetic areas of Ireland and the Hebrides, greatly facilitating palaeogeographical 

restorations. 

In Skye, near Sconser, Loch Sligachan, 9 ft. of green sandstone and blue 

sandy limestone with shale partings are seen below blue Lower Lias limestone, 

and are called by the Survey 'Passage Beds (= Rhaetic?)'. One band yields 

Chi. valoniensis and another is said to be full of a small Ostrea. A few feet of 

similar beds between the Trias and the Lower Lias limestones north-east of 

Heast, Skye, may also be of Rhaetic age, but the evidence is inconclusive, 

since they have yielded only a fish scale, Ostrea sp. and plant remains. 3 

On the other side of Skye, and in Raasay, at Applecross and elsewhere, there 

is no recognizable trace of Rhaetic Beds, the Lower Lias having apparently 

overlapped on to the older rocks. On the shores of Loch Slapin in southeast 

Skye, strata as high as the semicostatum zone can be clearly seen resting 

directly on Cambrian limestones. 

Commenting on the Hebridean Rhaetic sections in 1929, Richardson 

remarks: 4 

'The descriptions of the Rhaetic sandstone in Mull given by Lee and Bailey call to 

mind the Rhaetic sandstone of the Bridgend district of Glamorganshire; and the 

account by Bailey of "greenish-grey shale with cream-weathering cementstones", 

which appeared to him to succeed the sandstone, inclines one to suggest that the 

Cotham Beds are represented.' 

The localized distribution of the Scottish Rhaetic Beds and their tendency 

to be overlapped or overstepped by the Lower Lias are both unusual features. 

X. EASTERN SCOTLAND 

On the coast of Sutherlandshire, at the south end of the narrow coastal 

strip of Jurassic rocks (of which a great deal more will be said in ensuing 

chapters), the base of the Lias crops out in the foreshore below the pier of 

Dunrobin Castle, Golspie. The exposure is a poor one, only visible at low 

1 G. W. Lee, 1925,'Pre-Tert. Geol. Mull, Loch Aline and Oban\ Mem. Geol. Surv., pp. 73-4. 

2 1901, Q.J.G.S., vol. lvii, pp. 226^43. 

3 H. B. Woodward, 1910, 'Geol. Glenelg, Lochalsh and S.-E. Skye', Mem. Geol. Surv., 

PP. 94-7. 

4 1929, Handb. Geol. Great Britain, p. 348.

116 RHAETIC BEDS 

tide, but it shows about 6 feet of unfossiliferous grits and conglomerates at the 

base of the Lias, resting upon Triassic cherty rock similar to some at Elgin, 

on the other side of the Firth. The conglomerate contains pebbles of chert, 

sandstone, and limestone derived from the Trias, and in masses of similar 

conglomerate found in the Boulder Clay on the south side of the Moray Firth 

have been found fossils similar to those in the Rhaetic of Scania. 

Although there is no definite evidence, the Dunrobin conglomerate is 

therefore generally supposed to be of Rhaetic age. 1 

XI. KENT 

In the Kent borings no Rhaetic fossils were encountered. 

1 G. W. Lee, 1925, 'Geol. Golspie', Mem. Geol. Surv., p. 68.

Stages. 

CHAPTER V 

LOWER LIAS 1 

Zones (Faunizones). , | Stratigraphical Divisions in 

(Plates XXX, XXXI). 

Dorset. 

£ £ z 1 

Prodactylioceras davcei2 GOWK 

< < Tragophylloceras ibex 

WEAR CLIFF Or 

GREEN AMMONITE BEDS 3O-IO5 ft. 

Belemnite Stone 

STONEBARROW BEDS or 

Uptonia jamesoni BELEMNITE MARLS 75 ft. 

Echioceras raricostatum 

z < 

2 

3 Hummocky Limestone 

z < 

2 

D 

s 

w 

Z 

Oxynoticeras 

Asteroceras 

Arnioceras 

oxynotum 

obtusum 

semicostatum 

BLACK VEN MARLS 14O-5O ft. 

Birchi Tabular, Birchi Nodular 

4 D 

s 

w 

Z 

SHALES WITH BEEF 70 ft. 

Coroniceras bucklandi Table Ledge 

Scamnoceras angulatum 

1 

5 | LYME REGIS BEDS Or 

0 

BLUE LIAS LIMESTONES 85 ft. 

Psiloceras planorbis 

£ 

< 

H Ostrea liassica | 

H 

w 

X Pleuromya tatei j 

PRE-PLANORBIS BEDS IZ ft. 

ALMOST the entire succession of the Lower Lias in its typical develop- 

-/Xment across England from the Dorset coast consists of clays and shales, 

in the lower parts of which numerous bands of calcareous mudstone or claylimestone 

have been formed by secondary chemical processes. 

A rich and varied succession of ammonite faunas is preserved, and the lower 

zones are especially characterized by beds of Ostrea, Gryphcea and some 

other lamellibrachs; apart from the ammonites and Gryphaeas, however, the 

molluscan fauna is relatively poor. The most conspicuous remains are the 

skeletons of the great marine reptiles. The presence of these, and also of fossil 

insects, points to deposition, not in deep water as frequently deduced from the 

clayey sediment, but in a comparatively shallow continental sea. The rivers 

flowing into the Liassic sea had reached maturity, for instead of bringing down 

detrital material from the surrounding land, they carried only fine mud. 

Mixed with the mud in suspension came a high proportion of iron, which, in 

the form of minutely disseminated pyrites, gives the usual dark grey to black 

colour to the Lias shales. 

1 For the origin of the word Lias see footnote 3 on p. 12. 

2 Called by Wright the capricornu zone (1863) and the henleyi zone (1878), but Dr. Lang 

sees no good reason for altering Oppel's name. The genus Prodactylioceras was proposed for 

Coeloceras davcei auct. by Dr. Spath, 1923, Geol. Mag., vol. lx, p. 10. 

3 This includes the old armatum zone, which was above the raricostatum horizon in Yorkshire 

but was proved by Dr. Lang to occur below it in Dorset, and therefore to have no value. 

For full discussion see Spath, 1925, Naturalist, pp. 167-72. 

4 Oppel's Pentacrinus tuberculatus zone and approximately Wright's turneri zone; renamed 

the semicostatum zone by Judd and adopted as such by the Survey and subsequent writers. 

5 Formerly Schlotheimia angulata; for generic revision see Spath, 1925, Naturalist, 

pp. 201-6. Included in the bucklandi zone by Wright (i860 and 1863).

120 

THE LIAS 

I. T H E D O R S E T - W E S T S O M E R S E T AREA 

(a) The Dorset Coast 

The Lias is cut by the Dorset coast in such a way that a complete section is 

laid bare across the extension of the trough of deposition that stretched from 

the Mendip Hills and South Wales in the north to the massif of the Cotentin 

and Normandy in the south. One after another its zones rise from the beach 

to build the line of magnificent cliffs extending from Bridport in Dorset 

westward past Charmouth and Lyme Regis to Seaton in Devon. 

From the early days of geology attention has been drawn to the Lower Lias 

of these cliffs by the profusion of ammonities and by the discoveries of giant 

reptile skeletons made from time to time near Lyme Regis. A great deal of 

new light has been thrown on the succession by the careful studies and collecting 

of Dr. W. D. Lang, from whose papers the following account is principally 

derived. The remarkable sequence of ammonite epiboles established by him 

has been shown in Table V, p. 28, where some general remarks on the subject 

have already been made. 

SUMMARY OF THE SUCCESSION ON THE DORSET COAST 1 

(Total thickness 430 ft.) 

Davcei Zone (WEAR CLIFF OR GREEN AMMONITE BEDS), 100 ft. 

This occupies a longer stretch of cliff than any other division of the Lower 

Lias on the Dorset coast. Faulted up from beneath the beach at Seat own, it 

forms the lowest precipice of Golden Cap, and then rises gradually westward 

to the highest precipice of Stonebarrow Cliff, thinning out beneath the Upper 

Greensand. Its upper limit is clearly defined by the prominent basal bed of 

the Middle Lias, called the Three Tiers, its lower limit by a hard band, the 

Belemnite Stone (Plates III and V). 

The series consists of marly clays with ferruginous bands, somewhat sandy 

towards the top. It derives its name from the occurrence of the ammonite 

Androgynoceras latcecosta embedded in limestone nodules, with the gaschambers 

filled with green calc-spar. Specimens used to be cut longitudinally, 

polished, and sold as ornaments. 

The monotony of the clays is broken by three more or less continuous 

limestone bands, which mark off four approximately equal divisions, each 

from 20 ft. to 30 ft. thick under Golden Cap. The most conspicuous and 

constant is the central limestone, known as the Red Band. W T hen fresh it is 

hard and firm, but being only 6 in. to 1 ft. thick, it has generally been weathered 

nearly to the core, so that it is crumbly and brown with a pinkish-red surface. 

The commonest fossils are species of Liparoceras, but Tragophylloceras 

loscombi and the zone fossil, Prodactylioceras davoeiy also occur. T. loscombi 

ranges through the whole of the Green Ammonite Beds and passes up into 

the Middle Lias. 

The other two limestone beds are of very different appearance from the 

Red Band, being hard, nodular and impersistent, while fossils are rarer (as 

1 W. D. Lang, 1913-28; for list of papers, see the Bibliography, at end. For a general 

account, giving the stratal succession, see H. B. Woodward, 1911, 'Geol. Sidmouth and Lyme 

Regis', 2nd ed., Mem. Geol. Surv., pp. 21-40.

they are also in the intervening clays). 

Dr. Lang has determined, however, 

that ammonites of the genus Oistoceras 

characterize the upper limestone band 

and the lower part of the clays above 

it, while Androgynoceras latcecosta is 

found in and about the lower limestone 

band. 

The Green Ammonite Beds thin out 

considerably from east to west. Only 

the lower division, below the Red Band, 

is fully exposed west of Golden Cap, 

but in two miles this dwindles from 

48 ft. one mile west of Golden Cap to 

14 ft. at S.tonebarrow. If the upper 

division thinned at the same rate before 

the Cretaceous denudation, the total 

thickness of the Green Ammonite Beds 

on Black Ven was only 30 ft. 

Ibex and Jamesoni Zones (STONE- 

BARROW BEDS OR BELEMNITE MARLS), 

75 ft- 

Underneath the Green Ammonite 

Beds, rising westward along the face 

of Stonebarrow Cliff, is a series of pale 

marly clays known as the Belemnite 

Marls, which build the third or upper 

precipice of Black Ven, between Charmouth 

and Lyme Regis. Almost the 

only abundant and well-preserved 

fossils are belemnites. 

The top is marked by the BELEMNITE 

STONE, a 6-inch band of nodular but 

persistent limestone, which weathers 

creamy white. It is full of fossils, the 

belemnites being Passaloteuthis apicicurvata 

Lang, Hastites spadix-ari Lang, 

H. microstylus, and H. stonebarrowensis 

Lang, and the ammonites indicating 

the hemera of Beaniceras centaurus. In 

addition Lytoceras fimbriatum (Sow.) 

occurs, together with species of Tragophylloceras, 

and numerous lamellibranchs, 

gastropods and brachiopods. 

FIG. 20. Section along the cliffs from Pinhay 

Bay past Lyme Regis and Charmouth to near 

Seatown. Total distance 6 miles. After H. B. 

Woodward, 'Jurassic Rocks of Britain', vol. iii, 

J 893> P- 53, Mem. Geol. Surv, 

L O W E R LIAS: D O R S E T C O A S T 119 

o H 2: 

>o 

^ ui 

^ u_ 

3 - 

I : u 

U 

S- QJ 

> 

< 

Ou GO 

{J .> 

I flz

120 THE LIAS 

The rich belemnite fauna of the underlying marls, described by Dr. Lang, 

includes 5 genera and 26 species. The genus Passaloteuthis ranges through the 

whole series; Angeloteuthis and Hostites are confined to the uppermost 20 ft.; 

Clastoteuthis has a restricted range about the middle; Pseudohastites is confined 

to the lower half. A varied ammonite sequence has also been made out, 

as shown on p. 28. 

Raricostatum, Oxynotum and Obtusum Zones (BLACK VEN MARLS), 140- 

50 ft. 

At the base of the Belemnite Marls is a band of nodular limestone with 

Epideroceras exharedatum, called the Hummocky Limestone, which rises 

from the beach under Westhay Cliff, the eastern end of Stonebarrow. Palaeontologically 

it marks the disappearance of the genus Crucilobiceras and may 

be taken as the topmost horizon of the Sinemurian. The limestone serves to 

define the upward limit of a thick series of much darker clays and marls, 

called the Black Ven Marls from their building the main and middle precipice 

of Black Ven and the cliffs on either side of Charmouth. 

The uniformity of the series is broken by several layers of nodules and 

lenticular limestone bands, often enclosing ammonites. The nodules have a 

flattened ellipsoidal shape, suggestive of a secondary origin, and many are 

septarian. 

The most fossiliferous horizon is a lenticular limestone 14 ft. from the top, 

called the AMMONITE MARBLE. This is full of small ammonites of the genera 

Promicroceras, Echioceras, Euechiocerasy Pleurechiocerasy and Crucilobiceras, 

and it is on about the horizon of a similar limestone in North Dorset, which 

was formerly cut and polished under the name of Ammonite or Marston 

Marble. An interesting feature of this horizon is the abrupt reappearance of 

Gryphcea arcuata in abundance, well incurved and indistinguishable from 

forms in the Blue Lias, of which it is primarily characteristic. In the marls 

immediately above the Ammonite Marble is a Pentacrinite bed yielding 

Extracrinus briareus. 

About 48 ft. from the top is a layer of large nodules, up to 18 in. in diameter, 

enclosing specimens of Asteroceras stellare, while at 78-85 ft. down (about the 

middle) are three layers of 'flatstones', or large lenticular nodules, containing 

Asteroceras obtusum. The most conspicuous bands are twin layers at the base, 

1 ft. apart, enclosing large specimens of Microderoceras birchi: the upper layer 

is called the Birchi Tabular, and the lower, which is merely a row of large 

concretions, the Birchi Nodular. 

The lamellibranchs Lima giganteay Oxytoma iruequivalvis and Inoceramus 

faberi are fairly abundant throughout. 

Semicostatum Zone (SHALES WITH BEEF OR LOWER BLACK VEN BEDS), 70 ft. 

The lowest precipice of Black Ven Cliff, below the row of Birchi Nodules, is 

formed of 70 ft. of dark shales, paper-shales and marls, with occasional indurated 

bands of limestone and nodule-beds. They differ in appearance from 

the Black Ven Marls above by the presence of numerous interbedded seams 

of fibrous calcite with a superficial resemblance to beef. 

Palaeontologically the Shales with Beef may be divided, according to 

Dr. Lang, into three main divisions, an upper, corresponding with the range

PLATE III 

Photo. PurcK 

Black Ven (left), Stonebarrow Cliff (centre) and Golden Cap (right) from above 

the Cobb, Lyme Regis. 

Ph0t0 • Purch. 

Charmouth and Stonebarrow Cliff from the foot of Church Cliffs, Lyme Regis. 

The pale band is the Belemnite Marls; Black Ven Marls below, and Green 

Ammonite Beds above. The cliff is capped with Upper Greensand.

PLATE IV 


Frodingham Ironstone Workings, near Scunthorpe, Lines. 

Pleistocene sands are seen above the ironstone face. 


Blue Lias cliffs west of Lyme Regis. 

The cliff shows the characteristic banding produced by alternate beds 

of limestone and shale.

LOWER LIAS: DORSET COAST 121 

of Microderoceras and including the Birchi Beds; a middle division characterized 

by Arietites, Sulciferites, and Arnioceras, but no Agassiceras; and a 

lower division with both Arnioceras and Agassiceras. 

Bucklandi, Angulatum and Planorbis Zones (LYME REGIS BEDS OR BLUE 

LIAS LIMESTONES), 85 ft. 

At the foot of Black Ven Cliff, below the Shales with Beef, a 3 ft. 6 in. stone 

band rises from the beach, called the Table Ledge. This is the uppermost 

band of the Blue Lias, a thick series of blue-grey limestones separated by 

numerous shaly partings, which build the Church Cliffs to the east of Lyme 

Regis, where Monmouth drew up his army after landing in 1685, and the sea 

cliffs, rocks, and ledges westward to beyond Pinhay Bay (Plate IV). 

It is now generally considered that the series was originally deposited as a 

calcareous clay and that the formation of the limestones is a product of some 

process of rhythmic deposition of calcium carbonate, analogous with that 

depositing silica to produce bands of flint in the Chalk. The limestones here 

(in contrast with those near the Mendip Axis, around Radstock) seem to have 

been formed subsequently to any penecontemporaneous erosion that may 

have taken place. 

Palaeontologically, the most conspicuous features of the Blue Lias are an 

almost unbelievable multitude of large Coronicerates and other ammonites, 

with nests of Gryphcea arcuata, Lima gigantea and more rarely several other 

lamellibranchs. The geologist who walks from Lyme Cobb round the foot of 

the cliffs to Pinhay Bay beholds probably the greatest profusion of large 

ammonites to be seen anywhere in the British Isles. Some of the ledges are 

completely covered, so that one can hardly cross without stepping on ammonites, 

and fallen blocks may show several specimens over 2 ft. in diameter. 1 

The Crinoid, Isocrinus (Pentacrinus) tuberculatus (Miller), occurs at several 

horizons. 

The most famous products of Lyme Regis, the skeletons of the great marine 

reptiles and the Pterodactyls, were obtained principally from the Blue Lias. 

In particular, Ichthyosaurus communis and J. platyodon were found in the 

scipionianum epibole, near the top of the series. Many of the fishes, too, such 

as Acrodus, Eugnathusy Hybodusy Pholidophorus and Dapediusy came from the 

Blue Lias, although others, such as Chondrosteus and some species of Dapediusy 

are said to have been found in the obtusum zone in the Black Ven Marls. 

Interesting evidence of the southerly and westerly extension of the Lower 

Lias was the dredging up of Psiloceras planorbis or an allied species from the 

bottom of the sea below 80 metres of water, 30 miles south of the Eddystone 

Lighthouse. 2 

THE PRE-PLANORBIS BEDS, 12 FT. 

The basal beds of the Lower Lias continue to Culverhole Point, but they 

are much slipped and tumbled, and the most westerly good sections are to be 

seen in Pinhay Bay. Here the Prc-planorbis Beds consist of about 11 ft. of 

1 For a study of the ammonites of the Blue Lias see Spath, 1924, P.G.A., vol. xxxv, 

pp. 186-211. 

2 Kilian and Blanchet, 1923, C.R. Acad. Sci., Paris, vol. clxxvi, p. 156; quoted by Spath, 

1924, P.G.A., vol. xxxv, p. 190.

120 THE LIAS 

shelly limestone in twelve bands, separated by shale partings, with i ft. of 

dark paper shale at the base. 

Ostrea liassica Strickland is fairly abundant almost throughout, together 

with allied species of oysters, and more rarely, Lima gigantea and Modiola 

minima. In inland sections nearby, Pleuromya tatei has been found, a fossil 

that is highly characteristic in other parts of England. One bed near the base 

is locally crowded with Echinoderm spines, belonging to the species Cidaris 

edwardsi, Pseudodiadema lobata, Hemipedina bechei, and H. bowerbanki. 

(b) West Somerset 

Inland through Dorset and Somerset the Lower Lias outcrop forms broad 

tracts of valley country, flooring the Vale of Marshwood, the levels between 

Ilminster and Ilchester, the Glastonbury levels, and that larger portion of 

Sedgmoor lying north of the Polden Hills (King's Sedgmoor is formed by 

the Keuper Marls). Like the Rhaetic, the Lower Lias is overstepped and largely 

concealed by the Cretaceous rocks in the neighbourhood of Chard. 

Throughout this tract most of the quarries and cuttings expose only the 

Blue Lias limestones, which form a low ridge along the western margin of the 

outcrop, culminating in the line of the Polden Hills. The clays of the upper 

portion of the Lower Lias, dipping under the marshland and largely covered 

by alluvium, yield nothing of commercial value and never necessitate deep 

cuttings for railways. In consequence little is known of the development of all 

but the lowest two zones and the Prc-planorbis Beds. 

The limestones of the Lyme Regis district diminish rapidly northward, 

being largely represented by clays with only subordinate bands of stone in 

North Dorset and the Polden Hills. The most complete section was exposed 

in a railway-cutting across the inlier at Sparkford Hill, Queen Camel, Somerset, 

described by Charles Moore, and the lower parts of the section are 

duplicated and still accessible in neighbouring quarries at Camel Hill. 1 

Alternate bands of limestone and clay to the great thickness of 97 ft., with 

Psiloceras planorbis and Caloceras johnstoni, represent the planorbis zone, and 

Richardson has shown that here, as in the Dorset cliffs, the epibole of the 

ribbed C. johnstoni occurs above that of P. planorbis in the quarry. 2 Above 

this over 100 ft. of clay and marls, with some limestone bands, were formerly 

exposed in the cutting, and assigned to the angulatum and bucklandi zones. 

The Pre-planorbis Beds consist of about 11 ft. of shale and limestone bands, 

but Ostrea liassica and Modiola minima do not occur in the basal 4 ft., which 

instead yield remains of insects and the unique Crustacean, Coleia wilmcotensis 

(Woodward). As this locality lies directly over the North Devon Axis, 

it is evident that at least this part of the axis was quiescent during Rhaetic 

and early Liassic times. 

At Street, south of Glastonbury, 3 the lower part of the Blue Lias and the 

Pre-planorbis Beds have been quarried for many years for building-stone and 

paving-slabs, and have yielded quantities of Saurian remains. The quarries 

show about 20 ft. of blue limestone bands, alternating with shale, with 

1 L. Richardson, 1911, Q.J.G.S., vol. lxvii, pp. 45-9. 

2 Though in the cutting Moore recorded P. planorbis from the top bed. 

3 H. B. Woodward, 1893,7.^.0., PP- 79~8i.

LOWER LIAS: WEST SOMERSET 123 

Psiloceras planorbis in the highest 8 ft. Most of the Saurian remains have been 

obtained from the Pre-planorbis Beds, but they also occur in the topmost bed 

of the quarries. The Pr e-planorbis Beds contain Ostrea liassica and Modiola 

minima in every bed, and have also yielded Rhynchonella calcicosta, Cardinia 

crassiuscula and Lima punctata; while the last, together with L. gigantea, 

Gryphcea arcuata and Heterastrcea latimceandroidea, have been obtained from 

the planorbis zone. 

The vertebrates that have made Street famous are Ichthyosaurus intermedins 

and I. tenuirostrisy Plesiosaurus etheridgei (= P. hawkinsi), P. megacephalus 

and P. macrocephalus, and the fish, Amblyurus, Dapediusy Leptolepis, 

and Pholidophorus. 

The only indication of the higher beds of the Lower Lias of special interest 

in this district is at Marston Magna, north-east of Yeovil, where there is a 

lenticular layer of stone, composed almost entirely of a mass of small ammonites, 

with the white nacreous layer well preserved, the commonest being 

Promicroceras marstonense Spath. The stone was formerly polished and sold 

as Ammonite Marble or MARSTON MARBLE, but it is not visible in situ at the 

present day. Supplies are thought to have been obtained from an old marl 

pit in the eighteenth century, and a large mass was once discovered by the 

sinking of a well. 1 Other species of ammonites in the Marston Marble are 

Prcederoceras ziphus (Ziet.), P. trinodum (Dunk.), Asteroceras smithi, and 

A. marstonense Spath, an assemblage which Dr. Spath considers to indicate 

perhaps a somewhat higher horizon than the supposed equivalent on the 

Dorset coast. 2 

The coast-sections about Watchet 3 are discontinuous and nowhere expose 

beds above the zone of Arnioceras semicostatum, or the top of the Shales-with- 

Beef of the Dorset cliffs. The total thickness of the Pr e-planorbis Beds, Blue 

Lias, and Shales-with-Beef-equivalent is about the same as in Dorset (130- 

50 ft.). The main limestone development, however, has moved upward from 

its position at Lyme Regis into the zones of bucklandi and semicostatum, while 

the angulatum zone consists of grey shale and marl with only occasional bands 

of limestone. The planorbis and Pr e-planorbis Beds have together shrunk to 

less than 20 ft. The absence of any conglomeratic or littoral facies so close to 

the Devonian rocks is remarkable, and may indicate that the present proximity 

to those rocks is in some measure due to faulting. That the Quantock 

Island still stood above water during the formation of the Lower Lias seems 

highly probable, however, and the lack of any littoral facies close to the shore is 

paralleled on the southern flank of the Mendip Island, where it is especially 

well displayed in the Rhaetic Beds of Shepton Mallet (see above, p. 104). It is 

probably attributable to the small size of the islands and lack of streams 

bearing sediments into the surrounding sea. 

(c) The Continuation of the Dorset-West Somerset Area on the Coast 

of Glamorgan 

The zonal equivalents of the Dorset and West Somerset Blue Lias and Preplanorbis 

Beds are continued on the opposite side of the Bristol Channel in 

1 H. B. Woodward, 1893,7.^.5., p. 84. 

2 L. F. Spath, 1925, The Naturalist, pp. 305-6. 

3 H. B. Woodward, 1893, J.R.B., pp. 91-7. There are some good photographs in L. 

Richardson, 1914, P.G.A., vol. xxv, pp. 97-102.

] 24 THE LIAS 

the Vale of Glamorgan. They are exposed in the cliffs at Penarth and Lavernock, 

and between Barry and Southerndown, the last a section about 14 miles 

in length (fig. 21). The most easterly occurrences are in the form of outliers 

at Penarth, Lavernock, Leckwith, and St. Fagans, where the best exposure is 

afforded by the cliffs at Lavernock, that at Penarth being inaccessible. The 

highest beds preserved in these outliers belong to the angulatum zone. West 

of Barry, on the main outcrop, the bucklandi zone is also present, and probably 

that of semicostatum. The Lower Lias of Glamorgan has been studied in detail 

by Prof. A. E. Trueman, from whose accounts the following particulars are 

derived. 

The facies of the rock in the eastern part of Glamorgan is normal and 

resembles that on the Somerset coast, except that there is a great thickening 

of the zones up to that of semicostatum to 300 ft., or double their thickness in 

Dorset and West Somerset. There is also a noticeably greater proportion, 

amounting to a preponderance, of limestones. 

SUMMARY OF THE LOWER LIAS OF EASTERN GLAMORGAN 1 

Semicostatum Zone (= SHALES WITH BEEF OF THE DORSET COAST). 

About 50 ft. of limestones and shales with nodules are assigned tentatively 

to this zone, but the only ammonite they have yielded is Arnioceras bodleyi 

(J. Buckman). They form the highest part of the cliff west of the mouth of 

the River Daw. 

Bucklandi, Angulatum and Planorbis Zones, c. 265 ft. (=BLUE LIAS OF 

DORSET). 

The Blue Lias forms most of the long stretch of cliffs from Barry to Nash 

Point and Dunraven, but west of Nash Point towards Dunraven a littoral 

facies is developed, which will be dealt with in the next section. 

At the top is an uncertain thickness (? 60 ft.) of shale, in the lower part of 

which Gryphcea aff. incurva is so abundant that the shells make up fully onehalf 

of the rock. These shales yield Paracoroniceras cf. gmuendense. Below 

come about 80 ft. of limestone bands with Coroniceras rotiforme (2-30 ft.), 

Metophioceras cf. conybeari (40 ft.), and M. cf. rougemonti (15 ft.). The base 

of the limestones, which corresponds with the base of the bucklandi zone, 

forms a conspicuous ledge projecting from the cliff, and in it occurs the coral 

Montlivaltia haimei (abundant near Sea Mouth), together with Lima gigantea 

and Gryphcea aff. obliqua grown to a large size. 

The angulatum zone below (about 100 ft.) is more argillaceous than the 

bucklandi zone, consisting chiefly of shales with bands of small nodules. At 

Lavernock, however, where the lower 40 ft. are known as the Lavernock 

Shales, the upper 50 ft. contain a considerable percentage of limestone bands. 

The ammonite succession determined by Prof. Trueman is as follows: 

Scamnoceras angulatum and other spp. . . c. 50 ft. 

S. spp. and Alsatites spp. . . . c. 30 ft. 

S. spp. and Caloceras spp. . . . . c. ?20 ft. 

Wcehnoceras spp. and Caloceras spp. . . 6ft. 

The planorbis zone is well seen only at Lavernock. It consists of alternate 

1 A. E. Trueman, 1920-30; for list of papers see Bibliography.

LOWER LIAS: GLAMORGAN 125 

bands of shale and hard, blue, 

nodular limestone, with Ostrea 

liassica, &c. P. planorbis is found 

only in the lowest 5 ft., where it 

is abundant, while the remaining 

20 ft. are characterized by Caloceras 

johnstoni and allied species. 

PRE-PLANORBIS BEDS, C. 20 ft. 

These consist of well-bedded 

but thin limestone bands, with 

shale partings, the whole abounding 

in Ostrea liassica. In addition 

Lima gig ant ea, Modiola yPleuromy a 

and other molluscs, with Saurian 

bones, are recorded. 

II. T H E L I T T O R A L FACIES OF 

G L A M O R G A N 

From Dunraven Castle westward 

in the cliffs to Southerndown 

and Sutton a remarkable littoral 

facies is developed. The lower 

zones may be seen lapping in turn 

against a rising floor of eroded 

Carboniferous Limestone, and as 

they approach within half a mile 

of the old shore they pass into 

blue and white limestone and conglomerate. 

In these deposits there 

is little arenaceous material derived 

from the Upper Carboniferous 

rocks of the mainland, such as was 

poured into the sea about Bridgend 

in Rhaetic times. It is clear that 

the sediment is almost entirely the 

waste from the Carboniferous 

Limestone of Cowbridge Island. 

With the close of the Rhaetic 

period a further submergence had 

taken place, causing the Liassic 

sea to flood the greater part of the 

island. Across the centre a channel 

was opened up from north to 

FIG. 21. Section of the Lower Lias in the 

cliffs from near Sutton to Nash Point, 

Glamorgan, showing the distribution of 

the zones and rock-types. From A. E. 

Trueman, 1922, Proc. Geol. Assoc., vol. 

xxxiii, plate 10.

120 

THE LIAS 

south, and Prof. Trueman considers that the remainder was separated into 

four islets, upon which the sea continued to encroach during Liassic times. 

On the line of section cut by the modern cliffs of Southerndown and Sutton, 

a portion of the island still remained above the surface during the planorbis 

secule, but the water passed over it about the middle of the angulatum secule, 

and all through late angulatum and bucklandi times it was submerged beneath 

the sea. 

The littoral deposits are of two kinds: above, are dark blue limestones, 

weathering dull brown, irregularly bedded, sometimes feebly nodular, with 

seams of shale and bands of small Carboniferous Limestone pebbles; this 

type is known as the SOUTHERNDOWN SERIES. It merges downwards into 

the second type, a white or pale cream, massive limestone, frequently conglomeratic 

at the base, called the SUTTON STONE. 

The origin and correlation of these two types of deposits have given rise 

to a great deal of discussion in the past, but their significance and relations 

have now been elucidated by Prof. Trueman. 1 By more detailed zonal work, 

he has shown that each zone in turn passes laterally first into Southerndown 

Beds' and then into 'Sutton Stone' as it approaches its own shore-line. 

Consequently, at any given point, the Sutton Stone always underlies the 

Southerndown Series, which in turn grades up into normal limestones and 

shales (fig. 22). Thus from Dunraven to Pant-y-Slade and Sutton, the 

planorbis zone is seen only in the form of Sutton Stone, and thins out against 

the Carboniferous floor before Pant-y-Slade is reached. Where it is banked 

against steep-sided Carboniferous Limestone, the conglomerates are thick and 

some of the boulders are several feet in diameter. The angulatum zone resting 

on it consists of normal shales-with-nodules in the east, passing into Southerndown 

Beds farther west, and finally into Sutton Stone at Pant-y-Slade. The 

bucklandi zone overlapped so much farther west that in the upper part the 

normal limestones and shales extend almost to Pant-y-Slade, but the greater 

part of the zone is represented there by Southerndown Beds. The Sutton 

Stone facies of the bucklandi zone, which presumably lies underground 

farther inland, is not seen. 

Petrologically, the Southerndown Series consists of angular and subangular 

fragments and pebbles, chiefly of Caninia Oolite and chert in a hardened 

calcareous mud. The Sutton Stone matrix varies from hard crystalline calcite 

to limestone formed of ground and rounded shell-fragments. In places it is 

shelly and may contain abundant corals, chiefly broken. 

In the channel between the Cowbridge Island and the mainland of the 

South Wales Coal-field, the Lower Lias is chiefly of normal shale and limestone 

facies. About Bridgend this condition stands in marked contrast with the 

sandstone facies of the Rhaetic. In Liassic times sediment seems to have 

been derived no longer from rainfall on the mainland, but almost entirely 

from solution and erosion of the Carboniferous Limestone islands and comminution 

of the shells and corals on their shores. 

Around these islands the water was sufficiently free from the prevalent 

mud-bearing currents to allow a rich coral colony to thrive. In the limited 

number of exposures no evidence has been seen that the corals formed actual 

reefs on the shores of the islands, but in a quarry at Brocastle, now overgrown, 

1 A. E. Trueman, 1922, P.G.Avol. xxxiii, pp. 245-84.

LOWER LIAS: GLAMORGAN 127 

Charles Moore described the corals as growing upon boulders and encrusting 

cracks in the Carboniferous Limestone sea-bed. 

This quarry showed Sutton Stone facies of the upper part of the angulatum 

zone or possibly the bucklandi zone, almost a solid mass of organic remains, 

resting in hollows in the Carboniferous Limestone. It was vividly described 

by Duncan, to whom we owe our knowledge of the corals: 

'Some of the fossils are perfect even in their most delicate ornamentation; others 

are worn, having been rolled; and myriads are in fragments. The smaller fossils 

PANT y 5LADE E. OF D U N R A V E N 

FIG. 22. Diagrams showing the relations of the littoral deposits in the Lower 

Lias near Sutton and Dunraven and at Pant-y-Slade to each other and to 

the Carboniferous Limestone. From A. E. Trueman, 1922, Proc. Geol. Assoc., 

vol. xxxiii, figs. 60, 61. (The Conventional shadings for the different facies of 

the Lias are explained on fig. 21.) 

stud the blocks, and consist for the most part of Madreporaria and Pentacrinites, of 

Cidaris spines and plates, and of fragments of large and small Lamellibranchiata; 

and with these are mixed the shells of tiny Gastropoda. The larger fossils consist 

of perfect spheres of Isastrcea globosa Dune, (and fragments of them), of blocks more 

or less gibbous of another Isastrcea, of flat or dendroid pieces of Astroccenice, and of 

more or less fragmentary Thecosmilice and Montlivaltice; and amidst these are more 

or less perfect Cerithia, Turrit elite, large Pleurotomarice, Straparolli, Neritop sides, 

many rugged Ostrece, and more or less perfect Limce. There are also Polyzoa and 

Serpulce. All are mingled together, and here and there are some remanie species of 

Syringopora, Amplexus, Cyathophyllum, and LithostrotionS 1 

Long lists of mollusca were published by the early geologists from the 

Sutton Stone of Glamorgan, but since many of the identifications are doubtful 

8.">«7l 

1 P. M. Duncan, 1867, Q.J.G.S., vol. xxiii, p, 14. 

K

120 THE LIAS 

and the nomenclature is in need of revision, little purpose would be served 

by repeating them. The subject is one which would repay attention by a 

specialist. The corals are extraordinarily abundant for the Lias, in which 

corals are known but rarely in other parts of England. 

III. T H E M E N D I P AXIS 

The neighbourhood of the Mendips remained a region of intermittent disturbance 

after the original anticlinal uplift in Armorican times, until well into 

the Mesozoic. Not only the Rhaetic Beds, as we have seen in the last chapter, 

but also the Lias and Inferior Oolite thin out and pass into semi-littoral 

deposits, overlapping on to the Triassic marls and even the Carboniferous 

and Devonian rocks as they approach the flanks of the hills. 

A curious semi-littoral facies is seen in the neighbourhood of Chewton 

Mendip, on Harptree and Egar Hills, and near Emborrow and Binegar. 1 

Here the basal zone of the Lias with P. planorbis and C. johnstoni and other 

fossils appears as a brown, grey or white chert, resting on ochreous sand with 

seams of clay, from which ochre was formerly obtained. The total thickness 

is nearly 30 ft., but the lower parts of the series, at least in places, are of 

Rhaetic age. The siliceous condition of the rock is thought to have been 

brought about by the infiltration of hot silica-bearing water from some subterranean 

intrusion, for nearby, the Lower Lias maintains its normal characters 

of argillaceous limestones and clays, with an oyster-bed of Ostrea liassica 

in a sandy limestone at the base. 

On Broadfield Down also, the lower zones of the Lias overlap the Rhaetic 

and rest on the Carboniferous Limestone, where they take on a Sutton Stone 

facies as in Glamorgan. 

At a slightly greater distance from the old shore-lines, about Radstock, 

Paulton and Timsbury, the Lower Lias is of more normal appearance, but all 

the zones except the uppermost are much condensed, while some contain 

beds of phosphatic nodules together with fossils derived from lower zones; 

others are absent altogether. 

The long-continued researches of Mr. J. W. Tutcher of Bristol and Prof. 

A. E. Trueman have shown that, in contrast to the southern side of the 

Mendips, where deposition continued steadily throughout Liassic times, the 

northern flanks were an area of continued submarine disturbance, of erosion 

and redeposition. The shallow seas were particularly favourable to ammonite 

growth, and the wealth of their entombed shells has enabled the history of 

events to be made out in considerable detail. 

The downward limit of the Lias is easily defined hereabouts by the Sun 

Bed at the top of the Langport Beds. The upward limit is usually the base of 

the Inferior Oolite or, in places, up to 9 ft. of sands, marl and ironshot limestone 

belonging to the Upper Lias. 2 

The total thickness of the Lower Lias in the Radstock district is very 

variable. The maximum may be 190 ft., but of this 120 ft. belong to the davcei 

zone, represented by normal clays, while the whole of the remaining zones are 

compressed into from 20 to 25 ft. of strata. 

1 H.B.Woodward, 1893,^.5.,p. 123. 

2 The Middle Lias seems to be absent altogether.

LOWER LIAS: RADSTOCK 129 

SUMMARY OF THE LOWER LIAS OF THE RADSTOCK DISTRICT 1 

Davoei Zone (= GREEN AMMONITE BEDS OF DORSET). 

This zone is exposed at only a few places, notably Clandown Colliery 

Quarry, Radstock, and Huish Colliery Quarry, where 8 ft. of grey-green shaly 

clay, with rare specimens of Liparoceras, are exposed, immediately overlain 

by the Inferior Oolite. At other places, however, where exposures are lacking, 

there were synclines in which the clays were spared by the Bajocian Denudation, 

and their thickness is estimated at 120 ft. 

Ibex and Jamesoni Zones (= BELEMNITE MARLS OF DORSET). 

The Belemnite Marls of Dorset are represented by from 6 ft. to 10 ft. of 

limestone, in which belemnites are much less abundant, although still common. 

At the top there is occasionally a hard, splintery bed with Tragophylloceras 

ibex and Acanthopleuroceras valdani. Below this is the main Jamesoni 

Limestone; and at the base an 'Armatum' Bed, ironshot and rubbly, and containing 

numerous derived ammonities and phosphatic nodules in the lower 

part. The JAMESONI LIMESTONE is uniform over a wide area and shows no 

signs of having undergone erosion. North of Timsbury Sleight and Paulton 

it passes into normal clays. The 4 Armatum' Bed, however, is absent from 

Timsbury to the neighbourhood of Dundry, having been apparently removed 

from the crest of an anticlinal uplift. 

Raricostatum, Oxynotum and Obtusum Zones ( = BLACK VEN MARLS OF 

DORSET). 

This division is the most attenuated of all, the raricostatum zone consisting 

of from an inch to a foot of clay, the obtusum zone of a line of derived fossils 

and phosphatic nodules, and the oxynotum zone being absent altogether. The 

Obtusum Nodule Bed rests on various lower zones in different places and contains 

fossils derived from their denudation; it is, in fact, a typical remanie bed. 

The denudation marked by the Nodule Bed seems to have followed general 

uplift along the Mendip Axis. Movements continued during the raricostatum 

secule, causing great restriction of deposition: the fossils were exhumed and 

reinterred repeatedly, so that the true sequence is rarely discernible. 

Semicostatum, Bucklandi, Angulatum and Planorbis Zones (= SHALES 

WITH BEEF AND BLUE LIAS OF DORSET). 

The upper part of the angulatum zone and lower part of the bucklandi zone 

are absent, but the rest of the Blue Lias is rather less attenuated than some of 

the higher divisions. The Prt-Planorbis Beds and the planorbis zone are 

normally developed, consisting of from 2 to 30 ft. of limestone bands with 

shale partings, crowded with Ostrea liassica. Similar conditions seem to have 

continued into the earlier part of the angulatum secule. Deposition then 

ceased in the middle of the angulatum secule and a series of E.-W. folds, with 

a slight eastward pitch, came into being to the north of the Mendips and 

parallel with the main axis, gradually decreasing in intensity away from the 

hills. The crests of the uplifts suffered penecontemporaneous erosion, until, 

1 J. W. Tutcher, 1917, Q.J.G.Svol. lxxiii, pp. 278-81; and J. W. Tutcher and A. E. 

Trueman, 1925, ibid., vol. lxxxi, pp. 595-666.

Angulahum Caloceras Langporrensts 

Mitej 

FIG. 23. Sketch-map showing approximately the age of the strata upon which the 

Bucklandi Bed was deposited in the Radstock district, after the Sinemurian Denudation. 

(From Tutcher and Trueman, 1925, loc. cit., fig. 11 combined with fig. 2.) 

(Compare fig. 36, p. 199.)

LOWER LIAS: RADSTOCK 131 

towards the end of the bucklandi secule (in the hemera of the genus Euagassiceras), 

a general subsidence brought about the renewal of deposition. The 

erosion of the anticlinal crests has been termed by Tutcher and Trueman 

the Sinemurian Denudation (see figs. 23, 24). 

The first stratum to be deposited across the eroded crests of the anticlines 

and in the synclines was a thin remanie-bed from a few inches to a foot thick, 

known as the Bucklandi Bed from its containing abundant Coroniceratids; 

over this was laid a layer of the large brachiopod, Spiriferina walcotti. The 

brachiopods are in fine preservation and are so abundant that several of the 

SpiriFcrina bed 

obtusum nodu/esi 

Spiriferina bed* 

obtusum noduies 

Spiriferina bed 

Farmborough Timsbury Clandown Wellsway Tyning Farm 

FIG. 24. Diagrams illustrating successive stages in the deposition of the Lower Lias near 

Radstock. (Compare fig. 26.) After Tutcher and Trueman, 1925, loc. cit., fig. 10. 

exposures are famous for the products of the Spiriferina Bed. Finally, the 

Spiriferina Bed was sealed by up to 5 ft. of clay (the Turneri Clay). Signs that 

erosion still continued during the deposition of this clay are evident from the 

inclusion of partly fossilized and broken shells. 

The Lower Lias history of the shallow and unstable region to the north of 

the Mendips may be summarized as follows: while deposition of the earlier 

zones was in progress the sea-bed was thrown into a series of E.-W. folds, 

decreasing in intensity northward, away from the main axis of the Mendip 

Hills. Repeated partial denudation of the crests of the folds resulted in the 

overlapping by the Bucklandi Bed and Spiriferina Bed of all the underlying 

zones down to the White Lias about Radstock, the Sinemurian deposits 

coming to be best preserved in a shallow syncline around Keynsham. Later, 

a general uplift along the Mendip Axis caused renewed denudation of the 

Turneri Clay in the south and the formation of the Obtusum Nodule Bed; after 

which the later zones were laid down conformably upon a sea-bed that had at 

last reached temporary stability.

Farmborough Timsbury We I Is way Kil^rsdon T & 

W.L. 

St = Striatum Clay 

J = Jamesoni Limestone 

A = Armatum Bed 

R = Raricostatum Clay 

O = Obtusum Nodules 

T = Turneri Clay 

B = Bucklandi Bed 

Ang = Angulatum Zone 

PI = Planorbis Zone 

FIGS. 25 and 26. Diagrams representing exposures of Lower Lias in the 

Radstock district, along two lines running nearly due north and south; the 

upper line west of the lower. From J. W. Tutcher and A. E. Trueman, 1925, 

Quart. Journ. Geol. Soc., vol. lxxxi, pp. 600, 612.

LOWER LIAS: MIDLANDS 133 

IV. THE MIDLAND PLAINS 

(a) From the Severn to the Witham at Lincoln 

North of Bath the outcrop grows narrower, until between Wotton under 

Edge and Berkeley it occupies a strip less than a mile wide between the 

Cotswold escarpment and the Lower Palaeozoic rocks of the Tortworth inlier. 

Little is known of the stratigraphy in this region, but the Lower Lias seems 

to be considerably diminished in thickness over the buried continuation 

of the Malvern Axis (see fig. 12, p. 68). 

Then in the Vale of Berkeley below Stroud, where the Lower Oolites turn 

north-eastward and the Palaeozoic outcrop continues due north, across the 

Severn to May Hill and the Malverns, the Lower Lias and Trias tracts w r iden 

rapidly. 

The Lower Lias forms the broad and fertile Vale of Gloucester, merging 

northward into the fruit district of the Vale of Evesham and Worcestershire. 

Long tongues reach northward as far as Droitwich and Henley in Arden, and 

are continued in a small outlier at Knowle, almost on a line between Birmingham 

and Coventry, 24 miles north of the farthest projection of the North 

Cotswolds. 

As might be expected, such widening of the outcrop is commensurate with 

great expansion in thickness. A deep boring at Mickleton in the Vale of 

Evesham proved a thickness of 960 ft. of Lower Lias; but this is probably 

exceptional. Another boring at Batsford (Lower Lemington) only 7 miles 

away, in the Vale of Moreton, proved only some 500 ft. and there is attenuation 

southward and eastward, though something approaching the thickness at 

Mickleton may be maintained near the northern margin of the outcrop in 

Warwickshire and Worcestershire. 

Beyond, the formation continues to form wide clay vales and spreads over 

much of the Midland Plain, by way of Rugby, Leicester, Melton Mowbray, 

and the Vale of Belvoir to the Witham Valley in Lincolnshire, where the outcrop 

is much obscured by alluvium. A general attenuation sets in north of 

Rugby, until of 750 ft-650 ft. in Leicestershire and the borders of Lincolnshire, 

only 300 ft. remains at the Humber. 

South and east of the main outcrop, narrow feelers of Lower Lias invade 

the Oolite hill-masses along the valleys of the Rivers Evenlode, Cherwell, 

Nene, and Welland. Still farther down the dip-slope, under the covering of 

oolitic rocks, the Lower Lias has been pierced in deep borings and found to 

thin out to 450 ft. at Burford Signett, 460 ft. under parts of Northamptonshire, 

and 228 ft. at Clay don (Calvert), on the Oxford Clay outcrop south of 

Buckingham. This thinning was proved to be accompanied by overlapping of 

the higher zones over the lower, for in the Calvert boring the jamesoni zone 

was found to be resting directly on the Palaeozoic floor of Shineton Shales. 1 

Throughout the long tract from the Severn to the Witham there are few 

features meriting special attention. The great thickening in Gloucestershire 

and Worcestershire is mainly due to the expansion of the clays, but farther 

north the Blue Lias limestones come in again in force. These last, known in 

this part of the country as the Hydraulic Limestones, are exposed in numerous 

1 A. \I. Davies and J. Pringle, 1913, Q. J.G.S., vol. lxix, pp. 311-14.

120 THE LIAS 

lime and cement works, but the overlying clays are proportionately as rarely 

exposed as in West Somerset, and for the same reasons. 

The full succession of zones has been elucidated in several districts, notably 

about Cheltenham, Gloucester and the Vale of Evesham, in Northamptonshire, 

and in South Lincolnshire. The epiboles detected in the western 

district are appended in the table on page 28, compiled from the works of 

Prof. Trueman and Miss D. M. Williams, largely from collections made 

by Mr. L. Richardson. A comparison of the table with that portraying the 

succession in the Radstock district shows that, although the raricostatum zone 

is represented in both districts, the faunas contained in it are largely different. 

Probably the best section of the clays of the upper zones is to be seen in the 

Battledown Brickworks, Cheltenham, where the ibex and the lower half of the 

davcei zones can be studied. The section is continued into the upper half of 

the davcei zone by a brickworks at Aston Magna. 1 Knowledge of the great 

mass of the central parts of the Lower Lias in this region, however, is derived 

from small temporary openings and old railway-cuttings now overgrown. 

In Warwickshire, Northamptonshire and South Lincolnshire all the zones 

have been recognized in various brickyards, cuttings and boreholes, but the 

epiboles still remain to be worked out in detail. The most remarkable addition 

to the palaeontological succession was a blue clay abounding in Rhynchonellids 

and the ammonite Coeloceras pettos, encountered in a cutting on the railway 

near Flecknoe. 2 The position of this bed is between the jamesoni and 

ibex zones, and Mr. Beeby Thompson has suggested raising it to the rank of 

a new zone. The ammonite has been found also in the Dorset cliffs, where its 

position has been fixed by Dr. Lang in his table of epiboles in the jamesoni 

zone. 

Another interesting feature, formerly seen in a railway-cutting 1 mile south 

of Rugby, was an exposure, 25 ft. deep, of the oxynotum zone, yielding over 

a hundred species of fossils, especially great numbers of Hippopodium ponderosum 

and Dentalium etalense. 3 The true Oxynoticeras oxynotum, which does 

not occur on the Dorset coast, was here found in hundreds, associated with 

O. biferum. 

Occasionally large corals of the genus Montlivaltia occur at various levels— 

M. rugosa forms a thin coral bed in the raricostatum zone of Marie Hill Brickyard, 

Cheltenham; M. victorice occurs in a hard band in the davoei zone, 

formerly polished and sold as Banbury Marble at Banbury; M. mucronata has 

been found in the jamesoni zone near Wolfhamcote, Northants; M. mucronata 

and M. haimei were found in the tunnel between Old Dalby and Saxelby on 

the railway from Melton Mowbray to Nottingham, which passed through the 

oxynotum, raricostatum, jamesoni, ibex, and possibly davoei zones. 4 

The lower zones of the Lower Lias are well known owing to the extensive 

exploitation of the Hydraulic Limestones for lime and cement. 

The best inland exposure in England is at Victoria Quarry, Rugby, 5 where 

the limestones are 70 ft. thick (about the same thickness as in Dorset), con- 

1 L. Richardson, 1929, 'Geol. Moreton in Marsh', Mem. Geol. Surv., pp. 12-15. 

2 B. Thompson, 1910, 'Geol. in the Field', p. 456; and 1899, Q.J.G.S., vol. Iv, pp. 65-88. 

3 B. Thompson, 1910, loc. cit., p. 455. 

4 For list of fossils collected on the tip heaps thrown out in the making of the tunnel see 

Trueman, Geol. Mag., 1918, pp. 101-2. 

s H. B. Woodward, 1893, J.R.B., p. 163.

LOWER LIAS: SHROPSHIRE OUTLIER 135 

sistingof upwardsof 3 5 bands of limestone with shale partings. The ammonites 

shew that the planorbis (johnstoni subzone), angulatum and bucklandi zones are 

represented, and as usual Saurian and fish remains are present (fragments of 

Ichthyosaurus, Plesiosaurus, &c.). 

In Nottinghamshire and South Lincolnshire the Hydraulic or Blue Lias 

Limestones are about 25 ft. thick, and seem to include only the Prt-planorbis, 

planorbis, and angulatum zones. The Prt-planorbis deposits consist largely of 

fine-grained calcitic mudstones with bands of Ostracods and Foraminifera, 

suggestive of formation in lagoons. 1 

In the part of Warwickshire lying over the Sedgley-Lickey Axis, about 

Binton, Grafton, Wilmcote, and Bickmarsh, the Lower Lias has cut down 

through the Langport Beds of the Rhaetic, for it has at the base a conglomeratic 

layer known as the Guinea Bed, which contains a Lower Lias fauna with an 

admixture of derived Rhaetic fossils, and over the area of its occurrence the 

Langport Beds are absent. In the region of the Nuneaton Axis also, a mile 

or two south and west of Rugby (at Church Lawford) the Pre-planorbis Beds 

are absent and the planorbis zone rests non-sequentially on an eroded surface 

of the Langport Beds. 

(b) The Shropshire and Cheshire Outlier 2 

The former continuation of the Lias far to the north of its present outcrop 

in the Midlands and West of England is proved by a basin-shaped outlier of 

Lower and Middle Lias in North Shropshire and South Cheshire. The outlier 

measures some 10 miles in length and about 3 to 4J miles in breadth and, 

although largely Drift-covered, it rises into prominent hills between Whitchurch 

and Ightfield and at Prees, the highest part being capped with Middle 

Lias Marlstone. 

The Lower Lias is only exposed meagrely in the sides of small brooks, 

and the information is mainly derived from borings. Both lithologically and 

palaeontologically, it is evidently a continuation of the main outcrop of 

Gloucestershire and Worcestershire, consisting for the most part of finely 

laminated shale, with occasional hard calcareous mudstone bands and layers 

of cementstone nodules. The total thickness is probably more than 400 ft. 

A typical Lower Lias fauna has been obtained from the borings, and the 

ammonites prove the presence of the planorbis, angulatum, bucklandi, semicostatum 

and jamesoni zones. Near Burley Dam the shales are hard enough 

to have been used in the past for roofing-slates. 

The presence of Rhaetic Beds is strongly suggested by a record of Protocardia 

rhcetica, but no other evidence has been obtained. 

(c) Lincoln to the Humber: the Frodingham Ironstone District 

On the main outcrop north of Lincoln the Lower Lias continues to form 

low-lying ground, largely covered by Boulder Clay, marshland and alluvium, 

as far as the village of Scotter. North of this, for the last 16 miles to the 

Humber, the width of the outcrop averages 4 miles, and the limestones of the 

angulatum and bucklandi zones form an increasingly prominent ridge running 

1 A. E. Trueman, 1915, Geol. Mag. [6], vol. ii, pp. 150-2; and 1918, ibid., vol. v, pp. 64-73, 

101-3. 

2 H. B. Woodward, 1893, J.R.B., pp. 180-3.

120 THE LIAS 

S.-N. between the Oolite escarpment on the east and the Trent Valley on 

the west. 

The tract east of this ridge, separating it from the Oolites, is of exceptional 

interest owing to the development of a ferruginous facies of the upper part of 

the bucklandi and perhaps also part of the semicostatum zones. The wellknown 

Lincolnshire or FRODINGHAM IRONSTONE, which has given rise to the 

modern industrial town of Scunthorpe, has been quarried from large areas, 

leaving vast shallow pits, now cultivated or full of water; and active quarrying 

by modern methods directly into railway trucks is still carried on along 

numerous working faces ramifying out for several miles both to north and 

south of the smelting furnaces (Plate IV). 

The total thickness of Lower Lias in the ironfield is just over 400 ft., and it 

is usually divided into three groups: 1 

Upper Clays (maximum 200 ft.). 

Frodingham Ironstone (25-30 ft.). 

Lower Clays and Limestones (200 ft.). 

Davoei-Obtusum Zones (THE UPPER CLAYS). 

The uppermost 66 ft. of clays contain Androgynoceras capricornum throughout 

and therefore belong to the davoei zone. Below this is a 4 ft. band of ironstone 

known as the Pecten Bed from the abundance of P. cequivalvis and 

P. lunularis, together with other shells such as Cardinia listeri, C. hybrida, 

Pseudotrapezium intermedium, Gryphcea spp., Lima hermanni, Modiola sealprum, 

and brachiopods. 

Between the Pecten Bed and the Frodingham Ironstone, the clays were 

proved by borings to thin from south to north from 140 ft. south-west of 

Kirton Lindsey Railway Station to 90 ft. south of Appleby Railway Station. 

The records of ammonites from the Pecten Bed and the clay below it date 

from a time when identifications were made with little refinement, and they 

need revision by careful collecting. Cross 2 (who is followed by the Survey) 

stated that the Pecten Bed was full of Ammonites striatus and A. henleyi (both 

davoei zone) and also A. armatus. Either the last is a misidentification, or the 

records from the underlying clay are faulty, since they include A. henleyi, 

A. [Androgynoceras] latcecosta, A. capricornum, A. [Tragophylloceras] loscombi 

(all davoei zone), A. [.Phricodoceras] taylori (base of jamesoni zone) and A. 

[.Echioceras] raricostatum. From these records it would seem that there is a 

great expansion of the davoei zone, which includes the Pecten Bed, all of the 

clays above it and part of those below it. An Oxynoticeras, however, occurs 

in the clays not far above the main ironstone. 

Bucklandi Zone (Pars) and Semicostatum Zone (THE FRODINGHAM IRON- 

STONE). 

The ironstone is best described as a ferruginous oolitic limestone. The iron 

is originally present in the form of carbonate, but towards the surface it has 

been weathered to hydrated oxide. A quantity of iron silicate is also present 

and colours the Cardinias and other shells a bright green. Weathering is 

1 Based mainly on W. A. E. Ussher, &c., 1890, 'Geol. N. Lines.', Mem. Geol. Surv., 

pp. 12-50. 

2 1875, Q.J.G.S., vol. xxxi, pp. 118-20.

LOWER LIAS: FRODINGHAM IRONSTONE 137 

accompanied by obliteration of the oolitic structure, until on the removal of 

all the carbonate the rock becomes soft, incoherent, and purplish-brown in 

colour. The average iron-content is only 21-8-22-7 per cent, and the limecontent 

as high as 18-2 per cent, on account of the prevalence of bands of 

shells. 1 The most conspicuous are Cardinia of several species, Gryphcea cf. 

cymbium, Lima gigantea and L. hermanni, together with Pectens, Pholadomya 

ambigua and Spiriferina walcotti, which all occur in perfect preservation. 

Large specimens of a Coroniceras, probably Paracoroniceras gmuendense, 

occur in the lowest 5 ft. of the ironstone, while from the higher parts are 

obtained an ammonite which has usually been known as A. semicostatus. 

Various species of Arnioceras, however, are common at several horizons in 

the bucklandi zone, and Dr. Spath avers that the species recorded as A. semicostatus 

has been misidentified, the true Arnioceras semicostatum (Y. and B.) 

belonging to a higher level; and consequently that the true horizon of the 

Frodingham Ironstone is about gmuendense-/Etomoceras-Agassiceras epiboles 2 

(i.e. bucklandi zone). Support is given to this view by the old record from the 

ironstone of Metophioceras conybeari, which may be seen by reference to Dr. 

Lang's sequence on the Dorset coast (p. 28) to occur below Paracoroniceras 

gmuendense, at the very base of the bucklandi zone. 

Bucklandi, Angulatum, Planorbis and Pre-Planorbis Zones (THE LOWER 

CLAYS AND LIMESTONES). 

Two hundred feet of grey and blue, compact, often nodular, limestones, 

interstratified with shales, build the escarpment west of the ironstone workings, 

overlooking the Valley of the Trent. Certain bands contain thousands of 

Gryphcea arcuata, while Lima gigantea, L. hermanni and Cardinia listeri are 

conspicuous. The ammonites recorded are Coroniceras bucklandi, Metophioceras 

conybeari (bucklandi zone), Scamnoceras angulatum (angulatum zone) and 

Caloceras johnstoni (planorbis zone); but Psilocer as planorbis is, according to 

Cross, entirely absent. The lowest 20 ft. contain the fauna of the Preplanorbis 

Beds—Ostrea liassica, Pleuromya crowcombeia, Modiola minima and 

Ichthyosaurus. 

V. THE MARKET WEIGHTON AXIS 3 

Towards the Humber the Lower Lias escarpment diminishes in importance, 

and the ferruginous facies which caused so many sections to be opened 

in the higher beds is not seen again. After disappearing under the Humber 

and the alluvial tracts on either side, the Lower Lias reappears at North 

Cave, and thence to Market Weighton the limestones and clays of the Preplanorbis 

and Planorbis Beds form a small but definite escarpment, rising 

abruptly above the Triassic plain. 

Several well-known sections formerly existed along this escarpment, but 

they are now all more or less obscured. The best w r as at the village of North 

Cliff, 4 where a lane cutting and a pit for marling the sandy land to the west 

showed 55 ft. of Planorbis and Prt-planorbis Beds. The zonal ammonite 

(flattened) was found in a blue clay 18-27 ft- from the base, while the 28 ft. 

1 C. B. Wedd, 1920, Spec. Repts. Min. Resources, vol. xii, pp. 71-105, Mem. Geol. Surv. 

2 L. F. Spath, 1922, Geol. Mag., vol. lix, p. 171. 

3 C. Fox-Strangways, 1892,J.R.B.} pp. 67-70. 

4 Detailed descriptions in J. F. Blake, Q.J.G.S., vol. xxviii, pp. 132-46.

FIG. 27. Sketch-map of the Yorkshire Basin, to show the distribution of the Jurassic rocks. The thick lines are faults.

LOWER LIAS: YORKSHIRE BASIN 139 

of alternating clay and limestone bands above yielded Caloceras johnstoni 

at several horizons, with Lima gigantea, Protocardia philippiana, Modiola 

minima, Ostrea liassica and other fossils. The Pre-planorbis Beds were also 

typical and a continuation of those south of the Humber. 

At Market Weighton the Upper Cretaceous comes to rest for some miles 

directly on the Low r er Lias. Then for 10 miles northward the Lower Lias 

forms a zone of slips along the base of the Chalk Wolds, and is much obscured 

by fallen debris. Unfortunately most of the scanty exposures are in the lower 

beds, so that it is not known how many of the higher zones are missing over 

the axis, or whether they are represented in attenuated form. The total thickness 

diminishes to 150 ft. and in places even to 100 ft. 

VI. THE YORKSHIRE BASIN 

North of the River Derwent the outcrop turns nearly due west, to sweep in 

a great arc of a circle round the oolitic rocks of the Yorkshire Basin, past 

Thirsk, Northallerton and Stokesley, to the sea south of Tees Mouth (fig. 27). 

Throughout the first half of this arc, as far as the neighbourhood of Northallerton 

(about 30 miles) the Lower Lias is virtually unknow r n by reason of the 

dearth of exposures and a thick mantle of Drift. A considerable northerly 

thickening sets in, and the limestone facies of the lower zones is less evident 

when the beds are next exposed about Foxton. 

At the foot of the escarpment of Cringley and Carlton Moor shales with 

ironstone nodules, containing ammonites of the davoei zone, are seen to a 

thickness of 150 ft., while near Carlton evidence has been obtained of the 

raricostatum, oxynotum and bucklandi zones, all represented by shales and 

marls. 

On the north side of the Guisborough valley, south of Eston Hill, a boring 

proved 426 ft. of Lower Lias without reaching the bottom. North of this the 

whole outcrop is again badly hidden by Boulder Clay, and there are no good 

sections until the coast is reached. 1 

On the coast, the lowest Lias seen is the upper part of the angulatum zone, 

which, together with the bucklandi zone, forms the island-like rocks at Redcar, 

known as The Scars. From Redcar to Saltburn the cliffs show only Drift, 

but the upper part of the Lower Lias reappears to form the lower part of the 

cliff and foreshore from Saltburn to Colburn Nab, near Staithes. 

The best section of all, however, is to be seen below the Boulder Clay in the 

lower part of the cliffs of Robin Hood's Bay, between Whitby and Scarborough 

(fig. 27), and a description of this serves as a good summary of the Lower Lias 

of North Yorkshire. All the zones down to that of semicostatum here travel 

in a series of arch-like curves round the bay, brought up above sea-level by an 

anticline, which is cut across almost at right-angles by the shore. 

SUMMARY OF THE LOWER LIAS AT ROBIN HOOD'S BAY AND REDCAR 2 

Davoei Zone (= GREEN AMMONITE BEDS OF DORSET), 155 ft. 

The davoei zone consists of a nearly uniform series of soft shale, for the most 

part sandy, with numerous rows of clay-ironstone doggers and pyritous 

1 C. Fox-Strangways, 1892,J.R.B.y pp. 63-4. 

2 Based on C. Fox-Strangways, G. Barrow, and S. S. Buckman, 1915, 'Geol. Country 

between Whitby and Scarborough', 2nd ed., pp. 7-10, 66-71; Mem. Geol. Surv.

120 THE LIAS 

nodules, often containing ammonites. The highest 30 ft. is rather sandier 

than the rest and was formerly grouped on lithological grounds with the 

Sandy Series of the Middle Lias. At the top is a 4J- ft. band of hard ferruginous 

sandstone, overlain by a band of ferruginous doggers. The sandstone 

contains layers of fossils, notably ammonites of the genus Oistoceras, with 

Protocardia truncata, Gryphcea cymbium, and abundant Dentalium giganteum 

Phil. 

The only other feature is an oyster bed, about 30 ft. from the top. This 

consists of thin sandy laminae ft.) passing into a harder calcareous band 

composed largely of Gryphcea cymbium and Oxytoma incequivalvis, accompanied 

by Oistoceras spp. and other fossils. 

Prodactylioceras davoei has not been found in Yorkshire, but the species of 

Oistoceras and Lytoceras serve for correlation of these sandy shales with the 

upper part of the Green Ammonite Beds of Dorset. 

The lowest 35J ft. of sandy shale with bands of doggers yield Androgynoceras 

spp., which characterize the lower stone band and surrounding clays in 

the Dorset Green Ammonite Beds. Buckman regarded them as of striatum 

date. 

Ibex and Jamesoni Zones (= BELEMNITE MARLS OF DORSET), 100 ft. 

These zones also consist of soft shales with bands of ironstone and pyritous 

doggers, with no lithological line of separation from the davoei zone above. 

Belemnites are abundant at certain horizons, but no recent work comparable 

with that by Dr. Lang in Dorset has been done on them. 

The upper half of the series yields ammonites of the genera Platypleuroceras 

(P. aureum and P. rotundum) and Polymorphites (P. trivialis), which 

Dr. Lang has found in Dorset in the jamesoni zone, below Uptonia jamesoni. 

It would thus seem that the ibex and the upper part of the jamesoni zones are 

unrepresented or unfossiliferous. 1 

The lowest 10 ft. of the series yields Phricodoceras taylorif which marks the 

base of the jamesoni zone in Dorset. 

Raricostatum, Oxynotum and Obtusum Zones (= BLACK VEN MARLS OF 

DORSET), 175 ft. 

These consist, like the higher zones, principally of soft shales with lines of 

nodules, but in the lower part indurated calcareous bands are intercalated, and 

some of the shale becomes harder. 

The highest 65 ft. contain abundant Apoderocerasf together with occasional 

Echioceras, and comprise the old 'armatum zone'—a series of horizons higher 

than those formerly called by the same name in Dorset, since these belong 

above and those in Dorset below the horizon of Echioceras raricostatum. The 

raricostatum horizon of Robin Hood's Bay is about 100 ft. from the top, 2 ft. 

above a conspicuous datum-line called the Double Band. Immediately above 

the two hard beds which comprise the Double Band is a horizon of Oxynoticerates, 

indicating the oxynotum zone. The raricostatum zone is therefore over 

100 ft. (about 106 ft. ?) thick. 

1 Buckman wrongly supposed that Platypleuroceras and Polymorphites indicated the valdani 

(= ibex) zone, and the rare fragments occurring below, which he supposed to be species of 

Uptonia, were apparently misidentified. See S. S. Buckman, 1915, 'Geol. Whitby and Scarborough', 

p. 70.

L O W E R LIAS: YORKSHIRE BASIN 141 

The detailed succession of ammonites in the 65 ft. of shales below the 

Double Band has not been worked out, but about the middle Promicroceras 

planicosta has been recorded, and Asteroceras obtusum at more than one level 

below. It is therefore assumed that most, if not all, belongs to the obtusum 

zone, but there are many lacunae in the lower part. 

Semicostatum Zone (= SHALES-WITH-BEEF OF DORSET), about 45 ft. 

This is the lowest zone exposed in Robin Hood's Bay, w T here 36 ft. can be 

seen at low tide. The zone consists of blue calcareous shales with thin bands 

of limestone, 1-8 in. thick, made of comminuted shells. Arnioceras semicostatum 

amd Arietites turneri are rather abundant, together with numerous 

lamellibranchs, such as Gryphcea arcuata, Oxytoma incequivalvis, Cardinia 

listeri, Hippopodium ponder osum, Nuculanay Lima, Chi amy s, and Dentalium. 

Bucklandi, Angulatum and Planorbis Zones (= BLUE LIAS OF DORSET), 

about 230 ft. (+?). 

For the downward continuation of the section it is necessary to pass north 

along the coast to the Scars, near Redcar. Here the bucklandi zone is exposed 

for its whole thickness of about 160 ft., together with 30 ft. of the top of the 

angulatum zone. The angulatum zone is the lowest part of the Lias exposed 

on the Yorkshire coast, and can only be seen for a distance of 400 yards at low 

water opposite the battery, where it is brought up in the crest of an anticline. 

Lithologically the tw r o zones are similar, consisting of shales in which are 

numerous oyster bands formed of Gryphcea arcuata, and occasional thin beds 

of limestone. About 42 ft. from the top of the bucklandi zone is a 3-in. band 

made up of a mass of Cardinia listeri, together with some XJnicardia and 

Gryphcea arcuata. Two feet below this is a particularly rich fossil bed, 8 in. 

thick, containing nearly all the fossils found throughout the rest of the zone, 

and including occasional corals referred to Montlivaltia haimei and M. 

guettardi. M. haimei occurs lower down, 20 ft. below the top of the angulatum 

zone, in a band of fossiliferous pebble-like concretions in.) in association 

with Ornithella sarthacensis, Astarte oppeliy Cardita hebertiy Plicatula Hasina, 

and Serpulce. 

The existence of the planorbis zone beneath the sea is proved by the fact that 

blocks full of the zone-fossil are often washed up in Robin Hood's Bay. It 

has also been detected inland in some borings and small exposures, but there 

are no satisfactory sections. 

PRE-PLANORBIS BEDS, 20-40 ft. 

In the Northallerton district there are about 40 ft. of Pre-planorbis Beds, 

though not all of them are exposed in any one section. The clays partake more 

of the nature of paper-shales. Ostrea liassica as usual abounds in the upper 

part, and Pteromya crowcombeia is common throughout, but especially in a 

thin limestone band 25 ft. from the top. 1 

Wherever the Pre-planorbis Beds are exposed in other parts of the Yorkshire 

Basin the same features are displayed, and they are usually known as the 

Oyster Beds and Pleuromya Limestone. 

1 C. Fox-Strangwavs, 1886, 'Geol. Northallerton and Thirsk\ Mem. Geol. Surv., pp. 

13-14-

120 

THE LIAS 

VII. T H E C U M B E R L A N D O U T L I E R 1 

The basement beds of the Lower Lias form a plateau-outlier west of Carlisle, 

extending from near Bellevue for about 7 or 8 miles westward. The 

ground is covered with a thick mantle of Drift and the Lias is known almost 

exclusively from the cores of borings. It is at least 210 ft. thick at Great 

Orten, and consists of the usual shales with bands of limestone, some of them 

sandy and micaceous. Records of fossils are meagre, Caloceras johnstoni (upper 

part of the planorbis zone) being the only ammonite found. 2 

VIII. N O R T H E R N IRELAND: T H E A N T R I M P L A T E A U 

About 120 miles west of the Cumberland outlier the Lower Lias is again 

met with, sandwiched between Rhaetic and Cretaceous sediments beneath the 

Tertiary basalt plateau of Antrim. It suffered extensive denudation prior to 

the deposition of the Cretaceous rocks and again before the outpouring of the 

basalt. In places the Liassic and Rhaetic rocks are overstepped by the Cretaceous, 

w T hile often the basalt oversteps all three and passes on to the Trias. 

Nevertheless, the Lower Lias probably has a considerable extension beneath 

the plateau, for it outcrops at numerous points along the edge. Tate traced 

it 'on the south of the County Antrim from Collin Glen (Belfast) to Whitehead, 

also on the Carrickfergus Commons and on the shores of Lough Morne; on 

the east, around the shores of Larne Lough and on the east coast of Island 

Magee, Larne, Glenarm, and Garron Point; on the north, at Ballintoy and 

Portrush; and in the County Londonderry, at Magilligan on the NE., at 

Aghanloo, and Lisnagrib'. 3 

In places strata at least as high as the upper part of the raricostatum zone 

are preserved, for Leptechioceras macdonnellii, a species described and figured 

by Portlock in his Report of 1843, is said by him to be 'common to the Ballintoy 

marls and the indurated Lias of Portrush'. There is considerable attenuation, 

for at Collin Glen, Belfast, all the beds intervening between the obtusum 

zone with Arietites turneri and the Rhaetics occupy only 38 ft.; most of the 

series consists of marls and shales, in the highest 17 ft. of which occur 

A. turneri, S. angulatum and numerous lamellibranchs. Below, P. planorbis 

has been found, and most of the thickness is thought to belong to this zone. 4 

At the base are 4 ft. of shelly limestones with abundant Ostrea liassica and 

Modiola minima, evidently the continuation of the Prt-planorbis Beds of 

England. 

IX. T H E HEBRIDEAN AREA 

Lower Lias occurs in the islands of Skye, Raasay, Pabay (Pabba), Scalpay 

(Scalpa) and Mull, and on the mainland at Applecross, in Ardnamurchan, and 

in Morven. It is conformable with the Trias, which rests with great unconformity 

on Cambrian and older rocks. Above it the higher members of the 

Jurassic follow to great thicknesses, the highest, of Corallian, and in two places 

Kimeridgian, date, being found in Skye and Mull (see map, fig. 19, p. 114). 

1 H. B. Woodward, 1893, J.R.B., p. 183, with references. 

2 No palaeontological evidence for the presence of Rhsetic Beds has been obtained, but there 

is no reason for supposing them absent. 

3 R. Tate, 1864, Q.J.G.S., vol. xx, p. 109. 

4 G. W. Lamplugh, 1904, 'Geol. Belfast', p. 26, Mem. Geol. Surv.

LOWER LIAS: HEBRIDES 143 

As remarked in an earlier chapter, the Jurassic strata form plateaux, usually 

with gentle dips, and they are mere remnants faulted down among the ancient 

rocks which they once covered. Folding has affected them but little, but 

alteration, due to the injection of numerous sills and dykes, has often been 

profound. In Eocene times vast sheets of basalt and granophyne were extruded 

through them, covering them in places to depths of hundreds of feet. 

It is generally owing only to the protective action of these sheets of Tertiary 

igneous rock that the Jurassic and Cretaceous sediments have been preserved 

at all. 

The Hebridean Trias consists of alternations of grits, pebbly grits and conglomerates, 

which pass up into red and grey marls. The Jurassic rocks, 

however, with few exceptions, show little indication of close proximity to any 

shore-line. It cannot be too strongly emphasized that their present distribution 

is dependent upon the subsequent interaction of extraneous influences, 

and bears no relation to their original extent. 

(a) Skye, Raasay, Pabba and Applecross 

The Lower Lias has a far larger surface-area in the Hebrides than any other 

part of the Jurassic System. The principal outcrop is nearly 10 miles long and 

from 1 to 2 miles broad, crossing the central district of Strath, Skye, in a 

SW.-NE. direction, from Lochs Slapin and Eishort to Broadford Bay (fig. 

19). It is the eastern limb of an ancient anticline, initiated before Mesozoic 

times, the western limb of which has been broken down by the granite intrusion 

of the Red Hills. In the centre Cambrian limestones, dolomites and 

quartzite are arched over the granite intrusion of Beinn an Dubhaich, and 

on to them lap successively the lower zones of the Lower Lias, until on the 

shores of Loch Slapin, the Durness (Cambrian) Limestone is overstepped by 

the semicostatum zone. At the south end of the anticline the Lower Lias 

plunges steeply beneath the higher Jurassic rocks of Strathaird, while to the 

north its prolongation is proved by the remnants forming the flat island of 

Pabba and the south-eastern extremity of Scalpa. 

Into the centre of the northern end of this anticline the sea has eaten Broadford 

Bay, round which Lower Lias forms the coast for 5 miles. The greater 

part of the beds exposed belong to the lower part of the formation, consisting 

of hard limestones and sandstones spanning the Prz-planorbis to semicostatum 

zones. This lower division was therefore named by H. B. Woodward in 1896 

the BROADFORD BEDS. The upper part of the formation, consisting of shales, 

builds the whole of the island of Pabba, lying off Broadford Bay, and takes 

from it the name of PABBA SHALES. 

In spite of the hardness of the Lower Lias, it has been planed off near the 

coast almost to sea-level, an upward limit of altitude being imposed by the 

100 ft. beach. In Broadford Bay the exposures are poor and disappointing, 

consisting of little more than reefs and ledges, for the most part covered by 

the water at high tide and overgrown with seaweed. Better (and highly 

fossiliferous) exposures of the Pabba Shales are afforded by the low cliffs of 

Pabba Island, and again on Raasay. On the coasts of Loch Slapin and Loch 

Eishort the cliffs are considerable and the exposures extensive, but here the 

Lias is largely altered by heat and fossils are often destroyed. 

FTJ«71 L

120 

THE LIAS 

SUMMARY OF THE LOWER LIAS IN SKYE, RAASAY, PABBA AND APPLECROSS 1 

Davoei, Ibex, Jamesoni and Raricostatum Zones: (PABBA SHALES), 700 ft. 

in Skye, 600 ft. in Raasay. 

The shales as a rule are remarkably uniform throughout their great thickness, 

being always dark and micaceous, with mudstone nodules and thin 

lenticular bands of calcareous sandstone and argillaceous limestone at 

intervals. 

Towards the top, to a varying extent in different places, they become 

arenaceous, forming a lithological passage upward into the Middle Lias. In 

Mull there is a perfect passage from sandstones containing ammonites of the 

jamesoni and even raricostatum zones up into the Scalpa Sandstone of Middle 

Lias age. In Raasay only the davoei zone (represented by Lytoceras salebrosum( 

?) Pomp. sp. and Androgynoceras cf. maculatum Y. and B. sp.) is developed 

entirely in a sandstone facies, more conveniently classed with the 

Scalpa Sandstone. Even in Raasay, however, the Pabba Shales become gradually 

harder and more sandy in the ibex and jamesoni zones, and lenticular 

bands of calcareous sandstone are intercalated. This early incoming of the 

arenaceous sediment more properly characteristic of the Middle Lias recalls 

the Yorkshire Basin, where we saw in the last section that the lower half of the 

sandy series, at least in places, contains capricorn ammonites of the davoei 

zone. Here too, as in Yorkshire, many of the Middle Lias lamellibranchs, 

such as Pseudopecten cequivalvis and Gryphcea cymbium, first enter with the 

arenaceous facies. But the occurrence of Acanthopleuroceras valdani indicates 

that some of the strata belong to the ibex zone, while a little lower Uptonia 

jamesoni has been found. Two species of Spiriferina and giant Rhynchonellids 

of the rimosa group (Rimirhynchia of S. S. Buckman) also occur, recalling the 

jamesoni zone of Radstock. 

In the Isle of Pabba the ibex and jamesoni zones are together 100 ft. thick 

and largely form the island. They have recently been examined in detail by 

Dr. L. F. Spath, with a view to establishing the ammonite succession. 2 

The lowest beds of the island, seen on the north-eastern coasts, belong to the 

top of the raricostatum zone, but only a fraction of this zone comes to the 

surface on Pabba Island. 

The great bulk of the Pabba Shales elsewhere, as best exposed in Raasay, 

consists of a greatly expanded raricostatum zone, 300 ft. thick. This is much 

thicker than its development in any English locality, and the genus Echioceras 

is proportionately abundant, in both species and individuals, and provides 

valuable material for evolutionary study. The late Dr. G. W. Lee's collecting 

brought to light the interesting fact that there are repeated alternations of 

Echiocerates and Derocerates. The facts are capable of two very different 

interpretations, the most rational being that which postulates temporary 

migration and return of the same species with change of conditions. 3 

Of other fossils in the Pabba Shales, lamellibranchs are fairly abundant, 

especially in the upper part of the raricostatum zone, where nearly all the 

1 Based on H. B. Woodward and C. B. Wedd, 1910, 'Geol. Glenelg, Lochalsh, and SE. 

Skye\ pp. 98-113; and G. W. Lee and S. S. Buckman, 1920, 'Mes. Rocks Applecross, 

Raasay and NE. Skye', Mems. Geol. Surv. 

2 L. F. Spath, 1922, Geol. Mag., vol. lix, pp. 548-51. 

3 For further discussion of this, with references, see Chapter I, p. 30.

L O W E R LIAS: HEBRIDES 145 

characteristic species have been obtained. Hippopodium ponderosum attains 

a large size. Gastropods, on the other hand, are unusually scarce, only one 

species having been recorded. 

Echioceras abounds to within a few feet of the base of the Pabba Shales, 

which rest abruptly and non-sequentially upon the calcareo-arenaceous Broadford 

Beds. The change from the one type of rock to the other is equally 

sudden in Raasay, Applecross, Skye and Mull, and points to a widely distributed 

stratal break. This break seems to represent the oxynotum zone 

and, in most places, the obtusum zone. 

Obtusum, Semicostatum, Bucklandi, Angulatum and Planorbis Zones 

(BROADFORD BEDS), 340 ft. in Raasay, 240 ft. in Skye. 

At the top the series consists of fissile, micaceous sandstones, which pass 

down into calcareous sandstones, and finally become, for the greater part of 

the succession, alternations of black or dark blue limestone (often sandy) 

with shale partings. In Skye there are some bands of fine quartz conglomerate 

in the basal 10-15 ft. 

The upper half of the Broadford Beds is characterized by abundant 

Gryphcea arcuata, while the basal 10-20 ft. at Applecross are crowded with 

Ostrea liassica, just as are the English Prt-planorbis Beds. 

In the type-area the higher parts of the Broadford Beds, which crop out in 

the foreshore north-west of Broadford pier, are obscured by coverings of Drift 

and peat and are altered by contact with numerous dykes and sills. The 

abrupt and non-sequential junction with the Pabba Shales is, however, clear 

in the south of the island, and in Raasay and at Applecross. All round Broadford 

Bay the exposures are poor and discontinuous, the reefs being largely 

obscured by recent beach material and the succession being complicated by 

the numerous dykes. Only the lower zones are well exposed farther east, 

particularly those of bucklandi, angulatum and planorbis, which form the reefgirt 

Ardnish headland enclosing the inlet of Ob Breakish, and continue eastward 

to the small promontory and islet of Lusa. 

Combining the evidence collected by the Survey in the several localities, the 

following generalized succession can be made out: 

OBTUSUM ZONE. On Loch Eishort, Skye, the Asteroceras fauna has been 

found in a thin shale overlying the semicostatum zone, but it has not been 

recognized in Raasay. In Raasay, however, in the cliff north of the waterfall 

at Hallaig, 40 ft. of flaggy, carbonaceous, rusty-weathering sandstones, with 

a layer of Gryphcea arcuata 6 ft. from the top, have yielded Microderoceras 

birchi, Arietites turneri and other species. In Morven the zone attains a considerable 

thickness (see below, p. 148). 

SEMICOSTATUM ZONE. This zone is the most conspicuous part of the Lower 

Lias in the cliffs of Loch Slapin, where it consists of baked shales and limestones, 

which overlap the lower zones on to the Cambrian limestone. Specimens 

of Arnioceras abound at several levels. Near the base are Gryphcea beds, 

so intensely baked by igneous intrusions that the shells have been reduced to 

the semblance of small clinkers lying within perfect moulds left in the baked 

shale or limestone. Both here and round the Suisnish promontory on Loch 

Eishort the zone forms cliffs of considerable height.

120 THE LIAS 

BUCKLANDI, ANGULATUM ZONES. East of Broadford, the bucklandi zone 

consists chiefly of sandstones, which crop out on the shore as reefs along the 

low promontory of Ardnish. Here Coroniceras occurs, and other conspicuous 

fossils are Gryphcea cf. arcuata and Lima gigantea. 

The tidal inlet of Ob Breakish separates these sandstones from a limestone 

series representing the angulatum and underlying zones. These last form reefs 

and broad pavements often weathered into remarkable shapes. The most 

interesting feature is the Ob Breakish Coral Bed, a prominent bed with 

Thecosmilia martini at the base, associated with several bands of limestone 

containing corals. This bed has been traced for a considerable distance 

inland. At Applecross the same coral abounds in a 4 ft. band of limestone, and 

it is in places so abundant as to resemble a reef. At Applecross there are only 

30-40 ft. of Lias below the coral bed, but at Ob Breakish there are 60-70 ft., 

probably owing to the intercalation of beds belonging to the planorbis zone. 

The same coral bed is also found at Loch Sligachan. 

In Raasay and at Applecross ammonites have been collected more carefully 

than in Skye, and the result has been to show that the exact line of demarcation 

between the bucklandi and angulatum zones in the Hebrides still remains 

to be drawn. As in Skye, the bucklandi zone is predominantly arenaceous while 

the angulatum zone consists of limestones, but the fossil evidence is scanty. In 

Raasay the semicostatum zone is underlain by 90 ft. of calcareous sandstone 

and sandy shale which definitely belongs to the bucklandi zone; it has yielded 

Coroniceras bucklandi 25 ft. from the top and Metophioceras cf. conybeari 40 ft. 

from the top, while in fallen blocks below, Paracoroniceras gmuendense 

has been found. Below this, 50 ft. of sandy shale and brown sandy limestone, 

yielding only Gryphcea cf. arcuata, l pass down insensibly into 140 ft. of 

almost unfossiliferous limestones, sometimes sandy, with shaly partings. At 

Applecross a specimen of Scamnoceras cf. montanum (Wahner) has been 

found a few feet above the presumed equivalent of the Ob Breakish Coral 

Bed. 

PLANORBIS ZONE. From Ob Breakish to Lusa, at the end of the Lias outcrop 

east of Broadford, the shore reefs show a series of hard, compact limestones 

and calcareous sandstones, probably 30-50 ft. thick. They are still palaeontologically 

unclassified, but they may ultimately prove to represent iht planorbis 

zone. About 6-8 ft. from the base is a second coral bed, the Lusa Coral Bed, 

composed of Isastrcea. It too can be traced for some distance inland, where it 

is well displayed in a quarry west of the cross-roads on the Kylerhea road; 

unlike the Thecosmilian coral bed of Ob Breakish, it is not represented at 

Applecross. Its position may be either in the planorbis zone or in the Preplanorbis 

Beds. 

PRE-PLANORBIS BEDS. In the basement portions of the Lower Lias east of 

Broadford and elsewhere in Skye definite indications of deposits on the horizon 

of the Pre-planorbis Beds are lacking. This may be due to the beginning of 

the overlap of the higher zones towards the south, which culminates in the 

absence of all the zones below that of Arnioceras semicostatum on the shore of 

1 The Grvphaeas of this lower part of the Broadford Beds are seldom more than 1J in. in 

height, and differ from G. arcuata also in their greater breadth and ill-defined sulcus. For 

comparisons see G. W. Lee, 1925, loc. cit., pp. 12-16.


Loch Slapin. Farther north, on the island of Raasay, and still more on the 

mainland at Applecross, Pre-planorbis Beds with their usual characters are 

well developed. 

At Applecross the basement beds of the Lias are best exposed in a streambank 

and limekiln, described in detail by Lee, § mile south-east of Applecross 

House. Here the sandy marls of the Trias are succeeded by calcareous sandstone 

and limestone, in which Ostrea liassica abounds at certain levels up to 

30 ft. from the base. From 20 to 30 ft. from the base are bands of oolitic 

limestone crowded with the oysters, which can be collected in a perfect state 

of preservation, equalling anything to be found in England. The top of this 

oolite is only 10 ft. below the presumed equivalent of the Ob Breakish Coral 

Bed, and close beneath the horizon at which Scamnoceras montanum was 

found, leaving but little room for the planorbis zone. 

(b) Mull, Morven and Ardnamurchan. 

Isolated areas of Lower Lias occur at a number of points around the coasts 

of Mull, north, east, south, and west; at Loch Aline in Morven; and on both 

the north and the south coasts of the peninsula of Ardnamurchan (map, p. 114). 

Some of these occurrences have been known from the earliest times and were 

described in detail by Judd, but a flood of new information concerning them 

has recently become available through the work of the Geological Survey of 

Scotland. 

The general succession is the same as in the more northerly islands, although 

the total thickness is only about half that in the north. Except in Morven 

there is the same broad division into Pabba Shales (about 400 ft.) and Broadford 

Beds (70-100 ft.) There are several features of special interest, chief 

among which are local and richly fossiliferous occurrences of the ibex zone at 

Tobermory, and of the planorbis zone and Pre-planorbis Beds at Gribun in 

Western Mull, and a thick development of the obtusum zone at Loch Aline in 

Morven. 

The fullest development is probably displayed by the sections in Ardnamurchan, 

where the Broadford Beds reach their maximum thickness of 100 ft. 

near Swordle, on the north coast, and are also well seen on the south coast near 

Mingary Castle. But the Pabba Shales, although well exposed on the south 

coast, in the west side of Kilchoan Bay, are almost completely unfossiliferous; 

the Survey found only one ammonite of doubtful identity. This is difficult to 

account for, since the amount of baking to which the shales have been subjected 

would not have been sufficient to destroy fossils had any been present. 

The Broadford Beds consist mainly, as in Mull and Morven, of limestones 

crowded with Gryphcea arcuata, and they are no less fossiliferous than elsewhere. 

The fullest particulars of the zonal constitution of the Lower Lias in this 

district have been obtained from the south-east coast of Mull. Grand displays 

of the formation may be seen in the cliffs of the peninsulas between Loch 

Buie, Loch Spelve and Loch Don, and again in Duart Bay, and farther 

west in the Carsaig district. More remote fragments exposed at Gribun 

in the west and at Tobermory in the north of the island each have a special 

feature of interest not met with in the larger areas.

120 

THE LIAS 

SUMMARY OF THE LOWER LIAS IN MULL, MORVEN AND ARDNAMURCHAN 1 

Davoei ?, Ibex, Jamesoni, and Raricostatum Zones (PABBA SHALES), 

400 ft. 

As in the northern islands, the Pabba Shales denote remarkable uniformity 

of sedimentation—excepting only that they become increasingly sandy towards 

the top, and that this gradual increase in the proportion of sandy sediment sets 

in earlier in some places than in others. In the coast-sections north-east of 

Torosay Castle, Duart Bay, the sandstone facies extends to the bottom of the 

division. There not only is the major part of the Pabba Shales sandy but they 

pass down into 50 ft. of greenish fine-grained flaggy sandstone, resting directly 

on the Broadford Beds. In short distances, as on the other side of Duart Bay, 

they become more argillaceous. 

The upper part of the Pabba Shales is well exposed in the long stretch of 

cliffs between Loch Don and Loch Buie, and again, with the downward continuation, 

in broad tidal flats on both sides of Carsaig Bay. Sandy shale and 

ferruginous shaly sandstone alternate down through the davoei and jamesoni 

zones into the top of the raricostatum zone (olim armatus zone). Ammonites 

are exceedingly rare, but enough have been found in fragmentary condition for 

approximate dating. In the uppermost 100 ft. Gryphcea cymbium and Pseudopecten 

cequivalvis abound, thus ushering in the Middle Lias conditions before 

their time, as in Raasay and Skye and in Yorkshire. On the tidal flats of 

Carsaig Bay ammonites are less rare than farther east. This is the type-locality 

of Uptonia jamesoni (Sow.), and large specimens of U. bronni (Roem.) can still 

be collected in fair abundance on the west side of the bay. On the east side the 

sandy micaceous shales, although much the same as those on the west, are on 

a lower horizon, and in them many small black nodules harbour over a dozen 

species of Echioceras. This is the only locality in the southern part of the 

Hebridean area where a glimpse is to be obtained of the rich Echioceras fauna 

of Raasay. 

A single ammonite found at Port Donain gave the only indication of the 

davoei zone in the Southern Hebridean area, although there are many exposures 

of the top of the Pabba Shales. None of these localities has yielded any 

evidence of the ibex zone, except a small and isolated patch of Lower Lias at 

the north end of the island of Mull, near Tobermory. The Tobermory River 

has cut a small section of the Pabba Shales, and in the bed of the stream and 

beside a path along the left bank have been found large numbers of crushed 

and badly preserved fossils, chief among which are some five species of the 

genus Tragophylloceras. 2 

Obtusum Zone (LOCH ALINE SANDSTONE), 0-160 ft. (Morven only.) 

The highest Jurassic beds preserved in Morven consist of a remarkable mass 

of shaly sandstone passing down into sandy shale, the LOCH ALINE SANDSTONE. 

On both sides of Loch Aline it is a conspicuous feature, reaching as much as 

160 ft. in maximum thickness, but towards the head of the loch it has been 

1 Based on G. W. Lee, 1925, 'Pre-Tert. Geol. Mull, Loch Aline and Oban', pp. 75-91; 

G. W. Lee, E. B. Bailey and J. E. Richey, 1930, in 'Geol. Ardnamurchan', pp. 36-42, Mems. 

Geol. Surv. 

2 Judd mistook them for Oxynoticeras, thus wrongly recording the oxynotum zone—G. W. 

Lee, 1925, loc. cit., p. 89.


cut off by erosion preceding the Cenomanian transgression and disappears 

altogether. Fossils are rare, but the Survey obtained an assemblage indicating 

that the whole of the Loch Aline Sandstone belongs to the obtusum zone: 

namely Asteroceras suevicum? (Quenst.), Xipheroceras aureum (Y. and B.), 

Xiph. cf. planicosta (Sow.) and Coroniceras sp. (bucklandi Reynes non Sow.). 

Lee remarked that, in spite of the apparent localization of this fauna to Morven, 

'it would be difficult to believe that the obtusus zone is really unrepresented 

in Mull' 1 and this view receives support from Dr. Spath's discovery of the 

obtusum fauna at Mingary Castle in Ardnamurchan. 2 If it is represented in 

Mull, it is probably to be sought among the lower arenaceous shaly beds 

classed for convenience with the Pabba Shales (compare especially the 50 ft. of 

shaly sandstone immediately overlying the Gryphcea limestones of the semicostatum 

zone north-east of Torosay Castle, above, p. 148). It was probably 

largely in view of this possibility that the Survey in their memoir of 1925 

departed from the original classification founded in Skye and included the 

obtusum zone in the Pabba Shales. In the more recent memoir dealing with 

Ardnamurchan (1930) the Survey have reverted to the original classification 

and returned the obtusum zone to the Broadford Beds. But in the area covered 

by the 1930 memoir they did not have to deal with the difficulties with which 

Lee was confronted in south-east Mull and Morven. Since the Loch Aline 

Sandstone does not accommodate itself naturally within either the Pabba 

Shales or the Broadford Beds, and is unknown in the type-area of both, it 

seems advisable to keep it separate. 

Semicostatum, Bucklandi, Angulatum, Planorbis and Pre-planorbis 

Zones (BROADFORD BEDS), 70-100 ft. 

The Broadford Beds, which do not reach a third of their thickness in Raasay, 

consist chiefly of limestones crowded at many levels with Gryphcea arcuata, 

and alternating with beds and partings of shale. The Gryphaeas show a steady 

enlargement as they are traced upward through the series, and at the same 

time the shells grow more elongate and more sulcate. The average size in the 

lower levels falls short of 1 in. in length, and few exceed 1J in.; at the top the 

length (height) commonly reaches 3 in. Ammonites are always rare, but such 

as have been found show that the Gryphcea Limestones correspond with the 

semicostatum and bucklandi zones. 

The lower zones of the Broadford Beds are exceptionally barren in the 

principal sections. In all the exposures in South and South-East Mull and 

Ardnamurchan (they are not exposed in Morven) the lowest 20-30 ft. of the 

Lias consists of almost unfossiliferous limestones, which cannot be zonally 

classified. On the south coast of Ardnamurchan the Survey infer the presence 

of the angulatum and planorbis zones from certain accessory fossils, but no 

ammonites have been found. 

Only in Western Mull, on the coast of the Wilderness, south of Gribun, do 

the basal beds contain the representative faunas met with in England. Here 

a small isolated patch of the basement beds of the Lower Lias yields the only 

representative of the planorbis fauna known in Scotland, as well as typical 

Pre-planorbis Beds crowded with Ostrea liassica as at Applecross. Since these 

1 G. W. Lee, 1925, loc. cit., p. 86. 

2 L. F. Spath, 1922, Geol. Magvol. lix, p. 172.

120 THE LIAS 

rest upon the best example of the Rhaetic Beds known in Scotland, the interest 

of the locality is exceptional. 

Thz planorbis zone comprises 20 ft. of dark shale with bands of limestone, 

and from it the Survey collected Psiloceras planorbis (Sow.), P. erugatum 

(Bean-Phil.), P. sampsoni (Portlock) and P. hagenowii (Quenst.), with a rich 

fauna of lamellibranchs of the typical genera and species. Below are 8 ft. of 

sandy limestone and calcareous shale, crowded with O. liassica, and at the base 

of all 19 ft. of micaceous and calcareous sandstone devoid of all fossils but 

plant-remains. 

X. E A S T E R N S C O T L A N D 1 

There is a small area of Lower Lias in East Sutherland, near Dunrobin, 

Golspie (map, fig. 28), but it is deeply covered by Drift and the only exposure 

is on a short stretch of foreshore between tidemarks, immediately east of the 

grounds of Dunrobin Castle. The total thickness visible is some 60 ft., within 

which are many gaps, and although long lists of fossils have been published, 

the ammonites are not wholly satisfactory for diagnosis. Definite indications 

of the davoei, ibex and raricostatum zones have, however, been found, in the 

form of ammonites identified by Buckman as Prodactylioceras aff. davoei, 

Coeloceras aff. pettos and Apoderoceras leckenbyi. All these forms occurred 

in one bed 6 ft. 9 in. from the top of the exposed sequence, whereas in Pabba 

Island the first and last are separated by at least 100 ft. of shales. The lastnamed 

characterizes a level now usually considered as the highest subzone 

of the raricostatum zone. There is therefore a considerable condensation at 

Dunrobin. 

Some 20 ft. lower down another fossiliferous bed has yielded ill-preserved 

ammonites suggestive of the raricostatum zone, but they are not fit for identification 

with absolute certainty. 

Lithologically the strata are very varied, comprising clays and shales with 

bands of limestone and micaceous sandstone. 

IX. K E N T 2 

The numerous borings in Kent have proved that the Lias is overlapped 

towards the north and north-east by the succeeding members of the Jurassic 

System. Its northern boundary underground is approximately coincident 

with the main line of railway from Dover to Canterbury and probably onward 

to Faversham and Chatham. South of this line all the borings have proved the 

presence of the Lias, but north of it the Lower Oolites overlap on to the rising 

Palaeozoic floor before being in turn overstepped by the Cretaceous. 

The Lower Lias is represented only by the highest portions, no evidence 

having been obtained in any boring for the presence of beds lower down in the 

sequence than the ibex or jamesoni zones, while in the most northerly and 

north-easterly borings these also are overlapped and the davoei zone alone is 

present. The thickness diminishes steadily northward and north-eastward, 

from 80 ft. at Brabourne and 40 ft. at Folkestone to such small amounts as 

4 ft. at Chilton and Fredville, 3^- ft. at Harmansole, and 2 ft. at Bishopsbourne. 

1 G. W. Lee, 1925, in 'Geol. Golspie', Mem. Geol. Surv.y pp. 69-74. 

2 Based on G. W. Lamplugh and L. F. Kitchin, 1911, 'Mes. Rocks, Coal Expl. Kent'; and 

Lamplugh, Kitchin, and Pringle, 1923, 'Concealed Mes. Rocks Kent', Mems. Geol. Surv.

LOWER LIAS: KENT 151 

The typical lithological constituent of the Lower Lias is a grey shaly clay, 

often shelly along the bedding-planes, with some thin bands of limestone. At 

the base there are frequently small well-rounded pebbles derived from the 

underlying Palaeozoic sandstones, and sometimes the 'junction suggests that 

the Liassic basement-bed filled up minor irregularities in the worn surface'. 1 

At Chilton the basement-bed was a thin limestone band containing corals, 

1 1923, loc. cit., p. 82.

152 THE LIAS 

apparently Montlivaltiay some of which showed definite signs of rolling and 

had been drilled by boring mollusca. 

The greater part of the Kentish Lower Lias belongs to the davoei zone, 

which is about 60 ft. thick at Brabourne, in the south-west, and has the widest 

extension of all the zones to the north and north-east. Its fossiliferous grey 

clays have yielded Androgynoceras maculatum (Young and Bird), A. cf. 

latcecosta (Sow.) and Oistoceras arcigerens (Phil.), while among bivalves the 

genera Nuculana, Astarte and Parallelodon are numerous. 

In the south-westerly borings, where earlier beds are preserved, they are 

relatively thin. At Brabourne and Elham the davoei grey clays were found to 

be separated from the Palaeozoic platform by a few feet of ferruginous marls, 

some of the layers ironshot. These lowest ironshot beds yielded no ammonites, 

but at Brabourne and again at Dover Rimirhynchia and Lima antiquata 

Sow. were found, while immediately above them an ammonite assigned 

by Buckman tentatively to the valdani hemera would seem to indicate the 

base of the ibex zone. The ironshot marls are therefore believed to represent 

the upper part of the jamesoni zone, if not earlier beds.

PLATE V 

Photo. Purch. 

Golden Cap (619 ft.) from Seatown. 

The three white lines mark the position of the Three Tiers. The capping 

(giving the cliff its name) is Upper Greensand. 

Photo. Purch. 

Down Cliff and Thorncombe Beacon from Eypesmouth. 

The nearest cliff on the right is of Middle Lias. The Down Cliff Clay caps 

the two farthest cliffs, and above it follow some Bridport Sands and Upper 

Greensand on Thorncombe Beacon (in the centre).

CHAPTER VI 

MIDDLE LIAS 

Stage. Zones (Faunizones). Thickness. Dorset Coast Strata. ! 

domerian or 

upper pliensbachian 

Paltopleuroceras 

spinatum 

Amaltheus 

margaritatus 

8" Marlstone 

35 -75' 

Thorncombe Sands 1 

1' Margaritatus Bed 

75' 

4*' 

155' 

25-35' 

Down Cliff Sands 1 or 

Laminated Beds ! 

Starfish Bed 

Micaceous Beds 

The Three Tiers 

I. DORSET COAST TO THE MENDIPS 

THE Middle Lias of the Dorset coast begins with a prominent basal 

division called the Three Tiers. These consist of three thick bands of 

brown, fissile, micaceous and calcareous sandstone, separated by layers of 

micaceous sandy clay, the whole forming a prominent tripartite ledge 35 ft. 

thick. The Three Tiers first appear beneath the Greensand capping of Stonebarrow 

and Westhay Cliffs, east of Charmouth, and fall gently eastward, until 

they run down to within 80 ft. of the beach under Golden Cap at Seatown, 

where they are faulted out of sight (fig. 20, p. 119, and Plate V). 

The greater part of Golden Cap, excepting the lowest 80 ft., is formed of 

precipices of Middle Lias marls and sands rising above the Three Tiers, and 

contrasting sharply with the dark Lower Lias below. The cliff, which is the 

highest on the South Coast and provides the finest Lias section in England, 

rising to 619 ft. above the sea, derives its name from a capping of yellow Albian 

sands. 

East of Seatown the Middle Lias forms the greater part of Down Cliffs and 

the lower precipice of Thorncombe Beacon, thinning eastwards, and finally 

ending at another fault on the east side of Eypesmouth (fig. 29, p. 154). 

The maximum thickness of the Middle Lias in these cliffs is 345 ft., or only 

just over 100 ft. less than that of the Lower Lias. But palaeontologically it is 

incomparably poorer, for in contrast to the uniform clays of the Lower Lias, 

with their scores of ammonite horizons, the more varied succession of the 

Middle Lias lends itself readily to division into only two zones. 

SUMMARY OF THE MIDDLE LIAS OF THE DORSET COAST 2 

Spinatum Zone (MARLSTONE AND THORNCOMBE SANDS), 35-75 ft. 

At the top is a highly fossiliferous band of limestone called the Junction Bed, 

5 ft. thick, crowded with ammonites. Four-fifths of the Junction Bed belong 

1 Named by Buckman, 1922, Q.J.G.S., vol. lxxviii, p. 382. The other names are those used 

by the Survey many years before. 

2 H. B. Woodward, 1911, 'Geol. Sidmouth and Lyme Regis', 2nd ed., Mem. Geol. Surv., 

pp. 40-1; and 1893, J.R.B., pp. 195-201; S. S. Buckman, 1922, Q.J.G.S., vol. lxxviii, pp. 

395-400.

SEATOWN 

BRIDPORT 

HARBOUR 

EAST 

CLIFF 

DOWN 

CLIFF 

RIVER 

BRI DE 

THORNCOMBE 

BEACON (509') 

BURTON 

CLIFF 

E YPE 

BURTON 

VILLAS 

WAT TON 

CLIFF 

CLIFF END 

rr BRIDPORT 

h SAND 

BRIDPORT 

HAKBOUR 

BURTON 

MERE 

FIG. 29. Section along the cliffs from Seatown to Bridport Harbour and Burton Bradstock. Total distance 5$ miles. Vertical scale exaggerated. 

The upper section based on H. B. Woodward, 1893yJ.R.B.y p. 52, fig. 41, with amendments.

MIDDLE LIAS: DORSET COAST 155 

to the Upper Lias and will be dealt with in the next chapter, but the lowest 

8 in. form a representative of what is known inland as the MARLSTONE. This 

is itself divisible into two seams, the upper a fine-grained and richly fossiliferous 

limestone, the lower brown or greenish-grey, iron-shot and conglomeratic, 

poor in fossils on the coast, but yielding Tetrarhynchia tetrahedra a 

short distance inland. Beneath come 75 ft. (thinning to 60 ft. under Thorncombe 

Beacon and 35 ft. in Watton Cliff, east of Eype) of light brown and 

yellow sands, argillaceous at top and bottom, with huge doggers about the 

central portion. Buckman named them the THORNCOMBE SANDS. They 

yield Tetrarhynchia thorncombiensis and ammonites formerly identified as 

'A. spinatus\ but Buckman suggested these might be species of Amaltheus. l 

Margaritatus Zone, 270 ft. 

The top of this zone is marked by the MARGARITATUS BED, 1 ft. thick, a hard 

blue and brown, ferruginous, sandy limestone, yielding Amaltheus spp. 

abundantly, together with T. ? tetrahedra, Pseudopecten cequivalvis, Gryphcea 

cymbium, Cerithium liassicum Moore, Cryptcenia cf. solarioides (Sow.), Ataphrus 

cinctus Moore, belemnites, and other less certainly identified fossils. It forms 

an easily recognized capping to the 

LAMINATED BEDS or DOWN CLIFF SANDS: about 75 ft. of micaceous and 

ferruginous sandy clays and marls with nodules and bands of hard fissile 

sandstone, poor in fossils, but containing some nests of small cuboidal 

Rhynchonellids, small Amaltheids, Gryphcea cymbium, Pseudopecten cequivalvis 

and a few other lamellibranchs. A marked layer below the Laminated Beds is 

formed by the Starfish Bed, 4 ft. 6 in. of hard greenish-grey micaceous and 

calcareous sandstone with an irregular and hummocky upper surface, noteworthy 

for containing the starfish Ophioderma egertoni and O. tenuibrachiata. 

The 155 ft. between the Starfish Bed and the Three Tiers are occupied by 

monotonous, bluish-grey, micaceous marl and clay, known as the 

MICACEOUS BEDS. They contain nodules of ironstone, iron pyrites, and 

grey earthy limestone; Amaltheus aff. clevelandicus, A. cf. boscensis, and 

Nuculana graphica are recorded from them. The base is formed by the Three 

Tiers, already described—three bands of sandstone ft. thick, separated by 

two 10 ft. bands of clay. They have yielded ammonites recorded as 4 A. margaritatus', 

4 A. fimbriatus' and ( A. loscombei' (the last derived?), and bones of 

Saurians. 

Inland through Dorset and West Somerset 2 the Middle Lias is little known 

owing to the lack of exposures, but in two or three places the Marlstone is 

seen, still welded to the under-surface of the Junction Bed. The Three Tiers 

disappear a short distance from the coast, so that the mapping of the boundary 

between Lower and Middle Lias in Dorset and Somerset is uncertain, but 

there are always signs of a considerable thickness of evident Middle Lias. 

In the Ilminster district are 50 ft. of sands with ironstone nodules, passing 

down into yellow micaceous marls with sandstones, below which are 100 ft. of 

blue and grey micaceous marls. 

1 S. S. Buckman, 1922, loc. cit., p. 396; stratal names on p. 382. 

2 H. B. Woodward, 1893,7. R- B., pp. 202-8.

120 THE LIAS 

Although the main mass of the beds here attains only half of the thickness 

on the coast, the Marlstone has thickened to 12 ft. It consists of irregular beds 

of rusty ironshot limestone, sometimes sandy and micaceous. Long lists of 

fossils were recorded by Charles Moore, but they are in need of revision. They 

include P. spinatum, Pseudopecten cequivalvis, Gryphcea cymbium, T. tetrahedra, 

and other brachiopods, with Ichthyosaurus, Hybodus, Lepidotus, gastropods, 

echinoderms, crustacea, sponges, foraminifera and plant-remains. 1 Northward 

and eastward along the outcrop the Marlstone thins again to 7 ft. at 

Barrington and 3! ft. at S. Petherton, until at Yeovil it has a thickness of only 

1 ft. 3 in. once more. From there northward the whole Middle Lias thins out 

steadily towards the Mendip Axis, so that in about 15 miles, before Shepton 

Mallet is reached, it has disappeared completely. 

Along this diminishing outcrop in North Somerset little is seen of the beds, 

but such exposures as exist show nothing abnormal. They have been worked 

for bricks on the outliers of Glastonbury and Pennard, where the Marlstone 

is 1 ft. thick. The farthest outlier forms Brent Knoll, close to the shore of 

the Bristol Channel, 23 miles from the main outcrop. 

II. THE MENDIP AXIS AND DUNDRY HILL 

Over the centre of the Mendip Axis, about Nunney and Vallis Vale, south 

of the Wellow Valley, the Middle Lias is absent, but fossils derived from it are 

found mixed with others from the Lower and Upper Lias in pipes in the 

Carboniferous Limestone. Close to the axis on either side, however, the Marlstone 

is present and unusually thick. 

On the south side, at Batcombe and Maes Down, Evercreech, on the main 

outcrop between Bruton and Shepton Mallet, where the Middle Lias is too 

thin to appear on the Geological Survey maps, all the strata below the Marlstone 

are missing, but the Marlstone itself is from 5 ft. to 10 ft. thick. It is 

a hard, dark, ironshot limestone, and has yielded P. spinatum, Lobothyris 

punctata, Tetrarhynchia tetrahedra, Ornithella indent at a, Pseudopecten cequivalvis, 

and a number of other fossils. 2 

Similarly, on the north side of the axis, it was proved in a boring at Mells 

to be 9 ft. thick and to rest on Coal Measures. 3 

At the base of the outlier of Dundry Hill, 10 miles west of Bath, the Marlstone 

takes the form of an impersistent, coarse, yellowish-brown ironshot 

limestone, usually oolitic, more especially in the upper part, and yielding 

Pseudopecten cequivalvis, &c. The maximum thickness is 3 ft. It rests upon 

clays, the age of which has not been determined 4 (see fig. 34, p. 196). 

In the Radstock district the Middle Lias is again absent altogether, and the 

Upper Inferior Oolite, sometimes with Upper Lias of very variable thickness 

intervening, comes to rest on an eroded surface of different horizons in the 

Lower Lias. These conditions seem to continue as far as Bath, and also down 

the dip-slope to the east, for Middle Lias was proved to be absent in the 

Westbury boring. 

1 C. Moore, 1853, Proc. Somerset Arch. Soc., vol. iii, pp. 61-76; and 1867, ibid., vol. xiii, 

pp.119-244. 

2 L. Richardson, 1906, Geol. Mag. [5], vol. iii, pp. 368-9; and 1909, ibid., vol. vi, pp. 540-2. 

3 C. Moore, 1867, loc. cit., p. 150. 

« S. S. Buckman and E. Wilson, 1896, Q.J.G.S., vol. Iii, pp. 686, 705-6.

M I D D L E LIAS: C O T S W O L D S A N D M I D L A N D S 157 

III. T H E C O T S W O L D HILLS 

North of Bath, on the main outcrop, the Middle Lias gradually returns, 

thickening northward until it reaches 100 ft. at Wotton under Edge, 150 ft. 

at Frocester Hill near Stroud, and about 250 ft. in the Mid-Cotswolds. The 

Marlstone is usually from 10 ft. to 15 ft. thick and forms a fairly conspicuous 

platform running along the foot of the Cotswold escarpment. 1 It also extends 

on to a number of outliers, of which the most important are Church Down, 

Alderton, Dumbleton, and Bredon Hills. 2 It is generally an arenaceous limestone, 

locally ferruginous, but never sufficiently so to merit working as an iron 

ore. Here and there it is used as a building stone. 

The Marlstone of the Cotswolds contains Paltopleuroceras spinatum in its 

upper part and Amaltheus margaritatus in its lower part. 3 It therefore spans 

a considerable thickness of strata on the Dorset coast. 

The lower part of the margaritatus zone, consisting of sands and micaceous 

shales, is poorly fossiliferous. They are best exposed in a brickyard at Wotton 

under Edge, where, although seen to a depth of 30 ft., they have yielded no 

fossils. 

IV. T H E V A L E OF M O R E T O N AXIS A N D OXFORDSHIRE 

East of the Mid-Cotswolds the Middle Lias thins rapidly towards the Vale 

of Moreton. In the deep boring at Burford it was proved to be only 100 ft. 

thick, but the greatest reduction takes place farther east, in the Evenlode 

Valley, where at Fawler it probably does not exceed 30 ft. 4 The Marlstone 

has a thickness of about 10 ft. and overlies 11 ft. of sands with a blue clay 

below, the upper part of which is said to yield Amaltheus margaritatus 5 and 

the lower part Androgynoceras capricornum at no great depth. 

V. T H E M I D L A N D I R O N S T O N E DISTRICTS 

In the Midlands the Marlstone has been extensively worked as an iron ore 

in two districts, the first about Banbury, in North Oxfordshire, the second 

between Wartnaby and Grantham, in Leicestershire and South Lincolnshire. 

It forms an almost continuous band, giving rise from Edge Hill north-eastward 

to a broken escarpment overlooking the Midland Plain and the Vale of 

Belvoir. 

On the Edge Hill plateau, where it rises to 700 ft. above sea-level, the Marlstone 

is a rock band 25 ft. thick, consisting of rusty sandstones, all of which 

are quarried for road-mending and building. Eastward it thins to 10-12 ft. in 

the Banbury ironstone district about the Cherwell Valley; to 6 ft. and less in 

Northamptonshire; and eventually to less than 1 ft. between Keythorpe and 

Hallaton, 7 miles east-north-east of Market Harborough, approximately on 

the line of the Charnwood Axis. Here the greater part seems to have been 

1 L. Richardson, 1904, Handbook Geol. Cheltenham, pp. 47-52. 

2 In old exposures on Church Down the Middle Lias was minutely studied by F. Smithe 

and at Alderton by F. Smithe and W. C. Lucy; see bibliography. 

3 For revised list of fossils and many details of the Cotswold district see L. Richardson, 

1929, 'Geol. Moreton in Marsh', pp. 23-7, Mem. Geol. Surv. 

4 F. A. Bather, 1886, Q.J.G.S., vol. xlii, p. 144. 

5 Prof. Trueman informs me that it is doubtful if this identification is correct, and that the 

species is probably A. maculatum.

120 THE LIAS 

removed by erosion prior to the deposition of the Upper Lias, and the surviving 

relic is locally decalcified and impersistent. 1 It may be only coincidence, but 

it is certainly noteworthy that the Marlstone ceases to be a workable ore just 

before it approaches the Nuneaton Axis (about 4 miles south of Daventry), 

and is not again exploited until Tilton in Leicestershire, which is a few miles 

beyond the Charnwood Axis. The working at Tilton is an isolated one; the 

main iron-field lies north of Melton Mowbray, occupying the long spur of 

Middle and Upper Lias and oolites that protrudes westward to Wartnaby, 

and embracing the main outcrop thence for 25 miles northward to Leadenham 

in Lincolnshire. 

In this Leicester-South Lines, iron-field the Marlstone is 35 ft. and in 

places even 40 ft. thick. Only from 9 ft. to 16 ft. at the top, however, yield the 

ore, the lower part consisting of about 25 ft. of calcareous sandstones as at 

Edge Hill. The ore gives out altogether at Leadenham, 14 miles south of 

Lincoln, leaving only the sandstone; at first about 7 ft. thick, this diminishes 

to 5 ft. between Lincoln and the Humber. 

The best Marlstone ore, when unweathered, is a green, densely oolitic 

limestone, with dark green ooliths set in a darker matrix. It yields from 23 to 

about 28 per cent, of iron. The poorer varieties are lighter in colour, less 

densely oolitic, and contain calcite and clusters of the brachiopods Tetrarhynchia 

tetrahedra and Lobothyris punctata and other shells. The iron occurs 

mainly in the form of carbonate, with some silicate. Surface solution and 

oxidation have partly converted the ore into a soft brown, decalcified oolite, 

in which both ooliths and matrix consist of ferric oxide. It is in this form that 

it is usually quarried, at or near the surface, for the natural agencies of surface 

weathering have enriched the ore by decalcification. Under a thick protective 

covering of Upper Lias clays it is not worth working. 2 

Palaeontologically the Marlstone is characterized, as in the counties farther 

south, by the two brachiopods just mentioned, and by the molluscs Passaloteuthis 

elongatus (Miller), Pseudopecten cequivalvis (Sow.), Chlamys liasianus 

(Nyst.), Oxytoma incequivalvis (Sow.), Modiola scalprum (Sow.) and Protocardia 

truncata (Sow.). The zonal ammonite, Paltopleuroceras spinatum, is 

rare. 

The margaritatus zone thickens rapidly east of the Evenlode Valley, reaching 

its maximum, 120 ft., in Leicestershire, and then diminishing towards the 

Humber. At Grantham it is 55 ft. thick and at Lincoln it has dwindled to 

30 ft. In the southern part of the area, in North Oxfordshire and Northants, 

it consists of sandy, micaceous, blue and brown clays with bands of sandy, 

fissile limestone at intervals, and occasional layers of cementstone nodules. In 

the northern part of the outcrop, in Leicestershire and Lincolnshire, the 

series is, on the whole, rather more argillaceous and in the absence of Amaltheids 

it is often difficult to distinguish from the Lower Lias. 

Locally, in Northamptonshire, the lower boundary is defined by a layer of 

water-rolled fossils and pebbles, bored, and coated with Serpidce or Polyzoa. 

In this layer are found Pseudopecten cequivalvis and Plicatula Icevigata and in 

places there is a green sand largely composed of foraminifera. 

1 J. W. Judd, 1875, 'Geol. Rutland', Menu Geol Surv., p. 64. 

2 C. B. Wedd, and J. Pringle, 1920, 'Spec. Repts. Min. Resources', vol. xii, pp. 106-140; 

Mem. Geol Surv.

M I D D L E LIAS: SHROPSHIRE 159 

A mottled rock-band, similarly containing pebbles, rolled fossils and comminuted 

shells, occurs also in Northamptonshire in the upper half of the 

margaritatus zone. Most of the other rock-bands contain Protocardia truncata 

more or less abundantly, while one immediately underlying the Marlstone 

near Daventry Railway Station is almost composed of the shells of Cardinia 

listeri, C. crassissimay C. crassiuscula, C. Icevis, C. concinna, and gastropods. 1 

Va. The Shropshire Outlier 2 

Interesting evidence of the north-westward extension of the Middle Lias 

sea is afforded by a Marlstone capping to the Lower Lias outlier at Prees, in 

Shropshire. The lithological and palaeontological facies on this distant outlier 

are the same as in the main outcrop, from which it is separated at the nearest 

point (due west) in Leicestershire by 68 miles. 

The Marlstone is known only from graves in Prees churchyard, but it has 

a thickness of 8-10 ft. and has yielded Paltopleuroceras spinatum and all the 

usual fossils. The underlying micaceous and sandy beds and clays, with 

Amaltheus margaritatus, were formerly w r orked in an old brickyard and have 

been seen in various small exposures to 20 ft., but their total thickness is 

unknown. 

VI. T H E M A R K E T W E I G H T O N AXIS 3 

The gradual diminution in thickness of the Middle Lias through Lincolnshire 

is continued beneath the Humber. On its first appearance in Yorkshire, 

where it was pierced in a boring at Brantingham Grange, near South Cave, the 

total thickness is not more than 16-J- ft. Three miles farther north, in Everthorpe 

railway-cutting, it has shrunk to 9 ft., and for another 6 miles, as far 

as Market Weighton, it is just capable of being mapped as a separate formation. 

There is here no definite division into Marlstone and margaritatus beds, the 

whole consisting of shales with several thin ferruginous limestone bands at 

various levels, some of them grey and crystalline. Paltopleuroceras spinatum 

and most of the usual Marlstone fauna have been recorded from several 

localities, immediately underlain in Everthorpe cutting by Lower Lias with 

Androgynoceras capricornum; from which it appears that the margaritatus zone 

is missing. 

From Sancton (2 miles south of Market Weighton) onward for 7 miles the 

Middle Lias is directly overlain by the Cretaceous. It is everywhere too thin 

to be mapped, and, after becoming traceable only by occasional patches of 

ferruginous rubble, it eventually disappears altogether, leaving Cretaceous 

rocks for about 5 miles resting directly on Lower Lias. 

Between the last trace of Middle Lias on the south of the axis and the first 

point at which it has been detected on the north is a gap of 8 miles. On the 

north side definite evidence of Upper Lias is obtainable 3 miles earlier than 

the first signs of Middle Lias. This proves that the Middle Lias thins out 

altogether against the axis, and that its absence is not due to removal prior 

to the deposition of the Chalk. 

1 B. Thompson, 1889, The Middle 

pp.458-61. 

Lias of Northamptonshire; and 1910, Geol. in the Field, 

2 H. B. Woodward, 1893, J.R.B., pp. 243-4. 

3 C. Fox-Strangways, 1892,7/^-6., PP- 120-2.

120 

THE LIAS 

VII. T H E YORKSHIRE BASIN (CLEVELAND I R O N S T O N E DISTRICT) 1 

Across the Dement thickening sets in rapidly, and along the southern 

side of the Howardian Hills and in the faulted tracts about Easingwold a 

Middle Lias terrace-feature is traceable once more. The thickness increases 

from 30 ft. near the Derwent to 70 ft. about the Coxwold faults, but there are 

no good exposures. The formation is mainly made up of sandy shales and 

flaggy sandstones, with calcareous doggers full of the usual fossils—T. tetrahedra 

> P. cequivalvis, G. cymbium, P. truncata, &c., but apparently no ammonites; 

in places fragments of oolitic ironstone can be detected at the top. 

West of the Hambleton Hills, except for a few exposures at Feliskirk and 

elsewhere, Drift covers the outcrop for several miles to Osmotherley. 

The neighbourhood of Osmotherley, at the south-western corner of the 

Cleveland Hills, is one of great interest stratigraphically. Here an important 

change of facies takes place in the upper part of the Middle Lias, many of 

the bands of flaggy sandstone passing northward into shale, while at the same 

time thin bands of ironstone make their appearance. At Feliskirk there are 

only two thin nodular ironstone bands, 6 and 7 in. thick, but near Osmotherley 

they have multiplied to four, the thickest measuring 2 ft. At first thin beds of 

sandstone and sandy shale alternate, but when the escarpment of the Cleveland 

Hills turns north-eastward the sandstones of the upper part die out, giving 

place entirely to shales with doggery bands and ironstone. The same change 

takes place to the east in the numerous inliers exposed in the sides and 

bottoms of the dales. 

Commensurate with this change of facies in the upper part towards the 

north and east, steady thickening continues. Along the main Cleveland escarpment 

and in the dales the total thickness is first 120 ft. and later 150 ft.; the 

formation thus slightly exceeds its thickness in Leicestershire, but barely 

attains to within 100 ft. of the maximum in the Cotswolds. It is possible, 

moreover, that the thickest measurements include up to 30 ft. of the davoei 

zone of the Lower Lias, which has been proved, at least on the coast, to take 

on a sandy facies in its upper part. 

The lower half remains almost entirely sandstone all over Yorkshire and is 

known as the SANDY SERIES or STAITHES BEDS ; 2 the upper half, which becomes 

chiefly a clay-shale formation with ferruginous bands, is known as the IRON- 

STONE SERIES or KETTLENESS BEDS. 2 

The Ironstone Series of the Middle Lias in the Cleveland Hills is by far 

the richest source of bedded iron ore in England, yielding the greater part of 

the total British output. In the dales and in the more southerly sections on 

the coast, where it crops out round Robin Hood's Bay and Hawsker Bottoms, 

and at Kettleness and Staithes, the Ironstone Series consists of shales with 

numerous thin ironstone bands, not worth mining, though some have in the 

past been worked at their surface outcrop. The most argillaceous development 

of all is found in the most south-easterly exposures, in Robin Hood's 

Bay. The general thickness on the coast is about 100 ft. 

1 First six paragraphs based on C. Fox-Strangways, 1892, J.R.B., Chapter III; for many 

other particulars see J. J. Burton, 1913, 'The Cleveland Ironstone', The Naturalist, pp. 161-8, 

185-94. 

2 Names dating from Young and Bird, 1822.

M I D D L E LIAS: C L E V E L A N D IRONSTONE 

Northward and westward, towards the edge of the Cleveland Hills overlooking 

Middlesbrough, the Ironstone Series as a whole becomes thinner but 

the individual ironstone seams grow thicker and improve in quality. Many of 

the thin bands expand, closing up and pinching out the shales between them, 

while new ones come in, until in the outlying mass of Eston Hill, north of the 

Guisborough Valley, the highest 28 ft. of the series contain 20^ ft. of ironstone. 

The total thickness is here rather less than 80 ft., with perhaps 60-70 ft. of 

Sandy Series beneath. 

These facts explain the location of the principal ironstone workings along 

the northern escarpment of Cleveland and Eston Moor, and they account 

directly for the growth of Middlesbrough, which in 1831, before the coming 

of the iron industry, was a town with a population of only 154 persons. Ninety 

years later the census showed a population of 131,103. The rise of this town 

is a fair measure of the importance of the industry. 

The whole of the six million tons of ore that are raised annually along the 

north slopes of Cleveland are yielded by one seam, known as the Main Seam, 

which varies in thickness from about 6 ft. to 11 ft. In composition it is chiefly 

a carbonate of iron, of a greenish-grey earthy appearance, containing a multitude 

of small ooliths unevenly diffused throughout the mass, and here and 

there small cavities, sometimes filled with carbonate of lime. The iron content 

is as high as 30 per cent., but the advantages of this are to some small extent 

counterbalanced by the lime content being so low (5 per cent.) that large 

quantities of limestone have to be employed as a flux. It is to this circumstance 

that the enormous limestone quarries in the Corallian at Pickering and elsewhere 

are due. 1 

Beneath the Main Seam, which is near the top of the series, there are in the 

iron-producing districts usually three lesser seams, the general section being 

as follows : 2 

Shale (variable) . . . . 

MAIN SEAM IRONSTONE 

Shale . . . . . . 

PECTEN SEAM IRONSTONE AND SHALES . 

Shale . . . . . . 

TWO-FOOT SEAM IRONSTONE 

Shale . . . . . . 

AVICULA SEAM IRONSTONE . 

ft. 

0-6 

6—11 

o-5 

15—21 

20-30 

o-3 

On the north side of Eston Hill the Main Seam and the Pecten Seam are in 

contact, but a shale separates them even before their emergence on the south 

side of the hill. Gradually towards the south-east, down the dip-slope, the 

Main Seam in turn comes to be split up by a shale parting of ever-increasing 

thickness. The NE.-SW. line along which this split in the Main Seam first 

occurs has been determined with great accuracy and is known as the Shale 

Line. 

The ore of the three minor seams is of inferior quality, though all three 

have in certain localities been worked in the past. The Pecten Seam owes its 

1 G. W. Lamplugh, 1920, 'Spec. Repts. Min. Resources', vol. xii, pp. 1-64, Mem. Geol. 

Surv. 

2 C. Fox-Strangways, 1892, loc. cit.

X62 THE LIAS 

name to the abundance of Pseudopecten cequivalvis, the Avicula Seam to 

Oxytoma [.Avicula] incequivalvis. 

Palaeontologically the Yorkshire Middle Lias has received the closest 

investigation outside the ironstone district, at Hawsker Bottoms, south of 

Whitby (Plate VII), at the hands of S. S. Buckman. 1 The Main Seam and the 

shales above and below it are the only part of the series that would appear to 

belong to the spinatum zone. Several species of Paltopleuroceras have been 

recorded under the name spinatum, the commonest form being a thin-whorled 

species, P. hawskerense (Y. and B.). The lower seams of ironstone, therefore, 

occur on horizons below the Marlstone over the rest of England except in the 

Cotswolds, and their inferior quality is thus not to be wondered at. 

Buckman placed the upper limit of the margaritatus zone at the top of the 

Pecten Seam, giving the zone a thickness of 60 ft., to the base of the Ironstone 

Series. The highest 23 ft. of the Sandy Series he called the zone of Seguenziceras 

algovianum, assigning the remainder (about 30 ft.) with ammonites of the 

genus Oistoceras, to the top of the Lower Lias (davoei or capricornum zone). 

The rest of the fauna, however, is typically a Middle Lias one, consisting of 

bands of Gryphcea cymbium, with Protocardia truncata, Oxytoma incequivalvis 

and belemnites, so that Middle Lias conditions may be said to have begun 

here at an earlier date than in the rest of England. In North-West Scotland 

they began even earlier, during jamesoni and even locally in the later part of 

raricostatum times. 

VIII. T H E HEBRIDEAN AREA 

(a) Skye, Raasay, and Scalpa 2 

The surface outcrop of the Middle Lias in the Hebrides is small compared 

with that of the Lower Lias. In South and Central Skye, where the Lower 

Lias is so conspicuous, the Middle is known only from a small patch of unfossiliferous 

sandstone north-west of Broadford, and from some bands of 

sandstone and limestone with Tetrarhynchia tetrahedra, Pseudopecten cequivalvis, 

&c., on the beach and in the base of the cliffs on the west side of Loch 

Slapin. Another small patch occurs on the south-eastern side of the Island 

of Scalpa, faulted down nearly to sea-level against the Torridonian. Here the 

only exposures are reefs between tide-marks on the shore near Scalpa House. 

Both zonal ammonites have been recorded by Judd, as well as the characteristic 

brachiopods. 3 

The best development of the Middle Lias occurs in Raasay, where it makes 

a large part of the high eastern cliffs and strikes SW. across the island. It also 

builds the lower part of the cliffs for 3 miles south of Holm, on the adjoining 

coast of Trotternish, NE. Skye. Lithologically the whole series consists of a 

single mass of sandstone, up to 240 ft. in thickness, which has been called, 

somewhat inappropriately, the SCALPA SANDSTONE. 

Owing to the occurrence of fossils, particularly ammonites, being very 

sporadic, life-zones are difficult to determine. In the course of time, however, 

1 S. S. Buckman, 1915, in 'Geol. Whitby and Scarborough', 2nd ed., pp. 68-74, Mem. 

Geol. Surv. 

2 Based on H. B. Woodward and C. B. Wedd, 1910, 'Geol. Glenelg, Lochalsh and SE. 

Skye', pp. 113-14; and G. W. Lee, 1920, 'Mes. Rocks of Applecross, Raasay and NE. Skye', 

pp. 25-9, Mems. Geol. Surv. 

3 J. W. Judd, 1878, Q.J.G.S.yvol. xxxiv, p. 714.

MIDDLE LIAS: HEBRIDES 163 

sufficient specimens have been obtained, including Paltopleuroceras spinatum, 

P. hawskerense and numerous species of Amaltheus, to warrant the supposition 

that the highest 100 ft. or more of the sandstone belong to the spinatum zone, 

while the rest belongs to the margaritatus zone, with doubtfully a local representative 

of an algovianum horizon at the base (said to be indicated by the 

occurrence of Amaltheus depressus (Simpson) in Mull and a Seguenziceras sp. 

in Raasay). 

The margaritatus sandstones are usually flaggy and micaceous or calcareous, 

and a striking feature of the spinatum portion, especially in Raasay, is a number 

of huge ellipsoidal doggers, up to 6 ft. in diameter. Otherwise there is little 

difference between the two zones. 

(6) Mull and Ardnamurchan 1 

In the southern part of the Hebridean area the Middle Lias occurs in a 

number of places in Mull and on the adjoining mainland of Ardnamurchan. 

The most pronounced feature in this part of the area is a tendency to rapid 

attenuation in short distances in no constant direction. In Carsaig Bay, on the 

south coast of Mull, the maximum thickness exceeds 200 ft. Between Port 

nam Marbh and Port Donain, north of Loch Spelve, the thickness L* reduced 

by a half, while between Loch Spelve and Loch Buie there are only some 40 ft., 

which is the thickness also in Ardnamurchan (see map, p. 114). 

The finest sections are in southern Mull, where the 200 ft. of sandstones 

build the lower part of the cliffs on either side of Carsaig Bay. There is also 

a good section between Port nam Marbh and Port Donain. The main mass 

of the sandstone is presumed to belong to the spinatum zone, though no fossils 

have been found in it. It is white, generally massive, slightly calcareous, and 

capable of being used as a good freestone, except where large doggers are 

developed—a feature especially noticeable in Carsaig Bay. 

Below the unfossiliferous white sandstone are shaly sandstones, which pass 

downward into sandy shales. These last have yielded Amaltheus depressus 

Simpson, indicating the margaritatus zone; and, just as in the more northerly 

islands and in Yorkshire, there is a perfect downward passage into the Lower 

Lias. The physical conditions that gave rise to the type of deposit so characteristic 

of the Middle Lias here began as early as jamesoni times, and with the 

change of conditions came such characteristic members of the Middle Lias 

fauna as Pseudopecten cequivalvis and Gryphcea cymbium. 

In Ardnamurchan no fossils have been found. There is only one complete 

section, on the north coast § mile east of Rudha Groulin, and to this some disconnected 

sections on the south coast add nothing. Fine-grained white sandstone 

makes up the bulk of the formation, and here again it passes downwards 

gradually through shaly sandstone and sandy shale into the Lower Lias. The 

passage upwards into the Upper Lias is equally gradual. 2 

IX. EASTERN SCOTLAND 

No Middle Lias is exposed in Eastern Scotland; with the Upper Lias and the 

Inferior Oolite, it is faulted down out of sight near Dunrobin in East Sutherland. 

1 Based on G. W. Lee, 1925, 'Pre-Tertiary Geol. Mull, Loch Aline and Oban', pp. 92-4, 

Mem. Geol. Surv. 

2 J. E. Richey, 1930, 'Geol. Ardnamurchan', p. 42, Mem. Geol. Surv.

164 THE LIAS 

X. KENT 1 

Like the Lower Lias in Kent, the Middle Lias is restricted to the area south 

and west of the main line of railway from Dover to Canterbury, towards which 

it thins out and with the whole of the Lias is overstepped by the Lower Oolites. 

The greatest thicknesses recorded are in the more south-westerly borings: 

45 ft. at Brabourne, 20-21 ft. at Elham and Dover, 17 ft. at Folkestone, and 

14 ft. at Chilton and Harmansole. 

'Broadly speaking', according to Messrs. Lamplugh, Kitchin and Pringle, 'the 

Middle Lias is developed in a shaly facies in its lower part, with a more pronounced 

limestone-facies above. It has yielded no ammonities, and the evidence is as yet 

insufficient for precise zonal subdivision. But it may be permissible to allocate the 

shales below to the margaritatus zone, the limestone series above to the spinatum 

zone, the boundary between them being as yet uncertain/ 2 

Other palaeontological evidence is fairly abundant, especially in the limestone 

bands, where Tetrarhynchia tetrahedra (Sow.) sometimes occurred in 

large numbers, together with Rhynch. northamptonensis Dav. and Rh. fodinalis 

Tate, Rh. capitulata Tate, and Pseudopecten cequivalvis (Sow.), all fossils highly 

characteristic of the Marlstone at the outcrop in other parts of England. Only 

the absence of Lobothyris is remarkable. 

The shales below are considerably thinner than the limestones and at 

Harmansole they are wanting. At Brabourne they are micaceous and greenishgrey 

in colour, showing close lithic resemblance to the. ubiquitous micaceous 

shales of the margaritatus zone in other parts of the country. They are characterized 

by a lamellibranch assemblage, of which the most important members 

are such species as Modiola scalprum Sow., Protocardia truncata (Sow.), and 

some of the large Pseudopectens which abound in the overlying limestones. 

At Chilton the base of the Middle Lias was marked by a 1 ft. pebble-bed 

described as a 'peculiar pebbly and nodular clayey band with streaks of pebbly 

quartz-grit, mixed with shelly detritus and tubed by boring organisms'. 3 This 

indicates that the rapid change of facies which came in with or slightly before 

margaritatus times was here preceded by earth-movements, probably along 

the margin of the London landmass to the north. 

1 Based on G. W. Lamplugh and F. L. Kitchin, 1911, loc. cit.; and Lamplugh, Kitchin, and 

Pringle, 1923, loc. cit. 

z 1923, loc. cit., p. 197. 

3 1923, loc. cit., p. 75.

YEOV.L SHERBORNE MEND.P5 M.DFORD SODBURY STROUD Co^°SwOLD< ^ L E Y ^ NORTHAMPTON. RE L.NCOLN WEVG^TON ^BASIN* 

FIG, 30. Diagrammatic section of the Upper Lias along the outcrop from Dorset to Yorkshire, showing the changes in thickness and lithology. The boundary between the Whitbian and Yeovilian is reduced to a horizontal plane. 

Horizontal scale: 1 inch = about 20 miles; Vertical scale: 1 inch = about 100 feet.

Substages. 

Faunizones (Zones). 

(Plate XXXII). 

CHAPTER VII 

UPPER LIAS 

LOWER Lioceras CyphoUoceras opaliniforme 

AALENIAN 1 opalinum 1 

YEOVILIAN 2 

YEOVILIAN 2 

WHITBIAN 2 

WHITBIAN 2 

| 

Teilzones or Epiboles 

(Sub zones). Dorset Strata. 

Pleydellia aalensis 

Dumortieria moorei 

Dumortieria spp. 

Lytoceras 

| Phlyseogrammoceras dispansum 

jurensis i Pseudogrammoceras struckmanni 

Grammoceras striatulum 

Haugia variabilis 

Bridport 

Sand 

40 ft. 

| Down Cliff 

; Clay 70 ft. 

(absent) 

Lillia lilli 

Junction 

Hildoceras ; Peronoceras braunianum 

Bed 

bifrons and 

Dactylioceras 

Peronoceras fibulatum ! J 

5 FT. 

commune | Frechiella subcarinata 

Harpoceras Harpoceras falcifer 

falcifer 

Harpoceras exaratum 

Dactylioceras Dactylioceras tenuicostatum 

tenuicostatum 3 

Tiltonoceras acutum 

1 

(absent) 

THE Upper Lias takes on two principal facies: in the lower part, Upper 

Lias Clay; in the upper part, usually yellow sands and sandstones, 

variously known as the Bridport, Yeovil, Midford, Cotswold, and Blea Wyke 

Sands. Locally, at the top and at the bottom, are slowly-accumulated thin beds 

packed with ammonites and called the Cephalopod Beds. 

S. S. Buckman showed by pioneer researches in the South-West of England 

that the sands and clays and Cephalopod Beds of various counties and districts 

were of different dates; that the ammonites crowded into the Cephalopod Bed 

in South Dorset and North Somerset were spread through a great thickness of 

Upper Lias Clay in the Cotswolds, and that the ammonites thinly distributed 

through the Bridport, Yeovil, and Midford Sands of the South-West were to 

be found collected together in the Cephalopod Bed of Gloucestershire. 

1 The opalinum zone (Lower Aalenian) is usually classed with the Inferior Oolite, but, 

purely for convenience in description, it is here grouped with the Upper Lias, of which it is 

the natural upward continuation. 

2 The terms Yeovilian and Whitbian, having been coined especially for the upper and lower 

parts of the English Upper Lias by Buckman, unlike most of the stage-names founded on 

Continental sequences, apply to the English succession exactly. They are very convenient, 

since one cannot speak of Upper Upper Lias and Lower Upper Lias, and they are therefore 

used here. 

3 Ammonites tenuicostatus Young and Bird, erroneously called annulatus by Tate and Blake. 

See S. S. Buckman, 1910, Q.J.G.S., vol. lxvi, p. 87.

120 THE LIAS 

The basis of these conclusions was refinement in the identification of ammonite 

species and horizons. The true sequence was established by careful 

collecting at all available points along the outcrop, and in a series of classic 

papers published between 1875 and 1922 Buckman showed in more and more 

detail how these ammonite horizons transgressed the lithic planes previously 

employed in mapping and stratigraphy. At the same time he led the band of 

palaeontologists who insisted that the faunas must be trusted as chronological 

guides and the lithic planes ignored if chaos was to be avoided—a principle 

which is now hardly questioned. Of all the formations of the Jurassic, the 

Upper Lias is perhaps the best illustration of this principle, for it provides 

a unique combination of multiple and widespread ammonite epiboles and 

differing conditions of sedimentation in different districts (see fig. 30, facing 

p. 165). 

I. THE DORSET-SOMERSET AREA 

(a) The Dorset Coast 1 

The Upper Lias first appears at Seatown, on the downthrown (east) side of 

the fault that lets down the JUNCTION BED between the Middle and Upper 

Lias to the top of Down Cliff. From Seatown it runs eastward almost horizontally, 

but rising slightly, along the face of Thorncombe Beacon to Eypesmouth. 

Beyond this, after appearing for only a short distance at the beginning 

of Watton Cliff, it is cut off by another fault downthrowing to the east 

(fig. 29, p. 154). 

Above the Junction Bed is 70 ft. of the local Upper Lias Clay, better known 

as the DOWN CLIFF CLAY from its forming the top of Down Cliff. Finally, 

capping the clay beneath the Greensand of Thorncombe Beacon, follow the 

bright yellow Bridport Sands (Plates V, VI). These are better seen on either 

side of Bridport Harbour and Burton Bradstock, where they build cliffs of 

curious layered appearance, formed of hard concretionary sandstone bands 

alternating with soft chrome yellow sand. Their total thickness is 140 ft. 

In order to bring out more vividly the changing lithic facies of the various 

zones of the Upper Lias as they are traced across the country and to aid the 

memory, they will be described under their lithological headings, the fauna 

noted, and comparisons drawn with other localities and the standard sequence 

of Dorset—a departure from the usual practice. 

LOWER AALENIAN AND YEOVILIAN, 210 ft. 

BRIDPORT SANDS, 140 ft. The highest bed of the Bridport Sands is the 

Scissum Bed, ft. thick, a hard grey sandstone or sandy limestone here 

regarded as the base of the Inferior Oolite. This bed is exposed in the cliffs 

at Burton Bradstock (but is accessible in only a few places) and also near the 

top of Chideock Quarry Hill farther west. 

For about 25 ft. below the Scissum Bed are brown sands and sand-burrs 

with fragmentary and badly-preserved ammonites of the Pleydellia aalensis 

type, and in the highest 6 ft. the brachiopods Rhynchonellapentaptycta Buck., 

R. stephensi and Zeilleria oppeli. 

1 Based on S. S. Buckman, 1890, Q.J.G.S., vol. xlvi, pp. 518-21; 1910, ibid., vol. lxvi, 

pp. 80-9; 1922, ibid., vol. lxxviii, pp. 378-436; and J. F. Jackson, 1922, ibid., pp. 436-48; 1926, 

ibid., vol. lxxxii, pp. 490-525.

PLATE VIII 

Photo. Purch. 

Cliff of Bridport Sands capped with thin Inferior Oolite, West Bay, 

Bridport Harbour. 

Golden Cap and Thorncombe Beacon (in distance) from Burton Bradstock, 

Cliff of Bridport Sands capped with Inferior Oolite in foreground. 

Purch.

PLATE VIII 

hoio - Godfrey Bingley. 

Cliffs of Whitbian shales overlying Middle Lias, Hawsker Bottom, Whitby. 


Cliffs of Yeovilian Sands (Bridport Sands) near Burton Bradstock. 

The sands and irregular hard bands are bright chrome yellow.

UPPER LIAS: DORSET COAST 167 

The next fossiliferous horizon is about 40 ft. below the Scissum Bed, at 

which level are abundant fine-ribbed Dumortierice indicative of the moorei 

subzone. 

Below come 100 ft. of sands and layers of sand-burrs in which no fossils have 

been found. Buckman assigned them tentatively to the moorei subzone. 1 The 

transition to the clay below is abrupt. 

UPPER LIAS CLAY (DOWN CLIFF CLAY), 70 ft. This is a uniform blue-grey 

clay, becoming sandy towards the base. Buckman records the following 

ammonites: 

At 12 ft. down: Dumortieria cf. striatulocostata, D. cf. radians, D. cf. 

pseudoradiosa. 

At 40 ft. down: Dumortierice fragments. 

At 50 ft. down: D. cf. costula. 

At the base: D. cf. striatulocostata. 

The clay everywhere rests abruptly and non-sequentially, with the absence 

of the struckmanni and dispansum subzones found in other parts of England, 

upon the surface of the Junction Bed, the greater part of which belongs to the 

Whitbian. 

WHITBIAN 

JUNCTION BED, 2J-4J ft. In the Junction Bed four separate ammonite subzones 

can be recognized, embracing three of the five zones of the Upper Lias 

and part of the topmost zone of the Middle Lias: namely the subzones of 

striatulum, bifrons, falcifer and spinatum. 

The Upper Lias part contains three layers. Wherever the upper surface of 

the topmost or striatulum layer can be examined it shows evidence of protracted 

but quiet erosion before the deposition of the Down Cliff Clay. It is planed 

off perfectly level, so that the ammonites are displayed in section, sometimes 

'almost as accurately cut through as if sliced on a lapidary's wheel'. 2 The 

matrix varies from a hard rubbly buff limestone to a soft earthy marl, with 

harder lumps and limonitic nodules. The fossils are sometimes rolled and 

perished. 

The bifrons layer is a tough limestone with a smoothed top, on which the 

striatulum layer reposes with perfect conformity. It is sometimes wholly 

fine-grained, but generally contains pebbles of a similar rock, together with 

a mixture of fresh and derived specimens of Hildoceras bifrons and Dactylioceras 

commune. The bifrons layer is subdivided by two or three minor planes 

of erosion, and occasionally the ammonites on these planed surfaces are in the 

same condition as those at the top of the striatulum layer. The removal of 

the upper parts of ammonites, often standing highly inclined or even vertically, 

while the lower parts remained held in the matrix, is proof that the rock 

must have become completely consolidated before the erosion took place. 

The division between the bifrons and falcifer layers is usually rather obscure. 

The falcifer layer is a tough yellowish-pink limestone, often mottled with 

red, occasionally greenish. It varies from a fine-grained compact rock to a 

1 For the sake of simplicity the word 'subzone' is used throughout this chapter, where it 

occurs with especial frequency. For a discussion of its true meaning (epibole or teilzone) see 

pp. 17-35. As i n the Lower Lias chapter, 4 zone* implies faunizone. 

2 J. F. Jackson, 1922, Q.J.G.Svol. lxxviii, p. 437.

168 THE LIAS 

conglomerate of pebbles of similar limestone with broken and rolled Harpocerates. 

As in the bifrons layer, there are several minor planes of erosion 

within the layer. The falcifer layer rests upon a planed-ofF surface of the 

Middle Lias Marlstone, either welded to it, or separated by a thin ferruginous 

seam with Pleurotomaria mirabilis Desl. and P. subnodosa Goldf. (? = P. 

precatoria Day). 

Three-quarters of a mile to the east of the point where the Junction Bed 

runs out on the side of Thorncombe Beacon, it reappears for a short distance 

on the other side of Eypesmouth, where it abuts against the great fault of 

Watton Cliff. In this exposure it is thicker (4 ft. 7 in.) and all the various layers 

have changed their lithic characters to such an extent that they are unrecognizable. 

Buckman attributed the changes in so short a distance to proximity 

to the Weymouth anticline. 1 

(b) Somerset 

Between Bridport on the coast and Ilminster in Somerset, where the outcrop 

turns eastwards, little is known of the lower part of the Upper Lias owing to 

the poverty of outcrop and lack of exposures. But from Ilminster it is persistent 

through the rest of Somersetshire to the Mendips. 

In general the main divisions of the formation in Somerset resemble those 

seen on the coast, but there are certain interesting differences. 

LOWER AALENIAN AND YEOVILIAN, 185 ft. 

YEOVIL (and BRIDPORT) SANDS, 185 ft. 2 The Bridport Sands of the coast can 

be followed inland past Stoke Knap and Broad Windsor into Somerset, where 

in the Crewkerne and Ilminster district they thicken to rather over 180 ft. 

The thickening is due to the extension of the sands downwards into the 

Dumortierice subzone, and the replacement of the whole of the Down Cliff 

Clay by an arenaceous facies continuous with the Bridport Sands above. The 

Yeovil Sands, therefore, are equivalent to the Bridport Sands plus the 'Upper 

Lias Clay' of the coast. 

In the Ilminster and Crewkerne district 3 the top beds of the sands are usually 

indurated. At the top is a Scissum Bed of hard sandy limestone or calcareous 

sandstone. Beneath this the next few feet of the sands are also sometimes 

indurated, or at least form a coherent sandstone, and yield CyphoUoceras 

opaliniforme. At Whaddon Hill, near Beaminster, the opaliniforme subzone 

is represented by beds full of brachiopods. The subzone of Pleydellia aalensis 

has been detected at Furzy Knaps, near Seavington, where it yields P. leura 

Buck., Canavarina venustida Buck., and Cotteswoldia subcandida Buck. At 

North Perrott Pleydellia aalensis occurs in a remanie bed, and somewhere 

between North Perrott and Yeovil Junction the aalensis, opaliniforme and 

scissum zones die out, for in the Sherborne district (except for a trace at 

Marston Road Quarry 4 ) they have disappeared, leaving Inferior Oolite limestones 

of the murchisonce zone resting directly on sands of moorei date. 

1 It should be noted that the section of the Junction Bed at Watton Cliff was first described 

from a slipped block upside-down, an error which caused embarrassing difficulties and 

much theoretical discussion. The mistake was discovered and corrected by Mr. Jackson in 

a later paper (1926, Q.J.G.S., vol. lxxxii, p. 511). 

2 S. S. Buckman, 1889, Q.J.G.S., vol. xlv, pp. 440-73. 

3 L. Richardson, 1918, Q.J.G.S., vol. lxxiv, pp. 148-63. 

4 L. Richardson, 1930, Proc. Cots. N.F.C., vol. xxiv, p. 70.

UPPER LIAS: SOMERSET 169 

The main bulk of the Yeovil Sands in Somerset consists of chrome yellow 

sand with lines of sand-burrs, and belongs to the moorei and Dumortierice 

subzones. In the Crewkerne and Ilminster district there is an interesting local 

development of a thick limestone in the moorei subzone. It first appears at 

North Perrott in the form of a hard brown limestone, 18 ft. thick, largely made 

up of shell-fragments, and called the PERROTT STONE. 1 It thickens rapidly 

towards the great earthwork-encircled bluff of Hamdon Hill, 5 miles west of 

Yeovil, where it has been quarried since mediaeval days as a renowned building 

stone under the name of HAM HILL STONE. The best freestone at Ham Hill 

occurs in immense blocks consisting of a mass of comminuted shells, and 

lends itself to sawing and working into elaborate designs. It is 50 ft. thick and 

the sand for 30 ft. above it contains occasional layers of similar but rougher 

stone. Homceorhynchia cynocephala and very rarely an ammonite of the genus 

Dumortieria occur in the freestone, and in the sands, 55 ft. below, Buckman 

found a fragment of Dumortieria rhodanica in a hard band. 2 

The Ham Hill Stone is purely a local development or facies of the Yeovil 

Sands, and in a distance of 6 miles towards the east it thins down to 2 ft. at 

Stoford. Here it is similar in appearance, and is still used for building, but 

the shells are less comminuted and are identifiable. They include Dumortieria 

moorei (Lyc.), Z). subundulata (Branco), Grammoceras mactra Dum., 

Trigonia literata, Astarte elegans and Ceratomya bajociana. Still farther east, 

at Bradford Abbas near Sherborne, the same subzone and probably even the 

same horizon is identifiable in a foot or two of hard, shelly, sandy limestone 

called the Dew Bed or Dhu Bed, which yields the same fauna. 3 

Near Yeovil a large proportion of the lower part of the Yeovil Sands passes 

into hard micaceous sandy shale. The base of the sands is rarely visible, but 

it was exposed in a recent excavation at Barrington, near Ilminster, where it 

yielded Phlyseogrammoceras dispansum and Dumortieria? sp., an indication 

of the presence of a subzone undetected in Dorset. Below this, resting on a 

rock-band equivalent to the Junction Bed, were 6 in. of black clay with 

Hammatoceras cf. insigne, Grammoceras spp., Pseudogrammoceras cf. grunowi 

(Dum. non Hauer), Haugia sp., and Hildoceras sp. 4 

WHITBIAN 

UPPER LIAS CLAY, 5-10 ft. As on the coast, the zones of the Whitbian are 

very much attenuated. They consist of from 5 to 10 ft. of blue, grey and brown 

marly clay with thin, irregular, nodular and impersistent bands of pale, earthy 

limestone, rich in ammonites indicative of the bifrons and falcifer zones. 

Occasionally the calcareous bands coalesce to form a white limestone. In the 

recent exposures at Barrington, referred to above, Dactyliocerate ammonites 

were more abundant and better preserved than at any other locality in England. 

So great was the wealth of forms collected in situ, inch by inch, that one of 

Buckman's last actions, in the last part of Type Ammonites published in his 

lifetime, was to found upon them twenty new 'genera' of Dactylioceras. 5 


2 S. S. Buckman, 1889, Q.J.G.S., vol. xlv, p. 449; and L. Richardson, 1911, P.G.A., 

vol. xxii, pp. 258-60. 

3 S. S. Buckman, 1893, Q.J.G.S., vol. xlix, p. 485. 

4 J. Pringle and A. Templeman, 1922, Q.J.G.Svol. lxxviii, p. 450. 

5 T.A., vol. vi, 1926, pp. 41-6.

i7o THE LIAS 

A note of warning (and of comfort) about these is sounded by Dr. Spath. 1 

'Such Upper Liassic successions as that of Barrington', he writes, 'are now recognized 

to be of only very limited value for wider correlations on account of local accidents 

of collecting, horizontal distribution of species, See.' 'The Dactyliocerates, with their 

apparently infinite diversity, are a group to mislead those who are insufficiently 

acquainted with ammonite development as a whole. There are already too many of 

these ammonite "species". The collection of the late Mr. James Francis, recently 

presented to the British Museum, contains a large number of similar Whitby forms 

of doubtful horizons in the Upper Lias that are probably all referable to known 

species and their varieties. Now the whole outlook on ammonites has changed, it is 

not considered advisable to name more of these' 'types". Some authors may disagree, 

and I am prepared for the usual threadbare arguments to justify the naming of each 

ammonite individual with a (supposititious) hemera of its own. When the necessary 

zonal collecting in the Upper Lias has been done it will be found that these numerous 

names are a hindrance rather than a help ... in other words, this "modern'' method 

urgently requires bringing up to date'. 

The lowest of the nodular limestone bands is of the greatest interest and is 

know r n as the SAURIAN AND FISH BED. The nodules, which are up to 6 in. 

thick and sometimes septarian, often enclose bones and other fossils, of which 

a magnificent collection was made by Charles Moore and may now be seen in 

the museum at Bath. The ammonites were considered by Buckman to indicate 

the exaratum subzone, a horizon lower than any detected on the Dorset 

coast. Among the products of this bed are Ichthyosaurus acutirostris, Pelagosaurus 

typus, P. moorei, Lepidotus, Leptolepis, Hybodus, Pachycormus, Coleia 

moorei, Penceus sp., and Palinurina sp.; also the belemnite Acrocoelites ilminsterensis 

(Phil.) with ink-sacs preserved, insects and plant remains. 2 

Below this bed in the Ilminster district is i ft. i in. of green, yellow, and 

brown clay called the LEPTTENA BED, with a remarkable fauna of brachiopods: 

Leptcena (Koninckella) bouchardi, L. moorei, Thecidium rusticum, Spiriferina 

ilminster ensis, Zellania liassica, Terebr atula globidina, Rhynchonella pygmcea; 

also ostracods and foraminifera. 

Finally, the topmost 10 in. of the Marlstone yield species of Dactylioceras, 

which are sufficient to indicate the basal zone of the Whitbian (zone of Dactylioceras 

tenuicostatum) and with this zone, on the strength of evidence obtained 

farther north, the Leptcena Beds should probably be classed. Harpoceras 

falcifer and H. exaratum occur together in a clay band between limestones 

within a foot of the top of the Marlstone at Batcombe, near the Mendip 

Axis. 3 

II. THE MENDIP AXIS: FROME AND BATH DISTRICT 

To within a short distance of the south side of the Mendip Hills the Upper 

Lias, like the Middle and Lower, is essentially normal and well-developed. 

On the outliers of Glastonbury Tor and Brent Knoll the Whitbian consists 

of from 10-15 ft- °f compact, earthy limestone bands and clay, full of ammonites 

of the bifrons and falcifer zones, overlain by about 30-35 ft. of 'Upper 

1 Naturalist, 1926, p. 321. 

2 Charles Moore, 1867, Proc. Somerset Arch. N. H. Soc., vol. xiii, pp. 130-3, gives a figure 

of the old section at Strawberry Bank, Ilminster, from which the collections were obtained. 

The macruous crustacea have been revised by H. Woods, 1925, 'Mon. Foss. Mac. Crustacea', 

Pal. Soc., pp. 3, 26, See. 

3 L. Richardson, 1909, Geol. Mag. [5], vol. vi, pp. 540-2.

UPPER LIAS: MENDIPS 171 

Lias Clay', the zonal position of which is not known with certainty. 1 From 

ammonites found in an analogous clay on the Dundry outlier on the North 

side of the Mendips, it may be presumed to be a return of the Down Cliff 

Clay belonging to the Dumortierice subzone. The sandy Yeovilian caps the 

outliers with thick sands and sandstone bands, 175 ft. thick on Glastonbury 

Tor and about 200 ft. thick on Brent Knoll. 

Northward along the main outcrop, however, clays and sands and all traces 

of the Upper and Middle Lias die out completely. As previously mentioned, 

all the exposures south of the Wellow Valley show Upper Inferior Oolite 

resting directly on the davcei zone at the top of the Lower Lias, which is itself 

in some places eroded down until only 8 ft. is left. 

At Wellow, 4 miles north-east of Radstock, pockets of earthy ironshot limestone 

up to 1 \ ft. thick are left between the Lower Lias and the Inferior Oolite 

as the sole relics of the Upper Lias. Four layers can be recognized in these 

pockets: the topmost is much bored by Lithophaga; the next contains Pseudogrammoceras 

doerntense Denckmann, mixed with Hildoceras bifrons; the next 

contains Hildoceras and Dactylioceras; the lowest Harpoceras falcifer and 

ammonites perhaps of the bifrons zone. 

Barely a mile farther north, at Timsbury Sleight (map, fig. 13, p. 70), the 

mere pockets of Upper Lias have thickened to a continuous stratum containing 

miniature representatives of most of the zones of the formation. Once 

again the normal division into sands above and cephalopod limestones below 

can be applied—5 ft. of yellow sands and 4 ft. of ironshot brown limestones. 

The topmost bed of the sands (3 in.) is hardened and in places conglomeratic, 

and yields Dumortieria subsolaris Buck. The rest of the sand is unfossiliferous, 

but from neighbouring exposures it is known to belong to the dispansum 

subzone, and to be the first appearance of the MIDFORD SANDS. The 4 ft. of 

ironshot oolitic limestone is almost exactly equivalent to the Junction Bed of 

the Dorset coast, except that its topmost layer contains Pseudogrammoceras 

doerntense Denckmann, and Ps. quadratum (Haug), indicating the struckmanni 

subzone, which is unrepresented in Dorset. The central layers contain 

Ps. pedicum Buck, and other species, and Esericeras incequum Buck, which are 

sometimes considered to denote separate subzones under the names pedicum 

and eseri; the basal layers contain Grammoceras penestriatulum Buck, and 

Gr. toarcense (d'Orb.) (striatulum subzone), Hildoceras hildense (Y. and B.), 

and allied species, Dactylioceras commune (Sow.) and D. annuliferum (Simpson) 

(bifrons zone). 2 

At the well-known locality of Midford, north-east of Wellow Railway Station, 

the Midford Sands have expanded in 2 miles from nothing to 100 ft. They are 

best seen in a road-cutting south of the viaduct, and at Greenway Lane and 

Lyncombe railway-cutting to the north, i\ miles away, at both of which 

places they are overlain by the Upper Inferior Oolite. The upper 65 ft. are 

unknown palaeontologically, but lines of sand-burrs in the lower 35 ft. have 

yielded Grammoceras fallaciosum and Ps. struckmanni (dispansum and struckmanni 

subzones). They rest on a Junction Bed or Cephalopod Bed from 1 \ to 

ft. thick, consisting of sandy limestone shot with oolite grains. As usual it 

1 H. B. Woodward, 1893, J.R.B., p. 262. 

2 J. W. Tutcher, 1925, Q.J.G.Svol. lxxxi, p. 621; and L. Richardson, 1907, ibid., vol. lxiii, 

pp. 413-16. 

854371 

N

168 THE LIAS 

is divisible into layers, firmly cemented together: the upper layer contains 

G. striatulum; the middle layer H. bifrons, D. holandrei, and D. crassum; and 

the lowest layer Harpoceras falcifer. 1 

A change, then, is found on crossing to the north side of the Mendip Axis, 

namely the migration of the lower boundary of the Yeovil Sands downward 

into the dispansum and struckmanni subzones, which are unrepresented in 

Dorset but would be expected below the base of the Down Cliff Clay. Nevertheless 

Prof. Boswell has shown that the sands of different ages on the two 

sides of the axis cannot be distinguished petrologically; the source of their 

materials was apparently the same. 

III. THE COTSWOLD AREA 

(a) Dundry Hill 2 and the South and West Cotswolds 3 

On passing northward into the Cotswolds the downward migration of the 

sand is found to continue into progressively lower subzones, while the 

opalinum zone and the upper subzones of the jurensis zone, the equivalents of 

the sands in Dorset, thin down to a few feet of limestone, the COTSWOLD 

CEPHALOPOD BED. This resembles the Junction Bed of the coast, but it contains 

a completely different suite of ammonites and its position is above 

instead of below the sands and clay. 

The first signs of the Cotswold Cephalopod Bed are met with on Dundry 

Hill outlier, about io miles to the west of the main outcrop near Timsbury 

Sleight. Here the opaliniforme and aalensis subzones are compressed into 

i ft. 9 in. of ironshot limestone, continuous with the murchisonce limestones of 

the Inferior Oolite above. But there is also a remarkable feature, already 

foreshadowed in the Glastonbury and Brent Knoll outliers south of the 

Mendips, in the form of a return of the Down Cliff Clay, 6o ft. thick, in its 

original position in the Dumortierice subzone. Beneath the clay a second band 

of ironshot limestone (the Blue Ironshot Bed, i ft.—i ft. 6 in.), as in the Midford 

district, contains layers representing the dispansum, striatulum, bifrons, and 

falcifer subzones, the last in a pinkish seam at the base (the Pink Bed, 2-3 ft.). 

The Upper Lias of Dundry, therefore, consists of 60 ft. of Dumortieria clay 

with a thin band of ironshot limestone at top and bottom, the upper representing 

part of the Cotswold Cephalopod Bed, the lower the Dorset Junction Bed. 

Along the main outcrop of the South Cotswolds, the whole of the clay and 

the upper limestone bed of Dundry become absorbed into the Cephalopod 

Bed, while the zones below expand to form first the Midford Sands, and later 

the Cotswolds Sands. 

THE CEPHALOPOD BED maintains a partly ironshot character along most of 

the outcrop, consisting typically of layers of fossiliferous ironshot marl and 

limestone, often crowded with ammonites. 

In the southern part of the escarpment, about Bath and as far north as 

Dodington, the unconformable overstep of the Upper Inferior Oolite cuts 

out all the highest subzones of the Upper Lias. The top of the sands is of 

1 L. Richardson, 1907, Q.J.G.S., vol. lxiii, pp. 406-8, and Table 2. 

2 S. S. Buckman and E. Wilson, 1896, Q.J.G.S., vol. Iii, pp. 669-720. 

3 Based on S. S. Buckman, 1889, Q.J.G.Svol. lxv, pp. 440-6, and 'Mon. Ammonites Inf. 

Oolite', Pal. Soc.; and L. Richardson, 1910, Proc. Cots. N.F.C., vol. xvii, pp. 63-136.

UPPER LIAS: SOUTH COTSWOLDS 173 

dispansum date, and there is thus a non-sequence corresponding with the whole 

of the Aalenian and Bajocian Stages. 

In a short distance towards the north the gap is rapidly filled, for at Little 

Sodbury there are 14 ft. of Lower Inferior Oolite and beneath it 11 ft. of 

Cephalopod Bed—ironshot marls and limestones, yielding ammonites of 

opaliniforme, aalensis, moorei, Dumortierice and even dispansum dates. 1 Here, 

therefore, the upper part of the Midford Sands is beginning to turn into 

Cephalopod Bed. 

Six to ten miles farther north, at Wotton under Edge and Nibley Knoll, 

the dispansum, struckmanni and striatulum subzones have lost their sandy facies 

entirely and have all become a part of the Cephalopod Bed, which measures 

some 14 ft. in thickness. Here the layers include ammonites of striatulum to 

opaliniforme dates. The deposits of dispansum, struckmanni and striatulum 

dates, which form the thick Midford Sands farther south, are already verythin, 

and before reaching Haresfield Beacon they disappear altogether. 2 

The Cephalopod Bed attains its greatest thickness in the neighbourhood 

of Dursley and Stroud, the measurement at Stinchcombe, near Dursley, 

being 20 ft. Beyond this it diminishes again, and near Painswick, seven miles 

to the north-east, only 1 ft. 10 in. is left. 

MIDFORD AND COTSWOLD SANDS. At the extreme south of the South Cotswolds 

the Midford Sands continue, lying within the dispansum, struckmanni 

and possibly in part within the striatulum subzones, and directly overlain by 

the Upper Inferior Oolite. Gradually towards the north the sands migrate 

downward into successively lower subzones while the upper parts pass into 

new accretions to the Cephalopod Bed. By Little Sodbury the Sands are 

already COTSWOLDS SANDS and 185 ft. thick, occupying the striatulum—lilli 

subzones. Here the greater part is of striatulum date, but 6 miles farther along 

the escarpment, at Wotton Hill Quarry, above Wotton under Edge, the 

striatulum subzone has joined the Cephalopod Bed, and consists of only 

1 ft. 2 in. of ironshot limestone containing Grammoceras striatulum and G. 

toarciense, welded to the base of the other layers of the Cephalopod Bed. 

Here the Cotswold Sands are 123 ft. thick and seem to fall mainly in the 

variabilis and lilli subzones, but partly also in the bifrons zone, for clay with 

Harpoceras falcifer lies immediately below. 

The Cotswold Sands reach thicknesses of 230 ft. at Stinchcombe, 130-40 ft. 

in Coaley Wood near Nympsfield, 3 and 190 ft. at Haresfield Beacon, west 

of Painswick. The lowest extension proved is about Frocester Hill, near 

Nympsfield, south-west of Stroud, where there is a band full of Hildoceras 

bifrons and still 40 ft. of sands below. 4 

As a result of penological examination of the sands of various ages in the 

Cotswolds and the West of England, Prof. Boswell has been able to show that 

the source of the sands, which began to be deposited first about Frocester 

Hill and spread south over Somerset and Dorset through succeeding hemerae, 

was always the same, the composition and grade remaining constant throughout. 

He found that 'the sands differ markedly in petrology from the various 

1 L. Richardson, 1910, loc. cit., pp. 93-4. 

2 Ibid., pp. 105-7. 

3 Ibid., 113, 116. 


168 

THE LIAS 

Palaeozoic rocks of Wales and the West Country, from the Trias, and from the 

Cretaceous and Eocene of Devon and Dorset', 1 and he concluded that they 

re probably derived from the south-west, in the direction of Brittany. This 

W suit is rather difficult to reconcile with their first appearance in the Cots- 

T %\ds, while clay was still being deposited along the rest of the outcrop 

farther south. We may, perhaps, suppose them to have been brought by a 

rjver flowing round the Bristol Channel and debouching north of the Mendip 

Axis into the south of the Cotswold Basin. 

UPPER LIAS CLAY AND JUNCTION BED. Beneath the sands in the South 

Cotswolds are thin argillaceous representatives of the lowest zones of the 

Whitbian, but owing to lack of sections they are little known palaeontologically. 

In the outskirts of Bath, at Primrose Hill, east of Weston, the Midford 

Sands rest upon a basal Junction Bed of bifrons date, as at Timsbury Sleight. 2 

At Little Sodbury the base of the sands is marked by a pyritous layer full of 

Hildoceras bifrons, beneath which is a compact marly limestone with Dactylioceras 

commune, overlying cream-coloured compact marl with Harpoceras 

falcifer. These basal beds, w T hich rest upon the Marlstone, together measure 

10 ft. in thickness. They were penetrated by the Sodbury Tunnel. 

At Wotton Hill Quarry, Wotton under Edge, the Cotswold Sands are 

separated from the Marlstone by 10 ft. of grey, sandy clay with nodules, 

apparently of falcifer date. A few miles farther north these basal beds become 

more predominantly argillaceous and much thicker, forming the 'Upper Lias 

Clay'. At Cam Long Down, north of Dursley and Uley, the clay is estimated 

to have a thickness of 70 ft. 3 

(b) The Central and North Cotswolds 

North of Frocester the Upper Lias Clay thickens greatly at the expense of 

the sands, which dwindle from 230 ft. to almost nothing between Stinchcombe 

and Leckhampton Hill, Cheltenham. The clay is 130 ft. thick at 

Haresfield Beacon and attains a maximum of about 270 ft. in the Mid-Cotswolds 

(at Cleeve Hill and on the outlier of Bredon Hill). At first it continues 

to be capped here and there by traces of sand, probably always of variabilis 

date, directly overlain by the Scissum Beds (for instance at Leckhampton Hill). 4 

At Bredon Hill, however, where the whole 270 ft. consists of clay with 

occasional bands of limestone-nodules, the missing zones return and nearly 

the complete sequence of the Upper Lias is represented in clay facies up to 

the moorei subzone. There are no exposures, but Buckman obtained evidence 

for the existence of the moorei, Dumortierice, struckmanni and variabilis 

subzones in the ammonites obtained from claystone nodules in a gravel pit 

and a gateway on the hill. 5 

From these facts it may be inferred that a minor anticlinal uplift is crossed 

in passing from the Stroud district into the Mid-Cotswolds east of Cheltenham, 

and that its axis corresponds with the Birdlip Anticline, so conspicuous 

1 P. G. H. Boswell, 1924, Geol. Mag., vol. lxi, p. 262. 


3 L. Richardson, 1910, loc. cit., pp. 106, 114. 

4 The Geological Survey maps depict a continuous layer of Cotswold Sand as far east as 

Stow on the Wold, but this is in most places sandy Scissum Beds. See L. Richardson, 1929, 

'Geol. Moreton in Marsh', Mem. Geol. Surv., p. 28. 

s S. S. Buckman, 1903, Q.J.G.S., vol. lix, pp. 445-64.


in the Inferior Oolite (see p. 75). Bredon Hill and the Mid-Cotswolds lie 

in a synclinal trough between the anticlines of Birdlip and the Vale of Moreton. 

In this synclinal area, where the Upper Lias and Inferior Oolite attain their 

fullest development, the falcifer and tenuicostatum zones are represented by an 

interesting SAURIAN AND FISH BED and paper-shales with a micromorphic 

brachiopod fauna—the LEPTTENA BED—as in the Ilminster district of Somerset. 

The presence of the same beds was recognized by Charles Upton also in the 

Stroud district, in the corresponding synclinal area on the south side of the 

Birdlip Anticline. 1 

These fossiliferous beds were exposed many years ago at Gretton, near 

Winchcombe, and on the adjoining Dumbleton outlier, whence they were 

known as Dumbleton Beds. The Saurian and Fish Bed consisted of 6 to 12 in. 

of laminated nodules of limestone with Dapedius, Euthynotus, Leptolepisf 

Pachycormus, Pholidophorus and Tetragonolepis among the fish, and numerous 

insect remains which are still under investigation. 2 Beneath were 20 ft. of 

paper-shales w T ith some lines of nodules and the small Terebratula globulina 

and Rhynchonella pygmcea; and at the base was a layer with ammonites of the 

tenuicostatum zone, forming the top of the Marlstone. Discoveries by Prof. 

Trueman of D. tenuicostatum in similar paper-shales over the Marlstone in 

Lincolnshire provide a comparison for the dating of this lower part of the 

Dumbleton Beds. 3 

IV. THE VALE OF MORETON AXIS AND OXFORDSHIRE 

Eastward, towards the Vale of Moreton Axis, the Upper Lias (and the 

Inferior Oolite) thin out rapidly, and the sandy facies does not return. The 

Upper Lias Clay is only about 80 ft. thick along the western side of the Vale 

of Moreton, at the Bourtons, Stow on the Wold and Burford, and the upper 

zones are shown to be probably missing again, as around Birdlip, by the discovery 

of ammonites of the bifrons zone a few feet below the Scissum Beds near 

Stow on the Wold. 4 

Towards the Evenlode Valley further diminution in thickness reduces the 

Upper Lias to about 30-40 ft. at Chipping Norton, 20 ft. at Milton under 

Wychwood, 5-12 ft. at Fawler, near Charlbury, and 14 ft. under Oxford 

(proved in a boring at Wytham). The most reduced representation of the 

Upper Lias is to be seen in the old Marlstone workings at Fawler, where little 

but an unfossiliferous clay-band, 5-12 ft. thick, separates the ironstone from 

an attenuated representative of the Inferior Oolite. Nearly all the Whitbian 

zone-fossils are present at the base of the clay, in a thin layer of earthy limestone 

crowded w T ith ammonites. 5 In a railway-cutting near Bloxham Railway 

Station, on the west side of the Cherwell Valley, the acutum, tenuicostatum and 

exaratum subzones appear to be absent. A thin bed of limestone of falcifer 

date was found welded to the top of the Marlstone, above which followed 

clays of the bifrons zone, yielding Frechiella subcarinata. This locality lies 

some distance to the north of Fawler, and the total thickness of Upper Lias 

clay is 70 ft. 6 (see discussion on pp. 66-7 above). 

1 C. Upton, 1906, Proc. Cots. N.F.C., vol. xv, pp. 201-7. 

2 For revised list of fossils see Richardson, 1929, loc. cit., pp. 32-3. 

3 See below, p. 179. 


5 W. J. Sollas, 1926, in Nat. Hist. Oxford District, p. 35; and J.R.B., 1893, p. 268. 

6 L. Richardson, 1921, Geol. Mag., vol. Iviii, pp. 426-7.

168 THE LIAS 

Palaeozoic rocks of Wales and the West Country, from the Trias, and from the 

Cretaceous and Eocene of Devon and Dorset*, 1 and he concluded that they 

were probably derived from the south-west, in the direction of Brittany. This 

result is rather difficult to reconcile with their first appearance in the Cotswolds, 

while clay was still being deposited along the rest of the outcrop 

farther south. We may, perhaps, suppose them to have been brought by a 

river flowing round the Bristol Channel and debouching north of the Mendip 

Axis into the south of the Cotswold Basin. 

UPPER LIAS CLAY AND JUNCTION BED. Beneath the sands in the South 

Cotswolds are thin argillaceous representatives of the lowest zones of the 

Whitbian, but owing to lack of sections they are little known palaeontologically. 

In the outskirts of Bath, at Primrose Hill, east of Weston, the Midford 

Sands rest upon a basal Junction Bed of bifrons date, as at Timsbury Sleight. 2 

At Little Sodbury the base of the sands is marked by a pyritous layer full of 

Hildoceras bifrons, beneath which is a compact marly limestone with Dactylioceras 

commune, overlying cream-coloured compact marl with Harpoceras 

falcifer. These basal beds, which rest upon the Marlstone, together measure 

10 ft. in thickness. They were penetrated by the Sodbury Tunnel. 

At Wotton Hill Quarry, Wotton under Edge, the Cotswold Sands are 

separated from the Marlstone by 10 ft. of grey, sandy clay with nodules, 

apparently of falcifer date. A few miles farther north these basal beds become 

more predominantly argillaceous and much thicker, forming the 4 Upper Lias 

Clay\ At Cam Long Down, north of Dursley and Uley, the clay is estimated 

to have a thickness of 70 ft. 3 

(b) The Central and North Cotswolds 

North of Frocester the Upper Lias Clay thickens greatly at the expense of 

the sands, w^hich dwindle from 230 ft. to almost nothing between Stinchcombe 

and Leckhampton Hill, Cheltenham. The clay is 130 ft. thick at 

Haresfield Beacon and attains a maximum of about 270 ft. in the Mid-Cotswolds 

(at Cleeve Hill and on the outlier of Bredon Hill). At first it continues 

to be capped here and there by traces of sand, probably always of variabilis 

date, directly overlain by the Scissum Beds (for instance at Leckhampton Hill). 4 

At Bredon Hill, however, where the whole 270 ft. consists of clay with 

occasional bands of limestone-nodules, the missing zones return and nearly 

the complete sequence of the Upper Lias is represented in clay facies up to 

the moorei subzone. There are no exposures, but Buckman obtained evidence 

for the existence of the moorei, Dumortierice, struckmanni and variabilis 

subzones in the ammonites obtained from claystone nodules in a gravel pit 

and a gateway on the hill. 5 

From these facts it may be inferred that a minor anticlinal uplift is crossed 

in passing from the Stroud district into the Mid-Cotswolds east of Cheltenham, 

and that its axis corresponds with the Birdlip Anticline, so conspicuous 

1 P. G. H. Boswell, 1924, Geol. Mag., vol. lxi, p. 262. 



4 The Geological Survey maps depict a continuous layer of Cotswold Sand as far east as 

Stow on the Wold, but this is in most places sandy Scissum Beds. See L. Richardson, 1929, 

'Geol. Moreton in Marsh', Mem. Geol. Surv., p. 28. 

5 S. S. Buckman, 1903, Q.J.G.S., vol. lix, pp. 445-64.


in the Inferior Oolite (see p. 75). Bredon Hill and the Mid-Cotswolds lie 

in a synclinal trough between the anticlines of Birdlip and the Vale of Moreton. 

In this synclinal area, where the Upper Lias and Inferior Oolite attain their 

fullest development, the falcifer and tenuicostatum zones are represented by an 

interesting SAURIAN AND FISH BED and paper-shales with a micromorphic 

brachiopod fauna—the LEPTTENA BED—as in the Ilminster district of Somerset. 

The presence of the same beds was recognized by Charles Upton also in the 

Stroud district, in the corresponding synclinal area on the south side of the 

Birdlip Anticline. 1 

These fossiliferous beds were exposed many years ago at Gretton, near 

Winchcombe, and on the adjoining Dumbleton outlier, whence they were 

known as Dumbleton Beds. The Saurian and Fish Bed consisted of 6 to 12 in. 

of laminated nodules of limestone w r ith Dapedius, Euthynotus, Leptolepis, 

Pachycormus, Pholidophorus and Tetragonolepis among the fish, and numerous 

insect remains which are still under investigation. 2 Beneath were 20 ft. of 

paper-shales with some lines of nodules and the small Terebratula globulina 

and Rhynchonella pygmcea; and at the base was a layer with ammonites of the 

tenuicostatum zone, forming the top of the Marlstone. Discoveries by Prof. 

Trueman of D. tenuicostatum in similar paper-shales over the Marlstone in 

Lincolnshire provide a comparison for the dating of this lower part of the 

Dumbleton Beds. 3 


Eastward, towards the Vale of Moreton Axis, the Upper Lias (and the 

Inferior Oolite) thin out rapidly, and the sandy facies does not return. The 

Upper Lias Clay is only about 80 ft. thick along the western side of the Vale 

of Moreton, at the Bourtons, Stow on the Wold and Burford, and the upper 

zones are shown to be probably missing again, as around Birdlip, by the discovery 

of ammonites of the bifrons zone a few feet below the Scissum Beds near 

Stow on the Wold. 4 

Towards the Evenlode Valley further diminution in thickness reduces the 

Upper Lias to about 30-40 ft. at Chipping Norton, 20 ft. at Milton under 

Wychwood, 5-12 ft. at Fawler, near Charlbury, and 14 ft. under Oxford 

(proved in a boring at Wytham). The most reduced representation of the 

Upper Lias is to be seen in the old Marlstone workings at Fawler, where little 

but an unfossiliferous clay-band, 5-12 ft. thick, separates the ironstone from 

an attenuated representative of the Inferior Oolite. Nearly all the Whitbian 

zone-fossils are present at the base of the clay, in a thin layer of earthy limestone 

crowded with ammonites. 5 In a railway-cutting near Bloxham Railway 

Station, on the west side of the Cherwell Valley, the acutum, tenuicostatum and 

exaratum subzones appear to be absent. A thin bed of limestone of falcifer 

date was found welded to the top of the Marlstone, above which followed 

clays of the bifrons zone, yielding Frechiella subcarinata. This locality lies 

some distance to the north of Fawler, and the total thickness of Upper Lias 

clay is 70 ft. 6 (see discussion on pp. 66-7 above). 

1 C. Upton, 1906, Proc. Cots. N.F.C., vol. xv, pp. 201-7. 

2 For revised list of fossils see Richardson, 1929, loc. cit., pp. 32-3. 

3 See below, p. 179. 


5 W. J. Sollas, 1926, in Nat. Hist. Oxford District, p. 35; and J.R.B.y 1893, p. 268. 

6 L. Richardson, 1921, Geol. Mag., vol. Iviii, pp. 426-7.

168 THE LIAS 

V. THE MIDLANDS: OXFORDSHIRE TO THE HUMBER 

Beyond the Vale of Moreton Axis and the Oxfordshire shallows another 

great change comes over the Upper Lias. On the South Coast and through 

the West Country the Yeovilian has played the most important part, the 

Whitbian being generally represented by only a few feet of strata. From 

now onwards to the coast of Yorkshire the Whitbian assumes the leading 

role, so that Upper Lias becomes virtually synonymous with Whitbian. In 

short, the Upper Lias north and east of the Vale of Moreton Axis is older than 

the bulk of that to the south and west. Moreover, towards the north successively 

lower zones thicken at the expense of the higher. In the Midlands, 

especially in Northamptonshire, the bifrons zone increased in thickness to 

about 150 ft., and it has been found necessary to divide it into three subzones, 

subcarinatum, fibulatum, and braunianum (from below upwards). Of the total 

thickness, the lowest subzone, that of Frechiella subcarinata, occupies only 

5 ft. in Northamptonshire, while the falcifer and tenuicostatum zones below 

are together only 6-8 ft. thick. In South Lincolnshire the subcarinatum 

subzone thickens to 51 ft. in the Grantham district, while the falcifer and 

tenuicostatum zones together expand to 40 ft. Still farther north, at Lincoln, 

the tenuicostatum zone alone is more than 18 ft. thick, while in Yorkshire it 

reaches 30 ft. 1 

The Midland outcrop, therefore, well illustrates a principle pointed out by 

Buckman in 1910, that during the deposition of the Upper Lias the belt of 

maximum sedimentation migrated southward from Yorkshire towards Dorset. 

'Owing to this migration of the area of maximum deposit', he wrote, 'it happens 

that the strata of the Toarcian in any one English locality do not much exceed 

250 ft. in thickness, and are often far less; yet the amount of work done in 

deposition during that time is equal to 850 ft. or more'. 2 Eight years later 

Prof. Trueman published the results of a detailed examination of the Lias of 

South Lincolnshire, and now, by comparison with Mr. Beeby Thompson's 

accounts of the Northamptonshire Lias, the zones can be followed across the 

Midlands in considerable detail. 

Whatever may have been the nature of the earth-movements causing this 

migration of the area of sedimentation, the results were considerably affected 

by the uplifts along certain established axes, of which the principal were those 

of Market Weighton and of the Vale of Moreton with its adjoining 'Oxfordshire 

shallows'. This is apparent from the over-all thicknesses: the 12 ft. 

of clay and the thin fossil bed at Fawler thicken rapidly to 50-70 ft. of clays 

in the Banbury district (70 ft. at Bloxham), and to as much as 200 ft. in 

Northamptonshire, Leicestershire and Rutland (average 180 ft. inNorthants, 

176 ft. in a boring at Oakham, Rutland). 3 In Lincolnshire they thin down 

to about 120 ft. in the south of the county, around Grantham, but were 

proved to be 199 ft. thick again 8 miles north of Grantham, in a boring 

at Caythorpe. 4 In the next 14 miles from Caythorpe to Lincoln there is a 

rapid diminution to 100 ft. at Lincoln, and the tendency is continued until 

1 A. E. Trueman, 1918, Geol. Mag. [6], vol. v, pp. 103-11. 

2 S. S. Buckman, 1910, Q.J.G.S., vol. lxvi, p. 88. 

3 H. B. Woodward, 1893, J.R.B., Pp. 272, 284, &c. 

4 H. Pre6ton, 1903, Q.J.G.S., vol. lix,pp, 29-32.

UPPER LIAS: MIDLANDS 177 

only 50 ft. remains at Appleby and from 50 ft. to 25 ft. between Appleby and 

the Humber. 1 

Eastward, under Norfolk (Southery), and south-eastward, under Buckinghamshire 

(Calvert), borings have proved that the Upper Lias is completely 

overstepped by younger rocks. Early stages of this overstep are to be seen 

all along the Midland outcrop, where numerous remanie fossils and waterworn 

pebbles of Upper Lias claystone are embedded in the base of the 

Inferior Oolite. Prof. Trueman has pictured diagrammatically (fig. 1) the 

unconformable relations between the Upper Lias and Inferior Oolite from 

Northampton to Lincoln, and it appears that the unconformity becomes 

accentuated towards the Market Weighton Axis. 

NORTHAMPTON GRANTHAM LINCOLN 

FIG. 31. Diagram showing the overstep of the Upper Lias by the basal Inferior Oolite 

(Northampton Sands) in Northants and Lincolnshire. (After Trueman, Geol. Mag.} 

1918, p. no; redrawn). (Not to scale.) 

In consequence of this, the highest beds of the Whitbian are preserved in 

Northamptonshire, where the subzone of Lillia lilli has been detected by 

Beeby Thompson; he believes also that there may be some deposit of variabilis 

date, completing the Whitbian. The lilli beds are overstepped somewhere 

between Northampton and Grantham, and northwards the Inferior Oolite 

rests on successively lower horizons of the greatly expanded bifrons zone, 

until at Roxby, in North Lincolnshire, it comes into direct contact with the 

falcifer zone. 

The higher clays preserved in Northamptonshire, belonging to the highest 

or braunianum subzone of the bifrons zone and to the lowest part of the 

jurensis zone, are especially characterized by the abundance of a small lamellibranch, 

Nuculana [= Leda] ovum. 

Between the Upper Lias and the Middle Lias Marlstone is a Transition 

Bed with a special ammonite, Tiltonoceras acutum, associated with the earliest 

fine-ribbed Dactyliocerates of the tenuicostatum zone. 

SUMMARY OF THE UPPER LIAS, NORTHANTS—LINCOLNSHIRE 2 

Jurensis Zone, 13-24 ft. (Northants only). 

?Variabilis, lilli subzones: UPPER Nuculana ovum CLAYS (24 ft. west of 

Northampton, thinning towards the north-east). These comprise micaceous 

sandy clays, with clay-balls or nodules containing a peculiar assemblage of 

1 W. A. E. Ussher, 1890, 'Geol. North Lines.', Mem. Geol. Surv., p. 55. 

2 A. E. Trueman, 1918, Geol. Mag. [6], vol. v, pp. 103-11; and B. Thompson, 1910, 

Geol. in the Field, pp. 461-8.

168 THE LIAS 

fossils. A rolled specimen of Lillia lilli occurred at Moulton, from which 

Beeby Thompson infers that the age of the clays may be as late as variabilis 

date. At the base is a layer of waterworn, scratched, bleached nodules, overgrown 

with oysters and Serpulce. 

Bifrons Zone, 150 ft. thick in Northants. 

Braunianum subzone: MIDDLE AND LOWER Nuculana ovum CLAYS, 70 ft. 

The Middle Clays are the chief repository of N. ovum, and belemnites are 

also abundant. In the Lower Clays small gastropods abound, particularly 

Cerithium armatum, together with Dactylioceras commune, D. crassum, Phylloceras 

heterophyllumy See. The subzone is overstepped probably not far from 

the northern boundary of Northamptonshire. 

Fibulatum subzone: This consists in Northants of a poorly fossiliferous 

clay, up to 76 ft. in thickness, containing towards the top pyritized ammonites, 

especially P. fibulatum, D. commune and H. bifrons. Although Beeby Thompson 

declares that in Northants the subzone lies below the range of Nuculana 

ovum, Trueman assigns 23 ft. of beds to it at Grantham containing N. ovum 

abundantly in pockets, and he considers that the subzone should include the 

Lower Nuculana ovum Beds of Northamptonshire. 1 At Grantham Trueman 

records Peronoceras cf. attenuatum, Phylloceras heterophyllum, Porpoceras 

vortex, &c. The subzone is probably overstepped completely by the Inferior 

Oolite not far north of Grantham. 

Subcarinatum subzone: In Northants this comprises only 5 ft. of strata, 

consisting of calcareous clay with numerous small, white concretions and some 

larger nodules containing immense numbers of Dactyliocerate ammonites, and 

at the top an exceptionally constant hard band (9-18 in.) full of ammonites: 2 

the most conspicuous are D. commune and H. bifrons (abundant), and Frechiella 

subcarinata (rare). In the Grantham district, S. Lines., the subzone 

has expanded according to Trueman to 51 ft. of grey shale with scattered 

nodules and with 1 ft. of dark earthy limestone about the middle. He records 

the same ammonites as those found in Northants, with additions, especially 

Harpoceras aff. mulgravium in the lower part. 

Falcifer Zone, 6-8 ft. in Northants, 25 ft. in S. Lines. 

Falcifer subzone: In Northants all that can be said to belong to this subzone 

is some 4-5 ft. of marly clay and at the top a hard band, often oolitic, with 

large Harpocerates of the falcifer group. About Grantham Trueman assigns to 

it 9 ft. of grey shale with nodules, and at the top a 6-in. band of rubbly, 

ferruginous limestone, also with scattered ooliths, and containing many 

ammonites: Harpoceras aff. falcifer, H. mulgravium, Dactyliocerates, and 

Harpoceratoides ovatum (Young and Bird), which occurs at the same level also 

in Yorkshire. 

Exaratum subzone: In Northants Beeby Thompson has recorded Harpoceras 

exaratum at Bugbrooke in an 8-in. band of hard limestone, w r hich he 

1 Compare B. Thompson, 1910, Geology in the Field, p. 462, and A. E. Trueman, 1918, 

Geol. Mag., p. 107. 

2 B. Thompson called this the Upper Cephalopod Bed and that in the falcifer subzone the 

Lower Cephalopod Bed, names which ought to be dropped as they may lead to confusion with 

the Upper Lias Cephalopod Bed of the Cotswolds.

UPPER LIAS: MIDLANDS 179 

calls the Inconstant Cephalopod Bed. Trueman assigns 15 ft. of grey shales 

with blue limestone nodules to the zone at Grantham, S. Lines., where he 

records the index fossil, with Dactylioceras vermis and Elegantuliceras elegantulum. 

Tenuicostatum Zone, up to 15 ft. 

Tenuicostatum subzone: Throughout the area this subzone consists of 

paper-shales with fish-remains, lithologically identical with the paper-shales 

and Leptcena Bed of Dumbleton and the North Cotswolds, which lie below the 

Saurian and Fish Bed (? of exaratum date). In Northants (e.g. at Bugbrooke) 

the thickness is from 9 in. to a little over 1 ft., but at Grantham and Lincoln 

it is as much as 15 ft. At Bracebridge Brick Pit, 3 miles south of Lincoln 

Cathedral, where the 15 ft. of paper-shales with layers of nodules are the 

highest beds exposed, Trueman has found them to contain Dactylioceras cf. 

tenuicostatum and D. semicelatum, both characteristic fossils of the Grey 

Shales (tenuicostatum zone) of Yorkshire. A date is thus arrived at for the 

paper-shales of Dumbleton and the Leptcena Bed of Dumbleton and Ilminster. 

Acutum subzone: The acutum subzone is present in three areas, forming a 

Transition Bed between the Marlstone and the Upper Lias: namely, on the 

Oxon.-Northants border; about Tilton, in Leicestershire; and in the Lincoln 

district. In between, the succeeding zones cut down into the Middle Lias 

and in certain places (as about 4 miles south-east of Tilton) the Marlstone has 

been completely removed. 

In the two southerly areas the Transition Bed is merely a thin seam, a few 

inches thick, more or less joined to the top of the Marlstone, and it contains an 

admixture of ammonites, especially Dactyliocerates and Tiltonoceras acutum. 1 

At Lincoln it consists of 2I- to 3 ft. of greenish and grey shale, the lower part 

passing in one pit into a sandstone, and, although the fine-ribbed Dactyliocerates 

occur throughout, T. acutum appears only in the highest layer. 'Thus 

we must either conclude', writes Prof. Trueman, 'that only the upper portion 

of the Transition Bed of Lincoln is homotaxial with the Transition Bed of the 

Midlands, or else that T. acutum did not arrive in the Lincoln area until 

later.' 2 

VI. THE MARKET WEIGHTON AXIS* 

The northerly attenuation of the Upper Lias observed throughout Lincolnshire 

is continued north of the Humber, where, after narrowing greatly for 

about 5 miles, the outcrop disappears beneath the Chalk at Sancton near 

Market Weighton, not to reappear for 13 miles to Kirby Underdale. W T here 

last seen, the Upper Lias is from 20-35 ft. thick. At Roxby, 4 miles south of 

the Humber, the Inferior Oolite has been proved to rest directly on the 

falcifer zone. It is not known whether the overstep becomes any greater over 

the axis, but although the clays are not adequately exposed north of the 

Humber, evidence for the falcifer zone has been obtained in field rubble and 

ditches. 

1 B. Thompson, 1892, Rept. Brit. Assoc. for 1891, pp. 334-51; and E. Wilson and W. D. 

Crick, 1889, Geol. Mag. [3], vol. vi, pp. 296-305. 

2 A. E. Trueman, 1918, GeoL Mag. [6], vol. v, p. 106. 

3 C. Fox-Strangways, 1892,J.R.B.} pp. 141-4.

168 THE LIAS 


The Upper Lias reappears from beneath the Chalk 3 miles before the first 

signs of the Middle Lias, and thickens rapidly north of the Derwent to 80 ft. 

at Crayke, 100 ft. at Coxwold, 160 ft. at Swainby Mines and 200 ft. round the 

northern rim of the Yorkshire Basin. All the way it consists of dark shales 

and clays, overlain non-sequentially by the Dogger, or basal bed of the 

Inferior Oolite (scissum-murchisonce zones), which has in places cut deep 

channels into it. Nearly everywhere the shales on which the Dogger rests are 

of Whitbian age, but recent discoveries by Mr. W. E. F. Macmillan of ammonites 

of the striatulum and dispansum subzones on Danby High Moor, north 

of the Esk Valley, over an area 3\ miles long by 2 miles wide, show that at least 

locally the Yeovilian is represented. 1 

Only in the most south-easterly exposure in the Yorkshire Basin, on the 

coast from Blea Wyke Point to Ravenscar (Peak), are the uppermost Whitbian 

and Yeovilian beds as a rule fully developed. The Yeovilian there takes on a 

sandy facies, comparable in lithic character and in age with the Midford 

Sands. 

At Peak, below the Ravenscar Hotel, a fault with a throw of some 400 ft. 

brings down Lower Estuarine Series (Inferior Oolite) against Middle Lias. 

South and east of the fault for about a mile along the cliffs, which here rise 

to a great height above the sea, the Yeovilian sandstones, sands and sandy 

shales, dipping southward, succeed the Whitbian to a thickness of 150 ft., 

and are overlain by the Dogger, or basal bed of the Inferior Oolite. North 

and west of the fault the whole of these Yeovilian strata are absent, together 

with the highest part (perhaps 60 ft.) of the W T hitbian; so that the Dogger, 

after crossing the fault and being thrown some 200 ft. by it, comes to rest 

directly on the channelled surface of the Whitbian. Northward, in the direction 

of Whitby, the general dip is slightly to the north, and higher horizons 

of the Whitbian gradually make their appearance again below the Dogger. 2 

These facts point to an anticline having arisen north-west of the Peak Fault 

and to the initiation of a fracture before the end of the Whitbian period. Most 

of those who have studied the localization of the highest Whitbian and the 

whole of the Yeovilian strata on the downthrown side have agreed that when 

these deposits were being formed the Peak Fault must have been already in 

existence; in fact, that the beds were banked against the gradually rising fault 

scarp, while denudation proceeded upon the upthrown side. It can definitely 

be said that there was faulting before the deposition of the Dogger, for 

while the Dogger can be seen to be thrown only some 200 ft., measurements 

show that the base of the Upper Lias has been thrown at least 400 ft. In 

respect of the evidence which it provides for faulting as well as folding in 

England during Jurassic times, the Peak Fault is thus unique. 

Another point of interest is that the ends of the downthrows strata are bent 

down towards the slide plane, while the ends of the upthrown strata curve 

upward. This is the opposite of the usual arrangement. It has been explained 

by Dr. Rastall as due to a slight final movement in the reverse direction, 3 but 

1 W. E. F. Macmillan, 1925-31, The Naturalist, 1925, pp. 236, 316; 1926, pp. 51-3; 1931, 

p. 345. Since going to press Dumortierice and opalinum horizons have been recorded: see Proc. 

Yorks. Geol. Soc., 1932, N.S., vol. xxii, p. 122. 

2 See R. H. Rastall, 1905, Q.J.G.S., vol. Ixi, pp. 441-60. 3 Ibid., p. 448.

UPPER LIAS: YORKSHIRE BASIN 181 

others, particularly Prof. Kendall, regard it as a survival of the original 

anticlinal or monoclinal structure ('the preliminary kink') imposed on the 

strata before (and as a consequence of which) the fracture took place. 1 

Palaeontologically the Blea Wyke Yeovilian strata (BLEA WYKE BEDS) are 

on the horizon of the Down Cliff Clay of Dorset and the gap beneath it, 

namely the Dumortierice and dispansum subzones. The Bridport Sands may, 

however, be represented in some parts of Yorkshire (see note i on p. 180). 

The Yorkshire Upper Lias Clay contains representatives of all the zones and 

most of the subzones of the Whitbian, of which it furnishes the type sections 

around Whitby. Many of the fine exposures are due to exploitation of what 

were once two commercially valuable products, alum and jet. The alum 

industry flourished in the eighteenth century, and the series of enormous 

workings along the outcrop testify to its magnitude. It was killed by the discovery 

of a cheaper means of production from the shales of the Coal Measures. 2 

The jet industry 3 reached its zenith in the nineteenth century, the production 

for the peak year 1873 realizing £90,000. Its decline was rapid, however, 

owing to the change of fashion and to the importation of inferior but cheaper 

jet from abroad, chiefly from Germany and Spain. 

SUMMARY OF THE UPPER LIAS OF THE YORKSHIRE COAST (RAVENSCAR, WHITBY 

AND HAWSKER DISTRICT) 4 (Plate VII) 

YEOVILIAN 

Jurensis Zone: BLEA WYKE BEDS, 100 ft.: these are divided into Yellow 

Beds above and Grey Beds below. The YELLOW BEDS consist of even-bedded 

yellow sandstones, 53 ft. thick. The highest 25 ft. were formerly classed with 

the Inferior Oolite, but were transferred to the Lias by Dr. Rastall (who has 

been followed by subsequent writers): they are unfossiliferous. Below comes 

a fossil-bed full of Terebratula trilineata auctt., and in the lowest 25 ft. of the 

Yellow Beds several species of Dumortierice have been found (D. munieri 

Haug at the top, D. externicostata Branco sp., D. aff. multicostata Buck.), 

together with Pseudolioceras cf. gradatum Buck, and numerous Homoeorhynchia 

cynocephala. The ammonites assign at least the lower half of the 

Yellow Beds to the Dumortierice subzone, although in the South of England 

.the Homoeorhynchia is later. The GREY BEDS consist of 35 ft. of grey sandstones 

overlying 7 ft. of soft grey shale. Lingula beani Phil, occurs throughout, 

and there are many Serpulce in the highest 10 ft., from which the names 

Serpula Beds and Lingula Beds have been given them. The ammonites 

indicate that the Grey Beds belong to the dispansum subzone: P. dispansum, 

Hudlestonia affinis, H. wykiensis and species of Pseudolioceras have been 

recorded. The Blea Wyke Beds contain two special Crustaceans not yet found 

elsewhere, Glyphceaprestwichi Woods and Eryma birdi (Bean). 5 

STRIATULUM SHALES. Below the Blea Wyke Beds are 60 ft. of darker grey 

1 P. F. Kendall and H. E. Wroot, 1924, Geol. Yorkshire, pp. 249-50. 

2 See account in Kendall and Wroot, 1924, ibid., pp. 358-63. 

3 Account in Fox-Strangways, 1892,J.R.B., pp. 455-9. 

4 Based on R. H. Rastall, 1905, loc. cit.; C. Fox-Strangways and S. S. Buckman, 1915, 

"Geol. Whitby and Scarborough', 2nd ed.,pp. 15-22,75-83; L. Richardson, 1911, Proc. Yorks. 

Geol. Soc., N.S., vol. xvii, pp. 188-9; an d S. S. Buckman 1911, ibid., pp. 209-12. 

5 H. Woods, 'Mon. Mac. Crust.', Pal. Soc., pp. 51, 74.

168 THE LIAS 

argillaceous shale, full of spangles of white mica; they yield Grammoceras 

striatulum, G. toarcense and Pseudogrammoceras latescens. 

That these Yeovilian zones are not entirely unrepresented in the area on the 

upthrown side of the Peak Fault is shown by the discoveries of Mr. Macmillan, 

already mentioned. At Danby Dale and Fryup he found Phlyseogrammoceras, 

Hudlestonia and Grammoceras high up on the shale slopes. At one place the 

ammonites were described as occurring in a 'nest' 10 ft. below the Dogger, and 

evidently not derived. These occurrences lie about 20 miles west of the 

Peak Fault. 

WHITBIAN 

PEAK SHALES. Below the Striatulum Shales is an unknown thickness of 

shales which have yielded species of Haugia. Hudleston described them as 

60 ft. in thickness, but the exposures are badly concealed by scree and slips 

and they are involved in a good deal of uncertainty. Buckman named them 

the Peak Shales. They are the lowest of those beds which at the coast occur 

only on the east side of the Peak Fault. 

Bifrons Zone: ALUM SHALE SERIES, 90 ft. The Alum Shales are grey and 

crumbling and highly charged with disseminated pyrites. The highest 20 ft. 

are often known as the Cement Shales on account of their containing lines of 

nodules formerly made into cement. From this division, excavated in the 

alum works, most of the rich vertebrate fauna of the Upper Lias has been 

obtained. Whole skeletons of many of the large saurians were extracted from 

the workings, and the study of their remains has greatly advanced our know T - 

ledge of the Upper Liassic vertebrate fauna. The Reptilia found on the 

Yorkshire coast comprise three species of Plesiosaurus, five of Ichthyosaurus, 

four of Steneosaurusy three of Thaumatosaurus, two of Pelagosaurus, and one 

each of Sthenarosaurus and Scaphognathus. There are also some sixteen 

species of fish of all the usual Liassic genera. 

The main mass of the Alum Shales is characterized by ammonites of the 

bifrons zone: Hildoceras aff. hildense, Dactylioceras commune, D. aff. holandrei, 

&c., together with large quantities of Nuculana ovum, as in the Midlands. The 

basal band of the bifrons zone is a double line of pyritous doggers with masses 

of belemnites and an ammonite peculiar to it: Pseudolioceras pseudovatum 

(with a subzone of its own in the classification of S. S. Buckman). 

Falcifer Zone: JET ROCK SERIES, 90-100 ft. This consists of a mass of dense, 

dark, bituminous shales, characterized by abundant ammonites of the 

Harpoceras mulgravium type, and a certain number of other mollusca, especially 

Inoceramus dubius. Many of the saurians and fish recorded from the Alum 

Shales occur here also. 

The lowest 25-30 ft. constitute the JET ROCK proper, and this, from the 

occurrence of Harpoceras exaratum near the base, Buckman assigned to the 

exaratum subzone. The jet occurs as lumps and lenticles in the hard shale, 

especially towards the top. It is believed to be a product of water-logged wood 

so thoroughly altered that all traces of structure have been obliterated. With it 

occur numerous lines of nodules, usually enclosing fossils filled with bituminous 

cementstone, or even, when the fossils are ammonites, liquid bitumen 

in the gas-chambers. The nodules emit a strong odour of mineral oil when 

broken open.

UPPER LIAS: HEBRIDES 183 

At the top of the true Jet Rock is a line of large-sized nodules of calcareous 

shale, up to 15 ft. in diameter. The band forms a reef at sea on both sides of 

Saltwick, extending eastward, often marked by a line of breakers, until due 

north of Whitby Abbey. 

Tenuicostatum Zone: GREY SHALE SERIES (30 ft.). These, the lowest beds 

of the Upper Lias, are seldom well exposed, owing to the accumulation of 

debris fallen from higher up the cliffs. They consist of somewhat featureless 

grey sandy shales, with nodular earthy limestone bands, in which Dactylioceras 

tenuicostatum occurs. The only other fossils at all common are belemnites. 

VIII. THE HEBRIDEAN AREA 

(a) Skye and Raasay 1 

The Upper Lias has a considerable outcrop across Raasay and on the adjoining 

coast of Trotternish in Skye, and it is also found along the east coast of 

Strathaird, close to the waters of Loch Slapin. It is chiefly remarkable for 

containing an iron ore, which becomes commercially workable in the island 

of Raasay. The rest of the formation consists predominantly of shales, in the 

middle of which the ironstone-band is sandwiched. The ammonites show 

that most of the Yeovilian and the upper part of the Wliitbian Stages are wanting, 

as in Yorkshire north-west of the Peak Fault, while there is a thick 

development of the basal Aalenian as in the Dorset-Somerset area. 

DUN CAAN SHALES, 70 ft. The upper shaly division, above the ironstone, 

belongs to the opalinum zone. It reaches its greatest development of 70 ft. of 

micaceous shales at the foot of Dun Caan in Eastern Raasay (Plates X and XIV). 

In Skye the shales are only some 25 ft. thick, and less micaceous than in Raasay. 

The best exposure in Skye is south of Holm, but the series has been studied 

in detail at Dun Caan, where it is best developed, and the sequence there may 

be taken as typical (fig. 32, p. 184). 

The highest 5 ft., with calcareous nodules and hard bands, which form a 

lithological passage up into the Inferior Oolite, have been identified as the 

opaliniforme subzone. Besides CyphoUoceras opaliniforme, they have yielded 

Pleurolytoceras hircinum (Quenst.), Pseudolioceras beyrichi(Schloenb.), Walkericeras 

subglabrum (S. Buck.), Pleydellia, and belemnites. 

The remaining 65 ft. of the shales represent a much-expanded aalensis 

subzone, and differences detected by Buckman in the ammonites of the 

highest 16 ft. induced him to suggest that that portion should be separated as 

a new subzone of Canavarina venustida. By far the commonest fossils throughout 

are ammonites and belemnites. Pleydellia aalensis occurs sparingly, 

accompanied by P. leura (S. Buck.), Canavarina spp., Walkericeras spp., 

Pleurolytoceras leckenbyi (Lyc.); while most abundant of all are five species of 

Cotteswoldia. The identity of the cephalopod fauna with that of the upper part 

of the Yeovil Sands of the Crewkerne district of Somerset is noteworthy. 

In Strathaird, on the western shore of Loch Slapin, the Yeovil Sands are 

simulated even in lithological features, for the Dun Caan Shales pass into 

current-bedded, coarse, calcareous sands and sandstones, inseparable from 

1 Based on C. B. Wedd, 1910, 'Geol. Glenelg, Lochalsh and SE. Skye', p. 115; and G. W. 

Lee and S. S. Buckman, 1920, 'Mes. Rocks Applecross, Raasay and NE. Skye', pp. 30-43, 

65-7, Mems. Geol. Surv.

168 THE LIAS 

the Inferior Oolite above. In this facies of the beds fossils are much scarcer 

than in the shales of NE. Skye and Raasay. 

Below the Dun Caan Shales is a considerable break, in which the moorei, 

FIG. 32. Section of the Middle and Upper Lias and Inferior 

Oolite in Raasay. After G. W. Lee, 1920, 'Mesozoic Rocks 

of Applecross, Raasay and NE. Skye', Mem. Geol. Surv. 

Dumortierice, dispansum, and struckmanni subzones are so far unaccounted for. 

The palaeontological hiatus proved in Raasay is reflected by an abrupt lithic 

change in Strathaird, Skye, where Wedd noted that 'a knife-blade could 

separate the two lithological divisions'. 1 

1 C. B. Wedd, 1910, loc. cit., p. 115. The arenaceous facies of the Dun Caan Shales (presumably) 

was there treated as Inferior Oolite, in accordance with the practice of the Survey.

UPPER LIAS: RAASAY IRONSTONE 185 

RAASAY IRONSTONE, 2-8 ft. Immediately beneath the stratigraphical break 

just referred to, there is in the Strathaird and the Trotternish districts of 

Skye a 1 ft. 9 in. to 2 ft. band of dark-blue to greenish oolitic ironstone, in 

Strathaird little more than a ferruginous oolitic limestone. In the southern 

part of the Island of Raasay it thickens to 8 ft., at the same time improving 

in quality and the richness of its fauna. Since its discovery by H. B. Woodward 

in 1893 it has been worked as an iron ore, and for its shipment a pier has been 

built at the southern end of the island, connected with the mines by tramway. 

The Raasay Ironstone is very variable in composition. In its original state, 

where the band is thick, it is a dark-green, glossy rock, consisting of green 

ooliths in a clear matrix, the ooliths containing most of the iron in the form of 

a green silicate, probably chamosite. But where the ore is thin, as in Skye and 

the north-east of the Raasay outcrop, the green ooliths have been transformed 

into black oxides and carbonate (predominantly siderite), leaving only traces 

of the silicate. The process of formation of the ore has thus been very different 

from that at one time thought to have accounted for the genesis of oolitic 

ironstones, in w r hich ordinary oolitic limestone is supposed to have been 

replaced by carbonate of iron. There is here a strong indication that the iron 

silicate was an original constituent of the sediment, and modern thought is 

coming to regard this more and more as the normal process of oolitic oreformation. 

Palaeontologically the ironstone is not rich. The upper part of the ore bed 

in the main mine, however, has yielded Hildoceras bifrons (d'Orb. non Brug.) 

which indicates the subcarinatum subzone of the bifrons zone, and mingled 

with it were found certain Dactyliocerates indicating the falcifer zone. Evidence 

recently obtained by the Survey in Ardnamurchan proves that, as was 

suspected from their rolled condition, all these fossils are derived from earlier 

deposits, the date of deposition of the ironstone being striatulum hemera or 

later. 

PORTREE SHALES, 3-78 ft.: The rest of the Upper Lias, the portion lying 

beneath the Raasay Ironstone, displays an extraordinary variability in thickness. 

Near Portree, the capital of Skye, from which the beds take their name, 

they consist of dark, micaceous, soft shales with occasional hard bands and 

limestone nodules. The thickness at the type locality is 48 ft; farther north 

along the coast of Trotternish a boring at Bearreraig Bay proved 78 ft.; and 

in S. Skye, on the peninsula of Strathaird, the thickness is only 20 ft. A still 

greater diminution takes place in Raasay, where the shales are reduced to 

9 ft. or less—in places even 3 ft. The presence of the rolled fossils in the 

overlying ironstone shows that the diminution is due at least in part to 

intraformational erosion. 

In Skye the Portree Shales, although so thick, are less satisfactorily exposed 

than in Raasay. It has been ascertained, however, that the falcifer and 

exaratum subzones are normally represented. The bulk of the shales, down to 

within 16 ft. of the base, yield numerous Dactyliocerates and Harpocerates 

of the falcifer subzone. Below this Harpoceras aff. exaratum comes in for a 

few feet. Of the lowest level of all, nothing is yet known. 

On the horizon of i/. aff. exaratum, 14 ft. from the base of the shales near 

Holm, north of Portree, is a thin band of jet. The associated ammonites prove 

it to be on the same horizon as the Jet Rock of Yorkshire, a correspondence of

168 THE LIAS 

a highly abnormal feature that is truly remarkable in two localities so distant 

as Whitby and Skye. 

In Raasay the thin representatives of the Portree Shales are very fossiliferous, 

abounding in Dactyliocerate ammonites of at least ten species, of 

which the most abundant is D. delicatum, as well as in belemnites (Megateuthis 

and Dactyloteuthis spp.). Although both the falcifer and exaratum subzones 

are evidently represented, they have not been satisfactorily separated. 

The tenuicostatum zone has been detected in Raasay in the uppermost 6 ft. 

of the underlying Scalpa Sandstone, developed in a facies identical with the 

beds that a few feet lower yield Paltopleuroceras spinatum. The lithological 

continuity of the tenuicostatum zone with the Middle Lias thus provides a 

parallel between these distant islands and the Cotswolds. 

(b) Mull and Ardnamurchan 1 

Small patches of Upper Lias occur in Mull in three localities: about Loch 

Don; between Loch Spelve and Loch Buie; and near Carsaig. On the neighbouring 

mainland there is a fourth patch near Kilchoan, on the south side of 

the promontory of Ardnamurchan (see map, p. 114). All these sections have 

been described in recent memoirs by the Geological Survey of Scotland. 

DUN CAAN SHALES i The most complete sections are in the Loch Don district, 

at Port nam Marbh, where the passage to the Inferior Oolite is seen, but 

unfortunately the Dun Caan Shales here prove scantily fossiliferous and no 

ammonites have been obtained. CyphoUoceras was, however, found at the base 

of the Inferior Oolite section in Ardnadrochet Glen, thus proving the presence 

of the opaliniforme subzone. The beds, like their counterparts in the northern 

islands, consist of sandy shales and sandy limestones. In Ardnamurchan the 

opaliniforme subzone was not detected, but a gap was filled by the recognition 

of both the aalensis and the moorei faunas, neither of which has been detected 

in Mull. The aalensis subzone is reduced to 5 ft. in thickness. The ammonites 

were obtained from the upper part of a bed of hard sandy flags on the beach 

near Kilchoan, and they were identified by Buckman as cf. Pleydellia aalensis 

(Ziet.), cf. P.fluens S.Buck., }Cotteswoldia and Canavarinasp. The moorei fauna 

is not known at any other point in Scotland. It was discovered by the Survey 

in the lower part of the same bed of flags as that yielding the aalensis fauna, 

and separated from the Raasay Ironstone by an intrusive dyke. The ammonites 

identified by Buckman were Dumortieria cf. brancoi S.Buck., D. ? exacta 

S.Buck. and D. cf. tsubexcentrica S.Buck. 

RAASAY IRONSTONE : On the shore in the west side of Kilchoan Bay, Ardnamurchan, 

the Survey have recognized the Raasay Ironstone as a 4-ft. band of 

bluish ferruginous stone, largely made up of compacted ooliths; the same 

band also crops out a mile farther west, where it is much baked by the 

Tertiary gabbro. From the first locality they collected ammonites referred to 

Grammoceras aff. penestriatulum S.B., G. aff. toardense (d'Orb.), Alocolytoceras 

cf. perlceve (Denckm.) and Dactylioceras cf. holandrei (d'Orb.), together with 

belemnites. The deposit is therefore at least as late in date as the striatulum 

subzone, while the Dactyliocerates are derived, as in Raasay, from the mucheroded 

Portree Shales beneath. Before the discovery of these striatulum 

1 Based on G. W. Lee, 1925, Tre-Tert. Geol. Mull, Loch Aline and Oban', pp. 95-112; 

and G. W. Lee and J. E. Richey, 1930, 'Geol. Ardnamurchan', pp. 43-8; Mems. Geol. Surv.

UPPER LIAS: KENT 187 

ammonites it was thought, on the evidence obtained in Raasay, that the chief 

stratigraphical gap lay above the ironstone, but now it seems more probable 

that it lies mainly below. More intensive collecting may eventually reveal 

faunas of struckmanni or dispansum dates in the ironstone; but even the evidence 

now available shows that the ironstone is Yeovilian. 

PORTREE SHALES : The thickest development of the Portree Shales occurs at 

Port nam Marbh, where the blue shales are 30 ft. thick and very poorly 

fossiliferous. The Survey obtained two Dactyliocerates and a Harpocerate, 

indicative of the falcifer zone. The other exposures in Mull are both small 

and fragmentary. In a small patch at Carsaig, however, fossils are more 

numerous. The Survey collected some seventeen species of ammonites from 

two horizons; those from the upper horizon were said by Buckman to indicate 

the bifrons zone and those from the lower the falcifer zone. Associated with the 

lower assemblage of ammonites were fish-remains, Inoceramus dubius and a 

small unidentified gastropod said to occur in the Fish Bed and paper-shales 

of the English Midlands. 

In Ardnamurchan the thickness of the Portree Shales is about 20 ft. £ The 

black shales occur in lenticular masses, a few yards long, amongst a complex 

of basic cone-sheets and sills' 1 on the shore in the west side of Kilchoan Bay, 

where the ironstone crops out, and also in the second exposure a mile farther 

west. They yielded to the Survey a considerable assemblage of Dactyliocerates 

and Harpocerates of the falcifer zone. 


The Upper and Middle Lias, with the Inferior Oolite, are faulted down 

out of sight in East Sutherland. The only evidence for the occurrence of 

Upper Lias on the east coast of Scotland is a specimen of Frechiella subcarinata 

in the Hugh Miller collection, said to have been found at Shandwick, 

Ross-shire (in Drift?). 2 

X. KENT 3 

The Upper Lias, like the Middle and Lower Divisions in Kent, is thickest 

in the south-westerly borings and thins to the north and north-east, being 

overstepped by the Lower Oolites approximately along the line of the Dover- 

Canterbury railway. That the discordance between the Upper Lias and the 

overlying beds is more in the nature of an overstep than an overlap is shown 

by the absence of the Yeovilian strata, as in the Midlands and Lincolnshire. 

The Kentish Upper Lias is exclusively Whitbian, excepting possibly at the 

single locality of Brabourne, where, in one of the two most south-westerly of 

all the borings, a single Grammoceras was found, which was considered by 

Buckman to indicate the presence of the striatulum subzone. Evidence was 

insufficient to enable it to be gauged how complete the succession below that 

level might be, the next highest ammonites detected anywhere in Kent being 

of bifrons date. 

The greater part of the Kentish Whitbian consists of clay, sometimes green, 

sometimes brown, either shaly, silty, or lumpy, and belonging to the bifrons 

1 J. E. Richey, 1930, loc. cit., p. 43. 

2 G. W. Lee, 1925, 'Geol. Golspie', p. 74, Mem. Geol. Surv. 

3 Based on G. W. Lamplugh and F. L. Kitchin, 1911, loc. cit.; and Lamplugh, Kitchin 

and Pringle, 1923, loc. cit. 

S.J4371 O

188 T H E LIAS 

and earlier zones. It yields numerous Dactyliocerates of the bifrons zone in 

the highest 8 ft. at Elham and on a corresponding horizon at Brabourne; also 

Hildoceras walcotti (Sow.), Peronoceras and Porpoceras: these indicate the 

subcarinatum and fibulatum subzones. At Elham, Bishopsbourne and Folkestone 

the falcifer subzone was the highest encountered; this yielded Harpoceras 

mulgravium (Young and Bird), Hildoceras levisoni (Simps.) and other 

species. Beneath it, and forming the top of the Upper Lias at Dover and 

Ropersole, was recognized the exaratum subzone, with Harpocerates of the 

exaratum type, Dactylioceras delicatum (Phil.) and a number of other fossils, 

the most distinctive being a carinate Corbula. Finally, the tenuicostatum zone 

was easily differentiated by means of its numerous delicately-ribbed Dactyliocerates 

from the underlying spinatum beds, with which it was generally found 

to be in lithological continuity. Unlike the rest of the Upper Lias it is typically 

developed as a grey sandy limestone, up to 8 ft. in thickness. 

The northerly and north-easterly attenuation is rapid, the thickness of the 

Upper Lias falling from 41 ft. at Elham and 55 ft. at Folkestone to 8f ft. at 

Dover and 4 ft. at Chilton, where it is represented only by the tenuicostatum 

zone.

CHAPTER VIII 

LOWER AND MIDDLE INFERIOR OOLITE 

Stages. Zones (Plates XXXIII-IV). Strata in the Cotswolds. 

£ < 

0 

0 

1—» 

< 

W 

§ 

i 

S 

PH 

QUI 

2 

VESULIAN TRANSGRESSION 

Teloceras blagdeni 1 Absent from the Cotswolds 

W 

H Otoites sauzei SSSTBS'I'Sleeve Hill 

W O 

•J 0 

§ § Witchellia spp. j 

Witchellia Grit 

Notgrove Freestone 

Shirbuirnia spp. 2 ! Gryphite Grit 

g i 

W 

H 

J 

3 O 

§ « 

0 2 

g 

Hyperlioceras discites 3 | 

Ludwigella concava 

Brasilia bradfordensis 

Ludzoigia murchisonce 

BAJOCIAN TRANSGRESSION 

Buckmani Grit 

Lower Trigonia Grit 

Tilestone 

Snowshill Clay 

Harford Sands 

Upper Freestone 

Oolite Marl 

Lower Freestone 

Pea Grit 

Ancolioceras spp. 4 Lower Limestones 

Tmetoceras scissum Scissum Beds 


IN Dorset and Somerset the Lower and Middle Inferior Oolite are much 

condensed. The zones that are present are but thin representatives of considerable 

thicknesses of strata elsewhere, while some are to be detected only 

by their fossils, water-worn and bored, redeposited in conglomerates. In 

Somerset, over wide areas, the rocks are absent altogether, Upper Inferior 

Oolite resting directly upon Upper Lias. 

In consequence of this attenuation, when the Dorset-Somerset area is 

viewed without reference to other districts, the impression is gained that 

palaeontologists have greatly overloaded the formation with unnecessarily 

1 Formerly humphriesiani, in Buckman's earlier papers. The zone has been subdivided in 

Germany. 

2 Formerly Sonninice, but renamed by Buckman, 1910, Q.J.G.S., vol. lxvi, p. 78, on account 

of generic rearrangement of the Sonninice. True Sonninice are said to occur only in the sauzei 

zone. 

3 Certain deposits above those containing H. discites were dated by Buckman as postdiscites. 

Such deposits, where they occur, will here be treated as part of the discites zone. 

4 Founded by Buckman, 1910, loc. cit., p. 79, for certain thin Dorset strata, and now 

propagated in the literature by Richardson and subsequent workers. No ammonites have 

been found in the Lower Limestones of the Cotswolds, but Ancolioceras has been obtained 

from the Variable Beds of the Northampton Sands, which are on about the same stratigraphical 

horizon.

i9o LOWER OOLITES 

minute zonal subdivisions. But when the Cotswolds are considered, where 

the same rocks thicken to nearly 300 ft., their value becomes more apparent. 

The nature of the zones in use in the Inferior Oolite is of considerable 

theoretical interest. Most of them are true faunizones, because they are characterized 

by a special fauna—a whole assemblage of molluscs and brachiopods, 

the species of which may or may not occur above or below, but which are 

never assembled in the same proportions outside their particular zone. Over 

wide tracts of country, therefore, the zones have been traced by means of their 

general faunal assemblage, often c the discovery of the index-species of 

ammonite. On the other hand, they were in the first place founded, and ultimately 

depend, upon the local acmes of certain ammonites selected as indexspecies. 

They are therefore epiboles. It may be said, in fact, that in Dorset 

and Somerset, where ammonites abound, the zones are treated as epiboles, 

while in the Cotswolds and the Lincolnshire Limestone areas, where ammonites 

are not autochthonous and are rarely met with, the same divisions have 

to be treated as pure faunizones (see Chapter I, pp. 34-5). Meanwhile the 

divisions will be here spoken of simply as 'zones', and the corresponding timeunits, 

in accordance with the universal practice in the literature of this formation, 

as 'hemerae', this term taking priority over 'secule' where the two units 

happen to be identical. 

(a) Burton Bradstock to Crewkerne 1 

On the coast the whole of the Inferior Oolite is only 11 ft. thick, forming 

a capping to the cliffs of Bridport Sands on either side of the mouth of the 

River Bredy, between Bridport Harbour and Burton Bradstock (Plate VI). 

Large blocks of this capping have fallen on the beach, where they have formed 

a collectors' paradise for many years. Six and a half feet of the total thickness 

belong to the Upper Inferior Oolite, leaving only 4J ft. to be considered 

here (figs. 33 and 29, p. 154). 

The bulk of the \\ ft. is taken up by the Middle Division, from the discites 

zone upwards, which is represented by the RED BED, 2 ft. 10 in. thick. The 

top of the Red Bed is water-worn and pitted, and on it here and there rest 

patches of conglomerate, largely made up of fragments derived from its 

destruction elsewhere. The Red Bed contains three distinct layers, all of 

which may be recognized in the conglomerate. Among the pebbles of the 

conglomerate have also been found ammonites (for the most part rolled) 

identified by Dr. Spath as denoting probably niortensis, blagdeni and sauzei 

zones. Thus somewhere in the district the whole of the Red Bed or local 

Middle Inferior Oolite seems to have been broken up and eroded immediately 

before the deposition of the garantiana zone—probably during niortensis 

times. A similar erosion occurred at a slightly earlier date (blagdeni hemera) 

on the other side of the Channel, in Normandy, where it is marked by a 

conglomerate at the base of the famous Ironshot Oolite of Bayeux. These 

earth-movements seem to have heralded the great Bajocian Denudation, which 

preceded the transgression of Upper Inferior Oolite (garantiana) times. 2 

1 Based on S. S. Buckman, 1910, Q.J.G.S., vol. lxvi, pp. 52-89; L. Richardson, 1928-30, 

Proc. Cots. N.F.C., vol. xxiii, pp. 35-68, 149-86, 253-64 for the Burton Bradstock-Broadwindsor 

district; and idem, 1918, Q.J.G.S., vol. lxxiv, pp. 145-73 for the Crewkerne District. 

See also idem, Excursion, P.G.A., vol. xxvi, 1915, pp. 47-78. 

2 A curious white lithographic limestone observed by Buckman at Burton Bradstock in

INFERIOR OOLITE: DORSET COAST 191 

The layers of the Red Bed give evidence of most of the remaining zones of 

the Middle Inferior Oolite (fig. 33). The upper layer is a hard, crystalline 

limestone, grey in colour and made up largely of crinoid fragments. Its age 

is not precisely known, but Richardson considers it of late Witchellice or 

sauzei date. The middle layer is also a hard crystalline limestone, but it is 

very distinct on account of its containing numerous ironshot ooliths, and the 

general colour is brown or pinkish. Fragments of this layer enter largely into 

the composition of the niortensis conglomerate. The date is Witchellice or 

TOP OF THE 

8 RID PORT 

SANDS 

AST AM E B£D 

SNUFF BOXES" 

YELLOW CONGLOMERATE 

5CI55UM BED 

OPALINIFORME 

> AALENSIS 

FIG. 33. Comparative sections of the Lower and Middle Inferior Oolite at Chideock Quarry 

Hill (left) and Burton Bradstock, Dorset. After L. Richardson, 1927, Proc. Cots. N.F.C., 

vol. xxiii, pp. 51, 60. 

perhaps early sauzei. The lower layer is also highly oolitic and ferruginous, 

but it is readily recognized by its large limonitic concretions, locally called 

'snuff-boxes'. The nucleus of the snuff-boxes is often a rolled and bored 

piece of a thick-shelled Myoconcha or Ctenostreon, fragments of which abound. 

The date of this lowest layer is probably late discites hemera. Its snuff-boxes 

may be identified in the conglomerate above. 

Beneath the Red Bed is another important stratigraphical gap, corresponding 

with the Aalenian Denudation, the effects of which are widespread in 

Southern England and the Continent. It is marked by the Yellow Conglomerate, 

a pebbly layer with an average thickness of only 3 in., but containing 

derived fossils of the scissum, murchisonce, bradfordensis and concava zones. Its 

latest fossils are of early discites date, from which it can be said that the 

association with a niortensis fauna, and believed by him to occur as remanie pebbles in a conglomerate 

of that age, has been explained by Richardson as a secondary deposit resulting from 

water percolating down fissures, and he has shown that it is present both near the top of the 

Red Bed and in the Bridport Sands. The white rock is beyond any doubt of secondary origin, 

due to infiltration. It is associated with the breccia of a large fault, which brings down Forest 

Marble against Bridport Sands (Upper Lias) and veins of it can be seen running down into 

the sands. I myself reached this conclusion independently, and it was subsequently confirmed 

on visiting the spot with Mr. Richardson. (See S. S. Buckman, 1910, Q.J.G.S., vol. lxvi, 

pp. 69-71; L. Richardson 1915, P.G.A., vol. xxvi, p. 56; S. S. Buckman, 1922, Q.J.G.S 

vol. lxxviii, pp. 420-31).


conglomerate was formed at that date, deriving its materials from the destruction 

of the whole of the Lower Inferior Oolite. Among the many fossils of the 

Yellow Conglomerate are broken specimens of Brasilia bradfordensis, Burtonia, 

Ludzoigella, Cirrus nodosus, and Astarte (Coelastarte) excavata. 

The only undisturbed remnant of the Lower Inferior Oolite (as here understood) 

is a portion of the scissum zone, consisting of 18 in. of grey sandrock 

with the zonal ammonite, but lithologically more like the underlying Bridport 

Sands. To the top of the Scissum Bed the Yellow Conglomerate is firmly 

cemented. 

Four to six miles north-east of Bridport, around Powerstock, North 

Poorton and Mapperton, the whole of the Middle and Lower Inferior Oolite 

above the Scissum Bed is represented by only 2 ft. of strata, and in one quarry 

at Powerstock it is reduced to 15 in. From this it may be inferred that still 

farther east, below the Chalk Downs, the formation thins out altogether, as it 

probably did out to sea, over the Weymouth Anticline. 

In the opposite direction, up the dip slope to the west and north-west, 

the beds expand. The eroded surface below the discites zone, marking the 

'Aalenian Denudation' (better, Bajocian Transgression), rises and older beds 

beneath begin to assume separate identity. The change takes place roughly 

west of a line drawn from Bridport northward to Beaminster. 

At Chideock Quarry Hill, west of Bridport, the blagdeni and niortensis zones 

are missing, but the remainder have expanded to 9 ft. At the base of the Red 

Bed, which consists of dark brown, sandy, ironshot oolite with numerous 

Witchellice and crinoid fragments, is a trace of the discites conglomerate with 

rolled ammonites of bradfordensis date, as at Burton Bradstock (the Yellow 

Conglomerate). Beneath, however, with an eroded upper surface, instead of 

the Scissum Bed is 2 ft. of yellow limestone crowded with Ludwigia murchisonce. 

This is locally called the Wild Bed, and its lower half has been separated by 

Buckman as a separate zone, the Ancolioceras zone, on account of its containing 

a mixture of Tmetoceras and Opalinoid ammonites. Beneath, the Scissum 

Bed has expanded to 3 ft. 

Similar relations obtain along the western edge of the outcrop for some 

6 miles northward from the coast, where a fine section is displayed at Stoke 

Knap or Waddon Hill, 2 miles west of Beaminster. Here } Witchellice, 

Shirbuirnice, discites, concava, bradfordensis and murchisonce deposits have been 

recognized, totalling 5 ft. in thickness. The top is planed off at the base of 

the Upper Inferior Oolite and the surface is overgrown with oysters. The 

scissum zone, though thick, is ill defined, having become a sandy grit continuous 

with the Brachiopod Beds of the underlying Bridport Sands. 

This section is more complete than most in the neighbourhood. In passing 

north into the Crewkerne District and east, down the dip-slope, a great hiatus 

becomes general, in which Middle Inferior Oolite disappears. Except 

possibly at Dinnington, whence labels in the Moore collection at Bath allege 

that ammonites of the concava and discites zones were obtained, there is no 

rock assignable to any zone above that of bradfordensis. 

The Inferior Oolite hereabouts caps a great thickness of Yeovil Sands, left 

as isolated patches and blocks between faults. At first the bradfordensis zone, 

removed by the discites erosion on the coast, appears in what is for Dorset 

considerable thickness—3 ft. 7 in. at Beaminster—and is full of ammonites.

INFERIOR OOLITE: SHERBORNE 193 

At Conegar Hill, Broad Windsor, however, close to Waddon Hill, it has been 

again removed completely, Upper Inferior Oolite coming to rest on the 

murchisonce zone. At Misterton Limeworks and South Perrott it reappears, 

an impersistent bluish-grey ironshot bed, 4 in. thick. Beneath is the murchisonce 

bed, a hard bluish-grey limestone from 1 to 3 ft. thick, and yielding 

Pseudoglossothyris simplex, Zeilleria anglica, Variamussium pumilum, and other 

fossils. The scissum zone remains merely the upward continuation of the 

underlying sands, of which it may include from 3 ft. to 6 ft. 

(b) The Sherborne District 1 

In view of the sporadic erosion and partial removal of the Lower and Middle 

Inferior Oolite in the Beaminster-Crewkerne district, it is not surprising that 

farther on, where the outcrop turns east towards Sherborne, they have been 

removed altogether by the Bajocian Denudation. For several miles Upper 

Inferior Oolite rests directly on Bridport Sands. 

The first reappearance, Mr. Richardson informs me, is at North Coker, 

about 2 miles south-west of Yeovil, where probably—for the sections are not 

very satisfactory—the sequence is similar to that in the better known section 

at Stoford, about a mile and three-quarters farther east (fig. 45, p. 233). Here 

the Fuller's Earth lies only about 3 ft. above the Yeovil Sands. The Lower, 

Middle and Upper Inferior Oolite then thicken steadily towards Sherborne. 

At Bradford Abbas, Sandford Lane and other places, the lower zones form 

the famous fossil beds which have yielded perhaps the richest store of wellwell-preserved 

mollusca of all kinds obtained from any part of the Jurassic 

System in England. 

It was the area embracing Sherborne, Milborne Port and Bradford Abbas 

that formed the subject of the late S. S. Buckman's earliest researches, carried 

on from his father's farm at Bradford Abbas. The publication in 1893 of his 

masterly paper, 'The Bajocian of the Sherborne District', made this classic 

ground. In the numerous quarries the detailed zonal succession of the 

Inferior Oolite was first worked out, the crowded ammonites being carefully 

collected, inch by inch, from their proper beds. The unparalleled richness of 

the ammonite fauna is best illustrated by the profusion of genera and species 

figured by Buckman in his later years in Type Ammonites, from the worldfamous 

quarries of Bradford Abbas, Sandford Lane, Oborne, Compton and 

the neighbourhood. 2 Here too, Buckman and his father collected many of the 

finest of the gastropods, in a superb state of preservation, that were figured in 

Hudleston's Monograph of the Inferior Oolite Gastropoda. 

As the result of his refinements in stratigraphy, Buckman was able to show 

that at the beginning of the murchisonce hemera there was an overstep westward, 

followed by a gradual recession eastward throughout the rest of Lower 

and Middle Inferior Oolite times. This may be taken to be the regression 

which culminated in the Bajocian Denudation, and was followed in Upper 

Inferior Oolite times by renewed westerly transgression. 

Those who wish to acquaint themselves with the district cannot dispense 

1 Based on S. S. Buckman, 1893, 'The Bajocian of the Sherborne District', Q.J.G.S., 

vol. lxix, pp. 479-522; and L. Richardson, 1932, Proc. Cots. N.F.C., vol. xxiv, pp. 35-85. 

2 Space forbids giving lists of Inferior Oolite ammonites, very large numbers of which have 

been figured by Buckman also in his monograph.

194 LOWER OOLITES 

with the detailed descriptions supplied by Buckman's paper and Richardson's 

invaluable revisionary work; the present object is only to show the general 

development of the strata. In compiling the following summary I have drawn 

largely upon a correlation-table very kindly lent me for the purpose by 

Mr. Richardson in advance of publication. 

SUMMARY OF THE LOWER AND MIDDLE INFERIOR OOLITE OF THE 

SHERBORNE DISTRICT 

Blagdeni Zone. Absent in the western part of the district. Appears at 

Halfway House as a thin seam 0-2 in. thick; 0-6 in. at Louse Hill; absent 

again at Sandford Lane; thickening in the east to a hard grey-brown or pinkish, 

irony stone (6 in.-2 ft. 3 in.) at Clatcombe and Oborne. At Milborne Wick 

the zone consists of 10 in. of white crumbly rock with green grains of glauconite, 

and is crowded with fossils, of which the commonest is Astarte spissa 

S. Buckman. 

Sauzei Zone. Traces at Halfway House and locally to the west; 6-12 in. 

at Stoford; top part of the Fossil Bed at Sandford Lane; 4 in. at Oborne; 

white and grey limestone 1 ft. 8 in. at Milborne Wick. 

Witchelliae and Shirbuirniae Zones. Absent in the west and at Halfway 

House; first appears as the lower part of the Fossil Bed at Sandford 

Lane (the total thickness of which is 1 ft. 9 in.); thickening eastward to 3 ft. of 

hard blue limestone at Oborne and 13 ft. of grey sandy limestone at Milborne 

Wick. 

Discites and Concava Zones. Fossil bed in the west, thickening eastward 

from 10 in. at Clayton's Quarry to 3 ft. 8 in. at Halfway House. Locally 

Richardson has been able to separate the two zones, but at Oborne and 

Halfway House the bed is less fossiliferous and separation is more difficult. 

Buckman stated that the 3 ft. of blue-centred, yellow, ironshot limestone 

forming most of this bed at Halfway House yielded Ludwigella concava 

abundantly. Farther east the zones thicken still more. At Sandford Lane 

they are readily separable—the discites zone consists of 1 ft. 3 in. of sandy 

limestone and sand immediately below the Fossil Bed, and the concava zone 

of 3 ft. of sandy stone with L. concava and other fossils, as at Halfway House. 

Still farther east and north, at Oborne and Corton Downs, the concava, 

discites and probably Shirbuirnice and Witchellice zones become blended in a 

uniform development of grey, sandy, glauconitic limestone with sandy and 

marly partings. Here, owing to the rarity of ammonites and other fossils, the 

different zones cannot be separated. 

Bradfordensis Zone. Absent or locally represented only by the thinnest 

traces west of Halfway House, but there consisting of 1 ft. 2 in. of yellow 

ironshot limestone, and thickening eastward. Best seen at Marston Road 

Quarry, where it is separable into two layers: an upper, the Rhynchonella 

ringens Beds (1 ft. 8 in.) and a lower the 4 Perisphinctes y brebissoni Beds (1 ft.). 

The upper layer overlaps the lower westward to Halfway House. 

Murchisonae Zone. Yellow and blue limestone, 10 in.-2 ft., in the west, 

the upper portion locally called the Paving Bed. Probably represented in 

thicker development to the east, together with the bradfordensis zone, but the 

exposures are too shallow to reach them. Apparently absent at Stowell, near 

Milborne Port.

INFERIOR OOLITE: COLE SYNCLINE 195 

Ancolioceras and Scissum Zones. Generally absent, but recognized by 

Richardson in a 1 ft. 6 in. band at Marston Road Quarry. 

In a boring made in 1907-8 at Stowell, north of Milborne Port, within the 

Fuller's Earth outcrop, the total thickness of Lower and Middle Inferior 

Oolite seems to have been about 40 ft. The Rhynchonella ringens Beds (bradfordensis 

zone) were proved, within 2 ft. of the base of the limestones, and 

ammonites of the sauzei zone 32 ft. higher up. 1 

Immediately west of this boring, higher up the dip-slope, the Lower and 

Middle Inferior Oolite disappear, having been removed by the Bajocian 

Denudation. The beds are last seen at Corton Downs, 4 miles north of 

Sherborne, beyond which Upper Inferior Oolite oversteps on to Yeovilian 

sands for the next 6 miles over the North Devon Axis. 

(c) The Cole Syncline 2 

Centred at Cole, midway between Bruton and Castle Cary, and between 

the North Devon and Mendip Axes, is a small syncline, in which Lower and 

Middle Inferior Oolite is preserved to a thickness of about 10 ft. This outlying 

patch was first described in detail by Richardson, of whose account the 

following is a summary. The usual non-sequence was detected at the base of 

the discites zone, the bradfordensis and concava zones having been removed 

before the Bajocian Transgression. 

SUMMARY OF THE LOWER AND MIDDLE INFERIOR OOLITE OF THE COLE SYNCLINE 

Blagdeni Zone. Hard ironshot oolite, 1 ft., with Teloceras blagdeni, the 

top levelled, with oysters attached. Seen only in Lusty Quarry, Bruton. 

Sauzei Zone. Pecten-bed. Grey limestone with Entolium, 1-3 ft., seen in 

Lusty and Sunny Hill Quarries, 3 Bruton. 

Witchelliae and Shirbuirniae Zones. Grey limestone, a downward continuation 

of the Pecten-bed, and sometimes combined with it, 1-2 ft. 

Discites Zones. Ammonite bed, 2 ft. at Lusty Hill; 3 ft. 3 in. at Pitcombe 

Rock, I mile south of Sunny Hill Quarry; full of ammonites which are difficult 

to extract:—Graphoceras inclusum S. Buck., Terebratula eudesii Oppel. 

(Non-sequence: concava and bradfordensis zones absent.) 

Murchisonae Zone. Hard grey limestone, 1-3J ft., passing into a conglomeratic 

bed at Lusty Hill, 1 ft. 10 in., and containing Montlivaltia cf. lens 

Ed. and H., the first sign of corals in the Inferior Oolite. 

(Non-sequence: Ancolioceras and scissum zones absent.) 

II. THE MENDIP AXIS AND DUNDRY HILL 

For many miles north of the Cole Syncline there is no trace of Lower or 

Middle Inferior Oolite. Over the eastern end of the Mendip Axis the Upper 

Inferior Oolite transgresses over progressively lower beds until it comes to 

rest on the Carboniferous Limestone, as described in the next chapter. 

Nevertheless, on the north side of the Mendips, 22 miles from Cole, there 

is preserved on the western part of Dundry Hill an outlier of Lower and 

Middle Inferior Oolite of the Dorset-Somerset type (fig. 34). Consisting 

1 J. Pringle, 1909-10, Sum. Prog. Geol. Surv. for 1908, pp. 83-6, and for 1909, pp. 68-70. 

2 L. Richardson, 1916, Q.J.G.Svol. lxxi, pp. 494-503. 

3 Unfortunately the fine exposure at Sunny Hill is fast becoming obscured, houses and 

gardens having been built in the old quarry.

WEST 

.END 

EAST 

DUNORY 

E A5T 

MAES 

KNOLL 

FIG. 34. Diagrammatic longitudinal section through Dundry Hill, Somerset. (After Buckman and Wilson, 1896, Q.J.G.S., vol. Iii, p. 695.) 

(Re-drawn and the terminology brought up-to-date.)

MENDIP BATH OLD SODBURY WOTTON STROUD PAINSWICK BIRDLIP CLEEVE BOURTON ICCOMBVALEOF 

HILLS UNDER EDGE HILL ON THE WATER MORETON 

FIG. 35. Horizontal diagrammatic section through the Inferior Oolite Series of the Cotswold Basin, based on the works of S. S. Buckman and L. Richardson. The top of the old parkinsoni zone (sensu lato) is used as horizontal datum, the section thus representing approximately 

the condition of the region at the end of schlcenbachi hemera, or at the beginning of the deposition of the zigzag beds. Modern erosions eliminated. Horizontal scale 1 in. = 6 miles. Vertical scale 1 in. = 100 ft.

INFERIOR OOLITE: COTSWOLDS 197 

principally of ironshot oolites, it stands in the sharpest possible contrast with 

the Cotswold type of deposit, and furnishes convincing evidence that, as in 

Upper Lias times, the shallow belt separating the Cotswold basin of deposition 

from the Somerset-Dorset basin lay some distance north of the Mendips. 

The thickness of the Dundry Beds has never been accurately determined, 

but it is not very great. At the base are a few feet of hard, massive, irony 

oolites, representing the murchisonce and bradfordensis zones, overlain by grey 

limestone and marls representing the concava and discites zones. Above this 

comes the fossiliferous White Ironshot, chiefly of Shirbuirnice date, but including 

a Witchellia bed, capped by the Ironshot Oolite proper, forming the 

sauzei zone. From both of these ironshot limestones large collections of wellpreserved 

mollusca have been made and some may be seen in most of the 

museums in England. 

The blagdeni zone has been everywhere removed from the hill by the Bajocian 

Denudation. At the eastern end the denudation has also destroyed the whole 

of the underlying zones, bringing Upper Inferior Oolite down on to Yeovilian 

sands as on the main outcrop. 1 

III. THE COTSWOLD HILLS 2 

North of Bath, along the Cotswold escarpment, many new types of deposit 

representing the Lower and Middle Inferior Oolite make their appearance 

above the Cephalopod Bed, first becoming visible at Horton, 4 miles north of 

Old Sodbury, and thickening northward. The first to appear is about 6 ft. 

of sandy, ferruginous limestone yielding Tmetoceras scissum—the equivalent 

of the Scissum Bed of Dorset. It thickens to 9 ft. about Stroud and 

forms a basement-bed to the Inferior Oolite all through the Cotswolds, in 

places reaching a thickness of over 30 ft. 

Above the Scissum Beds in the district between Sodbury and Dursley a 

series of oolitic limestones gradually appears, consisting of layers of freestone 

alternating with layers of detritus of Crinoidea, Echinoidea, and bivalves, 

with small oysters attached to some of the beds. These limestones, which 

reach 25 ft. in thickness, w T ere named by Witchell the LOWER LIMESTONES. 

Owing to the absence of diagnostic fossils, little progress has been made since 

Witchell's days in the determination of their exact date. They were usually 

regarded as forming the base of the murchisonce zone, but Buckman suggested 

that they may represent the Ancolioceras zone. 

More oolites succeed the Lower Limestones, reaching a thickness of 45 ft. 

about Dursley and continuing to thicken northward. These are known as the 

LOWER FREESTONE. They first come to be separated from the Lower Limestones 

at Uley Bury, near Durlsey, by a seam of large pisoliths, which thickens 

later into a richly fossiliferous accumulation known as the PEA GRIT. The 

two together represent the murchisonce zone. The bradfordensis zone follows 

with a mass of incoherent oolite called the OOLITE MARL, the upper portion of 

which is consolidated to form an UPPER FREESTONE. 

1 S. S. Buckman and E. Wilson, 1896, Q.J.G.Svol. Iii, pp. 669-720; and 1901, P.G.A., 

vol. xvii, pp. 152-8. 

2 For the South Cotswolds:—L. Richardson, 1910, Proc. Cots. N.F.C., vol. xvii, pp. 63-136, 

and 1908, P. G.A.y vol. xx, pp. 514-29; for the Mid-Cotswolds:—S. S. Buckman, 1895, Q.J. G.S., 

vol. li, pp. 388-462, and L. Richardson, 1904, Handbook to Geol. Cheltenham; for North Cotswolds:—S. 

S. Buckman, 1897, Q.J.G.S., vol. liii, pp. 607-29, and idem, i90i,vol. lvii,pp. 126- 

55, and L. Richardson, 1929, 'Geol. Moreton in Marsh', Mem. Geol. Surv.


The top of the Upper Freestone is often bored and overlain by a pebbly and 

conglomeratic bed, and the concava zone is missing. The discordant Bajocian 

beds then succeed, consisting of variable, fossiliferous, rubbly limestones and 

marls known as the RAGSTONES, which represent the discites, Shirbuirnice 

and Witchellice zones. 

The Aalenian Denudation preceding the Bajocian Transgression, already 

familiar in Dorset and Somerset, caused the removal of the concava deposits in 

the Western Cotswolds. Its effects hereabouts are the same as farther south, 

in spite of the great difference in the facies of the rocks, but farther north and 

east, in the Central and North Cotswolds, they are not perceptible, and 

deposits of concava date are present. 

The whole of the strata in the Cotswold Hills, from the Middle Lias to the 

Ragstones, w r ere laid down in a gradually sinking syncline between the anticlinal 

axes of the Malverns and the Bath-Mendip district on the one hand and 

the Vale of Moreton on the other. Over these axes deposition was probably 

almost at a standstill, but in between sediments accumulated to a thickness of 

about 800 ft. After the formation of the Ragstones, however, not only were 

uplift and denudation renewed along the main axes, but there was also accentuated 

activity along the Birdlip Anticline (referred to on p. 75), which 

strikes roughly NW.-SE. through Birdlip Hill and runs along the line of the 

Roman Ermine Street towards Cirencester. The effect of this axis was now to 

divide the Cotswold region into two minor synclines, in which the Ragstones 

were preserved, while they were completely removed in the centre. At the 

outcrop about Birdlip, upon the crest of the anticline, Upper Inferior Oolite was 

deposited directly upon Upper Freestone (bradfordensis zone) (figs. 35 and 36). 

The centre of the southern syncline was located near Painswick, but comparatively 

little has been left of it owing to recession of the Cotswold escarpment. 

The northern syncline is better preserved and in it the succession of rocks is 

more complete. The axis of depression runs through the plateau promontory 

of Cleeve Hill, the highest point in the Cotswolds (1,070 ft. O.D.), towards 

Chedworth, and is then lost down the dip-slope below the Great Oolite. On 

the Cleeve Hill plateau the highest beds of the Ragstones are preserved, 

belonging to the sauzei zone, not found at any other locality in the Cotswolds. 

Still higher beds may have existed over the Vale of Gloucester before the 

retreat of the escarpment, but if so they have entirely disappeared. 

The strata that accumulated within the synclinal of the Cotswolds in 

Lower and Middle Inferior Oolite times reached a thickness of about 300 ft., 

without making allowance for the blagdeni or niortensis zones, which may have 

been deposited and subsequently removed by the Bajocian Denudation. They 

consist of oolites, pisolites, broken-shell limestones, masses of conglomerated 

Echinoderm remains, shells, sponges, and coral fragments. They are essentially 

neritic accumulations, and along the coast to which they bear witness coral 

reefs and shell banks were forming apparently in a semi-tropical climate. 

The coast was certainly that of the old Welsh landmass, but exactly where 

it lay will probably never be known. The Cotswold Hills are largely built of 

the debris torn from coral reefs by breakers. Inter stratified with the debris 

are some layers of coral which actually grew upon it, probably from 5 to 25 

miles from the shore. The main fringing reefs and the white strand of oolite


sand that lay behind them, perhaps along the Malvern and Abberley Hills, 

perhaps farther west, have been entirely swept away. 

The Cotswold deposits, by reason of their origin, are essentially different 

from the strata of equivalent age in Dorset and Somerset. There all the zones 

are represented by thin condensed deposits, crowded with well-preserved 

ammonites, gastropods and lamellibranchs, indicating that deposition of 

FIG. 36. Map showing the different beds in the Cotswolds upon which the Upper Infer or 

Oolite was deposited after the Vesulian Transgression. (After S. S. Buckman, Q.J.G.S., 

1901, vol. lvii, pi. vi, p. 154, and embodying corrections by L. Richardson in Q.J.G.S 

1903, vol. lix, p. 382.) 

sediment was always slow, sometimes virtually at a standstill. In the Cotswolds, 

on the contrary, sedimentation was rapid and ammonites are rare and 

confined to certain horizons, where they usually seem to have drifted in from 

a distance. Correlation by means of ammonites is of so little value, owing to 

their rarity, that recourse must be had to other forms of life. The brachiopods, 

with their colonial and sessile habit of growth, seem to have found the banks 

of debris a congenial habitat, and their numerous well-preserved shells have 

been largely used in stratigraphical work. 

It is only possible to account for the differences between the Dorset- 

Somerset and the Cotswold strata by supposing that they were laid down in 

two basins of deposition more or less (but not entirely) separated by a landbarrier 

or shallows. In considering where such a barrier might have been


situated it is necessary to remember that the Bajocian strata of the Dundry 

outlier, on the north side of the Mendip Hills, are essentially a continuation of 

the Dorset-Somerset type of deposit. The principal barrier therefore cannot 

have been the main Mendip Axis. It seems, rather, to have lain somewhere in 

the neighbourhood of Bath and Keynsham, where we saw that minor folding 

was operative during the formation of the Lower Lias. S. S. Buckman 

visualized the Dundry area as connected with the southern sea by way of a 

circuitous channel passing round the western end of the Mendips and over 

Sedgmoor (see fig. 15). 1 The evidence of the Westbury boring, however, 

would seem to suggest a connexion round the eastern end of the Mendips. 

There, beneath the Corallian outcrop, the Inferior Oolite had the great 

thickness of about 128 ft., and near the base, at about 1,122 ft. below the 

surface, was found a thin band of dark grey limestone containing fragmentary 

ammonites, which Buckman suggested seemed to belong to the murchisonce 

zone. 2 This seems to indicate that eastward, down the dip-slope beneath the 

younger formations, are preserved the relics of the marine connexion of Lower 

Inferior Oolite times between the Dorset-Somerset area and the Cotswold 

Basin, and it may have been a tongue of this deeper sea that projected westward 

to Dundry Hill. A similar connexion is demanded also during the 

Upper Lias period, to account for the resemblance between the Upper Lias 

of Dundry Hill and that of the outliers of Brent Knoll and Glastonbury Tor, 

at all of which places the Dumortierice subzone is represented by a thick clay 

as in Dorset, while in the Cotswolds it forms part of the Cephalopod Bed. 

The elucidation of the sequence, structure and palaeontology of the Inferior 

Oolite of the Cotswolds was primarily the work of S. S. Buckman, and to it he 

brought the knowledge and experience gained in his first geological studies 

of the same formation in the Sherborne district. Methods were invented to 

meet contingencies as the work progressed, and much was added to the 

science of palaeontology as a result, particularly in the province of brachiopod 

morphology and phylogeny. The stratigraphical conclusions were read to 

the Geological Society in three long papers, published in 1895, 1897, and 1901. 

These laid the foundations of the minute study of the Inferior Oolite, which 

has been amplified and extended to the Dorset coast on the one hand and into 

Northamptonshire on the other by Mr. L. Richardson in the last thirty years. 

The high value of the results, both theoretical and practical, can hardly be 

over-estimated, and we now know more of the Inferior Oolite than of any other 

part of the Jurassic System. 

SUMMARY OF THE MIDDLE AND LOWER INFERIOR OOLITE OF THE COTSWOLDS 3 

(Niortensis and blagdeni zones absent.) 

THE RAGSTONES (max. thickness 80 ft.) 

Sauzei Zone (PHILLIPSIANA and BOURGUETIA BEDS), max. 24 ft.: These beds 

are confined to the Cleeve Hill plateau. They consist of some dozen or more 

beds of hard limestone, some of them shelly, yielding Heimia phillipsiana 

(Walk.), Rhynchonella quadriplicata Dav. non Zeit. and other brachiopods, 

1 S. S. Buckman, 1890, 'The Relations of Dundry with the Dorset-Somerset and Cotswolds 

areas during part of the Jurassic Period', Proc. Cots. N.F.C., vol. ix, pp. 374-87; and 1923, 

T.A.y vol. iv, map, p. 52. 

2 J. Pringle, 1922, Sum. Prog. Geol. Surv. for 1921, p. 151 

3 Based on the works of Buckman and Richardson; see Bibliography.

PLATE VIII 


Leckhampton Hill, near Cheltenham. 

Showing the inland scarp of the Lower Inferior Oolite (Lower Freestone) 

bared by ancient quarrying. In the upper view is the Devil's Chimney. The 

Liassic plain with the town of Cheltenham is seen below.

PLATE IX 


Leckhampton Hill Quarry, Cheltenham. 

Showing a section of the Inferior Oolite from the Upper Lias to the Ragstones. 

In the foreground are ruins of lime-kilns. O. M. = Oolite Marl, 

UP. FR. = Upper Freestone. 


Crickley Hill, near Cheltenham. 

Showing quarried cliff of Pea Grit Series, as viewed from the Birdlip road 

above Tuffley's Quarry, west of the 'Air Balloon'.


together with large molluscs such as Bourguetia striata (Sow.), Ostrea (Lopha) 

'marshiV (auctt.), Ctenostreon pectiniforme (Schloth). Among the ammonites 

occasionally found is Emileia vagabunda. 1 

Witchelliae Zone (WITCHELLIA GRIT 2 and NOTGROVE FREESTONE), max. 

25-30 ft. The WITCHELLIA GRIT consists of 3-4 ft. of grey or brown ironshot 

limestone, some layers flaggy and shelly, yielding ammonites of the genus 

Witchellia, with Tubithyris zurighti(T)av.), an Acanthothyris and lamellibranchs. 

The outcrop forms a ring round the Cleeve Hill plateau. 

The NOTGROVE FREESTONE, 15-25 ft. thick, has a wide surface outcrop over 

the greater part of the main hill-mass of the North and Central Cotswolds, 

and it is also the highest stratum remaining in the Painswick Syncline. It 

consists typically of hard fine-textured, white, oolitic limestone, usually 

unfossiliferous, but locally abounding in the little Pectinid, Variamussium 

pumilum (Lamk.). Ammonites resembling Sonninice sometimes occur at the 

base. The freestone 3 takes its name from railway-cuttings at Notgrove, 

between Bourton on the Water and Cheltenham, where its stratigraphical 

position was first discovered by Buckman. 

Shirbuirniae Zone (GRYPHITE GRIT), max. about 8 ft. This so-called 'grit' 

is a massively bedded, somewhat sandy limestone, characterized by an 

abundance of oysters of the genus Gryphcea, with Entolium sp. and Pachyteuthisgingensis 

(Oppel). Other fossils are rare. On the Cleeve Hill plateau the 

thickness is 5 ft., and in the main hill-mass up to 8 ft. 

Discites Zone (BUCKMANI and LOWER TRIGONIA GRITS): The BUCKMANI 

GRIT (max. 17 ft.) is a yellowish, sandy limestone, generally merging gradually 

up into the Gryphite Grit, but distinguishable by the greater abundance of 

fossils. In the Mid-Cotswolds it always contains a readily-distinguished sandy 

layer, which yields the characteristic Terebratulid, Lobothyris buckmani. 

. The LOWER TRIGONIA GRIT (max. 7 ft.) is a highly fossiliferous deposit, 

consisting of rubbly, often ironshot, limestone and marl. The characteristic 

Trigonice are T. costata Sow. and T. formosa Lyc., with which occur Pholadomya 

fidiculay Opis cordiformis and various other lamellibranchs and 

brachiopods. 

Corals, principally Chorisastrcea gregaria (M'Coy), abound where the beds 

are well developed. In many places the basal portions are conglomeratic, 

containing iron-coated and bored pebbles of limestone and calcareous clay or 

mudstone, the latter perhaps derived from erosion of the Snowshill Clay. 

UNCONFORMITY—BAJOCIAN TRANSGRESSION 

Concava Zone (TILESTONE, 18 ft.; SNOWSHILL CLAY, 15 ft.; and HARFORD 

SANDS, 9 ft.). These beds are confined to the eastern limb of the Cleeve Hill 

Syncline, and best developed between Winchcomb and Chipping Campden 

on the western side of the main promontory of the North Cotswolds. 

The TILESTONE (best exposed in the Holt Quarry, near Blockley) consists 

of sandy oolitic limestone with a variable proportion of sand, which predominates 

towards the north and gives rise to a sandy soil. The upper portion 

locally contains well-rolled pebbles of oolite, denoting a minor penecontemporaneous 

erosion. Fossils are usually rare, but lamellibranchs sometimes 

1 Figured Buckman, T.A., pi. dccxxiii. 

2 The term 'grit* is a misnomer for this and the other so-called 'grits' of the Ragstones. 

3 Also a misnomer a6 it is nowhere soft enough for cutting with a saw. 

S:>4371 P

S A U Z E I 

WITCHELLIA 

SHIRBUI RN 

DISCITES 

BRADFORDENSIS 

MURCHISONAL 

? ANCOLIOCERAS 

SCISSUM 

PH I LLL PSIANA 

BEDS 

b0urguetia 

BEDS 

I OFT. 

14 FT. 

WITCHELLIA „ 

QRIT 4 F T. 

notgrove 

FREESTONE 

gryphite 

grit 

buckmani 

grit 

2 5 FT. 

5-8FT 

17 FT. 

lower 

7 ft. 

trigonia grit 

upper 

freestone 

i 5 ft. 

20 FT. 

oolite marl 

[FIMBRIA s 10 ft 

STAGE) 

lower 

45-130 FT. 

freestone 

SCISSUM ^ A RR 

BEDS 

( Cy/V O CEPH A L A 

STAGE) 

FIG. 37. Column showing the subdivisions recognized in the Lower and 

Middle Inferior Oolite in the Cotswold Hills. 

K 

03 

o 

< 

cL


occur, and a fish tooth and gastropod have been recorded. 'Tilestone* is 

another misnomer, due to an erroneous early correlation by Buckman with 

fissile roofing-slates since shown by Richardson to be Chipping Norton 

Limestone. 

The SNOWSHILL CLAY (max. 15 ft.) is a stiff green, brown, chocolate or 

black clay, thickest about Blockley and feathering out on Charlton Common, 

near Cheltenham, and also to the E. and S. 1 

The HARFORD SANDS (max. 9 ft.) are of even more local distribution than 

the Snowshill Clay, thinning out westward before they reach Charlton Common. 

They are a white and pale brown quartz sand, often cemented by 

calcium carbonate to form large doggers or sand-burrs. Analyses have been 

made by both Boswell and Skerl, who state that the composition is markedly 

different from that of the Cotswold Sands (Upper Lias); the Harford Sands are 

characterized by abundant sphene and rare kyanite. 2 

Bradfordensis Zone (UPPER FREESTONE, max. about 25 ft.; and OOLITE 

MARL, 10 ft.). 

The UPPER FREESTONE is only the indurated and usually more oolitic upper 

part of the Oolite Marl, and it varies in thickness accordingly. It is best 

developed in the Mid-Cotswolds and is the highest bed left in the centre of the 

Birdlip Anticline. To the east, where the Oolite Marl is well developed (e.g. 

at Notgrove), the Upper Freestone is thin and ill-differentiated from the marl. 

The same difficulty in separating them recurs in the extreme west, about 

Stroud. 

The OOLITE MARL is, after the Pea Grit, the most fossiliferous deposit in 

the Cotswolds. It consists of a soft mass of ooliths in a marl matrix, and is the 

home of abundant beautifully-preserved brachiopods, the most characteristic 

of which is Plectothyris fimbria, a species confined entirely to the Cotswold 

Hills. Species of 4 Zeilleria\ Pseudoglossothyris and Rhynchonella also abound, 

together with lamellibranchs, gastropods and a wealth of microscopic organisms—fragments 

of Crinoids, Ostracods and seven species of sponges. Locally 

corals are abundant. The Upper Freestone is usually less fossiliferous. Its 

characteristic brachiopod is Rhynchonella tatei, but since the acme of Plectothyris 

fimbria occurs immediately below, the whole was named by Lycett the 

'Fimbria Stage'. The designation has become obsolete because it was originally 

used to include also the Lower Freestone, which is best regarded as part of 

the murchisonce zone. 

Murchisonae Zone (LOWER FREESTONE, 45-130 ft.; PEA GRIT SERIES, max. 

30 ft.; and LOWER LIMESTONES of the West Cotswolds, 25-35 ft.). 

The LOWER FREESTONE is the thickest deposit of the whole Inferior Oolite 

and builds the main cliff-like escarpment all along the part of the Cotswolds 

facing towards Gloucester and Cheltenham. Its maximum thickness of about 

130 ft. is attained in the scarp of Leckhampton Hill, above Cheltenham, where 

it is laid bare in immense quarries, together with the other strata from the 

Upper Lias to the Lower Ragstones. It consists of a fine white oolite, much 

sought after as a building stone on account of its even texture, freedom from 

1 Richardson formerly thought that at Blockley its position was below the Harford Sand, 

but what he then took for Harford Sand has proved to be Tilestone, and so his Blockley Clay 

is the same as the Snowshill Clay of Buckman (see L. Richardson, 1929, 'Geol. Morton in 

Marsh', Mem. Geol. Surv., p. 39). 

2 J. G. A. Skerl, 1926, Proc. Cots. N.F.C., vol. xxii, pp. 153-60.


fossils and ease of working. It is not entirely devoid of fossils, however, many 

bands being largely made up of finely-comminuted shells, echinoderms and 

corals, while the very ooliths often contain at the centre the microscopic 

calcareous alga Girvanellapisolitica, first detected by E. B. Wethered. Macroscopic 

organisms, however, are almost entirely confined to two shelly layers, 

one of which is exposed 18 ft. below the Oolite Marl near the Devil's Chimney, 

where the Freestone is thickest, and displays a mass of shells and corals, a foot 

and a half thick. None of the fossils is really characteristic (Plate VIII). 

The PEA GRIT SERIES (including the LOWER LIMESTONES of the W.). In 

the west, about Stroud and Painswick, the strata between the Lower Freestone 

and the Scissum Beds can be clearly differentiated into a coarse pisolitic deposit 

above, known as the Pea Grit, and white crystalline limestones below— 

Witchell's Lower Limestones, already mentioned. Farther east, however, on 

Cleeve Hill, beds of pisolite occur low down in the Lower Limestones, while 

the higher beds, on the level of the Pea Grit of the western district, become 

non-pisolitic, massive and sandy. Still farther east, in the main hill-mass of 

the North Cotswolds, pisolitic structure disappears altogether, and the rock 

is a beautiful yellow freestone (Guiting Stone). On account of this it is best 

to consider the whole of the beds in the eastern half of the Cotswolds between 

the Lower Freestone and the Scissum Beds as the Pea Grit Series. 

The true Pea Grit, where typically developed, is a remarkable deposit of 

pisoliths the size of a pea, but somewhat flattened, containing tubules of 

Girvanella pisolitica and sometimes encrusted with Bryozoa. The best exposures 

are along the escarpment of Crickley Hill and in the Leckhampton 

Hill Quarry, where thousands of beautifully-preserved shells, brachiopods, 

echinoids and fragments of coral have been obtained (PI. IX). The principal 

brachiopod is the largest Jurassic species in Britain, Pseudoglossothyris simplex 

(J. Buckman), and Curtirhynchia oolitica is also characteristic. The seaurchin 

tests include Pygaster umbrella (semisulcata auctt.), Galeropygus 

agariciformis, Stomechinus germinans, Diplopodia depress a, Hemipedina (half 

a dozen species) and Cidaris spp. (sensu lato), besides the usual spines of the 

Regularia. 

The sea-urchins are essentially reef-dwelling animals, and the Pea Grit, 

besides being a repository of their hard parts, provides also the brst insight we 

can obtain into the nature of the corals of which the reefs were composed. As 

usual in the Jurassic, the chief reef-builders w T ere Isastrcea and Thamnastrcea 

(/. tenuistriata, T. terquemi, T. mettensis, &c.) supplemented by several species 

of Latimceandra and Montlivaltia. Ten species of sponges have also been 

obtained from the Pea Grit, and some are numerous. 1 

In the Lower Limestones, where pisolitic structure is not in evidence, the 

shells are nearly all comminuted, as in the Freestones above. But as usual 

there are a few shelly horizons, and one of these at Crickley Hill has yielded 

fine examples of Pseudoglossothyris simplex, Terebratula withingtonensis, 

Rhynchonelloidea subangulata and others. Here, too, was obtained the 

attenuated gastropod Ptygmatis (Bactroptyxis) xenos Hudleston, regarded as 

the earliest representative of the Nerineidce known in Britain. Eight species 

of sponges are known, some restricted to this horizon. 

A fossil of widespread distribution in the main hill-mass of the North 

1 L. Richardson and A. G. Thacker, 1920, P.G.A., vol. xxxi, pp. 185-6.

INFERIOR OOLITE: VALE OF MORETON 205 

Cotswolds is Variamussium pumilum (Lamk.), which marks the horizon of the 

upper part of the Lower Limestones. Buckman suggested that the Lower 

Limestones, in which no ammonites have been found, might be on the horizon 

of his Ancolioceras zone in Dorset. 

Scissum Zone. The Scissum Beds expand from 6 to 12 ft. in average thickness 

towards the Mid-Cotswolds, and in places they reach 30 ft. They consist 

usually of brown sandy limestones, but in the main hill-mass of the North 

Cotswolds the lower portions are largely represented by loose brown sand. 

The most characteristic and abundant fossils are Homoeorhynchia cynocephala 

(Richard.), R. subdecorata auctt., Aidacothyris blakei Walker, Astarte elegans 

Sow., Modiola sowerbyana d'Orb., and Pholadomya fidicula, but occasionally 

such ammonites as Tmetoceras scissum, Lioceras thompsoni Buck., and Hammatoceras 

are found. 


The broad tongue of Inferior Oolite forming the main North Cotswold 

hill-mass is bounded abruptly on the east by a N.-S. valley of Lower Lias. 

Beginning as the wide Vale of Moreton, this forks south of Stow on the Wold 

into the Evenlode Valley, which runs south-eastward, and the Vale of 

Bourton, which continues almost due south. In between the two forks of the 

valley a small triangular wedge of hills projects some eight miles northnorth-west 

of Burford, past the Rissingtons to Iccomb—the Iccomb hill-mass. 

On the east side of the Vale of Moreton the Cotswolds are continued, 

geologically speaking, by a broken plateau (on which Chipping Norton stands) 

bounded by the Moreton-Evenlode Vale on one side and the Cherwell Valley 

on the other. 

This plateau, though now so much dissected that it is little more than a 

group of outliers, still extends north-west of Banbury to the borders of Edge 

Hill, and its total length and breadth are roughly equal to those of the main 

North Cotswold hill-mass. Its greater dissection is due to the thinness of the 

Inferior Oolite beds, of which many of the components fail to cross the Vale 

of Moreton Axis, while others in crossing it become attenuated almost beyond 

recognition. 

The thinning out of the Inferior Oolite against the Vale of Moreton Axis 

was outlined by Buckman in his study of the North Cotswolds. More recently 

Richardson has devoted a number of years to the thorough investigation of 

both sides of the axis, the Iccomb hill-mass and the plateaux, and he has now 

made it possible to obtain a complete picture of the strata in the disturbed area. 

The attenuation of the various components of the formation as they pass 

eastward through the North Cotswolds is steady and continuous (fig. 35, p. 197). 

East of a line running NNW.-SSE. from Snowshill to between Bourton on the 

Water and Aston Blank there is no more Lower Trigonia Grit, while the rest 

of the discites zone, the much thicker Buckmani Grit, also disappears before 

reaching the edge of the hills at Bourton on the Hill, Stow on the Wold and 

Upper Slaughter. 1 

Along this edge there is also no Oolite Marl, and the remaining zones have 

become so thin that those who have not traced them continuously from the 

area of their fuller development find it difficult to recognize them. In Aston 

1 L. Richardson, 1929, 'Geol. Moreton in Marsh', Mem. Geol. Surv.> Ch. III.


Farm railway-cutting, on the edge of the hills west of Bourton on the Water, 

the whole of the Ragstones are reduced to 11 ft. of strata. Richardson has 

recognized a 7-in. band of Notgrove Freestone, with a bored upper surface, 

overlain directly by the transgressive Upper Inferior Oolite, and below it the 

following representatives of the underlying Ragstones—which together with 

the Notgrove Freestone represent a thickness of 100 ft. in the Cotswolds: 

Gryphite Grit 8 in.; Buckmani Grit 2 ft.; Lower Trigonia Grit, with pebbles, 

1 ft.; concava zone or Harford Sands and Tilestone 7 ft. (the Snowshill Clay 

missing). The surface of the Upper Freestone is bored, and although its 

full thickness is not seen, it cannot be very thick, for a few hundred yards 

farther east a quarry shows that it and the whole of the Middle Inferior 

Oolite have disappeared, leaving Upper Inferior Oolite (Clypeus Grit) resting 

on the lower part of the murchisonce zone (comprising thin representatives of 

the Pea Grit and Lower Limestones). 1 

Across the Vale of Bourton, on the Iccomb hill-mass, these last traces of 

Lower and Middle Inferior Oolite are no more seen, a nd Clypeus Grit rests 

directly on Upper Lias. 2 

The same conditions obtain eastward along both sides of the Evenlode 

Valley and in the southern part of the Chipping Norton plateau, south of a 

line running approximately north-east from Chipping Norton towards the 

Cherwell Valley, between Banbury and Adderbury, and so on towards Towcester. 

South of this line representatives of the Upper Inferior Oolite or later 

rocks, whatever they may be (Clypeus Grit at first, and later, towards the Cherwell 

Valley, Chipping Norton Limestone), overstep on to Upper Lias (see 

fig. 38). North of the line the Scissum Beds intervene and, in at least one or 

two places on the east of the Vale of Moreton, a representative of the 

Ancolioceras zone is also present. 

The locality where Richardson has detected the supposed Ancolioceras zone 

east of the Vale of Moreton is Cornwell, z\ miles west of Chipping Norton, 

and he believes it to be present also at Oatley Hill, between Hook Norton and 

Wichford. The highest beds seen, overlying the Scissum Beds, are sandy 

limestones full of Variamussium pumilum (the characteristic fossil of the Lower 

Limestones in the Cotswolds) and numerous other fossils. 

Over the rest of the area north of this SW.-NE. line, Scissum Beds crop 

out at the surface or are directly overlain by Upper Inferior Oolite or higher 

beds. They are in all lithological and palaeontological features a direct continuation 

of the Scissum Beds of the Cotswolds, consisting chiefly of brown 

sandy limestones, with Homoeorhynchia cynocephala, Pholadomya fidicula, 

Astarte elegans (at Compton Wyniates and Burton Dassett), the same ammonites, 

Lioceras thompsoni, Hammatoceras sp., and the same peculiar variety 

of the coral Montlivaltia lens. The usual thickness is about 7-10 ft. 3 

V. THE EASTERN MIDLANDS 

(a) Southern Northamptonshire: the Northampton Iron-field 

Eastward, towards Banbury, the sandy limestones of the Scissum Beds pass 

into calcareous sandstones and ferruginous sand. On the east side of the 


2 L. Richardson, 1907, Q.J.G.S., vol. lxiii, pp. 437-43. 

3 L. Richardson, 1922, Proc. Cots. N.F.C., vol. xxi, pp. 112-13, 118-20; and 1925, ibid., 

vol. xxii, p. 139.

INFERIOR OOLITE: NORTHAMPTONSHIRE 207 

Cherwell Valley they extend in a broad tract towards Towcester and 

Northampton, gradually thickening threefold and becoming more ferruginous 

in the lower part, until in the Northampton iron-field the base yields a rich 

ore. Throughout this tract, as far as Wellingborough and Kettering and up 

the valley of the Nene to beyond Oundle, there is no trace of any zone of the 

Lower or Middle Inferior Oolite higher than that of Ancolioceras. This and 

the Scissum Beds are overlain directly by sands of the age of the Chipping 

FIG. 38. Sketch-map showing the 'Scissum Line' and certain other boundaries. Outcrop 

of the Lower Oolites stippled, and the top of the Cornbrash represented by double line. 

Norton Limestone and in the east by the Upper Estuarine Series (Great 

Oolite). 

From the Oxfordshire border to the Humber these lowest representatives 

of the Inferior Oolite, grouped together as the NORTHAMPTON SANDS, are a 

constant and important feature. Besides being overstepped by various parts 

of the Great Oolite Series, they in turn rest non-sequentially upon Whitbian 

clays (the lower part of the Upper Lias) without the intervention of any 

Yeovilian. At the base they often contain pebbles and fossils derived from the 

Upper Lias, which in some places form a veritable bifrons bed. It was pointed 

out by Judd that the gas-chambers of these ammonites are filled with Lias, 

although they now lie in an ironstone matrix. 

The Northampton Sands are usually divided into the VARIABLE BEDS or 

LOWER ESTUARINE SERIES 1 above and the IRONSTONE SERIES below, the total 

1 Here restricted to exclude the White Sands of Southern Northamptonshire, which 

Richardson has shown to be of fusca date.


thickness reaching from 20 to 35 ft. and in some places much more (perhaps 

60-70 ft.). 1 

The VARIABLE BEDS fully justify their name. As a rule they consist principally 

of flaggy limestones, which pass by many gradations into calcareous 

sandstones and brown sands, while at some places, such as Brixworth and 

Harpole, they seem to become white sands and sandstone. In this last facies 

they are difficult to distinguish from the much younger White Sands of the 

fusca zone. At New Duston and elsewhere near Northampton, the rich, 

rusty, sandy limestone of the Variable Beds has been extensively quarried for 

building, while nearby, in Sandy Lane, west of Old Duston, the same beds 

pass into deep white sands. 

The building stones at New Duston and Northampton are highly fossiliferous 

in certain bands, particularly in a coarsely granular limestone, varying 

from crystalline to oolitic, called the Pendle. The fauna conclusively settles 

the early age of the beds, in spite of their similarity to some of the zigzag-fusca 

strata of the district. It includes Variamussium pumilum (Lamk.), Velata 

abjecta (Phil.), Lima rodburgensis Whidborne and other early forms, and very 

occasionally ammonites of Ancolioceras date. Buckman has figured from 

the Pendle of Bass's Pit, Northampton, a specimen of Ancolioceras mceandrus 

(Reinecke), 2 while Richardson has found at New Duston a less well preserved 

specimen indicating approximately the same date. 3 

At Harlestone, north-west of Northampton, a novel use has been found 

for a soft reddish-brown sandstone at the base of the Variable Beds, on the 

horizon of some of the building stone of New Duston: it is ground down, 

mixed with cement, and made into scouring bricks or 'cotters'. 4 

Mr. Beeby Thompson considers that some of the more calcareous parts of 

the Variable Beds, restricted to a small area around Northampton, indicate 

coral growth in the vicinity, and Richardson has pointed out their resemblance 

to some of the Lower Limestones of the Cotswolds, which, although they have 

yielded no ammonites, occupy the stratigraphical position of the Ancolioceras zone. 

The IRONSTONE SERIES is 27 ft. thick at New Duston near Northampton, but 

it does not usually exceed 12-20 ft., the average thickness worked being from 

8 to 12 ft. The main iron-field lies between Wellingborough, Northampton 

and Market Harborough, with a south-westerly extension to Towcester. 

There are also workings at intervals farther north, by way of Cottesmore, 

Market Overton and Leadenham to Lincoln. 

The ore is an oolitic green carbonate, resembling that in the Marlstone, but 

less calcareous than the Banbury ironstone and richer in iron, yielding from 

31 to 38 per cent. iron. On the whole it is more sandy, especially towards the 

base, where it passes down into green ferruginous sandstone. A peculiar 

result of weathering, which serves to distinguish the ore from that of the 

Marlstone, is the so-called 'box-structure'. This results from the vertical 

joint-planes and horizontal bedding-planes becoming filled with hard, dark 

brown, structureless limonite, dissolved out of higher layers by infiltrated water. 5 

1 B. Thompson, 1928, The Northampton Sand of Northamptonshire', and L. Richardson, 

1925, 'Certain Jurassic (Aalenian-Vesulian) Strata of the Duston Area, Northamptonshire* 

Proc. Cots. N.F.C.y vol. xxii, pp. 137-52. 

2 1928, T.A.y pi. DCCLXXXVI 1. 3 1925, Proc. Cots. N.F.C., vol. xxii, pp. 147-8. 

4 B. Thompson, 1925,Journ. Northants N.H.S. and F.C., vol. xxiii, p. 48. 

5 C. B. Wedd, 1920, Spec. Repts. Min. Resources, Mem. Geol. Surv., vol. xii, pp. 141-207.

INFERIOR OOLITE: NORTHAMPTON IRON-FIELD 209 

The heavy minerals, studied by Mr. Skerl, have yielded interesting information. 

An assemblage of minerals of thermal metamorphism (notably garnet, 

kyanite, sphene, chloritoid, spinel and staurolite) has been traced and they 

have been found to increase in size and quantity from all parts of the outcrop 

towards the Kettering district. From this fact, particularly when considered 

in relation to the known occurrences of the mineral chloritoid, Skerl deduces 

that the materials composing the Northampton Iron Ore were derived from 

the London landmass, to the south-east and east of the present outcrop, and 

directly from some metamorphic area undergoing denudation rather than 

from any previously-formed sediments. 1 

Palaeontologically the ironstone is at first disappointing, being often entirely 

barren. At certain localities, however, fossils are not uncommon, though 

generally preserved only as casts. The most significant are Nerinea cingenda 

Phil., which is found on the same horizon through Northants. and South 

Lincolnshire and in abundance in the Dogger of Yorkshire, Astarte elegans, 

Variamussium pumilum, Velata abject a, Ceratomya bajociana, Trigonia bella, 

T. compta, T. striata, T. sharpiana, and some brachiopods not yet worked 

out. 2 The ammonites are somewhat unsatisfactory and have given rise to 

considerable controversy, owing to the swamping of contemporaneous species 

by derived forms from the Upper Lias. Mr. Beeby Thompson has always 

maintained that they indicate an Upper Liassic age, but Richardson has 

brought forward incontestable proof that the latest species are identical with 

those in the Scisswn Beds of the Cotswolds. The forms on which he bases this 

conclusion are Lioceras thompsoni Buck, and several other species, and Hammatoceras 

spp. The occurrence of Tmetoceras scissum itself seems doubtful. One 

specimen is said to have been found near the top of the Ironstone Series. 3 

The significant SW.-NE. line, south of which the Scissum Beds thin out in 

Oxfordshire and disappear, is continued north-eastward along the southern 

boundary of the Northampton iron-field (fig. 38). In all the exposures 

around Brackley and beside the Cherwell Valley at Newbottle and Steeple 

Aston, and in the Fritwell railway-cuttings, beds younger than the Upper 

Inferior Oolite rest directly on Whitbian Lias, as in the Evenlode Valley 

(except for the absence of Clypeus Grit). Near Towcester the Scissum Beds 

are seen to be absent at the south end of the Blisworth canal tunnel, where 

only 5 ft. of sands (probably of fusca date) separate the Upper Lias from 

the Upper Estuarine Clay of the Great Oolite Series. Similarly farther northeast, 

about Horton, Bozeat and Wollaston, any sands that there may be 

separating these formations are so thin that they cannot be traced and the 

Great Oolite Series is mapped as resting directly on the Whitbian Lias. 

Comparable indications have been obtained in borings south-eastward, 

down the dip-slope, at Olney and Stony Stratford. In the deep boring at 

Calvert, south of Buckingham, on the outcrop of the Oxford Clay, some part 

of the Great Oolite Series was proved to have overstepped still farther, on to 

the algovianum subzone of the Lower Middle Lias. 4 

If we join all the places at which the last trace of Lower Inferior Oolite 

disappears, leaving Upper Lias and Upper Inferior Oolite or higher beds in 

1 J. G. A. Skerl, 1927, P.G.A., vol. xxxviii, pp. 375-94. 

2 L. Richardson, 1925, Proc. Cots. N.F.C., vol. xxii, p. 149. 

3 B. Thompson, 1928, Northampton Sandy p. 257. 

4 A. Morley Davies and J. Pringle, 1913, Q.J.G.S., vol. lxix, p. 311; and see below, p. 325.


contact, we obtain a nearly straight line over 50 miles in length. It can be 

plotted from near Upper Slaughter, on the west side of the Moreton Axis, 

passing rather north of Chipping Norton and somewhat south of Towcester 

(Stoke Bruerne) to Bozeat, near the junction of Buckinghamshire, Bedfordshire 

and Northamptonshire. 

That this line is continued much farther to the north-east, beneath the 

Chalk, was indicated by a deep boring in the Fens east of Southery, Norfolk, 

described by Dr. J. Pringle in 1923. Here not only the whole Inferior Oolite 

was found to be missing, but the Upper Lias also, leaving a thin representative 

of the Great Oolite Series resting directly on the Marlstone. 1 

(b) The Lincolnshire Limestone Area 2 

At the eastern end of the line just indicated as marking the southern 

boundary of the Scissum Beds, the strike of the rocks turns in a more northerly 

direction and intersects the line obliquely. Therefore similar conditions are 

no more to be expected in passing northward along the outcrop. Henceforth, 

in fact, instead of only Scissum Beds, other zones of the Inferior Oolite are 

met with in regular succession. 

Northward through Lincolnshire the outcrop crosses a basin of deposition 

in which thick deposits of Lower, Middle and probably Upper Inferior 

Oolite were laid down. They first appear at Kettering and, thickening rapidly 

northward, reach a maximum of over 100 ft. at Sleaford, 16 miles south of 

Lincoln. Beyond they become thinner once more, and continue to attenuate 

steadily towards the Market Weighton Axis. 

This great lens of Inferior Oolite deposits is known as the LINCOLNSHIRE 

LIMESTONE. Its age was not even approximately ascertained until after 1870, 

when the classic investigations of Samuel Sharp and J. W. Judd began to be 

published. Those pioneers showed independently that the Lincolnshire 

Limestone belonged to the Inferior Oolite, and the great bulk of it to the 

Lower and Middle divisions, but at the point where their investigations left 

off the subject still stands to-day. No more interesting line of research could 

be advocated than a detailed study of the Lincolnshire Limestone, but before 

results of any value could be obtained prolonged field work involving careful 

collecting would have to be undertaken, and a thorough knowledge of Jurassic 

palaeontology would be essential. 

The difficulties arise from bewilderingly rapid and frequent changes of 

facies, combined with what may be termed a general stratigraphical homogeneity. 

Thus the whole thickness, especially about Lincoln, may be a single, 

indivisible mass of limestone, or any part of it may become a 'rag' composed of 

corals, or pass into false-bedded banks of rolled shells. 

In places, Judd remarked: 'The patches of limestone rock . . . afford ample 

evidence of having once been coral-reefs; near Castle Bytham a pit is opened 

in a rock seen to be almost wholly made up of corals.' In other places the 

limestone 

'consists almost wholly of small shells or fragments of shells, sometimes waterworn 

and at other times encrusted with carbonate of lime. The shells belong to the genera 

1 J. Pringle, 1923, Sum. Prog. Geol. Surv. for 1922, pp. 126-39. 

2 Based on S. Sharp, 1870-3, 'The Oolites of Northamptonshire', Q.J.G.S., vol. xxvi, pp. 

354-93, and vol. xxix, pp. 225-302; J. W. Judd, 1875, 'Geol. Rutland', Mem. Geol. Surv.; 

and H. B. Woodward, 1894, J.R.B.y pp. 179-227.

INFERIOR OOLITE: LINCOLNSHIRE LIMESTONE 211 

Cerithium, Trochus, Monodonta, Turbo, Nerinea, Asiarte, Lima, Ostrea, Pecteny 

Trigonia, Rhynchonella, &c.; and spines and plates of Echinoderms, joints of Crinoids 

and teeth of fishes also occur abundantly in these strata, which exhibit much falsebedding. 

The Gastropods are usually waterworn and the specimens of Lamellibranchs 

and Brachiopods usually consist of single valves often broken and eroded. 

These beds it is clear were originally dead-shell banks, accumulated under the 

influence of constantly varying currents.' 1 

The conditions, therefore, were essentially similar to those so characteristic 

of the Corallian period, and to a lesser extent of the Great Oolite period also. 

The water was apparently shallower than in the Cotswold area, for coral reefs 

were able to grow more luxuriantly. Sputh Lincolnshire is perhaps to be 

compared rather with the strip that lay between the existing Cotswold deposits 

and the coast-line to the west, where all traces of Inferior Oolite have been 

removed by subsequent denudation. The shells in Lincolnshire are nearly all 

broken and rolled by the pounding of waves on the reefs, sand-banks, or 

beaches, while those in the Cotswolds are more often perfect, having been 

quietly entombed not far from where many of them lived and died. 

One of the principal obstacles in the way of detailed correlation of the 

Lincolnshire Limestone with other deposits is the extreme scarcity of ammonites. 

In this respect there is a likeness to the Cotswolds, but the dearth is 

far greater. In the Cotswolds the scarcity and frequently worn condition of 

ammonites give grounds for supposing that they are not autochthonous, but 

drifted in from outside. The sea in which the Lincolnshire Limestone was 

formed seems to have been still farther removed from the source of ammonites. 

The only contribution towards the dating of parts of the Lincolnshire 

Limestone based on modern palaeontological methods was made by W. H. 

Hudleston, in his monograph on the Inferior Oolite gastropods. Exclusively 

from a study of the gastropods he concluded that the lower portion of the 

limestone, which abounds in Ptygmatis (Bactroptyxis) cotteswoldice and sometimes 

in casts of the massive Natica cincta, is on about the horizon of the 

Oolite Marl and in part slightly earlier (murchisonce-bradfordensis zones). 

The highest beds, with masses of small rolled gastropods and other shells, 

of which the most famous sources are Ponton and Weldon, he assigned to a 

much later date, remarking that many of the species are not far removed from 

Great Oolite forms. Certainty in identifications is rarely possible, however, 

owing to the small size and worn condition of the specimens. 2 Provisionally 

it may be assumed that the highest part of the Lincolnshire Limestone is 

probably of Upper Inferior Oolite date. 

Recognition of intervening horizons has not proceeded very far. The 

Survey recorded an ammonite, 'A polyacanthus\ from a limestone known as 

the Silver Bed at Lincoln, and this Buckman stated to be a definite indication 

of the discites zone. 3 The same bed yielded Natica cincta, which Hudleston 

took to be an indication of the Oolite Marl (bradfordensis zone), but this may 

possibly have been derived. The level of the Silver Bed is only 8-10 ft. from 

the base of the Lincolnshire Limestone, and there is a 6-in. pebble-bed at the 

junction with the Northampton Sands. 4 It therefore seems likely that on this 

1 J. W. Judd, 1875, 'Geol. Rutland', Mem. Geol. Surv., pp. 139-40. 

2 W. H. Hudleston, 1888, 'Mon. Inf. Ool. Gastropoda', Pal. Soc., pp. 71-3, and 196. 

3 S. S. Buckman, 1911, Proc. Yorks. Geol. Soc., N.S., vol. xvii, p. 205, footnote. 

4 H. B. Woodward, 1894, J.R.B., pp. 216, 217.


northern side of the basin of deposition the discites zone overlaps the lower 

zones, evidence once again of the Bajocian Transgression. 

Concerning the detailed stratigraphy little can be said, owing to the doubtful 

relations of the rocks seen in the various exposures. 

The Lincolnshire Limestone first makes its appearance as a thin seam above 

the Northampton Sands near the old mill on the River Ise at Kettering, and 

it is also first met with westward in about the same latitude in outliers about 

Maidwell. The places of its first appearance farther east are considerably more 

to the north, Upper Estuarine Clays (Great Oolite Series) remaining in contact 

with Northampton Sands along both sides of the Nene Valley as far as 

Oundle. At Elton, 4 miles north-north-east of Oundle, the limestone first 

appears on the west bank of the valley only, and it is again found in rudimentary 

development at Castor. These points, when joined, are seen to lie 

on a curve, running at first nearly W-E. then SW.-NE., approximately parallel 

to the feather-edge of the Scissum Beds as delineated in the last section (see 

fig. 38, p. 207). 

To the west and north of its first appearance, under the hills of Rockingham 

Forest, the Lincolnshire Limestone thickens rapidly. At Geddington, 3 miles 

north-east of Kettering, it is 15 ft. thick, and near Cottingham, 4 miles farther 

north, it is 25 ft. thick; this, however, is near the edge of the outcrop, where 

the full thickness is not represented, and at Weldon, the same distance from 

Kettering but farther down the direction of dip, it measures 30 ft. Only 6 miles 

east of Weldon, at Oundle, there is no trace of the rock. Farther north-east 

the Lincolnshire Limestone passes in thick development under the Upper 

Jurassic formations, showing that the axis of the trough in which it was 

deposited lay obliquely across the present outcrop. 

The earliest horizons to appear seem to be the lowest, and at first, in all the 

sections in the district of Rockingham Forest, the principal palaeontological 

feature is a bed full of Ptygmatis (Bactroptyxis) cotteswoldice and Nerinea 

subcingenda Hudl. At or below this level occurs the Natica cincta, and 

numerous lamellibranchs and other fossils not sufficiently identified to satisfy 

modern requirements. 

In a small area less than 10 miles in diameter, from Deene (5-^ miles westnorth-west 

of Oundle) to Stamford, occur the COLLYWESTON SLATES. These 

can be regarded either as the base of the Lincolnshire Limestone or as the top 

of the Northampton Sands. They are worked in underground galleries reached 

by ladders down vertical shafts. When first raised the rock is a hard, solid 

stone, frequently blue-hearted, the faculty for splitting along bedding laminae 

being induced by exposure to frost. The resulting slates consist of a finegrained 

calcareous sandstone, highly fissile, the bedding planes covered with 

shells, principally Gervillia acuta Sow. and Trigonia compta Lyc. They bear a 

strong resemblance to the slates of Stonesfield, and like them contain plant 

remains and small fish teeth and scales, but none of the interesting mammalian 

and saurian bones so characteristic at Stonesfield. 

The bed from which the Collyweston Slates are obtained is only some 3 ft. 

in thickness. Between it and the Lincolnshire Limestone are one or more 

beds of sand with concretions, the detailed succession being extremely 

variable. 

The NORTHAMPTON SANDS beneath are usually from 20 ft. to 30 ft. thick,

INFERIOR OOLITE: LINCOLNSHIRE LIMESTONE 213 

but in one locality south-west of Stamford, about Barrowden and Wakerley, 

they thin out completely, leaving Lincolnshire Limestone for a short distance 

resting on Upper Lias clay. 1 This locality is about 10 miles east-north-east of 

that where the Marlstone df the Middle Lias is wanting, between Hallaton 

and Keythorpe, near the line of the Charnwood Axis (see p. 81). No axis 

has so far been suggested to account for this non-sequence. 

The Lincolnshire Limestone of the neighbourhood of Stamford, according 

to Samuel Sharp, reaches a thickness of 65-75 ft- The upper beds have been 

extensively quarried round an argillaceous tract situated on Upper Estuarine 

Clays, called Stamford Lings, and also at Ketton, where they yielded large 

quantities of excellent freestone. These exposures show horizons at and near 

the top of the series, and their age has not been determined. 

At Barnack, east-south-east of Stamford, a celebrated stone called Barnack 

Rag was already being obtained 500 years ago and has been used in several 

abbeys and cathedrals; but there appear to be no noteworthy exposures now 

left open. The rock consists of masses of corals and shells, and according to 

Judd it lies at the base of the series, close above the Collyweston Slate. This is 

borne out by the occurrence of Natica cincta. 

Farther north, at Great and Little Ponton, south of Grantham, fine sections 

of the Lincolnshire Limestone were exposed in the middle of last century in 

the making of the Great Northern Railway. Morris, who described the 

cuttings, 2 believed the beds to be Great Oolite and consequently, against the 

better judgement of Lycett, a number of the fossils were figured in their 

'Monograph on the Mollusca from the Great Oolite 5 (1850-4). The principal 

fossil-beds are near the top of the Lincolnshire Limestone, and Hudleston, 

from a study of the gastropods, suggested a tentative correlation with the 

similar beds at Weldon, but pointed out that the faunas showed certain marked 

differences. 3 

The most extensive freestone quarries anywhere in the Lincolnshire Limestone 

are still actively worked at Ancaster, north of Grantham. The freestone, 

like that at Ketton and elsewhere, is at the top of the series and its zonal 

position is unknown. The Upper Estuarine Clays of the Great Oolite Series 

as usual lie unconformably upon it. Ancaster and Sleaford lie in the centre of 

the trough of deposition, where the Lincolnshire Limestone reaches 100 ft. in 

thickness. A maximum measurement of 104 ft. was obtained in a boring. 

Between Grantham and the Humber the Lincolnshire Limestone builds the 

peculiarly straight and abrupt escarpment of Lincoln Edge, known locally as 

The Cliff. Running due north and south along its summit is the Roman 

Ermine Street. About Lincoln the thickness is 60-70 ft., but although there 

are several deep exposures, the homogeneous succession of limestones has 

yielded little of interest or value for correlation purposes except the ammonite 

of discites date in the so-called Silver Bed building-stone. 

In the strip of outcrop between Lincoln and the Humber 4 the beds begin 

to be differentiated into buff or cream-coloured oolites above, sometimes 

false-bedded and fissile, and grey, fine-grained cementstones, in appearance 

1 J. W. Judd, 1875, 'Geol. Rutland', Mem. Geol. Surv., pp. 91, 95. 

2 J. Morris, 1853, Q.J.G.S., vol. ix, pp. 324, See. 

3 W. H. Hudleston, 1887, 'Mon. Inf. Oolite Gastropods', Pal. Soc., pp. 72-3. 

4 Hence based on W. A. E. Ussher and C. Fox-Strangways, 1890, "Geol. N. Lines.', Mem. 

Geol. Surv., pp. 59-79, and A. J. Jukes-Browne, 1910, Geol. in the Field, pp. 496-500, &c.


like Blue Lias, below. These two series are separated by from 3 to 8 ft. of 

marl or clay. During the survey it was found convenient to name the upper 

series HIBALDSTOW BEDS, after the village of that name down the dip slope, 

and the lower series KIRTON BEDS, after Kirton Lindsey, situated on the edge 

of the escarpment. The division is a purely local one, however, and certain 

parts of the upper series resemble the lower and vice versa. Little has been 

found to distinguish them palaeontologically, though the occurrence of 

abundant Trigonia hemispheric a Lyc. in the intervening marl is interesting, 

for this species occurs in the Cotswolds only in the Lower Trigonia Grit 

(

INFERIOR OOLITE: MARKET WEIGHTON AXIS 2I5 

in some part of the Lower Estuarine Series of Yorkshire, but the sequence 

south of the Market Weighton Axis is condensed and incomplete. The correlation 

of the Ironstone Series with the Dogger (sensu stricto) is much more 

certain, and provides a useful datum. 

VI. THE MARKET WEIGHTON AXIS 1 

The continuity of the Lincolnshire Limestone under the Humber is attested 

by an outcrop in the river, forming a reef known as Brough Scalp. When it 

reappears on the opposite side, the limestone is still 20-30 ft. thick and is the 

most conspicuous and best-known member of the Jurassic rocks between the 

Humber and Market Weighton, forming a noticeable ridge past South Cave, 

Newbald and Sancton. It finally disappears beneath the Chalk east of Market 

Weighton, undiminished in thickness. 

Along this ridge the limestone has been extensively quarried under the name 

Cave Oolite. It is a hard, blue-centred, oolitic limestone when freshly exposed, 

but it soon weathers to a white, friable, oolitic sand. The upper division 

frequently shows false bedding, like the Hibaldstow Beds, while the lower 

division was proved in a boring at Brantingham Grange to consist of highly 

calcareous mudstone or cementstones like those in the Kirton Beds. 

Palaeontologically the limestone yields no more information than in Lincolnshire. 

The principal fossil is a polyzoan, Spiropora (= Millepora) straminea 

(Phil.), which in the Cotswolds occurs most abundantly in the Lower Trigonia 

and Buckmani Grits (discites zone), although it is also found in the Pea Grit. 2 

The lower beds, between the limestone and the Upper Lias, are also a 

direct continuation of those in North Lincolnshire, and are equally liable to 

rapid variation. The hard, brown ferruginous basal sandstone was pierced 

in the Brantingham boring, where it was 2 ft. 8 in. thick, while near by, at 

Ellerker, it gives place to a thin seam of fossils (none of stratigraphical value). 

The rest of the Northampton Sands consists chiefly of clays and sandy shale 

or shaly sandstone. In the northern part of the outcrop south of the axis, 

about Newbald and Sancton, a conspicuous band of hydraulic clay-limestone 

appears, similar to a band on the north side of the axis, and probably identifiable 

with one or more of the bands at the base of the Kirton Beds. 

The Inferior Oolite is totally obscured by the Chalk for rather more than 

10 miles north of Market Weighton. On first reappearing near Kirkby 

Underdale its most conspicuous features are again the limestones, which, 

although thinner than where last seen south of the axis, are similar in appearance. 

Beneath is a thin series of shales and sands, the beginning of the Lower 

Estuarine Series, with at the base traces of a ferruginous rock that expands 

northward into the Dogger. The extreme thinness of the component parts of 

the Inferior Oolite proves that the axis was an active factor in controlling 

sedimentation. (For further details see p. 64.) 

VII. THE YORKSHIRE BASIN 3 

When traced north-westward away from the Market Weighton Axis, the 

Inferior Oolite as a whole thickens rapidly, although the limestone divisions 

become thinner and die out. 

1 General stratigraphy, thicknesses, &c., based on C. Fox-Strangways, 1892, J.R.B. 

2 L. Richardson, 1911, Proc. Yorks. Geol. Soc., N.S., vol. xvii, p. 201. 

3 General stratigraphy based on C. Fox-Strangways, 1892,J.R.B.


The Lincolnshire Limestone or Cave Oolite reappears at Kirkby Underdale 

and at first, in the neighbourhood of the Derwent Gorge, it is the most 

important member of the series. Owing to its having been extensively quarried 

about Whitwell it is here known as the Whitwell Oolite. The quarries show 

30 ft. of thick-bedded, blue-centred oolite, used for road metal and lime, above 

which are 20 ft. of siliceous limestones and sands, weathering into large 

doggers or tabular slabs. 

Westward along the Howardian Hills the limestone thins down to 20 ft. at 

Terrington and is only 10 ft. thick at the west end, where all that is left is a 

hard siliceous limestone-band with marine fossils, weathering into huge 

tabular masses overhanging the beds below. North of the Coxwold faults it 

becomes nothing more than a false-bedded white grit with a calcareous 

cement, containing occasional wedges of comminuted shells and crinoid 

remains. Beyond Kirkby Knowle, 6 miles north of the Coxwold faults, it is 

no longer traceable. 

The basal bed of the Inferior Oolite, called throughout Yorkshire THE 

DOGGER, and probably corresponding fairly closely with the Northampton 

Ironstone Series, does not increase appreciably in thickness. At the Derwent 

it is 12 ft. thick and consists of ferruginous sandstone, the lower part calcareous 

and full of pebbles. Attempts have been made to work it for iron, but it has 

proved too poor an ore to repay commercial exploitation. Along the Howardian 

Hills its occurrence is very irregular, and for 10 miles it is absent altogether. 

At the west end it is a massive ferruginous limestone, and beyond the Coxwold 

faults it is sometimes unrecognizable and sometimes conspicuous as a 

5 ft. band of calcareous ironstone. It so continues, with many changes, around 

the Yorkshire Basin. 

The great increase in the thickness of the Inferior Oolite is therefore not 

due to the calcareous elements, but to the sandstones and shales between and 

above them—the so-called Estuarine Series. As the limestones die away, so the 

great 'estuarine' (really deltaic) beds thicken, until on the north side of the 

basin they dominate completely and become the most characteristic member 

of the Yorkshire Oolites, forming the greater part of the Cleveland Hills and 

the North York Moors, with a total thickness of 400-500 ft. 

The lithological appearance of these rocks and the scenery to which they 

give rise both recall strongly the Millstone Grit or Coal Measures. To one 

accustomed to the subdued and wooded scenery of the oolitic areas of Southern 

England and particularly to the fertile red fields and stone walls of the Cotswolds, 

it is difficult to realize that these barren, heather-clad moors are built 

of rocks of the same age as the familiar Oolites of the South. 

It is interesting to trace the expansion of the LOWER ESTUARINE SERIES, 

which separates the Dogger from the Whitwell Oolite. Almost as soon as it 

appears on the north side of the axis it is thicker than on the south, being 

already 50 ft. thick at Acklam, while in the Howardian Hills it soon reaches 

120 ft. A band of hydraulic limestone, correlated with that to the south of the 

axis, forms a conspicuous feature in the series from Burythorpe to the west 

end of the Howardian Hills. It consists of hard, close-grained argillaceous 

limestone, light blue-grey in colour, with a conchoidal fracture, and it has a 

thin band of ironstone below it. 

North of the Coxwold faults the hydraulic limestone gradually passes into

INFERIOR OOLITE: YORKSHIRE BASIN 217 

a sandstone and the ironstone below contains a few marine fossils. Northward 

among the moors the ironstone band multiplies, and in places has even been 

worked as an ore, while such marine fossils as Astarte, Trigonia, Pleuromya, 

Pholadomya, and Ostrea, unidentifiable specifically, are always associated with 

it. This marine horizon is called the ELLER BECK BED, after a locality near 

Goathland, where it is well exposed and especially fossiliferous. 

The most important difference marking off the Inferior Oolite north of the 

Market Weighton Axis from that to the south is the addition of two more 

series of beds above the Whitwell Oolite. 

Between Market Weighton and the Humber some 20 ft. of sands and clays 

separate the Cave Oolite from the Kellaways Rock. Almost nothing is known 

of them, but they are considered to represent the Upper Estuarine Beds 

(Great Oolite Series) which everywhere south of the Humber rest nonsequentially 

upon the Lincolnshire Limestone. 

North of the Market Weighton Axis the Whitwell Oolite is succeeded by 

similar estuarine beds full of plant remains and coal seams (the MIDDLE 

ESTUARINE SERIES), and those in turn by a marine horizon (the SCARBOROUGH 

BEDS or GREY LIMESTONE SERIES) which has yielded on the coast ammonites 

of blagdeni date. Above this follows another thick mass of unfossiliferous 

sandstones (the Upper Estuarine Series), more than enough to represent the 

Great Oolite. The full Inferior Oolite sequence is therefore as follows: 

lincolnshire 

Lincolnshire Limestone 

(Cave Oolite of S. Yorks) 

Northants j Variable Beds • 

Sands|T , 0 

I Ironstone Series 

yorkshire basin dates 1 

Scarborough Beds (max. 70 ft.) blagdeni (in part) 

Middle Estuarine Series 

(100 ft.) 

Whitwell Oolite and Millepore 

Series (0-50 ft.) discites 

Lower Estuarine Series (max. 

286 ft.) (with Eller Beck Bed) 

The Dogger (usually 5-20 ft.) murchisonce 

The difficulties of correlation are obvious. The dating of the highest marine 

series at Scarborough (at least in part) to the blagdeni zone provides a useful 

upward limit. But owing to the lack of significant fossils in the Lincolnshire 

Limestone we cannot be sure whether the whole of that limestone is represented 

in the Cave and Whitw T ell Oolites, or whether the Middle Estuarine 

Series is an intercalation in its upper portion, accompanied by great expansion. 

The similarity of the upper part of the Cave and Whitwell Oolites to the 

Hibaldstow Beds and of the lower part and the hydraulic limestone to the 

Kirton Beds, however, makes it extremely probable that the Middle Estuarine 

and Scarborough Series are additions to the Yorkshire sequence which have 

been removed south of the Market Weighton Axis, or were never deposited. 

These higher strata first appear near Westow, between Burythorpe and the 

Derwent. The Middle Estuarine Series reaches 20 ft. at the Derwent, 30-40 ft. 

at Terrington, and 60 ft. at the west end of the Howardians. Farther north it 

thickens less rapidly to its maximum of 100 ft. in North Yorkshire. It is at 

first a soft sandy rock with lenticles of dark shale and carbonaceous clay, the 

whole much like Coal Measures. North of Kirkby Knowle more massive 

beds of sandstone are a feature. 2 

1 L. Richardson, 1911, Proc. Yorks. Geol. Soc., N.S., vol. xvii, pp. 185-6. 

2 C. Fox-Strangways, 1892,J.R.B., pp. 217-27. 

Q


Workable coal-seams are found in many places on the moors both north and 

south of Eskdale, and in the Howardian Hills, especially about Coxwold. They 

seldom exceed 6 to 12 in. in thickness, but seams have been known measuring 

2 ft., and in both the Lower and Middle Estuarine Series seat-earths frequently 

occur below them. Plants are the chief interest of the Middle Estuarine Series: 

several localities where the beds are exposed, such as Marske and Roseberry 

Fig. 39. Stems of Equisetites columnaris (Brong.) with rhizomes attached; Lower Estuarine 

Series, Peak Alum Works, York9. (From Halle and Kendall, 1913, Geol. Mag. [5], vol. x, 

fig. 1.) 

Topping in Cleveland, and Gristhorpe Bay on the coast, have become famous 

throughout the palaeobotanical world. 

The flora is characterized principally by an abundance of ferns, cycads and 

certain types of conifers. The Ginkgoales too play a prominent part, as also 

the Equisetums, closely allied to the modern horse-tails. 

The majority of the plants have been drifted (even if only a short distance) 

to the positions where they are now found, but Dr. Halle and Prof. Kendall 

have obtained proof that at least some of the well-known upright Equisetites 

stems were entombed by sediment as they stood, rooted in the delta marsh. 

In the Lower Estuarine Series at the Peak Alum Works they found 

examples standing upright with long rhizomes growing out from the base in 

a horizontal direction (fig. 39). 1 Other plants found growing in situ at the base 

of the Inferior Oolite near the Yellow Sands at Whitby have been described as 

the remains of 'a forest of Dadoxylon\ and the roots have been traced ramifying 

in the shales of the Upper Lias. 2 These discoveries throw extremely 

interesting light on the conditions under which the Estuarine sandstones were 

laid down; especially since Dr. Bather has explained certain associated tubular 

markings as undoubtedly the U-shaped burrows of Polychaet worms (fig. 40), 

and Mr. Stather has even found their heaps of castings. These worms, which 

have been named Arenicolites statheri, lived in colonies on intertidal flats, 

moving constantly towards the surface as their burrows became covered with 

1 T. G. Halle and P. F. Kendall, 1913, Geol. Mag. [5], vol. x, pp. 3-7. 

2 The Naturalist, 1930, pp. 186-7; and P. F. Kendall, Q.J.G.S., vol. lxxxv, p. 438.


sand. 1 In the Lower Estuarine Series there are also beds of the earliest British 

Unio, U. kendalli Jackson. 2 

The most important work on the Jurassic plants in recent years has been the 

investigation by Mr. Hamshaw Thomas into the nature of certain minute 

carpels, fruits, seeds, anthers and pollen found in the Middle Estuarine plant 

bed in Gristhorpe Bay, and now shown to belong to a new class, the earliest 

Alive 

ÂRENICOLITES 

5TATHERJ 

nah size) 

Dead orqone ARENICOLOIDES(£nar.;ize) 

FIG. 40. U-shaped worm-burrows in the Lower Estuarine Series near Blea Wyke, Yorkshire. 

The left-hand drawing shows the Arenicolites worm within the burrow, with its head on the 

left and tail on the right. A current of water with sand and organic matter is drawn in for 

food, as shown by the arrows; above the other vent a casting has just been left. In the abandoned 

burrow the left-hand tube has become filled with sand and the bottom of the U has 

sunk in, causing the laminae above to sag and produce a depression at the surface. 

In the compound burrows on the right, the animal has moved to successive levels as shown 

by the arrows. (From F. A. Bather, 1925, Proc. Yorks. Geol. Soc., vol. xx, p. 188.) 

Angiosperms yet known. Under the name Caytoniales the class has been 

known and its Angiospermous affinities have been suspected for a number of 

years. Two species of two genera have now been described as Caytonia 

sewardi and Gristhorpia nathorsti. 

Mr. Hamshaw Thomas has summed up his views on these plants as follows: 

'The Caytoniales possess two of the features most characteristic of the modern 

flowering plants, viz., the closed carpel with a stigma, and the anther with four 

longitudinal lobes. On this account it seems permissible to group them with the 

modern Angiospermae, though they do not seem to resemble any modern family. It 

is possible that they belong to a line of evolution which was quite distinct from that 

which gave rise to the modern Dicotyledons and Monocotyledons, and represent 

a parallel series of forms now completely extinct.... The Caytoniales seem to occupy 

a position between the Palaeozoic Pteridosperms and the recent Angiosperms, and 

1 F. A. Bather and J. W. Stather, 1925, Proc. Yorks. Geol. Soc., vol. xx, pp. 182-99. 

2 J- W. Jackson, 1911, Naturalist, pp. 211-144


thus they suggest a possible solution for one of the great outstanding problems of 

evolution/ 1 

The constant association of the remains of the Caytoniales with the peculiar 

leaves known as Sagenopteris, which show venation similar to that of some 

dicotyledonous leaves, is believed to indicate that these were parts of the same 

plants. The two have also been found together in the Rhaetic plant-beds of 

Greenland. 

Mr. Hepworth has described infilled river or stream channels ('washouts') 

in the Lower and Middle Estuarine Series and notes that the drifted plants 

are most abundant in the base of these channels. 2 Similar phenomena will be 

more fully discussed in connexion with the Upper Estuarine Series (p. 315). 

The highest member of the Yorkshire Inferior Oolite, the SCARBOROUGH 

BEDS or GREY LIMESTONE SERIES, named after the best-known occurrence on 

the coast, begins as a very thin band, scarcely traceable before the Derwent. 

The first good sections, at Stonecliffe Wood 3 and in Cram Beck, near the 

Derwent gorge, show soft sands with doggers and several bands of siliceous 

limestone crowded with fossils. The principal forms are Pseudomonotis 

lycetti Rollier (= braamburiensis pars, auct.), Trigonia signata Lyc., Gervillia 

scarburgensis Paris, Pleuromya securiformis (Phil.), with Pectens, oysters, &c. 

The first two species are abundant in and characteristic of the Hook Norton 

Beds of Oxfordshire (see p. 303), and it is significant that Trigonia signata has 

not been recorded from below the Upper Trigonia Grit (garantiana zone) 

elsewhere in England. 4 Records do not suffice to show the range of the 

Pseudomonotis, but the combination of these two species may indicate that the 

beds in part represent the Hook Norton Beds. 

In the Howardian Hills the Scarborough Beds consist of two parts. Above 

are 20 ft. of brown porous grit, full of casts of Pseudomonotis lycetti, or a soft 

sandrock with doggers, abounding in the same fossil; below are 20 ft. of hard 

siliceous limestone, splitting into slabs, and sometimes so fissile as to have 

been used as roofing slates. 

Beyond the Coxwold faults thickening continues and thenceforth along the 

escarpment of the Hambleton and Cleveland Hills and across the moors to the 

sea there are three distinct divisions: a predominantly shaly division above, 

a predominantly arenaceous division in the middle, and a predominantly 

calcareous division below. The maximum thickness of the three portions 

together is probably 90 ft. Each is subject to considerable local variation. 

Thus at Spindle Thorn, on Spaunton Moor, a noticeable 5 ft. bed of hard 

blue limestone is intercalated in the lower part of the upper or shaly division. 

Richardson has called this the Spindle Thorn Limestone. Again, he has 

distinguished as Lambfold Hill Grit a thick fossiliferous grit at a higher horizon 

in the shaly division. This forms an important capping to many of the ridges 

and watersheds between the interior dales. 5 

By far the finest sections of the Yorkshire Inferior Oolite are, of course, on 

the coast, where the same SE.-NW. thickening can be traced as along the 

1 H. Hamshaw Thomas, 1925, Phil. Trans. Roy. Soc., vol. ccxiii. B, p. 356. 

2 E. Hepworth, 1923, Trans. Leeds Geol. Soc., part xix, pp. 24-8. 

3 Described as one of the principal Cornbrash exposures in Blake's 'Monograph of the Fauna 

of the Cornbrash', Pal. Soc., 1905, p. 16. But see C. Fox-Strangways, 1892,J.R.B., p. 249. 

4 J. Lycett, 'Mon. Brit. Foss. Trigoniae\ Pal. Soc., p. 29; and Appendix, pp. 1-10. 

5 L. Richardson, 1911, Proc. Yorks. Geol. Soc., vol. xvii, p. 197.


inland escarpment. It should be remembered that the most southerly cliffsections, 

in Gristhorpe Bay, between Scarborough and Filey, are little farther 

from the Market Weighton Axis than are the exposures in the neighbourhood 

of the Derwent gorge. 

To the foregoing account of the formation inland a summary of the sequence 

displayed along the coast may be usefully appended. 

SUMMARY OF THE INFERIOR OOLITE OF THE YORKSHIRE COAST 1 

Blagdeni Zone (Zigzag ? to sauzei ?) (SCARBOROUGH BEDS). The Scarborough 

Beds first rise from beneath the Upper Estuarine Series in Gristhorpe 

Bay. At the east end they measure only 3 ft., but before reaching the west end 

of the bay they have already more than doubled in thickness. The rock is a 

grey crumbly shale, with two bands of ironstone nodules, and the characteristic 

Pseudomonotis lycetti abounds. 

At White Nab, Cayton Bay, the thickness is 30 ft., and when Cloughton 

Wyke is reached, north of Scarborough, it exceeds 70 ft. The same Pseudomonotis 

is abundant, together with Trigonia signata, while one band near the 

base is crowded with Gervillia scarburgensis Paris. 2 Progressively with the 

thickening, a tripartite division becomes perceptible, as in the western escarpment. 

North of Scarborough all the sections show predominantly argillaceous, 

arenaceous and calcareous divisions, from above downwards. The argillaceous 

division, consisting of shale with some ferruginous bands, is here the thickest 

and to it is confined the Pseudomonotis. Thirty-seven feet from the top a bed 

has yielded Isocrinus, a fossil which in the moors to the north-west forms a 

thick grit-band about this horizon, known as the Crinoid Grit. 

Although the exact horizons of the ammonites recorded from the Scarborough 

or Grey Limestone are not known, it may be presumed that most if 

not all came from the lowest or limestone division. The available specimens 

in Scarborough Museum and from other sources were investigated in 1909-11 

by Buckman, who identified the following species: Skirroceras triptolemus 

(Bean MS.) (= Am. braikenridgei Morris and Lyc. non Sow. et auctt.), 

Teloceras coronatum (Quenst.), Teloceras sp. (= Am. blagdeni Mor. and Lyc. 

non Sow.), Stemmatoceras subcoronatum (Oppel), Stepheoceras cf. zieteni 

(Quenst.), S. cf. pyritosum (Quenst.), and IDorsetensia spp. 3 

On the whole this evidence suggests approximately a blagdeni date, but 

a belemnite occurs rather commonly (B. ellipticus Miller) which is common in 

the sauzei zone in the Cotswolds. 

Witchelliae and ? Shirbuirniae Zones (MIDDLE ESTUARINE SERIES). The 

sands, sandstones, and shales comprising this division are already 40-50 ft. 

thick on first appearing in Gristhorpe Bay, while northward at Cloughton 

Wyke and Blea Wyke they thicken to 90-100 ft. The passage both upward 

and downward into the marine beds is gradual. No internal evidence for 

dating has been obtained, the only fossils being the plants (see p. 218). The 

best plant locality is in Gristhorpe Bay. 

Discites Zone (MILLEPORE SERIES OR WHITWELL OOLITE). The Whitwell 

Oolite is recognizable palaeontologically in the most southerly sections on the 

coast, in Cayton Bay, and again at Cloughton Wyke, north of Scarborough, 

1 Based on Fox-Strangways and on Richardson, loc. cit. 

2 See E. T. Paris, 1911, Proc. Cots. N.F.C., vol. xvii, p. 255. 

1 S. S. Buckman, 1911, Proc. Yorks. Geol. Soc., N.S., vol. xvii, pp. 205-8.


As in the western escarpment, it dies away towards the north, and cannot 

be traced beyond Robin Hood's Bay—somewhat north of its disappearance in 

the west. 

On the coast the horizon is not represented by an oolite, but by a variable 

series of sandstones, with, however, the same fauna as at Whitwell and Cave. 

The most conspicuous animal of all is the small polyzoan, Entalophora 

(= Spiropora or Cricopora or Millepora) straminea (Phil.), from which the 

series derives its name. 

In Cayton Bay the true Millepore Bed is composed of 15 ft. of hard calcareous 

sandstone, but the marine fossils continue upward through 25 ft. of 

additional ferruginous sandstone and sandy shale not found elsewhere. North 

of Cloughton the horizon rapidly becomes so sandy and unfossiliferous as to 

be rarely recognizable, while north of a line joining Robin Hood's Bay with 

Kirkby Knowle on the western escarpment the Middle and Lower Estuarine 

Series are in contact and inseparable. 

None of the fauna of the Millepore Series and Whitwell and Cave Oolite is 

very satisfactory for purposes of correlation. The lamellibranchs are nearly 

all species which range throughout the Inferior Oolite and have even been 

recorded under names supposed to show their identity with Bathonian species. 

Such species as Gervillia zchidbornei Paris and G. prcelonga Lyc., which occur 

in the discites zone in the Cotswolds, however, may have some significance. 1 

Richardson has also drawn attention to certain spinose Rhynchonellids of the 

genus Acanthothyris which seem to be common to the Whitwell Oolite, the 

Lincolnshire Limestone and the Buckmani Grit. 2 

Concava-Bradfordensis Zones (LOWER ESTUARINE SERIES). This series is 

more arenaceous than the Middle Estuarines, but its general aspect is similar, 

and the two floras are closely allied, though not entirely identical. 

The Eller Beck Bed, already described, first rises above sea-level at Iron 

Scar, a mile north of Cloughton Wyke, and thence northward is seen intermittently 

as far as the Peak Fault, again from Hawsker to Whitby, and at 

Kettleness and Hinderwell, where it turns inland. The continuity of this 

marine band as compared with the Millepore Series is remarkable. Its 

position is usually rather above the middle of the Lower Estuarine Series, 

which expands to a maximum thickness of 286 ft. at Blea Wyke. 

Murchisonae-? Scissum Zones (THE DOGGER). The basal marine band 

of the Yorkshire Inferior Oolite is best known on the coast, where its varied 

lithology has been described in the following words by Fox-Strangways : 3 

'It changes from a sandstone to a limestone or a valuable ironstone, and from a finegrained 

shaly bed to a nodular calcareous oolitic rock with little bedding. In some 

places it seems to form a passage between the Lias and the Lower Oolite, in others 

it rests on a distinctly eroded surface of the shales, while here and there it is itself cut 

out entirely by the Estuarine Sandstones, which rest immediately on the Alum 

Shale.' 

Sometimes, as at Blea Wyke, the base of the Dogger contains a bed full of 

Nerinea cingenda Phil., the gastropod found in the Northampton Ironstone 

as far away as the Oxfordshire border. At other places, as in the Peak Alum 

1 E. T. Paris, 1911, Proc. Cots. N.F.C., vol. xvii, pp. 237-54. 

2 L.Richardson, 1911,10c. cit., p. 202. 3 C. Fox-Strangways, 1892, J.R.B., p. 154.

north hawsker saltwick whit8y 

cheek 

FIG. 41. Diagrammatic section along the Yorkshire coast between Long Nab, north of Scarborough, and Whitby, to show the principal exposures 

of the Inferior Oolite Series. Total distance about 13 miles. Between the two sections, in Robin Hood's Bay, i| miles of low cliffs of Lower Lias 

covered by Boulder Clay are omitted. (Based on J. F. Blake, P.G.A., vol. xii, p. 116.)


Works near Blea Wyke, 5-15 ft. of sandstone is entirely unfossiliferous, though 

there are usually rolled pebbles, and sometimes ammonites, derived from the 

Upper Lias—a feature familiar in the Eastern Midlands. At least one fragment 

of an ammonite, of striatulum type, has been found partly embedded in a 

pebble of Upper Lias shale. 1 

A number of channels have been described, cut through the Dogger and 

deep into the Upper Lias prior to the deposition of the Lower Estuarine Series, 

FIGS. 42, 43. Diagrammatic representations of the sections at the eastern quarry, Boulby 

Alum Works (above), and in East Cliff, Whitby (below), illustrating channelling of the 

Upper Lias shales by the basement beds of the Inferior Oolite in Yorkshire. (After R. H. 

Rastall, 1905, Q.J.G.S., pp. 450,452, re-drawn.) 

thus proving renewed or continued earth movements after the formation of 

the Dogger, and even larger channels were cut earlier and filled by the Dogger 

(see figs. 42-3). One of the largest was described by Fox-Strangways inland 

at Vittoria Plantation, Bilsdale. The Dogger, which fills it to a thickness of 

50 ft., is there a 'ferruginous echinital limestone', largely composed of the 

spines of an Acrosalenia. Richardson has called attention to the fact that the 

Lower Limestone of the Edge, Painswick, Gloucestershire (which may be 

presumed to be of approximately the same age) is also full of an Acrosalenia 

—A. lycetti—and the remains of crinoids. 

In other places the Dogger contains a workable ironstone from 1 to 4 ft. 

thick, but in Rosedale as much as 14 ft. thick. It is of inferior quality, however, 

and has not been exploited to any great extent. An extraordinary 

development is found in Rosedale, where there are two channels (? or two 

sections of the same channel), 70 ft. deep, filled with a confused mass of 

irregular lumps of dark blue oolitic ironstone coated with dark brown or 

purplish iron oxide, the whole highly magnetic. If echinoid or other organic 

remains were ever present here, they have been obliterated. 2 

1 L. H. Tonks, 1923, Trans. Leeds Geol. Soc., part xix, p. 32. 

2 C. Fox-Strangways, 1892, J.R.B., pp. 170-1.

INFERIOR OOLITE: HEBRIDES 225 


The Lower, Middle, and Upper Inferior Oolite of the Inner Hebrides are 

entirely of marine origin, although the predominantly sandy sediments and 

the presence of a considerable amount of drifted wood indicate that they were 

formed in proximity to land. 

Palaeontologically the strata afford a remarkable contrast with those laid 

down at the same time in Yorkshire, or indeed anywhere north of the Mendip 

(or Keynsham) Axis; for some of the beds are crowded with autochthonous 

ammonites. All the zones of the Lower Inferior Oolite are condensed into 

a few feet of highly ammonitiferous beds, comparable only, among British 

deposits, with the ammonite beds of the Dorset-Somerset area and of Dundry 

Hill. The zones of the Middle Inferior Oolite, on the other hand, are greatly 

expanded, and fossils are much less plentiful, owing to their being dispersed 

through unusually great thicknesses of rapidly-deposited rock (600 ft. of 

sandstone in Raasay, over 300 ft. in Skye); but nevertheless ammonites of 

nearly every zone are present. The Upper Inferior Oolite (still, at first, with 

autochthonous ammonites) follows conformably and sequentially, but begins 

in most places with a rapid lithic change to shale and clay (see fig. 32, p. 184). 

The succession has been carefully re-examined in recent years by Lee, whose 

ammonite collections were submitted to Buckman and are now on view in the 

Royal Scottish Museum, Edinburgh. The exact lines of demarcation between 

most of the zones could not be determined, but the general succession of 

ammonite horizons and the approximate relative thicknesses of the zones were 

made out. The rest of the fauna has still to be studied. 

(a) Raasay and Skye 1 

The outcrops in both Raasay and Skye are extensive. In Raasay, where the 

formation is thicker than anywhere else in the British Isles, it builds the main 

precipices of the great eastern cliffs, and the scenery to which it gives rise is 

also probably the grandest Jurassic landscape in the country. In Skye the 

sandstones, only half as thick, but still measuring 300 ft., build the long line 

of cliffs, often capped with basalt, which form the eastern bulwark of Trotternish, 

both north and south of Portree Bay. In the peninsula of Strathaird 

the outcrop is chiefly heather-covered, forming a slope between the basalt 

plateau and the shore of Loch Slapin (map, p. 114). 

The bulk of the formation in both islands is made up of the Middle Inferior 

Oolite, which consists of rather soft, white-weathering yellow sandstone, 

locally developing large doggers—a type of deposit which never proves highly 

fossiliferous and undoubtedly testifies to relatively rapid accumulation. The 

thin ammonitiferous beds of the Lower Inferior Oolite, although so interesting 

palaeontologically, feature little at the surface and are not often well exposed. 

SUMMARY OF THE LOWER AND MIDDLE INFERIOR OOLITE OF RAASAY AND SKYE 

Blagdeni Zone. The topmost part of the sandstone in both islands is 

coarse and gritty and full of broken lamellibranchs. The whole series, although 

well exposed in the cliffs, is inaccessible, and most of the collecting has 

1 Based on C. B. Wedd, 1910, 'Geol. Glenelg, Lochalsh and SE. Skye', pp. 115-20; 

and G. W. Lee and S. S. Buckman, 1920, 'Mes. Rocks Applecross, Raasay and NE. Skye', 

pp. 44-50, 65, 72-9; Mems. Geol. Surv.


perforce to be done from fallen blocks. The greater part of the thickness 

seems to be characterized by Stephanocerates and allied ammonites of the 

blagdeni zone, usually flattened: Teloceras cf. coronatum (Quenst.), Stepheoceras 

sp., Stephanoceras sp., and Stemmatoceras cf. subcoronatum (Oppel) 

were recorded. 

Sauzei, Witchelliae and Shirbuirniae Zones. Below the sandstone cliff on 

the north side of Bearreraig Bay, Skye (PL X), the fallen doggers have yielded 

large numbers of Sonninice, denoting the sauzei zone, and single specimens of 

Witchellia and Shirbuirnia have also been obtained. The Shirbuirnia is a 

gigantic form measuring more than 18 in. in diameter, and was identified as 

S. trigonalis S. Buck. The Sonninice are comparable with swarms in the 

ironshot oolite of Dundry and the top part of the Sandford Lane fossil-bed 

near Sherborne, where they are associated with Otoites sauzei. The absence 

of Otoites in Scotland is noteworthy. 

Discites Zone. The discites zone has not been detected with any degree 

of certainty in Skye, but in Raasay a large number of small ammonites of 

discites date have been obtained at one locality only, on the Dun Caan path. 

Their restricted distribution suggests a lenticular deposit. 

Concava and Bradfordensis Zones. A few ammonites of the concava and 

bradfordensis zones were obtained in Raasay in the same blocks as numerous 

species of murchisonce date. Four species of Ludwigella are recorded, and 

three of Brasilia, including B. bradfordensis, the index-fossil. There are 

similar indications in Skye, below inaccessible cliffs between Holm and 

Bearreraig. The rocks whence specimens of Brasilia have dropped consist 

here of bluish shaly sandstone with doggers, situated 30-50 ft. above sea-level. 

It is possible that the zones are less condensed than in Raasay. 

Murchisonae Zone. Holm, in Skye, is the type locality of Ludwigia 

murchisonce, but it is rare there, although other ammonites of the same date 

are plentiful. The zone consists of a small thickness of flaggy sandstone, which 

forms the base of the sandstone series, cropping out between tide-marks on 

the south side of the mouth of the River Bearreraig. The ammonites, which 

belong to the genera Ludwigia, Ludwigina, Hyattina, Welschia, Strophogyria, 

Crickia9 and Brasilina, are extremely well-preserved and abundant, both here 

and at several points in Raasay (the best locality being beside the Dun Caan 

path). These outcrops prove that the murchisonce zone is more richly ammonitiferous 

in the Hebrides than at any other locality in the British Isles, excepting 

possibly Chideock, Dorset (the Wild Bed). Nevertheless, the absence of 

certain southern families is remarkable, especially the Hammatoceratidae— 

Hammatoceras, Erycites, &c. 

Ancolioceras Zone. The only indication of deposit of this date is the 

presence of cf. Ancolioceras substriatum Buck, in the scissum zone of Raasay. 

Scissum Zone. The scissum zone of Raasay consists of 8 ft. 6 in. of thinbedded 

limestones and shaly limestones, separating the shales below from the 

great sandstone series above. At the top of the zone on the path one mile 

south of Dun Caan is a band of limestone with lenticles crowded with small 

ammonites of scissum date. Thirteen species of Lioceras and one each of 

Canavarella, Ancolioceras, and Rhceboceras are recorded, but the characteristic 

genus Tmetoceras is wanting. 

A similar development of the zone occurs in Ardnadrochet Glen, Mull.

Photo. Geol. Survey. 

Bearreraig Bay, m. N. of Portree, Isle of Skye. 

Inferior Oolite sandstones overlain by sill of Tertiary columnar dolerite. 

Ammonitiferous Lower Inferior Oolite in foreground. 


Dun Caan and the east coast of Raasay from Rudha na'Leac. 

The high cliff consists of Inferior Oolite sandstone, with a slope of Great 

Estuarine shales above, capped by the Tertiary plateau basalt of Dun Caan. 

Lias and Rhaetics in foreground. 

PLATE XII

INFERIOR OOLITE: HEBRIDES 227 

(b) Mull and Ardnamurchan 1 

The Lower and Middle Inferior Oolite cover a small area in the south-east 

corner of Mull, about Loch Spelve and Loch Don, and they also occur on the 

south coast of the promontory of Ardnamurchan, as a faulted outlier a mile 

and a half south-west of Kilchoan. A former extension over the north of 

Ardnamurchan is proved by the presence of blocks in the agglomerate of a 

volcanic vent (map, p. 114). 

The thickness is much less than in the northern islands, not much exceeding 

90 ft. in Ardnamurchan and 80 ft. in Mull, but the succession, although contracted, 

is in essential features the same. The upper and by far the bulkier 

part of the formation consists of poorly-fossiliferous sandstones, the greater 

portion presumably of blagdeni age, while the thin lower beds are predominantly 

calcareous and yield abundant ammonites of many different 

zones. 

The most complete sections are on the shore at Port nam Marbh and Port 

Donain, Mull, supplemented a short distance inland by a useful section of the 

basal beds in a stream running through Ardnadrochet Glen, south of Loch 

Don. The Ardnamurchan exposure is an irregular one along the shore, 

extending about a mile on either side of Sron Bheag Point, and it is greatly 

complicated by intrusions and faulting. Nevertheless some of the zones are 

there more fully developed than in Mull, and Buckman claimed from them 

some support for the subdivision of the discites deposits which he advocated 

in his last years. 

SUMMARY OF THE LOWER AND MIDDLE INFERIOR OOLITE OF MULL AND 

ARDNAMURCHAN 

Blagdeni Zone. Contrary to the course of events in Skye and Raasay, 

sandstones continued to be deposited, at least in Mull, until after the immigration 

of the garantiana fauna of the Upper Inferior Oolite. Consequently 

there is no definite upper boundary to the blagdeni zone, which, in the absence 

of any sign of the niortensis zone, may be considered to extend upwards to the 

first occurrence of the genus Garantiana, 10 ft. below the shales of the Great 

Estuarine Series. Thus, if the same amount be subtracted from the top of 

the sandstone in Ardnamurchan, where Garantiana has not been found, as at 

Port nam Marbh in Mull, some 50 ft. of almost entirely unfossiliferous sandstone 

are left in both localities to represent the thick blagdeni zone of Skye 

and Raasay. 

Blagdeni, Sauzei, and Discites Zones. In Ardnamurchan the highest 

fossils found are ammonites of discites date, so that an unknown thickness 

of the unfossiliferous sandstone may possibly represent the intervening zones. 

That these zones should be developed to any considerable extent is unlikely, 

however, for at Port nam Marbh they are all compressed into a single bed 

1 ft. 6 in. thick. This highest fossiliferous bed consists of grey sandy limestone, 

in which specimens of Inoceramus are conspicuous. The Survey 

obtained from it three species of Dorsetensia, indicative of the blagdeni zone, 

1 Based on G. W. Lee, 1925, 'Pre-Tert. Geol. Mull, Loch Aline and Oban', pp. 98-112; 

and G. W. Lee and E. B. Bailey, 1930, 'Geol. Ardnamurchan', pp. 44-9; Mems. Geol. Surv.


a Sonninia cf. buckmani Haug, doubtfully suggesting the presence of the 

sauzei zone, and IBraunsina angulifera S. Buck., said to be indicative of the 

discites zone. 1 

Discites and Concava Zones. The discites zone at Port nam Marbh has 

a thickness of 3 to 4 ft., since its fauna, represented by a rich assemblage of 

ammonites, occurs also 18 in. lower, in the highest foot of a 6 ft. block of 

siliceous limestone, where it is mingled with a fauna of concava date. Buckman 

identified 33 species of ammonites from this level, including most of the 

principal characteristic forms, too numerous to cite. 2 In the Ardnamurchan 

section the two zones are much thicker and quite distinct. The discites zone 

comprises 15 ft. of baked blue shale or flags, weathering to a soft sandstone, 

overlying 4^ ft. of limestones with hard shaly layers. Buckman subdivided 

this zone into three horizons of Docidoceras, Reynesella, and Platygraphoceras, 

in descending sequence. The concava zone beneath is not continuously 

exposed, but it is probably at least 7 or 8 ft. thick. It yielded 

what Buckman considered to be ten species of Ludwigella, and four other 

genera. 

Bradfordensis Zone. In Ardnamurchan the bradfordensis fauna was 

recognized, partly segregated in a limestone band 2 ft. thick, and partly 

mingled in another block, 1 ft. 9 in. thick, with the Ludwigella assemblage. 

Besides Brasilia bradfordensis, several species of Brasilina were collected. In 

Mull the zone has not been separated, though some of its ammonites have 

been detected. 

Murchisonae Zone. The murchisonce zone is very rich in ammonites both 

in Mull and in Ardnamurchan, and in both places it is confined within a very 

small compass. In Ardnamurchan it is restricted to ft. of limestone and at 

Port nam Marbh to the lowest 1 ft. of the same block of siliceous limestone as 

that which yields in its highest foot the concava and discites assemblage. The 

ammonites include Ludwigia murchisonce, L. gradata S. Buck., Ludwigina, 

Crickia, Hyattia, Apedogyria, &c. 

Ancolioceras Zone. The only definite evidence for this zone hitherto 

found is a single specimen of Ancolioceras aff. cariniferum S. Buck, in Ardnadrochet 

Glen, and an immature and doubtful specimen of Ancolioceras in 

8 ft. of limestones in the Ardnamurchan section. But in the Ardnadrochet 

Glen there is an assemblage of fossils transitionary between scissum and 

murchisonce faunas, which are considered to show that the zone is separately 

represented. 

Scissum Zone. The scissum zone is well represented both by ammonites 

(Tmetoceras and Lioceras) and by brachiopods in Ardnadrochet Glen, but 

in the coast section at Port nam Marbh it has only been recognized by 

brachiopods—Rhynchonella subdecorata Dav. The rock (sandy limestone) in 

which the fossils occur is only some 3 ft. thick, but all or part of another 8 ft. 

of limestone above, in which no fossils have been found, may also belong to 

the zone. In the Ardnamurchan section a few feet of sandy beds at the base 

1 The Survey were not quite confident that the remarkable assemblage believed to have 

been obtained from this bed might not have been in some way brought together by faulting. 

'Geol. Mull, Loch Aline and Oban', 1925, p. 105, Mem. Geol. Surv. 

2 They are listed in the Survey Memoir, 1925, loc. cit., pp. 104-5. The 'species' are to be 

understood as bearing separate names according to Buckman's conception of genus and 

species.

INFERIOR OOLITE: KENT 229 

of the Inferior Oolite have yielded nine species of Lioceras belonging to the 

scissum zone, but no Tmetoceras. 


No Inferior Oolite is exposed in Eastern Scotland. 

X. KENT 

In the Kent borings Inferior Oolite was met with in only a few places and 

was often apparently absent and never completely developed. Nowhere was 

evidence obtained for the presence of either Lower or Middle Divisions. 

At several places sands with doggers were met with above the Lias, but they 

yielded lamellibranchs indicative of the Upper Inferior Oolite. The sands 

pass unconformably across the Lias on to the Palaeozoic platform in the north 

of Kent, suggesting that the Lower and Middle Inferior Oolite were removed 

during the Bajocian Denudation.

Zones (Plate XXXIV). j Dorset. 

Parkinsonia schloenbachi 1 

CHAPTER IX 

UPPER INFERIOR OOLITE 

! 

Microzoa and 

Sponge Beds. ^ ^ 

Massive Beds. 

Strigoceras truellei Truellei B e d ^ ^ ^ i 

Garantiana garantiana ' 

Astarte 

obliqua 

Bed. 

Dundry and \ 

Sherborne South North 

District. Cotszcolds. \ Cotswolds. 

Sherborne 

Building 

Stone. 

Strenoceras niortensis z Conglomerate. Niortensis j 

Bed. 1 

Rubbly Beds 

& Anabacia 

Limestones. Clvpeus 

Doulting 

Stone. 

Upper Coral 

Bed. 

Dundry 

Freestone. 

Grit. 

Trigonia 

ConglonvT^^^Grit. 

WE have already seen that the Middle Inferior Oolite period closed with 

the most important episode of orogenic movements that had occurred 

in England since the beginning of Jurassic times. After long ages of comparative 

quiescence, the E.-W. or Armorican anticlines revived their activity, 

and along the Mendip, North Devon, Weymouth, and Birdlip Axes the Lias 

and Lower and Middle Inferior Oolite were raised up in gentle saddles, 

probably in places high above sea-level (especially over the Mendips), 

everywhere at least within the range of wave or current action. When the 

epeirogenic subsidence that followed lowered both anticlines and synclines 

beneath the sea so that normal sedimentation was resumed, the crests of the 

anticlines had been planed off and the new Upper Inferior Oolite strata were 

deposited evenly across their basset edges. The period of erosion that occurred 

during the interval was called by Buckman the Bajocian Denudation, and the 

epeirogenic movement by which the denudation was brought to an end is 

known as the Vesulian Transgression. 

It is unfortunate that the term Inferior Oolite was universally used for the 

beds both below and above this important plane of discordance before the 

discordance was detected. Where Townsend (borrowing it from William 

Smith) first applied the term, in the country around Bath, the only part of the 

formation present is that above (namely the Upper Inferior Oolite), and so if 

any restriction were attempted, the remainder of the formation, described in 

1 Buckman assigned this to a new genus, Haselburgites Buckman; see T.A., 1924, vol. iv, 

pi. CDXCIII, and for definition of genus T.A.y 1920, vol. iii, p. 30; genotype H. admirandus 

S. Buck., figd. 1921, pi. CCIII. It would appear, however, that Dr. Spath rejects the genus; 

see 'Revis. Jurass. Ceph. Fauna of Kachh', Part IV, Pal. Indicay 1931, p. 280. 

2 Formerly considered the topmost zone of the Middle Inferior Oolite, but transferred by 

Prof. Morley Davies for reasons explained in this chapter. See P.GA.t vol.xii, 1930, pp.231-3. 

— 

—

UPPER INFERIOR OOLITE 231 

the previous chapter, would be the part to require a new name. 1 Certainly 

no better plane for separating two formations occurs in the Jurassic System, 

and the failure of our classification to take account of it is one of its worst 

shortcomings. 

D'Orbigny also ignored this important stratigraphical break. In spite of 

his protests against other geologists for being guided by lithology in grouping 

the rocks, he was swayed by the very same considerations, for he included in 

his Bajocian Stage all our Inferior Oolite up to the zigzag zone, or basal 

Fuller's Earth. Indeed, if we subtract the transgressive portion from the 

Bajocian of the type-locality of Bayeux in Normandy, very little is left. For 

this reason Norman geologists are emphatic that the Bajocian Stage must be 

kept intact, as d'Orbigny created it, 2 and the same conclusion is very forcibly 

impressed upon the observer on the coast of Dorset. When a broader view 

is taken, however, there seems every justification for dismembering the 

Bajocian and reviving for the overstepping portion Marcou's term Vesulian. 

Introduced in 1848, this term is no upstart, but can claim an antiquity equal 

to that of d'Orbigny's names. 

In England the only possible course is to describe the Upper Inferior 

Oolite separately, in a chapter of its own. Wherever we trace it in the southern 

counties it behaves independently of the rest, spreading over scores of square 

miles where the Lower and Middle divisions do not exist, overstepping the 

edges of the Lias and even the Carboniferous Limestone. In comparison with 

the thick and complex Great Oolite Series above, it is but a thin and homogeneous 

formation. It cannot even be traced with certainty beyond Oxfordshire. 

But it is not on that account by any means insignificant. If we wish to 

swell its bulk we had rather describe with it the Fuller's Earth and Chipping 

Norton Limestone, which are perfectly conformable with it, than the Middle 

and Lower Inferior Oolite; for they are a part of the same formation only 

in name. 


The full sequence of the Upper Inferior Oolite is exposed in the cliffs 

between Bridport Harbour and Burton Bradstock, and the section is amplified 

by quarries inland at Chideock Quarry Hill, Burton Bradstock allotments, 

Shipton Gorge, Walditch, Loders and other places. As already remarked, 

the- beds here are thick in comparison with the attenuated representatives 

of the Lower and Middle Inferior Oolite, although they probably took only 

a fraction of the time to form. 

The thickest zone is that of Parkinsonia schlcenbachiy which comprises 

4 ft. of white limestones, in places full of sponges and resembling the White 

Sponge Limestone on the same horizon in Normandy. Beyond this; in the 

cliff-sections, there is little else, and the total thickness is only just over 7 ft. 

As in Normandy, the White Sponge Limestone is separated from the Fuller's 

Earth Clay by two thin rubbly beds of limestone, which here would be more 

logically grouped, according to lithology, with the Inferior Oolite. They 

1 Cheltenham Beds was used for the whole Inferior Oolite up to the base of the Fuller's 

Earth, less the Yorkshire Dogger and basal Northampton Sands (scissum-murchisona-Ancolioceras 

zones) by Sir A. Geikie in 1885, Text Book of Geology, 2nd ed., p. 788. 

2 After a visit to Normandy and a conversation there with Professor Bigot I was so far 

convinced as to write that 'the abolition of the stage-name Vesulian . . . has now been generally 

decided upon' (P.GA., vol. xii, 1930, p. 407). 

854371 R


contain Zigzagiceras spp. and Oppelia fusca, however, and so belong rightly 

with the Fuller's Earth. 

SUMMARY OF THE UPPER INFERIOR OOLITE OF SOUTH DORSET 1 

Schloenbachi Zone. 

The schloenbachi limestones with sponges, ostracoda and foraminifera 

thicken from 4-J ft. at Burton Bradstock to nearly 14 ft. at Chideock Quarry 

FULLER'S I 

EARTH | 

THE 5CROFF" 

Z'GIAG BED"" 

M I CROIOA 

BE 05 

•SCHL0EN3ACHI 

?TRU ELLEl 

PSAUZEl 

] WITCHELL!/t 

BU R.TCN 

BRADSTOCK 

SCHLOENBACHI 

TRUELLEI BED 

LASTARTEBEO 

}RED BED 

SCISSUM BEDS 

FIG. 44. Comparative sections of the Upper Inferior Oolite in South Dorset. (After 

L. Richardson, 1927-28, Proc. Cots. N.F.C., vol. xxiii, pp. 51, 60, 17*1.) 

Hill. The lower beds are massive, even crystalline, and yield few fossils, 

while in the upper half of the zone some are marly and crowded with sponges, 

microzoa and polyzoa. The richest locality for polyzoa is the village of Shipton 

Gorge. No less than twenty-eight species of sponges have been recorded from 

the neighbourhood, many of which were figured for the first time by Hinde 

in his 'Monograph of the British Fossil Sponges'. Some of the principal genera 

are Holcospongia, Leucospongia, Peronidella, Platychonia, Tremadictyon, and 

Corynella. A number of echinoderms also occur, and the common Belemnopsis 

bessina and Sphceroidothyris sphceroidalis. 

Truellei Zone. 

The botton bed of the massive limestones—1 to 2 ft. thick—is the zone of 

Strigoceras truellei. It is not always distinguishable (e.g. at Shipton Gorge) 

but it can generally be recognized by an eroded upper surface, to which 

Serpulce are attached, and by a more or less continuous line of *S. sphceroidalis 

in the lower part. It has yielded, besides many other fossils, two ammonites 

of the genus Dimorphinites, which occur in the top of the Ironshot Oolite of 

Bayeux. 

Garantiana Zone. 

This zone is usually represented by a mere seam of fossils in a crumbly 

brown ironshot matrix, the Astarte obliqua Bed. It is crowded with lamelli- 

1 Based on L. Richardson, 1928-30, Proc. Cots. N.F.C., vol. xxiii, pp. 35-68, 149-85, 

253-64; and 1915, P.G.A., vol. xxvi, pp. 47-78.

UPPER INFERIOR OOLITE: SHERBORNE DISTRICT 233 

branchs, gastropods, and Belemnopsis bessina, and generally appears to be 

joined on to the top of the Red Bed of the Middle Inferior Oolite. A few miles 

inland, at Vetney Cross, the zone is 1 ft. thick, but on the coast at Burton 

Bradstock it averages only 4 in. 1 

Niortensis Zone. 

Below the Astarte obliqua Bed, on the coast, are local patches of a thin 

conglomerate containing remanie fossils of the underlying Middle Inferior 

Oolite. It rests upon an eroded and pitted 

surface of the Red Bed, of which its con- 

stituent pebbles are made up, together with 

' snuff-boxes' derived from that bed, and rolled 

ammonites of the blagdeni and sauzei zones. 

Besides these, however, there are some ammonites 

which both Buckman and Spath have 

identified as belonging to the niortensis zone. 

The conglomerate therefore belongs to the 

base of the Upper Inferior Oolite or to the time 

of the Bajocian Denudation which preceded 

the Vesulian Transgression, and it provides 

interesting evidence that somewhere in this 

neighbourhood during the niortensis hemera 

Middle Inferior Oolite was undergoing destruction 

and redeposition. 

The zones maintain essentially the same 

characters (except that the niortensis zone is 

absent, apparently overlapped) through North 

Dorset and over the Somerset border past 

Crewkerne, 2 until the outcrop bends eastward 

to Yeovil and Sherborne. The thickest zone 

throughout the district is always that of 

schloenbachi, which contains rich ostracod and 

foraminifera beds atMisterton and elsewhere, 

FUSCA %i 

ZIGZAG 

ZONES 

fUllEA.'S EARTH 

CLAY 

0STA.6A KNOHHl 

FIG. 45. Section at Stoford, near 

Yeovil, showing the abnormal reduction 

of the Inferior Oolite Series. 

(Based on S. S. Buckman, 1893, 

Q.J.G.S., vol. xlix, p. 484, with 

amendments by L. Richardson, 1932, 

Proc. Cots. N.F.C., vol. xxiv, p. 52.) 

and a sponge bed at Haselbury Plucknett. Its thickness varies from about 9 ft. 

in the west to 3 ft. in the east. At Misterton fourteen species of foraminifera 

have been recorded. The truellei zone can seldom be identified with certainty 

in the Crewkerne district, but, as on the coast, it is probably represented in 

the base of the Massive Beds. 

In the north-eastern part of the Dorset-Somerset area, from the neighbourhood 

of Yeovil to the Mendips, the development of the beds is at first sight 

very different from that on the coast. Although at Stoford the whole Inferior 

Oolite is almost incredibly compressed, the Upper Division occupying only 

a couple of feet in the quarry near the station (fig. 45), 3 a sudden thickening 

of limestones takes place east of Yeovil to 30 ft. at the Halfway House, between 

1 Buckman has figured a number of ammonites from the Astarte obliqua Bed of Burton 

Bradstock: Garantiana garantiana (TApi. CCCLVIII), Parkinsonia rarecostata (CCCLII), 

P. interrupta (cccxxxvn), &c., and also uncoiled ammonoids of the genera Plagiamites and 

Spiroceras. 

2 L Richardson, 1918, Q.J.G.S., vol. lxxiv, pp. 145-73; 1915, P.G.A., vol. xxvi, pp. 69-75. 

3 L.Richardson, 1911, P.G.A., vol. xxii, p. 262 and pi. xxxix.


Yeovil and Sherborne, and 45 ft. at Sherborne. Northward the limestones 

attenuate with equal abruptness and then maintain a steady 10-20 ft., usually 

10-15 ft., to the Mendips. 

The chief centre of interest lies naturally in the area of greatest thickening 

about Sherborne, and this coincides with the region in which some of Buckman's 

earliest researches were carried out, as mentioned in the preceding 

chapter. 1 It has more recently been carefully revised by Richardson, with 

interesting results. 2 

In the early days the whole of the 'Upper Inferior Oolite' of the Sherborne 

district was spoken of as the 'Top Beds' or Parkinsoni Zone, with the implication 

that it was of one date throughout. One of the first important results of 

Buckman's earliest stratigraphical work and the application of his new 

methods was to show that the Top Beds are of different dates in different 

parts of the district and that in general they are older in the east than in the 

west. He demonstrated that at the Halfway House, Compton, in the west, the 

30 ft. of poorly fossiliferous limestones constituting the Top Beds overlie the 

truellei zone, which is a 1 ft. fossil bed and rests in turn upon a thin, ochreous, 

marly representative of the garantiana zone, like the Astarte obliqua Bed of 

Burton Bradstock and full of the same fossils. He further showed that these 

thin garantiana and truellei beds expand eastward in the direction of Sherborne 

and pass laterally into thick yellow, blue-centred building stone (the 

Sherborne Building Stone) and rubbly limestone, best seen at Combe Limekiln, 

Clatcombe, and Redhole Lane, Sherborne. 

It follows that when the maximum thicknesses of all these zones are added 

together a very considerable amount of deposit is found to have been formed 

during a time often represented in any one section by quite insignificant beds. 

Buckman believed that the shifting of the belt of maximum sedimentation 

was not fortuitous, but was the direct result of the westward transgression of 

the sea. As the Vesulian Transgression advanced from the east or south-east 

the successive sedimentary belts, with their concomitant faunas, migrated 

westward. In this way the thin littoral facies of each zone, crowded with 

fossils, came to be overlain by the thick and poorly-fossiliferous facies of the 

next; and now the littoral facies proper to every zone is to be found to the 

west of the area of its maximum development. 

It is certain that a variable portion of the 'Top Beds' in the Sherborne 

district does not belong to the Upper Inferior Oolite at all but to the zigzag 

and fusca zones of the Fuller's Earth. This has become increasingly evident 

as a result of Richardson's revision of the district. In the white and grey 

argillaceous limestones with marl partings at King's Pit, Bradford Abbas, 

for instance, Richardson has obtained ammonite evidence that nearly the 

whole of the 'Top Beds' at that place (about 8 ft. in thickness) belong to the 

zigzag zone, the true Upper Inferior Oolite being represented below by seams 

only a few inches thick. 3 Of the same age he believes (but on this point there 

is less certainty) are the 30 ft. of thick limestones above the Truellei Bed at the 

Halfway House and in the area to the west, and he correlates them with 20 ft. 

of similar limestones above the Sherborne Building Stone and Rubbly Beds 

1 S. S. Buckman, 1893, Q.J.G.S., vol. xlix, pp. 479-522. 

2 L. Richardson, 1932, Proc. Cots. N.F.C., vol. xxiv, pp. 35-85. 

3 Idem, 1911, P.G.A., vol. xxii, p. 262.


of Crackment or Crackmore, south-west of Milborne Port. 1 The schloenbachi 

zone would seem on this hypothesis to be almost entirely absent. 

The most interesting deposit of all is that containing Strenoceras niortensis. 

It is known only at a few localities in the district, and excepting the basal conglomerate 

at Burton Bradstock and traces in the Hebrides, Strenoceras has 

been found nowhere else in the British Isles. In the Sherborne district the 

fauna has been recognized in 18 in. of ironshot oolite at Clatcombe, in a thin 

SU8-GARANTIANA OUTCROPS 

according ho Morley Davies' 

expianahon 

|— —j Sauzei Beds | | | | | j | Blagdeni Beds | |Nior|-ensis Beds 

0 1 1 3 - 4 s fc 7 9 9 1 0 mi 125 

FIG. 46. Maps showing diagrammatically the surface upon which the garantiana zone is 

supposed to have been deposited in the Sherborne district, on the supposition that the 

principal unconformity lies below th & garantiana zone (left), and on the alternative supposition 

that it lies below the niortensis zone (right). Continuous lines represent actual boundaries, 

broken lines hypothetical boundaries. (From A. M. Davies, 1930, P.G.A., vol. xii, p. 232, 

fig. 22.) 

brown ironshot at Frogden Quarry, Oborne, in the lower half of the Astarte 

obliqua Bed at the Halfway House, Compton, and in several other exposures 

in the immediate neighbourhood. 

Such a restricted distribution can be explained in two ways. Either the 

beds can be regarded as relict patches of a once continuous stratum which has 

been all but completely destroyed by denudation; or they can be visualized 

as the first deposits laid down by the invading sea at the beginning of or 

immediately prior to a transgression, soon to be overlapped by the more 

widespread deposits of the succeeding zones. On the interpretation chosen 

depends the position to which the niortensis zone should be assigned—whether 

to the top of the Middle Inferior Oolite or to the base of the Upper Inferior 

Oolite. The position here favoured, at the base of the Upper Inferior Oolite, 

has been recently advocated by Prof. Morley Davies (fig. 46). 2 

Prof. Davies points out that the extensive denudation required on the first 

hypothesis to reduce the niortensis zone of the whole of England to the two 

small patches near Sherborne must have taken a prolonged period of time, 

during which sediments would have continued to be laid down elsewhere on 

the deepest parts of the sea-bed. Such sediments would be intermediate in 

age between the niortensis zone and the overstepping or transgressive stratum, 

the garantiana zone. But no such sediments are anywhere found, although in 

France the niortensis and garantiana zones are seen over wide areas, always in 

1 L. Richardson, 1923, in 'Geol. Shaftesbury', Mem. Geol. Surv., p. 17. 

2 A. M. Davies, 1930, P.G.A., vol. xii, pp. 230-3.


contact. Further, the niortensis fauna as a whole is more closely allied to that 

of the garantiana zone than to that of the blagdeni zone below, and Prof. Davies 

considers it is too closely comparable to admit of any prolonged time interval 

having elapsed between the two hemerae. 

Consequently it would seem to be best to consider the niortensis zone as 

deposited in a greatly restricted sea during a period of regression, while the 

Bajocian uplifts and denudation were actually in progress; or, as Prof. Davies 

puts it, to 'regard the rare occurrence of the niortensis zone in England as 

marking the localities where sedimentation restarted prior to the great transgression 

in the garantiana hemera'. Such views are supported by the occurrence 

of the conglomerate of niortensis date at Burton Bradstock, and also by 

the position of the patches of beds near Sherborne, far down the dip slope in 

a re-entrant angle in the outcrop, where they would be likely to appear if they 

were overlapped rather than overstepped. 

In the Sherborne district and northward along the escarpment as far as 

Blackford 1 the thick limestones of garantiana and truellei dates, which 

transgress all the zones of the Middle and Lower Inferior Oolite over the 

North Devon Axis, form a homogeneous mass. Farther north, from Blackford 

to the Mendips, they can be more easily separated. 

In the southern part of the escarpment the most important feature is the 

garantiana zone, for by Blackford, Woolston and Hadspen the Sherborne 

Building Stone is continued in the form of the HADSPEN STONE. This is a 

massively-bedded, ferruginous, brown, building stone, with a maximum 

thickness of 10 ft., and is full of fossils, especially nests of Acanthothyris 

spinosa and S. sphceroidalis, together with lamellibranchs and echinoderms. 

The characteristic ammonite is Parkinsonia rarecostata S. Buck. Occasionally, 

as at Woolston, the base is seen to be conglomeratic, and everywhere over the 

axis it rests unconformably upon Upper Lias sands of Dumortierice or moorei 

date. 

Towards the northern part of the outcrop, near where the Lower and Middle 

Inferior Oolite appear in the Cole Syncline, and beyond the syncline towards 

the Mendips, the garantiana zone becomes recessive. No more is seen of the 

Hadspen Stone, and the zone consists of bands of ragstone or limestone 

separated by marl partings and often having bored upper surfaces. The 

thickness varies from a maximum of about 8 ft. to just over 3 ft. At Batcombe 

and Lamyatt Hill, north-west of Bruton, the base is again pebbly, and at 

Strutters Hill, near Cole, there is an Astarte obliqua Bed like that at the Halfway 

House, Compton, and in South Dorset. 

The truellei zone, where it comes to be separable from the garantiana zone 

north of Blackford, forms a second limestone, white, massive, sparry or flaggy, 

called the DOULTING STONE, from its great development around Doulting, 

close to the Mendips. At Blackford 9 ft. of the stone are seen, but the usual 

thickness in the exposures is 4 or 5 ft. It is generally massive below and 

flaggy towards the top, and is separated from the Hadspen Stone by a few 

layers of limestone and marl of uncertain age. 

In the northern part of the escarpment the Doulting Stone becomes the 

dominant surface rock, covering the whole outcrop from Bruton to beyond the 

Mendips. At Lamyatt Hill a rubbly limestone below the Doulting Stone, 

1 Hence based on L. Richardson, 1915, Q.J.G.S., vol. xxxvii, pp. 473-520.


yielding Parkinsonia densicosta (Quenst.), indicative of the truellei zone, 

abounds in corals (.Isastrcea), and Richardson considers that it can be identified 

as the most southerly indication of the Upper Coral Bed of Dundry Hill, 

Midford and the South Cotswolds. 

Close to the Mendips higher beds appear, representative of the schloenbachi 

zone, but these will be better considered later on. 

To summarize the salient features of the Dorset-Somerset area: the Upper 

Inferior Oolite is thickest in the centre, about Sherborne and Milborne Port, 

where the expansion occurs in the oldest zones, those of garantiana and 

truellei, and where also the niortensis zone is present. Here the thickest deposits 

are the least fossiliferous. The area of greatest thickness lies at the apex of 

a re-entrant angle in the outcrop, which exposes to view beds more southeasterly 

(farther down the dip slope) than can be seen at any other point, and 

therefore beds which may be presumed to have been formed under the deepest 

water. The thinning of progressively higher zones in a westerly direction, 

away from Sherborne, points to a transgression of the sea in that direction. 

It is interesting to note that an exposure on the most north-westerly projecting 

spur of the outcrop, at Hinton Park, north-west of Crewkerne, 1 shows 

a development of the Hadspen Stone, connecting the garantiana zone at that 

point and at Hadspen, on the outcrop north of Milborne Port. 

II. THE MENDIP AXIS 

Within some 5 miles of the Mendips, at Lamyatt Hill and Batcombe, the 

base of the garantiana zone, as has been remarked, becomes pebbly, and the 

Upper Lias sands on which it rests are older than the subjacent sands farther 

south, being here probably of dispansum date. On approaching close to the 

Mendips the garantiana zone passes entirely into a conglomerate and oversteps 

first on to attenuated representatives of various Liassic clays and later on to 

the Carboniferous Limestone. Eventually it disappears altogether, being 

overlapped by the truellei zone or Doulting Beds. 2 

As in previous periods, the Mendip Anticline did not function as a simple 

axis of elevation, but was flanked on the north by an area of minor disturbances 

extending beyond Radstock (map, p. 70). The conglomeratic facies 

of the garantiana zone, which is first met with on the south side of the hills at 

Doulting, laps round the eastern end, then strikes away to the north-west, 

where it is seen at Timsbury Sleight and on the outlier of Dundry Hill, in the 

form of the MAES KNOLL CONGLOMERATE (fig. 34, p. 196). 

In general the constituent pebbles and blocks in the conglomerate consist 

of yellow limestone and pale grey, fine-grained sandstone, much bored and 

rolled, with Serpulce attached, but near Mells-Road Railway Station there are 

pebbles of quartz and chert. 3 On Dundry Hill the conglomerate consists of 

lumps of blue-grey sandstone and irregularly-shaped masses of ironshot oolite 

(measuring up to 2 ft. 10 in. in diameter), together with rolled fragments of 

Pleydellia aalensis and Dumortieria. 4 

In a north-easterly direction, in a very short distance away from the 

1 L. Richardson, 1918, Q.J.G.S., vol. lxxiv, p. 161. 

2 L. Richardson, 1907, Q.J.G.S., vol. lxiii, pp. 383-426 for Bath-Doulting district. 

3 Ibid., p. 405. 

4 S. S. Buckman and E. Wilson, 1896, Q.J.G.S., vol. Iii, p. 685.


conglomerate belt, but evidently down a rapidly shelving shore, the garantiana 

zone passes into brown, finely ironshot, shelly ragstones and slightly sandy 

limestones, identifiable as the typical Upper Trigonia Grit of the Cotswolds. 

This facies is seen in a lane section at Wellow (where it is i ft. 8 in. thick), 

and in a road-cutting near Midford (where it is 5 ft. thick), and at both places 

the base is still somewhat pebbly. 1 

At Midford, Whatley Combe, and wherever the upper surface of the 

garantiana zone is seen, it is in turn bored and oyster-covered, and the 

truellei zone, represented by the Upper Coral Bed and Doulting Stone, rests 

non-sequentially upon it. The significance of this non-sequence will be seen 

in the next section. 

The Doulting Stone increases greatly in thickness as it approaches the 

south side of the Mendips, reaching a maximum of 44 ft. in the railway-cutting 

and adjoining quarries at Doulting. It consists of a brownish, oolitic, usually 

massively bedded limestone, and 16 ft. of the upper part are an excellent 

false-bedded freestone. The Doulting Freestone is said to be more durable 

than the Bath Stone, a view borne out by Wells Cathedral and Glastonbury 

Abbey, which were mainly built of it. 

On approaching the Palaeozoic core of the eastern end of the Mendip Hills, 

the Doulting Stone, after overlapping the thin garantiana conglomerate, 

passes on with little change over the planed and eroded surface of the Carboniferous 

Limestone (PL XI). Still from 20 to 30 ft. in thickness, h forms a 

covering which would hide the Palaeozoics beneath but for the fact that the 

plateau is deeply dissected by valleys, along the sides of which the junction is 

exposed to view in numerous quarries (map, p. 70). 

The extraordinary geological interest of the area about Vallis Vale, near 

Frome, has perhaps never been better expressed than by W. D. Conybeare in 

1822, in the following passage quoted by Richardson in his well-known paper 

on the Inferior Oolite of the Bath-Doulting District, the source of the facts 

on which the present account is based. 2 In the words of Conybeare, 

'an uniform and elevated plain of the Inferior Oolite spreads over the whole surface, 

furrowed by valleys about 150 or 200 ft. deep, which expose the Mountain Limestone. 

The character of many of these valleys (particularly of that between Mells and 

Frome and its lateral branches) is highly romantic; the streamlets that flow through 

them being skirted by bold and rocky banks overgrown by feathering woods; while 

the geologist observes, as a feature of peculiar interest in their precipitous escarpment, 

the actual contact of the horizonal bed of Inferior Oolite resting on the truncated 

edges of strata of Mountain Limestone, thrown up in an angle of from 50 to 

60 degrees. This line of contact is sometimes perfectly level for a considerable distance 

(as if the edges if the Mountain Limestone strata had been rendered smooth 

by some mechanical force abrading them previously to the deposition of the Inferior 

Oolite), but in other instances it is rugged and irregular; sometimes the contact is 

marked by a breccia of fragments of the older, cemented by the newer rock, but 

this is by no means constant.' 

In places, in addition, a thin remanie bed representing various zones of the 

Liassic and Rhaetic rocks is interposed, but in most of the area about Vallis 


2 W. D. Conybeare and W. Phillips, 1822, Outlines of the Geology of England and Wales, 

pt. i, pp. 254-5.


Upper Inferior Oolite (Doulting Beds) overlying Carboniferous 

Limestone, Nunney, Eastern Mendips. 

Photo. 

The overhanging ledges in the Carboniferous Limestone are pre-Jurassic 

thrust-planes. 

Upper Inferior Oolite (Doulting Beds) overlying Carboniferous 

Limestone, Vallis Vale, near Great Elm, Eastern Mendips. 

PLATE XII


Vale the truellei zone rests directly upon the Carboniferous Limestone. As 

described by Richardson: 1 

'The surface of the Carboniferous Limestone is remarkably even. If one stands 

upon the platform formed by this rock after the Inferior Oolite has been stripped off 

by the quarrymen, and looks across the flat-bottomed valley, with its mural sides, 

at the other extensive quarries, one cannot repress a feeling of astonishment at the 

excessive evenness of the plane of erosion. This surface is riddled with annelid— 

and, less commonly, Lithopliaga—borings, and in places is strewn with oysters.' 

The truellei zone is the only zone in the whole series of the Jurassic Rocks 

that can be seen passing in more or less unaltered form directly across the 

Palaeozoic core of one of the periclines of the Mendip Axis. This fact testifies 

to the great extent of the subsidence and transgression which preceded its 

formation. The same, too, is witnessed by the thickening of the Doulting 

Stone in the immediate vicinity of, and over, the axis. Whether the truellei 

zone in turn thinned out and passed into a conglomerate higher up against 

the Mendip Hills before the core was stripped bare by Tertiary and Quaternary 

erosion, or whether the Doulting Beds formerly passed right over the 

summit, showing that it was entirely submerged, is a difficult question to 

answer. At Cranmore, however, the surface indications are strongly favourable 

to the view that the Doulting Beds ended abruptly against a cliff, or at least 

a sharply rising slope, of the Carboniferous Limestone; moreover, about 

Whatley the Upper Inferior Oolite is entirely overstepped by the middle part 

of the Fuller's Earth. 

The Upper Inferior Oolite is completed in the neighbourhood of Doulting, 

Frome and northward by a development of the schloenbachi zone, in places 

up to 10 ft. thick. But the facies of this zone belongs to the South Cotswold 

province, of which it is essentially a continuation, and with which it is better 

treated. At the top a thin white earthy limestone (1 ft. 2 in.), exposed in 

Doulting Bridge Quarry and the railway cutting, abounds in ammonites of the 

zigzag zone, and this is succeeded by Fuller's Earth just as in South Dorset. 

III. THE COTSWOLD HILLS 2 

There are plentiful signs of the great upheavals and erosion connected with 

the Bajocian Denudation in the Cotswold basin of deposition. Although the 

signs are less spectacular than those just described over the Mendip Axis, 

the detailed work of S. S. Buckman showed conclusively that they are present, 

and of no small magnitude. Their measure may be judged by an examination 

of the strata upon which the garantiana zone reposes between the Mendips 

and the Vale of Moreton (fig. 35, facing p. 197). 

The blagdeni and niortensis zones, which should normally precede the 

garantiana zone, have been removed from the whole region, or were never 

deposited. The sauzei zone, next below, is confined to a small area in the 

centre of the deepest syncline, at the summit of the Cleeve Hill plateau. The 

rest of the eight zones of the Middle and Lower Inferior Oolite are in turn 

overstepped away from Cleeve Hill, until along the western margin of the 

Vale of Moreton in the north and between Old Sodbury and the Mendips 

in the south, garantiana beds come to rest directly upon Upper Lias. 


2 The sources are the same as in the corresponding section of Chapter VIII, p. 197.


The overstep is not so simple as this plain statement would indicate, 

however, for, as has been explained in previous chapters, the Lower and Middle 

Inferior Oolite deposits were thrown into two smaller synclines and an anticline 

within the main Cotswold Basin. The Birdlip Axis passed NW.-SE. 

under Birdlip, running approximately along Ermine Street towards Cirencester. 

Over the crest of this axis in the region of the outcrop the overriding 

garantiana zone was laid down upon an eroded, bored and oyster-covered 

surface of the Upper Freestone, and pebbles of Upper Freestone are included 

in its basal layers. In the Cleeve Hill syncline to the north, as we have seen, 

beds as high as the sauzei zone were preserved. To the south of the Birdlip 

Anticline a smaller syncline was formed about Painswick, but as the greater 

part of this has been destroyed by the retreat of the escarpment, the highest 

beds remaining beneath the garantiana zone are not so high in the sequence 

as those preserved upon the projecting plateau of Cleeve Hill (fig. 36, p. 199). 1 

In spite of the enormous amount of disturbance that attended the Bajocian 

Denudation, the conditions prevailing before it and governing deposition in 

the Cotswold province continued with surprisingly little alteration after it. 

The beds comprising the Upper Inferior Oolite are essentially similar in 

general facies, both lithologically and palaeontologically, to those building the 

Middle and Lower divisions. This may be taken as a further indication that 

the bulk of the disturbances were orogenic rather than epeirogenic. 

As before, corals grew along the coast of the Welsh land, where the waves 

broke fragments off the reefs and spread the debris over the sea-bed to the 

east. The same types of detrital accumulations grew up, composed of the 

hard parts of echinoderms, corals, brachiopods, sponges, lamellibranchs and 

gastropods, with occasional seams of marl and banks of false-bedded oolite. 

As in the earlier divisions, the largest numbers of recognizable corals are 

found in the west, along the escarpment of the South Cotswolds from Stroud 

southward. Here in the murchisonce hemera two beds of corals accumulated, 

the nearest approach to the remains of a coral reef preserved anywhere in the 

Cotswold Inferior Oolite; the lowest bed, between the Lower Freestone and 

the Pea Grit, is from 15 to 25 ft. thick on the sides of the Slad Valley near 

Stroud, and consists of large masses of coral and coralline limestone embedded 

in a creamy mudstone, together with a considerable number of sponges. In 

the same area a similar coral bed, known as the Upper Coral Bed, forms part 

of the truellei zone in the Upper Inferior Oolite. All the genera of the corals 

are the same, and the general facies is identical. Comparing the corals of the 

later reefs with the earlier, Martin Duncan wrote: 2 

'The remarkable varieties of Thecosmilia gregaria, which resemble the genus 

Symphyllia and Heterogyra, are found principally in the lower reef, but they exist 

in the upper also. Some species appear to be peculiar to the different reefs, but . . . 

there is evidently a considerable affinity between the [coral] faunas of the reefs, and 

there is nothing to indicate anything more than a temporary absence from and a 

return of the species to an area.' 

Important changes in the configuration of the coast-line and the relative 

1 The uprise of the lower beds in the south-west limb of the Painswick Syncline, far down 

the dip-slope beneath the Great Oolite, was proved in a boring at Shipton Moyne, where the 

garantiana zone was found to rest upon the Pea Grit. See L. Richardson, 1930, 'Wells and 

Springs of Gloucestershire', Mem. Geol. Surv., p. 150. 

2 M . Duncan, 1872, 'Supplementary Monograph of the Brit, Foss. Corals', Pal. Soc., p. 11.


depths of the various minor areas of deposition must, nevertheless, have taken 

place as the result of the Bajocian Denudation and the earth-movements which 

gave rise to it. 

The importance of the ancient Mendip Axis was greatly diminished, the 

provinces to north and south of it coming to be much less sharply differentiated. 

In Upper Inferior Oolite times the Cotswold type of deposit was accumulated, 

not only on Dundry Hill, but also across the eastern end of the axis, and 

through eastern Somerset far down towards the Dorset border. In truellei 

times, as already remarked, rolled corals reached as far south as Lamyatt 

Hill, near Bruton. 

Thus the two areas came to be blended, and by zigzag and fusca times 

(basal Fuller's Earth) autochthonous ammonites were to be found from 

Normandy at least as far as the South Cotswolds. 

SUMMARY OF THE UPPER INFERIOR OOLITE OF THE COTSWOLDS (INCLUDING 

BATH AND DUNDRY) 

The fullest and most varied series of deposits is found in the South Cotswolds, 

in the Bath district, and on the Dundry outlier. To the north-east, 

away from the source of the sediment, some of the subdivisions mingle and 

lose their identity, while others thin entirely away (see fig. 35, p. 197). 

Schloenbachi and Upper Truellei Zones. 

RUBBLY BEDS and ANABACIA LIMESTONES. The schloenbachi zone is represented 

in the South Cotswolds, the Bath district and on Dundry Hill by from 

6 to 12 ft. of white oolitic limestone. The upper or Rubbly Beds are usually 

little more than a rubbly development of the top, but locally, as on Stinchcombe 

Hill, they merit consideration as a distinct lithic division. Here there 

is a remarkable bed crowded with Microzoa, closely comparable with that on 

the Dorset Coast, especially at Shipton Gorge. The remainder, or Anabacia 

Limestones, consists of evenly-grained white oolite, often flaggy, and characterized 

by an abundance of the little button-coral, Anabacia complanata (Defr.). 

The Anabacia Limestones present constant features in the district from 

Doulting to Dundry Hill and onward to Old Sodbury, ten miles north of Bath. 

Beyond this, at Horton, they become temporarily softer and more oolitic, but 

at Scar Hill, Nailsworth, their original form is resumed for a short distance. 

The DOULTING STONE becomes thin north of the Mendips. At Midford it 

is only some 12 ft. thick, and about the same thickness is maintained into the 

South Cotswolds, the essential characteristics of the stone being nevertheless 

preserved almost as far as Stroud. 

CLYPEUS GRIT. In the Stroud district the Doulting Stone, Anabacia Limestones 

and Rubbly Beds lose their distinctive features and fuse laterally to 

form a different deposit, the Clypeus Grit. 1 

The Clypeus Grit has the widest extension in the Cotswolds of any bed in 

the Inferior Oolite. The upper third is uniformly rubbly and is crowded 

with fossils, of which the most conspicuous are the large Clypeus plotii and 

Stiphrothyrids of the various species known collectively as Terebratula 

globata. In the Cheltenham district Anabacia complanata abounds, recalling 

1 The upper portion of this includes the so-called White Oolite of Edwin Witchell (Geology 

of Stroud, p. 62), which is not of zigzag-fusca date as supposed by Buckman (teste L. Richardson, 

in lit.)-


the Anabacia Limestones on the same horizon farther south. The lower twothirds 

are a more massive limestone from which fossils do not weather so 

easily. Lithologically the distinguishing feature of both divisions is the 

invariable presence of large ooliths or pisoliths. 

The full thickness of the Clypeus Grit is rarely seen, owing to its forming 

the capping to most of the exposures. It was, however, completely sectioned 

in the region of its maximum thickness in the North Cotswolds by the railway 

west of Notgrove Railway Station, where the thickness is 40 ft. 6 in. One of 

the finest complete sections is in a quarry at Rodborough Hill, Stroud, where 

part of the rock resembles a pudding-stone from the abundance of brachiopods 

(mainly Stiphrothyrids). 

Lower Truellei and Upper Garantiana Zones. 

UPPER CORAL BED and DUNDRY FREESTONE. The non-sequence below the 

Doulting Stone in the Mendip region, denoted by an eroded and oystercovered 

surface of the garantiana beds, disappears north of the axis, where 

two strata, the Upper Coral Bed and the Dundry Freestone, take its place. 

These beds are believed to complete the lower part of the truellei zone and 

the upper part of the garantiana zone. 

The UPPER CORAL BED is a useful stratum owing to its persistent characters 

and widespread distribution. It is crowded with Isastraean corals, and in addition 

contains a rich fauna of micromorphic brachiopods 1 (at least 17 species, 

of which the commonest and most characteristic is Spiriferina? oolitica), ostracods 

(11 species), foraminifera (16 species) and a few remains of sponges, 

polyzoa, echinoids, and holothurians. It is therefore a typical debris derived 

from the destruction of growing coral reefs. The bed is traceable from 

Lamyatt Hill near Bruton by way of Dundry Hill and the Bath district into 

the South Cotswolds as far north as Rodborough Hill and Stroud. Beyond 

this it dies away, but it may be represented by sporadic occurrences of corals 

as far as Hook Norton, in Oxfordshire. 

The age of the Upper Coral Bed was determined by the finding of a specimen 

of Lissoceras psilodiscum (Schlcenbach) at Coombe Hill Quarry, near 

Wotton under Edge. 2 

The interest of the bed lies in the proof that it affords of the survival or 

revival of coral growth along an extended length of coast-line after the disturbances 

connected with the Bajocian Denudation. 

The DUNDRY FREESTONE 3 is much less widely distributed than the Upper 

Coral Bed, being restricted in anything like its maximum thickness to the 

west end of Dundry Hill (near the church), where it is 27 ft. thick. At the 

eastern end it has dwindled to 4 ft. (in the quarry near the Butcher's Arms), 

and to 3 ft. 4 in. in another quarry east of the road to the southern edge of the 

hill. It is continued in the outlier of Timsbury Sleight, where it is 4 ft. 3 in. 

thick, and on the main outcrop it extends from near the village of English 

Combe in ever-diminishing thickness into the South Cotswolds as far as 

Stroud, where Richardson believes it to be identifiable as a thin limestone band 

4 in. thick in Stanley Wood Quarry, and 2 in. thick at Wotton under Edge. 4 

1 For a list of microzoa from Timsbury Sleight and neighbourhood see C. Upton, in 

Richardson, 1907, Q.J.G.Svol. lxiii, p. 413. 

2 L. Richardson, 1910, Proc. Cots. N.F.C., vol. xvii, p. 86. 

3 S.S. Buckman and E.Wilson, 1896,10c. cit. 4 L.Richardson, 1910, loc. cit., pp. 121, 104.


As its name implies, the Dundry Freestone is a good building stone, and it 

has been much used locally. Like other rapidly-accumulated deposits, it has 

yielded little or no palaeontological information. 

North of the Stroud district, over the rest of the Cotswolds, the Dundry 

Freestone and Upper Coral Bed are overlapped, and the Clypeus Grit usually 

rests non-sequentially upon the lower part of the garantiana zone—the Upper 

Trigonia Grit. 

Lower Garantiana Zone. 

UPPER TRIGONIA GRIT. The least variable and most persistent member of 

the Upper Inferior Oolite, the only zone to extend without appreciable change 

from the Mendips near Midford and Wellow across the entire Cotswold Basin 

to the flank of the Vale of Moreton Axis, is the Upper Trigonia Grit (see 

fig- 35> P- 197)- 

It attains no great thickness, the maximum measurement even in the North 

Cotswolds being 9 ft., while 6-8 ft. is the average. The 'grit' (a misnomer) 

is a hard, grey, rough-textured limestone, often somewhat flaggy, and full of 

fossils. The difficulty of extracting the fossils contrasts markedly with the 

ease with which perfect specimens may be obtained from the overlying 

Clypeus Grit. The typical species are Trigonia costata Sow., which often 

occurs as casts in great profusion, and the Scaphoid species, Trigonia duplicata 

Sow. Equally characteristic are Acanthothyris spinosa and various forms of 

Stiphrothyris. 

The unconformable relations of the Upper Trigonia Grit to the underlying 

Middle and Lower Inferior Oolite and earlier beds have already been 

described. 


The Vesulian transgresses on to Upper Lias across the Vale of Moreton 

Axis, just as over the other axes that took part in the revived orogenic activity 

at the end of Middle Inferior Oolite times. Over the Mendip Axis it is the 

Doulting Beds that overstep the older formations without themselves undergoing 

any great change; here it is the same two zones, those of truellei and 

schloenbachi, in the form of the Clypeus Grit. Over both axes the garantiana 

zone is overlapped. 

The UPPER TRIGONIA GRIT thins rapidly towards the eastern margin of the 

North Cotswold hill-mass and is absent over approximately the same marginal 

strip of country, overlooking the Vale of Moreton, as that in which the Oolite 

Marl is wanting (fig. 38, p. 207). It is last seen in the railway-cuttings west of 

Bourton on the Water, where its thickness is a little over 3 ft. In the last 

cutting eastward (Aston Farm Cutting) it has disappeared and Clypeus Grit 

has overlapped on to Notgrove Freestone. 1 No positive indication of the 

garantiana zone is known between this point and the Hebrides. 

The CLYPEUS GRIT passes on, changing little in its lithology or in its organic 

contents, but gradually becoming thinner. On the eastern plateau about 

Chipping Norton and in the Iccomb hill-mass it is still about 20 ft. thick, and 

it rests upon the Whitbian portion of the Upper Lias clay everywhere south 

of the boundary of the Scissum Beds, as shown in fig. 38. The thickness is 

never made up again east of the Vale of Moreton Axis, and in the Evenlode 

1 L. Richardson, 1929, 'Geol. Moreton in Marsh', Mem. Geol. Surv., p. 80.


Valley and about Chipping Norton there is a further slight diminution as 

compared with the Vale of Bourton. The rock is still readily recognized by 

its large ooliths and pisoliths and its perfect fossils, especially of Clypeus 

plotii and Stiphrothyrids, while the quarries show that the upper 8 ft. are still 

rubbly and the lower 12 ft. more massive, as in the Cotswolds. 1 

The last exposures where the Clypeus Grit is well displayed are the old 

Marlstone workings at Fawler, near Charlbury, in the Evenlode Valley. Here, 

to the last, it is quite typical, with its upper portion rubbly and its lower 

portion more massive, and it has yielded many fine Clypei and other fossils to 

several generations of collectors. Resting directly on it is the Chipping Norton 

Limestone, of zigzag-fusca date, while welded to its under side is a hard band, 

a few inches thick, containing corals—possibly a representative of the Upper 

Coral Bed of the Cotswolds. Below the coral bed has been seen a still thinner 

seam of conglomeratic sandstone with rolled pebbles of limestone, resting on 

a bored and eroded surface of a thin argillaceous limestone band, which is 

presumably the top of the Upper Lias. 2 

Towards the south the Clypeus Grit can be traced along the Evenlode Valley 

as far as Stonesfield, where it is lost beneath the younger rocks. 

Towards the north and east it dies out with surprising rapidity. The Hook 

Norton railway-cutting displays a section on almost exactly the same line of 

longitude as Fawler but 9 miles farther north, and here the Clypeus Grit as 

such has entirely disappeared. All that is left between the Hook Norton 

Beds (lower part of the Chipping Norton Limestone) and the Scissum Beds 

is about 20 in. of hard, ferruginous limestone, in which are embedded an 

irregular, loose, conglomeratic band and locally an impersistent band of corals. 

Contrary to what is seen at Fawler, however, the pebbles lie above the band 

of corals. The pebbles are of limestone and broken shells, rolled, bored, 

encrusted with Serpulce and oysters, and enclosed in a brown marl. 3 From 

the coral bed, which also suggests itself as a possible representative of the 

Upper Coral Bed of the South Cotswolds, Tomes recorded Isastrcea limitata, 

Thamnastrcea defrancei (Mich.), Clausastrcea conybeari (Ed. and H.), Latimeandra 

lotharinga (Mich.) and other species. 4 

A similar conglomeratic band of the same thickness, but without corals, 

has been described at Fern Hill, near Bloxham. s This is the most easterly 

known occurrence in this part of the country of any rock that can be ascribed 

to the Upper Inferior Oolite. The formation dies out completely before 

reaching the Cherwell Valley, being overlapped by the equivalents of the 

Chipping Norton Limestone, as it so nearly is at King's Pit, Bradford Abbas. 

1 L. Richardson, 1907, Q.J.G.S., vol. lxiii, p. 441. 

2 My principal authority for the Fawler section is L. Richardson, 1910, Proc. Cots. N.F.C., 

vol. xvii, p. 31, and for the description (but not the interpretation) of the beds at the junction of 

the Clypeus Grit and Upper Lias C. J. Bayzand, in Professor Sollas's 'Geology of the Country 

Around Oxford* in The Natural History of the Oxford District, 1926, p. 34, fig. 1. Mr. Bayzand 

appears to have been misled by the more massive nature of the lower part of the Clypeus Grit 

into calling it Upper Trigonia Grit; it is quite typical Clypeus Grit, however, and there seems 

no reason for departing from Mr. Richardson's interpretation of sixteen years earlier. Similarly 

there seems no evidence for identifying the pebbly seam as 'Gryphite Grit', or the bored 

limestone as 'Scissum Bed'; the presence of either would be contrary to all expectations. 

Richardson compares the conglomeratic bed with the garantiana conglomerate of the Radstock 

district and Maes Knoll, Dundry. 

3 L. Richardson, 1911, Proc. Cots. N.F.C., vol. xvii, p. 214. 

4 R. F. Tomes, 1879, P.G.A., vol. vi, pp. 152-65. 

5 L. Richardson, 1922, Proc. Cots. N.F.C., vol. xxi, p. 131.


The overlap of the Upper Inferior Oolite 

clearly has no connexion with the Vale of 

Moreton Axis, but is much more widespread, 

of the class of phenomena resulting from epeirogenic 

movements. It is, in fact, part of a 

general overlap against a rising coast-line to 

eastward (fig. 47). The overlap that is begun 

by the Upper Inferior Oolite is continued 

by the equivalents of the Chipping Norton 

Limestone (as will be seen in the next chapter) 

and then in turn by several other members 

of the Great Oolite Series. 

V. LINCOLNSHIRE AND YORKSHIRE 1 

The uppermost shelly beds of the Lincolnshire 

Limestone at Weldon and Ponton yield 

a fauna of rolled and principally micromorphic 

gastropods, which, as W. H. Hudleston 

pointed out, show marked differences from 

those in the lower beds and to some extent 

even display Bathonian affinities. It is possible 

that these highest beds of the Lincolnshire 

Limestone represent part of the Upper Inferior 

Oolite, but their age must remain open 

until the stratigraphy of the Lincolnshire 

Limestone has been investigated in detail. 

In Yorkshire the uppermost or predominantly 

argillaceous division of the Scarborough 

Beds (above the Scarborough Grey 

Limestone with ammonites of blagdeni date) 

abounds in Pseudomonotis lycetti Rollier, with 

which is associated Trigonia signata Lyc. 

These are the two most characteristic fossils 

of the Hook Norton Beds in North Oxfordshire, 

and so a provisional correlation of these 

beds with the Hook Norton Beds or zigzag 

zone may be tentatively suggested. Such a 

correlation implies the absence or thin and 

disguised representation of any Upper Inferior 

Oolite. 

Both of these correlations are attended with 

such uncertainty that the rocks have been ^ \ Q g.g 

described in Chapter VIII with the Lower 

and Middle Inferior Oolite, of which they 

are usually considered to form a part. 

VI. THE HEBRIDEAN AREA 

In the islands of Raasay and Skye the thick 

Inferior Oolite sandstones, of which the 

1 For references to the Lincolnshire and Yorkshire 

areas see preceding chapter. 

s


highest several hundred feet belong to the blagdeni zone, are abruptly overlain 

by up to 10 ft. of plastic clay and shale, yielding ammonites of the garantiana 

and possibly also of the niortensis zones. The outcrop of the clay, following 

so suddenly upon the thick sandstones, is easily traceable in both islands. 

In Skye the shales are indifferently exposed in a number of places along the 

heathery slopes of Strathaird, where the black ammonite-bearing shales pass 

up into dark-grey shaly, micaceous flags, the whole about 30 ft. thick. There 

is a gradual change upward through the flags into the grey and white, pebbly 

sandstone of the Great Estuarine Series (see Chapter X). Specimens of 

Garantiana have been found both in Strathaird and in Trotternish, north of 

Bearreraig, where the plastic clay passes laterally into soft black sandstone. 1 

The most fossiliferous locality yet discovered is the bank of a stream 

north-east of Storav's Grave, in Raasay, the only satisfactory exposure in that 

island. 2 The Survey collected Garantiana cf. garantiana and four other forms, 

and in addition Strenoceras bifurcatum (Ziet.), S. minimum Wetzel, and S. 

subfurcatum (Schloth.). Especial interest attaches to this discovery in view of 

Prof. Davies's suggestion, adopted above, to consider the niortensis zone as 

the lowest zone of the transgressive Vesulian. The idea is strongly supported 

by this occurrence, in so remote a locality, of Strenoceras and Garantiana in 

close association in a bed differing completely from the underlying blagdeni 

and lower zones. Evidently the Vesulian Transgression is marked here by an 

abrupt change of lithology, and the important point is that Strenoceras 

entered after the change of conditions (which was apparently one to deeper 

w r ater). 

It is strange that in the south of the Hebridean area no sudden alteration in 

the type of sedimentation appears to have taken place with the Vesulian 

Transgression, for at Port nam Marbh, in SE. Mull, 3 Garantiance have been 

found 10 ft. below the top of the Inferior Oolite sandstone. Both in Mull and 

in Ardnamurchan the sandstone continues right up to the base of the Great 

Estuarine Series (which is considered to be of Great Oolite age). No evidence 

for the presence of any higher ammonite zones than that of garantiana has 

been found anywhere in Scotland, where estuarine or deltaic conditions prevailed 

until the time of the Cornbrash. 

VII. KENT 4 

In some of the borings in Kent sands and sandy limestones were found to 

rest upon the Lias and to overstep it northward on to the Palaeozoic platform. 

These sandy strata are not all of the same age; at Tilmanstone and Snowdown 

Collieries they yielded fossils typical of the lower part of the Great 

Oolite, but at Brabourne and Dover they proved to belong to the Upper 

Inferior Oolite. 

Most information was obtained at Dover, where a shelly sand, with hard 

bands of calcareous grit, and containing numerous small pebbles and phosphatic 

nodules, was proved resting on the falcifer zone of the Upper Lias. 

Some twenty-five species of lamellibranchs were obtained and these agree as 

1 C. B. Wedd, 1910, 'Geol. Glenelg, Lochalsh and SE. Skye\ Mem. Geol. Surv., p. 116. 

2 G. W. Lee, 1920, 'Mes. Rocks Applecross, Raasay and NE. Skye', Mem. Geol. Surv., 

pp. 47, 50-1. 

3 G. W. Lee, 1925, 'Pre-Tert. Geol. Mull, Loch Aline and Oban', Mem. Geol. Surv., p. 99. 

4 Based on Lamplugh, Kitchin and Pringle, 1923, loc. cit.

UPPER INFERIOR OOLITE: KENT 247 

a whole with the fauna of the Upper Inferior Oolite. The most abundant 

were Trigonia of the group of T. duplicata Sow., a species common in the 

Upper Trigonia Grit (garantiana zone) of the Cotswolds, and also such typical 

shells as Pholadomya fidicula Sow. and Gresslya abducta (Phil.). 

Messrs. Lamplugh, Kitchin, and Pringle wrote: 1 

'The. condition of the fossils in the sand-bed at Dover suggests that the sea-floor on 

which they lay was scoured by sand-laden currents, as many of the shells show 

signs of considerable abrasion by which most of their ornament has been obliterated 

... in an example of a costate Trigonia all the costas have been worn away on the 

anterior part of the shell, while they are unworn posteriorly.' 

The unconformable relations of these sandy beds to the Lias, without the 

intervention of any Lower or Middle Inferior Oolite strata, is in harmony 

with the palaeontological evidence in pointing to their having been laid down 

during or after the Vesulian Transgression. Their being overlapped northward 

by the lower part of the Great Oolite Series, of which the higher portion 

in turn overlaps the lower and passes on to the Palaeozoic platform, lends 

strong support to this correlation, for it is an additional point of agreement 

with Oxfordshire and Northamptonshire. 

1 Ibid., p. 22.

CHAPTER X 

GREAT OOLITE SERIES 

Ammonite Zones. 1 Brachiopod Zones. Cotswold Strata. 2 Dorset Strata. 

? 

| Epithyris marmorea Wychwood Beds 

Epithyris bathonica 

and Ornithella 

digona 

Bradford Beds 

Forest 

Marble 

Kemble Beds (Gap of 

White Limestone 

Uncertain 

Extent) 

Tulites 

subcontractus 

and 

Morrisiceras 

Epithyris oxonica 

Hampen Marly Beds 

Taynton Stone 

Stonesfield Slate 

Upper 

Fuller's 

Earth 

morrisi 3 

Oppelia fusca 

Zigzagiceras 

zigzag 

Ornithella bathonica, 

O.pupa and Stiphrothyris 

globata 

p 

Upper Fuller's Earth 

Fuller's Earth Rock 

Lower Fuller's Earth Lower Fuller's 

Earth 

Chipping Norton Crackment 

Limestone 

Limestone 

THE Great Oolite Series, less the Cornbrash, is here described as a single 

formation in the same sense as in all the memoirs of the Geological 

Survey. It includes the Fuller's Earth and Zigzag Beds (which latter probably 

pass laterally into the lower part of the Chipping Norton Limestone), the 

Fuller's Earth Rock, and the Great Oolite Limestones with their numerous 

successive variants of facies—the White Limestone, Forest Marble, Bradford 

Clay, Hinton Sands, Bath and Taynton Freestones, Hampen Marly Beds, 

Upper Estuarine Series, Stonesfield Slate Beds, &c. These constitute a 

bewildering but palaeontologically interesting complex of strata, of a thickness 

and importance out of all proportion to the thin and relatively straightforward 

Upper Inferior Oolite, upon which they follow with perfect conformity. The 

lower half (up to the Stonesfield Slate Beds) of the Great Oolite Series, as here 

1 Previous writers have sometimes proposed more ammonite zones: the reasons for 

the selection here made are discussed in the text. One or two ammonites have been found 

in the Bradford and Kemble Beds, but it would be absurd to use them as zonal indices 

(Pi. XXXV). 

2 Each of these stratal divisions (with 2 exceptions) represents a well-characterized faunizone, 

recognizable by an assemblage of mollusca and brachiopoda. (The exceptions are the 

Fuller's Earth clays, which are largely unfossiliferous). The significance of this has been discussed 

in Chapter I, pp. 34-5. 

3 Morrisites (Buckman, 1921) is considered by Dr. Spath to be a synonym of Morrisiceras 

(Buckman, 1920), and the genus is assigned to the Macrocephalitidae, not the Tulitidae as 

was done by Buckman. See 1932, Med. om Grenland, vol. LXXXVII, no. 7, pp. io, 15.

GREAT OOLITE SERIES 249 

understood, forms the upper part of the Vesulian Stage of Marcou, overlapping 

with d'Orbigny's Bathonian. 

The different facies of the formation have been known since the earliest 

times, as is shown by their names, most of which date from William Smith 

and Buckland; but it is only in the last few years that any real progress has 

been made in elucidating the true correlation. There are still many points 

that remain undecided and some are likely to remain so for many years to 

come, for the difficulties appear insurmountable. They arise from the peculiar 

changeability of both the fauna and the lithology and the absence or extreme 

rarity of ammonites throughout the greater part of the succession. In these 

respects the Great Oolite Series is analogous with the Corallian Beds, in 

which also ammonites are abundant in certain thin beds but entirely absent 

or extremely rare through great thicknesses of rock, while facies-faunas introduce 

complications at all horizons. Neither formation can be described on a 

strictly palaeontological basis in the same way as the Inferior Oolite or Lias. 

We cannot draw up a sequence of zones and, having described their development 

on the South Coast, proceed to trace them inland across the country, 

following out their changes of facies. Assemblages that remain constant over 

such wide areas are too scarce and there are too few trustworthy index-species. 

We cannot even define a succession of partly palaeontological and partly 

lithological divisions that we can be sure of recognizing along more than a 

small fraction of the outcrop. This is possible in the Corallian Beds and the 

task is proportionately easier. Instead w Te are reduced, in dealing with the 

Great Oolite Series, to describing the succession in each district on its own 

merits, endeavouring as we go along to draw comparisons and establish 

correlations, but usually without sufficient certainty to justify any simplification 

of the stratigraphical nomenclature. 

At the base of the formation the zones of Zigzagiceras zigzag and Oppelia 

fusca provide a convenient datum, for in them, at least in the south, ammonites 

usually abound; but the upward limit of the fusca zone is vague. Another 

horizon yielding ammonites in fair abundance is the Fuller's Earth Rock of 

Dorset, but farther north specimens are too rare to be of much service. They 

belong to laevigate and simplified types, some of which seem to have a very 

long range: as mentioned in Chapter I, their biozones seem to exceed several 

faunizones in thickness. Brachiopods often abound and they are usually the 

best guides in correlation. Nevertheless, when a wide area is considered their 

colonial habits become a serious drawback, and it is often necessary to fall 

back upon a comparison of the general assemblage of lamellibranchs and 

gastropods. In local correlations in Oxfordshire certain gastropods of the 

family Nerineidae have been found extremely useful, the epiboles of four 

species maintaining a constant relation over a considerable tract of country 

where other fossils fail. Oysters also are often valuable. 

The master problem in the stratigraphy of the Great Oolite Series is the 

complete disappearance of the Great Oolite limestones, excepting the Forest 

Marble, south of the region between Bath and the Mendip Axis. The extent 

to which any of the Upper Fuller's Earth south of this is equivalent to any of 

the limestones to the north is still an open question, but such evidence as there 

is will be reviewed in this chapter.

i9o 

LOWER OOLITES 



The Great Oolite Series on the coast is predominantly a clay formation. It 

comprises the following divisions: 

[Cornbrash above.] ft. 

Forest Marble . . . . . 80-90 

Goniorhynchia boueti Bed . . . 1 

Upper Fuller's Earth Clay. . . ?i25 

Fuller's Earth Rock . . . . 2 5 

Lower Fuller's Earth Clay. . . ?i40 

The Scroff with Oppelia fusca . . J 

Zigzag Bed . . . . • £ 

[schloenbachi limestone below.] 

Total about . . 380 

The best section is the very fine one in Watton Cliff (Plate XII) between 

West Bay (Bridport Harbour) and Eypesmouth, where the formation is let 

down in a great trough fault between Middle Lias on the west and Bridport 

Sands on the east. The Forest Marble forms the capping to the cliff 1 and the 

projecting crags of the highest 80-90 ft. Next comes the Boueti Bed, which, 

with a parallel band of white cementstone at the top of the Fuller's Earth, are 

easily recognized datum lines, about 100 ft. above the beach. Below, an almost 

perfectly vertical face of nearly homogeneous conchoidal grey clay extends to 

the foot of the cliff. 

Watton Cliff is unscaleable from above or below, but at the west end there 

is a deep recess, known in geological literature as the Fault Corner, where 

a path leads up to the top. The path is only made possible by the melting 

down of the clays in a tumbled mass, completely hiding the Fuller's Earth, but 

it gives welcome access to the Boueti Bed and the Forest Marble above. These 

are bent up steeply against the faulted Middle Lias in the corner and can be 

studied with ease (fig. 29, p. 154). 

East of the centre of Watton Cliff a third fault, downthrowing north-west, 

enters the cliff obliquely and cuts out the Forest Marble and Upper Fuller's 

Earth, bringing up Lower Fuller's Earth in their place. Thence eastward to 

the other boundary fault, which brings up Bridport Sands close to the 

esplanade, the cliff consists of Lower Fuller's Earth, dipping inland at a steep 

angle and much slickensided. If any fossils existed in this clay they have been 

almost entirely destroyed. There is much secondary gypsum, obviously 

connected with the disturbance. 

The fault in the centre of the cliff brings up a number of hard bands of 

argillaceous limestone, which are the only representative of the Fuller's Earth 

Rock known on the coast. Unfortunately, besides being nearly vertical, they 

are much disturbed, and the succession is very difficult to interpret. Buckman 

considered that the rock-bands were merely bent over at a high angle towards 

the fault-plane, so that the beds below them could be measured off in regular 

sequence. In a number of visits to the spot, however, both separately and 

together, Mr. L. Richardson and I have come to the conclusion that the 

1 There was formerly a tiny patch of Cornbrash on the summit, since removed by coast 

erosion; the whole thickness of the Forest Marble is therefore present.


Watton Cliff, Bridport, Dorset. 

The vertical part is Upper Fuller's Earth Clay; B.B. = Boueti Bed, with 

Forest Marble above. 

Fuller's Earth Rock, Shepton Montague railway-cutting, Somerset. 

PLATE XII

FOREST MARBLE AND FULLER'S EARTH: DORSET COAST 251 

whole of the rock-bands visible in the cliff are out of place; are in fact parts 

of a fault-breccia of very large lumps, caught up in the fault. On this view 

the succession is by no means perfect and it is impossible to measure the total 

thickness. Nevertheless, it is probably safe to say that samples of all the 

types of Fuller's Earth present are represented in the jumbled rock-masses of 

the fault-breccia. 

In certain states of the beach it is possible to see further exposures of the 

rock-bands, which are full of brachiopods, appearing from beneath the shingle, 

both here and along the line of the great fault, opposite Fault Corner. 

The basal part of the Fuller's Earth is not exposed at Watton Cliff. A few feet 

of clay immediately above the Inferior Oolite, with The Scroff and Zigzag Bed, 

may be seen in the brow of the vertical cliff of Bridport Sands and Inferior Oolite 

between the mouth of the River Bredy and Burton Bradstock (fig. 29), and 

again in a more accessible position in a quarry at Burton Bradstock allotments. 

The Upper Fuller's Earth is best seen at Cliff End, east of Burton villas, 

with the Boueti Bed in the brow of the small cliff and the Forest Marble outcropping 

in the partly grassgrown bank above. It is again exposed indifferently 

at several points in the low banks of the Fleet Backwater about Langton 

Herring, together with the Boueti Bed and the greater part (in discontinuous 

sections) of the Forest Marble. (See map, p. 342.) 

The sections along the shores of the Fleet, although at first unpromising, provide 

the key to the interpretation of the disturbed succession at Watton Cliff. 

The classic exposure of the Boueti Bed, the type-locality of the name-fossil, 

is the little promontory of Herbury (or Herbeyleigh), south of Langton 

Herring. On the north-west extremity of the promontory the bed descends 

to water-level and runs gradually out under the shore. The gentle lapping of 

the waves of the backwater has washed out the fossils from the soft matrix 

until the beach has come to be largely composed of brachiopods. Perfect 

specimens of G. bouetiy together with numerous other large Rhynchonellids 

and abundant Ornithella digona and Avonothyrids may be picked up by the 

hundred. Eastwards the lower and middle portions of the Forest Marble are 

well exposed and in places highly fossiliferous. Owing to the discontinuity of 

the sections, however, it is difficult to determine the position of the several 

fossil-bands in the sequence. 

Below the Boueti Bed, in the small cliff on the north side of the promontory 

of Herbury, about 12-15 ft. of the highest beds of the Fuller's Earth can be 

seen. The unfossiliferous white cementstone band so conspicuous in Watton 

Cliff has here multiplied to several bands. The beds rise northward in the 

southern limb of the Weymouth Anticline, the axis of which runs out to sea 

about f mile to the NW., beyond Langton Herring coastguard station. The 

greater part of the Upper Fuller's Earth is concealed in the low grassy shore 

around the little bay of Herbury, but on the north side the banks begin to show 

small sections intermittently for a mile, and these afford some indication of the 

lowest beds that come to the surface in the anticline. Nearly the lowest horizon 

seen is a remarkable bank of oysters. At one place, west of the coastguard 

station, the shells form a solid mass 10 ft. thick, marked on the Survey map 

as 'masses of Ostrea acuminata in the Fuller's Earth', and recorded as that 

species by H. B. Woodward, S. S. Buckman and others. This misidentification 

has been the source of much of the trouble in the correlation of the


Fuller's Earth of Dorset; for the species bears no resemblance to the true 

Ostrea acuminata Sowerby, which marks a constant horizon below the Fuller's 

Earth Rock in North Dorset and Somerset. It is a large and peculiar variety 

or mutant of Ostrea sowerbyi Mor. and Lyc., to which the name var. elongata 

has been given by Dutertre, and its position is above and not below the local 

representative of the Fuller's Earth Rock. If the rock were present above, it 

would certainly be exposed somewhere along the shore. Instead there is a 

positive indication that it lies below ground, for one mile west of Langton 

Herring a small section shows the Elongata Bed (3 ft. thick) overlying 2 ft. of 

clay with nodules of argillaceous limestone and numbers of Rhynchonelloidea 

smithii, which is a fossil indicative of the Fuller's Earth Rock (and of the upper 

part in particular). 

Loose blocks of the Elongata Bed are also caught up in two of the faults at 

Watton Cliff. In Fault Corner an isolated patch was first discovered by Buckman, 

close to the wall of Middle Lias, and dragged up almost level with the 

Boueti Bed. Larger blocks are associated with the Fuller's Earth Rock in the 

middle fault, and in 1931 there was some evidence that the oyster bed lay 

almost immediately on the top of a large mass of the rock-bands, as is to be 

expected from the indications at Langton Herring. Buckman came to the 

same conclusion prior to 1922, although he misidentified the oysters as 

O. acuminata. l 

SUMMARY OF THE GREAT OOLITE SERIES AS EXPOSED ON THE DORSET COAST 

forest Marble': Wychwood Beds and Bradford Beds, 80-90 ft. 

Detailed stratigraphical research on the Forest Marble south of the Mendips 

still remains to be done, and a start needs to be made with the splendid sections 

on the Dorset coast. Meanwhile it is necessary to continue using the old faciesterm 

Forest Marble, although it is highly probable that a large proportion of 

the rock so called will in time be found to yield the distinctive fossils of the 

Bradford Clay (or better Bradford Beds, since, as we shall see later, the clay 

at the type-locality passes laterally into limestones of Forest Marble facies). 

The Forest Marble of the coast falls into three divisions of approximately 

equal thickness: a central block of hard, flaggy, massive, false-bedded, brokenshell 

limestone, blue-centred and oolitic, sandwiched between two predominantly 

argillaceous divisions. The clays, however, are very different 

from those of the Fuller's Earth, for they are usually greenish or brown, sandy, 

shaly, or micaceous, with numerous thin and impersistent laminae of hard, 

fissile shale or broken-shell limestone. The limestones are largely made up of 

broken valves of Ostrea sowerby, Pectinidae, &c. It is remarkable that this 

peculiar shallow-water facies persists almost unaltered near the top of the 

Great Oolite Series as far as Buckingham and recurs even farther north. 

Lately, however, evidence has been obtained showing that the conditions 

which determined the facies set in earlier in some districts than in others. 

The central mass of limestone is used locally for building and road-mending, 

so that the coast-sections are amplified by numerous quarries about Burton, 

1 S. S. Buckman, 1922, Q.J.G.S., vol. lxviii, pp. 381-2. O. sowerby, including var. elongata, 

often assumes a Gryphaeate form and shows nascent ribbing. The presence of such specimens 

at Watton Cliff no doubt accounts for Buckman's recording the Ostrea knorri Beds as well; 

repeated search by Mr. Richardson and the writer has failed to produce a single specimen of 

O. knorri from the coast-sections.

FOREST MARBLE AND FULLER'S EARTH: DORSET COAST 253 

Swyre, and Bothenhampton. The immense quarries at the last village, however, 

cited by H. B. Woodward as some of the finest sections of Forest Marble 

in the country, have long ago been abandoned. The stone is full of rolled and 

bored pebbles of argillaceous limestone, up to several inches in diameter, as 

well as ochreous clay galls. The pebbles have evidently been derived from the 

erosion of some previous deposit, but it is not clear what this deposit was. 

The most cursory examination reveals the presence of myriads of shells of 

Ostrea sozverbyi, Chlamys obscura, Camptonectes laminatus, Lima cardiiformis, 

and a Gervillia or Perna which has been dissolved away, leaving numerous 

cavities. There are also species of Navicula and other fossils, and more rarely 

Rhynchonellids (the valves separated and very difficult to detach) and an 

Epithyris (?marmotea Oppel). 

On the west end of the Herbury Promontory the lower middle part of the 

Forest Marble contains some highly fossiliferous beds, reminiscent of some 

in the Oolithe Blanche de Langrune on the opposite side of the Channel. 

They contain abundant valves of Oxytoma costata, with nests of a rather small 

Rhynchonellid, sponges, and ossicles of Apiocrinus. 

The Boueti Bed: Bradford Beds, pars. 

The richness of the Boueti Bed has already been remarked on. Although 

only 1 ft. thick, it has supplied almost enough specimens of Goniorhynchia, 

Kutchirhynchia, Ornithella, and Avonothyris at Herbury to pave the beach. 

It also contains numerous well-preserved valves of Chlamys vagans, Placunopsis 

socialis and a small oyster (rarely more than 2 or 3 mm. in diameter). At 

Cliff End, Burton Bradstock, the brachiopods are less abundant, and at 

Watton Cliff, 12 miles from Herbury, they are considerably scarcer, though 

G. boueti can always be found in moderate numbers. At the latter place the 

Boueti Bed is overlain by a separate bed crowded with Placunopsis and the 

micromorphic oysters, and yielding an occasional Dictyothyris. 

It is noticeable that the fossils of the Boueti Bed are commonly encrusted 

with Polyzoa, minute oysters, or Serpulce, sure signs of slow deposition. 

Upper Fuller's Earth Clay. 

In the mural face formed by the Upper Fuller's Earth of Watton Cliff about 

100 ft. are exposed, but the cliff is extremely dangerous and yields little information, 

for the fallen blocks cannot be properly located in the sequence. The 

clay falls away in large masses with a conspicuously conchoidal fracture, whence 

Buckman called it the Large Conchoidal Bed. Well preserved but fragile shells 

of Grammatodon, Nucula, Astarte, &c., may be collected from the debris. 

At Cliff End, Burton Bradstock (fig. 29, p. 154), the highest 50-60 ft. can 

be studied at leisure and the following section is obtainable: 

UPPER FULLER'S EARTH AT BURTON BRADSTOCK 

[Boueti Bed above.] 

4. Prominent band of hard white laminated cementstone 

3. Unfossiliferous grey clay . . . . . . . . 

2. Unfossiliferous grey clay with two thin bands of red claystone 4 ft. apart . 

1. Fossiliferous grey clay with numerous pale crumbling concretions and 

nests of fossils: abundant small gastropods— 4 Eulima 9 sp., Nucula waltoni 

Mor. and Lyc., Nucula sp., Grammatodon sp., Trigonia sp., Oxytoma 

sp., Lucina sp., Goniomeris sp.: seen to . . . . . 

ft- 

2-3 

20 

4 

c. 30


At the base of the Upper Fuller's Earth is the oyster bank of Ostrea sowerbyi 

var. elongata, already referred to. It thins rapidly from about 10 ft. near 

Langton Herring coastguard station to 3 ft. a mile farther north-west, but 

it is still several feet thick 12 miles away, at Watton Cliff. The peculiarity 

that characterizes the oysters is a ventral elongation (more correctly 

'heightening') so that full-grown specimens become the shape and size of a 

human finger. There is at the same time every gradation to the normal form 

so common in the Forest Marble. M. Dutertre informs me that he has found 

the same association of this form with the typical shapes in the Boulonnais, 

and has been accustomed to regard it as only a variety of O. sowerbyi. There 

is no real resemblance to the O. acuminata of a lower level. 

Fuller's Earth Rock. 

The Fuller's Earth Rock has previously been alleged to be absent on the 

Dorset coast, but there can be little doubt that it is represented by the 25 ft. (?) 

of argillaceous limestone and clay bands cautiously called by Buckman the 

'Brachiopod Beds'. There seem to be (so far as can be seen from the jumbled 

exposures) about 6 or 8 bands of stone, each from 6 in. to 1 ft. thick, separated 

by as many clay bands. A collection of the brachiopods has been examined by 

Miss Muir-Wood, who finds that the most abundant species, Stiphrothyris 

wattonensis,is peculiar to this locality, although associated with it are specimens 

of S. nunneyensis, which is the common species along the inland outcrop. In 

addition Rhynchonelloidea smithii and Acanthothyris powerstockensis abound, 

with occasionally an Ornithella sp. Buckman also recorded a large ammonite 

(IParkinsonites). 1 

Lower Fuller's Earth Clay and Zigzag Bed. 

As already remarked, the Lower Fuller's Earth Clay of Watton Cliff is much 

squeezed and disturbed and yields few if any fossils. Buckman distinguished 

three lithological divisions as follows: 2 

ft. 

Umber Bed; umber-coloured clay with a nodular band . . . .20 

Small Conchoidal Bed; grey clays with small conchoidal fracture, and a band 

of ochreous nodules (1 ft.) at base . . . . . . . 40 

Laminated Clays, with occasional nodules of pyrites . . . . - 5 ° 

These thicknesses are very hypothetical, and might be double or half the true 

thicknesses, since it is impossible to make accurate measurements. The Ostrea 

knorri Clay, said by Buckman to be at the top and 5 ft. thick, is probably below 

beach-level, and there is no evidence that any specimen of O. knorri has ever 

been found at Watton Cliff. Certainly it would be unlikely to occur so high 

in the series, for elsewhere it marks a constant horizon near the base of the 

Fuller's Earth, and Richardson has found it only a few feet above the Zigzag 

Bed as near as Beaminster. 3 It is probable that Buckman saw a specimen of 

Ostrea sowerbyi with incipient ribbing, a not uncommon variety. 

Also below the beach-level at Watton Cliff are some few feet of clays seen 

1 S. S. Buckman, 1922, Q.J.G.S., vol. lxxviii, p. 382. 

2 S. S. Buckman, 1922, loc. cit. 

3 L.Richardson, 1915, P.G.A., vol. xxvi, p. 70. 

no

FOREST MARBLE: NORTH DORSET AND SOMERSET 255 

at Burton Bradstock, yielding Belemnopsis bessina (d'Orb.), a belemnite 

especially common in the equivalent Marnes de Port-en-Bessin. Below this, 

and best seen in the Allotments Quarry, is the 2 or 3 in. of indurated marl 

known as The Scroff, characterized (but rarely) by Oppelia fitsca and Aulacothyris 

cucullataAt the base of all is the Zigzag Bed. 

The Zigzag Bed consists of about 6 in. of white limestone containing abundant 

ammonites. Buckman has figured the following from Burton Bradstock 

(the names are those under which Buckman figured the specimens and the 

numbers refer to plates in Type Ammonites): 

Planisphinctes planilobus . 

Polysphinctites polysphinctus 

Polysphinctites replictus . 

Procerites tmetolobus 

Ebrayiceras rursum 

Ebrayiceras jactatum 

Harpoxyites fallax . 

cccxxvn 

CCCXXII 

CCCLIX 

CDXVI 

DCCLVIII 

DCCLXIX 

CDXCIX 

(b) The Inland Outcrop to the Mendips 

Forest Marble: Wychwood Beds, Hinton Sands and Bradford Beds, 100- 

130 ft. 

The Forest Marble is exploited in numerous quarries all along the outcrop, 

but they are shallow in relation to the whole formation and show only a small 

proportion of the total thickness. Although the details vary in every quarry, 

so far as can be seen the tripartite arrangement—a central limestone block 

sandwiched between two predominantly argillaceous divisions—is maintained 

throughout Dorset and Somerset. 

The greatest thickness of Forest Marble in England, about 130 ft., is 

developed in the neighbourhood of Sherborne. In its effect upon the scenery 

hereabouts and for many miles to the north the formation is the most important 

member of the Oolites. Its escarpment builds Lillington Hill and the 

rest of the high ridge that divides the waters flowing into the Bristol Channel 

by the River Yeo from those destined for Blackmoor Vale and the Stour, which 

takes them into Bournemouth Bay. Most of the extra thickening seems to 

take place in the upper argillaceous division, which expands to over 60 ft. 

Below this, from 61-70 ft. from the top, a sandy element appears, in the form 

of foxy sands enclosing a hard calcareous grit. 2 The sands can also be seen to 

a thickness of 10 ft. at Charlton Hill, north-east of Charlton Horethorne, with 

25 ft. of the main limestone division below, consisting of typical dark, bluegrey 

shelly Forest Marble, with partings of loam, sand and clay. These are 

the first appearances of the Hinton Sands, described by William Smith at 

Hinton Charterhouse, near Bath, and traceable as far as Cirencester. 

The lower clay division has recently been well exposed in widening the 

main road up the hill a mile north-east of Bruton, where its thickness was 

estimated by Richardson and myself to be about 25 ft. At the base was shown 

a thin seam of brown, shaly, platy Forest Marble limestone containing some 

of the fauna of the Bradford Clay: Rhynchonella cf. obsoleta, ossicles of 

1 See also Gonolkites vermicuJaris S. Buck., T.A., pi. DXLVII. 

2 H. B. Woodward, 1894yJ.R.B., p. 347. He describes a complete section in a road-cutting 

at West Hill, south of Sherborne, showing the details.


Apiocrinus, and abundant Oxytoma costatay Chlamys vagans and Nucula. 

Near by, at Wincanton, numerous specimens of Goniorhynchia boueti were 

found in this bed in a boring. 1 This is the last inland record of the species. 

The distance north of Herbury is 30 miles. The Wincanton Boring also 

showed the total thickness of the Forest Marble to be 103 ft., and this thickness 

seems to be maintained fairly steadily across the Mendip region into the 

Cotswolds. 

Upper Fuller's Earth, 130-240 ft. 

According to the interpretation of the Wincanton Boring the Upper Fuller's 

Earth clay has there the prodigious thickness of 240 ft., while at Scale Hill, 

south-east of Batcombe, De la Beche estimated its thickness to be still 133 ft. 

Considerably more than 120 ft. was known to be present in the neighbourhood 

of Milborne Port, for the Stowell Boring passed through that amount 

although it was started some distance from the top of the formation. 

In spite of this great thickness, scarcely anything is known of the Upper 

Fuller's Earth of the district. Woodward remarked that it was 'well exposed 

in a brickyard north-east of Maperton, and south-east of the Cock Inn, 

Holton. About 25 ft. of grey marly clay was exposed, the beds, where dry, 

being pale and hard, and much resembling those exposed in [Watton] cliff 

near Eype\ 2 From this description it is not to be expected that the Upper 

Fuller's Earth would yield much of interest; but it would be useful to obtain 

a complete section in order to know whether the Elongata Bed is present. 

Fuller's Earth Rock, 18-35 ft. 

From the neighbourhood of Thornford, 3 miles south-east of Yeovil, the 

Fuller's Earth Rock becomes an important surface-feature, its escarpment, 

although overlooked by that of the Forest Marble, being a conspicuous element 

in the landscape. Old limekilns and quarries, some of them still worked, become 

numerous, and there are in addition three nearly or quite complete 

sections in road- and railway-cuttings, at Shepton Montague (Plate XII), at 

Laycock, north of Milborne Port, and near Blackford Lake, between Maperton 

and Charlton Horethorne. The thickness of the Rock is 35 ft. in the three 

neighbouring localities of Laycock Cutting, Stowell and Wincanton, but 

thins northward to 18 ft. at Shepton Montague and 25 ft. at Scale Hill near 

Batcombe. 

The rock is a grey or buff, cream-weathering, non-oolitic, argillaceous 

limestone, the lower part surprisingly hard and massive, and strongly suggesting 

certain of the limestones in the Great Oolite proper in Oxfordshire and 

Gloucestershire. The upper part is usually more rubbly, like Lower Cornbrash, 

and is crowded with Ornithella bathonica, O. pupa, and Stiphrothyris 

nunneyensis and S. globata. 3 Towards the top, at Charlton Horethorne and 

Maperton, Richardson has also described a bed of marl with Diastopora, 

which he calls the Polyzoa Marl. 4 

1 W. Edwards and J. Pringle, 1926, Sum. Prog. Geol. Surv. for 1925, pp. 183-8. 


3 For identifications of all Fuller's Earth brachiopods I am indebted to Miss H.M.Muir- 

Wood, who has very kindly given me much information in advance of publication. 

4 See L. Richardson, 1909, P.G.A., vol. xxi, pp. 212-13, for descriptions of sections and 

lists of fossils; also in 'Geol. Shaftesbury', Mem, Geol. Surv., 1923, p. 22.

FULLER'S EARTH: NORTH DORSET AND SOMERSET 257 

The Ornithellids in the upper part of the Rock or Ornithella Beds show great 

diversity of form and belong to a number of different lineages. They may be 

collected with the Stiphrothyrids in a perfect state of preservation at numerous 

places—Shepton Montague, Charlton Horethorne, Maperton, Alham Lane, 

Haydon, &c. 1 

The fauna of the Fuller's Earth Rock, and of this upper portion especially, 

is rich and interesting. Besides the wealth of beautifully-preserved brachiopods 

it comprises some forty-five species of lamellibranchs, of which at least 

fifteen are familiar Lower Cornbrash species. In any collection from one of 

the Fuller's Earth Rock quarries of Somerset may be noticed such typical 

Lower Cornbrash shells as Lima duplicata (Sow.), L. rigidula Phil., Entolium 

rhypheum (d'Orb.), Ostrea (Lopha) costata Sow., &c., while even a species 

usually considered so characteristic of the Lower Cornbrash as Pseudomonotis 

echinata (Sow.) seems to be absolutely indistinguishable when it occurs at 

this lower horizon. This striking community of fauna may well be connected 

with the strong lithic resemblance between the two rocks. 

A number of peculiar and highly characteristic Cadicone ammonites are 

also tolerably abundant. They have been studied comprehensively by Buckman, 

who founded for their reception the family Tulitidae, with genera Tulites, 

Tulophorites, Madarites, Pleurophorites, Rugiferitesy Sphceromorphites, Bullatimorphitesy 

Morrisites, and Morrisiceras. 2 Unfortunately he had no fieldknowledge 

of the circumstances or order of their occurrence and no practical 

familiarity with the Fuller's Earth Rock, but he arranged them in a hypothetical 

order according to their matrices. 3 This risky procedure, which he 

had attempted in 1913 with the museum specimens from the Yorkshire 

'Kellaways Rock' (see below, p. 363), led to results incongruous with the 

field-evidence obtainable in the exposures throughout Somerset and North 

Dorset, and it deprives the stratigraphical results of any value. In spite of the 

impressive table of hemerae and their corresponding matrices, by which the 

epiboles were supposed to be recognizable, it must be understood that there is 

at present no field evidence whatever for the numerous ammonite-horizons 

within the Fuller's Earth Rock. 

Without describing a single section in support of his conclusion, Buckman 

divided up the Fuller's Earth Rock into two portions, Milborne Beds above 

and Thornford Beds below. 4 The Milborne Beds were said to be 'brown 

(ironshot) limestones' and the Thornford Beds 'whitish, chalky limestones'. 

It must not be thought, however, that the upper or Ornithella Beds are to be 

called Milborne Beds and the more massive lower portion Thornford Beds. 

If we look through Buckman's records of the localities of the ammonites 

studied, we find that he used the names in quite a different sense. 5 He 

assigned to 'Milborne Beds' all the ammonites, from whatever horizon, labelled 

as from any of the principal Fuller's Earth Rock localities of Somerset, including 

all the specimens from Milborne Wick (Laycock railway-cutting near 

Milborne Port Railway Station) and Shepton Montague railway-cutting, at 

1 See note 4 on previous page. 

2 S. S. Buckman, 1921, T.A., vol. iii, p. 43. For figures of Tulites and Morrisiceras 

from Haydon, Milborne Wick and Shepton Montague see T.A., plates CLXVII, CCLXIX, 

CCLXXIV, CCLXXXV, CCCLXXVII. 3 1921, loc. cit., pp. 50-1. 

4 S. S. Buckman, 1918, Pal. Indica, iii (2), p. 237; and 1921, T.A.y vol. iii, p. 51. 

5 1921, loc. cit., pp. 43-9.


both of which places the whole of the Fuller's Earth Rock is exposed. At 

these places the ammonites occur as commonly in the lower part of the Rock 

as in the higher; therefore the whole of the Fuller's Earth Rock throughout 

the main escarpment of Somerset must be classed as 'Milborne Beds'. 

The only locality where Buckman recognized 'Thornford Beds' was Troll 

Quarry, near Thornford, Dorset, 3\ miles south-west of Sherborne. 

The Fuller's Earth Rock of Troll Quarry is certainly peculiar. Buckman 

published a description of the quarry five years later, 1 and it was the only 

exposure of Fuller's Earth Rock he ever described. From his experience of the 

museum material from other Fuller's Earth Rock localities he concluded that 

'the ammonoid fauna yielded by Troll quarry is almost, if not quite, unique 

in England'. It would seem, therefore, that this one exposure affords a glimpse 

of beds that are not developed in fossiliferous facies anywhere along the 

Somerset outcrop; and from such field evidence as there is it would appear 

also that they may be, as Buckman believed, on a somewhat lower horizon 

than the ordinary Fuller's Earth Rock, or, as he called it, Milborne Beds. 

Troll Quarry is only some 8 ft. deep. It displays five bands of nodular, 

somewhat rubbly to very hard, w T hitish, chalky limestone, separated by grey, 

white-weathering marl. As a whole the beds are monotonous and poorly 

fossiliferous (any attempt to recognize the horizon of specimens by the 

matrix being of very doubtful value) and the only common fossils are casts 

of Pholadomya lyrata. One band contains small Rhynchonelloidea sp. and a 

Pseudomonotis. Mr. Richardson and I have found two specimens of the almost 

spherical Sphceromorphites (the lowest hemeral index of Buckman's hypothetical 

sequence) in situ only 2 ft. from the top of the section. It is therefore 

very doubtful if the existence of any distinct epiboles will ever be established 

in this quarry; it seems more probable that the peculiar ammonites lived 

contemporaneously and together form a single faunizone. 2 

Unfortunately the quarry is an isolated one. The nearest other exposure 

is about 2 miles away on the opposite side of Thornford, where a cutting on 

the Sherborne road shows 5 ft. of the base of the Fuller's Earth Rock and about 

10 ft. of the top of the Lower Fuller's Earth Clay. Both rock and clay appear 

to be unfossiliferous except for some minute Rhynchonellids, but the rock is 

of a similar type to that at Troll. Another exposure of similar rock, even more 

unfossiliferous, resting on Fuller's Earth Clay, has also been revealed an equal 

distance to the WNW., in a cutting on the main road south of Yeovil. Perhaps 

it is significant that no trace of any Ostrea acuminata Bed appears below the 

rock in either of these sections, although a thick bed crowded with this oyster 

everywhere underlies the normal Fuller's Earth Rock or 'Milborne Beds' 

throughout Somerset, for at least 30 miles from the neighbourhood of 

Milborne Port to the district around Bath. It is possible, therefore, that the 

Thornford Beds are below the main horizon of Ostrea acuminata. 

Lower Fuller's Earth Clay and Zigzag Beds, i20-?200 ft. 

The Lower Fuller's Earth Clay was completely fathomed by the borings at 

Wincanton and at Stowell. At Wincanton it proved to have a thickness of 

1 S. S. Buckman, 1927, T.A., vol. vi, p. 50. 

2 For figures of the Troll ammonite fauna see T.A., pi. CCCLXVII-CCCLXXI and CCCXXXVIII. 

Dr. Spath accepts far fewer genera than Buckman ; see Med. om Granland, 1932, vol. LXXXVII, 

no. 7, pp. 9-15.


120 ft. At Stowell it was at least 57 ft. thicker, but there has been some confusion 

regarding the interpretation of the relevant part of the record, for the 

lower part of the clay yielded ammonites said by Buckman to be suggestive 

not only of the zigzag but also of the truellei zone, 1 while nothing definite was 

found in the top of the thick Inferior Oolite limestones below. Since, however, 

the truellei and zigzag (and presumably schloenbachi) zones are definitely 

represented by limestones all along the neighbouring outcrop, which passes 

only a mile from the Stowell Boring, 2 it seems highly probable that the 

ammonite supposed to be indicative of the truellei zone was misidentified. 

The suggestion might be made that in a core-sample any Oppelid might be 

mistaken for a Strigoceras; in fact a specimen figures in the same list as 

'Oekotraustes} (or Strigoceras)\ from the Fuller's Earth Rock. 

In these circumstances we may probably conclude with safety that there 

was nothing unusual about the Lower Fuller's Earth in the Stowell Boring, 

and that, as elsewhere, the upper part of the zigzag zone was represented by 

clays and the lower part by limestones. As the limestones which appear to 

belong to the zigzag zone in the near-by outcrop are probably about 25 ft. 

thick, we ought to add about that amount to the Lower Fuller's Earth, making 

the total thickness some 200 ft. 

About 5 miles north of Stowell is the Wincanton Boring, where the thickness 

of the Lower Fuller's Earth Clay was proved to be 120 ft. (+an unknown 

amount for limestone of zigzag date ?), and 6 miles farther at Scale Hill, 

near Batcombe, De la Beche estimated it to be only 21 ft. (fig. 48, p. 264). 

With this low estimate H. B. Woodward agreed, although he was not able 

actually to check it. 3 Over the end of the Mendips, as we shall see, the thickness 

certainly diminishes still further. Therefore it appears that, unlike the 

Upper Fuller's Earth Clay, the Lower Clay diminishes rapidly northward 

along the Somerset outcrop. 

At the top of the Lower Fuller's Earth, immediately beneath the Rock, is 

the most characteristic palaeontological horizon in the whole formation, the 

Ostrea acuminata Beds. As much as 6 or 7 ft. of the top of the clay may be 

crowded with shells, massed together as a typical oyster-bank. At this horizon 

they are the true O. acuminata of Sowerby, very sickle-shaped and uniformly 

small, altogether different from the oysters of the Elongata Bed in Dorset. 

The true Acuminata Bed does not seem to have been recognized south of 

Milborne Port; but thence northward it is continuous to beyond the Mendips, 

having been seen, always in the same position, at Laycock 4 and Stowell, 5 

Holton, 6 Wincanton, 7 Shepton Montague, 8 Alham Lane near Batcombe, 9 and 

close to the flanks of the Mendips, in the escarpment of the Fuller's Earth 

Rock in Chesterblade Lane, south of Doulting Bridge Quarry. 9 

The bulk of the Lower Fuller's Earth Clay, like the Upper, is hardly ever 

1 S. S. Buckman, in J. Pringle, 1910, Sum. Prog. Geol. Surv. for 1909, p. 70. 

2 For a detailed account of neighbouring exposures see L. Richardson in H. J. Osborne 

White, 1923, 'Geol. Shaftesbury', Mem. Geol. Surv., pp. 11-18. 


4 L. Richardson, 1923, 'Geol. Shaftesbury', Mem. Geol. Surv., p. 22. 

5 J. Pringle, 1910, loc. cit. 

6 H. B. Woodward, J.R.B., p. 236. 

7 Edwards and Pringle, loc. cit. 

8 A fine exposure, where O. acuminata may still be collected in hundreds (PI. XII). 

9 L. Richardson, 1909, P.G.A., vol. xxi, p. 212. 

Hn4371 T


exposed and is almost unknown. It was completely penetrated in the Stowell 

and Wincanton Borings, but yielded nothing of interest. 

The basal layers, like the topmost, are better known, for they are sometimes 

present in the brow of quarries opened for the underyling Inferior Oolite. 

Some of these exposures show another interesting oyster-bank, the Ostrea 

knorri Bed. This little oyster was first described from the borders of Germany 

and Switzerland, and it forms conspicuous oyster beds in many places in 

South Germany, Lorraine, &c. It is almost gryphaeate in form, the left valve 

very convex and the right valve small and flat, while an altogether distinctive 

appearance is given it by the presence of numerous delicate radial ribs on the 

left valve only. It has been considered so distinct from all other oysters that 

one palaeontologist has made it the type of a new genus, Catinula. 1 

The Knorri Bed has been seen at the base of the Fuller's Earth resting on 

the Zigzag Bed, and this in turn on the limestones of the Microzoa Beds 

{schloenbachi zone) in the side of a road at North Poorton, only 6 miles inland 

from the coast at Burton Bradstock, and again 5 miles farther NW., in the 

roadside midway between Beaminster and Broad Windsor. 2 Day recorded 

it as long ago as 1864 at Powerstock, only 5 miles from the coast. 3 It occurs 

again at Stoford, south of Yeovil, 4 still close down upon the Zigzag Bed. 

Thence it does not seem to have been met with again until the Bridge Quarry, 

Doulting, where Richardson has called attention to the enormous abundance 

of it, once more at the very base of the Fuller's Earth Clay. 5 

At the extremities of the district, where the Knorri Bed is found, the base 

of the Lower Fuller's Earth is formed by the 3-6 in. band of white limestone 

with ammonites of zigzag date, as at Burton Bradstock; it is rich in ammonites 

of the genus Zigzagiceras (Z. zigzag, Z. subprocerum, Z. pollubrum, Z. rhabdouchus, 

Z. phaulomorphus, Z. crassizigzag, &c.) with Oppelia fusca (Quenst.) 

and its allies. 6 The most richly fossiliferous localities are Grange Quarry, 

Broad Windsor, Crewkerne Railway Station, Haselbury Mill Quarry, 7 and 

Doulting Bridge Quarry. Immediately succeeding this but below the Knorri 

Bed can usually be recognized 2 or 3 in. of hardened marl known as The 

Scroff, which occasionally yields Oppelia fusca. 

In the central area around Sherborne and Milborne Port, the zigzag zone 

seems to be partly represented by up to 25 or 30 ft. of whitish limestones, 

which have been called the CRACKMENT LIMESTONES. 8 They first appear, 

in argillaceous development and interbedded with clays, at King's Pit, Bradford 

Abbas, where, as already mentioned, Richardson has obtained ammonite 

evidence that they belong to the zone of Zigzagiceras zigzag. 9 Limestones 

which he believes to be mainly of this age overlie the truellei zone to a thick- 

1 L. Rollier, 1911, Fades du Dogger, p. 272. This should serve to indicate its distinctness 

from Ostrea (Lopha) costata Sow. which some have doubted. Lopha is entirely different, both 

valves being convex and strongly plicated. 

2 L. Richardson, 1928, Proc. Cots. N.F.C., vol. xxiii, pp. 173, 181. 

3 E. C. H. Day, in K. von Seebach, 1864, Der Hannoversche Juray p. 93. 

4 Shown me by Mr. L. Richardson (see fig. 45, p. 233). 

5 L. Richardson, 1907, Q.J.G.S., vol. lxiii, p. 393. 

6 For figures of ammonites from the Zigzag Bed of the first two localities see S. S. Buckman, 

T.A.y pis. CLIII, CLXXIII—IV, CCLIX, CCC, CCCXXXV, CCCLI, CCCLXXVI, DXLVI, DXCV, DCXXIII-IV, 

DCXLIII, and below, PI. XXXV. 

7 L. Richardson, 1918, Q.J.G.S., vol. lxxiv, p. 166. 

8 L. Richardson, 1923, in 'Geol. Shaftesbury', Mem. Geol. Surv., pp. 16-18. 

9 L. Richardson, 1911, P.G.A.y vol. xxii, p. 262.


ness of 25 ft. at the Halfway House, between Yeovil and Sherborne (p. 234), 

and succeed the Rubbly Beds above the Sherborne Building Stone north and 

east of Sherborne. Here, in the type-sections at Crackment (or Crackmore) 

they are 20 ft. thick, and yield Pholadomya sp. in some abundance, Belemnopsis 

bessina, Spharoidothyris and Pleuromya\ and near by, at Goathill, he 

obtained a specimen of Zigzagiceras procerum S. Buck., indicating the zigzag 

zone. 1 As usual, however, where the limestones are thickly developed they 

are much poorer in fossils than where they are attenuated. 

The restriction of the thick development of the Crackment Limestones to 

the centre of the area around Sherborne and Milborne Port, while towards 

the Dorset coast they thin dow r n to a 6-in. fossil-band or Zigzag Bed, is 

remarkable. It suggests that the Mendip and Weymouth Axes were exercising 

some control on the sedimentation during the zigzag hemera. At present 

evidence seems to be lacking to show whether the North Devon Anticline and 

the Cole Syncline had any similar effect. 

II. THE MENDIP AXIS 

The Mendip Axis certainly continued to cause paucity of sedimentation, 

accompanied by overlaps, until the end of Fuller's Earth times. The northerly 

overlap of the Lower Fuller's Earth by the Fuller's Earth Rock, indicated by 

the reduction of the former from 120 ft. at Wincanton to 21 ft. at Scale Hill 

near Batcombe, is continued over the axis until at Bonneyleigh Hill, 2 miles 

north-east of Frome, the Lower Fuller's Earth is only 8 ft. thick. 2 At the same 

time the Fuller's Earth Rock is reduced in thickness to 10 ft. and the Upper 

Fuller's Earth to about 20 ft. (as compared w r ith 25 ft. and 133 ft. at Scale 

Hill), and so about Frome the whole formation is not much more than 35 ft. 

thick. 3 For a considerable distance near Whatley it is mapped as overstepping 

on to Carboniferous Limestone (fig. 13, p. 70). 

The Rock continues to be highly fossiliferous, yielding at Egford Bridges, 

Whatley and Bonneyleigh Hill (map, fig. 13) the usual abundance of Ornithella 

bathonica, O. pnpa, Stiphrothyris globatay Rhynchonelloidea smithii and 

lamellibranchs. The Acuminata Bed seems to disappear over the crest of the 

axis, but the oyster occurs sparingly in the Lower Fuller's Earth. 

About three miles north of the Mendip Axis (3 miles north-west of Bonneyleigh 

Hill) a boring at Hemington was started in Upper Fuller's Earth Clay 

and, after penetrating about 30 ft., proved a thickening of the Fuller's Earth 

Rock to 15 ft. and of the Lower Fuller's Earth Clay to 40 ft. 4 These thicknesses, 

so quickly regained, are maintained with but little increase northward 

to beyond Bath. Immediately below the Fuller's Earth Rock in the Hemington 

Boring the Acuminata Bed, ii- ft. thick, was met with again, as on the south 

of the axis. 

It is instructive to compare with these figures the thicknesses proved in 

the Westbury Boring. This is situated only a mile or two south of the presumed 

underground continuation of the Mendip Axis, but some miles down 

the dip slope, 4 J miles east of Bonneyleigh Hill. It proved the Lower Fuller's 

1 L. Richardson, 1923, in 'Geol. Shaftesbury', Mem. Geol. Surv.y pp. 17-18. 

2 L. Richardson, 1909, P.G.A., vol. xxi, p. 219. 

3 H. B. Woodward, 1894, J-R.B., p. 239. 

4 C. Cantrill and J. Pringle, 1914, Sum. Prog. Geol. Surv. for 1913, pp. 98-101.


Earth Clay to have the same thickness (40 ft.) as at Hemington, but the Fuller's 

Earth Rock to be thicker (21^ ft.). The Upper Fuller's Earth Clay, however, 

showed the surprising thickness of 146 ft., or rather more than at Scale Hill. 1 

Thus it would appear that the attenuation of the Fuller's Earth from east to 

west, up the dip-slope, is of greater magnitude than the local thinning at 

right angles to this direction, over the Mendip Axis. 

A tabulation of the figures discussed in this and the foregoing sections may 

make the matter clearer (the thicknesses are in feet): 

South. Mendip Axis. North. East. 

! 1 Bonney- 

! 

Wincan- 1 Scale ' leigh i Heming- 

Stowell. ton. I Hill. Hill. ton. I Westbury. 

Upper Fuller's 

1 

i 

Earth ! (120 + ) 24O : 133 c. 20 (32 + ) ! 146 

Fuller's Earth 

Rock 35 35 25 c. 8 15 2Xl 

Lower Fuller's 

Earth ?200 I20 21 8 40 40 

The Forest Marble seems to undergo no noteworthy change in its course 

over the axis. It maintains the same thickness of 90-100 ft. and forms a 

prominent escarpment from near Cranmore, past Marston Bigot to Frome. 

The Hinton Sands have been exposed at Marston Bigot, and the Bradford 

Fossil Bed with Ornithella digona was met with at the base in a boring at 

Buckland Denham, immediately north of the axis. 2 The thickness of the 

Forest Marble in the Westbury Boring was 91 ft. 

III. THE COTSWOLD HILLS 

About 2 miles north-east of Hemington, and some 4 miles north of the 

nearest point on the Mendip Axis, the Great Oolite limestones begin to make 

their appearance between the Fuller's Earth and the Forest Marble. 

At first they comprise only a few feet of rubbly oolite seen ir* old quarries 

between Wellow and Norton St. Philip, north-east of Hassage and east of 

Lower Baggeridge (map, fig. 13, p. 70). They rest upon the clays and earthy 

limestone of the Fuller's Earth and are overlain by Forest Marbles 

Within 3 or 4 miles to the north, around the south and west of Bradfordon-Avon, 

in the ancient quarries of Murrel or Murhill near Winsley, Avoncliff 

near Upper Westwood, and at Monkton Farleigh, from 45 to 80 ft. of 

oolites, freestones and ragstones are to be seen. Hereabouts and for some 

miles northward the Great Oolite yields the famous Bath Stone, and hence 

the formation, w r ith the Forest Marble above, ranges continuously through 

the Cotswolds and Oxfordshire into the Eastern Counties. Indeed, in the 

Cotswolds it has by far the widest outcrop of all the Oolites, covering the 

entire dip-slope from the Cornbrash fringing the Oxford Clay Vale to the 


2 H.B.Woodward, 1894, J.R.B., p. 350. 

1 Ibid., p. 260.

INCOMING OF THE GREAT OOLITE LIMESTONES 263 

highest plateaux in the centre of the North and Mid-Cotswolds and lapping 

up to the edge of the escarpment above Bath, Wotton under Edge and Stroud. 

The average width from Bath to Burford is 8-10 miles and tongues extend 

northward to Condicote, 15 miles from the Cornbrash. 

The question, to what the Great Oolite is equivalent over and south of the 

Mendip Axis, has given rise to numerous speculations. If exposures of the 

Fuller's Earth in the Cotswolds were as numerous and complete as those displaying 

the Great Oolite, the problem might be easily solved. But unfortunately 

wells and borings and chance outcrops where cattle have worn paths 

down steep banks provide the only sections. The commercial exploitation 

of the Fuller's Earth is confined to a small area round Bath and the workings 

are restricted to the Upper Fuller's Earth Clay. 

In recent years it has been fashionable to correlate the Great Oolite limestones 

with the Fuller's Earth Rock. The basis of this correlation is the 

announcement by Buckman that certain ammonites are common to the two 

formations. In 1921 he wrote: 'The family [Tulitidae] is of particular interest 

as showing the contemporaneity of the Fuller's Earth Rock of South England 

with the Great Oolite of Gloucestershire-Oxfordshire, and thus that the 

Fuller's Earth Rock is later, not earlier, than the Stonesfield Slate.' 1 Buckman's 

reputation at that time was so high that the statement, unsupported by any 

field-evidence, soon came to be repeated as if it were an expression of proven 

fact. In reality the question is an extremely difficult one—by far the most 

difficult remaining in British Jurassic stratigraphy—and any dogmatic pronouncements 

are the last thing needful. 

William Smith regarded the Great Oolite as distinct from both the Forest 

Marble and the Fuller's Earth, as shown by a table made in 1819, illustrating 

the strata beneath the Cornbrash in Dorset: 2 

rClay 

[Forest Marble] ( Forest Marble 

l Clay 

Place of the Upper [Great] Oolite 

(Clay 

[Fuller's Earth] Fuller's Earth Rock 

I Clay 

Since the critical area for any inquiry is that about Bath and the South Cotswolds, 

the country which William Smith mapped in detail and knew so well, 

his conclusion is not to be lightly dismissed. 

A thorough examination was made by H. B. Woodward and published in 

The Jurassic Rocks of Britain. Having satisfied himself that the Great Oolite 

could not pass into the Forest Marble, as some had supposed, he made a 

careful investigation of its relations to the Fuller's Earth, and in particular to 

the Fuller's Earth Rock. 

'The notion that the two might be portions of one formation possessed me for 

some time,' he wrote, 'but it was dispelled when I came to examine the ground at 

Bath. In several places where the Fuller's Earth Rock had become too attenuated 

1 S. S. Buckman, 1921, T.A., vol. iii, p. 43. 

2 Geol. View and Section through Dorset and So?nerset, 1819; quoted by H. B. Woodward, 

Sg^J.R.B., p. 260.


to be shown on the map it is nevertheless present; as I found . . . between Wellow 

and Norton St. Philip; as the Rev. H. H. Winwood pointed out to me on the slopes 

of Lansdown, and as Prof. Hull has shown to be the case at Slaughterford, N.E. of 

Bath. It is therefore clear that the Great Oolite overlies the Fuller's Earth Rock in 

the neighbourhood of Bath and Bradford-on-Avon. At the same time this rock 

maintains a fairly uniform character of white marly limestone, and contains a similar 

assemblage of fossils, 1 in its range from Dorsetshire to Somersetshire, while it merges 

upwards and downwards into the marly clays of the Fullonian formation, and is of 

varying thickness and importance. 

'Hence', he concluded, 'it is quite possible that south of Bradford-on-Avon the 

lower portion of the Great Oolite may be replaced to some extent by the Upper 

Fuller's Earth Clay. More than this I am not prepared to say.. . . The evidence is in 

favour of the mass of the Great Oolite (over part at any rate of the Dorsetshire region) 

having been eroded, and there is consequently a local break between the Forest 

Marble and Fullonian formation, marked by the rich fossil-bed [the Boueti Bed] 

which has been identified with the Bradford Clay.' 2 

Evidence subsequently collected confirms these opinions. The most telling 

contribution, ignored by Buckman, was Richardson's announcement that the 

Fuller's Earth Rock not only underlies the Great Oolite and a considerable 

thickness of Upper Fuller's Earth Clay as far along the Cotswold scarp as 

Dyrham, 2 miles north-west of Marshfield, but that it abounds in the same 

characteristic assemblage of Ornithellids and Stiphrothyrids and Rhynchonelloidea 

smithii as throughout Somerset. 3 More recently traces of a similar 

rock, still with Stiphrothyrids but less the Ornithellids and Rhynchonellid, 

and still closely associated with and apparently overlying a bed densely 

packed with Ostrea acuminata, have been recognized 13 miles farther north, 

at Symond's Hall Hill above Wotton under Edge. 4 At both of these places 

the rock is succeeded by a considerable thickness of Upper Fuller's Earth 

Clay, above which follows the steeper slope of the Great Oolite limestones, 

with their numerous quarries, some of which show the Stonesfield Slate 

Series at the base. Sandy and fissile beds on the same horizon as the Stonesfield 

Slates have long been known to extend as far south as Bath and Midford, 

always overlain by the Great Oolite and underlain by the Upper Fuller's 

Earth 5 (see table, fig. 48). Thus it can be said to have been established ten 

years before Buckman made his new correlation, that the Fuller's Earth Rock, 

recognizable by a rich assemblage of brachiopods as well as by its lithology, 

is a continuous stratum from the neighbourhood of Sherborne to north of 

Marshfield in the South Cotswolds. This stratum appears to be as fully 

entitled to be considered synchronous throughout its area of occurrence as 

almost any bed containing mollusca and brachiopods; and for at least 10-12 

miles it is overlain by Upper Fuller's Earth Clay, Stonesfield Slate Series and 

Great Oolite (Bath Freestone), one above another in constant succession 

(see fig. 48). 

The reappearance of a few species of ammonites in the Great Oolite limestones, 

apparently identical with some of those in the Fuller's Earth Rock, is 

1 The italics are mine. 

2 H. B. Woodward, 1894, J.R.B., pp. 258, 259, 260. 

3 L. Richardson, 1910, Proc. Cots. iV.F.C., vol. xvii, p. 78. 

4 L. Richardson and W. J. Arkell, field-notes. 

5 H. B. Woodward, 1894, J.R.B., p. 266.


remarkable, but it is doubtful whether it has the particular significance 

attached to it by Buckman. The ammonite fauna of the Fuller's Earth Rock of 

Dorset and Somerset is a rich one, of which the majority of the species are 

not found in the Great Oolite. The possibility has not yet been explored that 

the forms in the Great Oolite may be unrelated homceomorphs of those in 

the Fuller's Earth Rock; but more probably they may be long-ranged 'zonebreakers'. 

1 Either supposition involves less difficulties than the theory that 

the Fuller's Earth Rock, with its rich brachiopod and lamellibranch assemblages 

distributed from end to end of its outcrop, is a diachronic stratum. 

The apparent absence of ammonites from the Fuller's Earth Rock north of the 

Mendips is at least partly explicable by the poverty of exposures. If quarries 

and railway-cuttings were as numerous as in Somerset and Dorset it is highly 

probable that ammonites would have been found as well as the far more 

abundant lamellibranchs and brachiopods. In the Great Oolite north of the 

Mendips, in which exposures are abundant and actively worked, on the other 

hand, the Fuller's Earth Rock brachiopods have never been found and the 

characteristic lamellibranchs are replaced by a different assemblage. 

A description of the Great Oolite Series of the Cotswold province becomes 

largely a description of the Great Oolite limestones. A great deal is known 

of their detailed development, thanks to numerous quarries and a series of 

long railway-cuttings. In the south abundant information is supplied by the 

great quarries and mines in the Bath Freestone south and east of Bath, about 

Corsham, Box and Bradford-on-Avon, as well as by the approach cuttings to 

Box Tunnel, on either side of Corsham Railway Station. This area is classic 

ground since the work of William Smith and J. Sowerby. A few miles farther 

north are the long and instructive cuttings on the South Wales line at Acton 

Turville and Alderton, described so lucidly by Prof. Reynolds and the late 

A. Vaughan, and by H. B. Woodward. Then comes the classic region of 

Minchinhampton, the scene of the lifelong labours of J. Lycett, where a 

freestone like the Bath Stone has been worked in extensive quarries and 

whence Lycett and others obtained an unrivalled collection of perfectlypreserved 

mollusca, figured in Morris and Lycett's Monograph of the Mollusca 

from the Great Oolite (1850-3). Only a few miles beyond this are the extensive 

railway-cuttings on the Swindon and Stroud line north-west of Kemble, with 

the Sapperton Tunnel. Another 8 miles farther the Swindon and Cheltenham 

line provides yet another complete section between Chedworth and Cirencester, 

which has been minutely described by Richardson. Finally, the 

development of the formation in the North Cotswolds is clear from the 

Hampen cutting, near Notgrove, on the Banbury and Cheltenham railway, 

also described by Richardson. In these sections and in numerous lesser 

quarries, the following subdivisions are to be recognized: 

1 Apparent increase in the range may be the effect of accelerated deposition during the 

biochron of the species, as explained in Chapter I, p. 35. It is not necessary to suppose that 

the biochron was any longer than the average although the biozone is much larger and 

embraces several faunizones.

FOREST 

/ 

MARBLE 

BRADFORD 

SUMMARY OF GREAT OOLITE SERIES: COTSWOLDS 267 

THE GREAT OOLITE SUCCESSION IN THE COTSWOLDS 

[Cornbrash above] 

Stratal Divisions. Thickness. Principal Invertebrate Faunas. 

WYCHWOOD BEDS with 

HINTON SANDS , 

BEDS and 

ACTON TURVILLE ; 

BEDS j 

! 

Ft. 

50-100 Epithyris marmorea (Oppel) and 

Forest Marble facies-fauna. 

0-50 Ornithella digona (Sow.), Dictyothyris 

coarctata (Park.), Rhynchonella 

obsoleta Da v., Epithyris 

bathonica Buck., Apiocrinus parkinsoni, 

&c., &c. 

/ GREAT KEMBLE BEDS J 10-30 Epithyris oxonica Arkell, corals, 

&c. Also F. M. facies-fauna. 

OOLITE 

LIMESTONES 

/SANDY 

/ 'SLATE' 

/ BEDS 

THE WHITE LIMESTONE ! 

HAMPEN MARLY BEDS 

(in the north only) j 

TAYNTON and MIN- 

CHINHAMPTON 

(? BATH) FREESTONES 

STONESFIELD SLATE 

BEDS 

| UPPER FULLER'S EARTH CLAY (with the 

Fuller's Earth of commerce) 

FULLER'S EARTH ROCK (in the south 

only) 

LOWER FULLER'S EARTH CLAY, WITH 

UPPER ESTUARINE CLAY IN THE 

NORTH-EAST 

/CHIPPING NORTON LIMESTONE 

/ (in the north only) 

40-?6o 

1 

| 

Epithyris oxonica, Nerinea eudesii 

Mor. and Lyc., corals, &c., Aphanoptyxis 

bladonensis Ark. near top. 

Burmirhynchia hopkinsi (Daw) and 

1 Ornithella digonoides Buck. 

0-30 Rhynchonella concinna (Sow.) and j 

! Ostrea sowerbyi Mor. and Lyc. 

15-30 | Rich fauna of lamellibranchs and j 

j gastropods; the main source of 

j the fossils figured by Morris and 

Lycett. 

5-3O Ostrea acuminata, O. sowerbyi, 

Rhynchonella spp., and Stiphrothyris 

spp. in 2 bands at the top. 

| In the slate, Trigonia impressa ! 

Sow., Gervillia ovata Sow., Gra- 

! cilisphinctesgracilis. See. 

i 

| ?i0-?50 

j 0-15 Ornithella bathonica, Stiphrothyris 

globata, S. nunneyensis, Rhynchonelloidea 

smithii, &c. 

j 

0-20 

[Clypeus Grit belowl 

Ostrea acuminata (without sowerbyi) 

\ in a band at the top. 

Oppelia fusca, Ostrea knorri (both 

very rare). 

Zigzagiceras zigzag at the base of 

the clay in the south. 

SUMMARY OF THE GREAT OOLITE SERIES OF THE COTSWOLDS 

Wychwood Beds with Hinton Sands = Forest Marble Proper. 

The Forest Marble enters the district and passes on through the Cotswolds 

with but little change. Despite innumerable minor variations its peculiarities 

render it generally recognizable at a glance. The thickness is 80-90 ft. in the 

south, in the Bradford-on-Avon district, 105-120 ft. in the Alderton cuttings, 

and probably at least 70 ft. about Cirencester and Fairford, but thence eastward 

it becomes thinner rather rapidly, until at Witney, over the Oxfordshire


border, only 8 ft. are left. This seems to be due to overstep by the Cornbrash. 

As a rule the three major divisions, a central limestone mass sandwiched 

between two predominantly clayey series, are recognizable over the southern 

part of the area. In addition, as far north as Cirencester, a fourth division is 

highly characteristic, the Hinton Sands of William Smith. 

The Hinton Sands, as we have seen, first make their appearance at Sherborne, 

but are discontinuous. They can be traced from Wanstrow and Marston 

Bigot on the south side of the Mendip Axis, round the eastern end of the 

Carboniferous tract by Frome, until they thicken on the north side of the 

axis to 30 ft. about Hinton Charterhouse, Buckland Denham and Rudge. 

Pits show up to 25 ft. of white and buff sands with large doggers of fissile 

calcareous sandstone, devoid of fossils except some microzoa, and looking 

more like the Lower Calcareous Grit than part of the Forest Marble. Farther 

north they are exposed east of Castle Combe, at several places about Malmesbury, 

and in the first railway-cutting on the main line north of Kemble. 

Formerly they w r ere also to be seen at Sandy Lane, south of Cirencester. 

The stratigraphical position of the sands is in the upper part of and above 

the central limestone division of the Forest Marble. Above come clays with 

flaggy and sandy or broken-shell limestones, generally full of Ostrea sozverbyi, 

Camptonectes laminatus, C. rigidus, &c. About Malmesbury, however, much 

of the limestone becomes sandy, for exposures near the station and at Brokenborough 

show thick beds of white sands and flaggy, concretionary sandstone, 

mixed with bands of broken-shell limestone, resting on 20 ft. of ripplemarked, 

flaggy calcareous gritstones and shales. In some places, as at Foxley 

Road Quarry, Malmesbury, Pickwick, near Corsham, and in the Kemble 

railway-cutting, the upper argillaceous division is either wanting or is almost 

entirely replaced by sands, which extend up to the Cornbrash. The most 

likely explanation is that the Cornbrash has begun its overstep and has cut 

out the superior beds. 

Down the dip-slope, at Bradford-on-Avon and Corsham, in the direction 

in which deeper water presumably lay, there is little or no sign of the Hinton 

Sands, the only representative being a relatively small thickness of sandy 

shales with thin bands of sandstone, as seen at Pound Pill, near Corsham 

Railway Station. 

A highly interesting feature, found only at Pickwick, near Corsham, is 

a thick band of grey, shelly and lignitiferous Forest Marble limestone full of 

the largest Bathonian brachiopod, Epithyris marmorea (Oppel). This is the 

type-locality of the species, 1 and it is not found abundantly or well-preserved 

anywhere else. The bed yielding it is at the very top of the Forest Marble, 

within 6 ft. of the Cornbrash, from which it is separated by clay and sandy 

shale. Buckman in consequence gave to the Forest Marble at this locality a 

special stage-name 'Corshamian', the meaning of which is not clear, since 

the bed with the Epithyris seems to occur in the upper part of the equivalents of 

the Hinton Sands, which in the same work he called 'Hintonian'. 2 Moreover, 

large implicate Epithyrids, perhaps identical with E. marmorea, occur rarely 

in the central limestone block of the Forest Marble in Dorset. It is not improbable, 

however, that these beds seen about Corsham and Hinton Charter- 

1 The type is the specimen figured by T. Davidson, Mon. Brit. Foss. Brachiopoda, pt. 3, 

pi. ix, fig. 4. 2 S. S. Buckman, 1927, Q J.G.S., vol. lxxxiii, p. 7.

BRADFORD CLAY: WILTSHIRE 269 

house are overstepped by the Cornbrash before they reach Oxfordshire, 

where E. marmorea does not occur, and that therefore the Wychwood Beds 

of Oxfordshire are equivalent to the lower part of the Forest Marble of this 

district, as Buckman suggested. 1 However, for the present there seem 

insufficient grounds for complicating the nomenclature by retaining more 

than one designation for the Forest Marble, and Wychwood Beds is open to 

the fewest objections. 2 

That there is considerable overstep of the Great Oolite by the Forest 

Marble, at least over the Mendip Axis, seems probable from the occurrence of 

many derived ooliths and pebbles of oolitic limestone in the Forest Marble 

limestones. Moreover, in the Cotswolds the Forest Marble is often seen to 

rest, without the intervention of any Bradford Clay, upon an irregular and 

channelled surface of the Great Oolite. Such a junction was well displayed 

in the Stow-Road railway-cutting, between Chedworth and Cirencester, 

where it was remarked on and figured by Richardson. 3 Here, locally, the 

erosion has entirely removed the Kemble Beds, though they appear in the 

next cutting on the same line. Another particularly fine section is to be seen 

at Eastleach, where some Kemble Beds remain, with a deeply channelled 

upper surface. 

A complete section of the Forest Marble opened in the railway-cuttings 

between Alderton and Hullavington, on the South Wales line, was described 

by Woodward as follows: 4 

FOREST MARBLE AT ALDERTON 

[Cornbrash unconformable above.] 

Clays with thin layers of calcareous grit and a bed of Ostrea sowerby 

at top . . . . . . . . . 

Shales and limestones . . . . . . 

Sands and hard calcareous sandstones [Hinton Sands] . 

Oolitic and shelly and gritty limestones with lignite, and shales, false 

bedded, replacing one another [the main limestone block] 

Blue clay with occasional bands of limestone . . . . 

Total 

[Pale oolite below, seen to 18 ft.] 

Bradford Beds, or Bradford Clay and Acton Turville Beds. 

The fame of the Bradford Clay is due, not to any considerable thickness, 

but to its extraordinarily rich and constant fauna. Although the fauna is 

found only intermittently at the base of the Forest Marble, often being absent 

over considerable areas, it recurs repeatedly at the same horizon from Buckland 

Denham, close to the Mendips, to the eastern border of Oxfordshire, 

at Islip, and it was met with in the deep boring at Swindon. In most of the 

places where the fauna occurs, the bottom of the Forest Marble consists of 

a clay, which, in the typical area around Bradford-on-Avon, is about 10 ft. 

thick; but it does not follow that wherever a clay is present the fauna will be 

found also. 

1 See previous page, footnote 2. 

2 W. J. Arkell, 1931, Q.J.G.S., vol. lxxxvii, pp. 563-629, for full discussion. 

3 L.Richardson, 1911, P.G.A., vol. xxii, pp. 96, 103-4, pi. xv, xvi. 

4 H. B. Woodward, 1902, Sum. Prog. Geol. Surv. for 1901, pp. 59-60. 

ft. 

20 

5 

20 

3S-5o 

25 

105-120


The Bradford Clay assemblage comprises colonies of the brachiopods 

Ornithella digona (Sow.), Dictyothyris coarctata (Park.), Eudesia cardium 

(Lamk.), Epithyris bathonica Buck., Avonothyris bradfordensis (Dav.), A. langtonensis 

(Dav.), Rhytichonella obsoleta Dav., Kutchirhynchia morieri (Dav.), 

and numerous small Rhynchonellids not yet systematically studied. With them 

are associated Cidaris bradfordensis W r r., abundant Oxytoma costata (Sow.), 

and sometimes complete specimens of the crinoid Apiocrinus parkinsoni. The 

assemblage grew at Bradford-on-Avon in clear water, rooted upon an eroded 

surface of the underlying Great Oolite, and it appears to have been choked 

and killed by an influx of mud, which laid the crinoids undisturbed fulllength 

on the sea-floor amongst the brachiopods. Subsequently there was a 

pause long enough for all the shells and crinoids to become encrusted with 

Polyzoa and Serpulce. 

In one of the principal quarries at Bradford-on-Avon, between the Upper 

Westwood road and the tithe barn, the Bradford Clay can be seen to pass 

laterally into flaggy, false-bedded, typical Forest Marble, with the shells still 

abounding in the basal layers, but for the most part broken. 

The fossiliferous Bradford Clay has been detected in a boring at Buckland 

Denham, north-west of Biddestone, near Yatton Keynell, at West Keynton, 

Tiltups End near Nailsworth (in the form of a marl full of Rhynchonella 

obsoleta encrusted with Serpulce and Polyzoa), at Tetbury Road Railway Station 

near Kemble, at Ewen, and at Cirencester College. The close similarity of the 

faunas at these places renders the bed one of the most useful datum-lines in 

making correlations. 1 At Cirencester it yielded a unique ammonite, the only 

specimen of Clydoniceras found in England between the Cornbrash and the 

Stonesfield Slate—the type specimen of Clydoniceras hollandi {J. Buckman). 2 

It is not always that the fauna of the Bradford Clay is confined to so thin 

a seam and is divided by so sharp a boundary from the Great Oolite. In 

Normandy the fauna is spread through a very considerable thickness of rock— 

clays, marls, and limestones like our Great Oolite (the Pierre de Taille de Ranville 

and the second Caillasse). 3 Similar conditions recur in the South Cotswolds, 

between Marshfield and Corsham in the south and Malmesbury and 

the Wotton under Edge district in the north. Passing north from Bradfordon-Avon, 

the first signs of the change have been noted by H. B. Woodward 

at Yatton Keynell; he stated that 'The upper beds of the Great Oolite here 

contain many of the characteristic Bradfordian fossils, and show the intimate 

connexion between the Great Oolite and Forest Marble'. Again of a section at 

West Keynton he remarked: Tt is noticeable that pale false-bedded and fissile 

oolites, resembling beds of Great Oolite, occur above the fossiliferous Bradford 

Clay at this locality. Stratigraphically there is no real break in the series.' 4 

A complete section of these interesting beds was opened up in the 

approach cutting at the east end of the Sodbury Tunnel, near Acton Turville, 

1 S. S. Buckman stated that the Bradford Clay of Tetbury Road Railway Station was 

earlier, at least in part, than that of Bradford-on-Avon, but he published no reasons. T.A.y 

vol. v, 1924, p. 28. 

2 S. S. Buckman assigned it to a different genus, Harpoceratidarum\ see full discussion, 

T.A., vol. v, 1924, pp. 25-9; but if it is to be considered generically distinct, there will have to 

be at least half a dozen 'genera' made for the Cornbrash forms. 

* W. J. Arkell, 1930yP.G.A.y vol.xli, pp. 403-5. 

4 H. B. Woodward, 1 8 9 4 , p p . 268, 270.


during the construction of the South Wales line. Fortunately it was described 

in detail by Reynolds and Vaughan, who collected the fossils bed by bed, and 

thus a full record of this unique section is preserved. Resting on fine-grained, 

white, poorly-fossiliferous limestones (PKemble Beds), were no less than 

45 ft. of massive, wedge-bedded limestones, with lenticular seams of sandy 

clay, the whole abounding in the fossils of the Bradford Clay—Ornithella 

digona, Rhynchonella obsoleta, Eudesia cardium, Avonothyris aff. bradfordensis, 

Epithyris bathonica, Cidaris bradfordensis, with Oxytoma costatay Lima cardiiformisy 

Terebellaria ramosissima and the other characteristic Polyzoa of 

Bradford-on-Avon. Above came thick shales or clays with bands of limestone, 

indistinguishable from Forest Marble, but still with the Bradfordian fauna 

abundant towards the base. 

In collecting fossils from these remarkable beds, Messrs. Reynolds and 

Vaughan noticed an increasing resemblance to the assemblage at Bradfordon-Avon 

from below upwards. Although they grouped the strata on lithological 

grounds with the Great Oolite, they remarked that, except for their 

having failed to find either Dictyothyris coarctata or Apiocrinus 'it would be 

utterly impossible to separate the beds . . . from the Bradford Clay on palaeontological 

grounds . . . the uppermost beds are homotaxial with the clay at 

Bradford-on-Avon'. 1 To these strata Buckman later gave the name Acton 

Turville Beds. 2 It is possible that the lower portions of the 45-50 ft. of strata 

containing the Bradfordian fauna may be somewhat older than the fossil-bed at 

Bradford-on-Avon. On the other hand, the Bradford fossil-bed was obviously 

accumulated and covered with sediment very slowly, and it is probable that 

the more rapidly accumulated strata in the South Cotswolds were laid down 

during the same secule. If that is so, the name Acton Turville Beds is synonymous 

with Bradford Beds; but it may perhaps be usefully retained to distinguish 

the different facies. 3 

The Great Oolite Limestones. 

The detailed succession of the Great Oolite limestones changes so completely 

from place to place, and the stratigraphy and palaeontology have as yet 

received so little close study, that it is not practicable to give an ideal sequence, 

which might be recognizable throughout the Cotswolds. Certain broad 

correlations seem highly probable, but they are by no means certainly established. 

It is therefore necessary to give a brief resume of the succession first in 

the Bath district (the South Cotswolds) and then in the Minchinhampton, 

Cirencester and Chedworth district (Mid- and North Cotswolds). 

(a) THE BATH DISTRICT 

PKemble Beds, with Coral Bed, 12-20 ft. 

At Bradford-on-Avon the Bradford Clay rests upon 12-20 ft. of massive, 

obliquely-bedded to false-bedded and flaggy white or cream oolite, the lowest 

1 S. H. Reynolds and A. Vaughan, 1902, Q.J.G.Svol. lviii, pp. 742-6. 


3 The observation that the Acton Turville Beds became palaeontologically more like Great 

Oolite downwards and more like Bradford Clay upwards seems to have been mainly based on 

the brachiopod recorded as 'Terebratula maxillata . Owing to many previous misleading 

records, this was thought to be a Great Oolite species—what is now called E. oxonica. But in 

reality the species is E. bathonica, which is common in the Bradford Clay. (Teste Mr. L. 

Richardson, who saw some of the specimens.)


5-10 ft. of which are known as the Coral Bed. The corals are drifted, and 

when weathered out they leave ramifying caverns. They include C alamophyllia 

(Eunomia) radiata, Anabacia complanata, Convexastrcea waltoni, 

Isastrcea limit at a, Microsolena excelsa, Montlivaltia caryophyllata, Oroseris 

slatteri, Stylina plotii, and Thamnastrcea} With them are sponges and, somewhat 

rarely, Epithyris oxonica. 

? White Limestone: Ancliff Fossil Bed (15 ft.), and Upper Rag Beds 

(0-8 ft.). 

Below the Coral Bed is the highly fossiliferous oolite of Ancliff (Avoncliff, 

near Upper Westwood, west of Bradford-on-Avon), from which Sowerby 

received from local collectors many of the minutest fossils figured in the 

Mineral Conchology. It is a thin-bedded, coarse oolite, which is readily 

recognized by the abundance of shell-fragments and minute specimens of 

lamellibranchs and gastropods. The adults of the same species are found elsewhere, 

and the accumulation of juvenile individuals may be ascribed to the 

sorting action of currents. Among the types in the Sowerby collection 

obtained from this bed at Ancliff are those of Nucula variabilis, Nuculana 

lachrymay N. mucronata (a rubbed shell of the same), Parallelodon rudis, 

Navicula (Eonavicula) minuta, Barbatia pulchray Limopsis minima, Trigonia 

pullus, &c. The gastropods include Cerithium costigerum, Exelissa formosa, 

Rissoina acuta, R. duplicatay Turbo burtonensis and Solarium turbiniformis. 

At Monkton Farleigh, farther south, towards the Mendip Axis, the Ancliff 

Fossil Bed is only 2 ft. thick and is more or less blended with the Coral Bed. 

The Fossil Bed at Monkton Farleigh rests directly on the Bath Freestone, 

but in the Bradford-on-Avon district, in the large quarries at Avoncliff, 

Murhill (Murrel), &c., it is separated from the freestone by 3-8 ft. of poor 

quality oolite known as the Rag. Part of this usually forms the roof-bed of 

the stone mines. 

Bath Freestone, 8-30 ft. 

The Bath Freestone is an even-grained, poorly fossiliferous, fine oolite, 

which is still extensively mined in the district south-west of Corsham. Its 

excellent qualities are said to have been first generally realized when it had to 

be pierced for the Box Tunnel. Previously the demand had been only local, 

but after the coming of the railway Bath Stone soon began to be sent to all 

parts of the country, wherever a smooth, white freestone was in request. 

The freestone is reached by inclined shafts as much as 70-100 ft. deep, 

driven through the Forest Marble and Kemble Beds, and the galleries ramify 

for miles underground. Here, on the windy plateau, amid the stacks of huge 

blocks and the clink of chisels, it is easy to understand why William Smith 

used the term Great or Bath Oolite. Indeed, the name is peculiarly appropriate 

from here all through the South Cotswolds, to Minchinhampton and 

Stroud. As in all good freestones, fossils are scarce and small, and there seem 

to be none of any value for correlation. 

Lower Rag Beds, 10-40 ft. 

Under the freestone is a variable thickness of shelly and marly limestones, 

passing down into fissile oolite, with occasional bands of coral, known as the 

1 R. F. Tomes, 1885, QJ.G.S., vol. xli, pp. 174, 189.


Lower Rag Beds. Exposures are nowadays extremely rare, and little or nothing 

is known of them palaeontologically. H. B. Woodward records 4 Ammonites 

subcontr actus* in the basal bed near Charlcombe, Bath, but unfortunately 

the section in which he mentions it is a composite one. 1 Farther north, along 

the escarpment, quarries at Tolldown near Dyrham and near Tormarton 

show that the base of the Great Oolite, directly above the Stonesfield Slate 

Beds, consists of false-bedded, shelly white oolite suggestive of the Taynton 

Stone or the Ragstone Beds of the Stonesfield Slate about Northleach. 2 

Kemble Beds, 10-30 ft. 

(b) THE MID- AND NORTH COTSWOLDS 

Underneath the Bradford Clay with its rich fossil-bed at Tetbury Road Railway 

Station, north of Kemble, are exposed to the base of the quarry and railwaycutting 

10 ft. of massive, false-bedded, buff-coloured, oolitic, detrital limestones. 

The downward relations of the same beds are displayed north-west 

of Kemble, in a long cutting on the Tetbury branch line. These are the 

Kemble Beds of H. B. Woodward and subsequent writers, and they rest upon 

an evenly planed surface of White Limestone. In the type-locality they are 

about 30 ft. in thickness and are well exposed in the railway-cuttings north, 

north-west and south of the town. In the southern cuttings the junction with 

the Forest Marble clay is exposed for upwards of half a mile, the clay there 

being about 20 ft. thick but not yielding the Bradfordian fauna. 

In these cuttings there is displayed, rather below the middle of the Kemble 

Beds, an irregular fossil-bed crowded with Lima cardiiformis, Epithyris 

oxonica, Ostrea sowerbyi, and many other lamellibranchs, with corals of the 

genera Thamnastrcea, Isastrcea, Cladophyllia, and Cyathophora. The bed 

varies in thickness from 2 ft. to 10 ft. 3 

These beds (with which those in a corresponding position under the Bradford 

Clay around Bradford-on-Avon agree well enough) have a wide extension 

all over the Cotswolds. They are exposed at numerous places, showing below 

the Bradford fossil-bed at Tiltups End near Nailsworth, and at Ewen, and in 

force around Tetbury and Cirencester. Eastward they become more flaggy 

and assume a facies indistinguishable from Forest Marble. In this facies they 

spread all over the Cotswolds between Cirencester and the Oxfordshire 

border and have been mapped as Forest Marble. The change of facies even 

deceived H. B. Woodward, who wrote that 'The Kemble Beds evidently 

become thinner when traced from Kemble to Cirencester; while onwards in 

a north-easterly direction they become overlapped, near Baunton Downs, by 

the Forest Marble, which then rests directly on the White Limestone\ 4 

However, the conclusion that this was no overlap but a lateral change of facies 

was arrived at by Richardson in Gloucestershire and by the writer in Oxfordshire 

simultaneously and independently, and it is confirmed by the Oxfordshire 

section shortly to be described, where the Forest Marble facies of the 

Kemble Beds is succeeded by the Bradford fossil-bed. 

1 H. B. Woodward, 1894, J-R.B., p. 266. 

2 L. Richardson and W. J. Arkell, field-notes. 

3 H. B. Woodward, 1894,^.5., pp. 273-5 ; and W. J. Arkell, 1931, Q J.G.5., vol. lxxxvii, 

pi. LI and field-notes. 

4 H. B. Woodward, 1894, J.R.B., p. 285.

i9o 

White Limestone, 40-?60 ft. 

LOWER OOLITES 

The White Limestone is the most variable of all the members of the Great 

Oolite. The division comprises two principal types of rock: white, buff, or 

pinkish limestones, in which ooliths are often rare or absent, alternating with 

pale marls; and intensely hard, splintery, sublithographic limestone, often 

riddled with ramifying cavities. The sublithographic rock is known as Dagham 

Stone (after Dagham or Daglingworth Downs, near Cirencester, where 

it occurred at the surface and was quarried for rustic work and rockeries). 

Bands occur at several horizons in the series, but the principal development 

is generally at or near the top. In the railway-cuttings between Cirencester and 

Chedworth there are three bands, the highest and lowest 40 ft. apart. The 

majority of the cavities are probably due to the solution of branching corals 

Besides this there are often bands of corals which have not bee® dissolved 

away, the best known being that at Fairford, which had yielded some of the 

best-preserved fossil corals in the country—Isastrcea, Thamnastrcea, Thecosmilia, 

Stylina, Montlivaltia, Microsolena, Cryptocoenia, and Bathyccenia. 

Most of the specimens were obtained from a ploughed field and special 

excavations some miles north-west of the town, at Honeycomb Leaze, in the 

neighbourhood of which some quarries still show traces of the bed. The 

Fairford Coral Bed is traceable as a definite horizon near the top of the White 

Limestone into Oxfordshire, having been exposed at Milton under Wychwood 

and Burford as well as around Kemble. Nerinea eudesii Mor. and Lyc. is 

generally abundant in association with the corals. 

Another type of bed characteristic of the White Limestone is a lenticular 

band of marl crowded with brachiopods. The commonest species is Epithyris 

oxonica, which is confined to the upper part of the division. There are, however, 

a number of other smaller Terebratulids (Stiphrothyris and Cererithyris}) 

which still remain to be studied. The most interesting of these brachiopod 

marls are exposed in the fine railway-cuttings at Stony Furlong and Aldgrove, 

near Chedworth. Here Richardson detected and described an Ornithella 

Marl, 10 ft. thick, with abundant Ornithella digonoides S. Buck, and O. cf. 

minor (Martin), superficially indistinguishable from O. obovata and its many 

varieties from the Cornbrash. At a higher level in another cutting on the same 

line he found a marl with Burmirhynchia hopkinsi (Dav.), and lower down a 

limestone full of the calcareous alga, Solenopora jurassica, which retains its 

original red coloration and is known in consequence as 'beetroot stone'. 1 The 

marl with Ornithellids has also been found above the Fairford Coral Bed by 

Richardson. 2 

Beds crowded with gastropods are another characteristic feature of the White 

Limestone: Nerinea eudesii frequently forms Nerinea beds, usually in association 

with corals; Ptygmatis (Bactroptyxis) bacillus (d'Orb.) abounds below the 

Ornithella Marl at Aldgrove cutting; a 4 Nerinea bed' near Condicote is 

formed of myriads of Aphanoptyxis ardleyensis Ark., while another at Leach 

Bridge near Aldsworth is composed of A. bladonensis Ark. 3 

It was apparently from the lower part of the White Limestone (the equivalent 

of the Ancliff Fossil Bed) that Morris and Lycett obtained at Minchin- 

1 L. Richardson, 1911, P.G.A., vol. xxii, pp. 103, 110. 

2 L. Richardson, 1933, 'Geol. Cirencester', Mem. Geol. Surv. 

3 W. J. Arkell, 1931, Q.J.G.S.y vol.lxxxvii, pp. 615-22 and pis. LXIX, L.


hampton a large proportion of the beautifully preserved mollusca illustrated 

in their monograph. One of the principal sources of the specimens was 

8-15 ft. of wedge-bedded, shelly white oolite, called the 'Planking', underlying 

a coral bed. At the base of the Planking the gastropod genus Purpuroidea 

makes its first appearance. 

Two fossils which cannot be passed over in describing the White Limestone 

are Reptilian eggs (of Teleosaurus ?) found at the Hare Bushes Quarry, 

north-east of Cirencester, by James Buckman, and now in the British Museum 

and the ponderous lamellibranch, Pachyrisma grande Mor. and Lyc., which 

has been found in abundance, but in only two localities, Bussage and Chalford, 

south-east of Stroud. 2 

The base of the White Limestone, finally, has yielded some of the few 

ammonites of which the exact horizons are known. From a level at or near 

the base \ mile west-north-west of Salperton Church, in the Cotswolds, came 

a specimen identified by Buckman as Tulophorites tulotus Buck, (a species 

found in the Fuller's Earth Rock at Troll). 3 Similarly from the White Limestone 

(if not higher) must have come a unique specimen of Bullatimorphites 

bidlatimorphus Buck, found at Tiltups Inn, south of Nailsworth, 4 since the 

quarry there now exposes Forest Marble, Bradford Clay and Kemble Beds, 

and is unlikely to have been formerly worked very much deeper. In view of 

these and two Oxfordshire records, it seems probable that it was the Planking 

at Minchinhampton that in the past yielded most of the fairly numerous 

ammonites collected there, and not the Shelly Beds or Weatherstones lower 

down, as sometimes assumed. From Minchinhampton came the types of 

Tulites subcontractus (Mor. and Lyc.), Morrisiceras morrisi (Oppel), Madarites 

madarus Buck., Oxycerites waterhousei (Mor. and Lyc.) and Suspensites 

suspensus Buck., 5 but unfortunately Morris and Lycett paid no attention to 

the exact horizons from which they came and the large quarries have long 

since been abandoned. 

Hampen Marly Beds, 0-30 ft. 

In the North Cotswolds the White Limestone rests upon 20-30 ft. of grey 

marls with soft bands of earthy, marly limestone, characterized by beds 

crowded with large specimens of Ostrea sowerbyi and the typical form of 

Rhynchonella concinna (Sow.). The type-section is the Hampen cutting, near 

Salperton, on the Cheltenham-Banbury railway, described by Woodward and 

in greater detail by Richardson. 6 Here 28 ft. of the marls are exposed, overlain 

by 36 ft. of White Limestone and underlain by the Taynton Stone (30 ft.) 

(see fig. 49). The boundaries, both above and below, are quite distinct, and 

the division can be recognized at many places to the north and east as far as 

eastern Oxfordshire. Towards the south-west, however, the beds seem to die 

out or pass laterally into limestones, losing their distinctive fossils. Only 

1 J. Buckman, i860, Q.J.G.S., vol. xvi, pp. 107-10. 

2 H.B.Woodward, 1 8 9 4 , p . 280. 

3 L. Richardson, 1929, 'Geol. Moreton in Marsh', Mem. Geol. Surv., p. 119. 

4 J. Lycett, 1863, Mon. Moll. Great Oolite, Supplt., pp. 3-4 and pi. xxxi, fig. 1; also Buckman, 

T.A., pi. CCLXXII. 

5 See S. S. Buckman, 1921, T.A., vol. iii, pp. 43-52 and pis. DV, CDLXXVI, CCCXLVI, CCLXX, 

CCLXVIII A, CCLXXI—CCLXXIII, for discussion and figures of Minchinhampton ammonites. 

6 H. B. Woodward, 1894*J>R.B., p. 292; L. Richardson, 1929, 'Geol. Moreton in Marsh', 

p. 104, Mem. Geol. Surv. 

854371 V


6 miles away in this direction, in the complete section afforded by the Stony 

Furlong cutting south of Chedworth, the White Limestone would appear 

to have expanded to nearly 80 ft. and there is scarcely anything that can be 

correlated with the Hampen Marly Beds. There are a few feet of marls and 

WHITE 

LIMESTONE^ 

36' seen 

H A M P E N 

M A R L Y < 

BEDS 28' 

T A Y N T O N 

STONED 

30' 

STONESFIELD 

SLATE BEDS { 

FULLER'S 

EARTH^ 

IO' seen! 

EPITH yR!5 OXONICA cc3is. 

NERINEA. ere 

aLLayer of ANABACIA COMPLANATA 

TINERINEA. corals, e!x. 

OSTREA SOWERBY I 

5^-GASTROPOD BED 

TRIGONIA FULLUSerc. 

OyêrBediO.SOWERByi 

3


numbers of small and broken shells, very difficult to identify. This stone was 

extensively worked as a freestone about Windrush. Barrington, Taynton, 

Burford and Swinbrook at least as early as the middle of the seventeenth 

century, and of it St. Paul's Cathedral was largely built. Woodward seems 

to have introduced the name Taynton Stone, but it was known to Plot and 

Hooke, in the time of Charles II, as the Burford Stone. At Hampen it rests on 

the Stonesfield Slate Series, but in most parts of Oxfordshire it overlaps that 

series and comes to rest on the local equivalents of part of the Fuller's Earth. 

The principal objective at the great quarries at Minchinhampton was likewise 

a freestone, which rests in some places upon a thin representative of the 

Stonesfield Slate Beds and in others directly upon Fuller's Earth. It was called 

by Morris and Lycett the Weatherstones and Shelly Beds, and its thickness is 

16-20 ft. 1 The stone is current-bedded and hard with shelly layers. The shells 

often constitute a considerable proportion of the whole mass and, being converted 

into crystalline calcium carbonate, enhance the good weathering 

qualities of the stone. 

That at least some of the ammonites found at Minchinhampton came out 

of these beds seems to be shown by a label on a specimen of Morrisiceras morrisi 

(Oppel) in the Lycett collection, reading 'Minchinhampton, base of Great 

Oolite'. 2 They certainly supplied a large proportion of the other mollusca, 

which seem therefore to be less comminuted here than farther north-east. 

Owing to the disappearance of the Hampen Marly Beds to the south-west, 

the Weatherstones and Shelly Beds at Minchinhampton are directly overlain 

by the White Limestone ('Planking'). It is tempting to correlate the 

freestones of Taynton and Minchinhampton with the Bath Freestone. There 

are still the 10-40 ft. of Lower Rag Beds under the Bath Freestone to account 

for, and a possible equivalent for these occurs in the North Cotswolds, around 

Northleach, where freestones and 'ragstones' are developed to a considerable 

thickness between the Taynton Stone and the true slate-bed of the Stonesfield 

Slate. 

The Stonesfield Slate Beds. 

With the Stonesfield Slate Beds we again reach a stratum that can confidently 

be followed as a constant datum throughout the Cotswold Hills, from 

south of Bath into Oxfordshire. Its lithological peculiarities and special fauna 

make it the most valuable guide for elucidating the stratigraphy. It everywhere 

divides the Great Oolite above from the Fuller's Earth below, and there 

is always an intimate blending of the base of the sandy slate series with the top 

of the Fuller's Earth Clay. 

The Stonesfield Slate Beds consist typically of thin sands and sandy limestones, 

often in the form of spheroidal doggers called 'pot-lids' or 'burs', 

some of which split under the weather into fissile roofing-tiles. The principal 

fossils are abundant Ostrea acuminata mixed with O. sowerbyi (small), the 

ammonite Gracilisphinctes gracilis (J. Buckman), and Trigonia impressa Sow. 

and crushed Rhynchonellids. 

1 J. Morris and J. Lycett, 1850, 'Mon. Mollusca Great Oolite', Pal. Soc., pp. 2-3, and 

J. Lycett, 1837, The Cotteswold Hills, pp. 93-4; and H. B.Woodward, 1894, J.R.B., pp. 278-9 

(beds 2 and 3). 

2 S. S. Buckman, 1921, T.A., vol. iii, p. 49.


The most southerly known occurrence of sandy strata assignable to the 

Stonesfield Slate Beds seems to be indicated by a record of William Smith's 

at Combe Grove Fuller's Earth Pit (now closed), presumably somewhere on 

the slopes of the Combe Hay valley, south of Bath. 1 Here he described 6 ft. 

of 'sand and burs' separating the shelly Lower Rag Beds of the Great Oolite 

from the Upper Fuller's Earth (seen to 23 ft. 9 in.). No fossils were recorded, 

nor were any seen in sections near Tormarton, opened in 1931 during the 

laying of a water main. These showed grey, flaggy, sandy limestones, 5 ft. 

thick, between the white oolites like Taynton Stone and the Fuller's Earth 

Clay (seen to 25 ft.). 2 

Two miles north of this is the Sodbury Tunnel, where Reynolds and 

Vaughan record 36 ft. of compact sandy limestones, with thin clays, passing 

eastward into clays with subordinate hard, sandy limestones, and yielding the 

zonal index-fossil of the Stonesfield Slate, Gracilisphinctes gracilis. 3 Above 

were the usual coarse-grained oolitic limestones of the Great Oolite; below, 

the Fuller's Earth (90 ft. thick). The lateral passage from sandy limestones to 

clays corroborates the earlier writers, all of whom insisted upon the 'intimate 

blending' of the Stonesfield Slate Series with the Upper Fuller's Earth. 

The same alternation of bands of sandstones and clay, with abundant Ostrea 

acuminata, was recorded by Witchell in a trial shaft at Stroud. 4 Here the 

thickness was 15 ft., and of the Fuller's Earth below 55 ft. About Minchinhampton 

the Stonesfield Slates are sometimes absent and sometimes present, 

but they thicken in the country north-east of Stroud and become typical in 

both lithology and palaeontology. They were formerly worked for roofingslates 

about Througham near Bisley, where the series is 15 ft. thick. The main 

slate bed at the base, consisting of 2 ft. of fissile micaceous sandstone, contains 

Trigonia impressa, 5 the most characteristic fossil at Stonesfield and nowhere 

found at any other horizon. Slates were also worked in this district at Miserden, 

Nettlecomb near Birdlip, and at Rendcomb, 3 miles south-west of 

Chedworth. Thus they occur in workable development on each side of and 

over the Birdlip Axis of Inferior Oolite times. 

A few miles farther north-east, in the North Cotswolds, the Stonesfield 

Slate Beds attain their maximum development and are still worked in several 

places under the name of Cotswold Slates. The principal pits—open workings 

—are at Eyford Hill, Summerhill and Kineton Thorns, between Naunton and 

Condicote. The activity of the industry in the past may be judged by the fact 

that at Kineton Thorns alone no less than 120,000 slates were made in one 

season. Formerly workings also extended much farther west, to Salperton 

Downs and Sevenhampton Common, on the Cleeve Hill outlier above 

Cheltenham. 

The whole of this area has been carefully revised by Richardson, who has 

established the relations of the various types of rock to one another, to the 

Taynton Stone above and the Fuller's Earth below. As a type-section 

the Hampen railway-cutting is again useful (fig. 49). The total thickness of 

the Stonesfield Slate Beds is here 26 ft., constituted as follows: 

1 Printed in Phillips's Memoirs of W. Smith, 1844, p. 60. 

2 L. Richardson and W. J. Arkell,'field-notes. 

3 S. H. Reynolds and A. Vaughan, 1902, Q.J.G.S., vol. Iviii, pp. 739-41. 

4 E. Witchell, 1882, Geology of Stroud, p. 69. 

5 H. B. Woodward, 1894, jf.tf.tf., p. 281.

STONESFIELD SLATE: COTSWOLDS 279 

STONESFIELD SLATE BEDS OF HAMPEN CUTTING AND DISTRICT1 [Taynton Stone above, 30 ft.] 

Sevenhampton Rhynchonella Bed: yellowish marl with Kallirhynchia spp. ft. in. 

(as in the marl below) and Stiphrothyris sp. At Sevenhampton this bed 

also contains corals, Isastrcea and Anabacia, O. acuminata, O. sowerbyi, 

&c. . . . . . . . . . . . . 1 o 

Acuminata-Sowerbyi Bed: limestone crowded with oysters 

1 o 

Sevenhampton Marl. At Sevenhampton this comprises 4J-6 ft. of sandy 

indurated marl, with O. acuminata and many Rhynchonellids—R. 

obtusa, R. decora, R. communalis, R. deliciosa, &c. At Hampen it is only . 

Ragstone Beds: Limestones, mostly fine-grained and compact, sparsely 

oolitic, locally fissile, locally shelly and coarsely oolitic, with 9 in. band of 

soft-weathering sandstone towards the bottom . . . . 

Slate Beds: bluish paper-shales with fissile sandy layers 

Yellow sand, with 6 in. band of fissile sandy limestone at top . 

Hard, blue-hearted, slightly sandy limestone with claystone inclusions, 

O. acuminata and a few other fossils . . . . . . 

[Fuller's Earth below, consisting of bluish paper-shales with layers of 

hard grey marl and occasional thin seams of fissile sandy stone; seen 

to 10 ft.] 

The Sevenhampton Rhynchonella Bed and the Acuminata-Sowerbyi Bed 2 

are very persistent over the North Cotswolds and form a useful index for distinguishing 

the Taynton Stone above from the Ragstones of the Stonesfield 

Slate below; and in the country around Northleach Richardson has shown 

that these two stones become extremely similar. 3 At Fosse Quarry, Farmington, 

for instance, a 20 ft.-face of limestones and freestone closely resembling 

Taynton Stone is exposed, but he shows that the Acuminata-Sowerbyi 

Bed at the top indicates that it is the Ragstone Beds in a freestone facies. 

These beds may well correspond with the Lower Rag Beds beneath the Bath 

Freestone. 

The fauna of the actual slate beds is very rich and characteristic, leaving no 

room for doubt that the slates are on the same horizon as those at Stonesfield. 

On the surfaces of the split slabs of fissile, sandy oolite may be seen abundant 

Trigonia impressa and Placunopsis socialis, while from the slatters have been 

obtained Gracilisphinctes gracilis, 4 Micromphalites oxus S. Buck., 4 and remains 

of pterodactyles (Rhamphocephalus prestwichi Seeley), deinosaurs (Megalosaurus 

sp.), crocodiles (Steneosaurus and Teleosaurus), fish (Lepidotus, Mesodony 

Hybodus, Ischyodus, Strophodus), belemnites (Belemnopsis bessina d'Orb. sp. 

and B. aripistillum Lhwyd sp.) and other mollusca, a cirripede, a starfish, an 

annelid, insects, and plants. 5 

Eastward, before reaching the edge of the Vale of Bourton, the Stonesfield 

Slate Beds die out, being overlapped by the Taynton Stone (as in Roundhill 

1 Condensed from L. Richardson, 1929, 'Geol. More ton in Marsh', Mem. Geol. Surv.y 

pp. 102-16 with references to all previous literature. 

2 This has usually been called the Acuminata Limestone, but it is important to keep it 

distinct from the pure Acuminata Bed at a lower level farther south. 

3 L. Richardson, 1933, 'Geol. Cirencester', Mem. Geol. Surv. 

4 Figured S. S. Buckman, T.A., pi. cxcm, DCXLIV. 

5 For more complete list, and references,see Richardson, 1929, 'Geol.Moreton in Marsh*, 

p. 114. 

12 

6 

1 

26


railway-cutting) so that Taynton Stone rests directly on Fuller's Earth; or 

remaining very thin and yielding no characteristic fossils or workable slates 

(as at Oddington near Stow on the Wold). 

The Fuller's Earth (with Upper Estuarine Clay and Chipping Norton 

Limestone). 

The Fuller's Earth of commerce is still mined above the village of Combe 

Hay, south of Bath, the method being to drive adits into the steep hill-side. 

Formerly there were pits at Wellow, Midford, South Stoke, Combe Monkton, 

Lyncombe, Widcombe, and elsewhere. The commercial product is a soft, 

grey, slightly greasy clay, with a bluish or greenish tinge when fresh, but 

weathering buff or brown. It contains slight quantities of lime, iron, 

magnesium, sodium and potassium, but its fulling qualities are due to its 

peculiar physical properties, one of which is disintegration in water. The 

commercial Fuller's Earth occurs only in the Upper Fuller's Earth Clay. 1 

The complete succession of the formation between the Mendip Axis and 

Bath may be pieced together from a number of records. The Lower Rag Beds 

below the Bath Freestone (resembling Taynton Stone or the Ragstone Beds 

of the Stonesfield Slate Beds) may be seen well exposed in the hill-side about 

12-15 ft. above the entrance of the present working mine. We know from 

William Smith's record at Combe Grove Pit (already quoted) that, at least 

locally, up to 6 ft. of sands with 'potlids' assignable to the Stonesfield Slate 

intervene between the Great Oolite and the Upper Fuller's Earth, and that 

the workable seam of Earth occurs there 11 ft. below the sands. It is itself 

5 ft. thick and rests upon a 2-ft. band of stone, with more marls below. At 

Midford Woodward recorded 17J ft. of clays above the workable Earth, 

which there also is 5 ft. thick. 2 

The Hemington boring tells us that the Upper Fuller's Earth is more than 

32 ft., the Fuller's Earth Rock about 15 ft., and the Lower Fuller's Earth 40 ft. 

thick, while the wells about Bath show a total thickness of 70 ft., only slightly 

less than at Hemington. At Hemington the band packed with Ostrea acuminata 

was encountered immediately below the Fuller's Earth Rock, just as 

south of the Mendips; and although no fossils were recorded from the Rock 

itself in the boring, the exposures a few miles away, at Bonneyleigh Hill and 

Egford Bridges, show that it is highly fossiliferous, and the fossils are specifically 

identical with those in the Fuller's Earth Rock farther south, and form 

the same assemblage. Finally, the Lower Fuller's Earth is known in detail 

from the railway-cutting at Combe Hay, put on record by Richardson. 3 The 

cutting showed 35 ft. of Lower Fuller's Earth and the junction with the 

Inferior Oolite. By comparison with the Hemington boring, the top of the 

cutting must have reached within a few feet of the base of the Fuller's Earth 

Rock, a conclusion borne out by the fact that the highest level exposed was 

crowded with Ostrea acuminata. The 35 ft. of clay contained a few thin bands 

of limestone, but no real development of 'rock'. At the base Ostrea knorri 

was abundant, as at Doulting and in Dorset, and at the junction with the 

Inferior Oolite an indication of the Zigzag Bed was given by a large ammonite 

of the zigzag zone. 4 

1 H.B.Woodward, 1894, J.R.B., p. 242. 2 Ibid. 

3 L. Richardson, 1909, P.G.Avol. xxi, p. 426. 

4 Figured, S. S. Buckman, 1922, T.A., pi. CCCII*.

FULLER'S EARTH: COTSWOLDS 281 

There are some indications that westward the Fuller's Earth diminishes in 

thickness, just as it does west of the Westbury boring. Lycett estimated the 

total thickness penetrated in the Box Tunnel at 148 ft., an estimate which 

Woodward rejected on the ground that the wells at Bath do not prove more 

than 70 ft. but in the light of the Westbury boring, where 207^ ft. was 

proved, it appears quite possible. The discovery of typical Fuller's Earth 

Rock fossils (Stiphrothyris, Ornithella cadomensis, Rhynchonelloidea smithii, 

and Ostrea acuminata) in pockets in the Upper Inferior Oolite on Dundry 

Hill, and indeed not on the top of the Inferior Oolite but upon the Upper 

Coral Bed, suggests that the westward attenuation may involve an overlap of 

the Lower Fuller's Earth by the Fuller's Earth Rock. 2 A similar conclusion is 

suggested by a statement of Woodward's that he saw Fuller's Earth with 

4 Waldheimia ornithocephala [bathonica] resting on a bored surface of the 

Inferior Oolite' near Severcomb Farm. 3 Again at Dyrham, on the edge of the 

escarpment, where Richardson discovered the Fuller's Earth Rock crowded 

with brachiopods (Ornithella bathonica and O. pupa) as in Somerset, it can be 

seen to be not more than about 25 ft. above the Inferior Oolite. 

About 7 miles due east of Dyrham, Hull described the following section 

in a lane east of Slaughterford : 4 

ft- 

White marls with occasional stony bands . . . . . 25 

White and grey limestone and marlstone (Fuller's Earth Rock) . 10 

White and blue clays with Terebratula perovalis and T. maxillata 30 

Five miles north-east of Dyrham is the Sodbury Tunnel, where Reynolds 

and Vaughan estimated the thickness of the Fuller's Earth to be 90 ft. From 

their study of the materials brought up from the shafts and the records of 

strata, they concluded that 'when traced laterally, the lithological character 

is very inconstant, for the clays pass, on the one hand into shales, and on the 

other into beds of hard shelly marl. In the middle of the series, however, 

there are one or more beds of argillaceous limestone, which mark a fairly 

constant horizon'. Their generalized section is as follows : 5 

SUMMARY OF THE FULLER'S EARTH AT SODBURY TUNNEL 

[Stonesfield Slate with Gracilisphinctes gracilis above.] ft 

Clay and shale, full of Ostrea acuminata . . . . . 28 

Argillaceous limestone . . . about . . . . . . 10 

Clay with Ostrea acuminata . . . . . . . 27 

Compact blue limestone with [Stiphrothyris] and O. acuminata 5 

Shale 24 

[Oolitic limestone of Inferior Oolite below.] 

1 1894, J.R.B., p. 243. 

2 L. Richardson, 1907, Q.J.G.Svol. lxiii, pp. 421-2; and Reynolds and Vaughan, 1902, 

Q.J.G.S., vol. lviii, p. 740. 

3 H. B. Woodward, 1894,J.R.B.y p. 241. 

4 E. Hull, 1858, 'Geol. Parts of Wilts, and Gloucester', Mem. Geol. Surv., p. 12. 

5 S. H. Reynolds and A. Vaughan, 1902, Q.J.G.S., vol. lviii, pp. 739-41. 

65 

94


They also recorded Rhynchonell[J.R.B., pp. 244-5, with full references. 

3 Richardson and Arkell, field-notes. 

4 L. Richardson, 1929, 'Geol. Moreton in Marsh', Mem. Geol. Surv.y pp. 54, 75.

FULLER'S EARTH: COTSWOLDS 283 

Oxfordshire, and he calls it the Upper Estuarine Clay, for it closely resembles 

the clay at the base of the Upper Estuarine Series in Southern Northamptonshire, 

with which he has connected it by a chain of quarries. It is a highly 

important and easily recognized datum. 

Beyond the Guiting Valley, east of a line drawn N.-S. from Snowshill, 

through the Guitings to Notgrove, a new feature makes its appearance between 

the Upper Estuarine Clay and the Clypeus Grit—the Chipping Norton Limestone. 

1 It spreads over the hills in the North Cotswolds as far north as 

Snowshill and Bourton on the Hill, attaining a thickness of 20-25 ft., and continues 

as a surface-feature of considerable importance across Iccomb Hill into 

Oxfordshire. It was originally confused with and mapped as Great Oolite, 

but its true position has now been established by Richardson. 

The best section illustrating the succession in this eastern part of the North 

Cotswolds was formerly to be seen in Roundhill railway-cutting, about a mile 

south of Naunton. The following is a condensation of the section (now much 

obscured), amplified by 2 neighbouring quarry at Roundhill Farm: 2 

SECTION AT ROUNDHILL RAILWAY-CUTTING AND FARM 

[Taynton Stone above, seen to about 8 ft.] 

[Non-sequence: Stonesfield Slate overlapped.] 

ft. in. 

FULLER'S EARTH : clays and marls . . . . . . 20 o 

UPPER ESTUARINE CLAY (seen at Roundhill Farm Quarry): heavy clay, 

chocolate above, green in middle, black at base . . . . - 3 7 

PEBBLE-BED: brown marly layer with waterworn pebbles of hard brown 

oolite, encrusted by oysters, Serpulce and polyzoa . . . . 4 

CHIPPING NORTON LIMESTONE: obliquely laminated oolite, about . 12 o 

with at the base a seam of clay (Roundhill Clay) . . . . 1 6 

[Clypeus Grit below, seen to 5 ft. 9 in.] 

Here the Fuller's Earth, including the thin Upper Estuarine Clay at the base, 

is still 231 ft. thick; but towards the north-east, before reaching the Vale of 

Moreton, it is overlapped by the Taynton Stone, so that on the hills around 

Condicote the Great Oolite limestone (Taynton Stone) rests in places directly 

on the Chipping Norton Limestone (as at Stonehill Quarry, near Stow on the 

Wold). 3 Generally, however, a few feet of Fuller's Earth remain, comprising 

little else but the Upper Estuarine Clay, which in turn rests upon a waterworn 

surface of the Chipping Norton Limestone, with the pebble-bed at 

the junction. Many of the quarries in the Chipping Norton Limestone show 

this pebble-bed, with a few feet of Upper Estuarine Clay above, and in one or 

two places (especially Bolton's Ground Quarry, | mile south of Condicote 4 ) 

there is at the base of the Upper Estuarine Clay, mixed with the pebble-bed, 

up to 1 ft. 8 in. of pale greenish-grey fossiliferous marl. Richardson correlates 

this with a freshwater bed containing Viviparus in North Oxfordshire, to be 

described in the next section. 

1 So named by Hudleston in 1878. 



4 L. Richardson, 1929, loc. cit., p. 99.

i9O LOWER OOLITES 

Richardson's detailed field-work has therefore shown that in the North 

Cotswolds there are two discordances within the lower part of the Great 

Oolite Series. Towards the east the Taynton Stone overlaps or oversteps the 

whole or the greater part of the Fuller's Earth; towards the west the Upper 

Estuarine Clay oversteps the Chipping Norton Limestone on to Clypeus Grit. 

The significance of the latter overstep depends on the discovery of Oppelia 

fusca in the upper part of the Chipping Norton Limestone at several places in 

the North Cotswolds and at Oakham, near Chipping Norton; the limestone 

therefore belongs to the fusca and probably the zigzag zones and so is equivalent 

to the basal portion of the Fuller's Earth in the South Cotswolds and to 

the Crackment Limestone in the Sherborne District. Richardson has thus 

proved an overstep of the basal Fuller's Earth by the Upper Estuarine Clay— 

itself an horizon within the Lower Fuller's Earth. How far west and south 

this overstep continues is still unknown, for the Upper Estuarine Clay is still 

unidentified within the main mass of the Fuller's Earth in that direction. 

Towards the north-east, however, the Upper Estuarine Clay, as the base of 

the Upper Estuarine Series, remains a highly transgressive horizon throughout 

the eastern counties. 

This section must be concluded with a brief description of the Chipping 

Norton Limestone. 1 

The typical aspect of the rock is a brownish or white oolite, often blackspecked 

with tiny flecks of ground-up lignite, but otherwise difficult to distinguish 

from Great Oolite. In this facies it is best seen near Stow on the 

Wold and at Newpark Quarry, Longborough, where it has yielded vertebrae 

of Megalosaurusy Teleosaurus subulidens Phil, and Steneosaurus. 

Oblique lamination is frequent in the upper part, and local accentuation of 

this feature produces flaggy stone, which may become sandy and sufficiently 

fissile to be used as roofing slates or tilestones. The fissile, sandy facies is 

especially well developed in the north-west, towards Snowshill, where the 

slates have been extensively worked at Hyatt's Pits and used for roofing many 

of the buildings in the village. It is also developed south-west and south-east 

of Condicote, where old mines can be seen at Flagstone, midway between 

Condicote and Upper Swell. The slates are usually thick and heavy, but 

locally they are of better quality and may be virtually indistinguishable from 

the Stonesfield Slates quarried in the same area. 

The sandy element is especially marked in the west, near Temple Guiting, 

where, probably as a product of decalcification, layers of true sand are intercalated 

in the upper part of the limestone. Over a considerable area of the 

outcrop the soil resulting from the decomposition of the beds is so sandy as 

to be quite unlike the soil to which a limestone usually gives rise. Mr. J. G. A. 

Skerl has analysed samples of the sand and found it to contain upwards of 

70 per cent, of calcium carbonate, with smaller proportions of kyanite and 

sphene than are found in the sands at lower horizons. 

Some peculiar features in the Chipping Norton Limestone, especially 

marked at Guitinghill Quarries near Condicote, are lines of intensely hard 

calcareous lumps or 'Node beds' near the top, and a pebble bed about the 

centre of the series. The pebble-bed, 1 ft. thick, is a marl, crowded with 

Ostrea sowerbyi and some other fossils, especially the corals Isastrcea limitata 

1 See L. Richardson, 1929, loc. cit., pp. 86-98.

GREAT OOLITE SERIES: OXFORDSHIRE 385 

and Cyathophora pratti, Trigonia pullus, Lima cardiiformis, and gastropods. 

Few species besides these occur in the Chipping Norton Limestone of the 

Cotswolds, but, taken in conjunction with the vertebrate remains, they indicate 

much closer affinity with the Great Oolite proper than with the Inferior 

Oolite. 

At the base of the series, separating it from the Clypeus Grit, there is locally 

a thin band of clay named by Richardson the Roundhill Clay. Its greatest 

thickness is 6-20 in. 

IV. OXFORDSHIRE 

The behaviour of the Upper Inferior Oolite, with which the Great Oolite 

Series is usually conformable, has already prepared us for what is to be 

expected in the country east of the Cotswolds. So far as known, there is no 

thinning of the Great Oolite compensated by further thickening eastward over 

the Oxon. border and therefore directly attributable to the Vale of Moreton 

Axis. Instead there is a general, though irregular, easterly attenuation throughout 

Oxfordshire and into Northamptonshire. In order to trace the several 

stages of this attenuation, which is a complicated one, affecting nearly all the 

members of the series, it is necessary to describe as a separate province the 

county of Oxfordshire. It is only by following out every stratigraphical subdivision 

from the Cotswolds through Oxfordshire, noting the lateral changes 

and the disappearances of certain strata, that we can hope to arrive at a true 

correlation of the greatly modified and attenuated Great Oolite Series of the 

Northamptonshire to Lincolnshire area. 

A more convenient province for our purpose than that enclosed by the 

county boundary could scarcely be defined. It is divided into three parts by 

the valleys of the Evenlode and the Cherwell (see map, fig. 38, p. 207). The 

most westerly part is a triangular area south of the Evenlode, the base formed 

by the county boundary from Eastleach to the Iccomb hill-mass, the apex at 

Handborough. In the centre is the main bulk of the outcrop, the dissected 

plateau stretching from Woodstock past Chipping Norton and Hook Norton 

to Banbury and Epwell, in the extreme north of the county; the original 

resemblance of this plateau to that of the North Cotswolds has already been 

noticed in Chapter VIII. Finally, east of the Cherwell Valley lies another 

triangular area like the first, the apex at Enslow Bridge near Kirtlington, the 

base defined by the valley of the Ouse, from Buckingham to Brackley. 

Sections are plentiful in all three areas. In the south the quarries expose 

only the upper beds, the 'Forest Marble' and the upper part of the White 

Limestone. These strata may be studied in great detail, in vast excavations 

at the Oxford Portland Cement Works at Shipton-on-Cherwell and Kirtlington, 

and in numerous quarries at Bladon, Handborough, Witney, Asthall and 

over all the area south of Burford. Lower beds, especially the Taynton Stone 

and Chipping Norton Limestone, formerly much in demand for building, are 

exposed in the north of the county. The Stonesfield Slate cannot be seen 

anywhere in situ and all the old workings are abandoned. 

Within the area thus defined, the Great Oolite Series comprises the following 

subdivisions:


FOREST 

V. MARBLE 

W'YCHWOOD BEDS 

BRADFORD BEDS 

KEMBLE BEDS 

[Cornbrash above.] 

Stratal Divisions. 

FIMBRIATA-WALTONI BEDS 

(Green clays and fossiliferous greenish marls) 

GREAT ^ 

THE WHITE LIMESTONE 

OOLITE 

LIMESTONES HAMPEN MARLY BEDS 

sandy*^^^ 

TAYNTON STONE 

slate b e d s ^ ^ STONESFIELD SLATE BEDS 

ft. 

thickness. 

0-12 

10-20 

3-H 

| 20-30 

17-25 

10-25 

UPPER ESTUARINE CLAY O-3 

SHARP'S HILL [NE^RAN] BEDS 

CHIPPING 

NORTON 

SWERFORD BEDS and WHITE SANDS 

LIMESTONE HOOK NORTON BEDS 

[Clypeus Grit overlapped below.] 

SUMMARY OF THE GREAT OOLITE SERIES OF OXFORDSHIRE 1 

Wychwood Beds, 0-12 FT.L _ F FOREST MARBLE AND BRADFORD CLAY 

Bradford Beds, 0-7 ft. / ~~ L FARTHER S. AND W. 

0-6 

0-10 

10-25 

After an interval of about 16 miles from the Cirencester district, the fossilbed 

of the Bradford Clay reappears in the south-west corner of Oxfordshire, 

west of Carterton cross-roads, near Shilton. It consists of 1 ft. of argillaceous 

limestone, hard in the centre, but marly above and below, from which weather 

numerous examples of Ornithella digona and Rhynchonella obsoleta Dav., 

together with other Rhynchonellids and Dictyothyris coarctata (Park.). The 

fossil-bed lies in the centre of 6 ft. of buff to grey clay, with limestones of 

Forest Marble facies above and below. Thence north-eastward it has been 

described at three other places, Witney, Bladon and Islip, extending over 

a total distance of 17 miles. 

In the area of Wychwood Forest, where the Forest Marble acquired its 

name, there are now only a few shallow sections not overgrown, and the 

stratigraphical position of the rock quarried in William Smith's time as 

'marble', for fashioning into polished mantelpieces and door-jambs, is in some 

doubt. But by comparison with the quarries at Witney, on the southern outskirts 

of the forest, and with other quarries in the county, there seems little 

doubt that the actual 'marble' was obtained, not from the thin-bedded shaly 

limestones above the Bradford Clay, universally known as Forest Marble 

farther south, but from the Forest Marble facies of the Kemble Beds, below 

the horizon of the Bradford Clay. According to Plot the marble industry had 

1 Forest Marble to Taynton Stone based on W. J. Arkell, 1931, 'The Upper Great Oolite, 

&c. of South Oxfordshire', Q.J.G.S., vol. lxxxvii, pp. 563-629.

KEMBLE WITNEY HANDBOROUGH BLAD0N RIVER CHERWELL KIRTLINGTON ISLI P 

WYCHWOOD 

BEDS 

BRADFORD 

FOSSIL BED 

F. BEDS 

FIM BRIATA 

WALTON I 

BEDS 

MIDDLE EPI- 

THYRIS & 

PEBBLE BEDS 

LOWER EPi- 

TriYRIS BED 

NERINEA 

EUDESI! 

BEDS 

FIG. 50. Correlation of the upper part of the Great Oolite Series in the principal exposures in South Oxfordshire and at Kemble, Glos. 

(From W. J. Arkell, 1931, Q. J.G.S., vol. lxxxvii, pi. u.) Note:—Recent evidence supplied by new exposures shows that the strata at Bladon 

here correlated with the Fimbriata-waltoni Beds are more correctly classed with the Kemble Beds; see Arkell, I933> P.G.A., vol. xliv.


already begun nearly a century and a half earlier in the parish of Bletchington 

(presumably at the ancient Greenhill Quarries, near Enslow Bridge), where 

'a sort of Grey Marble' was made into chimney-pieces and pavements for 

Bletchington Park and Cornbury Park; it was also used, he tells us, in the 

pillars of the portico of St. John's College, as well as in the making of tombstones, 

tables, and millstones. 1 Here the only available rock is certainly a 

part of the Kemble Beds, as may be seen in the neighbouring quarry at Islip, 

where identical stone is succeeded by the Bradford Fossil Bed, which in turn 

lies only 4 ft. below the Cornbrash. 

Thus in and about Wychwood Forest the stratigraphical term Forest 

Marble, as used by William Smith and his successors for over 130 years, 

embraces both the strata between the Cornbrash and the Bradford Clay and 

the Kemble Beds; moreover, the rock to which the petrological term was 

formerly applied is part of the Kemble Beds. For this reason the name 

should be abolished and the strata between the Bradford Fossil Bed and the 

Cornbrash in future be called the Wychwood Beds (from Buckman's Wychwoodian, 

which was defined as post-Bradfordian). Detailed stratigraphical 

research, however, has not yet been carried far enough in Wilts., Somerset 

and Dorset to enable the name to be applied along the whole outcrop, and 

there the old term 'Forest Marble' has still to be retained. 

The Wychwood Beds in Oxfordshire are simply a continuation of those in 

Gloucestershire, comprising the same thin-bedded, flaggy, broken-shell limestones, 

with lignite, clay-galls, ripple-marks and worm-tracks, interspersed 

with greenish-grey shaly clay. The fauna consists almost entirely of lamellibranchs, 

especially Camptonectes laminatus and C. rigidus, Ostrea sowerbyi, 

&c., and locally Corbula islipensis Lyc., Gervillia islipensis Lyc., Cuspidaria 

ibbetsoni (Mor. & Lyc.), tests of Acrosalenia hemicidaroides, &c. The great 

reduction in the thickness of the beds as compared with Gloucestershire 

points to a north-eastward overstep by the Lower Cornbrash. Still farther 

north-east, in Buckinghamshire, Northants. and beyond, this overstep is 

continued, the Wychwood Beds and Bradford Beds being cut out altogether. 

Even in Oxfordshire there were several local uplifts and the Cornbrash sometimes 

rests directly on Kemble Beds. These places were mapped by E. Hull 

and described in a Survey Memoir in 1859. 2 One is at Handborough, another 

at Greenhill Quarries near Enslow Bridge, in the Cherwell Valley, while 

between them, at Bladon and Campsfield, the Wychwood Beds are 12 ft. thick. 

Kemble Beds, 10-20 ft. 

The Kemble Beds enter the county from Gloucestershire in their Forest 

Marble facies and cover the greater part of the triangle south of the Windrush 

to a thickness of about 20 ft., under Holwell and Alvescot Downs. There are 

some deep exposures in hard oolitic flags, and near Holwell a thick intercalated 

band of clay was formerly worked for brick-making. The best sections are in 

Crawley Road and Ducklington Lane Quarries, Witney, where the complete 

sequence may be seen. The Kemble Beds are 19 ft. thick and are overlain by 

the Bradford Fossil Bed, with Ornithella digona and the usual fossils, succeeded 

by 8 ft. of Wychwood Beds and then the Cornbrash (fig. 50). The bulk of the 

1 R. Plot, 1676, Natural History of Oxfordshire, p. 79. 

2 E. Hull, 1859, 'Geol. Woodstock', Mem. Geol. Surv., p. 24 and accompanying map; and 

Arkell, 1931, loc. cit., pp. 578, 586.

PLATE XIII 


Great Oolite Series at Kirtlington Cement Works, near Oxford. 

CB = Lower Cornbrash; WB = Wychwood Beds; KB = Kemble Beds; 

FW = Fimbriata-waltoni Beds (green clay); WL = The White Limestone. 


Chipping Norton Limestone-equivalents, Fritwell railway-cutting, Oxon. 

North side of cutting at east end of Fritwell Tunnel, showing black and white 

sands of the Swerford Beds, resting on a deeply channelled surface of the 

Hook Norton Beds. A channel is shown by the white lines.


Kemble Beds consists of massive, false-bedded, coarsely-oolitic, blue-hearted 

limestones, but near the top there is a 4 ft. lenticle of dark blue clay and at the 

base a 2 ft. 4 in. block of highly fossiliferous 'Cream Cheese' or sublithographic 

limestone, with a splintery fracture. The Cream Cheese Bed is the 

highest bed in Oxfordshire containing Epithyris oxonica in abundance, and it 

has therefore been called the Upper Epithyris Bed. With the brachiopods are 

masses of the branching corals Convexastrcea waltoni and Thamnastrcea 

lyelli, together with Stiphrothyris capillata, Lima cardiiformis and other fossils. 

An identical rock is found also at the base of the Kemble Beds farther east, at 

Shipton-on-Cherwell Cement Works near Enslow Bridge, at Kirtlington 

Cement Works, and at Blackthorn Hill railway-cutting near Bicester. 

At both Shipton-on-Cherwell and Kirtlington the Cream Cheese Bed 

(there 4 ft. thick), crowded with fossils, can be seen to pass laterally along the 

quarry face into the unfossiliferous, false-bedded, oolitic facies, and then at 

Shipton, by the intercalation of seams of clay and sandy oolite, into typical 

'Forest Marble'. At Greenhill Quarries, opposite the Shipton-on-Cherwell 

Cement Works, the Forest Marble facies is indistinguishable from Wychwood 

Beds, having all the clay-galls, ripple marks, sandy texture and the common 

facies-lamellibranchs. 

At Kirtlington (Plate XIII and fig. 51) the Cream Cheese Bed is overlain by 

ft. of grey-blue clay with three pale mudstone layers, into which the upper 

part of the unfossiliferous Kemble Beds is transformed by lateral passage. 

The only common fossil in the clay is Placunopsis socialis, which abounds. The 

same clay, with abundance of the little Placunopsis, overlies the limestones of 

the Kemble Beds at numerous places, such as Blackthorn Hill, Handborough, 

&c., while at others, such as Witney and Shipton-on-Cherwell, it occurs as 

a lenticle enclosed in the limestones. At Handborough, in the railway-cutting, 

the whole of the limestones are replaced by clay to a thickness of 14 ft., and 

the passage may be traced out in a continuous section. 1 

Pebbles and other signs of erosion have been seen at the base of the Kemble 

Beds at Handborough and Shipton-on-Cherwell. 

Fimbriata-Waltoni Beds, 3-9 ft. and in N. Oxon. over 13 ft. 

With great regularity all through the county, along at least 30 miles of 

outcrop, the Kemble Beds are underlain by green clays with argillaceous 

fossil-beds and lignite, which have at the base a thin bed of drifted, loose or 

crushed valves of Epithyris oxonica and Ostrea sowerbyi (the Middle Epithyris 

Bed) resting on an eroded surface of the underlying limestones, often with 

rolled and bored pebbles. These strata have been called after the two commonest 

fossils, Astarte fimbriata Lyc. and Gervillia waltoni Lyc., which often 

occur in myriads, together with abundant Protocardia subtrigona (Mor. and 

Lyc.), Corbula hulliana Mor., Aphanoptyxis bladonensis Ark. and other species. 

The fossils readily weather out of their argillaceous matrix and may be collected 

in a more perfect state of preservation than those from any other part of the 

Great Oolite Series. The seam of drifted Epithyrids and pebbles is also the 

place of sepulture of the huge bones of the land deinosaur, Ceteosaurus 

oxoniensis Phillips, which were found at Enslow Bridge, Bletchington Railway 

Station and Kirtlington Cement Works. Unfortunately the modern method of 

1 W. J. Arkell, 1931, loc. cit., p. 587. 

s:n:i7l X

WYCHWOOD 

BEDS 

WHITE 

LIMESTONE 

FIG. 51. Section of the upper part of the Great Oolite Series at Kirtlington Cement Works, near Oxford. Brachiopod facies shown thus + 

(Horizontal scale much compressed.) (From W. J. Arkell, 1931, QJ.G.S., vol. lxxxvii, p. 571-)


working, by blasting and steam excavators, precludes the recovery of any more 

bones, and doubtless many skeletons have already been turned into cement. 

As we have seen, the fauna of the Fimbriata-waltoni Beds is found in 

Gloucestershire in the top of the White Limestone, and it seems that there 

is a lateral change of facies eastward into the green clay. Transitionary stages 

may be seen at various places. At Asthall and at Bladon the characteristic 

gastropods (A. bladonensis) pass up into the Kemble Beds; and at Asthall 

they occupy nearly 5 ft. of hard sublithographic rock. 

In North Oxfordshire again, the beds containing the characteristic assemblage 

and immediately underlying the Kemble Beds are developed predominantly 

as limestones. At Sibford Mill, near Sibford Ferris, there are two 

beds crowded w 7 ith A. bladonensis and the lower can be seen to pass laterally 

into green clay; while in the eastern limekiln quarry at Rollright Railway 

Station there are three beds containing the characteristic gastropod, spread 

through a thickness of over 13 ft., with abundant Gervillia waltoni and Astarte 

fimbriata in some of the beds. 1 In the neighbouring Pest House railway-cutting 

east of Rollright Railway Station the main Fimbriata-waltoni Bed can still be 

seen, crammed with these two fossils, and also Aphanoptyxis bladonensis, 

Amberleya nodosa, Corbula hulliana and Protocardia subtrigona, though nearly 

everything else is now overgrown. 1 When the cutting was first made, Hudleston 

described this bed as 'a complete museum', but owing to a misidentification 

of the Astarte he called it the angulata bed. 2 

White Limestone, 20-30 ft. 

Still the most important and the most persistent of all the subdivisions of the 

Great Oolite Series, and from Gloucestershire northwards the Great Oolite par 

excellence, is the White Limestone. The upper beds are exposed in innumerable 

quarries all over the county, but the lower layers are rarely seen. 

As in Gloucestershire, the White Limestone often contains an abundance of 

corals, brachiopods, lamellibranchs, and gastropods. In Oxfordshire there is 

frequently near the top a band largely composed of Epithyris oxonica (the 

Lower Epithyris Bed), which at Kirtlington and about the Cherwell Valley 

fills the rock to a thickness of up to 8 ft. The brachiopods clearly had colonial 

habits, however, and the rock in which they lie is wedge-bedded (fig. 51, 

p. 290), so that in some exposures there may be no sign of a brachiopod, while 

in others specimens can be collected by the sackful. The gastropods occur 

more persistently, and three species have local epiboles always in constant 

sequence and of considerable help in making correlations. Below the Aphanoptyxis 

bladonensis epibole, which corresponds with the Fimbriata-waltoni beds, 

is nearly always a conspicuous band of a more slender and elongate gastropod, 

A. ardleyensis, the position of which is immediately below the Lower Epithyris 

Bed where that is present. Lower still is an equally conspicuous epibole of 

Nerinea eudesii, but this last has such a long local range (its teilzone is so large) 

that the species cannot be relied upon to have achieved its acme at the same 

time even in the confines of Oxfordshire. A short distance below this a fourth 

species, Ptygmatis bacillus d'Orb., abounds in certain places, recalling the Ptygmatis 

Bed of Stony Furlong and Aldgrove cuttings. Near Burford,over 5 ft. of 

1 Field-notes. 2 W. H. Hudleston, 1878, P.G.A., vol. v, p. 386.


rock are crowded with A. ardleyensis, and it seems highly probable that the bed 

is on the same horizon as that containing the species so abundantly at Condicote, 

in the Cotswolds, 10 miles to the north-west. Hence it has been traced 

in numerous quarries for 18 miles north-eastward to Ardley cutting, where it 

forms the so-called Nerinea Rock. 

The lower part of the White Limestone is exposed only in four places: the 

top of a quarry in the Taynton Stone at Milton under Wychwood, a quarry 

in the side of the Evenlode Valley at Whitehill Wood, a railway-cutting near 

Hook Norton, and the Ardley-Fritwell railway-cutting. The only complete 

exposure is the last, where the total thickness of the White Limestone is 32 ft. 

The lower half of the division is especially characterized by Clypeus 

mulleri, which rarely occurs at higher levels, and it has also yielded, very 

occasionally, ammonites identifiable as Tulites cf. subcontractus. Specimens 

have been found at Asthall, at a level of about 16-18 ft. from the top 1 (i.e. 

slightly below the middle) and in the Fritwell cutting, in the basal bed. 2 

The lower portion of the White Limestone may be very poorly fossiliferous, 

as at Whitehill Wood, where a total thickness of 25 ft. yields hardly any fossils 

of note (neither gastropods nor brachiopods) or it may contain extremely rich 

bands of brachiopods and echinoderms. At Ardley Railway Station Quarry 

there is near the base a thick marly bed crowded with Stiphrothyris sp. and 

some large Rhynchonellids, Clypeus mulleri, &c., but the bed dies out before 

reaching the Fritwell cutting. At Milton under Wychwood the lowest levels 

contain abundance of a small Epithyris. It is remarkable, however, that neither 

the Ornithella nor the particular Stiphrothyrid so abundant in the Ornithella 

Marls of Gloucestershire has been found in Oxfordshire. 

Hampen Marly Beds, 17-25 ft. 

The Hampen Marly Beds at Whitehill Wood railway-cutting, in the 

Evenlode Valley, attain a thickness of rather more than 20 ft., consisting, as 

in Gloucestershire, chiefly of grey and buff marls and marly clays, with some 

bands of marly or false-bedded limestone. There is a gradual passage downward 

into the Taynton Stone. No less than 6 ft. of the beds, both at the top 

and near the bottom, are crowded with large Rhynchonellids of the R. concinna 

group and large specimens of Ostrea sowerbyi, which thickly strew the 

slopes of the cutting. 3 

The whole of the Hampen Marly Beds, the thickness amounting to 

17-18 ft., is well exposed at Milton under Wychwood, beneath 22 ft. of White 

Limestone and above 10 ft. of Taynton Stone. This fine section was described 

in detail by Richardson. 4 As at Whitehill Wood cutting, there are two beds in 

the series crowded w 7 ith the large form of Ostrea sowerbyi, like those in the 

Kemble Beds, and Rhynchonella concinna. About 4 miles south of Milton the 

full thickness of the beds is again seen at Swinbrook, overlying the Taynton 

Stone, with a skimming of White Limestone in the soil above. The thickness 

is again about 17 ft., but R. concinna and oysters, though present, are rarer. 

1 W. J. Arkell, 1931, loc. cit., pp. 607-8. 

2 M. Odling, 1913, Q.J.G.S., vol. lxix, p. 490. See Madarites gldbretus S. Buck., T.A., 

vol. iii, p. 52. 


4 L. Richardson, 1910, Geol. Mag. [4], vol. vii, pp. 537-42. The Hampen Marly Beds 

are his Beds 13 to 17 inclusive.


The recognition of the Hampen Marly Beds, with all their characteristic 

features, as far east as the Evenlode Valley within two miles of Stonesfield, has 

thrown new light on the record of the section ascertained by the British 

Association at Stocky Bank, Stonesfield, in 1894-6, 1 to determine the stratigraphical 

position of the Stonesfield Slates. The scarped bank, part of which 

is still open to view, showed immediately below the White Limestone 17 ft. 

of 'marls and limestones with oysters and Rhynchonella concinna' (Walford's 

Beds 2-9) which now fall into line as the Hampen Marly Beds of the neighbouring 

Whitehill Wood cutting. 

There are no further exposures for 11 miles in the direction of strike until 

the Ardley-Fritwell railway-cuttings. Here the White Limestone is again 

underlain by a series of marls and predominantly argillaceous beds, with 

abundant Rhynchonella concinna and allied forms, and thousands of large 

Ostrea sowerbyi. Underneath are false-bedded oolites like the Taynton Stone. 

The marly series, which is here about 27 ft. thick, has been misidentified as 

'Neaeran Beds' by Odling 2 and by Thompson, 3 while the false-bedded limestones 

beneath have been mistaken by the same writers for Chipping Norton 

Limestone. By reason of both the fossils and the lithology, however, the marls 

are to be correlated with the Hampen Marly Beds and the limestone with the 

Taynton Stone. A conspicuous feature at the bottom of the Hampen Marly 

Beds, peculiar to these cuttings, is an argillaceous limestone full of black, 

shiny, pseudo-oolitic grains, called the Bird's Nest Rock. It yields abundant 

R. concinna and is the source of a specimen of Zigzagites imitator S. Buck. 4 

About 4 miles north-west of these cuttings the beds crowded with R. concinna 

and O. sowerbyi were formerly worked in the Allotments Quarry, Aynho, 

and this was the source of the type specimen of R. concinna (Sowerby). 5 

Taynton Stone, 10-25 ft- 

The great freestone quarries at Taynton, north-west of Burford, worked 

since at least the sixteenth century for the 'Burford Stone' mentioned by 

Robert Hooke and Plot, are now sadly overgrown, but fresh sections may still 

be seen at Milton under Wychwood and Swinbrook. The freestone at these 

places is the same as at Barrington, over the Gloucestershire border, and the 

Hampen Marly Beds are well exposed above. The downward sequence, 

however, is not visible until the Evenlode Valley near Stonesfield. 

In the Whitehill Wood railway-cutting and the adjoining Ashford Mill 

railway-cutting, the Taynton Stone is seen to have a thickness of about 20 ft. 6 

It consists as usual of white, false-bedded, more or less fissile, broken-shell 

oolite, with an impersistent marly zone near the top, by which it merges up 

into the Hampen Marly Beds. Ostrea sowerbyi is abundant, though usually 

broken, but other fossils are for the most part small, fragmentary and 

indeterminable. 

1 E. A. Walford, 1894-6, Repts. Brit. Assoc., Oxford, Ipswich and Liverpool; and 1917, 

Lower Oolite of North Oxford, p. 17. 

2 M. Odling, 1913, Q.J.G.Svol. lxix, pp. 484-511. 

3 B. Thompson, 1931, Q.J.G.S., vol. lxxxvi, pp. 436-8. 

4 S. S. Buckman, T.A., 1922, pi. ccci. 

5 E. A. Walford, 1917, Lower Oolite of North Oxford, p. 10. Specimens may still be collected 

in the soil of the allotments. Buckman wrongly assigned Sowerby's species to the Cornbrash,— 

see Douglas and Arkell, 1932, Q.J.G.S., vol. lxxxviii, p. 152. 


294 L O W E R OOLITES 

About 9 miles to the north-north-east there is another complete exposure 

of the Taynton Stone in the railway-cutting at Langton Bridge, north of 

Chipping Norton, with the Hampen Marly Beds above. Here the thickness 

is 17J ft., and the upper part (about 6 ft.) is very fissile and sandy. The 

topmost bed is a fissile calcareous and slightly micaceous sandstone, suggestive 

of the Stonesfield Slate: in fact H. B. Woodward grouped the Taynton Stone 

here as 'Stonesfield Slate Series'. But he remarked 'it is noteworthy that we 

have current-bedded shelly oolites below the slaty beds instead of above them 

as in other localities near Burford and Notgrove. It is not unlikely therefore, 

as suggested by Mr. Walford, that the slaty beds here are developed at a 

somewhat higher horizon in the series than elsewhere.' 1 A closer examination 

confirms the suggestion that this sandstone is not on the same horizon as the 

true Stonesfield Slate, for it is not only far too irregular to be used for roofing, 

but the most careful search fails to reveal any of the fossils so characteristic at 

Stonesfield and in the Cotswolds. By stratigraphical position as well as by the 

negative fossil-evidence, it is a sandy development of the upper part of the 

Taynton Stone. 

A similar sandy and fissile facies of the topmost beds is seen at Castle Barn 

Quarry, between Churchill and Chadlington, which otherwise shows a section 

closely comparable with that at Ashford Mill cutting. 2 

In the extreme north and north-east of the county the Taynton Stone is 

nowhere exposed, and it is possible that locally it is overlapped by the 

Hampen Marly Beds. On the east side of the Cherwell Valley, however, it is 

present again in the Fritwell cutting, where it is about 15 ft. thick and highly 

false-bedded and fissile. 

Stonesfield Slate Beds. 

We have seen that in the North Cotswolds the Stonesfield Slate Beds thin 

out eastward before reaching the Vale of Bourton and are entirely absent from 

the Roundhill railway-cutting and Stow on the Wold, where Taynton Stone 

overlaps them and rests on Fuller's Earth. 

East of the Vale of Moreton the Stonesfield Slate Beds continue to be absent 

all over North Oxfordshire and even down the Evenlode Valley to Charlbury 

and Ashford Mill cutting, within a mile of Stonesfield. The first good 

section, Castle Barn Quarry between Churchill and Chadlington, on the edge 

of the Vale of Moreton, shows almost the same conditions as Roundhill 

cutting, except that the Taynton Stone has overlapped not only the Stonesfield 

Slate Beds but also the Fuller's Earth. At one end of the quarry it rests 

on the Upper Estuarine Clay and at the other end upon the Chipping Norton 

Limestone. 3 An almost duplicate section is to be seen in the Ashford Mill 

cutting, about 6 miles to the south-east. Here, however, there is at the base of 

the Taynton Stone a bed crowded with large specimens of Ostrea sowerbyi, 

Rhynchonella deliciosa Buck., R. decora Buck., and corals. The Rhynchonellce 

and the stratigraphical position indicate that this is the Sevenhampton 

Rhynchonella Bed of the Cotswolds, and the top of the clays beneath contains 

the true Ostrea acuminata. It therefore appears that the topmost layers of the 

1 H.B. Woodward, 1894, p. 332. 

J More will be said of this section below (see fig. 52, p. 299). 

3 L. Richardson, 1911, Proc. Cots. N.F.C., vol. xvii, p. 223, and field-notes.

STONESFIELD SLATE: OXFORDSHIRE 295 

Stonesfield Slate Beds take part in the overlap, for they cut out the ragstone 

beds and the slate beds before being themselves overlapped by the Taynton 

Stone. 

In all the exposures in North Oxfordshire the Taynton Stone and Upper 

Estuarine Clay are separated by these thin and highly fossiliferous representatives 

of the topmost part of the Stonesfield Slate Beds. Both at Langton 

Bridge and at Sharp's Hill the Upper Estuarine Clay is immediately succeeded 

by a thin clay with Ostrea acuminata and O. sowerbyi (the Acuminata-sowerbyi 

Bed), overlain by the Sevenhampton Rhynchonella Bed, crowded with fossils. 

At Langton Bridge especially, the same small Stiphrothyris that occurs at 

Sevenhampton is abundant; and here a poorly-fossiliferous band of limestone 

intervenes between the two fossil-beds. Eastward this band thickens to 

i 2~ 2 2 ft- anc * overlaps the Acuminata-sowerbyi Bed, for at Tadmarton and 

near Deddington it rests directly upon the White Sands equivalent to the 

Chipping Norton Limestone. 1 

In the Fritwell cutting, also, there is no sign of the Acuminata-sowerbyi 

Bed or of any part of the Stonesfield Slate Beds. Gritty and marly limestones, 

containing only the large Ostrea sowerbyi of higher levels and fragmentary 

Rhynchonellids, intervene between the Taynton Stone and the representative 

of the Upper Estuarine Clay. 

Thus the development at Stonesfield of true sandy slate beds like those of 

the Cotswolds is a peculiar feature for Oxfordshire. They are absolutely 

restricted to a small area immediately under the village of Stonesfield and 

extending perhaps for 2 or 3 miles towards the north and north-east, where 

they seem to have been preserved in a shallow basin-shaped depression and to 

have been overlapped on all sides. This is less surprising when the extreme 

thinness of the actual slate bed is realized. The overwhelming palaeontological 

interest of the stratum sometimes gives rise to a false impression of its stratigraphical 

importance, but it is not more than ft. thick, as in the Cotswolds. 

Sometimes there may be two beds, but they are no thicker and only 

a few inches apart. The greatest thickness of slate and associated sandy beds is 

6 ft., recorded by Fitton, and in the shaft descended by Woodward there was 

only 4 ft. The slate is identical with that in the Cotswolds, consisting of dark 

grey, very fissile, micaceous, calcareous sandstone, occurring in concretionary 

masses known as 'pot-lids'. Ooliths are curiously distributed in streaks and 

patches, and there is a conspicuous band of well-rounded pebbles of hard 

oolite, as in the Cotswolds. According to Fitton the position of the pebble seam 

is in the best slate bed, the upper of two layers of pot-lids, lying in a sand. 2 

The use of the Stonesfield Slate dates back to an antiquity even more venerable 

than that of the Forest Marble. 

Plot tells us that already in the middle of the seventeenth century 'the 

Houses are covered, for the most part in Oxfordshire, not with Tiles but Flatstone, 

w T hereof the lightest, and that which imbibes the water least, is accounted 

the best. And such is that which they have at Stunsfield, where it is dug first in 

thick Cakes, about Michaelmas time, or before, to lie all the winter and receive 

the Frosts, which make it cleave in the Spring following into thinner Plates.' 3 

1 L. Richardson, 1922, ibid., vol. xxi, p. 130, and field notes. 

2 W. F. Fitton, 1828, Zool. Journ., vol. iii, p. 412; and transcribed 1894, J.R.B., p. 312. 

3 R. Plot, 1676, Nat. Hist. Oxfordshire, p. 78.


All the slate accessible at the surface was long ago worked out and for 

probably more than a century there has been no visible surface outcrop or 

exposure. Originally adit galleries 6 ft. high were driven into the hill-sides, 1 

but for many years latterly the material was reached only by vertical shafts, 

down which the slatters descended with ropes to depths of from 20 to 70 ft. 

below the surface. H. B. Woodward found that it was almost impossible for 

a geologist to study the succession as he descended these shafts, for with one 

hand he had to hold on to the rope and with the other he held a candle. Now 

the last mine has been abandoned and only the vast piles of debris remain to 

mark the old workings. 

The fauna is as peculiar as the lithic characters, the abundant little Trigonia 

impressa being found at no other horizon in the Jurassic System. Some of the 

surfaces of the slabs on the tip-heaps at Stonesfield show hundreds of specimens, 

the valves open but still united by the ligament. 

The fossils that have made the Stonesfield Slate famous the world over 

are the jaws and bones of small ancestral mammalia, occasionally found 

when the pits were in work. According to the latest reviser, Dr. G. G. Simpson, 

there are known altogether four species belonging to four genera, classed 

as follows: 2 

MULTITUBERCULATA Stereognathus ooliticus Charlesworth. 

TRICONODONTA Umphilestes broderipi Own. 

{ r fiasco lot her lum bucklandi (brodenp). 

PANTOTHERIA Amphitherium prevosti (V. Meyer). 

Dr. Simpson writes that 1 Stereognathus appears to be a last survivor of a 

group already found in the Rhaetic. The others as true mammals appear for 

the first time. Amphitherium is probably the most significant single genus of 

Mammalia known, for it represents a very early, very generalized stock, which 

. .. provides an ideal structural ancestor for all known post-Paleocene mammals 

except monotremes. , The known mammalian faunas of the Mesozoic, he 

remarks, 'stand out like lights in the vast darkness of the Age of Reptiles— 

and very dim lights most of them are. This mammalian prehistory is two to 

four times as long as the "historical period" which followed it, and yet the 

materials for the latter are literally many thousandfold those for the former. 

This . . . makes close scrutiny of the Mesozoic mammalia which are known the 

more necessary, and the results which are to be obtained from them the more 

precious.' 3 

The first discovery of these remarkable fossils was made by W. J. Broderip 

in 1812 or 1814, when he was a young man studying law at Oxford and at the 

same time attending Buckland's lectures on geology. One day two of the jaws 

were brought to his rooms in Oriel College by an old stonemason who collected 

for him, and both he and Buckland were convinced that they were jaws of 

mammals. But it was an established dictum that no mammals existed before 

the Tertiary, while these were embedded in unmistakable Stonesfield Slate; 

and even though in 1818 Cuvier visited Oxford and confirmed their opinion, 

it was not until 1824 that Buckland ventured on publication. He was followed 

1 W. D. Conybeare, 1822, in Conybeare and W. Phillips, Outlines of Geol. England and 

Wales, p. 204. 

2 G. G. Simpson, 1928, Cat. Mesozoic Mammalia Brit. Mus.t p. 198. 

3 Ibid., p. 199 and p. 7.

STONESFIELD SLATE MAMMALS 297 

in 1825 by Prevost, who had spent some time in Oxford. Both Prevost and 

Cuvier referred the bones to an unknown genus allied to the opossums. 

Critics immediately arose declaring that the jaws must be reptilian or even 

piscine, some of the fiercest opposition coming, in spite of Cuvier's verdict, 

from Paris. De Blainville, the loudest of the critics, mistook the internal 

groove shown on Buckland's figures for a suture. In 1838 Buckland made a 

pilgrimage to Paris with two specimens and converted all the French naturalists 

who saw them—Valenciennes, Dumeril, and Geoffrey St. Hilaire. On his 

return he handed over the jaw T s to Owen, who described, discussed and 

figured all the available material in 1838 and 1842. Owen finally settled the 

matter by showing the supposed suture to be a groove with an entire bottom, 

and pointing out numerous other mammalian features. 

The land fauna associated with the Stonesfield mammalia comprises two 

pterosaurs, Megalosaurus bucklandi (found also in the White Limestone and 

the Chipping Norton Limestone), and insects. The plants include ferns, 

cycads, conifers, and an undoubtedly dicotyledonous leaf, figured by Prof. 

Seward. 1 Before the Caytoniales were described by Dr. Hamshaw Thomas 

from the Yorkshire Inferior Oolite (see p. 219) this leaf was the earliest known 

specimen of an Angiosperm recovered from the stratified rocks. 

These remains were all drifted into a shallow sea from neighbouring land, 

for they are far outnumbered by the marine fauna, both vertebrate and 

invertebrate. There are remains of Teleosaurus, Steneosaurus, Plesiosaurus, 

a Chelonian, and about forty species of fish—including sharks, ganoids and 

a species of Ceratodus. 

Cephalopods are rare, but include Gracilisphinctes gracilis (J. Buck.), 

Micromphalites micromphalus (Phil.), 2 an unidentifiable species of Clydoniceras, 

and Nautilus baberi Mor. and Lyc. Long lists of lamellibranchs and gastropods 

have been published, 3 but the only really abundant and characteristic 

species are Trigonia impressa Sow., Gervillia ovata Sow\, Ostrea acuminata and 

O. sowerbyi, with crushed Rhynchonellids and numerous specimens of 

Chlamys and Camptonectes of the common Great Oolite species. 

Upper Estuarine Clay, 0-3 ft., and Sharp's Hill Beds, 0-10 ft.—'NEJERAN 

BEDS'. 

As already remarked, Richardson has traced the Upper Estuarine Clay 

from quarry to quarry through the North Cotswolds and North Oxfordshire 

into Northamptonshire, where it forms the base of the so-called 'Upper 

Estuarine Series'. Throughout this district, although it is unfossiliferous, it 

is unmistakable on account of its peculiar lithological appearance, its green 

and chocolate colours and heavy, greasy, quality. At the base there is frequently 

a black carbonaceous layer, and below that numerous pebbles and 

sometimes phosphatic nodules, which rest upon an uneven surface of the 

different beds below. 

Locally in North Oxfordshire the black carbonaceous layer that usually 

forms the base of the Upper Estuarine Clay is underlain by a pale seam of marl 

(usually 0-8 in.), mixed with pebbles but overlying the main pebble-bed. This 

1 A. C. Seward, 1904, Cat. Mes. Plants in Brit. Mus., pt. 2, p. 152 and pi. xi, figs. 5, 6 

2 S. S. Buckman, 1923, T.A., pi. CDLII. 

3 H.B.Woodward, 1894, J.R.B., pp. 314-17.


pale band is remarkable for containing in abundance the freshwater gastropod 

Viviparus langtonensis (Hudleston) 1 and more rarely Valvata comes Hudl., 1 

after which it is called the Viviparus Marl. The Viviparus superficially resembles 

the species in the Purbeck Marble, which, in fact, it approaches more 

nearly than that found in approximately contemporaneous beds in the Department 

of Indre, France, and in Scotland. 2 

This freshwater bed, with the pebble bed below, or where the freshwater 

fossils are absent, the Upper Estuarine Clay, is markedly discordant in its 

relations to the strata beneath. At Sharp's Hill, near Hook Norton, Richardson 

describes it as resting non-sequentially on an eroded surface of the lower beds. 

Tt indicates a change', he adds, 'and in places the non-sequence between it and 

the underlying deposits is far greater than at Sharp's Hill. At Castle Barn, for 

example, it rests directly upon the Chipping Norton Limestone.' 3 Subsequent 

extension of the quarry at Castle Barn has shown that the pebble bed there is 

very marked, comprising some 6 in. of rolled and bored lumps of hard 

Chipping Norton Limestone, intimately blended with the Viviparus Marl 

(fig. 5 2)- 

Before the widespread erosion which gave rise to the pebble bed and preceded 

the formation of these freshwater and estuarine deposits (and the extent 

of the erosion is denoted by the effects already referred to in the North Cotswolds) 

a series of highly fossiliferous marine deposits was accumulated over 

the central plateau of Oxfordshire, These were grouped by H. B. Woodward 

and other writers as Fuller's Earth and little attention was paid to them except 

by a local geologist, E. A. Walford of Banbury. Walford discovered the great 

palaeontological interest of the beds, and his valuable researches have been 

carried on and extended by Richardson. 

Walford grouped together all these beds, including the Upper Estuarine 

Clay and the Viviparus Marl, under the name Neaeran Beds, and Richardson 

at first followed this plan. Later, however, as the significance of the higher 

clays came to be realized, he restricted the name to the beds below the Upper 

Estuarine Clay, and if it is to be used at all there is no doubt that it should only 

apply to the strata below the plane of discordance. 4 

Apart from this the name Neaeran Beds is an unfortunate one for several 

reasons. In the first place specimens of Necera are only very occasionally to 

be found and are much more common in the Upper Estuarine Series of the 

Eastern Counties; the same species, N. ibbetsoni Mor. and Lyc., also occurs 

in the Hampen Marly Beds and I have even found it in the 'Forest Marble' 

of Kirtlington. 5 In the second place the correct name of the genus, by the 

rules of priority, should be Cuspidaria. For these reasons it is proposed to 

drop the name Neaeran Beds altogether, in favour of Upper Estuarine Clay and 

Sharp's Hill Beds. 

The succession is best illustrated by the type-section at Sharp's Hill, 

1 Figd. W. H. Hudleston, 'Alon. Inf. Oolite Gastropoda', Pal. Socpp. 488-9, pi. XLIV, 

figs, i a, b, 2 a, b; and pi. XLIII, fig. 27. 

2 See M. Cossmann, 1899, Bull. Soc. geol. France [3], vol. xxvii, pp. 136-43, 543-85, and 

pis. XIV-XVII. 


4 Richardson included in the Neaeran Beds the Viviparus Marl, but since it contains freshwater 

fossils while the Neaeran Beds are purely marine, and since it moreover succeeds the 

pebble bed, it is here grouped with the Upper Estuarine Clay. 

5 M. A. P. Dutertre informs me that it has an equally long range in the Boulonnais.

ROUNDHILL 

GLOS. 

CASTLE BARN 

NR. SARSDEN 

LANGTON 

BRIDGE 

SHARP'S HILL TADMARTON FRITWELL TOWCESTER 

HAMPEN tv;AR.|_y 

BEDS. WITH 

RH. CONCINNA 

& 0. SOWERBYI 

TAYNTON 

STONE 

OSTREA SOWER&vj 

Sevenhampron c 

rhynchcneua BED 

ACLK-'NAVvSOWEReyl 

t-DJ 

UPPCR E5T JARIN i 

CLAY 

^VVVyJ VIVI PAR US MARL 

1 D EB6LE BED 

CH;PP;NG NORTON 

LI\fE5T0NL : 

SEMES 

j|l| I I I ° «— 1— « : 

! : ; 

FIG. 52. Correlation of the lower part of the Great Oolite Series at some of the principal exposures in North Oxfordshire, at Roundhill, Glos., and at 

Towcaster, Northants. Vertical scale, 1 in. = 12 ft.


2 miles north-west of Hook Norton, minutely described by Walford and by 

Richardson. The sequence of fossil beds and grey and greenish clays is as 

follows (fig. 52): 

SECTION AT SHARP'S HILL, NEAR HOOK NORTON1 ft. in. 

SEVENHAMPTON RHYNCHONELLA BED: crowded with Rhynchonella communalis, 

R. decora, R. ? deliciosa and Ostrea sowerbyi . . . . 1 0 

Clay . . . . . . . . . . . . 1 0 

ACUMINATA-SOWERBYI BED: clay, full of whitened O. acuminata and some 

O. sowerbyi . . . . . . . . . . 6 

(non-sequence) 

UPPER ESTUARINE CLAY: tough, dark green, brown, and bluish clay, the 

basal 6 in. black and bituminous, almost resembling a coal seam 2 . . 3 o 

VIVIPARUS MARL AND PEBBLE BED: pale whitish marl with V. langtonensis, 

Ataphrus labadyei (d'Arch.) and Nerinea spp., and numerous pebbles 

and concretions, some phosphatic . . . . . . . 8 

(plane of erosion) 

SHARP'S HILL BEDS: total about 10 ft. 

Upper Nerinea Bed; limestone passing into marl; N. eudesii Mor. and 

Lyc., Aphanoptyxis tomesi Ark., &c. . . . . . . 1 9 

Coral Bed with Cyathophora bourgueti (ICryptoccenia delauneyi) . . 2 1 

Lower Nerinea Bed; limestone as above, 0-1 ft. . . . . 8 

Astarte oxoniensis Limestone, 0-8 in. . . . . . . . 5 

Marl parting . . . . . . . . . . . 3 

Exelissa Limestone; grey argillaceous limestone crowded with tiny black 

gastropods (Exelissa) and small lamellibranchs, 0-10 in. 6 

Limestone (impersistent) . . . . . . . . . 5 

Perna Bed: pale yellow and greenish marl and stone, full of Isognomon 

\Perna\ oxoniensis (Paris), &c., &c., 1 ft. to . . . . . 1 6 

Reddish-brown sandy layer with nodules of shaly limestone . . . 8 

Black clay . . . . . . . . . . . 2 0 

[Chipping Norton Limestone below, 19 ft.] 

It is exceptional for the Sharp's Hill Beds to be so fully represented. Usually 

the thickness is not more than 5-8 ft., owing to overstep by the Viviparus 

Marl and Upper Estuarine Clay, as well as to minor non-sequences within the 

series. Nevertheless the beds have been traced over nearly all the central 

plateau of Oxfordshire, between the valleys of the Evenlode and the Cherwell, 

from Sharp's Hill and Temple Mill north of HookNorton,by Chipping Norton, 

Chastleton, Enstone and Chadlington, to Charlbury and the Ashford Mill 

railway-cutting near Stonesfield. Only towards the east are they absent, 

where at Tadmarton, Duns Tew and Fritwell, as already mentioned, either 

the Sevenhampton Rhynchonella Bed or a band of limestone immediately 

below it rests directly upon White Sands equivalent to the Chipping Norton 

Limestone. At Fritwell the Upper Estuarine Clay may be represented by a 

thin black peaty seam, only a few inches thick. 

Where the Sharp's Hill Beds are well developed the fauna is extremely 

interesting. The pale argillaceous limestone crowded with tiny black gastro- 

1 Condensed from L. Richardson, 1911, loc. cit., pp. 206-9. 

2 Below this in Walford's record come 3 ft. of limestones and marls, but Richardson and 

Paris were unable to find them in 1911 and they have not appeared since, although the quarry 

is still in work.

CHIPPING NORTON LIMESTONE: OXFORDSHIRE 301 

pods of the genus Exelissa is unique in the British Jurassic. At Enstone, 

Sharp's Hill and a few other places, thePerna Bed has also yielded a unique 

assemblage of Isognomon and Gervillia, collected by Richardson and described 

by Paris—I. oxoniensis (Paris), G. enstonensis Paris, G. richardsoni Paris. 1 The 

Nerinea Beds contain also a unique gastropod, Aphanoptyxis tomesi Ark., 

found at Sharp's Hill, near Chipping Norton, and in Ashford Mill cutting, 

associated with the common Nerinea eudesii Mor. and Lyc., all superbly 

preserved. 2 Most of the sections also show clays crowded with Placunopsis 

socialis. 

To any one familiar with these beds in their type-localities, it is difficult to 

see how they can have been confused with the Hampen Marly Beds at Fritwell, 

and so with the Upper Estuarine Series of Northamptonshire. The whole 

fauna presents a marked contrast with those beds, with their characteristic 

masses of Ostrea sowerbyi and Rhynchonella concinna. 

Chipping Norton Limestone, 10-25 ft- 

The Chipping Norton Limestone continues into Oxfordshire from the 

North Cotswolds by w r ay of Oddington, near Stow on the Wold, and its distribution 

and stratigraphy have been carefully worked out by Richardson. 

About the type-locality it forms the chief surface-feature. It is quarried 

extensively at numerous places on the plateau to the south and west of the 

town of Chipping Norton about Chastleton, Sarsden, Chadlington, Enstone 

and Charlbury. It can also be well seen in Langton Bridge railway-cutting, 

west of Rollright Railway Station, while southward it is co-extensive with the 

Sharp's Hill Beds, down the Evenlode Valley to Cornbury Park, Fawler 

and Stonesfield. 

Over all this area it consists of a fine-grained, cream-coloured or white, 

oolitic limestone, some 15-20 ft. thick, often with black carbonaceous specks 

or flecks of pulverized lignite, and very poorly fossiliferous. Only occasionally 

a band of Pseudomelanice occurs near the top. From time to time, however, 

collectors watching the extensive quarries have made important finds. Bones 

of Cetiosaurus oxoniensis were long ago found at Sarsden and Padbury's Quarry, 

Chipping Norton. 3 Of ammonites, a single specimen of Oppelia cf. fusca was 

found by Richardson at Oakham Quarry, between Little Rollright and Little 

Compton, in the upper part of the series. 4 This guiding ammonite is of the 

highest value in correlation and enables it to be said that the Chipping Norton 

Limestone of the type-locality is contemporaneous with the lower part of the 

Low r er Fuller's Earth Clay farther south—as might be expected on stratigraphical 

grounds, from its occurrence above the Clypeus Grit. Since the 

upper part of the Chipping Norton Limestone can be dated to the fusca 

hemera, or equivalent to the Scroff and some of the superincumbent clay, the 

lower part may be inferred to be of zigzag date, or equivalent to the Zigzag Bed 

and the Crackment Limestone of Dorset and Somerset. An instructive parallel 

may therefore be drawn between the Chipping Norton Limestone and the 

Calcaire de Caen. 

1 E. T. Paris, 1911. Proc. Cots. N.F.C., vol. xvii, pp. 233-5 and pi. XXVII. 

2 W. J. Arkell, 1931, loc. cit., p. 619, and pi. L, figs. 15-17. 

3 J. Phillips, 1871, Geol. Oxford, pp. 164, 245. 

4 L. Richardson, 1911, Proc. Cots. N.F.C., vol. xvii, p. 228, and 1922, ibid., vol.xxi, p. 116.

HAMPEN 

MARLY BEDS 

TAYNTON 

STONE 

STONESFI ELD 

SLATE BEDS 

FULLER'S EARTH 

UP. ESTUARIN" " 

CLAy 

NORTH 

COTSWOLDS 

GREAT 

OOLITE 

luPPER 

/ESTUARINE 

JSERlES 

WHITE 5ANW 

FIG. 53. Horizontal section through the Great Oolite Series from the North Cotswolds across North Oxfordshire to the southern boundary of 

Northamptonshire, to show the relations of the beds and the passage to the Upper Estuarine Series. The top of the White Limestone is adjusted 

to the horizontal. C.N.L. = Chipping Norton Limestone; S.H.B. = Sharp's Hill Beds; U.T.G. = Upper Trigonia Grit; the thick black line = the 

Upper Estuarine Clay, with basal pebble bed and locally the Viviparus Marl.

CHIPPING NORTON LIMESTONE: OXFORDSHIRE 303 

About Chipping Norton and over the plateau to the south and west the 

Limestone is divided into two roughly equal parts by a very hard band 

graphically named the Knotty Bed, but little difference is to be detected in 

the nature of the stone above and below it. To the north and east of Chipping 

Norton, however, the Knotty Bed begins to separate two very distinct series 

of strata. At the same time it becomes itself highly fossiliferous and was named 

by Walford after its principal fossil, the Trigonia signata Bed. 

The upper portion of the Limestone is the first to change, passing towards 

the Cherwell Valley into sands, sandstones and sandy limestones, which 

alternate about Hook Norton, Swerford, Sharp's Hill and Tew, in a manner 

reminiscent of the same beds in the North Cotswolds. This arenaceous facies 

has been named by Richardson the Swerford Beds. They are 10-15 ft- thick 

and are especially well seen at Swerford, at Langton Bridge road-cutting near 

Rollright, and at Great Tew, where perfect gradations from siliceous limestone 

to white sand may be studied. 

The lower portion, below the Knotty Bed or T. signata Bed, likewise takes 

on a more arenaceous facies east and north of Chipping Norton, but it is more 

massive than the upper. Instead of passing into white sands like the Swerford 

Beds, it develops into massive brown sandstones and flaggy, sandy limestones 

('planking') with brown sand and occasionally marly bands. Often the lowest 

layers are highly fossiliferous, yielding in particular multitudes of Pseudomonotis 

lycetti Rollier and plant-remains and lignite. To this series, including 

the Trigonia signata Bed above, the name Hook Norton Beds has been applied 

by Walford and subsequent writers. The average thickness is 10-15 ft. 

Just as the Clypeus Grit overlaps the Upper Trigonia Grit at the Vale of 

Moreton, so it is itself overlapped between the Valleys of the Evenlode and 

Cherwell by the Hook Norton Beds, and they in turn are overlapped by the 

Swerford Beds east of the Cherwell. At the same time both the Hook Norton 

and the Swerford Beds become progressively more sandy. The stages of this 

process have been elucidated by Richardson by means of prolonged and careful 

field-work, and the subject here merits attention in a little more detail than this 

passing statement (fig. 53). 

At Sharp's Hill and in the Hook Norton railway-cutting the Hook Norton 

Beds consist of hard, blue-hearted, brown sandstone and siliceous limestones, 

which overlie the attenuated representative of the Clypeus Grit. On the east 

side of the Cherwell Valley, however, they have become more sandy and rest 

directly upon Upper Lias clay. This is well seen in the Fritwell railwaycutting, 

near the tunnel mouth, and at Newbottle Spinney, near Aynho. 1 At 

these places the lowest beds are highly ferruginous and marly and contain, 

besides abundant fossils, numerous small pebbles of dark Upper Lias claystone. 

Still farther north and east the Hook Norton Beds attenuate rapidly, being 

last seen at Turweston, near Brackley, as a 4-in. conglomeratic band with 

pebbles of Upper Lias claystone. A few miles to the north again, in the railwaycutting 

between Greatworth and Helmdon, they have disappeared entirely. 2 

The beginning of the overlap of the Hook Norton Beds by the Swerford 

Beds is seen at Swerford and Great Tew, where the two series are divided by 

1,2 L. Richardson, 1923, 'Certain Jurassic Strata of Southern Northamptonshire', P.G.A., 

vol.xxxiv, pp. 99, 103.


a conglomeratic band, containing rolled and waterworn shells and pebbles of 

Hook Norton Beds, bored and encrusted with oysters and Serpulce. 1 Towards 

the Cherwell Valley the slight discordance between the two series becomes 

accentuated. The Swerford Beds at the same time pass entirely into sands, 

which weather white, but may be bluish or black when freshly exposed and 

often contain much carbonaceous matter towards the top. Such sands are 

seen at Tadmarton and Banbury on the west side of the Cherwell Valley, and 

on the east side they reappear in the Fritwell railway-cutting, at Charlton near 

Aynho, about Brackley, and at numerous other places. 

The most instructive section of all is that in the Fritwell cutting, where the 

black and white sands of the Swerford Beds fill deep channels hollowed out 

in the underlying Hook Norton Beds (see Plate XIII), sometimes to a depth 

of at least 10 ft. This prepares us for the section at Turweston near Brackley, 

7 miles to the north-east, w r here only a thin conglomeratic band separates the 

white sands of the Swerford Beds from the Upper Lias. Beyond this, as just 

stated, the Hook Norton Beds are nowhere seen (see map, fig. 38, p. 207). 

The further continuation of the Swerford Beds, although they encroach into 

Northamptonshire, is more appropriately dealt with here, since they do not 

come into any more than the southern fringe of the Northants.-Lincs. area. 

Richardson has traced them from across the Cherwell Valley into the 

Brackley and Towcester districts, at Turweston, Helmdon, Easton Neston, 

Blisworth and Gayton, and so into the country immediately surrounding 

Northampton, where they are the well-known White Sands, long known at 

New Duston and many other places. 2 Here, in the north, they rest upon the 

Variable Beds of the Lower Inferior Oolite, but, as explained in Chapter VIII, 

in the south, about Brackley, they repose directly upon Upper Lias (fig. 38, 

p. 207, and fig. 47, p. 245; and fig. 53, p. 302). _ 

The White Sand of Southern Northamptonshire was formerly regarded as 

part of the Lower Inferior Oolite and was grouped with the 'Lower Estuarine 

Series'; in fact similar white sand undoubtedly passes under the Lincolnshire 

Limestone farther north. On this account Thompson 3 did not accept Richardson's 

correlation of any of the White Sand of S. Northamptonshire with the 

fusca zone. But that all the white sand formerly called 'Lower Estuarine' or 

4 Northampton Sand' could not be synchronous was realized by Hudleston so 

long ago as 1878, when he pointed out that in the Hook Norton and Banbury 

district similar sand overlies the Clypeus Grit. 4 Richardson has now carried 

the matter farther by showing that on the east side of the Cherwell Valley, on 

the borders of Oxon. and Northants., White Sand overlies the Hook Norton 

Beds (as may be verified in the Fritwell cutting, where the Hook Norton Beds 

are highly fossiliferous, as at Newbottle Spinney). Since he has also traced it 

laterally into the upper part of the Chipping Norton Limestone via the Swerford 

Beds, the case seems to be conclusively proved. 

In the district around Northampton, however, the two white sands of 

different ages come into juxtaposition (see fig. 47, p. 245), and much detailed 

1 L. Richardson, 1922, 'Certain Jurassic Strata of the Banbury District', Proc. Cots. N.F.C., 

vol. xxi, p. 125 ; and 1911, ibid., vol. xvii, p. 218. 

2 L. Richardson, 1923, loc. cit.; and 1921, 'Excursion to the Banbury and Towcester 

Districts', P.O.A., vol. xxxii, pp. 109-22. 

3 B. Thompson, 1924, P.G.A., vol. xxxv, pp. 67-76. 

4 W. H. Hudleston, 1878, P.G.A., vol. v, p. 382.

GREAT OOLITE SERIES: NORTHANTS—LINCOLN 305 

work will be required to separate them in every exposure. At New Duston 

and elsewhere a well-defined, even surface marks off the softer fusca White 

Sand from the harder brown Variable Beds or 'Planking' of the Lower Inferior 

Oolite, but the actual passage of brown sandstones of the Variable Beds 

laterally into white sand was described and figured by Woodward at Spratton 

Ironstone workings near Brixworth. 1 

V. NORTHANTS—LINCOLNSHIRE 

Compared with the complex development in Oxfordshire, the Great Oolite 

Series of the long outcrop from Northants and Bucks, through Rutland and 

Lincolnshire is a simple formation. It consists of the following three divisions: 

ft. 

Blisworth Clay . . . . . . . . . . 5-30 

Great Oolite [White] Limestone . . . . . . . 15-30 

Upper Estuarine Series [— mainly Hampen Marly Beds] . . . 10-35 

Some of this apparent simplicity may be due only to the insufficiency of our 

knowledge of the detailed succession of the faunas. But although modern 

refinements of stratigraphy might lead to the detection of further possibilities 

of subdivision, we already have thorough and accurate descriptions of exposures 

all along the outcrop, from the pens of Judd, Samuel Sharp, and others. 

Blisworth Clay, usually 10-30 fc. 

The Blisworth Clay, so named by Samuel Sharp in 1870, has been called 

the Great Oolite Clay; but that name was first applied by Sharp to the Upper 

Estuarine Series, and since it is also less explicit, it should be dropped. 

The clays are variegated bluish, greenish or purplish grey, black or yellow, 

with impersistent sandy bands, ironstone nodules, or thin oyster-beds composed 

of Ostrea sowerbyi, O. subrugulosa Mor. and Lyc. or Placunopsis socialis 

Mor. and Lyc. Other fossils are rarely to be obtained. In their general 

appearance the strata much resemble the Upper Estuarine Series below, and 

like them are suggestive of fluvio-marine deposits. 

In the south of Northamptonshire the Blisworth Clay was found by the 

Survey to be too thin to be shown on a map. It thickens in the north of the 

county and in Lincolnshire, being 12 ft. thick at Thrapston, about 14 ft. at 

Peterborough and 20- 30 ft. about Lincoln. North of Lincoln, at Brigg, it is 

still 24^ ft. thick, beyond which the whole Great Oolite Series undergoes 

great changes towards the Market Weighton Axis. 

The explanation of the thickening is to be found in the quarries about the 

borders of Oxfordshire, Buckinghamshire, and Northamptonshire. Here it 

can be seen that the Blisworth Clay is a lateral development of the 'Forest 

Marble', and many degrees of transition occur from one facies to the other. 

The change does not take place once and for all, but there are alternations of 

limestone and clay. For instance, at Bradwell, 2 miles east of Stony Stratford, 

a section described by Woodward 2 showed between the Cornbrash and the 

Great Oolite Limestone ft. of Blisworth Clay with an oyster-bed at the 

top, while about 10 miles to the north-east, at Newton Blossomville east of 

Olney, a large modern quarry shows a like thickness of massive Forest Marble. 

The two facies are interchangeable, just as in the Kemble Beds of Long Hand- 


2 Ibid., p. 392. 

h."»4:i71 Y


borough and other places in Oxfordshire. Where the clay is thin it is in part 

represented by Forest Marble, which has been grouped with the Great Oolite 

Limestone. The marble facies recurs at intervals for many miles northward, 

being seen, with some Blisworth Clay above it, about Oundle and Peterborough. 

In the Peterborough district it was formerly worked for the same 

purposes as in Oxfordshire, under the name of Alwalton Marble, and was 

used for the slender shafts on the front of Peterborough Cathedral (erected in 

the thirteenth century). 1 The workings lay along the steep escarpment of 

Alwalton Lynch, but Judd records that they were all closed before the time of 

his visit in the 1870's. The 'marble' appears to have taken a good polish but 

not to have been very durable. 2 

There can be no doubt that the bulk of the Blisworth Clay in most places 

represents the Kemble Beds. The sections at Long Handborough and at 

Islip show that towards the north-east the Wychwood Beds and Bradford 

Beds either thin out and are overlapped by, or are overstepped by, the Cornbrash, 

and it follows from this, as well as from the lithology of the beds, that the 

Forest Marble to the north and east is most likely to be Kemble Beds. Indeed, 

the massive limestone of Newton Blossomville and the Alwalton Marble are 

indistinguishable from the Kemble Beds of parts of Oxfordshire and 

Gloucestershire, while the clays with abundant Placunopsis socialis and Ostrea 

sowerbyi agree well with those into which the Kemble Beds pass at Handborough, 

Kirtlington and Blackthorn Hill, near Oxford. The only difference 

is that the clays become more fluvio-marine, with their intercalations of sand 

and their variegated colours, while the ribbed form of Ostrea sowerbyi, named 

O. subrugulosa Mor. and Lyc., not met with south of Oxfordshire, becomes 

predominant. This shell seems to be a local race of O« sowerbyi, in which 

radial ribs, such as are seen in incipient stages on certain specimens of var. 

elongata in Dorset, have become fixed. 

The possibility of Bradford Beds and even Wychwood Beds recurring north 

of Oxfordshire, at least locally in pre-Cornbrash synclines, cannot be excluded, 

for old records of fossils said to have been collected by the Rev. Griesbach in 

the Cornbrash of Rushden, and certain brachiopods preserved in the Davidson 

collection, ex Griesbach collection, if they really came from Rushden, indicate 

the presence of the Bradford Fossil Bed. They include Kutchirhynchia 

morieri, identical with Bradfordian specimens. 3 

Another subdivision of the Great Oolite Series which probably contributes 

to form the basal portion of the Blisworth Clay is the Fimbriata-waltoni Beds. 

They remain in the form of marly limestones, full of the typical fossils, alternating 

with greenish clays, at least as far as the Ouse Valley between Buckingham 

and Stony Stratford, where they are exposed near Thornton. 4 At Oundle, 

in a large quarry near the George Inn, there is some indication that they have 

almost completely passed into the base of the Blisworth Clay, for the only 

sign of the fossiliferous limestone facies left is a 4-in. band of soft argillaceous 

marlstone, full of small specimens of Corbula hulliana and Gervillia waltoni. 

This lies 8 in. above the local bottom of the Blisworth Clay. 4 Above it is a 

1 S. Sharp, 1873, Q.J.G.S., vol. xxix, p. 278. 

2 J - W. Judd, 1875, 'Geol. Rutland', Mem. Geol. Surv., p. 209. 

3 See J. A. Douglas and W. J. Arkell, 1932, Q.J.G.S., vol. lxxxviii, p. 154. 

4 Field-notes.

GREAT OOLITE SERIES: NORTHANTS—LINCOLN 307 

widespread feature of the clay in this district, a band of ironstone nodules. 

They are so abundant in some places that they have been dug for iron, between 

100 and 200 tons having once been raised at Bottlebridge, near Overton 

Longville, and sent to Wellingborough to be smelted. 1 

White Limestone, 15-30 ft. 

If the Forest Marble, which we have seen to belong more rightly with the 

Blisworth Clay, be excluded, the Great Oolite Limestone of this area corresponds 

with the White Limestone. Both lithologically and palaeontologically 

there is close agreement. The rock is very rarely oolitic and generally of the 

creamy or pinkish-grey marly type, which already predominates in Oxfordshire. 

It is incomprehensible how Lycett, after visiting the Great Oolite 

quarries at Kingsthorpe, Duston and Blisworth under the guidance of Samuel 

Sharp, could have said that it seemed to him to correspond with the Forest 

Marble of East Gloucestershire and North Wiltshire. He supported this 

statement by quoting a number of fossils all characteristic of the White 

Limestone and (in part) Kemble Beds. 2 

From the Ardley-Fritwell cuttings the White Limestone may be traced in 

numerous minor exposures along the sides of the Ouse Valley and through 

the Towcester and Northampton country so well described by Sharp. The 

thickness is about 30 ft. in the south and is gradually reduced to about 20 ft. 

at Peterborough and northwards to Lincoln. There are good sections showing 

the greater part of the series at Kingsthorpe, Blisworth and in the Thrapston 

district. The detailed palaeontological succession has still to be worked out, 

but it is clear that in general it is the same as in Oxfordshire. Towards the 

top are beds of Ostrea sowerbyi and O. subrugulosa and in the middle portions 

fossil-beds full of corals, Epithyrids, lamellibranchs and gastropods. E. 

oxonica is met with intermittently in typical colonies over all this area, at least 

as far north as Thrapston, while corals occur in abundance as far as Belmesthorpe. 

3 At many places in the Peterborough and Stamford districts (e.g. 

Helpston) typical White Limestone is quarried, full of Isastrcea or Epithyris 

oxonica or such characteristic mollusca as Parallelodon rugosum (Buck.), 

Barbatia pratti (Mor. and Lyc.), Modiola imbricata Sow. and the Nerineidae. 

At the base of the White Limestone at Kingsthorpe and at Blisworth three 

'large smooth Ammonites, some 15 inches in diameter' and identified by 

Etheridge as 'old and smooth individuals of A. gracilis Buck.', were obtained. 4 

It is interesting to notice the reappearance of the Ornithella digonoides of 

Gloucestershire at Wootton Hall south of Northampton, and at Wollaston, 

where it was recorded by the earlier geologists as O. digojia and taken for 

'occasional evidence of beds that represent the Bradford Clay'. 5 But, as we 

now know, it is somewhat different from O. digona and occurs near Cirencester 

and Fairford below the Kemble Beds, in the White Limestone. 

1 J. W. Judd, 1875, loc. cit., p. 217. 

2 J. Lycett, in Sharp, 1870, Q.J.G.S., vol. xxvi, p. 379. 

3 J- W. Judd, 1875, loc. cit., p. 209. Corals still occur sporadically as far north as Lincoln; 

seeJ.R.B., p. 427. 

4 S. Sharp, 1870, loc. cit., p. 361. 

5 H. B. Woodward, 1894,J.R.B., pp. 396 and 402-3. Note that Woodward was led to group 

the bed in which it occurs as 'base of the Great Oolite Clay* and this misled Buckman into 

considering the Great Oolite Clay as * digonoides hemera'. But it occurs in a bed with Lima 

•cardiiformis and *T. maxillata\ lithologically and palaeontologically White Limestone.


In places the rock, by reason of the total absence of ooliths and a rubbly 

quality acquired on weathering, becomes very difficult to distinguish from 

shelly Lower Cornbrash. This has been emphasized by Judd and other 

Surveyors, 1 and it led to a number of typical White Limestone fossils, which 

never occur in the Cornbrash, having been figured as Cornbrash species by 

Sowerby in the Mineral Conchology over a century ago. About Oundle there 

is a rock crowded with Astarte and other shells, which bears an unmistakable 

resemblance to Lower Cornbrash; but the Astarte is A. rotunda of the Bath 

Great Oolite, not A. hilpertonensis of the Cornbrash. 

Upper Estuarine Series, 10-35 ft- 

From the Oxfordshire border all along the outcrop to North Lincolnshire 

'the lowest division of the Great Oolite consists of clays, occasionally very 

sandy, of various colours, light blue being the predominant one, but bright 

tints of green, purple, &c. being not uncommon'. 

'Interstratified with the clays', wrote Judd, in his famous Rutland Memoir, 2 'are 

bands of sandy stone, with vertical plant-markings and layers of shells, sometimes 

marine, as Pholadomya, Modiola, Ostrea, Necera, &c., at other times fresh-water, as 

*'Cyrena'\ Unio, &c. Beds full of small calcareous concretions and bands of 4 'beef'' 

or fibrous carbonate of lime also frequently occur, and the sections sometimes 

closely resemble those of the Purbeck beds. In its lower part this series consists 

usually, but not always, of white clays passing into sands. At the base of these clays 

there is always found a thin band of nodular ironstone, seldom much more than 

one foot in thickness (fig. 54); this "ironstone junction-band" is everywhere conspicuous 

and marks the limit between the Great and Inferior Oolite Series... . There 

is very decided evidence of a break, accompanied by slight unconformity, between 

these two series in the Midland area. All the characters presented by the beds of 

the Upper Estuarine Series point to the conclusion that they were accumulated 

under an alternation of marine and fresh-water conditions. . . 

'The fresh-water fossils are for the most part too badly preserved for specific 

determination/ adds H. B. Woodward; 'the only fresh-water species identified is 

"Cyrena" cunninghami. 3 None of the plant-remains, so far as I am aware, have been 

determined. The "rootlets" occur at different horizons, and do not in themselves 

mark any important break.' 4 

The thickness is usually between 20 and 30 ft., but in the area south of 

Lincoln, at the Essendine railway-cuttings and towards Peterborough, it is 

slightly more (up to 35 and possibly in at least one place 40 ft.). 

Since the work of Sharp and Judd our knowledge of the Upper Estuarine 

Series in Northamptonshire has been greatly increased by the publications of 

Mr. B. Thompson, and the details he has supplied of this most southerly 

part of the outcrop have rendered correlation with the subdivisions of the 

Great Oolite Series in Oxfordshire more feasible. 

Judd stated simply 'The Upper Estuarine Series is on the same geological 

horizon as the Stonesfield Slate', and this view was tacitly accepted for half 

a century. 5 But there is no foundation for the correlation except a certain 

1 J. W. Judd, 1875, 'Geol. Rutland', p. 202, &c. 

2 Ibid., pp. 188-9. 

3 He also records Paludina \Viviparus\. Thompson recorded V.langtonensis (Hudl.), but as 

he believed it to be a Natica the identification is open to doubt (Q.J.G.S., vol. lxxxvi, p. 439). 


5 J. W. Judd, 1875, loc. cit., pp. 186 and 90.

UPPER ESTUARINE SERIES: NORTHANTS—LINCOLN 309 

lithological resemblance in some of the bands, and since the Stonesfield Slate 

bed (the only part of the series yielding the plants and land vertebrates which 

qualify it to be considered of 'estuarine' facies) is only ft. thick, it would 

require strong palaeontological evidence to maintain such a correlation. In 

reality none of the characteristic fauna of the Stonesfield Slate (as enumerated 

above) occurs in the Upper Estuarine Series. On the other hand, there are 

undeniable palaeontological and lithological reasons for correlating the greater 

part of the series with the Hampen Marly Beds. 

FIG. 54. 'Section at Northampton race-course', showing the Upper Estuarine Series, with 

the Ironstone Junction Band at the base, resting unconformably upon the White Sands 

(fusca zone?). (From J. W. Judd, 1875, 'Geol. Rutland*, Mem. Geol. Survp. 34.) 

As the result of a comparative study of a very large number of exposures all 

over Northamptonshire, Beeby Thompson has ascertained that the Upper 

Estuarine Series comprises three main stratigraphical divisions: a central block 

of sandy and shelly limestones, generally crowded with large Rhynchonellids 

and Ostrea sowerbyi—the Upper Estuarine Limestones—2^-15 ft. thick, 

sandwiched between two clay divisions. The details according to him are as 

follows : l 

IDEAL SECTION OF THE UPPER ESTUARINE SERIES 

IN NORTHAMPTONSHIRE 

(Condensed from Beeby Thompson.) 

BEDS ABOVE THE ESTUARINE LIMESTONES: 5—16J ft. 

Upper Freshwater Beds: variegated clays, blue, green and red, with abundant 

vegetable matter and vertical (Pplant) markings. Fossils rare, generally absent. 

3 ft. at Finedon to ft. at Moulton Park Farm. 

Corbula and Astarte Beds: pale green or grey clays with many fossils as casts; 

Corbula attenuata, C. hulliana, and Astarte angulata predominant, with 

Cuspidaria ibbetsoni, Placunopsis socialis, &c. Vertical markings. 2£ ft. at Brigstock 

to 7 ft. at Roade. 

Placunopsis, Nucula, and 'Cyprina' Beds: clays, 0-2J ft. thick, detected at a few 

places only (Hopping Hill, Moulton Park Farm). 

1 B.Thompson, 1930, Q.J.G.S., vol. lxxxvi, pp. 43i~4-


UPPER ESTUARINE LIMESTONES or RHYNCHONELLA BEDS: 2^—15 ft. 

There are two bands of limestone, each containing large Rhynchonella concinna 

and oysters, with an oyster bed, largely composed of Ostrea sowerbyi, above the 

upper course and below the lower. In the middle and west of Northamptonshire 

the two courses are divided by a soft parting only a few inches in thickness, 

but in the east of the county, as at Brigstock, the parting grows into 6 ft. of beds 

—unfossiliferous ferruginous sandstone and dark pyritous clay, with vertical 

markings. 

BEDS BELOW THE ESTUARINE LIMESTONES: 3-18 ft. [UPPER ESTUARINE CLAY of 

Richardson.] 

Lower Freshwater (or Brackish-water) Beds: variegated clays, usually containing 

abundant vegetable matter and vertical markings. Fossils rare. Thompson 

believed this division to be the home of the supposed 'CyrencC often mentioned 

farther north by Judd, because nowhere in Northamptonshire did he find any 

fossil that he could so identify. 

Ironstone Junction-bed: J-i ft. 

Mr. Thompson's work has confirmed the view that the series becomes 

attenuated down the dip-slope in SE. Northamptonshire, in the exposures at 

Rushden, Higham Ferrers, Raunds, Denford, &c., east of the Nene Valley. 

As Judd perceived, this is doubtless due to increasing proximity to the London 

landmass, and Thompson has shown that it is brought about by overlap of the 

Upper Freshwater Beds across all the subjacent portions of the series on to 

Upper Lias. Thompson believed that the overlap was due to a local anticline 

with a Caledonian strike, parallel to the Nene Valley, but he based this view 

upon two doubtful borings farther east, one of which he himself queried, and 

both of which are capable of other explanations. 1 To say the least, it is extremely 

doubtful whether the Upper Estuarine Series ever thickens again 

south-east of the outcrop. 

Thompson's views on the probable correlation of the Upper Estuarine 

Series with the strata to westward, over the Oxfordshire border, may be 

summed up in his statement that 'The Upper Estuarine Beds above the 

[Estuarine] Limestones in Northamptonshire correspond to the Neaeran Beds 

of Northern Oxfordshire, as defined by Odling in his description of the Ardley 

section (1913, p. 491) but not as defined by Walford in his detailed description of 

Sharp's Hill. yz He supports this statement by means of comparative columns, 

which show a very fair degree of correspondence between Ardley and 

Northants, and by a note from Buckman to the effect that 'the similarity 

(rather identity) of Rhynchonellas in the Estuarine Limestone of Northamptonshire 

and the Bird's Nest Rock of Ardley and top of Bed (2) shows that they 

can be correlated as contemporaneous'. 

As we have seen, the strata in the Ardley cuttings with the Bird's Nest Rock 

at the base, misidentified as 'Neaeran Beds' and Chipping Norton Limestone 

by Odling, correspond in reality with the Hampen Marly Beds, and have 

nothing whatever to do with Walford's Neaeran Beds in North Oxfordshire. 

The abundant large Rhynchonella of the Bird's Nest Rock is identical with 

that so common in the Hampen Marly Beds in the Evenlode Valley, at Milton 

1 B. Thompson, 1930, loc. cit., p. 452. 

2 B. Thompson, 1930, loc. cit., p. 436. The italics are mine.

UPPER ESTUARINE SERIES: NORTHANTS—LINCOLN 311 

under Wychwood and Swinbrook, and it is the same as the typical R. concinna 

of Aynho. 1 

The invaluable but misinterpreted section in the Ardley-Fritwell cuttings 

therefore enables a definite correlation between the Upper Estuarine Series 

and the Great Oolite succession of Oxfordshire to be made for the first time 

with a proper palaeontological and lithological backing. On Thompson's and 

Buckman's (unconscious) showing, the beds above and including the Estuarine 

Limestones in Northamptonshire are equivalent to the Hampen Marly Beds. 

Below, the Taynton Stone is well developed in the Fritwell cutting but has 

disappeared in Northamptonshire, where we are left with nothing but the 

'Lower Freshwater Beds' or Upper Estuarine Clay (3-18 ft.) and the Ironstone 

Junction Bed to correspond with it and all the strata beiow. The plane 

of unconformity below the Ironstone Junction Bed and Upper Estuarine 

Clay is the one already familiar, since Richardson's work in North Oxfordshire; 

but here there is another non-sequence directly above it, for strata 

equivalent to the Hampen Marly Beds, with the same Rhynchonellas and the 

same large oysters, seem to have overlapped the Taynton Stone and the 

Stonesfield Slate Beds entirely. (See fig. 53, p. 302.) 

VI. THE MARKET W'EIGHTON AXIS 2 

In North Lincolnshire the Great Oolite Limestone gradually becomes 

thinner northward, the last known occurrence being at Brigg, where 11J ft. 

of rock-bands separated by shales were penetrated in a boring, with 24 ft. of 

Blisworth Clay above and 24 ft. of Upper Estuarine Series below. The Blisworth 

Clay so far retains its normal characters, with beds of Ostrea sowerbyi 

at the top, but the Upper Estuarine Series becomes predominantly 

sandy. 

North of Brigg the outcrop is almost entirely obscured by alluvium and 

Boulder Clay to the Humber, except in the neighbourhood of Appleby Railway 

Station and Thornholme Priory, where the limestone has disappeared and 

the total thickness is much reduced. Thence northward to the Market 

Weighton Axis the Lincolnshire Limestone is separated from the Cornbrash 

by a single series of clays and sands, 20-30 ft. thick, which are continued 

in a narrow outcrop north of the Humber, past South Cave and New r bald, 

until they disappear under the Chalk near Sancton. 

The final reduction in thickness from about 60 ft. to 30 ft., and the disappearance 

of the limestone, take place quite suddenly in the 4 miles under 

alluvium between Brigg and Appleby Railway Station. The changes seem to 

follow a temporary expansion at Brigg, for, according to the accepted interpretation 

of the Brigg Boring, the Upper Estuarine Series below the limestone is 

24 ft. thick, while about Waddington and Redbourn, a few miles to the south, 

it has already been reduced to little more than 10 ft. The explanation of this 

may be that Brigg lies on the Caistor-Louth-Willoughby Axis of Kendall and 

1 Buckman gave to Thompson's Rhynchonellas from the Estuarine Limestone the names 

Burmirhynchia dromio and B. patula, but it must be remembered that he mistook the identity 

of R. concinna, fancying it to be a Lower Cornbrash species and calling it a Kallirhynchia 

(see p. 293, note 5). 

2 W. A. E. Ussher, 'Geol. North Lincolnshire', Mem. Geol. Surv., pp. 81-6; II. B. Woodward, 

1894, J.R.B., pp. 427-30; C. Fox-Strangways, 1892tJ.R.B.y pp. 259-60.


Versey, which we have seen was a synclinal axis of deposition in the Jurassic 

period and an anticline in the Cretaceous (see pp. 84—5). 

The correlation of the thin clays north of Brigg with their counterparts 

farther south is well-nigh impossible, owing to the absence of sections and the 

dearth of fossils. The question has been discussed by Ussher, who, although 

remarking that the clay is of about the same thickness as the Blisworth Clay 

south of Brigg and resembles it in appearance, points out that there is no 

proof that the Upper Estuarine Series is unrepresented. An overlap of the 

Blisworth Clay on to the Lincolnshire Limestone is therefore not proved. 

But there seems no doubt that it overlaps the Great Oolite Limestone; and in 

view of the correlation already traced between the Blisworth Clay and the 

Kemble Beds and Bradford Beds, and of the transgressive behaviour of these 

beds both eastward in the Southery Boring, Norfolk, and south-eastward 

under London (as will be seen in a later section of this chapter), an overlap here 

is to be expected. 

On the north side of the Axis the strata between the supposed Inferior 

Oolite and the Kellaways Rock as far as the Derwent comprise nothing but 

a thin and insignificant strip of sands, devoid of fossils. The sand, indeed, is 

sometimes difficult to distinguish from the Kellaways Rock, with which it is in 

contact. Whatever the exact age of this deposit, it provides clear proof of 

differential uplift along the Market Weighton Axis through almost the entire 

Great Oolite period. 


In the Yorkshire Basin deltaic conditions on a grand scale held sway during 

the Great Oolite period more completely than ever before. 1 Several times 

during the Inferior Oolite period the sea encroached northward over the 

delta-fans and laid down marine sediments and fossils all over Yorkshire; but 

during the formation of the Great Oolite there were no such interludes. As 

was pointed out in Chapters VIII and IX, the last marine episode, that of the 

Scarborough Beds, may have lasted from the hemera sauzei to the hemera 

zigzag—the time of formation of the Hook Norton Beds. Afterwards deltaformation 

continued, uninterrupted by any incursion of the sea, until the 

Callovian (Upper Cornbrash) Transgression. 

The series lends itself to subdivision into two broad lithological groups, 

a level-bedded group above, consisting predominantly of shales and mudstones, 

and a current-bedded group below, comprising false-bedded sandstones, 

mostly impure and silty in the upper part and changing laterally into shale, 

pure and sometimes very hard and siliceous in the lower part (the MOOR GRIT). 

The total thickness in the central area of the basin amounts to 200-220 ft. 

The only fossils besides plant-remains are casts of the freshwater bivalves 

1 The deposits formed during the Great Oolite period were known for more than half a 

century, since the days of the pioneers, Phillips and Williamson, as the Upper Sandstone 

and Shale, but in 1880 the Geological Survey introduced the term Upper Estuarine Series, 

which has now unfortunately become current. Since it was already preoccupied by Judd in 

1867 and by Sharp in 1870 for the Northamptonshire strata, with which probably only about 

one third of the Yorkshire division is to be correlated, the term has no legal status in Yorkshire. 

Further than this, 'estuarine' is a misnomer, for the deposits are deltaic like the Millstone Grit. 

In a consistent stratigraphical nomenclature the whole of the Yorkshire 'Estuarine Series' 

would need to be renamed, and there seems no reason why Upper, Middle and Lower 

Deltaic Series should not be applied.

'UPPER ESTUARINE SERIES': YORKSHIRE BASIN 313 

Unto distortus Bean and Unio hamatus Brown, found in some abundance in 

certain beds towards the base of the series in Gristhorpe Bay and about 

Scarborough. Although for many years their true affinitites were in doubt, 

they are now definitely considered to be Unios and are even said to be 

closely related to the modern Margaritana. 1 The plant remains are less 

common than in the Middle and Lower 'Estuarine' Series, and they are 

nearly all drifted. 

North of the Market Weighton Axis, both in the inland outcrop and on the 

coast, the series thickens gradually. It is thin and of little importance as a 

surface feature all through the Howardian Hills. Differentiation has already 

begun to show, however, for the upper portion is more shaly and the lower 

more sandy, in places almost a grit. 

The Moor Grit begins to make a feature in the south of the Hambleton 

Hills, sometimes covering large areas of moorland and running out in wide 

spurs, the ground covered with white siliceous blocks. Here the total thickness 

of the series increases to 100 ft. and then 200 ft., then dwindles temporarily 

to 100 ft. at the north end of the Hambletons, before regaining 200-220 ft. 

throughout the Clevelands and the moors both north and south of the Esk. 

On the Yorkshire Moors the Upper Estuarine Series forms barren ground. 

The more shaly upper part gives rise to a cold, wet surface, on w r hich the heather 

has a struggle for existence, while the hard Moor Grit supports but little 

soil. Locally the rock, which is much quarried for roadstone, is called White 

Flint. It is intensely hard, has a glassy surface, and is translucent in thin 

flakes. Under the microscope it is seen to be composed of sub-rounded grains 

of transparent colourless quartz, cemented by a secondary deposit of transparent 

crystalline quartz. The whole is so compact as to merit the name of a 

quartzite rather than a grit. 2 Towards the coast, as about Cloughton, it is 

more tractable and makes a good building-stone. 

The coast displays by far the finest sections in the county, but owing to the 

monotony of the series there is nothing to be gained by describing them here 

in detail. As in the inland outcrop, the thickness increases northward, from 

about 125 ft. in Gristhorpe Cliff to 200 ft. at Wheatcroft and farther north. 

The Moor Grit does not attain its characteristic development until the neighbourhood 

of Cloughton, and it is barely distinguishable south of Scarborough. 

The best sections of most of the series are seen in the cliffs from Cloughton to 

Scalby Ness, but the highest part of the even-bedded group is better shown 

at White Nab, south of Scarborough. 

Very interesting work on the conditions of deposition of the Upper Estuarine 

Series and the origin of the plant-beds has been done by Mr. Maurice Black. 3 

He has demonstrated that in the continuous cliff-sections the Upper 'Estuarine' 

Series shows the deltaic origin of the beds even more clearly than do the 

earlier 'Estuarine' Series. He likens the lower or false-bedded group to the 

foreset beds formed by a modern delta as it advances across a depression and 

the even-bedded group to the topset beds laid down after the depression has 

been nearly filled up. The whole sequence seems to indicate one major cycle 

1 J- W. Jackson, 1911, The Naturalist, pp. 104-7, 119-22. 

2 C. Fox-Strangways, 1892,J.R.B., p. 257, and for the three preceding paragraphs ibid., 

pp. 254-9, and pi. iv. 

3 M. Black, 1929, Q.J.G.S., vol. lxxxv, pp. 389-437; and 1928, Geol. Mag., vol. lxv, p. 301.

FIG. 55. Diagrammatic section of the Upper Estuarine Series, as exposed in the Yorkshire cliffs north of Scarborough, showing 'washout 

channels' (numbered A to G) and their relations to the strata which they cut. (From M. Black, 1929, Q.J.G.S., vol. ixxxv, p. 400, fig. 4.)

'UPPER ESTUARINE SERIES': YORKSHIRE BASIN 315 

of depression and elevation. Further he has pointed out a number of 'washouts' 

or filled-up channels similar to those described in the Lower Series by 

Hepworth, cut at various levels in the even-bedded group and sometimes 

down into the false-bedded group below (figs. 55-57). He explains these as 

the channels of streams which flowed over the surface of the delta. 

Mr. Black considers that, with the exception of a few subordinate beds containing 

only Equisetales and a few ferns, the majority of the plant-remains 

have been drifted; and since they have been sorted by water in common with 

other sedimentary materials, they do not represent natural floral assemblages. 

FIGS. 56 and 57. Details of channels C and D in fig. 55. (From 

M. Black, 1929, loc. cit., figs. 5 and 6, p. 403.) 

This applies to all the plant-beds containing ferns, conifers and Ginkgoales 

found in the level-bedded group and also to those with Ginkgoales and 

Cycads in the washouts. He contrasts the floras of these beds, presenting 

fragmentary and scattered specimens of different assemblages, with the 

Middle Estuarine Gristhorpe Plant Bed, in which all the parts of an individual 

are found together, not far from the position of growth, and even the most 

delicate structures are preserved. The sorting by mechanical means, by 

floating and by differential oxidation, all tending to destroy the more delicate 

tissues, may give an altogether misleading impression of the original assemblage. 

In this way many of the differences between the assemblages met with 

at different horizons, and especially those distinguishing the plant-beds of the 

Upper, Middle and Lower Estuarine Series, may be explained. 

Mr. Black notes that in the one locality (between Cloughton and Scalby 

Ness) where exposures are extensive enough to admit of the courses of the 

'washout' channels being mapped, the dip of the current-bedding shows that 

the water flowed along the channels from north to south. This hint as to the 

origin of the sediments and the location of the mouth of the river which formed 

the delta points in the same general direction as the conclusions long ago


reached by Sorby in studying the false-bedding in the Lower Estuarines. 

Both Sorby and Hepworth regarded the origin of the materials as in the northwest, 

where the deposits become more coarsely sandy. 1 The heavy minerals 

are still under investigation and have not yielded any positive results, except 

that they appear to have been re-derived from older sediments rather than 

first hand from an igneous or metamorphic region. 

VIII. THE HEBRIDEAN AREA 2 

On both sides of Scotland, in the Hebridean area and in East Sutherland, 

the same peculiar freshwater conditions prevailed in the Great Oolite period. 

At the top of the garantiana zone the marine succession is suddenly broken 

off and is not finally resumed until the Cornbrash. During the interval there 

were formed in the Hebridean area up to about 450 ft. of shales and mudstones, 

passing laterally into sandstones, of the same facies as the deposits in Eastern 

England. In the Hebrides the series is interspersed with beds of estuarine 

and freshwater shells; and on both sides of Scotland Unios have been 

found which Jackson believes are probably identical with the Yorkshire 

U. distortus Bean. 3 But towards the top there are marine oyster banks. 

Murchison originally termed the series in Western Scotland the Loch 

Staffin Beds, after a locality in the north-east extremity of Trotternish, Isle 

of Skye, but since the work of Judd it has generally been known as the Great 

Estuarine Series. (Map, p. 114.) 

Judd pointed out that the Great Estuarine Series of Scotland is developed 

in two main facies, an argillo-calcareous and an arenaceous; the former he 

likened to the Purbeck Beds of Dorset (for which previous to 1850 they were 

mistaken), the latter to the Hastings Sand. Very rapid lateral changes of 

facies and thickness take place in short distances. The series attains its 

greatest development (about 460 ft. according to the recent survey), 4 in the 

south of the area, in the islands of Eigg and Muck. It crops out from below 

the basalts on the north-west and the east coasts of Eigg, and on the south 

coast of Muck. Here it consists of three major divisions, a central mass of 

sandstones, according to Judd more than 500 ft. in thickness but according 

to the modern survey only 200 ft., sandwiched between two predominantly 

shaly series, the upper 50-60 ft. and the lower 200 ft. thick. In Mull only the 

very basal part of the series is known to occur in one small exposure. 

The upper shaly division consists of black shale, locally full of Cyprisy 

alternating with thin bands of argillaceous limestone. Some of the bands are 

crowded with 4 Cyrena' and Cyclas, others with Viviparus scoticus (Tate). 5 

The most conspicuous feature of the division, however, consists in thick 

1 H. C. Sorby, 1852, 'On the Direction of Drifting of the Sandstone Beds of the Oolitic 

Rocks of the Yorkshire Coast', Proc. Yorks. Phil. Soc., vol. i, pp. 111-13; and E. Hepworth, 

1923, Trans. Leeds Geol. Soc., pt. xix, p. 27. For fuller discussion see below, p. 580. 

2 Based on G. W. Lee, 1920, 'Mes. Rocks Applecross, Raasay and NE. Skye', pp. 52-7; 

C. B. Wedd, 1910, 'Geol. Glenelg, Lochalsh and SE. Skye', pp. 121-7; G. Barrow and 

A. Harker, 1908, 'Geol. Small Isles of Inverness', pp. 19-33; Mems. Geol. Surv. 

3 J. W. Jackson, 1911, The Naturalist, p. 119. 

4 Judd greatly over-estimated the thickness, his records showing a total of 850 ft. 

5 This species is entirely different from the Oxfordshire species, V. langtonensis (Hudl.), 

but associated with it in Skye is a form comparable with V. aurelianus Cossm., found in the 

department of Indre, but not in Oxfordshire.

'GREAT ESTUARINE SERIES': HEBRIDES 317 

oyster-beds, completely made up of the shells of Ostrea sowerbyi, which is 

known in all the literature as O. hebridica Forbes. 1 These are found wherever 

the upper part of the Great Estuarine Series occurs, all over the Western Isles, 

though in Strathaird, Skye, there are some 117 ft. of beds between them and 

the Callovian or Oxfordian as compared with only 20 ft. in Eigg. 

The central sandstone division consists mainly of white and grey, falsebedded, 

ripple-marked calcareous sandstones, often covered with sun-cracks 

or worm-tracks, and locally developing enormous doggers. The sandstones 

locally become coarser and contain stringers of little quartz pebbles, but 

usually the grains are very uniform in size; sometimes so much so that they 

give rise to musical sands. Plant-remains are abundant and in places they 

form thin coal-seams, as in Yorkshire. Other fossils are rare and, except for 

casts of Cyclas and l Cyrena\ unidentifiable. 

The lower shaly division resembles the upper and contains many of the 

same fossils, but towards the base it develops a series of conglomerates and 

shelly limestones, abounding in freshwater mollusca. It also yields numerous 

remains of ostracods, insects, fish, and reptiles, including Plesiosaurusy Acrodus, 

HyboduSy Lepidotusy Saurichthys and fragments of bones, vertebrae and teeth 

of crocodiles, deinosaurs, and pterodactyls. 

In the northern islands of Skye and Raasay this tripartite arrangement 

does not everywhere hold. In the promontory of Strathaird, in Southern 

Skye, where the thickness is 400 ft. and the distance from Eigg only 13 miles, 

the sandstone dies out and the two shaly divisions come together. In the north 

of the same island and the adjoining Isle of Raasay, however, although the 

total thickness diminishes to 250 ft., the sandstone returns and is as much as 

•50-100 ft. thick. 

The basalt plateaux of Strathaird and Trotternish have been responsible 

for the preservation of large areas of the Great Estuarine Series in Skye, and 

an unknown amount may also underlie the plateaux forming the western 

promontories of Vaternish and Duirinish, for small fragments crop out round 

the coasts at various points. Some of the chief exposures lie along the northeast 

coast of Trotternish in the line of cliffs between Bearreraig and Loch 

Staffin. This is the classic locality where the age of the beds was first proved 

by E. Forbes in 1850, during a cruise especially planned for the purpose. 

Here he found the estuarine strata, which Murchison had believed to be 

Wealden or Purbeck, cropping out from beneath the Oxford Clay. 2 

Perhaps the best sections of the series in the Hebrides are afforded by the 

south-western cliffs of Strathaird. North of Elgol the Great Estuarine Series 

succeeds the Inferior Oolite and dips away north-west towards the Cuillins, 

followed in orderly succession by the Oxfordian sandstones, representing the 

Oxford Clay discovered by Forbes at Loch Staffin. Since the sequence is 

typical of that developed all over Strathaird and is of the greatest interest 

for comparison with the development in other districts, it may be quoted in 

full. 

1 My original impression, formed in Skye, that these names referred to one and the same 

species, has been confirmed by the kind loan of a quantity of material by Mr. Malcolm 

MacGregor. In one locality he has found Rhynchonella cf. concinna and other marine fossils 

with the oysters. The name hebridica (E.Forbes, 1851, Q.J.G.S., vol. vii, p. 110) has priority 

over sowerbyi by two years, but in the interests of convenience it is desirable to deviate from 

the rules of nomenclature in this instance. 

1 loc. cit.

i9O 

LOWER OOLITES 

GENERAL SEQUENCE OF THE GREAT ESTUARINE SERIES IN S. SKYE 1 JT 

VI. Blue shaly marl with blue or white calcareous nodules: up to 30 or . . 40 

V. Viviparus scoticus Limestones. Blue fine-grained, smooth, argillaceous 

limestones or cementstones, weathering cream-coloured, containing 

gastropods, alternating with shales, fibrous carbonate of lime ('beef) 

and thin beds of calcareous sandstone . . . . . - 3 7 

IV. Black and blue shales and mudstones with occasional thin limestones: 

thickness doubtful, perhaps as much as . . . . . . 40 

III. Ostrea 4 hebridica' Beds. Calcareous shales or limestones crowded with 

O. 4 hebridica 9 Forbes (=0. sowerbyi Mor. and Lyc.) . . . 17 

II. 4 Cyrena 9 Limestones. Massive blue sandy and often crystalline limestones 

and calcareous sandstones, full of small lamellibranchs— c Cyrena 9 

auct. (=Neomiodon ?)—generally crushed together, alternating with dark 

shales and occasional bands of 'beef': sometimes a bed of Viviparus 

cf. aurelianus Cossmann occurs near the top. A b o u t . . . . 70 

I. *Cyrena 9 Shales. Black laminated shales with numerous beds of 'Cyrena 9 

throughout, and occasional thin bands of blue limestone and calcareous 

sandstone. About . . . . . . . . . 200 

Total . . . 404 

In Raasay and the adjoining coast of Trotternish the Great Estuarine Series 

exhibits some peculiar features, chief of which is the development of a true 

oil-shale at the base. The series is much thinner, not exceeding 250 ft., but 

there is nevertheless, as just mentioned, a partial return of the sandstone 

facies immediately above the oil-shale. The outcrop in Raasay is oblong in 

shape, occupying the highest part of the island, from the basalt caps of Dun 

Caan (Plate XIV) to the boundary fault which brings the Mesozoic rocks down 

against the Torridon Sandstone in the north. No sections are available showing 

the whole succession in unbroken continuity, but the Survey have been 

able to piece together sufficient information from scattered openings to give 

a general picture. 

The higher parts of the series, with the Ostrea sowerbyi Beds and Viviparus 

and 'Cyrena 9 , are well developed and together some 200 ft. thick. Below is a 

mass of white sandstone, 50 ft. thick in Raasay and in the north of Trotternish, 

but double that thickness farther south, near Holm. The lower part of the 

sandstone is carbonaceous and contains thin coal-seams as in Eigg and Muck, 

also Estherice and fish-remains. It passes downwards through increasingly 

argillaceous strata into the oil-shale. 

The Dun Caan Oil-shale is a true oil-shale, much resembling those of Carboniferous 

age worked in the Central Lowlands. Its thickness is 8-10 ft., and 

its yield of crude oil round about 12 gallons per ton. It follows conformably 

and gradually upon the clay of the garantiana zone, and it may therefore be 

as old as some part of the Upper Inferior Oolite. 

IX. EASTERN SCOTLAND 2 

(a) The Brora Coal-Field, Sutherland 

A series of similar beds, the counterpart of the Great Estuarine Series of the 

Western Isles, is found also in the same stratigraphical position on the east 

1 After Wedd, loc. cit. 

2 Based on G. W. Lee, 1925, in 'Geol. Golspie', pp. 74-9, Mem. Geol. Surv.

PLATE XIV 


Dun Caan and the east side of the Isle of Raasay. 

The top slopes are of Great Estuarine Series shales, capped by Tertiary basalt on Dun Caan 

(top left); the main cliff is Inferior Oolite sandstone, with a slope of Upper Lias below, and 

close to the sea on the right is the top of the Middle Lias (Scalpa Sandstone). The tumbled 

ground in front towards the left is a landslip. 


Fascally Coal Mine, Brora, Sutherland. 

The coal at the top of the Great Oolite Series is worked 250 ft. below river-level. The brickpit 

in the Brora Brick Clay (Lower Oxford Clay) is immediately behind and to the right of 

the derrick. Fascally Sandstone (Upper Oxford Clay) is seen in the river bank on right.

'GREAT ESTUARINE SERIES': EASTERN SCOTLAND 319 

coast of Scotland, in Sutherland and Ross. It is comparatively little known, 

however, for only about 60 ft. of the highest part is exposed. It is overlain 

abruptly by the marine equivalent of the Kellaways Clay, but how far downwards 

it extends is a matter of conjecture, for it abuts against a large fault, 

which throws down out of sight, not only the major portion of the Estuarine 

Series, but also any representatives there may be of the Inferior Oolite and 

the Upper and Middle Lias. 

The outcrop is small—only about J mile wide and 2 miles long—and is 

entirely covered with Drift. It strikes nearly W-E. under Dunrobin Mains 

and curves round to the north along the shore at Strathsteven, following a 

fault, which, after taking it out to sea for a short distance, brings it across the 

beach again, greatly narrowed, at a point south-south-west of Brora (map, p. 366). 

This last is the only locality at which it can be at all favourably seen, and there 

the exposure consists of little more than reefs covered by the sea at high tide. 

Most of the series consists of bands of sandstone and more or less sandy clay 

and shale, from at least one of which fifteen species of plants have been recorded 

by Dr. Stopes 1 and Carruthers. The highest part consists of 26 ft. of 

laminated, black, bituminous shales, at the top of which is the well-known 

Brora Coal. The bituminous shales contain Estheriay Unio distortus Bean and 

'Cyrena' cf. jamesoni Forbes (both Hebridean species), and three other species 

of 'Cyrena', together with such marine forms as Isognomon, Pleuromya and 

'Potamomya\ Judd also recorded scales and teeth of fish, including Lepidotus, 

Semiotus, Pholidophorusy Hybodus and Acrodus. 

The Brora Coal main seam averages about 3 ft. 6 in. in thickness, and there 

are several thin and impersistent seams in the underlying shales. According to 

Dr. Lee, 

'The coal is black, lustrous and brittle, breaking into small fragments. It contains 

a high percentage of disseminated pyrites, besides a lenticular band of solid pyrites 

towards the middle of the seam. The ash content is also very high, a large bulk being 

left when burnt. Spontaneous combustion ... is of frequent occurrence, both in 

the mine and in the waste heap. The water from the working galleries is so acid that 

special arrangements had to be made to drain it directly into the sea, as, when drained 

into the river, it killed the fishes.' 2 

The only mine at present working is at Fascally in the valley of the River 

Brora (Plate XIV, and map, p. 366). About 30 tons daily are raised for use in 

the village and the immediate neighbourhood. 

According to Sir John Flett the first mine was opened in 1598 by the 

Countess of Sutherland, and this was followed by the sinking of four or five 

new pits by the Earls of Sutherland in the early part of the seventeenth century. 

The workings were never more than barely remunerative and they have been 

frequently abandoned and reopened only to be again abandoned. This is 

attributed to several objectionable properties, chief of which are a sulphurous 

smell, a high percentage of light ash which blows all over the room when the 

coal is used domestically, and liability to spontaneous combustion owing to 

the presence of the pyrites. The surviving mine was opened in 1810, and it 

1 The title of Dr. Marie Stopes' paper, The Flora of the Inferior Oolite of Brora (Sutherland) 

is misleading, since the beds are likely to be much more nearly equivalent in age to the upper 

part of the Great Oolite Series. 

2 G. W. Lee, 1925, loc. cit., p. 75.


reaches the coal at a depth of 250 ft. Some of the earlier openings were surface-workings 

at the only outcrop, on the beach south-west of Brora, but the 

coal can no longer be seen there. Another mine was sunk in 1872 at Strathsteven, 

near the shore, 2 miles south-west of Brora, but this failed owing to 

the coal being cut out by a fault. 1 

(b) Ross-shire 

Small remnants of the highest part of the Estuarine Series have been 

described by Lee at Port-an-Righ, south of Balintore, Ross-shire, at the south 

end of the section which is dealt with in the next chapter in connexion with 

the Oxford Clay. The Brora Coal is represented by a carbonaceous layer 

4 in. thick, beneath which can be seen some 9 ft. of shales and sandstones in 

discontinuous section. 'Cyrena* jamesoni and Isognomon are recorded. 

X. KENT 2 

In view of the marked transgression of the Great Oolite at the outcrop 

from the Oxfordshire-Northants border eastward and north-eastward to the 

Humber, it is not surprising to find the formation transgressive also to the 

south-east, in Kent. The Kent borings have shown, in fact, that the Great 

Oolite period witnessed the most important transgression of Jurassic times 

against the southern border of the London landmass. The series soon overlaps 

the thin sandy representative of the Upper Inferior Oolite (p. 246) upon 

which it rests in the most south-westerly borings, at Brabourne and Dover, 

overstepping on to Upper Lias at Fredville, on to Middle Lias at Chilham, 

Harmansole, &c., on to Coal Measures still farther to the north and east, at 

Oxney, Bere Farm, Tilmanstone, &c., and eventually on to Silurian in the 

extreme north, at Bobbing. The Great Oolite Series therefore spreads a 

considerable way beyond any of the earlier Jurassic rocks before being itself 

overstepped by the Cretaceous, and there is a strip of country under which it 

alone separates the Cretaceous rocks from the Palaeozoic platform (fig. 8, 

p. 52). 

At the same time important lithological changes take place and the series 

thins out piecemeal from 150 ft. at Brabourne and 144 ft. at Chilham to 82 ft. 

at Bobbing in the north and 51 ft. at Oxney in the east. 

From the detailed records and excellent palaeontological data published by 

the Survey, it is interesting to attempt to distinguish which of the subdivisions 

present at the outcrop in the west can be recognized. 

All the borings (excepting that at Brabourne, to be mentioned later) show r ed 

three main lithological divisions: at the top 7-18 ft. of clays and limestones of 

Forest Marble facies and grouped as 'Forest Marble'; in the middle a thick 

mass (40 ft. to over 100 ft.) of predominantly white oolitic limestones; and at 

the base a very variable thickness of sands, sandy limestones and sandy clays. 

Forest Marble, 7-18 ft. 

The presence of beds classified according to their lithological and palaeontological 

facies as 'Forest Marble' in all the borings and the relative uniformity 

1 J. S. Flett, 1922, 'Special Reports, Mineral Resources', xxiv, Mem. Geol. Surv., pp. 32-6. 

2 Based on Lamplugh, Kitchin and Pringle, 1923, 'The Concealed Mesozoic Rocks in 

Kent'; and Lamplugh and Kitchin, 1911, 'The Mesoz. Rocks in some Coal Explorations 

in Kent', Mems. Geol. Surv.

GREAT OOLITE SERIES: KENT 321 

of their thickness is of interest, for it indicates that the north-easterly attenuation 

of the Great Oolite Series as a whole is not due to overstep by the Cornbrash. 

Rather it is a piecemeal overlap and thinning against a shore-line. 

Another matter of interest is the small thickness of the 'Forest Marble' in 

all the borings: no higher reading than ?i8 ft. was obtained anywhere. This 

suggests comparison with East Oxfordshire and Bucks., and as there were well 

over a dozen borings and no trace of Bradfordian fossils was found in any one 

of them, it seems likely that the 'Forest Marble' is older than the Bradford 

Clay; that is, is Kemble Beds, as in most of East Oxfordshire and Bucks. 

Further, it would appear that at least in some of the borings part of the 'Forest 

Marble' belongs to the Fimbriata-waltoni Beds, for at Tilmanstone and at 

Harmansole the Survey remarked on the similarity of the greenish-black, 

shelly and lignitiferous clays to those at Blackthorn Hill and Ardley railwaycuttings 

near Bicester. 1 With this suggestion the occurrence of Astarte fimbriate*, 

Lyc., Epithyrids, and a number of other fossils not usually found in the 

Wychwood Beds agrees. There seems, therefore, to be a non-sequence below 

the Cornbrash all over Kent, just as over the more northerly Eastern Counties. 

Great Oolite Limestones, 40-100 ft.+ ? 

As a whole the Great Oolite Limestones are rather featureless and are not 

susceptible to subdivision. For instance at Harmansole the record is obliged 

to treat as a single bed 79 ft. of 'creamy white and bluish-grey, finely oolitic 

limestones, evenly bedded, and shelly in places'. This sounds all like White 

Limestone, but below there are only 7 ft. of sandy beds, and then the Middle 

Lias. It is probable, therefore, that it also contains representatives of the 

freestones below the White Limestone—the 'Lower Division' of the Great 

Oolite. At one place, Tilmanstone, there are indications of Hampen Marly 

Beds below obvious White Limestone. This record is so interesting that it 

is worth repeating with suggested correlations, as illustrative of the Kent 

Great Oolite. (See next page.) 

The record of Ornithella, suggestive of the Ornithella Beds of Chedworth, 

is especially interesting when considered in conjunction with records of 

Burmirhynchia hopkinsi (Dav.) at Dover 2 and of Solenopora jurassica at Bobbing 

3 —all three especially characteristic of the middle and lower part of the 

White Limestone in the Chedworth cuttings. The clays coming below, crowded 

with Ostrea sowerbyi, strongly suggest the Hampen Marly Beds. 

As is to be expected, there are some elements in the Great Oolite fauna 

which are common to the Boulonnais but foreign to the inland outcrop in 

England. Of such the most noticeable is Trigonia clavulosa Rig. and Sauvage, 

obtained rather low down in the series in several of the borings. 

Fuller's Earth and Chipping Norton Limestone. 

The most south-westerly of all the borings touching Great Oolite, that at 

Brabourne, passed through 13 ft. of'Forest Marble', then 114 ft. of limestones, 

the lowest 33 ft. becoming somewhat sandy, and finally through 23 ft. of 

'dark grey or bluish calcareous shales', . . .'passing down into 44 ft. of greyblue, 

somewhat muddy oolitic limestone of medium texture . . . apparently 

unfossiliferous'. This last, which was queried as Inferior Oolite, rested upon 

1 1923, loc. cit., pp. 116, 143. 

3 1923, loc. cit., p. 160. 

2 1911, loc. cit., p. 140.


ths Upper Lias clay. 1 The grey shales unfortunately yielded only a few illpreserved 

fragments of Astarte, Oxytoma, &c. and nothing to connect them 

definitely with the Fuller's Earth. This is the only boring in Kent that has 

of 

TILMANSTONE BORING. 

Suggested Correlation. Recordr 

[Cornbrash above.] ft. in. 

KEMBLE BEDS 

he { FIMBRIATA- 

K a cord I WALTONI BEDS 

7 ft. 

G i eat 

Oolite 

of 

Record 

6k* ft. 

WHITE LIMESTONE 

(Ornithella Beds of 

Chedworth represented 

here ?) 

HAMPEN MARLY 

BEDS 

Whitish limestones, somewhat clayey in places. 5 o 

Brown, black and greenish-black clays, as at 

Blackthorn Hill and Ardley, with several 

pale fossiliferous bands '. . . . 2 

Coral and fossil bed: greyish-white earthy 

limestone; Isastrcea, Thamnastrcea, Montlivaltia, 

Epithyris [oxonica], Parallelodon, Lima 

cardiiformis, &c., &c. . . . . 

W 7 hite and creamy oolitic limestones with 

marly bands . . . . . . 

Dark grey clayey limestones; Rhynchonella spp. 

(concinna group), Ornithella sp., Nerinea 

eudesii, AT. sp., Natica spp., Pholadomya spp., 

Lucina bellona, Lima cardiiformis, &c. . 

Limestones, with a thin band of dark clay full 

of Ostrea sowerbyi . . . . . 

Soft dark brown shelly clay full of Ostrea 

sowerbyi . . . . . . 

Hard grey limestone. All shells dissolved out 

of fossiliferous band in middle of bed; 

Trigonia clavulosay T. painei, Parallelodon, 

Gervillia monotisy G. subcylindrica, 4 Terebratula* 

sp., Nerinea sp., See. 

CHIPPING NORTON Sands, with some bands of clay 

LIMESTONE 

15 8 

19 3 

given any indication of the Fuller's Earth facies so characteristic of Dorset and 

Somerset. 

Farther north and east the Great Oolite Limestones are underlain by sands 

and sandy limestones which, in their lithology and palaeontology and their 

unconformable relations to the underlying strata, correlate w : 'h the sandy 

facies of the Chipping Norton Limestone (the Hook Norton and Sw T erford 

Beds). In some places, such as at Harmansole, where they rest on Middle 

Lias, there is at the base a pebble-bed composed of sub-angular detritus of 

limestone; at others, where the sands repose on a fresh surface of Coal 

Measures, as at Tilmanstone, they are composed almost entirely of quartz, 

the grains ranging up to the size of a marble. At Bobbing, where the Silurian 

is the bed-rock, the base contains slate pebbles. 3 

An invaluable link between these sandy basement-beds and the Hook 

Norton Beds of Oxfordshire is the occurrence of Trigonia signata Ag. at 

Elham and Snowdown. On the same horizon, however, there are foreign 

elements, the most conspicuous being Rhynchonella lotharingica Haas, which 

is rather abundant in some of the borings. 

1 1911, loc. cit., p. 48. 

2 1923, loc. cit., pp. 140-1; some of the fossils and notes added from pp. 143-5. 

3 1923, loc. cit., pp. 113, 144, 153.

GREAT OOLITE SERIES: LONDON DISTRICT :>3 

XI. THE EASTERN MARGIN OF THE LONDON LANDMASS 

The very pronounced transgression in Great Oolite times proved by tho 

borings in Kent was long ago known round the eastern margin of the Lond< r 

landmass, for Great Oolite had already been found under Richmond and 

Streatham Common in Surrey and at Meux's Brewery in the Tottenham 

Court Road, in the heart of London. Like the most northerly and easterly 

of the Kentish borings to penetrate any Jurassic rocks, these London borinrs 

lie in the belt where nothing but Great Oolite intervenes between the Palae-.; 

zoic platform and the Lower Greensand (see Dr. Rastall's map, fig. 6, p. 45). 

It is interesting to note that two of these borings, those at Richmond ana 

Tottenham Court Road, disclosed richly fossiliferous Bradford Beds. Indeeu. 

it was owing to the highly distinctive assemblage of brachiopods, polyzoa anc 

other fossils brought up from these beds that the presence of the Great Oolite: 

Series in so unexpected a position was recognized beyond possibility of douh-r 

as early as 1880. J. W. Judd sent collections of brachiopods to Davidson arvJ 

of polyzoa to Vine—all 'exquisitely preserved'—without telling the specialise 

whence they had been obtained. Both reported them to be of the age of tL 

Bradford Clay. The brachiopods and other fossils included Dictyothyr 

co arc tat a, Epithyris bathonica, Cidaris bradfordensis and Apiocrinusy and Via 

recognized fourteen species of Bradfordian polyzoa. 1 

The most satisfactory record was obtained at Richmond, where the secti< 0 

was as follows (greatly condensed) : 

RICHMOND BORING 

WYCHWOOD BEDS f Oolitic limestones, some of the bands with many ft. / - 

and J foraminifera . . . . . . 53 6 

BRADFORD BEDS 1 Bradford Clay: blue clay with bands of limestone and 

57 ft. 1 many Bradfordian fossils . . . . . 3 

WHITE LIMESTONE Oolitic and shelly limestones, with 6 in. marly bed at 

17 ft. base . . . . . . . . 17 

'Fine-grained oolitic limestone with much pyrites, 

PTAYNTON STONE 

and 

STONESFIELD 

SLATE BEDS 

13 ft. 

becoming sandy lower down; and at the base a 

fissile calcareous and micaceous sandstone, like 

Stonesfield Slate; Acrosalenia and other fossils . 9 o 

Oolitic limestones with shell-fragments, Ostrea 

sowerbyi, &c., and a few grains of quartz and particles 

of anthracite [derived from Coal Measures] 

L in basal 6 in. . . . . . . . 4 0 

The difference between this record and those in Kent, with their small thickness 

of' Forest Marble', and that apparently all pre-Bradfordian, is most striking. 

The Great Oolite in the Streatham boring 2 seems to have been more 

conformable to the Kentish type. No Bradfordian fossils were encountered, 

and only 38^ ft. of Great Oolite strata were present, or only 8 ft. more than the 

amount below the Bradford Clay at Richmond. Within 8i ft. of the top an 

oyster queried as O. acuminata was recorded, and between 8 J and 11 ft. from 

the top were 'sandy rock' and 'hard grey calcareous sandstone', by which 

Woodward was reminded of the Stonesfield Slate of Througham near Bisley 

1 J. W. Judd, 1884, Q.J.G.S., vol. xl, pp. 724-64. As Davidson reported that the Ten 

bratula maxillata was the same as those in the Bradford Clay, it must have been E. bathonica. 

2 W. Whitaker, 1889, Rept. Brit. Assoc. for 1888, p. 656; and H. B. Woodward, 18c.,, 

J.R.B.t p. 362.


(Glos.). Below this the remainder of the beds (27\ ft.) were mostly clay, with 

occasional bands of limestone, and Ostrea acuminata towards the top. These 

facts suggest that the Greensand here rests on Stonesfield Slate Beds and 

Fuller's Earth. There is more affinity between the borings at Streatham and 

Brabourne than between those at Streatham and Richmond or Tottenham 

Court Road. Apparently the Fuller's Earth dies out towards the north just 

as along the outcrop in the West of England; though the complete disappearance 

of over 27 ft. of it between Streatham and Richmond is remarkably abrupt. 

The nearest connecting links between these London borings and the outcrop 

are those at Calvert, south of Buckingham, on the Oxford Clay. Although 

so much nearer the outcrop, they may be most appropriately considered here 

in connexion with the other borings. 

The succession at Calvert agrees with the Kentish succession in the absence 

of the Bradfordian fauna, but the Forest Marble is at least twice as thick 

(38 ft. 9 in.). The record agrees especially well with that at Tilmanstone, 

described on p. 322,for there is a thick development of Hampen Marly Beds— 

in fact the thickest known. Two marked non-sequences are shown: at the top 

the Lower Oxford Clay with Kosmoceras rests directly on the Forest Marble, 

without the intervention of any Cornbrash or Kellaways Beds; at the bottom 

the Great Oolite Series rests directly on the lower part of the Middle Lias— 

the same transgression as that found in Kent, Surrey, and Middlesex, and 

more marked than at the outcrop. As there is some doubt as to what part of 

the series is represented by the transgressive bed at the bottom, a brief condensation 

of the record may be given, with the interpretation now suggested. 

(See next page.) 

In their interpretation Prof. Morley Davies and Dr. Pringle bracket the 

lowest 7 ft. 6 in. as Chipping Norton Limestone. They admit that this is 

suggested on purely lithological grounds, and apparently the chief reason is 

that a part of the stone when examined microscopically resembled the Hook 

Norton Beds of Sharp's Hill. 1 But as the borings are only 7 miles from the 

Great Oolite outcrop, they must be compared with the sequence at the 

neighbouring outcrop; and there are complete sections only 10 miles away, 

in the Ardley-Fritwell railway-cuttings. 

The presence of Hampen Marly Beds in force at Calvert agrees with the 

Ardley-Fritwell cuttings and also with the nearest other exposures, in the 

Evenlode Valley; but at Calvert the beds are much thicker—indeed even 

thicker than in the North Cotswolds—and they seem to have thickened at 

the expense of the White Limestone, which is unusually thin. In the Ardley- 

Fritwell cuttings the Hampen Marly Beds rest on well-developed Taynton 

Stone, with a condensed representative of the Stonesfield Slate Beds below, 

and as we know the Taynton Stone to be itself transgressive (see p. 302) it is 

hardly likely to have been overlapped entirely by the Hampen Marly Beds in 

so short a distance (no such overlap being known anywhere at the outcrop). 

It is more probable that the Taynton Stone and possibly Stonesfield Slate 

Beds here overlap the lower parts of the series on to the Lias. The fossils in 

the basal limestones are in harmony with this view 7 —fragments of broken 

Rhynchonella, Terebratula, Ostrea sowerbyi and O. aff. acuminata—not at all 

suggestive of Chipping Norton Limestone. The chief objection to correlating 

1 A. M. Davies, 1913, Q.J.G.Svol. lxix, pp. 317, 19.

GREAT OOLITE SERIES: CALVERT BORING 325 

anything in the Calvert boring with Chipping Norton Limestone is that if any 

strata of that age were present they should, by analogy with all the exposures 

on the neighbouring outcrop, be in the facies of White Sands. The locality 

is well to eastward of Turweston, where the Hook Norton Beds are entirely 

overlapped (see p. 303 and fig. 38, p. 207), and so nothing but White Sands (if 

Interpretation 

now suggested. 

?Trace of Wychwood 

Beds (perhaps). 

KEMBLE BEDS 

FIMBRIATA-WALTONI 

BEDS 

Together 38 ft. 9 in. 

WHITE LIMESTONE 

12 ft. 

HAMPEN MARLY BEDS 

42 ft. 3 in. 

TAYNTON STONE and 

PSTONESFIELD 

SLATE BEDS 

12 ft. 9 in. 

CALVERT BORING 

Summary of Record after 

A. Morley Davies and J. Pringle. 1 

Oolitic 'Forest Marble' limestones, with a 3-in. ft. in. 

band of bright green clay . . . 25 6 

Grey marly clays, passing down into brown and 

greenish clays, with a bed of green sandstone 

and a hard band of grey limestone . . 16 9 

'Limestones; top bed compact, bottom bed with 

Epithyris [oxonica] . . . . . 1 2 0 

Dark grey marly clay full of Ostrea sowerbyi and 

Rhynchonella concinna; 6 in. of grey marl at top. 3 0 

1 Grey earthy limestone . . . . . 5 0 

Soft dark grey sandy shales and marls; no core seen 25 9 

Grey limestones and marls . . . . 6 6 

Grey marly clay full of O. sowerbyi and R. concinna 2 0 

Grey limestone with an Ostrea band near top . 3 6 

Dark grey marl . . . . . . 3 

Grey thinly-bedded limestone with lignite fragments 

. . . . . . . 1 6 

Yellowish oolitic limestone . . . . 2 0 

Sandy limestone with abundant ooliths and fragments 

of Rhynchonella, Terebratula, Ostrea 

sowerbyi and O. aff. acuminata . . . 5 0 

Yellowish false-bedded oolitic limestone . . 6 

[Middle Lias below.] 

anything at all) should be left. If the thread of pp. 303-5 be followed on a map, 

it will readily be seen that the occurrence of oolitic limestones down to the 

surface of the Lias in the Calvert boring can almost be taken as a certain indication 

that nothing of the age of the Chipping Norton Limestone is present. 2 

One other place where borings have proved the Great Oolite Series to 

overstep eastward against the London landmass is much farther north, at 

Southery, Norfolk, midway between Newmarket and King's Lynn, near the 

eastern edge of the Fens. Here only 8 ft. of rock of Forest Marble facies was 

found beneath the attenuated Cornbrash, resting again on Middle Lias. 3 The 

beds consisted of dark, greenish-black, shelly clays, enclosing 3 ft. 3 in. of 

hard, bluish-grey, earthy limestone. Insufficient fossils were recognized for 

the strata to be dated more accurately, but Bradfordian forms were definitely 

absent. Lithologically the description of the rocks suggests the Fimbriatawaltoni 

Beds. 

1 A. M. Davies and J. Pringle, 1913, Q.J.G.S., vol. lxix, pp. 310-19. 

2 At the time when the Calvert boring was described, of course, sufficient detailed work on 

the outcrop had not been done to enable satisfactory comparison to be made. 

3 J. Pringle, 1923, Sum. Prog. Geol. Surv.iox 1922, pp. 129-31.

CHAPTER XI 

CORNBRASH 

Ammonite Zones. Brachiopod Zones. StrataI Divisions. 

Macrocephalites 

macrocephalus 

Clydoniceras 

discus 

Rhynchonelloidea 

cerealis Buck, 

group 

Kallirhynchia 

yaxleyensis (Dav.) 

group 

Microthyris 

lagenalis (Schloth.) 

Microthyris 

siddingtonensis 

(Dav.) 

Ornithella 

obovata (Sow.) 

Cererithyris 

intermedia (Sow.) 

Upper 

Cornbrash 

Lower 

Cornbrash 

THE Cornbrash, like the Upper Inferior Oolite, is a transgressive deposit 

which on stratigraphical grounds demands description in a separate 

chapter. If this be thought insufficient reason for alienating it from its parent 

formation, the Great Oolite Series, then justification is readily forthcoming 

from a study of the palaeontology. Eighty years ago Lycett suggested that 

the Cornbrash should be ranked as equal in importance to the whole of the 

rest of the Great Oolite Series; he wrote: 'Basing our generalizations 

upon the zoological characters of the deposits, we are led to the conclusion 

that the Great Oolite should be arranged into two stages or faunafs], and that 

all the subordinate groups of deposits older than the Cornbrash constitute 

a single and lower stage of the formation.'1 This is not the whole story, however. Although the Cornbrash as a whole 

is transgressive, there is a still greater transgression and a far greater change 

of fauna in the middle of the formation. William Smith noticed this before 

1816, for he stated, 'The Cornbrash, though altogether but a thin rock, has 

not its organized fossils equally diffused, or promiscuously distributed. The 

upper beds of stone which compose the rock, contain fossils materially 

different from those in the under.'2 This remarkable observation was overlooked 

for more than a century, while authors preferred to speak of the 

Cornbrash as if it were a single homogeneous stratum, indivisible, and 

remarkable only for its wide distribution and lithic uniformity. 

In reality the Cornbrash consists of two essentially distinct parts, an Upper 

and a Lower, which differ widely in lithology as well as in their fauna. 

The Lower Cornbrash is characterized by the ammonites Clydoniceras 

discus (Sow.), C. hochstetteri (Oppel) and other allied forms, and can generally 

be subdivided into two brachiopod zones, the lower characterized by Cererithyris 

intermedia, the upper by Ornithella obovata. It is linked by these genera 

and by most of its lamellibranch fauna to the Great Oolite Series, though there 

is relatively seldom specific identity (except with the lamellibranchs of the 

Fuller's Earth Rock, see pp. 256-7). The richest profusion of lamellibranchs 

occurs at the top of the obovata zone, where there is usually an ASTARTE- 

TRIGONIA BED, crowrded with Astarte hilpertonensis Mor. & Lyc., Trigonia 

1 J. Lycett, 1857, The Cotteswold Hills, p. 84. 

2 William Smith, 1816, Strata Identified by Organized Fossils, p. 25.

THE CORNBRASH 327 

angulata Sow., T. rolandi Cross, Entolium rhypheum (cTOrb.) and the buttoncoral, 

Anabacia complanata. Besides the zonal brachiopods, Rhynchonellids 

of the group of Kallirhynchia yaxleyensis (Dav.) are especially characteristic. 

The lithology of the Lower Cornbrash varies from brown or grey marly 

rubble to massive beds of blue-hearted limestone, but it nearly always stands 

in marked contrast with the Forest Marble below and there is seldom any sign 

of passage between the two. Although it is only rarely that pebble beds or 

other signs of erosion are perceptible at the base, the change of lithology is 

nearly everywhere abrupt and complete, and observation of a long stretch of 

outcrop shows that there is also gradual overstep of the Forest Marble. 

The Upper Cornbrash is less variable in lithic characters, consisting usually 

of sandy limestones or ferruginous sandy marls with doggery limestone bands, 

and occasionally massive beds of hard, pink or purplish-centred limestone 

weathering into flags. Palaeontologically it provides a much more marked 

contrast with the Lower Cornbrash than does the Lower Cornbrash with the 

rest of the Great Oolite, for its fossils are essentially of Callovian aspect. 

Instead of the Bathonian genus Clydoniceras, which seems to have become 

totally extinct, we find the Callovian family Macrocephalitidce (Macrocephalitesy 

Kamptocephalites, &c.). The Bathonian Ornithella and Cererithyris have 

disappeared, giving place to the Callovian brachiopod genus MicrothyriSy of 

which two zones can be recognized, those of M. siddingtonensis below and M. 

lagenalis above; while the abundant Kallirhynchias of the Bathonian have been 

replaced entirely by the little Rhynchonelloidea ccrealis Buck., closely allied to the 

Rh. socialis of the Kellaways Beds. It is impossible to distinguish the specimens 

of M. lagenalis by external characters from those of the Kellaways Rock. 

With the new brachiopods enters a fresh suite of lamellibranchs, such as 

Trigonia cassiope d'Orb., T. elongata Sow., T. scarburgensis Lyc., and the 

oysters O. (Liostrea) undosa Phil, and O. (.Lopha) marshii Sow. 

At the base of the Upper Cornbrash there is sometimes a pebble-bed marking 

the junction with the Lower Division, and the line of demarcation is nearly 

always plainly discernible. Upwards, on the contrary, the passage into the 

Kellaways Beds is more or less gradual. The logical line of separation 

between the Bathonian and Callovian stages should therefore, beyond any 

question, be drawn between the Lower and Upper Cornbrash. In the South 

of England this line marks one of the most easily detected conformable transgressions 

in the Jurassic System, while northwards, in Yorkshire, it becomes 

very conspicuous. There the Upper Cornbrash is spread over the unfossiliferous 

top of the Upper Estuarine Series as the first stratum of the marine 

Upper Jurassic succession. 

Had d'Orbigny realized that neither in France nor in England do the 

Macrocephalitan and the Clydoniceratan faunas occur together, he would 

not have included the macrocephalus zone in his Bathonian Stage. Oppel regarded 

it as Callovian; but he did not realize that Macrocephalites occurs in 

the Cornbrash, for he chose as type-locality Stanton and Chippenham, where 

only Lower Cornbrash is developed. He admitted failing to find M. lagenalis 

(his zone-fossil for the Cornbrash) in the Chippenham district, but he found 

it at another place in Wiltshire; and, little suspecting that it came out of 

macrocephalus beds, he made the lagenalis zone Bathonian. 1 

1 A. Oppel, 1856-8, Die Juraformation, p. 456; and see also p. 509.


I. THE DORSET—SOMERSET AREA 1 

The Cornbrash attains its greatest thickness of 25-30 ft. in Dorset, and of 

this one-third belongs to the Lower and two-thirds to the Upper Division. 

The complete sequence is exposed in the low cliffs of the Fleet backwater, 

at Chesters Hill, near Abbotsbury Swannery. The greater part of the thickness 

consists of alternate bands of cream-coloured argillaceous marl and hard 

concretionary or doggery limestone, most of it belonging to the siddingtonensis 

zone, and the topmost beds to the lagenalis zone. Large gerontic Macrocephalitids 

may sometimes be found (map, fig. 61, p. 342). 

The Lower Cornbrash consists of 4 ft. of rubble full of fossils belonging to 

the obovata zone, with at the base 3 ft. of hard pinkish limestone of the intermedia 

zone. The usual fossils, Pseudomonotis echinata (Sow.), Chlamys vagans 

(Sow.), Chi. hemicostata (Mor. & Lyc.), Pholadomya deltoideay Pleuromya decurtata, 

Nucleolites clunicularis, &c., abound here, as at almost every exposure 

of Lower Cornbrash. 

The section is repeated by a fault about three-quarters of a mile to the 

south-east along the shore, and there the Lower Cornbrash has expanded to 

about 11 ft., of which 10 ft. are assigned to the obovata zone. This furnishes 

an example of the great variability in thickness of the zones in short distances, 

a feature characteristic all over England. The palaeontological vagaries in the 

Cornbrash, resulting from the local distribution of colonial brachiopods, are 

well illustrated in two inland sections not far from the coast. In one, at Swyre, 

the Lower Cornbrash is capped by a band crowded with Kallirhynchia multicosta 

Douglas and Arkell, a species met with only rarely at two or three other 

Dorset localities, while at East Fleet there is another quarry containing only 

an occasional Kallirhynchia, but instead, hundreds of specimens of Ornithella 

classis Dougl. and Ark., a species hitherto found in no other district, and 

rare even in the coast sections. Similarly, at Yetminster in North Dorset, on 

the other side of the Chalk Downs, the Lower Cornbrash contains a band 

abounding in Ornithella rugosa Dougl. and Ark., which is very rare elsewhere, 

while at Corscombe, near by, the largest Cornbrash Rhynchonellid, 

Kutchirhynchia idonea Buckman, makes its only known appearance in 

England, in a thin seam of marl. 

All these occurrences are in the obovata zone of the Lower Cornbrash, and 

they are the exception rather than the rule. Usually the fauna of this zone is 

monotonously typical and may be recognized at a glance. 

The dominance of the Upper Cornbrash with its thick sandy and marly 

beds and bands of concretionary (doggery) limestone is continued throughout 

Dorset and into the southern part of Somerset, being well seen at Corscombe, 

Closeworth, Holwell, Stalbridge and Wincanton. In the same district, in 

quarries at Yetminster and Bishop Caundle, the intermedia zone is also seen 

at the maximum development attained in England, namely 5-6 ft. of hard, 

massive, blue- or inky-hearted limestone, having much of the appearance of 

Kemble Beds. 

At Cards Farm near South Brewham, on the other hand, and at South 

Cheriton, the intermedia zone has shrunk to its usual thickness, not exceeding 

1 Based on J. A. Douglas and W. J. Arkell, 1928, 'The Stratigraphical Distribution of the 

Cornbrash', Part I, Q.J.G.S., vol. lxxxiv, pp. 143-55.

£ HANDTHORPE SLEAFORD SUDBROOKE APPLE8V MARKET HOWARD I AN KEPWICK YORKSHIRE SCAR60RO 

Z WEIGHTON HILLS MOORS 

£ 

OBOVATA ZON E 

FIG. 58. Diagrammatic longitudinal section of the Cornbrash along the outcrop from Abbotsbury on the Dorset coast to Scarborough on the Yorkshire 

coast, showing the changes in thickness and the distribution of the brachiopod zones. The boundary between Lower and Upper Cornbrash is reduced 

to horizontality. Horizontal scale, 1 in. = 22J miles; vertical scale, 1 cm. = 18 ft.


2 ft., and the Upper Cornbrash has diminished to a thin bed of marly rock with 

M. lagenalis. Here, and henceforth for many miles, until beyond Malmesbury 

in North Wiltshire, the principal role is taken by the obovata zone. At South 

Cheriton and South Brewham it is from 7 to 8 ft. thick, consisting of the 

Astarte-Trigonia Bed at the top and flaggy to massive, white, poorly fossiliferous 

limestones below. These limestones reach their maximum thickness 

at Corston, Wilts., from which they take the name CORSTON BEDS. The 

Astarte-Trigonia Bed at South Brewham is a remarkable repository of perfectly 

preserved lamellibranchs, from which Sowerby figured the type 

specimen of Trigonia angulata. 

II. THE MENDIP AXIS (FROME DISTRICT) 

Two of the finest sections of the Cornbrash in England were opened up 

in 1931-2 in the cuttings for the Great Western Railway's new loop-line to 

avoid Frome Railway Station. The cuttings have exposed the whole of the 

beds over the continuation of the Mendip Axis, in a region where exposures 

were particularly to be desired but had previously been few and meagre. 1 

In the southern cutting, immediately beneath a sandy clay forming the 

base of the Kellaways Beds, the brachiopods of the siddingtonensis zone, M. 

siddingtonensis and Rhynchonelloidea cerealis, abounded in about 2-3 in. of 

ferruginous rottenstone. In the northern cutting the bed had expanded to 

1 ft. of hard, purplish, doggery limestone. This was all that represented the 

Upper Cornbrash. The lagenalis zone was entirely absent. 

The bed beneath formed the principal feature of the Cornbrash, consisting 

of a solid block of very hard, grey to purplish, sandy limestone, 3 to 4 ft. thick, 

the upper portion deeply piped by solution cavities. Palaeontologically it was 

of great interest, for the lower part contained in abundance the fauna of the 

Astarte-Trigonia Bed, and the upper yielded numerous Perisphinctids of 

the ' Homoeoplanulites* (Choffatia) subbakerice type, associated with abundant 

Pseudomonotis echinata and an occasional specimen of Ornithella obovata. 

The lithology suggested Upper Cornbrash and similar Perisphinctids are common 

at Stalbridge in association with M. siddingtonensis and R. cerealis, but 

the brachiopod and the Pseudomonotis prove beyond doubt that at Frome 

this bed is part of the obovata zone. 

The upper part of this bed had been long exposed near by at Berkley, 

north-east of Frome, and at Wanstrow and Cards Farm, South Brewham, to 

the south-west. At Cards Farm it is seen in the road-cutting, occupying 

a position between the Astarte-Trigonia Bed and the lagenalis zone. On 

stratigraphical grounds it had, therefore, been assigned to the siddingtonensis 

zone, though the rare Ornithellids (or Microthyrids) found in it only at 

Berkley could not be identified with certainty. 

Beneath the Astarte-Trigonia Bed the railway-cutting showed normal marls 

with rubble and abundant Ornithella obovata (3-4 ft.), and at the base a hard 

band of limestone (1-2 ft.) with Cererithyris intermedia. The Lower Cornbrash 

is similarly developed at Hilperton, on the Trowbridge inlier (except 

for the presence of Corston Beds and the absence of the solid block of limestone 

of Frome), and again at Wincanton to the south. 

1 The following account is from my field-notes; a description is to be published by Dr. 

F. B. A. Welch, in the Sum. Prog. Geol. Surv.

CORNBRASH: MENDIPS AND WILTSHIRE 331 

At Chatley (a Sowerbyan type locality), Tellisford and Rode, a short distance 

north of Frome, shallow pits expose Lower Cornbrash, in which the 

faunas of the intermedia and obovata zones are mingled in a single bed of 

rubble. These exposures are somewhat to the north of the line of the Mendip 

Axis, and in view of the more regular development of the beds in the Frome 

cuttings, the admixture of faunas which they show can scarcely be attributed 

to the influence of the axis. 

III. THE DIP-SLOPE OF THE COTSWOLD HILLS 1 

In the Cotswold district, from the neighbourhood of Bath to the neighbourhood 

of Oxford, the Cornbrash marks the natural boundary between the hills 

and the Oxford Clay vale. The distribution of the several zones in this 

district, so well demarcated in Inferior Oolite times by the axes of uplift along 

the Mendips on the one hand and the Vale of Moreton on the other, admits 

of certain generalizations, but there are local anomalies which show that by 

this time the movements controlling deposition had grown more feeble and 

perhaps more complex. 

We have seen how in the Dorset-South Somerset area the dominant role 

is played by the Upper Cornbrash, which becomes thinner at South Brewham 

and Frome and disappears near Trowbridge. Conversely it may be said that 

in general in the Cotswold province, and from Frome as far north as Bedford, 

the Lower Cornbrash plays by far the most important part, while the Upper 

Division is recessive or absent. An exception must be made, however, of the 

central region from Malmesbury to Fairford; for here the Upper Cornbrash 

returns in force and the Lower is reduced to a rubble with mixed intermedia 

and obovata faunas, or to a condensed fossil-bed. 

(a) Trowbridge to Malmesbury 

From south of Trowbridge to Malmesbury the Upper Cornbrash is represented 

at most by a few feet and usually by only a few inches of brow r n marl, 

containing crushed specimens of Microthyris lagenalis, with occasional Rh. 

cerealis. The bulk of the Cornbrash is made up of the CORSTON BEDS {obovata 

zone), which consist of bands of massive limestone, originally dark-centred 

but weathering white, and forming an important surface feature about 

Chippenham, Clanville, Stanton St. Quintin and Corston. At the type 

locality of Corston the limestones have an apparent thickness, measured at 

right angles to the bedding, of 50 ft. or more, but they were evidently deposited 

with a deposition dip and their true thickness may be no more than 

25 ft. Fossils are usually limited to clusters of Pseudomonotis echinata, but at 

Corston and one or two other places there are considerable numbers of seaurchin 

tests (Pygurus michelini and Acrosalenia hemicidaroides) and a peculiar 

brachiopod, found in no other part of England, Ornithella foxleyensis Dougl. 

and Ark. 

Both at Chippenham and at Bancombe Wood, south of Rodbourn, the 

Corston Beds have an eroded upper surface to which oysters (Lopha marshii) 

are attached, and upon the surface rests the thin representative of the Upper 

Cornbrash, without the intervention of any Astarte-Trigonia Bed. 

On approaching Malmesbury, how r ever, as may be seen in the Foxley Road 

1 Based on Douglas and Arkell, 1928, loc. cit., pp. 127-42; and 1932, idem, part 2, Q.J.G.S 

vol. lxxxviii, pp. 123-7.


Quarry, the Corston Beds lose their characteristic identity, the Astarte- 

Trigonia Bed returns, and Ornithella foxleyensis is found below in ordinary 

obovata-zone rubble. The intermedia zone is nowhere seen in the vicinity of 

Malmesbury. 

To the north-east, at Garsdon and Charlton, the Corston Beds are still well 

developed, but a few miles farther in the same direction, at Shorncote, the 

whole of the Lower Cornbrash is reduced to a single condensed bed 2 ft. thick, 

crowded with fossils of both obovata and intermedia zones. In between these 

places, at Poole Keynes and Murcott, a glimpse is seen of the Astarte- 

Trigonia Bed resting upon Corston Beds. 

(b) Malmesbury to Fairford and Witney 

The chief interest from north of Malmesbury as far as Fairford centres in 

the Upper Cornbrash, which is about 

CORNBRASH 

6-8 ft. thick and contains M. siddingtonensis 

in the lower part and M. lagenalis 

in the upper. Certain bands of 

purplish sandy limestone, reminiscent of 

those in Dorset, also yield abundant 

Macrocephalites macrocephalus, Kamptocephalites 

herveyi and occasionally 

specimens of Choffatia. The brachiopods 

occur in dense clusters in perfect preservation 

in a soft marl, and a small quarry 

at Milton End, Fairford, was long renowned 

for its unique yield of M. 

lagenalis, M. sublagenalis, &c. in flawless 

condition. The excavation is now unfortunately 

filled up and grass has been 

sown over it. 

The base of the Upper Cornbrash at 

Charlton is a boulder-bed of rolled and 

bored lumps of limestone around which 

FIG. 59. Section of the Cornbrash at are loose shells of M. siddingtonensis 

u a n 

u 

(kElLAWAY5 

CLAy) 

LAGENALIS 

SIDDING- 

TONENSIS 

d 

R t- c r alis - S O M V F BOULDERS 

Q.J.G.S., vol. Ixxxiv, p. 138.) when broken open are round to contain 

Lower Cornbrash fossils, but others are 

composed of hard purplish limestone containing M. siddingtonensis. In a 

neighbouring quarry at Garsdon the hard siddingtonensis bed, from which 

some of the boulders seem to have been derived, is still present beneath the 

boulder bed and rests in turn upon another eroded surface at the top of the 

Corston Beds (fig. 59). There is thus clear evidence of erosion and removal 

of the Astarte-Trigonia Bed prior to or at the beginning of the deposition of 

the siddingtonensis zone and also the continuation or repetition of the erosion 

during the siddingtonensis hemera, with the breaking up and rolling of previously-solidified 

siddingtonensis beds. 

About Cirencester 1 and Fairford the Upper Cornbrash forms a considerable 

surface feature, consisting chiefly of purplish limestone of an almost 

1 Near here is the village of Siddington, which gave its name to the zonal brachiopod.

CORNBRASH: OXFORDSHIRE 333 

flinty hardness. Fossils are rare, but at Poulton the limestone yields Microthyris 

sublagenalis and M. siddingtonensis, while farther east, at Broughton 

Poggs, it is overlain by a marl containing dense clusters of the typical Microthyris 

siddingtonensis as at Fairford, together with Kamptocephalites herveyi. 

The latter, indicative of the Upper Cornbrash, has been found as far east as 

Witney. 

(c) Oxfordshire: Witney to Buckingham 

The outcrop from Witney eastward through Oxfordshire to Buckinghamshire 

resembles that between Trowbridge and Malmesbury in the absence or 

meagre representation of the 

Upper Cornbrash and the thick 

development of the Lower. 

The Upper Cornbrash is exposed 

at Long Handborough, 

in the Swan Inn Quarry, where 

it is only 1 ft. thick (fig. 60). 

Under the Kellaways Clay are 

marl and crushed M. lagenalis 

and ill-preserved small Macrocephalitids, 

resting upon a 6-in. 

band of hard purplish limestone 

with M. siddingtonensis, Rh. 

cerealis and other typical fossils, 

which reposes in turn upon 

the Astarte-Trigonia Bed. The 

Upper Division seems to be 

somewhat thicker towards the 

Cherwell Valley, for in the 

Shipton-on-Cherwell railwaycutting 

(now obscured) Woodward 

recorded 3 ft. 8 in. of 

beds containing M. lagenalis. 1 

On the opposite side of the 

valley, however, at Greenhill, 

UPPER 

CORN BRASH 

LOWER 

CORNBRASH 

(PLEISTOCENE 

GRAVEL) 

(KFLLAWAY5 CLAY) 

JRLR.-JR^LAGENALIS 

SIDDING- 

TONENSIS 

ASTARTE-TRIGONIA 

HORI10N 

OBOVATA 

INTERMEDIA 

(FOREST 

MARBLE) 

FIG. 60. Section of the Cornbrash at Long Handborough, 

Oxfordshire. (From J. A. Douglas and W. J. 

Arkell, 1928, loc. cit., p. 128.) 

Enslow Bridge, Upper Cornbrash is absent altogether, and it is again 

wanting in an exposure of the junction with the Kellaways Clay at Akeley 

Brickyard, north of Buckingham. 

The Lower Cornbrash, on the other hand, is well developed, usually from 

6 ft. to 10 ft. thick. It forms broad slopes of typical red stone-brash land, 

especially characteristic of the country between Oxford, Woodstock and 

Bicester, where it caps the plateau between the valleys of the Rivers 

Cherwell and Evenlode. Along these valleys are numerous sections, most of 

them incidental to the exploitation of the underlying Great Oolite, from which 

the Cornbrash has to be removed as overburden. Supplementary information 

is afforded by the line of inliers along the Islip Anticline, rising through the 

Oxford Clay lowlands of Otmoor, at Islip, Charlton-on-Otmoor, Ambrosden 

and Blackthorn Hill. 

1 H. B. Woodward, 1894, p. 447.


All these exposures show a rather monotonous alternation of rubble with 

rubbly or platy limestones, most of which belong to the obovata zone. O. 

obovata is abundant, together with Ps. echinata, Nucleolites clunicularis and 

casts of Pleuromya, Homomya, Pholadomya, Gresslya, &c. At certain levels 

Clydoniceras discus and allied forms are not uncommon, while the Astarte- 

Trigonia fauna is also frequently in evidence. Here and there, especially at 

Stratton Audley and other places near Bicester, some of the zone is a hard, 

poorly-fossiliferous flaggy limestone recalling the Corston Beds. 

At the base is normally a band of cream-coloured limestone crowded with 

Cererithyris intermedia. It is conspicuous as far west as Southrop, and at 

Brize Norton, Witney, Handborough, Kidlington, Charlton-on-Otmoor, and 

Akeley near Buckingham. It, too, occasionally yields Clydoniceras. Along the 

sides of the Cherwell Valley and in the Islip inlier, however, the bed is absent, 

and C. intermedia is found disseminated through the obovata zone at levels 

several feet higher, while the Astarte-Trigonia assemblage, usually characteristic 

of the top of the Lower Cornbrash, appears near the bottom. This admixture 

of faunas may result from penecontemporaneous erosion and redeposition, 

but it is more likely to have an ecological explanation. In view 

of the long range of allied Terebratulids in the Great Oolite, it is unreasonable 

to assume that C. intermedia became extinct after attaining its acme at the 

beginning of the Lower Cornbrash; it is more probable that the unfavourable 

conditions which terminated its acme and caused it to be succeeded by 

Ornithella obovata drove off straggling survivors to other parts of the sea-bed, 

not previously colonized. Once again we must be careful to distinguish the 

epibole from the biozone. 

IV. BEDFORDSHIRE AND DISTRICT 1 

Near Buckingham the outcrop of the Cornbrash enters a Drift-covered 

area, in which exposures are few and poor. Besides the mantle of Drift, an 

additional reason for the failure of exposures is the thinning of the Cornbrash 

and the thickening of the argillaceous strata beneath it, so that it becomes 

a thin rock-band between two clays. In the past the Kellaways Clay was 

worked in several small brickyards, which penetrated to the underlying rock, 

but with modern centralization nearly all have been abandoned. One such 

brickyard was situated north of the Ouse at Felmersham, and from it and from 

Great Oolite quarries south of the river, a former rector, the Rev. T. O. 

Marsh, sent a number of fossils to Sowerby to be figured in the Mineral 

Conchology. One was named Ostrea marshii after its donor, who is thus 

commemorated in one of the most conspicuous and abundant fossils of the 

Upper Cornbrash. 

The old brickyards along the Ouse Valley at Bedford, at Bourne End, 

Bletsoe, and West End, Stevington, were visited and described by H. B. 

Woodward before they fell into ruin. From his descriptions it is evident that, 

although the total thickness is no more than 2-3 ft., fossils of both Upper and 

Lower Cornbrash are present. The 'band of tough shelly limestone' was 

described as yielding O. obovata and Clydoniceras as well as M. lagenalis, 

Ostrea (Lopha) marshii and Macrocephalites. 2 

1 Based on Douglas and Arkell, 1932, loc. cit., pp. 127-9. 

2 H. B. Woodward, 1894,JR

CORNBRASH: NORTHAMPTONSHIRE 335 

Judging by the narrowness of the outcrop along the banks of the Ouse 

Valley and in the outer escarpment between Bozeat and Rushden, the Cornbrash 

seems to be thinly developed over the whole of the area where Dr. 

Rastall has shown the continuation of the Charnwood Axis to lie. 

On the prolongation of the Nuneaton Axis at Stowe Nine Churches, 8 miles 

west of Northampton and some 13 miles from the main outcrop, is a small 

outlier of Cornbrash owing its preservation to faulting. Here the thickness is 

again only 3 ft. All of it is Lower Cornbrash, for Clydoniceras occurs at the 

top. 

In connexion with the changes in thickness of the different parts of the 

formation in the Midland Counties it should be noted that the boring at 

Calvert, 6 miles south of Buckingham, seemed to show that the Cornbrash 

and Kellaways Beds were absent altogether, although the site of the boring 

is only 3 miles from the nearest inlier at Marsh Gibbon and barely a mile 

farther from the main outcrop. 

V. NORTHAMPTONSHIRE AND LINCOLNSHIRE TO THE HUMBER 1 

Along the 90 miles of outcrop from Higham Ferrers in the Nene Valley to 

the Humber, the Upper Cornbrash is paramount once more and is continuously 

developed, while the Lower Division is seldom seen and makes 

little of a surface feature. 

West of Peterborough, although the Cornbrash is much dissected, the total 

area covered by it (largely as inliers and outliers) is considerable. Farther 

north the outcrop soon narrows, and for the last thirty miles, along the 

eastern foot of the slope leading up to Lincoln Edge, it is a mere strip. 

The best sections are situated in the vicinity of Thrapston, Northants, 

where the Great Oolite beneath is exploited as a flux in the iron furnaces, but 

about Peterborough and in South Lincolnshire the Upper Cornbrash has 

been quarried extensively as a road stone and wall stone. A quarry at Thrapston 

was visited by William Smith, who noticed that the rock shown was 

Upper Cornbrash, because it contained O. marshii. 2 

At the top is generally a thin representative of the lagenalis zone, best seen 

at Thrapston L.M.S. Railway Station Quarry, where it is 1 ft. 8 in. thick 

and richly fossiliferous. It consists of ferruginous marls and impersistent 

rusty limestone, crowded with very perfect specimens of the zonal brachiopod, 

together with large oysters, Ostrea undosa and Lopha marshii, the former often 

bearing the imprint of other bivalves upon which they grew, especially 

Trigonia scarburgensis Lyc., Gervillia sp. and Chlamys (Radulopecteri) 

anisopleurus (Buv.). The bed also yields vertebrae of Murcenosaurus, and has 

furnished a wealth of Polyzoa, which have formed the subject of a special 

memoir by G. R. Vine. 3 

The principal feature of the Cornbrash in the Peterborough district and 

northward through Lincolnshire lies immediately below the lagenalis zone. 

It is a solid band of tough, grey limestone, weathering flaggy and creamcoloured. 

At first sight it recalls the solid block of limestone of Berkley and 

Frome, but it yields a different fauna, which ranges it with the hard purplish 

1 Based on Douglas and Arkell, 1932, loc. cit., pp. 129-37. 

2 In Phillips's Memoirs of William Smith, 1844, p. 75. 

3 G. R. Vine, 1892, Proc. Yorks. Geol. Soc., N.S., vol. xii, pp. 247-58.


flaggy limestone of Poulton. At Thrapston and in numerous other exposures 

farther north search reveals Microthyris sublagenalis, M. siddingtonensis var., 

Lopha marshii and other definitely Upper Cornbrash fossils. Although the 

typical M. siddingtonensis, such as occurs in clusters in Gloucestershire and 

elsewhere, has never been found north of Oxford, this bed is taken to represent 

the siddingtonensis zone. 

At the base of the zone at Thrapston is a pebble-bed like that at Charlton 

and Garsdon near Malmesbury. The pebbles consist of hard purple-centred 

Cornbrash, well bored by Lithophaga and encrusted with Serpulce, but unlike 

those at Charlton they have yielded no contemporary fauna. Associated with 

them are numerous small Macrocephalitid ammonites, especially Dolicephalites 

typicus and Kamptocephalites hudlestoni. This bed rests directly on 

the Lower Cornbrash, a single band of grey and white chalky and rubbly 

limestone, only 5 in. thick, packed with fossils, and closely resembling, both 

lithologically and palaeontologically, the development at Shorncote near 

Cirencester. It yields both Cererithyris intermedia and O. obovata, with 

Clydoniceras. 

The pebble-bed is only a local feature, for at Islip Ironworks, near Twywell, 

it has disappeared, and the Lower Cornbrash has thickened to about 2 ft. To 

the north, at Barnwell, near Oundle, the Lower Division is exceptionally 

developed, reaching nearly 5 ft.; but such a thickness is purely local. 

The faulted inlier between the villages of Stilton and Yaxley, south of 

Peterborough, formerly yielded numerous fossils characteristic of both 

Upper and Lower Cornbrash, but the only exposure has been completely 

obscured for at least thirty years. Here the types of Kallirhynchia yaxleyensis 

(Dav.) and Ornithella stiltonensis. (Dav.) were obtained. The exact horizon 

of the latter has not yet been determined. Numerous Macrocephalitid 

ammonites have been collected about Peterborough, especially at Castor, 

Chesterton and Stanwick, and may be seen in the Peterborough and other 

museums. 

About Bourn and Sleaford, all the exposures show the siddingtonensis zone, 

which is generally divisible into three distinct elements. At the top is the 

hard, purplish-grey limestone with M. sublagenalis and M. siddingtonensis 

var., as about Peterborough, w T hich forms the principal surface feature; in 

the middle is a yellow sandy marl, crowded with perfect specimens of Lopha 

marshii and Ostrea undosa and other fossils; while at the base is a solid block 

of tough, grey-centred, poorly fossiliferous limestone. Such tripartite sections 

are to be seen at Hacconby, Handthorpe and other places in the vicinity of 

Bourn, and at Quarrington and Roxholm near Sleaford. The yellow sandy 

marl is the home of a rare brachiopod, Tegulithyris bentleyi (Dav.), which is 

restricted to this part of England. 1 

In North Lincolnshire exposures are few and far between. The best is at 

Sudbrooke Park, north-east of Lincoln, where the whole Cornbrash can be 

seen, the Upper Division 3 ft. 6 in. thick, the Lower Division 1 ft. thick. 

Microthyris lagenalis has not been found here, but it was recorded from old 

workings no longer open, at Appleby. The chief element at Sudbrooke is still 

a purplish flaggy limestone, yielding the typical Upper Cornbrash fauna— 

Kamptocephalites herveyi, Trigonia scarburgensis, T. cassiopey Lopha marshiiy 

1 The type-specimen came from Handthorpe.

CORNBRASH: YORKSHIRE BASIN 337 

&c. The thin representative of the Lower Cornbrash is quite distinct, a hard, 

blue-hearted shelly band with Ornithella obovata, C. intermedia, Kallirhynchia 

yaxleyensis, Trigonia rolandi, Clydoniceras legayi and many other fossils. 

VI. THE MARKET WEIGHTON AXIS 

Where last seen south of the Humber, at Appleby, the Cornbrash is only 

3 ft. thick, and under the estuary it thins out altogether. In the oolite tract 

south of Market Weighton there is no sign of the rock or of the fossils associated 

with it, and it has been sought in vain all along the Howardian Hills and 

the southern part of the Hambletons. The first traces have been recognized 

at Kepwick, about 50 miles from the last vestiges south of the Humber. 1 


From Kepwick round the north end of the Hambleton Hills a thin sandy 

limestone has been followed inferentially at the base of the Kellaways Rock, 

but no exposures have indicated its nature or its thickness. At Shaken Bridge 

on the Rye some ironstone is believed to have been formerly obtained from 

the Cornbrash. The first definite indications, however, begin to be visible 

east of Bilsdale. From Bilsdale the rock strikes due east across the moors, 

thickening steadily towards Newton Dale, where it attains its maximum of 

about 5 ft., and it so continues to the coast at Scarborough. 2 

The steep sides of the glacial gorge of Newton Dale and its tributaries 

provide the best sections in Yorkshire, and are the finest natural sections of 

the Cornbrash in England. The rock consists of black, shelly limestone, 

sometimes oolitic, overlying an intensely hard, shelly, mottled purple and 

red band. Both parts contain in abundance the typical lamellibranchs of the 

Upper Cornbrash found south of the Humber, such as Lopha marshii, Ostrea 

undosay Trigonia scarburgensisy T. cassiope, Chla?nys (Radulopecten) anisoplenrus, 

&c., but the brachiopods are unfamiliar and ammonites extremely 

rare; the principal brachiopod is Burmirhynchia fusca Doug, and Ark. 

The 5 ft. of Cornbrash immediately overlies about 7 ft. of blackish sandstone, 

the two together forming a conspicuous hard band, which stands out 

of the shale as a prominent feature along the cliffs. The sandstone was included 

in the Cornbrash by Fox-Strangways, but although it may represent 

an estuarine development of the Lower Cornbrash, it does not appear to yield 

any fossils other than traces of possibly Serpulce. Until diagnostic species 

have been found, it should be grouped with the Upper Estuarine Series. 

Towards the coast the thickness is maintained. The best section in East 

Yorkshire is the large quarry, formerly known as Peacock's Quarry, in the 

side of the hill near Scarborough Railway Station. The Cornbrash is still a 

solid block with the same fauna as inland, but the upper part is red and the 

lower part dark blue-grey. The same arrangement holds in the coast sections 

between Scarborough and Filey, and everywhere a thin marly layer at the top 

abounds in crushed specimens of M. lagenalis. This passes down imperceptibly 

into the limestone, of which it may be the decalcified top layer. Above are the 

grey shales belonging to the Kellaways Beds, but formerly called the 'Shales 

of the Cornbrash\ 3 

1 H. C. Versey, 1928, Naturalist, p. 117. 2 C. Fox-Strangways, 1892,J.R.B.} pp. 270-2. 

3 J. A. Douglas and W. J. Arkell, 1932, loc. cit., pp. 137-41.


The best natural section on the coast at present is in Cayton Bay, where the 

rock outcrops through the sand for a distance of several hundred yards along 

the beach below Red Cliff. Most of the protruding fossils have long been 

removed, but a century ago local collectors, chief among whom was Bean, 

obtained rich harvests here. The other source from which the large collections 

now in Scarborough, York, the Sedgwick and other museums were made 

was the beach below Scarborough Castle. Blocks of fossiliferous limestone 

strewed the foreshore before the building of the undercliff road, but as they 

w r ere derived not only from the Cornbrash, but also from various parts of the 

Kellaways and Hackness Rocks, and the Corallian, a number of mistakes in the 

location of the various species were inevitably made. 

Between Scarborough and Cayton Bay the Cornbrash appears for a short 

distance at the top of the cliff at Wheatcroft, and to the south it dips down 

below sea-level in Gristhorpe Bay, where it is, however, much obscured by 

landslips. From Scarborough southward there is a steady diminution in 

thickness, from 5 ft. to 18 in., the conclusion being that a few miles farther 

south, towards the Market Weighton Axis, the Cornbrash thins out altogether 

as in the western escarpment. 

The zonal position of the Yorkshire Cornbrash is difficult to determine for 

the same reasons as are various parts of the Kellaways Beds and Oxford Clay, 

namely, that many of its fossils are not found south of the Market Weighton 

Axis. The lamellibranch fauna is, with few exceptions, the same as that in 

the Upper Cornbrash of Lincolnshire, and most of the principal species occur 

in the Llpper Cornbrash all over England. The brachiopods, however, are 

more restricted in their distribution. The presence of Microthyris lagenalis 

indicates the highest zone, and it seems to occur only at the top of the rock 

as in other parts of England. On the other hand, there is no M. siddingtonensis 

or M. sublagenalis, or any of the familiar Rhynchonellids, while the Macrocephalitid 

ammonites for the greater part belong to different species from 

those in the Upper Cornbrash in other counties. Neither Clydoniceras nor 

Cererithyris have been obtained, but there are in the York collection a few 

specimens of Ornithella obovata. If the label proclaiming these to have come 

from Yorkshire is to be relied upon, the whole of the deposit may not 

belong everywhere to the Upper Division, as would seem to be the conclusion 

from the field evidence. 


Only one small patch of Cornbrash is known in Scotland, in the central 

upland of Raasay. 

'This was discovered during the recent survey 9/10 mile NE. of Storav's grave, 

on the right bank of the middle branch of the Glam Burn, 300 ft. west of the basalt 

boundary. The ground is exceedingly difficult of interpretation owing to faulting, 

-drift and peaty covering, which makes it impossible to estimate the extent of the 

Cornbrash area, though there is no doubt that the beds referred to it follow upon 

the Great Estuarine Series. 

'What is seen of the sequence consists of 15 feet of gritty white limestone, strikingly 

granular and unlike any other rock in Raasay, with comminuted fossils, resting 

on some 6 or 8 feet of gritty, flaggy limestone, darker and with red ironstone nodules. 

This lower limestone is full of comminuted fossils, but has also yielded a few that 

are entire and sufficiently determinable to give a clue to its age. Most of the fossils

CORNBRASH: SCOTLAND AND KENT 339 

obtained are brachiopods, which were submitted to Mr. fiuckman, who determined 

them as follows: Ornithellay two species, Rhynchonella, three or four species, Terebratula 

intermedia Sow.' 1 

Lithologically the fossiliferous limestone bears a striking resemblance to 

some of the flaggy forms of Lower Cornbrash of the obovata zone in Southern 

England. Its presence provides an interesting additional link between the 

Hebridean area of deposition and that of South and Central England, and 

a further contrast with the Yorkshire Basin in Jurassic times. 

In Skye and Eigg either Kellaways Beds (koenigi zone) or some part of the 

Oxford Clay everywhere rest directly upon the Great Estuarine Series, without 

the intervention of any Cornbrash. 


If there is any deposit of the age of the Cornbrash in Eastern Scotland it is 

of 'estuarine' origin and indistinguishable from the Estuarine Series below. 

The first horizon above the Estuarine Series with marine fossils is the Brora 

Roof Bed, of the age of the Kellaways Clay (koenigi zone). 

X. KENT 2 

Most of the typical fossils of both Upper and Lower Cornbrash were 

obtained in the borings in Kent, but there are insufficient data on which to 

base any conclusions as to the development of the various zones. The cores 

showed varying alternations of marls and limestone bands, the basal limestone 

being usually the most fossiliferous and having often a pisolitic structure. 

C. intermedia, O. obovata, M. cf. siddingtonensis and M. lagenalis were recorded, 

as also Macrocephalitid ammonites and a large number of lamellibranchs, 

but no succession of faunas has been made out. At Guildford the 

total thickness is about 10 ft., but at Tilmanstone it is much greater, totalling 

24 ft., or about the same as in the area of maximum thickness at the outcrop, 

on the Dorset coast. Here 7 ft. of nodular and pisolitic limestones are overlain 

by 17 ft. of hard grey limestone with Macrocephalites, suggesting some of the 

Upper Cornbrash limestones of Dorset and Gloucestershire. According to 

the records, M. lagenalis occurred at Tilmanstone to within 1 ft. of the base, 

mixed with O. obovata and C. intermedia, and rearrangement is suggested by 

'numerous flat nodules of irregular shape, some of which exceed two inches 

in length'. 3 

The Cornbrash was found to be overlain in nearly all the Kent borings by 

a sandy clay with a Pseudomonotis (less inflated and less strongly ribbed than 

P. echinata), which was correlated with the shales overlying the rock in Yorkshire 

and other parts of England. In the official records this shale was included 

in the Cornbrash, but as has already been stated, it is better grouped 

with the Kellaways Clay. 

1 G. W. Lee, 1920, 'Mesozoic Rocks of Applecross, Raasay, &C.', Mem. Geol. Survp. 58. 

2 Based on Lamplugh and Kitchin, 1922, loc. cit., and Lamplugh, Kitchin and Pringle, 

1923, loc. cit. 

3 Lamplugh, Kitchin and Pringle, 1923, loc. cit., p. 142. Could the brachiopods at the base 

recorded as M. lagenalis have been Ornithella classis ? This species might be expected in Kent, 

where the total thickness and lithology of the Cornbrash are much the same as on the Dorset 

coast.

TABLE SHOWING THE ZONES INTO WHICH THE OXFORD CLAY AND KELLAWAYS BEDS 

HAVE BEEN DIVIDED BY DIFFERENT AUTHORS 

Buckman Morley Morley 

1913 and Davies Neaverson Spath Davies Brinkmann Pringle Adopted 

Ages. I9I5- 1916. 1925. 1926. 1929. 1929. 1930. Here. 

scarburgense 

base of 

CARDIOCERATAN 

(Icordatum 

vernoni prcecordatum precordatus 

(with vernoni 

prcecordatum scarburgense prcecordatum 

( - scarburzone 

s.l.) 

and renggeri) 

gense auct.) 

gregarium 

tenuicostatum 

QUENSTEDTOCERATAN 

(= Vertumniceratan) 

(lamberti 

zone s.l.) 

vertumnus 

renggeri 

lamberti 

renggeri 

lamberti 

marice (with ver- vertumnus 

tumnus and renggeri) 

renggeri 

lamberti 

(with lalandei 

and bicostata) 

lamberti 

marice 

renggeri 

lamberti 

renggeri 

lamberti 

pronice 

athleta athleta athleta athleta 

athleta athleta 

spinosum 

(with pronice 

(=-•- ornatum 

and spinosum) 

auct.) 

duncani duncani duncani 

(with athleta 

and pronice) 

duncani 

duncani duncani 

ornatum 

reginaldi castor reginaldi castor reginaldi 

KOSMOCERATAN (with castor (with corona- 

(ornatum or 

athleta zone s.l.) 

< 

coronatum 

and pollux) 

coronatum coronatum 

fraasi (with 

castor and 

pollux (with 

coronatum 

tum, castor 

and pollux) 

elizabethce elizabethce castor and stutchburii coronatum) elizabethce 

or jason pollux and 

coronatum) 

anceps 

conlaxatum jason jason (-- con- con- 

(with jason) 

(= conlax- conlaxatum laxatum, with 

atum) 

elizabethce, &c.) 

R calloviense anceps (with callo- calloviense 

calloviense calloviense 

REINECKEIAN 

(anceps zone s.l.) 

1 

I 

koenigi 

viense and gulielmi) 

rehmanni 

(with konigi) 

koenigi koenigi koenigi

CHAPTER XII 

OXFORD CLAY AND KELLAWAYS BEDS 

Zones Strata. 

(Plates XXXVI-VII). Dorset-Humber. Yorks. 

Cardioceras prcecordatum 1 Basal Lower Calc. Grit. 

Creniceras renggeri 2 Clays with OXFORD C L A Y ^ - — 

Quenstedtoceras lamberti3 >« 

3 

ammonites 

chiefly as 

Peltoceras athleta 0 pyritic casts. 

0 

Kosmoceras duncani | i tf 

Erymnoceras reginaldi 4 ; 

Kosmoceras jason 5 

Q Shaly clay 

with compressedKosmocerates 

Sigaloceras calloviense ! KELLAWAYS ROCK ? 

Proplamdites koenigi \ 

I 

KELLAWAYS CLAY 

C/5 

W 

£ 

u 

< 

MH 

KELLAWAYS ROCK 

& SHALES 50 ft. + 

I. DORSET TO THE MARKET WEIGHTON AXIS 

u 

3 

tf 

OS 


THE Oxford Clay, like the other Jurassic rocks outcropping at Weymouth, 

covers a small area completely separated from the main outcrop to the 

north by the overstepping Chalk of the Downs. The low ground floored by 

the soft Oxford Clay has been hollowed out from the east to form Weymouth 

Bay, behind which lie the Lodmoor Marshes and the Radipole Backwater. 

1 This species was described by R. Douville, first as a Cardioceras, then as a Quenstedtoceras; 

but, although its characters are said to be to some extent intermediate, Douville's figures 

show it to be a typical cordate Cardioceras; indeed, he said that it passed by insensible gradation 

into Cardioceras cordatum (1912, Mem. Soc. geol. France, vol. xix, p. 62, pi. IV, figs. 10-20); 

see also Morley Davies, Geol. Mag., 1916, p. 397, and Buckman, T.A., vol. v, 1924, p. 32. 

As a zonal index it replaces 'scarburgense' auctt., the true scarburgense having proved to be 

something different (Buckman, T.A., vol. v, 1924, p. 32). The zone was originally called the 

Pre-cordatus zone by Buckman (1913, Q.J.G.S., vol. lxix, p. 159). 

2 Between the renggeri and prcecordatum zones Buckman placed three zones, vertumnus, 

gregarium and vernoni, found only in Yorkshire. It is not fully known to what extent any or all 

of these are contemporary with the faunas south of the Humber, but the vernoni zone may 

safely be regarded as synonymous with the prcecordatum zone and probably the other two with 

the renggeri. 

3 Made genotype of Bourkelamberticeras Buckman, 1920, T.A., vol. iii, p. 17. (Synonym.) 

4 Introduced by Morley Davies, Geol. Mag., 1916, and retained by him in the Handbook of 

the Geology of Great Britain, 1929. It is equivalent to Buckman's zone of Erymnoceras coronatum, 

which corresponds according to Brinkmann with the maximum of Kosmoceras castor 

and K. pollux. 

5 According to Brinkmann (1929), Kosmoceras conlaxatum Buckman, which was used as 

index of the basal zone of the Oxford Clay by Neaverson, is a synonym of K. jason Reinecke, 

which therefore takes priority. The zone as used here includes the elizabethce zone of Morley 

Davies (1916) and Neaverson (1925), K. elizabethce (Pratt) being according to Brinkmann 

(1929) synonymous with K. ornatum (Schloth.) non auctt. Morley Davies (1929) chose 

Kosmoceras stutchburii (Pratt) as index, but according to Brinkmann that species is a synonym 

of K. gulielmii (Sowerby). Note: the lamberti to prcecordatum zones comprise Oppel's zone 

of Am. biarmatus. 

CA 

£ 

O

FIG. 6I. Sketch-map of Weymouth and Portland.

OXFORD CLAY: DORSET COAST 343 

The clay underlies the bay from Redcliff and Jordan Hill in the north to the 

entrance to the harbour in the south, and in both directions it dips below sealevel 

under the Corallian Beds. Thus the lowest zones rise to the surface in 

the centre of the bay, where there are no exposures, only an esplanade 

separating the sea from the town and the marshes. 

Only at the north end of the bay, under Jordan Hill (between Overcombe 

and Bowleaze) and on the east side of Redcliff Point (Ham Cliff) are there any 

natural cliff-sections; here the upper half of the clay is exposed, from the 

junction with the Corallian down to the lamberti zone. These zones occupy 

about half the total thickness of the Oxford Clay and Kellaways Beds, which 

has been estimated to reach about 500 ft. The old exposure at the south end 

of the bay has been obliterated by the fortification of the Nothe. 

The base of the Lower Calcareous Grit, and so of the Corallian formation, 

falls in the midst of the Cardioceratan deposits. The grits become bluish-grey 

and argillaceous downwards, but there is nevertheless a sharp lithic change 

to the grey, soapy Oxford Clay below. Immediately beneath the grit at Ham 

Cliff and Jordan Cliff, and faulted up to sea-level at the end of Redcliff Point, 

are the RED NODULE BEDS. 1 These clays contain, as their name implies, lines 

of red claystone nodules, which occasionally enclose fossils: the types of 

Modiola bipartita Sowerby and Thracia depressa (Sow.) were obtained from 

them over a century ago. The beds are most conspicuous, however, by reason 

of the large quantities of Gryphcea dilatata which they contain, often of great 

size. 

Below the Red Nodule Beds, and forming the greater part of Jordan Cliff, 

are thick clays which Buckman named the JORDAN CI IFF CLAYS. These are 

also full of large specimens of Gryphcea dilatata, of which they are, indeed, 

the chief repository. They yield in addition a fauna of small Cardiocerates, 

denoting the lower part of the prcecordatum zone, and the large Peltoceratoides 

hoplophorus (S. Buck.). 2 The Red Nodule Beds are presumed to be the upper 

part of the same zone. 

The lowest clays of all exposed on the coast north of Weymouth are seen 

for a short distance beneath the fault east of Redcliff Point. They belong to 

the lamberti zone (see fig. 65, p. 382). 

Lower zones, down to the Kellaways and Cornbrash, are to be seen sporadically 

in small banks around the north shore of Radipole Backwater, but it is 

difficult to make out the sequence. 

Westward the Weymouth Anticline brings Cornbrash, Forest Marble and 

Fuller's Earth to the surface, dividing the Oxford Clay into two strips, dipping 

away north and south. The northern strip is narrow and strikes the West 

Fleet backwater at Abbotsbury Swannery, where the shore is shelving and 

affords no exposure. The southern strip is shorter and twice as broad, but 

the coast-sections along the East Fleet are poor and discontinuous owing to 

the protective action of the Chesil Beach; while the harder rocks often form 

low cliffs, the clays tend to melt down in grassy banks. There are a number 

of small exposures, however, the best of which is at Tidmoor Point, behind 

1 Called by Buckman the Red Beds, an inappropriate name, preoccupied by Damon for 

Corallian deposits higher in the same cliffs. 

2 T.A., 1925, pi. DLXIV, and 1927, pi. DCCIII (named ' Peltomorphites', a synonym of Peltoceratoides 

according to Spath, 1931, Pal. Irtdica, N.S., vol. ix, p. 558).

MIDDLE OOLITES 

344 

the rifle-range. Here the clays of the lamberti zone crop out in a low, slipped 

cliff, and yield pyritic Quenstedtocerates. 1 There is also a band of small 

Oxytoma, belemnites, &c. Buckman distinguished the clays here as the 

TID(E)MOOR POINT BEDS, and correlated them with the lowest clays seen east 

of Redcliff Point. 2 

The lower zones are ill-exposed on the shore and the Kellaways Beds are 

probably carried below sea-level by a fault at East Fleet village. Two large 

brickyards less than a mile inland, south of Chickerell, however, display 

magnificent sections of several zones. The more westerly brickyard, half a 

mile due south of Chickerell Church, shows a 60 ft. face of shaly clays with 

crushed Kosmocerates and small bivalves (Nucula, &c.), principally belonging 

to the duncani zone. At many levels there occur sporadically large flattened 

spheroidal septaria, some of which contain badly preserved ammonites 

suggestive of Erymnoceras reginaldi. One dogger of intensely hard stone found 

somewhere low down in the pit, of much harder, more splintery matrix than 

the rest, was crowded with Erymnoceras coronatum in good preservation 

(reginaldi zone). 

The more easterly brickyard (that of the Dorset Brick, Stone and Ball Clay 

Co.), at a lower level, shows one of the best sections of the Kellaways Beds in 

the South of England. At the top of the pit is the Kellaways Rock—sand and 

yellow sandy clay with doggers and lenticles of hard sandstone, crowded with 

Gryphcea bilobata Sow. Below are dug some 10 ft. of blue Kellaways Clay 

full of Proplanulites spp., Cadoceras sublceve (Sow.) and Cadoceras tolype 

Buck. There are also numerous small round nodules, some of which are 

crowded with beautifully preserved shells of an Oxytoma. 

Small faulted tracts of Oxford Clay occur a short distance inland almost as 

far west as Bridport and from a faulted patch beneath the Fleet many fossils 

weather out and are cast up on the beach west of Langton Herring. 3 At 

Compton Valence, in the midst of the downs, a diminutive inlier has been 

brought to light by the erosion of a valley in the Chalk. 

(b) North Dorset and Wiltshire: the Vale of Blackmoor to the 

Vale of the White Horse 

From its emergence on the north side of the Dorset Downs the Oxford 

Clay forms all along its outcrop a continuous low-lying vale, most of which 

was until a few centuries ago thickly forested. The Blackmoor Vale in the 

south merges northward into the timbered vales of Pensehvood and later of 

Braydon Forest, which leads on to the Vale of the White Horse, forming the 

valley of the Upper Thames as far as Oxford. Braydon Forest, lying between 

Malmesbury, Cricklade and Chippenham, was not cleared until the reign of 

Charles I, and both there and in Penselwood extensive areas of woodland still 

remain. 

Throughout this tract the Oxford Clay and Kellaways Beds vary little in 

thickness, totalling from 550 to 600 ft., or a little more than on the Dorset 

coast. The estimated thickness in the south is 560 ft., while the Westbury 

boring proved 600 ft., and the Swindon boring 573 ft. 

1 Specimens are figured in T.A., 1920, pi. CLIV; 1922, pi. cccxxxix; 1925, pi. CLIVA. 

2 S. S. Buckman, T.A., 1923, vol. iv, p. 41; and 1925, vol. v, p. 66. 

* W. J. Arkell, 1932, Geol. Mag., vol. lxix, pp. 44-5.

OXFORD CLAY: WILTSHIRE 345 

Exposures are nowadays neither numerous nor very instructive, being 

limited to a few scattered brickyards. In the past, however, more or less 

complete sections have been furnished by railway-cuttings, long since grassed 

over. Three of these were fully described, and two became famous for the 

abundance of perfectly preserved ammonites and belemnites which they 

yielded. The main G.W.R. line from Swindon to Bath, built in 1840-1, 

passed over Oxford Clay for 10 miles between Wootton Bassett and Chippenham. 

For most of this distance the line was raised on an embankment and to 

obtain materials long pits were dug beside the railway. The pits are now 

lakes filled with rushes and water-lilies, but during their excavation they 

yielded many hundreds of fossils to local collectors. 

The richest harvest of all was reaped in a cutting near Christian Malford, 

4 miles from Chippenham, where the lower shales of the Oxford Clay (jasonduncani 

zones) were laid bare. S. P. Pratt 1 described some of the ammonites 

from here, and scores of specimens, flattened but otherwise perfectly preserved, 

have found their way into museums all over the country. Most of 

Pratt's types have recently been figured by Buckman in the last parts of 

Type Ammonites. They include the familiar species Kosmoceras elizabethce, 

K. stutchburiiy and K. sedgwicki, all of which Brinkmann has recently declared 

to be nothing more than varieties of other forms previously named 

(K. ornatum Schloth., K. gulielmii Sow. and K. jason Reinecke). The belemnites, 

Cylindroteuthis puzosi (d'Orb.) [=5. owenii auct.] and Belemnopsis 

hastatus (Blainv.) were sometimes found with their ink-sacs preserved. 

The second cuttings were made on the Weymouth branch of the G.W.R. 

at Trowbridge, and were described by R. N. Mantell and the fossils by G. A. 

Mantell and John Morris in 1848-50. 2 From here Morris figured the type 

of Erymnoceras reginaldi (named after Reginald Mantell). Although the 

deepest cuttings average only 14 ft. in depth, they exposed about 45 ft. of the 

Lower Oxford Clay, up to at least the reginaldi and probably the duncani zone, 

as well as the Kellaways Beds. From the latter large quantities of Sigaloceras 

calloviense and Proplanulites koenigi were obtained, while in the overlying 

shales the crushed ammonites and belemnites were as abundant as at Christian 

Malford, and much lignite was found. 

The most recent cuttings were made in 1898, during the construction of 

the G.W.R.'s South-Wales-Direct line, which crossed Oxford Clay for 

9 miles west of Wootton Bassett. For most of this distance the line was raised 

on an embankment, but this time no pits were dug as abundant material was 

available from the cuttings and tunnel which were being driven through the 

Forest Marble and Great Oolite farther west. Several cuttings were, however, 

made in the Oxford Clay and were described by H. B. Woodward, and again 

four years later by Messrs. Reynolds and Vaughan. 3 

Immediately west of Wootton Bassett Railway Station, under the bridge, the 

highest 9! ft. of the Oxford Clay was seen below the Corallian, but the only 

fossil found was a Thracia. This clay may be a lateral replacement of what is 

1 S. P. Pratt, 1841, Ann. Mag. Nat. Hist., N.S., vol. viii, pp. 161-5. The best account of 

the cuttings and their fossils is by Oppel, in Die Jurafor motion, pp. 535-6. 

2 R. N. Mantell and J. Morris, 1850, Q.J.G.S., vol. vi, pp. 310-19; G. A. Mantell, 1848, 

Phil. Trans. Roy. Soc., vol. cxxxviii B, pp. 171-83. 

3 H. B. Woodward, 1899, Sum. Prog. Geol. Surv. for 1898, pp. 188-92; S. H. Reynolds and 

A. Vaughan, 1902, loc. cit.

346 MIDDLE OOLITES 

elsewhere Lower Calcareous Grit sands. Ammonites indicating the Cardioceratan 

zones, and also Quenstedtoceras lamberti, were found in a cutting near 

Brinkworth, while farther west, miles east of Somerford Railway Station, 

another cutting showed the shaly Lower Oxford Clay, with Kosmoceras jason 

and other species of the zone. A brick pit at Rodbourne near by still displays 

the reginaldi zone, with crackers from which large specimens of the index 

fossil, measuring over i ft. in diameter, may be obtained. Another brickpit 

at Purton is also still worked, but there the clay is singularly barren. Prof. 

Morley Davies tells me that prolonged search resulted in his finding one 

ammonite, identified by Buckman as Cardioceras dieneriy l and denoting the 

prcecordatum zone. 

The best cutting on this line w T as that at the west end of the outcrop, passing 

through Bancombe (or Bincombe) Wood, between Rodbourne and Kingway 

Barn, near Corston. This laid bare the whole of the Kellaways Beds. The 

Kellaways Rock was represented by 10-20 ft. of poorly fossiliferous sandy and 

loamy beds, overlying 20 ft. of Kellaways Clay with septaria. From the 

latter abundant Proplanulites koenigi were obtained, with Gowericeras gozverianum 

(also denoting the koenigi zone). 

The thickest development of the Kellaways Rock exposed in the West of 

England was seen in a short cutting on the Midland and South-Western 

Junction Railway at South Cerney, near Cirencester, described by Harker. 

Here 22 ft. of yellow sands and ferruginous brown sands with nodules and 

large doggers were passed through. Fossils were again almost entirely absent. 2 

In other places where temporary openings have been made in the Kellaways 

Rock it has sometimes proved highly fossiliferous, although it is frequently 

much thinner—a variability remarked on by William Smith. An altogether 

peculiar development was described by Richardson 3 at Calcutt, near Cricklade, 

where a well proved above the Cornbrash 18 ft. of Kellaways Clay, 

followed by 18 ft. of Kellaways Rock (very hard calcareous sandstone), overlain 

in turn by 13 ft. of clay and then 25 ft. of fine-grained grey sand. If all 

these are rightly included in the Kellaways Beds, their total thickness there 

is 74 ft. The only comparable record is that of the deep boring at Swindon, 

where the Kellaways Beds were said to be 60 ft. thick, and where both of the 

zone fossils were found. 4 

The best locality for studying the fossiliferous facies of the rock is still the 

old type-locality at Kellaways, 2 miles north-east of Chippenham. The 

exposures are disappointing on a casual visit, consisting of mossy banks and 

projecting rocks in the side of the River Avon, and to study them it is necessary 

to stand in the river with waders. The best sections are in the banks of 

an artificial watercourse north-east of Peckingell Farm, about half a mile 

below Kellaways Bridge, and also in the main river near by. The rock is from 

3 ft. to 6 ft. thick, the upper part being a mass of fossils embedded in brownish 

micaceous sandstone. Both the palaeontological and the lithological facies 

are very suggestive of some of the Upper Cornbrash. In order of abundance 

the principal fossils are: Microthyris ornithocephala (Sow.), Gryphcea bilobata 

1 1925, T.A., vol. v, p. 66. (The lower record attributed to him on the same page is a 

mistake and should be deleted; see the errata.) 

2 A. Harker, 1884, Proc. Cots. N.F.C., vol. viii, pp. 176-87. 

3 L. Richardson, 1922, Geol. Mag.y vol. lix, pp. 354-5. 

4 H. B. Woodward, 1895, J.R.B., p. 37.

OXFORD CLAY: OXFORD 347 

Sow. (some very small, not much larger than the Microthyrid), Pleuromya 

recurva (Phil.), Rhynchonelloidea socialis (Dav.), Modiola bipartita (Sow.), 

Camptonectes lens (Sow.), Pseudomonotis sp. and Oxytoma expansa (Phil.), with 

others less common. In William Smith's time the rock was quarried for roadmetal 

in several small pits about Kellaways, but these have long since been 

filled in or obliterated. Two brickyards south of Chippenham still show 

sections of the upper part, more sandy and less fossiliferous. Gryphcea bilobata 

is nearly everywhere the commonest fossil. 1 

(c) Oxford to Bedford and Huntingdon 

The Oxford Clay continues from the Vale of the White Horse with little 

appreciable change past Oxford and under the low-lying tracts of Bedfordshire 

to the Fens. Everywhere it forms flat and heavy land, except where 

along the northern or western fringe the Kellaways Rock is developed, rising 

into a low escarpment above the Cornbrash. Through Wiltshire and Berkshire 

the highest zones build the base of the ridge of Corallian sands and 

limestones, and here their outcrop is very narrow and exposures are lacking. 

These conditions are changed somewhat to the east of Oxford owing to the 

disappearance of the Corallian, or rather its passage into clay, and the clays 

immediately underneath it have a wider outcrop and are occasionally seen in 

brickyards. 

There are no natural lines of demarcation between adjacent parts of the 

clay belt from the Dorset coast to the Market Weighton Axis, but since this 

tract is too large to describe as a whole, arbitrary divisions have to be chosen. 

A convenient district for separate treatment is the type locality of Oxford and 

the adjoining counties to the east, where the zonal sequence has been elucidated 

in some detail. It is a district too, which is remarkable for an easterly 

overstep of the upper zones of the Oxford Clay by the equivalents of the 

Corallian (Argovian). This unconformity was detected by Prof. A. Morley 

Davies, who showed in 1916 that about Ampthill, Sandy and Woburn the 

martelli zone of the Argovian rests directly on the renggeri zone of the Oxford 

Clay, the whole of the Cardioceratan and part of the Quenstedtoceratan strata 

having been cut out (fig. 62, p. 348). 

At Oxford the total thickness has been estimated at about 450 ft. It is 

probable that the easterly overstep of the Corallian in Buckinghamshire and 

Bedfordshire reduces the Oxford Clay considerably, but still farther east it 

probably thickens again, for 300 ft. was proved at Bluntisham, and H. B. 

Woodward considered 500 ft. a reasonable estimate for the Huntingdon 

district. 2 

Immediately north-east of Oxford the Oxford Clay forms the low-lying 

tract known as Otmoor, which was an undrained swamp until 1825-30, and 

is still waterlogged for a large proportion of the year. The highest zones crop 

out round the southern fringe of Otmoor and about the projecting hills at 

Brill. 

1 A representative selection of the ammonite fauna of the Kellaways Rock type-locality has 

been figured from time to time by Buckman, T.A., pis. ccxxvin, CCLV, CCLXXV, CCXC, CCXCIII, 

CCXCIV, CCCLXXIX, DVII, DXXXVII, DXXXVIII, DLXXXVI, DLXXXVII, DCXIV, and a revised list of all 

the fossils by J. Pringle and S. S. Buckman is to be found in the 'Geol. Marlborough', 1925, 

Mem. Geol. Surv.t pp. 11-12. Another revision is needed already, however. 

2 iS95yJ.R.B., p. 56.


SUMMARY OF THE OXFORD CLAY ABOUT OXFORD 

Praecordatum Zone. The actual junction with the Lower Calcareous 

Grit can nowhere be seen, though it was formerly exposed in a brick-pit at 

New Marston, to the west of the Cherwell (in the outskirts of Oxford), and 

has several times been pierced by wells. One well was described by Prof. 

Morley Davies at Studley, 1 where the Arngrove Stone (basal Corallian, 

cordatum zone) rested on clay with finely-ribbed Cardiocerates of the tenuicostatum 

type, which he found in several places to characterize the upper part 

of the prcecordatum zone. He also described the same horizon in the G.W.R. 

WHEATLEY ASHENDON JUNCTION AMPTHILL 

FIG. 62. Diagrammatic section from the borders of Berkshire and Oxfordshire into Bedfordshire 

showing the unconformity at the base of the martelli zone. (Adapted from Morley 

Davies, Geol. Mag., 1916, p. 399, with alterations to the Corallian part.) 

cutting immediately north of the tunnel in Rushbeds Wood, near Brill, 

where the ammonites 2 were associated with Gryphcea dilatata Sow. and its 

variety discoidea Seeley. 3 

The best section of the prcecordatum zone is opened at a lower level in the 

zone, at Studley (or Horton, or Horton-cum-Studley) brickyard, by the 

roadside \ mile south-east of the village. Ten feet of clay are seen, in which 

are hundreds of large Gryphaeas. When collected in large numbers they can 

be arranged in lines connecting up several forms usually regarded as distinct 

species, especially G. dilatata Sow., G. discoidea (Seeley), G. controversa 

Roem., and G. exaltata Rollier. The pit is principally noteworthy, however, 

for yielding numerous well-preserved Cardiocerate ammonites in the form of 

attractive brown or ochreous casts, which display the suture lines to advantage. 

They include C. prcecordatum R. Douv., C. cardia Buck., Q. costellatum 

Buck., C. cf. quadratoides Nikitin, all species of rather stout proportions 

as compared with the fine-ribbed tenuicostatum-like species found in the higher 

part of the zone. There are also minute Perisphinctids, and the genus of 

Cardioceras-like ammonites which Buckman named after this locality, Hortoniceras. 

Prof. Morley Davies records that the prcecordatum zone was also 

exposed in the brickyard near Quainton Road junction, and in a cutting on the 

Great Central Railway north of Wotton Railway Station (ENE. of Brill). 4 

Renggeri and Lamberti Zones. These zones are the least often 

1 A. M. Davies, 1907, Q.J.G.S., vol. lxiii, p. 40. 

2 Originally recorded as C. cordatum and distinguished later. 

3 A. M. Davies, 1907, P.G.A., vol. xx, p. 185. 

4 A. M. Davies, 1916, Geol. Mag. [6], vol. iii, p. 397.

OXFORD CLAY: OXFORD 349 

seen of all in the district, but they were studied by Prof. Davies in the 

Ludgershall railway-cutting north of Brill and numerous fossils were collected. 

There was a well-marked zone of Creniceras renggeri, but no evidence 

for a separate lamberti zone was seen, Quenstedtoceras and Creniceras 

being mixed throughout. 1 Prof. Davies pointed out that, except for the 

absence of Phylloceras, the greater abundance of Quenstedtoceras and the 

presence of Kosmoceras, there was a remarkable resemblance between the 

fauna of this zone at Ludgershall and equivalent beds in the Bernese Jura, 

described by de Loriol. 2 The Bernese fauna was later obtained at the same 

horizon in the borings for coal in Kent. 

The renggeri zone is also worked in the upper part of the brickfield at 

Woburn Sands and either the renggeri or the lamberti zone again at Sandy, 

Beds., in the region where the higher strata are missing and the martelli clay 

of the Corallian rests upon it non-sequentially. At Oxford the renggeri and/or 

lamberti zones were at one time exposed at Summertown, but the great clay 

pit is now derelict. There are still indications of the base of the lamberti 

zone in the form of rare occurrences of Quenstedtoceras in the very top of the 

pit at Wolvercote. 

Athleta Zone. The athleta zone is well exposed in the large brickyard at 

Wolvercote, on the north side of Oxford. 3 Peltoceras athleta occurs near the 

present base of the pit, in a band of clay z\ ft. thick, overlying a 6-in. band of 

cementstone. Dr. J. Pringle restricts the zone to these two beds, giving it 

a thickness of only 3 ft. The characteristic fauna besides the zone fossil 

comprises the small, much incoiled, and almost equilateral Gryphcea lituola 

Lamk., together with the brachiopods Aulacothyris bernardina (d'Orb.) and 

Rhynchonella spathica (Lamk.). The same Gryphcea and Aulacothyris were 

found by Prof. Davies to characterize the zone in the Ludgershall railwaycutting 

and again in Woburn Green brickyard. At Wolvercote 18 ft. of clays 

with a band of cementstone succeed the horizon at which this fauna is found, 

thus comprising the greater part of the section now exposed. The fauna 

includes three species of Peltoceras, but not apparently P. athleta; and as it is 

chiefly characterized by Kosmocerates of the pronice and subnodatum types 

Dr. Pringle has considered it a separate zone of K. pronice Teisseyre. Its 

separation has not, however, been substantiated by studies in other districts, 

and it is more convenient to consider it, on the strength of its Peltocerates, as 

a part of the athleta zone. The range of Kosmoceras pronice, according to 

Brinkmann, extends from the top of the athleta zone down to the upper limit 

of the true castor and pollux (our reginaldi) zone. 

Duncani to Jason Zones. The Lower Oxford Clay or typical Kosmoceratan, 

from the duncani zone down to the top of the Kellaways Rock, is 

nowhere well exposed near Oxford, though the top of the duncani zone is 

sometimes reached in the base of the Wolvercote brickyard and was formerly 

exposed in the Summertown pit. The presence of the jason zone was proved 

in 1924 by a boring at Gosford Hill, Kidlington, where Dr. Pringle found 

Kosmoceras stutchburii (Pratt) and K. ejfulgens Buck. 4 (? = jason). 

1 A. M. Davies, 1916, loc. cit., p. 396. 

2 1898-1900, Mem. Soc. pal. Suisse, vols, xxv-xxvii. 

3 J. Pringle, 1926, 'Geol. Oxford', 2nd ed., Mem. Geol. Surv., p. 36. 

4 J. Pringle, 1926, loc. cit., p. 35; and S. S. Buckman, 1925, T.A., pi. DXCVII.


The best exposures of the Oxford Clay in the central part of England (south 

of the Peterborough district) are in the lower zones at Calvert, near Claydon, 

5 miles south of Buckingham (PI. XV) and at Bletchley. Here enormous 

brick-pits have grown up since the coming of the railway in 1898, when a 

branch brickworks was started at Calvert by Messrs. Itter of Peterborough. 

The beds dug are the shaly clays of the reginaldi and jason zones, with their 

hundreds of crushed and iridescent ammonites. The deep borings, for which 

Calvert is renowned, were started, one in the floor of the main pit, about 

70 ft. below surface, the other nearly at ground level. 1 They passed through 

32 ft. of clays below the floor of the pit, making 97 ft. of Oxford Clay in all. 

The only ammonites encountered were Kosmoceras sedgwickii (Pratt) (? — 

jason Rein.), and K. ? stutchburii (Pratt); and judging by these fossils and 

because the clays rested directly on the Bathonian limestones, it was presumed 

that the Kellaways Beds were missing, as was definitely the Cornbrash. 

In view of the great thickness of the clays, however, the possibility must not 

be lost sight of that the Kellaways Beds may be represented but unfossiliferous. 

The lower zones of the Oxford Clay are repeatedly well exposed in extensive 

brickworks at Charndon and Bletchley, Bucks., and Wootton Pillinge (Stewartbury), 

Beds. At the last two places the pits or "knot holes' are of vast extent and 

present a vertical face 70 ft. deep, but in spite of these facilities for study, the 

elucidation of the successive faunas still remains unattempted. The type 

specimen of Kosmoceras duncani, figured by Sowerby, came from St. Neots. 

Calloviense and Koenigi Zones (KELLAW T AYS BEDS). The Kellaways Beds 

seem to be feebly developed from the neighbourhood of Cirencester through 

the Thames Valley, for they have hardly ever been exposed. 

In the Shipton-on-Cherwell railway-cutting north of Oxford, 5 ft. of yellow 

and grey sands overlay 10 ft. of clay above the Cornbrash, and a similar section 

is still visible at Akeley brickyard, north of Buckingham. At the latter place 

A. H. Green many years ago recorded Proplanulites koenigi. 2 

About Bedford the Kellaways Beds regain considerable importance. 

Numerous sections have shown in the past that the sands are about 10 ft. 

thick and contain large concretionary doggers of grey-hearted sandstone like 

those at South Cerney near Cirencester, and yielding S. calloviense, Gryphcea 

bilobata, Oxytoma expansa, Pleuromya recurva, Camptonectes lensy Entolium 

demissum and lignite. Beneath is about the same thickness of stiff Kellaways 

Clay, from which Gowericeras gowerianum, mentioned in the old lists, probably 

came. The beds can still be seen in the waterworks pit, but one of the best 

exposures was in the Midland Railway cutting north of Oakley Railway Station, 

now overgrown. 

A boring at Bletchley in 1887 encountered pebbles and blocks of granitic 

rocks in what Jukes-Browne, Cameron and later H. B. Woodward supposed 

to be the Kellaways Rock, thickened to 54 ft. This view was accepted until 

1913, when the Calvert borings, not many miles away, enabled Prof. Morley 

Davies to revise the interpretation of the Bletchley record and to show that 

the granitic rocks are much more likely to have belonged to the base of the 

1 The site of the boring from which gas rose under pressure has been covered up by tipheaps. 

2 A. H. Green, 1864, 'Geol. Banbury, Woodstock, 8cc.\ Mem. Geol. Surv.} p. 41.


Lower Oxford Clay, Calvert Brickyard, Bucks. 

The photograph shows the face being worked by hand in stages, a system now replaced by steam ^ 

excavators (of which a small one is seen on the top, removing overburden). ^ 

M

OXFORD CLAY: PETERBOROUGH 351 

attenuated Lower Lias, on, or not far above, the Palaeozoic floor. 1 This 

was in accordance with the expectations of Prof. Kendall, who had in 1905 

suggested that formations lower than the Kellaways were probably present. 2 

(d) Peterborough and the Fens to the Humber 

The Oxford Clay underlies large areas of the Fens, sometimes protruding 

through the alluvium as islands, as at Whittlesey and Ramsey. Northward 

through Lincolnshire the outcrop gradually narrows, but there is only a 

gradual decrease in thickness towards the Humber, for in North Lincolnshire 

the thickness is still in the neighbourhood of 300 ft. Towards the east 

attenuation is more rapid. A boring at Southery, in the Norfolk Fens, proved 

only 200 ft., with complete absence of the Kellaways zones. 3 

A large proportion of the outcrop is masked by deep deposits of alluvium 

and Drift. This applies especially to the Fenland and its borders, and also to 

the valley of the Ancholme, draining into the Humber in the north. The few 

railway-cuttings of the past have all been opened along the western margin 

of the outcrop, and have shown only the lowest zones of the clay and the 

Kellaways Beds. On the whole, exposures of the Upper Beds are small and 

scattered, and with the extinction of local brick-making industries most of 

the small pits mentioned by the earlier writers have become grassed over. 

The Middle and Lower Oxford Clay, at least in the Peterborough district, 

are now exposed far more completely than ever before. This is due to the 

growth within the present century of an enormous brick-making trade, 

centred around that town on account of the good railway transport which it 

affords. Fletton, Kingsdyke, Yaxley, and indeed the whole landscape in the 

vicinity of Peterborough, are now dominated by a forest of chimneys, and the 

very name of Peterborough recalls bricks. The huge clay pits, like those at 

Calvert but duplicated many times, have to some extent compensated the 

geologist for the loss of the local exposures whose decline and extinction all 

this centralization has brought about. But the compensation is not all that 

could be desired, for whereas the old local industries gave information concerning 

many zones over the length and breadth of the outcrop, the new 

excavations, although far larger, all show about the same part of the formation 

and they are concentrated around one locality. However, the opportunities for 

studying the succession of ammonite faunas which the Peterborough brick 

industry has provided are held to be the best in Europe, and a study of them 

has revolutionized our knowledge of the lower zones of the Oxford Clay. 

For records of the highest zones, in the absence of recent research, and in 

view of the probability that investigations would not now yield much new 

information, it is necessary to resort to the accounts of Judd and Roberts and 

other writers of the last century. 

J. W. Judd recognized an upper group of clays 'with Ammonites of the 

group of the cordati\ but stated that it was usually concealed by Drift. This 

division was exposed to a depth of 40 ft. north of Bardney Railway Station, east 

of Lincoln, and judging from the ammonites recorded (allowing for archaic 

1 H. B. Woodward, 1895, J.R.B., 

P. 332. 

p. 49, with refs.; A. M. Davies, 1913, Q.J.G.S., vol. lxix, 

2 P. F. Kendall, 1905, Report of Royal Commission on Coal Supplies, p. 195. 

3 J. Pringle, 1923, Sum. Prog. Geol. Surv. for 1922, pp. 126-39.


nomenclature) it represents the prcecordatum zone and perhaps some slightly 

earlier strata. 1 * Ammonites cordatus' and 'A. lamberti' were also recorded from 

a small brickyard at Langworth, north-east of Lincoln, where the base of the 

prcecordatum and the top of the renggeri or lamberti zones may be presumed to 

have been seen. The lamberti zone also appears to have been worked at 

Timberland, Lines. There are records of * Ammonites' [.Hecticoceras] hecticus 

at Langworth 2 and near Cambridge, in which neighbourhood also Cardiocerates 

of the prcecordatum zone abound in the Oxford Clay; while Prof. 

Davies informs me that he has seen specimens of C. renggeri from St. Ives. 

The old records are too untrustworthy to base on them any conclusions as 

to the presence or absence of separate zones of renggeri and lamberti, but 

modern evidence is forthcoming at Eye Green, north-east of Peterborough. 

Here Dr. Neaverson has described the clays at the top of the pit as yielding 

a fauna of the coarser-ribbed and feebly-rostrated Quenstedtocerates of the 

type of Q. lamberti, without Creniceras but with Hecticoceras. 3 This he interprets 

as confirmation of Buckman's suggestion that there should be a lamberti 

horizon below and separate from the renggeri zone. Thus the evidence at Eye 

Green contradicts that of the Buckinghamshire railway-cuttings examined by 

Prof. Morley Davies and illustrates how different zonal schemes are likely to 

be evolved by the several palaeontologists working in different districts. 

The whole of the remaining zones down to the base of the Oxford Clay are 

exposed several times in the great brick pits around Peterborough, at Eye 

Green, Kingsdyke, Fletton, Farcet, &c. There is wide difference of opinion 

concerning the interpretation of the detailed ammonite succession. In 1925 

Dr. E. Neaverson published a valuable paper in which he set forth a zonal 

classification as follows, in descending order: 4 

lamberti 

athleta 

duncani 

castor 

coronatum 

elizabethce 

conlaxatum (with jason) 

In the following year Dr. R. Brinkmann, having obtained a grant from the 

Academy of Sciences at Gottingen, spent some two months at Peterborough 

collecting the ammonites in situ and studying them by the most painstaking 

statistical methods. In 1929 he published a lengthy report on the results, 

followed by a monograph on the genus Kosmoceras. 5 The report contains 

250 pages, 129 tables and 55 diagrams, in which the object, methods and conclusions 

are set forth. Since they concern the whole principles of the zonal 

classification of the Oxford Clay, they must receive attention before any more 

can be said. 

Brinkmann set out with the object of determining accurately the succession 

1 In confirmation of this Prof. Davies informs me that he has purchased renggeri forms 

bearing Bardney labels. 

2 J. W. Judd, 1875, 'Geol. Rutland*, Mem. Geol. Surv., pp. 232-9. 

3 E. Neaverson, 1925, P.G.A., vol. xxxvi, pp. 27-37. 

4 E. Neaverson, 1925, loc. cit. 

5 R. Brinkmann, 1929, Abh. Gesell. Wiss. zu Gottingen, N.F., vol. xiii, parts 3 and 4, 

373 PP-» a ^d see review in Geol. Mag., 1931, vol. lxviii, pp. 373-6.


of the innumerable forms of Kosmoceras contained in the clays, using minute 

quantitative methods to define them. He confined his attention to three of 

the pits, those of the London Brick Co. south of Fletton and between Kingsdyke 

and Whittlesey, and that of the Itter Brick Co. at Kingsdyke. These 

overlap so as to provide a continuous section of 13 metres (43 ft.), which he 

divided into centimetres for purposes of collecting, thus obtaining 1,300 

horizons. From numbered horizons in this section he collected and measured 

3,000 specimens. At the same time he paid particular attention to the lithology 

of the various beds with the object of discovering, if possible, the conditions 

under which they were deposited; and, as already mentioned in 

Chapters I and III, his conclusions are of considerable interest, especially 

because he was able to work with lineages. 

Methods of determining ammonite evolution upon a quantitative basis 

naturally depend upon the measurement and documentation of the characters 

of large numbers of individuals at each horizon. The average variation in any 

particular character at a given horizon is taken by Brinkmann to indicate 

a definite phase, and comparison of the figures for successive horizons shows 

the rate of evolution per unit thickness of strata. The two chief potential 

sources of error in this operation are: first, that the measurements are largely 

made upon crushed material; secondly, that the assumption is involved that 

the assemblage of individuals preserved in any particular bed is a truly representative 

selection of the living population. Brinkmann argues that neither 

source of error is so serious as to interfere with the conclusions. In the first 

place he finds that the errors in measurements due to distortion of the shells 

are negligible in comparison with the degree of individual variation. In the 

second place he believes that, although the assemblage preserved at any given 

level may be selected posthumously by wave or current action, it is safe to 

assume as a working hypothesis that it truly represents the living population. 

He emphasizes that the greater concentration of ammonites in the shell-beds 

is purely an artificial one, due ultimately to tectonic disturbances and not to 

fluctuations in the population. 

The conclusions bearing upon evolution and ammonite systematy to which 

these considerations lead are of the highest importance. Brinkmann recognizes 

at Peterborough only thirteen species of Kosmocerates, belonging to 

four lineages, which he regards as natural subgenera of the single genus 

Kosmoceras. In the synonymy of the genus he places twenty-one of Buckman's 

genera. 

This simplification results from the rational conception of the subgenus as 

an evolutionary chain or lineage, in which the species are successive links, of 

arbitrarily-chosen but uniform length. The four subgenera, Anakosmoceras, 

Zugokosmoceras, Spinikosmoceras (all due to Buckman) and Kosmoceras sensu 

stricto, he finds evolved continuously side by side. The Oxford Clay could 

therefore be rationally zoned by any of these subgenera, successive species 

being taken to mark successive zones (true biozones, as defined above, p. 22), 

but not by all of them together, as is usually done. 

The principal systematic rearrangements made by Brinkmann, affecting 

Dr. Neaverson's zonal table, are the following: he regards K. conlaxatum S. 

Buck., the zonal index to Dr. Neaverson's lowest zone, as synonymous with 

K. jason (Rein.); he regards K. elizabethce (Pratt), the index to the second zone,


as synonymous with the true K. ornatum Schloth., of which he selects and 

figures a lectotype; K. castor, used as index to Dr. Neaverson's fourth zone, 

he considers a misidentification, and declares that the true K. castor (Rein.) 

lived contemporaneously with Erymnoceras coronatum (index of Dr. Neaverson's 

third zone). Further, he states that K. ornatum has hitherto been misidentified 

and that K. ornatum auctt. is synonymous with K. spinosum (Sow.); 

finally that K. stutchburii (Pratt), which has recently been chosen by Prof. 

Davies as index of his lowest zone, is to be regarded as a synonym of K. 

gulielmii (Sow.). (Buckman placed these last not only in different genera, but 

even in different families.) 

Clearly if these conclusions are to be accepted, profound modifications of 

the previous zonal partition of the Lower Oxford Clay must be made. 

Brinkmann retains the following zonal table, using the various overlapping 

subgenera, but eliminating overlapping species so far as possible: 

Q. lamberti . . corresponding to Neaverson's lamberti zone 

K. spinosum (Sow.) ,, ,, athleta zone 

(= ornatum Quenst.) 

K. castor and pollux" fduncani 

K. jason 

| castor 


indices in one country may often be valueless in another, so that it is impossible 

to restrict ourselves to a given lineage. 

Thus we can admit that neither of Pratt's names, elizabethce and stutchburii, 

should be retained, and that Buckman's conlaxatum is a synonym of jason 

Reinecke, and still legitimately adhere to the slightly modified zonal table 

adopted here, viz.: 

Zone of C. prcecordatum 

C. renggeri 

,, Q. lamberti 

" K duncani} ^~ s P^ nosum zone Brinkmann) 

,, E. reginaldi (= coronatum zone of Buckman and Neaverson) 

„ K. jason (= conlaxatum+elizabethce zones of Neaverson 

= castor and pollux-\-jason zones of Brinkmann). 

SUMMARY OF THE SUCCESSION AT PETERBOROUGH 1 

Of the succession of clays and their faunas comprised within these zones 

as exposed at Peterborough, Dr. Neaverson has given a clear if brief account. 

Athleta Zone. The clays with large Peltocerates, some of which can be 

referred to P. athleta (Phil.), contain the same fauna as at Oxford. The most 

abundant fossils are the Gryphcea, best identified as G. lituola Lamk., and also 

the brachiopod Aulacothyris bernardina (d'Orb.). It is noteworthy, however, 

that Kosmocerates of the pronice type do not here occur above this horizon as 

at Oxford but below, in the clays assigned by Neaverson to the duncani zone. 

This seems to furnish a good reason against the retention of a pronice zone, 

and indeed Brinkmann declares that the species ranges down to the base of 

Neaverson's elizabethce zone. 

Duncani Zone. The clays of this zone are principally characterized by 

abundant pyritic casts of ammonites, among the most common of which are 

species of the subgenus Kosmoceras sensu stricto (K. spinosum (Sow.), and K. 

cf. gemmatum (Phil.), K. duncani, &c.), together with K. cf. pronice Teiss. 

There are also some pyritic casts of lamellibranchs, especially Nuculana cf. 

phillipsi (Morris), N. cf. longiuscula (Merian) and N. cottaldi de Lor. Belemnopsis 

hastata begins a little below this zone and ranges upwards. 

Reginaldi Zone. Dr. Neaverson says: 2 

'The only substantial evidence obtained for the presence of this zone is the 

occurrence of large specimens of Erymnoceras reginaldi (Morris) in Messrs. Itter's 

brickyard ij miles west of Whittlesey. The specimens occur in shales similar to 

those of the elizabethce zone but were not in situ and the position of the zone in the 

section could not be located. A poor fragment from similar shale at Fletton is also 

referred to this species.' 

According to Brinkmann K. duncani (Sow.) ranges down to below the reginaldi 

horizon; but he misinterpreted K. duncani (see note opposite Plate XXXVII, 

fig. 6). About this level is the maximum of Cylindroteuthis puzosi. 

Jason Zone. This zone chiefly consists as usual of a considerable thickness 

of shaly clay full of compressed Kosmocerates. The lithology of the shales, 

1 Based on E. Neaverson, loc. cit., 1925. 

2 1925, loc. cit., p. 32.


and also many of the species of ammonites and their preservation, are the 

same as in the Christian Malford railway-cutting and the brickworks at 

Calvert. Nucula nuda is also abundant and was used by Judd as index species. 

Dr. Neaverson called this the elizabethce zone (= ornatum Schloth. non auctt. 

according to Brinkmann) and separated as the conlaxatum ( = jason) zone 

some basal clays which form the floor of the brickfields at Fletton and Kingsdyke. 

These basal clays are not favourably exposed for study, but they 

contain large septaria which are thrown out during the construction of 

shallow drainage trenches, and from them many ammonites can be collected, 

uncrushed and excellently preserved. The principal forms are varieties of 

K. (A.) gulielmii (Sow.) and the true K, (Z.) jason (Reinecke). 'Speaking 

generally/ Dr. Neaverson remarks, 'the series contains forms which are 

highly ornamented, and others that show loss of sculpture correlated with 

a close approximation of the septa as growth proceeded. 5 Cylindroteuthis 

puzosi also occurs in the septaria. 

Calloviense and Koenigi Zones (KELLAWAYS BEDS). Dr. Neaverson describes 

a small brick-pit north-west of the railway-bridge near Werrington, 

on the main road north-north-west of Peterborough, where about 4 ft. of 

dark-blue unfossiliferous clay passes up into a thin band of soft concretionary 

sandstone, which contains part of the fauna of the Kellaways Rock. Gryphcea 

bilobata, Oxytoma sp. and Entolium demissum are recorded, but no ammonites. 

Far better sections of the Kellaways Beds have been seen from rime to time 

along the western margin of the outcrop, where the Kellaways Rock makes 

a surface feature and has been cut through during the construction of some 

of the railways. In a cutting south-west of Bourn, on the Bourn and Saxby 

line, H. B. Woodward in 1892 saw the 'dense grey shaly clay with selenite, 

lignite and numerous flattened ammonites' of the jason zone, with a band of 

septaria 10 ft. from the base (perhaps corresponding to that at Peterborough), 

resting on 2 ft. of calcareous, flaggy, blue-hearted sandstone with abundant 

Gryphcea bilobata and belemnites—the Kellaways Rock. This was in turn 

separated by a clay from the Cornbrash. 1 A nearly similar section was 

described by Morris in 1853 in the Casewick cutting. Here Sigaloceras 

calloviense was recorded from the Kellaways Rock, together with most of the 

characteristic lamellibranchs. The rock, which was ferruginous and passed 

into brown sandy clay, was separated from the Upper Cornbrash by 10 ft. 

of 'dark, laminated, unctuous' Kellaways Clay, in which abundant Macrocephaloid 

ammonites were said to occur. 2 

The sandy development of the Kellaways Rock, always with Gryphcea bilobata 

and certain belemnites, persists at about the same horizon throughout 

Lincolnshire to the Humber. It continues to be separated everywhere from 

the Cornbrash by a clay, which varies from 2 ft. to 18 ft. At Brigg a boring 

proved 2 ft. of Kellaways Rock, with 18 ft. of clay below, while a little to the 

south a considerable portion of the clay becomes sand, locally consolidated 

into rock, which may reach a thickness of 20 ft. The greatest recorded 

thickness of 25 ft. was proved at Sudbrooke, near Lincoln. 3 


2 J. Morris, 1853, Q.J.G.S., vol. ix, p. 333. 

3 H. B. Woodward, 1895, J.R.B., pp. 65-7, with refs.

OXFORD CLAY VERTEBRATA 357 

VERTEBRATA OF THE OXFORD CLAY OF PETERBOROUGH 

For over thirty years two brothers, C. E. and A. N. Leeds, of Peterborough, 

assiduously collected the bones of vertebrates from the Oxford Clay of the 

rapidly-growing brickfields. The collections so formed became renowned, 

providing subject-matter for numerous papers by Seeley, Lydekker, Hulke, 

C. W. Andrews and Sir Arthur Smith Woodward. 1 They were eventually 

purchased by the British Museum and have been described in two magnificent 

volumes by the late C. W. Andrews. 

The exact zonal positions of the specimens are not recorded, but the whole 

rich fauna must have been yielded by some part of the jason-athleta zones inclusive 

and the majority undoubtedly came from the jason zone. The skeletons 

are said to have 'occurred spread over well-defined old floors in the clay, and 

could thus with care be recovered almost in their entirety'. 2 This suggests 

that they occurred on the horizons corresponding with breaks in sedimentation, 

described by Brinkmann. 

An excursion of the Geologists Association visited Peterborough and the 

Leeds Museum in 1897, under the direction of A. N. Leeds and Sir Arthur 

Smith Woodward. In the report Sir Arthur gave a valuable summary of the 

features of the vertebrate fauna, 3 w T hich he has very kindly re-written, bringing 

it up to date (1932), especially for insertion here: 

'The land-reptiles (Dinosauria)', he writes, 'are represented only by imperfect 

skeletons without the head, and by one portion of lower jaw. They include one 

Sauropod (Cetiosauriscus leedsi) about 60 ft. in length, and two species of an 

armoured Orthopod which have been referred to Stegosaurus, a genus best known 

from the Upper Jurassic of North America. The lower jaw may belong to one of 

the latter species; and a small femur seems to be referable to an Orthopod related 

to the Wealden Iguanodon. The Crocodiles Steneosaurus and Metriorhynchus are 

represented by many nearly complete skeletons of several species. 4 Both are marine, 

and Metriorhynchus has no bony armour. The Pterodactyles, as might be expected 

from their mode of life, are scarcely known; but it is very curious that no trace of 

a Chelonian has hitherto been discovered. The Sauropterygia predominate, and 

include both the small-headed Plesiosaurians and the large-headed Pliosaurians, of 

several genera. There are skeletons of individuals of all ages, from the very young 

to the extremely old. The Ichthyopterygia are represented by an almost toothless 

ally of Ichthyosaurus with comparatively broad and flexible paddles (Ophthalmosaurus). 

'Fish remains are very abundant, and they are important as supplementing our 

knowledge of the Upper Jurassic fauna in the Lithographic Stone of Germany, 

France, and Spain. Whereas the Continental fossils display the general contour of 

the various fishes embedded in very hard limestone, the specimens in the Oxford 

Clay were originally macerated and buried in soft clay, from which the different 

bones and teeth can be washed and examined separately. There are fine groups of 

teeth of Hybodus found in association with the jaws of this shark. There are also 

many still finer groups of the teeth named Strophodus, in undoubted association 

with the fin-spines named Asteracanthus and the hooked head-spines named 

Sphenonchus. Chimaeroids are known only by dental plates and fragments of spines. 

1 See bibliography. 

2 A. N. Leeds, 1897, P.G.A., vol. xv, p..189. 

3 A. Smith Woodward, 1897, loc. cit., p. 190, with full bibliography. 

4 Andrews has described four new species (1909, Ann. Mag. Nat. Hist. [8], vol. iii, pp. 

299-308).


The remains of Ganoid fishes are especially fine and numerous, and those of 

LepidotuSy the Pycnodont Mesturus, Caturus, EurycormuSy and Hypsocormus have 

added much to our knowledge of the skull in these primitive types. Leedsia 

problematica is a gigantic Pachycormid fish, with a forked tail 9 feet in span.' 

LIST OF THE OXFORD CLAY VERTEBRATA FROM PETERBOROUGH 1 

Cetiosaur[isc]us leedsi (Hulke) 

Omosaurus durobrivensis Hulke 

A large Stegosaurian 

Camptosaurus leedsi Lyd. 

Sarcolestes leedsi Lyd. 

Rhamphorhynchus sp. 

Ophthalmosaurus icenicus Seeley 

Murcenosaurus leedsi Seeley 

M. durobrivensis Lyd. 

M. platyclis Seeley 

Picrocleidus beloclis (Seeley) 

P. sp. 

Tricleidus seeleyi Andrews 

Cryptocleidus oxoniensis (Phil.) 

Hybodus obtusus Ag. 

Aster acanthus ornatissimus Ag. 

var. flettonensis A. S. Woodw. 

Pachymylus leedsi A. S. Woodw. 

Brachymylus altidens A. S. Woodw. 

Ischyodus egertoni (Buckland) 

I. beaumonti Egerton 

Lepidotus leedsi A. S. Woodw. 

L. latifrons A. S. Woodw. 

L. macrocheirus Eg. 

Reptilia. 

Pliosaurus ferox (Sauv.) 

Simolestes vorax Andrews 

Peloneustes philarcus Seeley 

P. evansi (Seeley) 

Metriorhynchus superciliosus Desl. 

M. brachyrhynchus Desl. 

M. sp. 

Suchodus durobrivensis Lyd. 

Dacosaurus sp. 

Steneosaurus edzvardsi Desl. 

S. leedsi Andr. 

S. durobrivensis Andr. 

S. obtusidens Andr. 

Mycterosuchus nasutus Andr. 

Pisces. 

Heterostrophus sp. 

Mesturus leedsi A. S. Woodw. 

Caturus sp. 

C. sp. 

Osteorachis leedsi A. S. Woodw. 

Eurycormus egertoni (Eg.). 

Hypsocormus leedsi A. S. Woodw. 

H. tenuirostris A. S. Woodw. 

Leedsia problematica A. S. Woodw. 

Pholidophorus sp. 

II. THE MARKET WEIGHTON AXIS 

North of the Humber the Oxford Clay becomes very thin. Its total thickness 

is not known, but the amount of shaly clays between the top of the 

Kellaways Rock and the top of the Kimeridge Clay measures rather over 

100 ft. near South Cave, and probably not more than half of this is accounted 

for by Oxford Clay. Only the basal portion has been exposed, and from the 

recorded Kosmocerates (K. elizabethce and K. comptoni) this would seem still 

to belong to tht jason zone. 

The section which showed the base of the Oxford Clay is a deep cutting on 

the Hull and Barnsley Railway, made in 1883, at Drewton, north of South 

Cave. It also laid bare a fine section of the Kellaways Rock, which was 

described in detail by Keeping and Middlemiss. 2 Immediately below the clay 

were 10 ft. of hard, brown, ferruginous sandy beds, crowded with fossils, 

especially Gryphcea bilobata, Pseudomonotis sp., Rhynchonelloidea socialis and 

belemnites, below which were 45 ft. or more of sands, the upper part brownish 

1 C. W. Andrews, 1910, Descr. Catal. Marine Reptiles Oxford Clay (B.M.), vol. i, p. viii. 

2 1883, Geol. Mag. [2], vol. x, pp. 215-21.

OXFORD CLAY: SOUTH YORKSHIRE 359 

or yellow and containing two lines of large doggers, the lower parts pure 

white and highly micaceous. The sands were nearly barren except for a band 

about the middle which was riddled with hollow casts of belemnites. 

The section of Kellaways Rock in the Drewton cutting is typical of all the 

region between the Humber and Newbald, where the outcrop is lost beneath 

the Chalk. The only variation of note is in the thickness. The sands are, or 

have been, dug in several pits about Newbald. The largest has been disused 

for some years, but at the top can still be seen the base of the reddish-brown 

soft sandstone, crowded with Gryphcea bilobata and belemnites. In a pit near 

Brough were found a number of bones of a saurian, identified as Cryptocleidus. 1 

The zonal position of these sands long remained doubtful. Messrs. 

Keeping and Middlemiss recorded 'Ammonites modiolaris, A. koenigi and A. 

gowerianus' from the fossiliferous upper 10 ft., but they also mentioned 'A. 

duncani y and even 'A. marice\ so that probably not much reliance can be 

placed upon their records. Buckman in 1922 figured a Macrocephalitid form 

from the Drewton cutting under the new generic name Catacephalites, and 

he considered it to indicate that the Kellaways Rock of South Cave was older 

than that in other parts of England. 2 Three years later, however, he announced 

that the same forms had been collected by the Geological Survey 

in the base of the Kellaways Rock of Wilts., and therefore did not indicate 

a Macrocephalitan date. 3 In view of the occurrence of typical shales of the 

jason zone immediately above, it seems certain that the Kellaways Rock is a 

direct continuation of that in Lincolnshire and other parts of England. 

The outcrop is concealed beneath the Chalk for a distance of over 13 miles, 

from between North Newbald and Sancton to north of Kirby Underdale. 

The disappearance is proved by the occurrence of derived Kellaways ammonites 

in the base of the Cretaceous to be due to overstep by the Red Chalk. 

Blake described a section of Red Chalk at Great Givendale with 'here and 

there nodules full of [Sigaloceras] calloviense and [Proplanulites] koenigi, some 

of which have been broken up and rolled about in the Red Chalk sea, till their 

crevices are filled with the latter matrix'. 4 

The importance of the Market Weighton Axis during Callovian and 

Oxfordian times is attested by a number of facts. Not only does the Oxford 

Clay attenuate towards it from the south and the north, but in all the Yorkshire 

Basin north of the axis the facies of the Oxford Clay differs markedly, 

both lithologically and palaeontologically, from the development over the 

rest of England. As far as the axis the shales of the jason zone are the same 

from the Dorset coast, while there is reason to suppose that at least the 

majority of the succeeding zones also are normally developed. North of the 

axis only the uppermost part (corresponding roughly with the prcecordatum 

zone) is a clay, and even that is usually to be likened more to a sandy shale 

than to the familiar clay of Southern England. All the rest of the zones, or 

such of them as are present, have become thin ferruginous sandstones or 

oolitic sandy limestones of varying lithology, often crowded with fossils. 

Many of the ammonite species are peculiar to Yorkshire and some show 

affinities with Russian forms. 

1 T. Sheppard, 1900, Geol. Mag. [4], vol. vii, pp. 535-8; and see The Naturalist, 1931, p. 87. 

2 S. S. Buckman, 1922, T.A., vol. iv, p. 54, pi. CCLXXXIII. 

3 1925, T.A., vol. v, p. 73. 

• J. F. Blake, 1878, P.G.A., vol. v, p. 248.


III. THE YORKSHIRE BASIN 

(a) The Inland Escarpments of the Howardian, Hambleton and 

Tabular Hills 1 

No modern palaeontological work has been carried out on the Oxford Clay 

and Kellaways Beds of the inland escarpments of the Yorkshire Basin; the 

most recent account available is that written by Fox-Strangways in his Memoir 

on the Jurassic Rocks of Yorkshire (1892). Until research on modern lines is 

undertaken, the equivalence of the inland rocks with those on the coast must 

remain in doubt, and it is safest to continue to use the old terms 'Oxford Clay' 

and 'Kellaways Rock', although researches on the coast have shown that these 

names have quite different meanings there from those attaching to them in 

the rest of England. It is with this proviso that they are now used, their probable 

zonal equivalence being discussed in a later subsection. 

The formation first appears from beneath the Red Chalk at Garrowby, and 

both the clay and the rock below are traceable from the first, forming a small 

feature along the foot of the Wolds. The Oxford Clay is not more than 20 ft. 

thick, and the 'Kellaways Rock' probably from 15 ft. (or less) to 30 ft. 

The Oxford Clay thickens to 70 ft. in the neighbourhood of the Derwent, 

but seems to diminish again beneath the Howardian Hills. The outcrop along 

these hills can be traced sporadically by a band of wet ground, but there are 

no good sections, and the thickness therefore cannot be satisfactorily estimated. 

The Kellaways Rock in the Howardians is a more important feature: it 

consists of soft sandstone with harder, more siliceous lenticles, which weather 

out of the surrounding sands, giving rise to prominent headlands or nabs. 

A short distance north of the Coxwold faults, the Oxford Clay seems to 

disappear entirely. Intraformational erosion may have removed some of it, 

but it is certain that a considerable portion passes into sandstones indistinguishable 

from the Lower Calcareous Grit. Immediately north of the faults, 

about Wass and Ampleforth, the clay is still normally developed, though 

probably not half its thickness at the Derwent; a few miles away, in the clifflike 

scarp of Roulston Scar, 2 sandstones with ammonites at least as early as 

athleta date, 3 and with a basal pebble-bed, rest directly on the Kellaways 

Rock. The 'Kellaways Rock' is here a peculiar, ferruginous reddish variety, 

crowded with Gryphcea bilobata and belemnites, and may be of any age from 

Proplanulitan to Upper Kosmoceratan, such as that on the coast undoubtedly 

is (see below). 

Along the foot of the great inland cliff of the Hambleton Hills, at least as far 

as Kepwick, the outcrop is much obscured by landslips and talus. At the 

north-west end, below Black Hambleton, and in the small outlier on Osmotherley 

Moor, natural exposures become somewhat clearer, showing that 

the Oxford Clay returns again for a time and is about 50 ft. thick. The thickness 

of the 'Kellaways Rock' here is 60-70 ft., and it has become a thickbedded 

massive sandstone, partly siliceous, partly soft, with a ferruginous 

band towards the top, as on the coast. 

Eastward across Yorkshire to the sea the outcrop follows the edge of the 

1 Based on C. Fox-Strangways, 1892,J.R.B., pp. 283-99. Seemap, fig. 27, p. 138, above. 

2 P. F. Kendall, 1915, Proc. Yorks. Geol. Soc., N.S., vol. xix, pp. 284-5. 

3 Kosmoceras rowlstonense (Young and Bird), figured by Buckman, 1923, T.A., pi. CDXXXVII

OXFORD CLAY: YORKSHIRE BASIN 361 

Tabular Hills, where sections are principally to be seen in the sides of becks. 

Although the general direction of the outcrop along the Tabular Hills is 

W.-E., it is repeatedly cut back in a zigzag fashion, the characteristic feature 

of the formation being a series of nabs formed by the Kellaways Rock. 

In the west, as in the western escarpment at Roulston Scar, although the 

total thickness of Oxford Clay and Kellaways Rock thickens to about as much 

as in the east (120-50 ft.), the proportion of sandstone is much greater— 

more than 100 ft. This is again due to the lower portion of the Oxford Clay 

passing into sandstone, which is often separated from the rest of the rock 

below by a thin clay-band. 

In the almost complete absence of palaeontological evidence little can be 

said as to the zonal significance of these changes. Hudleston visualized the 

whole of the Middle Oolites as deposited around a shore lying to the northwest, 

from which the materials were derived (largely from the Millstone Grit? 

But see p. 581). The nearer the deposits lay to the shore, the higher would be 

the proportion of arenaceous material, and he believed that over the Vale of York, 

before the retreat of the escarpment, there might have been seen a continuous 

succession of sands and sandstones from the Estuarine Series to the Coral Rag. 

Tow r ards the east end of the Tabular Hills, on the Hackness outlier and on 

the coast, the major portion of the 120 to 150 ft. consists of clay, but both its 

upward and its downward boundaries are indefinite—Fox-Strangways wrote: 

'The junction of the upper portion of the Oxford Clay with the base of the 

Calcareous Grit is so gradual that no exact line can be drawn/ Certainly 

on the coast the base of the Grit falls within the prcecordatum zone. 1 

The best sections anywhere inland are afforded by the precipitous gorges 

of Newton Dale and its tributaries, which cut deep into the heathy plateau 

formed by the Kellaways Rock. Miles of more or less vertical cliffs expose 

up to 90 ft. of sandstones comparable with some of the Kellaways Rock of the 

rest of the county, above which are from 30 ft. to 50 ft. of the softer sandstones 

representing the lower part of the Yorkshire Oxford Clay (probably about 

athleta date). At the base of all are'10-15 ft- & re Y shales full of small 

crushed lamellibranchs, especially a species of Pseudomonotis. 

(b) The North Yorkshire Outliers 

North of the valley of the Esk a syncline striking E.-W. through Whitby 

has given rise to the preservation of a large elongated outlier, or rather series 

of outliers, of the Kellaways Rock from 8 to 12 miles from the main outcrop, 

forming Roxby and Danby High Moors, Moorsholme Moor and neighbouring 

heights. The sandstones on these outliers are close-grained and well bedded, 

with seams of quartz pebbles. The most interesting part is the upper, which 

is hard and siliceous, and is riddled with the hollow casts of belemnites, the 

guards completely dissolved away. 

'Sometimes as many as 50 of these casts occur in a cubic foot of the bed, and 

blocks of from three to six inches thick will have a dozen cylindrical perforations 

right through them. This clearly proves that the Kellaways Rock ... at some depth 

below the surface must be a calcareous sandstone, its extremely porous nature being 

in part due to the dissolution of lime/ 2 

1 Judging by ammonites in the gritstone matrix in the Leckenby collection. 

2 C. Fox-Strangways, 1892, J.R.B., pp. 284-5.


(c) The Yorkshire Coast 

The Oxford Clay and Kellaways Beds are well exposed at intervals in the 

cliffs from Gristhorpe Bay to Scarborough. The longest section is in Gristhorpe 

Bay, where the Oxford Clay forms the greater part of Gristhorpe Cliff, 

but both it and the Kellaways Beds are much obscured by slips, talus and 

Drift. The whole series is magnificently displayed in Red Cliff, Cayton Bay, 

but as the cliff is vertical and very high the rocks are scarcely accessible. There 

is a more accessible but less clear exposure of Oxford Clay on the north side 

of Cayton Bay, where the Kellaways Rock is faulted down below beach-level. 

The rock and the shale beneath extend on to Wheatcroft Cliff, and the whole 

series is again brought dow T n by faults at North Cliff, Scarborough, and in the 

Castle Hill (fig. 76, p. 430). 

The thickness of the Oxford Clay in Gristhorpe and Cayton Bays is 

about 120 to 150 ft. It is a grey sandy shale, nearly uniform throughout, and 

it passes upwards gradually into the Lower Calcareous Grit; fossils are everywhere 

scarce except in the bottom layers at Scarborough. According to 

Hudleston a thick mass of sandstone like the Lower Calcareous Grit comes 

in in the lower part of the clay in the north side of Cayton Bay, but the cliff 

has since become obscured by landslips. It would, however, be only in 

accordance with expectations, for a similar change certainly occurs inland 

when the clay is traced towards the north. 

The few ammonites that have been collected from the Oxford Clay have 

been discussed briefly by Buckman, 1 whose conclusions seem to point to the 

greater part of the clay belonging approximately to the prcecordatum zone. 

At least two species, Klematosphinctes vernoni (Young and Bird) 2 and Neumayriceras 

oculatum (Phil.) 3 , are peculiar to Yorkshire and so afford no help in 

correlation. Buckman provisionally spoke of the vernoni zone, but this had 

only local value and his subsequent attempt 4 to fit it into sequence with other 

hemerae was little more than guesswork. Dr. Spath has since concluded that 

it is a synonym of the prcecordatum zone. 5 

The so-called Kellaways Rock, where it first rises from the beach at Newbiggin 

Wyke, at the south end of Gristhorpe Bay, is only 12 ft. thick. It 

thickens steadily northward, reaching about 50 ft. in Cayton Bay and 76 ft. 

in North Cliff, Scarborough. Two essentially different parts can be made out: 

an upper portion (in the south about half the rock, in the north 25 ft.) crowded 

with fossils embedded in a variety of matrices, some grey, some blue, some 

red, often oolitic, but usually more or less ferruginous; and a lower portion 

consisting of thick beds of almost barren sandstone. The upper portion 

yielded a wealth of fossils to the Scarborough collector of the middle of last 

century, John Leckenby, most of whose collections are now in the Sedgwick 

Museum, Cambridge. 6 They were nearly all obtained from boulders on the 

beach at the foot of Scarborough Castle Hill, from temporary excavations for 

buildings on the North Cliff, and from the cliffs and beach in Gristhorpe Bay. 

Unfortunately the Scarborough locality was long ago covered up by the 

1 S. S. Buckman, 1913, Q.J.G.S., vol. Ixix, p. 159. 

2 T.A., 1922, pi. cccxxxin. 

4 T.A., vol. v, 1925, p. 72. 

5 L. F. Spath, 1926, The Naturalist, p. 324. 

6 J. Leckenby, 1859, Q.J.G.Svol. xv, pp. 4-15. 

3 T.A., 1921, pi. ccxxiv.

OXFORD CLAY: YORKSHIRE COAST 363 

extension of the marine parade round the foot of the hill, while the outcrop 

in Gristhorpe Cliff has been for many years badly obscured by landslips. 

From the numerous ammonites collected by Leckenby and his contemporaries, 

it is evident that the term Kellaways Rock is a misnomer, and it was 

to distinguish the Yorkshire rock from that south of the Humber that the 

mis-spelling Kelloway Rock was formerly retained, an expedient tending only 

to add to the confusion. Dr. Spath has recently suggested as alternatives 

HACKNESS ROCK (a term introduced by William Smith as early as 1829-30, 

which it is appropriate to his memory to revive) 1 or Castle Hill Beds. 

Oppel first pointed out that Phillips's 'Kelloway Rock' in Yorkshire contained 

fossils indicative of the athleta zone, which was called Oxford Clay 

elsewhere; and he used the fact as an argument for including the Lower 

Oxford Clay in the Callovian Stage. 2 In 1875, also, Hudleston wrote: 3 

\ . .of the petrological group known as the Kelloway Rock, the Upper, or Cephalopoda 

division, seems to contain ammonites belonging to two geological divisions, 

of which A. modiolaris (Lhuid) and A. gozverianus (Sow.) represent callovian forms, 

whilst A. duncani (Sow.), A. jason Reinecke (A. gulielmi Sow.), A. lamberti (Sow.), 

and many others, are characteristic of the Oraflfws-clays, or Lower Oxfordian' . .. 4 in 

order to prevent mistakes arising from names it is necessary to point out that the 

fauna of the upper part of the Kelloway Rock of Yorkshiie, as indicated by its 

ammonites, embraces much of the Oxfordian of English geologists.' 

Hudleston also realized that, like so many ferruginous deposits full of 

Cephalopods, these beds were slowly-formed accumulations representing 

thick strata elsewhere, and probably of very different ages in different places. 

'Are the fossiliferous (Cephalopoda) beds in the upper part of the Kelloway Rock 

at Scarborough, at Red Cliff, and at Gristhorpe, wholly contemporaneous deposits ? 

At Scarborough the ornati seem to be very plentiful; at Red Cliff, A. gowerianus, 

&c.; at Gristhorpe the cordati, as A. vertumnus Leek. (A. marice d'Orb.), and A. 

flexicostatus Phil. (A. lamberti Sow.), &c. This question can only be settled by a very 

close attention to the precise position of specimens collected during a considerable 

lapse of time.' And again: "The deposition of the upper portions alone extended 

over a period sufficiently long to intercept and entomb amongst other remains the 

ammonites of two horizons which seem to have been distinguished in other districts.' 4 

Unfortunately the prolonged and careful field investigation advocated by 

Hudleston has been rendered almost impossible for the reasons just mentioned. 

In 1913 Buckman published the results of an examination of many 

of Leckenby's, Young and Bird's and Phillips's types and attempted to 

arrange the ammonites in sequence according to their matrices, identifying 

the matrices so far as possible with the beds in Cayton Bay, as described by 

Leckenby and by Fox-Strangways. 5 The sources of error in such an arm-chair 

method are so great as to render the results of little practical value. In the 

first place, the ammonites examined came chiefly from Scarborough and 

Gristhorpe, at which places, as pointed out by Hudleston, the faunas and 

matrices are both very different. An attempt to recognize these in the 

1 'Memoir on the Stratification of the Hackness Hills', 1829-30, printed in J.R.B., vol. i, 

1892, pp. 507-14. 

2 A. Oppel, 1856-8, Die Jurafor motion, pp. 538-44. 

3 W. H. Hudleston, 1875, P.G.A., vol. iv, p. 372. 

4 Ibid. 

5 S. S. Buckman, 1913, Q.J.G.S., vol. lxix, pp. 152-68.


inaccessible Red Cliff at Cayton Bay, and that only secondhand from 

descriptions, was unlikely to prove a profitable task. Nevertheless, the results 

obtained have a theoretical interest and are suggestive of possibilities open 

to local geologists who might be able to devote a long time to the task. 

According to Fox-Strangways, 1 the uppermost 19 ft. at Red Cliff, Cayton 

Bay, consists at the west end of one indivisible mass of brownish-red ferruginous 

rock, which passes eastward into several locally distinct bands. At 

the top towards the east may be distinguished a very oolitic, hard band, 1 ft. 

thick, which stands out from the cliff, and overlies 9 ft. of calcareous shale like 

Oxford Clay. From this clay or its representative at Scarborough were 

doubtless collected many of the anomalous ammonites recorded from the base 

of the Oxford Clay of that locality. The hard band or its equivalent were 

thought by Fox-Strangways and by Buckman to be the same as a fossiliferous 

band spoken of by Leckenby as the 'calcareous pisolite'. With this Buckman 

identified the matrix of A. gregarium Bean-Leckenby, 2 A. turgidum Bean, and 

the associated fauna, and he named it the gregarium zone. The shale below, 

which at Osgodby Nab is described as oolitic, Buckman identified as the 

provenance of Vertumniceras vertumnus (Bean-Leckenby) and Quenstedtoceras 

lamberti (Sow.) with an associated fauna. Finally, the old records of 

Ammonites crenatus he took to indicate the possible representation of the zone 

of Creniceras renggeri. Thus he divided this topmost 10 ft. of the Hackness 

Rock into the zones of gregarium, vertumnus and lamberti in descending order, 

and suspected the presence of a representative of the renggeri zone in unknown 

relation to the rest. Since Q. gregarium and V. vertumnus are peculiar to 

Yorkshire and have never been collected in situ it is not known whether they 

attained their acmes separately, or contemporaneously with Q. lamberti. For 

present purposes it is safe to assume only, as does Dr. Spath, that these 10 ft. of 

beds were probably deposited in the hemerae lamberti and renggeri (or marice). 

Next below come ferruginous beds to a maximum thickness (at Red Cliff) 

of 9 ft. Fox-Strangways describes these as comprising 3 ft. of soft sandstone 

overlying 6 ft. of red, irony, partly oolitic rock full of Gryphaeas; Leckenby 

divides them into three, a bed of soft sandstone sandwiched between two 

fossiliferous irony bands. In various matrices identified with these beds 

Buckman records a number of ammonites, including Peltoceras athleta, 

Kosmoceras duncani, and a number of Kosmocerates typical of the basal shales 

of the Oxford Clay farther south (thz jason zone). 

Perhaps the most peculiar feature of the sequence is the record of Ammonites 

koenigi by Leckenby in both of his irony bands, and also his records 

of A. sublcevisy A. gowerianus and A. chamusseti in the lower. Buckman 

identified in the collections the true Proplanulites koenigi, and also several 

species of Cadoceras and tw T o species of Sigaloceras, all in a light-brown 

calcareous matrix with small ooliths. These he believed to have come from 

Leckenby's lower irony bed. 

Thus at Red Cliff between the fauna of the koenigi zone and the Cornbrash 

there are about 35 ft. of strata, which become still thicker towards the north. 

At the base are shales formerly associated with the Cornbrash (6-15 ft.) 

which pass up gradually through yellow sandy shale into sandstone. All the 

1 1892, J.H.B., p. 280. 

2 Made genotype of Prorsiceras Buckman, 1918, T.A.y vol. ii, pi. cxvn.

OXFORD CLAY: EASTERN SCOTLAND 365 

rest of the rock consists of almost barren sandstone with occasional plantremains. 

Near the base at Scarborough, however, Hudleston described 

a shelly bed containing Trigonia rupellensis, Pseudomonotis sp., Pholadomya 

murchisoni and other bivalves. 

Since no ammonites have yet been found in these basal sandstones and 

shales they must be for the present regarded as part of a greatly-expanded 

koenigi zone, and so equivalent to the Kellaways Clay and possibly also to the 

lower part of the true Kellaways Rock of Wiltshire. The presence of a calloviense 

zone is doubtful, for although species of Sigaloceras have been found, 

they have not been proved to occupy any separate stratum of rock, being 

apparently mixed with the fauna of the koenigi zone. 

Thus the greater part of the so-called Kellaways Rock of the Yorkshire 

coast is still apparently a true representative of at least the lower part of the 

Kellaways Beds of the rest of England. The name Hackness Rock should 

therefore be restricted to the highly fossiliferous topmost part, containing the 

fauna of the Lower and Middle Oxford Clay, and for this hitherto unnamed 

but important series of beds it is a valuable addition to stratigraphical nomenclature. 

IV. EAST SCOTLAND 

(a) The Brora District of Sutherland 

In East Sutherland rocks of the age of the Oxford Clay and Kellaways Beds 

cover an area about 3 miles square and attain a thickness of 350-400 ft. 

(fig. 63, p. 366). They occupy the central and widest part of the narrow 

coastal strip of Jurassic strata about Brora, bounded inland by the great Ord 

Fault, which throws them down against the Old Red Sandstone mountains. 

The softer Jurassic rocks form a low coastal plain, largely obscured by 

glacial debris and raised beaches. 

The coast-sections are at first sight disappointing. Such cliffs as exist are 

nearly all cut in raised beach material or in blown sand, while the Jurassic 

substratum protrudes only as reefs and ledges, overgrown with seaweed and 

covered at high tide. 

The Oxford Clay is more favourably exposed for study than the other 

formations, however, owing to the River Brora having cut a steep-sided valley 

across the outcrop. Natural and artificial sections along the valley yield 

considerably more information than those on the shore. In the village of 

Brora the valley becomes a gorge, whose cliff-like sides are composed of 

sandstones equivalent to the upper part of the Oxford Clay. Higher upstream, 

behind Fascally Coal Mine, a large clay-pit has been excavated for 

the exploitation of the Lower Oxford Clay for a brickworks near by. 

The deposits are divisible into three well-marked lithic groups. The 

highest 200 ft. (approximately) consist of sandstone with sandy shale at the 

base, united under the term BRORA ARENACEOUS SERIES ; they correspond to 

the Upper Oxford Clay (prcecordatum, lamberti and athleta zones) and to an 

unknown extent also to the Lower Calcareous Grit. Below is a series of 

argillaceous shales and clays, the BRORA ARGILLACEOUS SERIES, which is from 

150 to 225 ft. thick, and spans the Lower Oxford Clay (duncani to jason 

zones). At the base of all is a hard band of rock forming the Roof-Bed of the 

Brora Coal and yielding the fauna of the Kellaways Clay (koenigi zone). 

R54371 C C

FIG. 63. Sketch-map of the Jurassic area around Brora, Sutherland, 

showing the position of Fascally Coal Mine, Clynelish Quarry, Uppat 

Quarry, &c. (Based on the i-inch map of the Geological Survey of Scotland, 

Sheet 103.) 

Wide hatching = Brora Argillaceous Series; close hatching = Brora 

Arenaceous Series. Blown sand dotted; alluvium thus: V ; raised beach 

material thus: UJ. (See fig. 28, p. 151.)

OXFORD CLAY: EASTERN SCOTLAND 367 

SUMMARY OF THE SEQUENCE AT BRORA 1 

Praecordatum Zone (? and Cordatum Zone pars) (BRORA SANDSTONE), 

c. 120 ft. 

The thick sandstones which form the cliffs of the gorge below the bridges 

in Brora were estimated by Lee to have a thickness of about 100 ft. 2 Unfortunately 

they have not in recent times yielded any fossils, and they therefore 

cannot be exactly dated. The upper portions probably correspond 

largely with the lower part of the English Lower Calcareous Grit, and the 

lower portions with the upper subzone of the prcecordatum zone. A definite 

Lower Calcareous Grit fauna is found above and an ammonite assemblage 

dated as prcecordatum a short distance below. 

Three-quarters of a mile north-west of Brora Railway Station the Brora 

Sandstone rises into one of the highest eminences on the coastal plain, the low 

rounded Braambury Hill, immediately south of the hamlet of Clynelish. Old 

quarries scar the south side of the hill, the highest showing 20 ft. of unfossiliferous 

white sandstone, a lower one showing another 15 ft. of sandstone, 

chiefly white, with pebbles of quartz and nests of Limas and Pectens. At the 

top of the lower quarry is a 6 ft. band crowded with casts of Pseudomonotis 

braamburiensis (Phil.). 3 The rock is in places a spongy mass of the casts, but 

they are poorly preserved and good specimens are not easily obtained. 

Praecordatum Zone (pars) (CLYNELISH QUARRY SANDSTONE), C. 20 ft. 

Farther south, down the hill-side towards the River Brora, | mile northwest 

of Fascally Coal Mine, a large excavation called Clynelish Quarry is still 

worked, and yields a rich fauna. The sandstone is white and fine-grained, and, 

though originally soft, it is silicified to a depth of 10 ft. from the surface in 

such a way as to resemble a fine quartzite, and it is much used for building. 

The softer lower portion contains abundant casts and moulds of fossils, of 

which by far the commonest are lamellibranchs of typical Lower Corallian 

species. The most abundant are Chlamys fibrosa, ChL splendens, Lima rigida, 

L. mutabilis, Lucina sp., Exogyra nana and Gryphcea dilatata var. exaltata. 

Besides these there are a few species not known elsewhere, such as Trigonia 

joassi Lycett, and a brachiopod figured by Davidson as Terebratula bisuffarcinata 

Schloth., but probably a new species. The ammonites are of uncertain 

date, for scarcely any of them have been found elsewhere; Buckman considered 

them to be of late Vertumnicertan age, equivalent to what is here 

grouped in the prcecordatum zone. The commonest is Aspidoceras silphouense 

(Y. & B.), which may be found in fair abundance as casts. Of rarer occurrence 

are casts of Sutherlandiceras sutherlandice (Sow.), 4 S. albisaxeum S. Buck., 5 

Cardioceras cf. cardia S. Buck, and Quenstedtoceras cf. macrum (Quenst.). 

Lamberti and Athleta Zones (FASCALLY SANDSTONE, C. 20 ft., and FASCALLY 

SHALE, 50 ft.). 

The beds below the Clynelish Quarry Sandstone are exposed in the banks 

1 Based on G. W. Lee, 1925, 'Geol. Golspie', Mem. Geol. Surv., and observations. 

2 Judd, owing to certain errors, gave an estimate of 400 ft. But see Lee, 1925, loc. cit., p. 86. 

3 The name, derived from this hill, was first used by Sowerby, but as a nomen nudum, a 

Yorkshire specimen being later figured by Phillips and becoming ipso facto the type. 

4 T.A.y pi. CCCLXIV. 5 T.A.y pi. cccxx.


of the River Brora east of Fascally Coal Mine (PL XIV). The cliffs which there 

rise sheer from the water show about 15 ft. of brown, grey and rusty FASCALLY 

SANDSTONE, in which ochreous impressions of Lucina lyrata Phil, and L. 

discoidalis Buv. abound. The Survey obtained from the cliffs on the sides of 

the river a number of specimens of Quenstedtoceras, w T hich Buckman compared 

to Q. lamberti, 0. prcelamberti, and four other species. With them were found 

some Kosmocerates. A correlation was thus established with the Tidmoor 

Point Beds. No sign of the renggeri zone has been found. 

At the base of the sandstones is a row of doggers, from which have been 

obtained fragmentary Kosmoceratids. The late Dr. Lee and Buckman did 

not name them, but Dr. Pringle considers them to indicate the horizon of 

K. pronicey l which is here considered to be part of the athleta zone (see table, 

p. 340). 

The row of doggers divides the sandstones from about 50 ft. of efflorescent 

sandy shales, lithologically intermediate between the Brora Arenaceous and 

the Brora Argillaceous Series. Only the highest part (5 ft. or more) is visible 

on the banks of the river, in the side of the road leading down to Fascally Coal 

Mine, and this highest part Buckman originally included in the Fascally 

Sandstone. It seems advisable, however, to keep it separate, under the name 

of FASCALLY SHALE ; on the foreshore, where the full thickness can be seen, 

Dr. Lee obtained a measurement of 50 ft. 

From the upper part of the Fascally Shale the Survey collected three species 

of Peltoceras, indicative of the athleta zone. 

Jason-Duncani Zones (BRORA BRICK CLAYS AND BRORA SHALES). 

Below the Fascally Shale are at least 200 ft. (225 ft. measured by Lee on 

the shore) of clays and shales representing the lower part of the Oxford Clay. 

The entire succession crops out south of the Brora estuary, where it forms 

muddy platforms accessible at low tide. This is not, however, a favourable 

locality for studying the fauna, and the best exposures are again to be found 

on the north bank of the Brora River, near Fascally. 

The highest clays, which may be distinguished as the BRORA BRICK CLAYS, 2 

are dug in a large open brick-pit immediately above Fascally Coal Mine. The 

only common fossils are Cylindroteuthis puzosi and Gryphcea cf. lituola, but 

the Survey have recorded Kosmoceras cf. jason (Rein.), K. cf. stutchburii 

(Pratt) and K. sedgwickii? (Pratt), the first two of which Buckman figured as 

K. zugium S. B. (genotype of Zugokosmoceras) and K. interpositum S. B. Brinkmann 

has since declared both to be synonymous with K. grossouvrei Douv. 3 

Beneath the brick clay is a thick series of shaly clays, little of which is 

exposed except on the foreshore; they are distinguished by the Survey as the 

BRORA SHALES. From the shore platforms the Survey have collected numerous 

Kosmoceratids, to which nearly all the current names have been applied: 

duncani, elizabethce, castory jason, stutchburii, sedgwickii, &c. Until very careful 

revision of the Kosmocerates collected at Brora has been undertaken, in the 

light of modern w r ork, the most that can safely be said about these beds is that 

1 J. Pringle, 1930, P.G.A., vol. xli, p. 74. 

2 Buckman referred to the Brick Clay as the 'Fascally Shales (Brickyard Beds)' (T.A., 1923, 

vol. iv, p. 41), a misnomer, since of all parts of the series this deposit most deserves to be 

classed as a clay. The Survey use the term Brora Clays (G. W. Lee, 1925, loc. cit., p. 81). 

3 T.A., pis. CCCLXXXIX and CDXIX; Brinkmann, 1929, loc. cit., p. 50.

OXFORD CLAY: BRORA ROOF BED 369 

the whole of the Brora Argillaceous Series corresponds in general with the 

Lower Oxford Clay (jason-duncani zones). 1 

Kcenigi Zone (KELLAWAYS BEDS), 3-5 ft. (+ ?). 

Judd recorded Ammonites calloviense from Brora, but modern collecting has 

failed to confirm his record, and it seems probable that the calloviense zone 

is wanting. 

The koenigi zone, or stratal equivalent of the Kellaways Clay, forms the 

ROOF BED of the Brora Coal and is one of the best-known fossiliferous beds 

of the district. It is a very hard, ferruginous, sandy limestone, weathering red, 

from 3 ft. to 5 ft. thick, and passing down into grey calcareous sandstone with 

lenticles of coal. In the early days of the coal-mining at Brora large quantities 

of the Roof Bed were broken up and brought to the surface, so that fossils 

could easily be collected. Several were figured in Sowerby's Mineral Conchology 

and so became types of familiar species; notably Gowericeras gowerianum, 

Pholadomya murchisoniy P. acuticostata, Protocardia striatula and Anatina 

undulata. 

Nowadays it is difficult to study the Roof Bed. The only exposure, except 

in the working mine, is in the form of a ledge exposed at low tide on the foreshore 

half a mile south of Brora. The stone is much overgrown with seaweed 

and barnacles, and is very untractable with the hammer. 

The ammonite fauna, comprising Gowericeras 2 and two species of Proplanulites, 

leaves no doubt as to the correspondence of the Roof Bed with the 

Kellaways Clay. 

(b) Ross-shire 3 

Twenty miles south of Brora, in the diminutive patch of Jurassic rocks 

beside the Moray Firth, on the coast of the peninsula which separates the 

Dornoch from the Cromarty Firth, two shore-sections of Oxfordian beds 

have been studied by Judd and more lately by Lee. They are situated at 

Port-an-Righ, miles south of Balintore (Shandwick), and consist of reefs 

visible only at low tide. The best exposure stretches along the beach northeast 

from the Fishermen's hut, while the other, less complete but more comprehensive, 

lies at Cadh'-an-Righ, a few hundred yards farther south. Both 

are near the boundary fault, which throws the Oxfordian strata against the 

Old Red Sandstone at a high angle. 

The more northerly section displays 50 ft. of shaly beds containing the 

fauna of the prcecordatum zone at top and bottom, and passing up into 

Corallian Beds. The more southerly exposure also shows part of the prcecordatum 

zone, and in addition 14 ft. of shales belonging to the lamberti zone, and, 

after a considerable gap, another 14 ft. of clay and shale of the jason zone, 

resting directly upon the Brora Roof Bed. 

The chief interest of the sections lies in the shaly development of the 

prcecordatum and lamberti zones, which present a marked contrast with the 

sandstones of the Brora Arenaceous Series only 20 miles to the north. Here 

1 Buckman in 1923, without sufficient knowledge of the conditions under which the strata 

occur, constructed a hypothetical sequence, introducing several unfortunate stratal terms, not 

adopted by the Survey and better dropped. T.A., 1923, vol. iv, p. 41, and see explanatory 

note at top of p. 40. 

2 See T.A.y pis. CCLXXXVII* and CDIV. 

3 G. W. Lee, 1925, loc. cit., pp. 99-101, 85-6.


the beds are almost entirely shales, for the most part grey and soft, but occasionally 

harder and calcareous, forming a shaly-weathering limestone. The 

Survey have collected a rich fauna of Cardiocerates, belonging to species 

characteristic of both the upper and the lower subzones of the prcecordatum 

zone at Horton-cum-Studley, Oxfordshire; among them are C. cardia, C. 

prcecordatum, and C. cf. tenuicostatum. Associated with them are a few 

lamellibranchs, such as Gryphcea dilatata, Pinna lanceolata and other familiar 

species. 

From the shales of the lamberti zone in the southerly section they obtained 

Q. lamberti and several other species; and from the basal layers of the Lower 

Oxford Clay an assemblage of the usual Kosmocerates. The absence of the 

calloviense fauna here corroborates the negative evidence obtained in Sutherland. 

The Brora Roof Bed, 1-2 ft. thick, is represented by tough calcareous 

shelly sandstone, weathering olive green, and having at the top a band of 

ironstone nodules and abundant belemnites. No ammonites were found in it. 

V. THE HEBRIDEAN AREA 1 

The extension of the Oxfordian sea over the Hebridean area is proved by 

relics of typical Oxford Clay, and in two places of Kellaways Beds, in the 

three islands of Skye, Eigg, and Scalpa. There is reason to believe that the 

formation underlies the basalts of a large part of the northern end of Trotternish 

in the north of Skye, for it crops out from underneath the volcanic 

covering on both sides of the peninsula and round the north end, around 

Loch Staffin in the east and also on the west coast at Duntulm, Mugsted or 

Monkstadt and Uig. It was first described at Staffin by E. Forbes in 1851, and 

in 1878 Judd discovered 'the same beds, with precisely similar characters and 

fossils' cropping out at low water in Laig Bay, on the island of Eigg. In the 

present century the Survey have discovered a considerable outcrop around 

the edge of the basalts of the Strathaird peninsula in the south of Skye, and 

also small faulted remnants at Strollamus, Skye, and on the adjoining coast 

of Scalpa. 

A remarkable feature of these occurrences is the differences in the zonal 

position of the lowest members of the Oxfordian formation, resting upon the 

Great Estuarine Series, in the different places. In Strathaird and Eigg the 

whole of the formation, with the exception of a localized thin development of 

the Kellaways Beds, consists of Cardioceratan deposits of prcecordatum date, 

grading up into cordatum deposits referable to the Lower Calcareous Grit. 

In Trotternish in the north, however, the sequence appears to have been 

more fully developed, and Kosmoceratan and Proplanulitan faunas intervene 

between the Cardioceratan deposits and the Great Estuarine Series. 

In Trotternish the formation consists of blue clays and shales with subordinate 

bands of argillaceous limestone and septarian nodules. The only 

passable section is on the foreshore in Staffin Bay, for a description of which 

I am indebted to Mr. Malcolm MacGregor, M.Sc., whose important researches 

in Northern Trotternish it is hoped will soon be published. He 

1 Based on C. B. Wedd, 1910, 'Geol. Glenelg, Lochalsh and S.E. Skye', pp. 128-31; G. 

Barrow, 1908, in 'Geol. Small Isles of Inverness-shire', pp. 26-8; G. W. Lee, 1925, in Tre- 

Tert. Geol. Mull, Loch Aline and Oban', pp. 113-14, Mems. Geol. Surv.

OXFORD CLAY: HEBRIDES 371 

informs me that the section (which is the one mentioned by Forbes), although 

the lower beds can only be consulted at low water during spring tides, shows 

about 100 ft. of dark shales with some thin bands of concretionary limestone. 

In the basal 20 ft. of the shale, which rests with a 1 ft. pebble bed on the sands 

and sandstones of the Great Estuarine Series, he found Quenstedtoceras 

lamberti and Vertumniceras vertumnus. About 20 ft. from the base is a double 

band of concretionary limestone, above which he found abundant Cardiocerates 

of very various styles, prcecordatum, cordatum, vertebrale and excavatum 

types being apparently represented; also Peltoceratoides, 'Belemnites 

oweni\ Gryphcea dilatata, Nucula, &c. 1 

A specimen collected by the Survey and named by Buckman Kosmoceras 

degradatum 2 would seem to indicate the presence of Kosmoceratan deposits 

also at Staffin. 

On the west side of the peninsula, at Uig, Bryce and Tate in 1873 collected 

A. lamberti and A.jasonf with 'Belemnites owenV in dark shales and clays; and 

near by, at Monkstadt (Mugstok) Murchison as early as 1829 had recorded 

A. koenigi. 3 

In 1925 the Survey reported the discovery of a tiny faulted patch of 

Oxfordian strata in Mull, in the right bank of a stream which flows into 

Duart Bay, at a point 300 yards above the bridge. The rock is a marly, 

fine-grained sandstone, containing a fossil-bed, from which were collected 

ammonites identified by Buckman as Kosmoceras elizabethce-spoliatumQuenst 

Reineckeia spp. and Phlycticeras sp. I have seen the material (of which there 

is a considerable quantity) and, as Dr. Spath points out, the supposed 

Kosmocerates have keels and are undoubtedly Amceboceras kitchini Salf., 

while the 'Reineckeias* are nothing else than Rasenice. Reineckeia therefore 

still remains undiscovered in Northern England or Scotland (see below, p. 478). 

The small faulted fragments overlying the Estuarine Series at Strollamus 

and Scalpa are much metamorphosed and have yielded no new information. 

They appear to be Cardioceratan in date. 

The occurrences in Strathaird and in Eigg are important and the study of 

them in recent years by the Survey has added greatly to our knowledge of the 

Scottish Oxford Clay. 

In Strathaird the Oxfordian beds occur over a large part of the promontory, 

cropping out from below the basalt in the western cliffs, north of Elgol. Here 

they may reach a thickness of as much as 300 ft.,of which an unknown portion 

near the top should be assigned to the Lower Calcareous Grit; northwards 

they are overstepped by the basalt. Lithologically the beds are more sandy 

than in the north of Skye. The upper portion still consists of dark grey or 

blue micaceous shale, probably altered from a clay, but downwards it becomes 

1 Buckman figured from Staffin Peltoceratoides torosus (Oppel), T.A., pi. DLXIII, and the 

genotype and holotype of Korythoceras korys, pi. CCCLXI. 

2 T.A., pi. CDXXXVII. 

3 R. I. Murchison, 1829, Trans. Geol. Soc. [2], vol. ii, p. 311. Bryce (1873, Q.J.G.S., vol. 

xxix, p. 332) misquotes Murchison as recording 'A. koenigi in masses . . The passage 

actually reads: *I . . . found several fossils in blue shale through which a deep canal has 

recently been cut by Lord Macdonald, to drain the lake of Mugsted. Among the shells are 

the ammonites konigi, ostreae in masses, many belemnites, flattened tellinse? &c.' Jones 

showed that the ' Pflattened tellinae' were the Ostracod, Estheria murchisoni Forbes, of the 

Great Estuarine Series, and the masses of Ostrece also indicate that the Ostrea hebridica Beds 

of the Great Estuarine Series were cut through.


more sandy until, in about the lowest 80 ft., it has become a succession of 

shaly, micaceous or calcareous sandstones and grits. The basement beds are 

coarse-grained and pebbly, in places forming a striking-looking conglomerate 

of white quartz and quartzite pebbles, often more than an inch in diameter. 

From the base upwards the sandstones yield an unmistakable Upper Oxford 

Clay fauna, with (according to the specific identifications of 1910) distinct 

Low r er Calcareous Grit elements. Wedd records Cardioceras cordatum, C. 

? nikitinianum, C. cf. rotundatum, C. rouilleri, C. sues si, C. tenuicostatum, C. cf. 

vertebrate, Chlamys fibrosa and Pseudomonotis cf. ovalis as making their appearance 

near the base of the formation. There is here no indication of any other 

part of the Oxford Clay but prcecordatum and cordatum beds. 

Apparently similar conditions would appear, from Barrow's account, to 

obtain in Eigg, except that there the sandstones are much thinner. The 

exposures are limited to shore-reefs between tide-marks in Laig Bay, and 

to a little gorge east of Laig Farm. The upper part of the sequence, exposed 

on the shore, consists of dark grey shales, like those at Loch Staffin but more 

friable than those of Strathaird. They have yielded fossils identified as 

Cardioceras cordatum (2 forms, coarsely and finely ribbed), C. excavatum, 

Aspidoceras perarmatum and a number of Corallian lamellibranchs, and there 

can be no doubt that they should be referred to the Lower Calcareous Grit 

(cordatum zone) at least in part, as in Strathaird. Underneath, in the gully 

near Laig Farm, is a bed of limestone about 8 ft. thick, beneath which are 

about 12 ft. of calcareous sandstone, neither yielding diagnostic fossils, the 

latter resting on the Great Estuarine Series. 

The presence of Kellaways Beds in at least one locality in Strathaird is 

proved by large fallen blocks of sandstone lying on the beach, north of Elgol. 

They contain nests of a small Callovian Rhynchonelloideay cf. socialis, together 

with Ornithella kellawaysensisy Pseudomonotis sp., and occasional ammonites 

assigned to Gowericeras gowerianumy marking the koenigi zone. The bed from 

which the blocks fell has not been identified in situy and it is not known 

whether its position is above or below the basal conglomerate. 

The relations of the Oxford Clay to the underlying rocks in the Hebrides 

are shown by these few remaining relics to be far more non-sequential and 

irregular than anywhere in England. The isolated patch of Cornbrash in 

Raasay, the equally isolated occurrences of Kellaways Beds at Elgol and 

Monkstadt, the restricted area of Lower Oxford Clay in north-east Trotternish, 

and the overlapping of late prcecordatum deposits on to the Great 

Estuarine Series in Eigg and in parts of Strathaird, testify to greater disturbances 

than were experienced at the period in any other parts of the British 

Isles. 

VI. KENT 1 

The concealed outcrop of the Oxford Clay beneath the Cretaceous rocks 

under Kent forms a strip from 1 to 3 miles wide, running parallel to the thin 

Lower Oolites and dipping south with them. Beginning at the coast on the 

south side of St. Margaret's Bay, it underlies Canterbury, Faversham and 

Sittingbourne, and passes close to the north of Gillingham and Gravesend. 

1 Based on Lamplugh and Kitchin, 1911, loc. cit.; and Lamplugh, Kitchin and Pringle, 

1923, loc. cit.

OXFORD CLAY: KENT 373 

On this belt and to the south of it the Oxford Clay and Kellaways Beds have 

been pierced in several borings. The bulk of the Oxford Clay consists of 

uniform blue-grey clay, of fine texture, with subordinate brown bands, while 

the prcecordatum zone is altogether peculiar, consisting of ironshot marls such 

as are developed on the other side of the Channel. The Kellaways Beds, as 

usual, proved exceedingly variable. 

The Oxford Clay thickens rapidly westward from about 130 ft. at Dover to 

200-210 ft. at Brabourne and Chilham, near the line of the railway south-west 

of Canterbury. 1 The Kellaways Beds also thicken from the coast towards 

Canterbury and thin out again farther west. The maximum thickness recorded 

is 43 ft. at Fredville, almost midway between Canterbury and Dover, while 

farther west, at Brabourne and Harmansole, less than 20 ft. was proved. 

Praecordatum Zone. 

SUMMARY OF THE OXFORD CLAY IN KENT 

At the top of the formation, in and just above the ironshot marls, a rich 

fauna of Cardiocerates was found. The highest of these were still of prcecordatum 

date and, as no palaeontological proof of the cordatum zone or Lower 

Calcareous Grit was found, the prcecordatum zone is probably directly overlain 

by the martelli beds, as at Quainton. The zone is, however, very differently 

developed from the typical clays familiar in other parts of England, consisting 

largely of marls and marlstones full of brown ironshot ooliths, such as are 

found on the same horizon in the cliffs between Villers and Houlgate in 

Normandy. For this reason the Survey classed them in their Memoirs as 

Lower Corallian. 

The highest bed in which Cardiocerates were found was a band of hard 

grey marlstone, about 4 ft. thick, crowded with black-coated fossils. The 

stratum was recognized at Fredville, Snowdown Colliery, Bere Farm, Brabourne, 

Chilton, Chilham, and probably also at Guildford. Its ammonites 

were recorded as Cardioceras cf. excavatum (Sow.), C. cf. pingue (Rouill.) and 

undescribed species, two of which were compared with C. cordatum Lahusen 

(non Sow.) and C. cordatum de Loriol (non Sow.); Aspidoceras sp., resembling 

A.faustum Bayle; Peltoceras arduennense (d'Orb.) in abundance, P. cf. eugenii 

(d'Orb.); Perisphinctes bernensis de Lor. (pars.), P. cf. variocostatus (Buckland) 

and P. sp. nov. The commonest lamellibranchs were Isognomon cf. 

cordati (Uhlig) and Unicardium sulcatum Leckenby, with which were associated 

such more typically Corallian species as Chlamys fibrosa, C. incequicostata 

(Phil.), Camptonectes lens (Sow.), and the brachiopods Terebratula farcinata 

Douv. and Rhynchonelloidea thurmanni (Voltz.). This mixed fauna and the 

abundance of the fossils point to the bed being a product of slow deposition, 

perhaps spanning parts of the prcecordatum and cordatum zones. 

A few feet beneath this interesting bed was an almost equally persistent 

band of marly, crumbly, locally pisolitic clay, which also yielded a number of 

fossils of Corallian facies—Nucleolites dimidiatus (Phil.), N. scutatus Lam., 

Holectypus cf. oblongus Wright, a large Gryphcea, numerous valves of Chlamys 

fibrosa, and fragments of a large Perisphinctes cf. variocostatus. Were it not 

1 These figures include the ironshot marls of the prcecordatum zone, which the Survey 

classed with their Lower Corallian.


for the Cardiocerates in the marlstone above it, one would certainly group 

this bed with the Corallian. 

Below are 25-35 ft. of olive green and brown marlstones and marls, more 

or less filled with ironshot grains and on the whole richly fossiliferous. 

Cardiocerates were again most conspicuous, including C. cordatum Lah. 

(non Sow.), C. excavatum Lah. (non Sow.), C. rouillierihdh., C. tenuicostatum 

(Nik.) and undescribed species. Near the base were found C. nikitinianum 

Lah., Aspidoceras oegir? (Oppel) and (T)Peltomorphites williamsoni (Phil.). 

Gryphcece were not numerous, but such as were found were of the large, 

massive varieties of G. dilatata so characteristic of the prcecordatum zone 

inland. Among the most interesting of the fossils were fragments of the stems 

of Millericrinus, suggestive of the Marnes a Millericrinus on the same horizon 

in the Boulonnais. 

It is perhaps noteworthy that, although no ironshot oolite occurs in the 

prcecordatum zone in Dorset, yet the presence of a quantity of iron in the zone 

is attested by the red coatings of the nodules in the Red Nodule Beds. 

Renggeri and Lamberti Zones. 

Beneath the prcecordatum zone numerous Quenstedtocerates were found, 

as usual in the form of pyritized casts, and among them Q. lamberti (Sow.), 

Q. leachi (Sow.), Q. macrum (Quenst.) and Q. goliathum (d'Orb.) were 

identified. With these were some species of the genus Crenicerasy indicating 

the renggeri zone, and indeed the name Renggeri Beds was originally applied 

to this middle division. The lamellibranch fauna provided interesting evidence 

for the connexion with the Bernese Jura, suggested by the Perisphinctids 

in the overlying zone, and bearing out Prof. Davies's remarks on the fauna 

from this zone collected at Ludgershall railway-cutting, Bucks. Parallelodon 

(Grammatodon) concinnum (Phil.), P. (G.) montanayensis, Lima cf. trembiazensis, 

NucMana roederi, Perisphinctes cf. billodensis, all species described by de 

Loriol from the Bernese Jura, were identified. As in other parts of the 

country and on the Continent, two typical Middle Oxford Clay fossils 

occurred, the Decapod Crustacean, Mecocheirus socialis (Meyer), and the 

subequilateral and well coiled Gryphceay G. lituola Lamk. 

Duncani-Jason Zones. 

The Lower or Kosmoceratan Oxford Clay is condensed and much of it is 

full of bivalves, especially Astarte, Nucula and Cucullcea, thus showing that 

the conditions of deposition were not of the anaerobic type normal at the time 

in most other parts of England. Probably, too, sedimentation was much 

interrupted by penecontemporaneous erosion. No evidence of the athleta 

zone was found, but the numerous specimens of Kosmoceras in the usual 

pyritized or crushed condition, and some of Erymnoceras, gave evidence of 

duncaniy reginaldi and jason horizons, in descending order. At Fredville and 

Chilham specimens of Erymnoceras occurred a few feet from the base. 

Calloviense and Koenigi Zones (KELLAWAYS BEDS). 

The Kellaways Rock is sharply demarcated, both lithologically and 

palaeontologically, from the overlying clays, having always a fauna and certain 

lithic characters entirely its own. It is more sandy than the Oxford Clay and

OXFORD CLAY: KENT 375 

usually ferruginous, and throughout it Gryphcea bilobata and allied species 

are abundant. The Gryphaeas become larger towards the top, those in the 

lower part being very diminutive, like the small form so common at Kellaways. 

Other common species, also recalling the fauna at Kellaways and in 

Yorkshire, are Oxytoma sp., Pseudomonotis sp., Pleuromya recurva and Ento- 

Hum demissum. The ammonites show that the bulk of the rock belongs to the 

calloviense zone. No examples of Gowericeras or Sigaloceras were found, 

while only one imperfect fragment of an ammonite resembling a Proplanulites 

was obtained, in the basal bed at Oxney. This is all the palaeontological 

evidence for the koenigi zone, but there is between the Kellaways Rock and 

the Cornbrash a bed of clay a few feet thick which may represent the Kellaways 

Clay. It w r as classed by Messrs. Lamplugh, Kitchin and Pringle with 

the Cornbrash, but they likened it to the wrongly-styled 'Clays of the Cornbrash' 

in Yorkshire, which we have seen are more properly classed with the 

Kellaways Clay.

Zones (Plate XXXVIII). 

Ringsteadia 

anglica1 anglica1 anglica1 anglica1 and 

Perisphinctes 

(Dichotomosphinctes) 

wartce 2 wartce 2 wartce 2 wartce 2 

Perisphinctes 

{Dichotomosphinctes) 

antecedens3 antecedens3 antecedens3 antecedens3 antecedens3 and 

Perisphinctes 

martelli4 and 

Perisphinctes 

martelli4 and 

Perisphinctes 

martelli 

Cardioceras 

cordatum 5 

CHAPTER XIII 

CORALLIAN BEDS 

Stratal 

Divisions. Dorset Strata. 

Ringstead Coral Bed 

Upper 

Calcareous 

Ringstead Waxy Clay 

Grit Sandsfoot Grit 

Glos 

Oolite 

Series6 Series6 Osmington 

Oolite 

Series 

4 Berkshire 

Oolite 

Series 

Lower 

Calcareous 

Grit 

Sandsfoot Clay 

Trigonia clavellata Beds 

Osmington 

Oolite 

Series 

Bencliff Grit 

Nothe Clay 

Trigonia hudlestoni Bed 

Nothe Grit 

1 Salfeld's zone of Ringsteadia anglica Salf. and R. pseudocordata (Bl. & Hudl.), including 

his rather doubtful zone of Perisphinctes decipiens (Sow.), a species which has not yet been 

properly determined. P. decipiens (Sow.) has been recorded in the Sandsfoot Grit, but a 

separate zone for this is unnecessary, as it contains Ringsteadia from base to summit. As 

alternative zonal indices to P. decipiens, Salfeld used P. achilles d'Orb., a foreign species not 

yet found in this country and [Prionodoceras] serratum (Sow.) (the former in his two zonal 

tables, 1914, AT. Jarb.fur Min., BB., vol. xxxvii, and the latter in the text, loc. cit., p. 129). 

P. serratum, however, seems to range up to the very top of the Ringsteadia zone and possibly 

also into the zone of Pictonia baylei at the base of the Kimeridge Clay (as at Swindon, Salfeld, 

loc. cit., p. 196); Buckman considered the genus Kimeridgian. 

2 The ammonites (and other fauna) of the Sandsfoot Clay are very little known. Salfeld 

placed it in his zone of P. wartce and [Amoeboceras] alternans von Buch; but the only 

specimens truly assignable to P. wartce that I have seen from England are one in the Geological 

Survey collection from the Westbury Iron Ore (No. 25484) and some collected by Prof. 

Davies from the Ampthill Clay (see p. 410). 

3 Forms identical with Perisphinctes antecedens Salf. are found in the Osmington Oolite Series 

inland, and this series is stratigraphically so distinct from the Berkshire Oolites that it was 

formerly for the sake of convenience considered to be a separate zone. It is probable, however, 

that it is only a subdivision of the broad martelli zone, for there are two specimens of P. cf. 

martelli in the British Museum from some part of the Osmington Oolite Series near Weymouth. 

P. antecedens occurs in the Trigonia clavellata Beds. 

4 The Berkshire Oolite Series had not been differentiated at the time when Salfeld evolved 

his zonal scheme; it is the chief repository of the martelli or transversarius fauna. The index 

fossil is very rare, but allied species abound; Schindewolf coined for them a new generic 

name, Martelliceras, which Dr. Spath declares precisely synonymous with Perisphinctes sensu 

stricto (1931, Pal. Indica, NS., vol. ix, p. 401). 

5 Aspidoceras perarmatum (Sow.) is sometimes made alternative zonal index; but it is only 

known from Yorkshire, where it is very rare. A. catena (Sow.) is better. 

6 From Glos, near Lisieux, Normandy, where the Glos Sands link up the T. clavellata 

Beds (Gres d'Hennequeville) with the Sandsfoot Clay (Argile noire); see Arkell, 1930, 

P.G.A.y vol. xli, p. 399.

CORALLIAN BEDS: DORSET COAST 377 

I. DORSET 

(a) The Northern Limb of the Weymouth Anticline: Ringstead to 

Abbotsbury 

THE Corallian Beds crop out along both limbs of the Weymouth Anticline, 

dipping away to north and south beneath the Kimeridge Clay. 

The northern outcrop, 13 miles in length and seldom more than \ mile 

wide, is marked by a ridge of downs running from the coast at Ringstead and 

Osmington to the Chesil Bank west of Abbotsbury. The ridge rises westward 

to a maximum height of 316 ft. above the sea at Linton Hill, near Abbotsbury, 

and near the end it is crowned by the ancient chapel of St. Catherine; southward 

lie the Oxford Clay lowlands and to the north the deep valley of the 

Kimeridge Clay (map, p. 342). 

At the west end of the outcrop there are no natural sections exposed by the 

sea, owing to the protective action of the Chesil Bank, but the east end provides 

the finest exposures of Corallian rocks in Britain. The entire succession 

may be measured and studied in detail, through a total thickness of rather 

more than 200 ft., extending, with several repetitions, along some three miles 

of cliffs (fig. 64). 

In Ringstead Bay in the east, the beds first appear gradually from beneath 

the Kimeridge Clay in low banks, rising into cliffs as the harder middle 

portions of the formation are brought up above sea-level. For a considerable 

distance a steep precipice is formed of the Osmington Oolite Series, capped 

by the Trigonia Beds, dipping gently to the east (PI. XVI). At the foot is the 

Bencliff Grit. At Osmington Mills some complicated faulting interrupts the 

succession, and the Nothe Clay and much of the Lower Calcareous Grit are 

obscured. 

From Osmington Mills westward the Corallian Beds are tilted steeply to 

the north, and the hard bands of the Osmington Oolite Series run in parallel 

ridges along the beach, standing nearly on edge. At Shortlake Chine they 

rise in the cliff and a complete section is provided down to the Oxford Clay, 

but the Lower Calcareous Grit here is somewhat obscured by vegetation. 

Towards Redcliff Point an anticlinal flexure brings down the Lower Calcareous 

Grit almost to sea-level once more, and there are magnificent exposures 

of this division and of the Nothe Clay on both sides of the Point. 1 

At Bowleaze Cove at the west end of Redcliff the base of the Lower Calcareous 

Grit passes finally out of the cliffs, which thence turn southward and expose 

only Oxford Clay under Jordan Hill (fig. 65, p. 382). 

The succession here and south of Weymouth was systematically described 

during the last century by Blake and Hudleston2 and again, with amendments, 

by H. B. Woodward. 3 In 1926 I re-measured and described all the 

exposures and during recent years have collected fossils carefully, bed by 

bed. 4 

1 The Point itself consists of a small upthrown block of Oxford Clay, largely obscured by 

slips. 

2 J. F. Blake and W. H. Hudleston, 1877, Q.J.G.S., vol. xxxiii, pp. 260-75. 


4 A brief correlation was published in 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, pp. 156-9.

OSMINGTON 

MILLS 

NOTH£(lO.CALC.)GR»T n othe CLAY cmr 

SHORTLAKE BLACK HEAD 

bran point 

RINGSTEAD BAY 

( W. END) 

FIG. 64. Sections of the Corallian Beds in the cliffs west of Osmington (above) and east of Osmington (below). Length of each 11 miles. THE two 

sections are separated by a £ mile of cliffs in which the Corallian Beds dip almost vertically and the strike coincides with the line of the coast. The 

upper section is continuous with the lower one in fig. 65. (Outline based on Strahan, 1898, 'Geol. Isle of Purbeck and Weymouth , Mem. Geol. Surv.y 

Plate ix.) Vertical scale exaggerated.


SUMMARY OF THE CORALLIAN SERIES, RINGSTEAD TO OSMINGTON 1 

Upper Calcareous Grit, 18-20 ft. 

The stratum taken to be the topmost bed of the Corallian is the RINGSTEAD 

CORAL BED, known as the Kimeridge Grit by Damon and as the Upper Coral 

Rag by Blake and Hudleston and by Woodward. It rises gradually from the 

beach in the western side of Ringstead Bay and, though it appears to have 

been often obscured in the past by slipped Kimeridge Clay and gravel, it has 

been well exposed in recent years (PI. XXI). It consists of 8 in. of tough, 

green, argillaceous limestone, largely made up of shells and broken corals. 

The commonest fossils are the large Ctenostreon proboscideum (Sow.), with 

which are associated Chlamys splendens (Dollf.), C. nattheimensis (de Lor.), 

Camptonectes lens (Sow.), Entolium demissum (Phil.), Velata hautcoeuri (Dollf.), 

Lima rigida (Sow.), Myoconcha texta (Buv.), Ostrea delta Smith, and a number 

of other lamellibranchs and gastropods, with spines of Cidaris florigemma and 

the corals Thecosmilia annularis, Thamnastrcea concinna, &c. 

In a westerly direction, towards Osmington, the fossils become scarcer. 

Where the bed reappears beyond Osmington, under Black Head, the only 

species at all abundant is Ctenostreon proboscideum. The rock becomes at the 

same time less tough and is shot with ferruginous ooliths, while farther still, 

on the Weymouth promontory to the south, it passes into a true ironshot 

oolite and all fossils are comparatively rare. From this it may be deduced that 

the coral reef, to which the coral fragments and shells at Ringstead bear 

witness, lay under the Chalk Downs to the east. 

Beneath the Ringstead Coral Bed are the RINGSTEAD WAXY CLAYS, 10 ft. 

of waxy, ferruginous clay, interrupted by seams of claystone nodules towards 

the top, and numerous seams of laminated claystone or clay-ironstone 

throughout, with layers of Ostrea delta towards the base. Immediately subjacent 

to the Coral Bed is a 3-in. band of especially prominent, red clayironstone 

nodules, containing occasional specimens of Ringsteadia anglica Salf. 

These beds may be correlated approximately with the Westbury Iron Ore 

of Wiltshire. Recognizable ammonites do not seem to have been obtainable 

in recent years from the Ringstead Coral Bed itself, 2 but undoubted fragments 

of Pictonia are common in the clay immediately above, while Ringsteadia is 

found immediately below. 

The SANDFOOT GRIT, some 25 ft. thick at Sandsfoot Castle, south of 

Weymouth, measures only about 7 ft. at Ringstead Bay. Where it rises from 

the beach beneath the Ringstead Waxy Clays, at the west end of the bay, it 

consists only of a 2-ft. band of bright red sandstone, speckled with white 

ooliths and quartz grains, and containing fucoid markings, overlying 5 ft. of 

brown sandy marls. Farther west, at Black Head, Osmington, the single hard 

band has thickened to 4 ft. and has split up into four bands of red and green 

ferruginous sandstone, with the same speckling of ooliths and quartz grains. 

The commonest fossils are Chlamys midas (d'Orb.), Goniomya, Pleuromya, 

and Nautilus hexagonus (Sow.). Blake and Hudleston recorded 4 Ammonites 

decipiens\ and at Sandsfoot Ringsteadice are not uncommon. 

1 Based mainly on unpublished manuscript. 

2 Damon recorded a dozen species, but most of them, if correctly identified, certainly came 

from beds above and below. (Geol. Weymouth, 2nd ed., 18S4, pp. 65-6.)


Glos Oolite Series, 50 ft. 

The SANDSFOOT CLAY, probably about 20 ft. thick at Ringstead 1 and about 

30 ft. thick at Black Head, consists of grey, blue and brown clay with varying 

amounts of ferruginous staining and greenish sand. Layers of Ostrea delta 

are abundant near the top and are liberally distributed throughout, the shells 

being indistinguishable from those in the basal portion of the Kimeridge Clay, 

except that on an average they died before attaining such an advanced stage of 

growth. 

At the west end of the outcrop, near Abbotsbury, the thickness is much 

diminished. The deposit is therefore somewhat lenticular. 

The TRIGONIA CLAVELLATA Beds, 14^ ft. These beds are the most remarkable 

in the whole Corallian Series, for they are veritable fossilized shellbanks. 

They consist of strong courses of tough red and purplish-brown shelly 

limestone (the Red Beds of Damon) separated by marly partings, the whole 

crowded with bivalves and other fossils. On some of the slabs valves of 

Trigonia clavellata are massed so closely together that they touch and form 

a continuous pavement; on other slabs Pectens, oysters, Astartes, &c. predominate. 

As a source of well-preserved fossils these beds were early renowned, 

and Sowerby figured several of the species in The Mineral Conchology: 

namely Trigonia clavellata, Gervillia aviculoides, Mytilus pectinatus and 

Lopha solitaria. Besides these, type-specimens of species founded by subsequent 

investigators have come from the same beds—those of the abundant 

Plicatula weymouthiana Damon, Pteria pteropernoides (Blake and Hudleston) 

and Chlamys super fibrosa Arkell. Other abundant species are Cucullcea contracta 

Phil., Pteroperna polyodon (Buv.) and Cerithium muricatum Sow. Small 

pieces of coral occur and, very rarely, Perisphinctids. All these seem to 

belong to the narrow-whorled group of which P. wartce Bukowski is a 

member,but they resemble Salfeld's 'mut' antecedens of North-West Germany 

rather than the type-form from Poland, which has a marked forward sweep 

of the secondary ribs on the periphery (see Plate XXXVIII). 2 

Osmington Oolite Series, 63-5 ft. 

Blake and Hudleston drew the boundary between the T. clavellata Beds and 

the Osmington Oolite Series far below the occurrence of the Trigonia. There 

is a gradual lithological passage between the two divisions, but it is essential 

to be guided by the palaeontology and, following H. B. Woodward, to restrict 

the name T. clavellata Beds to the beds actually containing this fauna. 3 Below 

comes a highly variable series of strata, for the most part comparatively 

barren of fossils. They form the cliffs to the east of Osmington, where they 

are magnificently exposed and can be studied in detail. Of the total thickness 

of 63-5 ft. between Ringstead and Osmington in the east, only 6 ft. 3 in. consist 

of the typical white oolite, such as is used for building. 

The true Osmington Oolite is a solid, white, even-grained, oolitic freestone, 

with some clay-galls and vertical tubiform markings. It occurs in two blocks, 

1 H. B. Woodward (1895, J.R.B.t p. 85) states 10-12 ft., but this seems to be an underestimate. 

The thickness is difficult to determine owing to slips. 

2 There are a few specimens in the British Museum, collected by Damon, and a fragmentary 

example in my own collection, none of them the true wartce. 

3 H. B. Woodward, 1895, J.R.B., pp. 85, 86, 91.

PLATE XVII 


Osmington Oolite Series, east of Osmington Mills, Dorset. 

SC = Sandsfoot Clay capping cliff; TCB = Trigonia clavellata Beds; OF = 

Oolite facies and LCF = Littlemore Clay facies of Osmington Oolite Series; 

BG = Bencliff Grit. 


Osmington Oolite Series, Bran Point, east of Osmington Mills, Dorset. 

The lowest ledge is of gritty oolite and rests directly on the Bencliff Grit; next 

above it is (Q) the Chlamys qualicosta Bed, and (P) the pisolite seam. The 

strong bands near the top of the cliff towards the point are Trigonia clavellata 

Beds, and the capping is Sandsfoot Clay.

PLATE XVII 


RedclifF, near Weymouth. 

LCG = Lower Calcareous Grit; THB = Trigonia hudlestoni Bed; NC = 

Nothe Clay. A crest of Osmington Oolite is seen behind and above the slope 

of Nothe Clay and Bencliff Grit (which is mostly concealed). 


Redcliff, near Weymouth. 

The large blocks on the right have fallen from the Trigonia hudlestoni Bed.


2 ft. and 4 ft. 3 in. thick. Most of the rest of the sequence consists of blue and 

grey oolitic or pisolitic marly clays with bands of nodular, grey, argillaceous 

limestone. From its occurrence in Littlemore railway-cutting, near Oxford, 

this facies is known as the Littlemore Clay Beds. At the top are over 20 ft. of 

conspicuously nodular, concretionary, partly oolitic grey and white limestones; 

this facies too is typically represented in the Midlands, especially about 

Oxford, where it is known as the Nodular Coralline Rubble. 

Near the base is a 1 \ ft. band of hard, shelly, oolitic and pisolitic, gritty 

limestone, crowded with Chlamys qualicosta (Etall.), C. fibrosa (Sow.), and 

Exogyra nana (Sow.), and above it, separated by 2 ft. of clay, is a seam of loose 

pisolite. The pisolite (2 ft.) is a very persistent feature, marking the base of 

the Osmington Oolite Series throughout Dorset and as far as South Wiltshire. 

Westward, along the strike, the solid white oolite-facies increases in importance; 

west of Osmington the 2-ft. seam divides into two, the 4-ft. seam 

doubles in thickness, and a third seam (4 ft. thick) appears below the others. 

At the top of Redcliff the white oolite division takes on a facies closely resembling 

Forest Marble: false-bedding is intensified, much of the oolite grows 

sandy and fissile, and it is full of clay-galls. In the face of the cliff, 6 ft. out 

of the total thickness of 13 ft. pass in a short distance into sandy, shaly, 

greenish clay, with thin films of fissile limestone. This facies is only local, for 

in a quarry on the top of Jordan Hill, \ mile to the west, the division is a solid 

false-bedded oolite once more. 

At the west end of the outcrop, about Abbotsbury, a high proportion of the 

Osmington Oolite Series has passed into hard white oolite, which has been 

extensively quarried. A thickness of 22 ft. may be seen in a single quarryface; 

but fossils are very scarce. 

Palaeontologically the Osmington Oolite Series yields little information. 

It may be said to be characterized principally by the admixture of ChlamysK 

fibrosa and Chlamys qualicosta. The former seldom, if ever, ranges above it, 

and the latter has not been found below it. Ammonites are extremely rare, 

but in the British Museum (Damon Collection) there are two large specimens 

of Perisphinctes martelli Oppel, labelled as from the Osmington Oolite of 

Osmington, and in a matrix that seems to bear out the labels. Inland, about 

Oxford, the commonest of the rare ammonites in these beds belong to the 

group of P. antecedens Salfeld; but associated with them are other forms of 

Perisphinctes sensu strictoy which are certainly very closely allied to P. martelli 

—itself a rare species in this country. 

Berkshire Oolite Series, 55-60 ft. 

The BENCLIFF GRIT (called after Bencliff or Bincleave at Weymouth) is 

about 14 ft. thick east of Osmington and only about 10 ft. thick farther west, 

at Shortlake. It consists of yellow and white sands, locally false-bedded, with 

a few doggers and seams o£interlaminated clay, and at the bottom a band of 

huge doggers of gritstone; these measure over 6 ft. in diameter, and are composed 

of intensely hard, blue, false-bedded, indurated calcareous grit, with 

occasional Gryphcea dilatata and Serpuke. They are a conspicuous feature 

on the beach wherever the grits crop out in the cliff—even when, as at Redcliff, 

the outcrop is completely hidden by slipped ground. 

The NOTHE CLAY (from Nothe Point, Weymouth) is 35-40 ft. thick. East

NEAR W/KE SANDSFOOT BINCLEAVE TORPEDO GARDENS THE 

REGIS HALT CASTLE (BENCLIFF) WORKS NOTHE 

OVERCOMBE JORDAN BOWLEAZE REDCLIFF REDCLIFF 

CLIFF POINT 

FIG. 65. Sections of the Corallian Beds in the cliffs south of Weymouth (above): distance slightly less than 2. miles (based on H. B. Woodward, 

1895, J.R.B., p. 83); and north of Weymouth (below): distance I-I miles (outline based on Strahan, 1898, 'Geol. Isle of Purbeck and Weymouth*, 

Mem. Geol. Surv., Plate ix). Vertical scale exaggerated.


and west of Osmington the Bencliff Grit is the lowest bed clearly exposed in 

ordered sequence, and to study the downward continuation it is necessary to 

pass westward to Shortlake and Redcliff. At Redcliff the Nothe Clay forms 

tumbled and slipped ground in the upper part of the cliff on both sides of the 

Point. About 38-40 ft. may be measured. It consists principally of grey-blue 

shaly clay, with two thin bands (8-10 in.) of dark-brown ferruginous limestone 

in the lower part, containing fucoid markings and fossils—Chlamys 

fibrosa, Lima subantiquata Roem., Gervillia aviculoides, Modiola bipartita, 

Gryphcea dilatata, Pholadomya and Pleuromya. There are also several bands 

of nodules or nodular limestone. 

The PRESTON GRIT or TRIGONIA HUDLESTONI BED (from Preston village, 

near Redcliff) is 5-6 ft. thick. Blake and Hudleston and other observers included 

this bed in the Nothe [= Lower Calcareous] Grit, but as it is one of 

the most fossiliferous beds in the Dorset Corallian, and one of the most 

valuable for purposes of correlation, it is important to keep it separate, either 

under Buckman's name, Preston Grit, 1 or as the Trigonia hudlestoni Bed. 2 It 

is a massive band of hard, brownish-grey, gritty, speckled, doubtfully oolitic 

limestone, full of fucoid markings, which forms a prominent feature west of 

the point (PI. XVII). The huge fallen cubes on the foreshore provide good 

opportunities for collecting, and they have yielded all the essential fauna of 

the Trigonia hudlestoni Beds of the inland Berkshire Oolite Series: Perisphinctes 

helence De Riaz, Cardioceras excavatum (Sow.), Cardioceras cf. vertebrale 

(Sow.), Aspidoceras sp., Goliathiceras sp., Trigonia hudlestoni Lyc., 

Camptonectes lens, Chlamys fibrosa, Chlamys splendens, Cucullcea contracta, 

Lima rigida, L. subantiquata, Ostrea quadr angular is, Lopha gregarea, Gryphcea 

dilatata, Oxytoma expansa, Pseudomonotis ovalis, &c. 3 

Lower Calcareous Grit, 27 ft. 

Blake and Hudleston called the Lower Calcareous Grit the Nothe Grit, 

after the Nothe promontory, Weymouth, but this term may be suppressed as 

a synonym. At Redcliff the whole thickness is conveniently exposed on both 

sides of the Point. It consists of yellow and grey sands,soft,bluish, argillaceous 

sand, and somewhat shaly and sandy marl, with several beds of doggers or 

more or less constant bands of gritstone. Towards the west, as pointed out 

by Blake and Hudleston, the grits and sands die out and pass laterally into 

clay 'till at Broadwey, due north of Weymouth, they are scarcely discoverable, 

unless represented by a single 2-ft. block of ferruginous sandstone, lying in 

the midst of clays; and only a thin band can be identified in the valley south 

of Abbotsbury, which is excavated down to the Oxford Clay 5 . 4 

The only abundant fossils in the Lower Calcareous Grit are large specimens 

of Gryphcea dilatata. Most of the fossils recorded by authors undoubtedly 

came from the Trigonia hudlestoni Bed. Even Buckman, as late as 1925, 

seems to have fallen into the error of identifying fossils in blocks of grit on 

the shore, broken from the T. hudlestoni Bed, and recording them as from the 

Lower Calcareous Grit. 5 


2 W. J. Arkell, 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, p. 158. 


4 Blake and Hudleston, 1877, loc. cit., p. 264. 

5 S. S. Buckman, 1925, T.A., vol. v, p. 65, bed 7.


Buckman named three subdivisions of the beds at Redcliff, in descending 

order, Radcliff Grit, Jordan Grit, and Ham Cliff Grit. 1 But the misidentifications 

just mentioned vitiate his palaeontological distinctions, while his failure 

to publish measurements makes it difficult to obtain even an approximate idea 

of what he intended to include under the three terms. The ephemeral nature 

of the minor lithological units, as demonstrated by their westerly passage into 

clay, renders any subdivisional terms of doubtful value. 

At a level 4 ft. below the base of the Trigonia hudlestoni Bed (as well as in it) 

I have obtained several specimens of Cardioceras cf. excavatum, in situ in the 

cliff west of Redcliff Point, near Bowleaze Cove. A short distance lower begin 

curious bands of large nodules of intensely hard, dark-grey, argillaceous 

gritstone, some of which resemble cannon-balls protruding from the larger 

doggers or grit-bands. Buckman noticed the highest and most conspicuous 

layer of these nodules (in his Jordan Grit) and said that they were 'obviously 

derived', perhaps from the Patellate Layer in the Oxford Clay. 2 Closer inspection, 

however, makes it certain that they are not derived, but are of 

concretionary origin. They occur at several levels in the Lower Calcareous 

Grit, the lowest layer being only 5 ft. from the base, and both the nodules and 

the surrounding grits sometimes contain the same large Gryphaeas. Identical 

concretions are a conspicuous feature of the Lower Calcareous Grit in Yorkshire, 

where they are especially well seen at Cayton Bay. 

(b) The Southern Limb of the Weymouth Anticline: Weymouth 

The southern outcrop, though only 2i miles in greatest length, is classic 

ground. The area is triangular, with the base of the triangle running E.-W. 

from the Nothe to the East Fleet Backwater and the apex near Small Mouth, 

where the road and the railway to Portland leave the mainland, crossing the 

mouth of the Fleet to Chesil Bank. On it are built the southern part of the 

town of Weymouth, with the upland parishes of Rodwell and Wyke Regis, 

and along its eastern coast are the type-sections at the Nothe Point, Bincleave 

or Bencliff, and Sandsfoot. 

The deterioration of these sections has been so great during the present 

century that it is no longer possible to study the complete succession. The 

building of the breakwaters enclosing Portland Harbour has arrested coast 

erosion, and the cliffs of Sandsfoot Clay have now nearly reached stability, 

overgrown with thickets and trees; the construction of the torpedo works at 

Bincleave has closed the exposure of the Osmington Oolite Series to the public, 

and since the making of the road leading to the works the type-section of the 

Bencliff Grit has become totally obscured. The fortification of the Nothe 

long ago destroyed the type-section of the Nothe Grits, while that of the 

Nothe Clay received its coup de grdce in 1931 by the laying out of the cliff as 

gardens. Finally, a supplementary section of the Osmington Oolites and 

Trigonia clavellata Beds in Rodwell railway-cutting, described by Blake and 

Hudleston, is completely overgrown. 

Only the Sandsfoot Grits can still be clearly seen, forming the striking red 

cliffs below the perched ruin of Sandsfoot Castle. Even of these the uppermost 

beds are obscured, but a continuous exposure can be seen in the low 

banks of the Fleet, south of Wyke Regis. The locality affords an interesting 

1 1925, loc. cit., p. 65. 2 J 925, loc. cit., p. 65.


comparison with the northern limb of the Weymouth Anticline, for, although 

according to measurements published by H. B. Woodward in 1895 the total 

thickness of the Corallian Beds is 196 ft., or 7 ft. less than at Osmington, the 

Upper Calcareous Grit has expanded to 40 ft. Of this the highest 16 ft. 

comprise the Ringstead Waxy Clays with ironstone-nodules, correlated at 

Ringstead and Osmington with the Westbury Iron Ore; and here, in fact, 

a 1-ft. band of typical ironshot oolite like that at Westbury is found at the 

top, occupying the stratigraphical position of the Ringstead Coral Bed. 

The Sandsfoot Grits proper, 24 ft. thick, consist of ferruginous sand and 

sandstone, the harder portions crowded with fossils; and in the upper part is 

a 5-ft. band of clay. The lamellibranch fauna of the grits is exceedingly 

interesting. It comprises only a small number of species, but they have 

a restricted range and constitute a highly characteristic assemblage. The 

most fossiliferous bed is near the base: it is packed with the valves of Chlamys 

midas, Ostrea delta and Pinna sandsfootensis Arkell, with which are associated 

the large Camptonectes sandsfootensis Ark., Modiola, and other forms. The 

ponderous Ctenostreon proboscideum is abundant throughout. 1 Some of the 

bands are a mass of ramifying fucoid markings, like those seen on a smaller 

scale in the Nothe Grits. Blake and Hudleston considered that these denoted 

the actual spot where a colony of algae grew, but although the suggestion is 

probably correct, no organic structure has been found in them. The ammonites 

belong principally to the genus Ringsteadia, and the locality yielded 

a number of the specimens described by Salfeld in his monograph of the genus. 

Since this type-section of the British Upper Calcareous Grit has been 

variously interpreted by Waagen, Blake, Blake and Hudleston, Woodward, 

and Salfeld, so that considerable doubt concerning the succession has crept 

into the literature (largely owing to the obscure language of Blake, who considered 

the uppermost a series of 'Passage Beds'—and what beds are not 

'Passage Beds'?), I append the following record of the section, measured 

along the bank of the Fleet south of Wyke Regis and checked so far as possible 

at Sandsfoot. 

UPPER CALCAREOUS GRIT SOUTH OF WYKE REGIS 

Kimeridge Clay. 

ft. in. 

13. Blue-grey shaly clay, with layers of O. delta; seen to . . . 6 0 

12. Exogyra nana and E. virgula Bed: brown sandy band locally hardened 

like Forest Marble, crowded with small Exogyrce\ as at Ringstead, &c. 

11. Rhactorhynchia inconstans Bed; grey clay, with Rh. inconstans, Exogyra 

prcevirgula Jourdy, and Modiola durnovarice Ark.; Pictonia sp. found 

8 

at Ringstead . . . . . . . . . . 1 8 

Upper Calcareous Grit. 

WESTBURY IRON ORE BEDS (16 ft.) 

10. Prominent band of red clay-ironstone nodules . . . . 3 

9. IRONSHOT OOLITE: dark ferruginous ooliths in a cream-coloured rubbly 

limestone matrix; large Serpulce, Modiola sp., Exogyra nana and 

Ctenostreon proboscideum [= Ringstead Coral Bed] . . . 1 0 

1 It was here that Dean Buckland of Oxford collected the type-specimens figured by 

Sowerby in The Mineral Conchology,


8. RINGSTEAD WAXY CLAY: Brown and red waxy clay, seen to 3 ft., below ft. in. 

which is an unmeasurable gap of perhaps 3-5 ft., and then 6 ft. of 

blue-grey clay with a few clay-ironstone nodules. [Ringsteadia 

anglica Salf. found near the top of this clay in situ at Ringstead.] 

Total of clay according to Blake and Hudleston . . 15 o 

SANDSFOOT GRITS (24 ft.) 

7. Sand, yellow and ferruginous, full of rubble and fucoid markings, with 

Pleuromya and many broken O. delta . . . . . 4 6 

6. Sand, more consolidated, with some prominent hard bands, containing 

Pinna sandsfootensis and full of fucoid markings . . . 3 0 

5. Clay, blue and brown . . . . . . . . 5 0 

passing down into 

4. Sand, impure, ferruginous, with Pleuromya and O. delta and impersistent 

hard grit bands full of fucoid markings. Ringsteadia pseudoyo 

Salf. found in situ at Sandsfoot . . . . . . 8 6 

3. Clay, sandy, passing into sand under Sandsfoot Castle . . . 1 6 

2. Fossil Bed: hard ferruginous gritstone, a mass of Chlamys midas, 

Ctenostreon proboscideum, Ostrea delta, &c. This band is very 

noticeable at the base of the grits at Sandsfoot Castle, where a large 

Ringsteadia was seen in situ . . . . . . . 2 0 

Glos Oolite Series. 

1. SANDSFOOT CLAY, much concealed by slips and vegetation, with 

abundant Ostrea delta at the top. [Total 38-40 ft. at Sandsfoot, according 

to authors]: seen to about . . . . . . 1 2 0 

It is fairly certain that the ironshot oolite (9) is the equivalent of the Ringstead 

Coral Bed, although a prominent band of red clay-ironstone nodules 

occurs above the one and below r the other, for near Osmington the coral bed 

is seen to pass into ironshot oolite westward. 

The line here adopted as the top of the Corallian formation (the top of the 

Ringsteadia zone) agrees with that drawn by Waagen and by Blake and 

Hudleston, but Woodward classed all above Bed 7 with the Kimeridge Clay. 

The whole of the Sandsfoot Beds, including the Sandsfoot Clay, were stated 

by Sedgwick in 1826 to be 'within the limits of the Kimeridge Clay', 1 and this 

truly expresses the affinities of their fauna if the beds are to be parcelled into 

stages, using the terms Kimeridgian or Oxfordian. Waagen's subsequent 

conclusion that the Upper Calcareous Grit belongs w r ith the Oxfordian is not 

upheld by the palaeontology. 2 

The remarks at the beginning of this section show that little remains to be 

said regarding the downward continuation of the sequence. 

The Trigonia clavellata Beds form long shore-platforms beneath the cliff 

of Sandsfoot Clay south of Bincleave. They are 12 ft. thick and highly fossiliferous, 

but extremely hard. There is no exposure of this horizon on the shore 

of the Fleet. 

The Osmington Oolite Series is somewhat thinner than at Osmington, 

probably about 45 ft. thick. On the shore of the Fleet it contains interesting 

beds crowded with Isodonta triangularis (Phil.), not noticed elsewhere. 

According to Blake and Hudleston the total thickness of the Bencliff Grit 

1 1826, Ann. Phil., vol. xi, p. 349. 

2 1865, Versuch einer allgemeinen Classify p. 24.

CORALLIAN BEDS: NORTH DORSET 387 

m the type-section was 21 ft. 1 It consisted of sand and sandstone, rather more 

argillaceous in the lower part, with the usual band of hard sandstone doggers 

at the base. The Nothe Clay was estimated to be 40 ft. thick, and the Nothe 

Grits about 30 ft. This last estimate included any representative there may 

have been of the Trigonia hudlestoni Bed. No details are preserved, except that 

Blake and Hudleston stated that the downward passage to clay was abrupt. 

The hardness of the gritstone bands is the direct cause of the long, narrow 

promontory of the Nothe. On the shores of the Fleet the lower beds are but 

obscurely exposed in small discontinuous sections. 

(c) North Dorset 

The Corallian Beds reappear from beneath the Chalk Downs at the villages 

of Mappowder and Wootton Glanville, whence they strike north for 16 miles, 

the outcrop having a width of from one to three miles, and forming pleasantly 

undulating and wooded country rising above the clay vales on either side. 

At Mere, near the north end of this outcrop, the Corallian Beds and Kimeridge 

Clay are cut off by the fault bounding the north side of the Vale of Wardour, 

so that they end abruptly against the steep down of Greensand and Chalk. 

Northward for 12 miles they are hidden beneath it. 

In the southern half of the area the rocks are known only from a few 

unsatisfactory openings at Wootton Glanville, Mappowder and Hazelbury 

Bryant, most of them showing only a few feet of the Trigonia clavellata Beds. 

In the northern half of the area, however, the Osmington Oolite Series yields 

a good building stone, which is exploited in large quarries under the name 

of the Marnhull and Todber Freestone. A complete section near the centre 

of the area is afforded by the railway-cutting at Sturminster Newton, supplemented 

by a deep road-cutting by the river-side, south of the town. By 

combining the information derived from all these exposures, and from other 

quarries at Stour Provost, East Stour, Langham, Cucklington and Silton, the 

following sequence can be made out: 

SUMMARY OF THE CORALLIAN SERIES IN NORTH DORSET 2 


The only exposure known is in the Sturminster railway-cutting, at the top 

of which are 14 ft. of rusty yellow sand, much mixed with clay and soil. 3 

Traces of the same beds are evident at Silton and elsewhere. 


The Sandsfoot Clay is 8 ft. 6 in. thick in the Sturminster railway-cutting, 

and the base appears above the Trigonia clavellata Beds in East Stour Quarry. 

The Trigonia clavellata Beds are an important feature over the whole area, 

usually consisting of soft, shelly, rather marly limestones, crowded with wellpreserved 

lamellibranchs, as in the Weymouth district. In the Sturminster 

railway-cutting their total thickness is 15 ft. 

At Stour Provost and East Stour, 5 and 6 miles to the north, the total 

1 H. B. Woodward, in enlarging the Bencliff Grit to 35J ft. (1895, p. 89) included in it 

16 ft. of Littlemore Clay Beds clearly belonging to the Osmington Oolite Series and so 

classed by him at Shortlake and Black Head. 

2 Based mainly on field-notes and Blake and Hudleston. 

3 Blake and Hudleston, 1877, loc. cit., p. 276, fig. 2.


thickness has shrunk to ft., and the dark, soft, shelly beds are sharply demarcated 

from the underlying courses of white oolite, belonging to the 

Osmington Oolite Series. At these places Trigonia clavellata abounds, 

together with Chlamys qualicosta, Chlamys super fibrosa, Ostrea delta, Astarte 

morini, Nucula menkei, Cucullcea contracta, Trigonia reticulata, Gervillia aviculoidesf 

Nerinea sp., and numerous other bivalves as in the Weymouth district. 

At the north end of the district, at Silton near Bourton, and Preston, northwest 

of Gillingham, rolled corals become conspicuous, mixed with the same 

fossils as at the Stours. The commonest species belong to the genus Stylina, 

together with Thamnastrcea, Thecosmiliay &c. Another interesting feature 

here is the development of massive, doggery, blue-hearted calcareous grits, 

full of casts and impressions of Trigonia clavellata. This arenaceous facies is 

similar to the Gres d'Hennequeville and the Sables de Glos at the typelocality 

of the Glos Oolite Series on the coast of Normandy. At Silton there 

is also a local mussel-bank composed of the diminutive Mytilus varians Roem., 

elsewhere recorded only from Germany. 1 

Osmington Oolite Series. 

The downward passage from the Trigonia clavellata Beds, though more 

abrupt than in the Weymouth district, is not marked by any interruption in 

the bedding, the uppermost 10 ft. or so of the white freestones being evenbedded. 

Beneath this, however, the bulk of the Marnhull and Todber Freestone 

(15-20 ft. thick) is steeply false-bedded. It is a solid, creamy, finegrained, 

hard, oolitic limestone, blue where unweathered. Fossils are scarce, 

except for micromorphic forms (Isodonta triangularis, Limatula elliptica, 

Chlamys qualicosta, Exogyra nana) and drifted fragments. In the rare shelly 

bands gastropods, as usual, predominate. 

Underneath the Marnhull and Todber Freestone is a variable development 

of the Littlemore Clay Beds—bands of whitish rubbly claystone alternating 

with black clay. They are about 8 ft. thick at Sturminster, but thicken southward, 

where they seem to replace the freestone. In these beds, especially in 

the road-cutting at Sturminster, Nucleolites scutatus abounds, together with 

the rarer Acrosalenia angulata and Hemicidaris intermedia. 

At the base are a few feet of loose, marly, large-grained oolite and a band of 

coarse pisolite reminiscent of the Pea Grit of the Cotswolds; the pisoliths are 

flattened, and measure a third of an inch in diameter. The band floors the 

village square at Stour Provost, giving it a remarkable appearance. At 

Cucklington, in the w r est, the pisolitic beds thicken to about 12 ft. and yield 

a highly characteristic, coarsely pisolitic stone. 2 Fossils in these beds are 

uncommon (except for the ubiquitous N. scutatus and E. nana). Indecisive 

Perisphinctids occur, but rarely and in bad preservation. 

Berkshire Oolite Series and Lower Calcareous Grit. 

In the Sturminster neighbourhood the pisolite has been seen in several 

clear exposures (during road widening in 1927 on both sides of the town, and 

in the railway-cutting) to rest directly on grey clay, indistinguishable from 

Oxford Clay. It is possible, however, that this is an argillaceous development 

1 W. J. Arkell, 1929, 'Mon. Corall. Lamell.', Pal. Soc., pp. 52-3. 

2 A piece is figured, P.G.A., 1916, vol. xxvii, p. 132, pi. XXIII.

CORALLIAN BEDS: WESTBURY AND CALNE AREA 389 

of the Lower Calcareous Grit, for a short distance to the north grits appear, 

and, in the eastern entrance to the tunnel west of Gillingham, Blake and 

Hudleston saw 18 ft. of 'dark blue sandy marl, containing at various levels 

immense spheroidal doggers of calcareous grit, and sometimes thin layers of 

alternating sand and clay 5 . 1 Above this were noted 33 ft. of beds which also 

may represent parts of the Lower Calcareous Grit, or the Berkshire Oolite 

Series, or both, but the description and lists of fossils are insufficient for 

certain correlation. There do not seem to be any other exposures of beds 

below the level of the pisolite. 

II. THE WILTS.-BERKS.-OXON. RIDGE 2 

(a) The Westbury and Calne Area 

Just as in North Dorset an isolated range of Corallian Beds closes the 

mouth of the Vale of Wardour, so again at the mouth of the Vale of Pewsey 

the formation reappears for a stretch of 9 miles from Westbury to Seend; 

north of this is another gap, occupied by the Lower Greensand hills of Spye 

Park and Bromham. Beyond this the main outcrop begins near Calne and 

continues to Oxford. 

The area about Westbury, Seend and Calne contains such special features 

that it is best described separately. It includes the famous coral reef of 

Steeple Ashton, perhaps the most noted locality for corals in Britain, and also 

works at Westbury where the Corallian iron ore is smelted. 

SUMMARY OF THE CORALLIAN SERIES, WESTBURY TO CALNE 


Immediately beneath the Kimeridge Clay is the WESTBURY IRONSTONE, 

11-14 ft. thick. It consists of an oolitic, more or less argillaceous ore, varying 

in colour from dark reddish-brown to green, and yielding from 30 to 35 per 

cent, of iron. The fossils link it to the Sandsfoot Grit in general, and in 

particular to the Ringstead Waxy Clay and Coral Bed; and on the other side 

of the Channel to the ironshot oolite of Hesdin TAbbe, near Boulogne. 

Several species of Ringsteadia—R. anglica Salf., R. pseudocordata (Bl. and H.), 

&c.—are abundant, and there is in the Geological Survey collection a fragmentary 

Perisphinctid 3 resembling the true P. wartce Bukowski. Ostrea 

delta, Ctenostreon proboscideum, Chlamys midas, Camptonectes sandsfootensis, 

&c. also occur. The surface-extent of the ore is rather limited, but it is said 

to have been worked also in old pits on the high ground round the church at 

Steeple Ashton. At Calne there is no sign of it. 

Underneath the ore are from 4 ft. to 10 ft. of pale greenish-grey, buff and 

ferruginous sands, containing only casts of Pleuromya. 


At Westbury the Upper Calcareous Grit rests directly on rubbly grey and 

white oolite and pisolite apparently belonging to the Osmington Oolite Series. 

Farther north, at Broad Mead, near East Ashton, a reddish shell-bed appears 


2 Based on W. J. Arkell, 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, pp. 67-181; and 1928, 

Journ. Ecology, vol. xvi, pp. 134-49; and Blake and Hudleston, 1877, Q.J.G.Svol. xxxiii, 

pp. 283-313. 

3 No. 25484.

3QO MIDDLE OOLITES 

above the white oolite, containing drifted corals, Trigonia clavellata, Perna 

mytiloides, Chlamys inter text a, Limatula elliptic a, Trigonia ashtonensis, Prorokia 

problematica and perisphinctid fragments; this is evidently a continuation 

of the Trigonia clavellata Beds of North Dorset. Near Steeple Ashton 

the bed passes into a true coral reef—one of the reefs from which the rolled 

corals of East Ashton and North Dorset were derived. No excavation seems 

to have been made in the reef, all the specimens in various museums having 

been picked up on the surface of a field on the north side of a road turning 

SE. off the high road from Steeple Ashton to Bratton. The best specimens 

have long since been taken away, but every stone on the field is still a coral. 

The association is peculiarly rich in species, and the state of preservation, in 

a red earthy matrix, is better than at any other locality in England. Besides 

the common species, Isastrcea explanata (Goldf.), Thamnastrcea spp., Thecosmilia 

annularis (Flem.), several other corals are abundant, notably Comoseris 

irradians and Stylina tubulifera. 


The local reef at Steeple Ashton grew upon a foundation of thick white 

oolites, which can be seen in an old lime-kiln near by, beside the road 

leading south from the village. Here and at Westbury, as in North Dorset, 

the upper part of the oolites is even-bedded and the lower and larger part is 

false-bedded. The fossils, which are chiefly fragmentary, are all worn and 

coated with calcareous matter, and the beds are looser and more pisolitic than 

at Marnhull and Todber. 

FIG. 66. Diagrammatic representation of the Corallian rocks along the outcrop in the South 

of England, to show the horizontal and vertical distribution of coral rock. Coral: black; 

other deposits: dotted. Not to scale. (From W. J. Arkell, 1928, Journ. Ecology, vol. xvi, 

P. 135.) 

7 Upper Calcareous Grit 3 Bencliff Grit and Nothe Clay ^Berkshire 

6 Sandsfoot Clay iGlos Oolite 2 Trigonia hudlestoni Beds /Oolite Series 

5 Trigonia clavellata Beds J Series 1 Lower Calcareous Grit 

4 Osmington Oolite Series 

The best section in the Osmington Oolite is a large quarry (now unfortunately 

closed) behind the workhouse at Calne, which formerly showed 25 ft. 

of false-bedded oolites, yielding the CALNE FREESTONE, a material at one time 

much used locally for building. In the base of this quarry was encountered 

a remarkable colony of fossil sea-urchins. The tests of some species, especially 

Hemicidaris intermedia, which are usually found only singly, were congregated 

by the hundred, spread thickly over the bedding-planes of the stone. 

The species represented were H. intermedia, Cidaris florigemma, C. smithii, 

Acrosalenia decoratay Glypticus hieroglyphicus, Diplopodia versiporay Stomechinus 

gyratus, Pseudodiadema pseudodiadema, and P. mamillanum} 

The Calne Freestone with its hosts of echinoderms was laid down on the 

fringe of the great chain of coral reefs that extended through North Wiltshire 

1 A fine collection may be seen in the Wiltshire Museum, Devizes. 

6 

5 

A 

3 

1

CORALLIAN BEDS: WESTBURY AND CALNE AREA 391 

and Berkshire to Oxford. Near by can be studied the passage from the Dorset 

type of oolite to the coral rag so typical for the next 40 miles, and a very 

illuminating spectacle it provides for the geologist. First Lonsdale and after 

him Blake and Hudleston described it, beside a brook that runs down from 

Quemerford and thence towards the town. The oolite and pisolite gradually 

pass laterally into beds of more obviously detrital materials, with which lenticles 

of coral rag are intercalated, until eventually the coral rag predominates. 

Another facies, that of the Littlemore Clay Beds, is developed 3 miles north 

of Calne, at Hilmarton, where bands of white argillaceous limestone and clay, 

containing the Osmington Oolite fauna, recall the typical development at 

Littlemore. The occurrence of the clay beds coincides with an excessive 

narrowing of the outcrop, and at this point a brook has cut an opening through 

the Corallian escarpment—features commonly associated with the local 

passage of the relatively resistant oolites and coral rag into soft clays. 

Berkshire Oolite Series, 

A deep boring at Westbury proved 40 ft. of'clays beneath the Osmington 

Oolite and above the Lower Calcareous Grit. 1 Some of this clay (22 ft. out of 

the 40 ft.) may be accounted for as an argillaceous development of the lower 

part of the Osmington Oolite Series—a partial passage into Littlemore Clay 

Beds such as is usual in Dorset. Two quarries almost due west of Hilmarton, 

upon an outlying ridge of Corallian rocks, however, give a definite indication 

that the Nothe Clay and at least locally the Bencliff Grit are well developed, 

as on the Dorset coast. This ridge, known as Spirt Hill, is the key to the 

sequence in this part of Wiltshire. The high plateau of Bradenstoke and 

Lyneham to the north is formed of the coral rag resting upon a thin bed of 

oolite and pisolite. But at Spirt Hill the Osmington Oolite Series, having 

probably consisted of Littlemore Clay Beds as at the neighbouring village of 

Hilmarton, has been entirely stripped from its summit; instead, the crest of 

the hill is formed of yellow sand perhaps 15 ft. thick. Below the sand are 

about 12 ft. of grey-green mottled clay, the lowest 8 ft. of which are seen in 

a quarry, resting on a remarkable Pebble Bed, with the coarse, false-bedded 

sands and doggers of the Lower Calcareous Grit beneath. At the base of the 

clay is an impersistent band of tough oolitic limestone, yielding only Chlamys 

fibrosa. The general appearance and poverty of fossils recall the Nothe Clay 

of Redcliff Point, and the presence of the representative of the Bencliff Grit 

at the top of the hill, exposed in a small sand-pit, completes the analogy. 2 

The PEBBLE BED, which henceforth provides a valuable stratigraphical 

datum, is an interesting stratum. Consisting of a seam of large water-rolled 

pebbles, packed close together in a soft clay matrix, it has here a thickness of 

only 4 in., but in many places it is up to 1 ft. thick, and it is traceable in almost 

every exposure at which the horizon is to be seen as far as Oxford, a distance 

of 40 miles. The pebbles are well bored by Lithophaga inclusa and often 

encrusted with Serpulce and Exogyra nana. They are of three sorts. The 

largest and most conspicuous, which vary in diameter from about 1 in. to 


2 W. J. Arkell, field-notes. After this book had gone to press my attention was called to 

a cutting on the new loop-line at Westbury, where the Pebble Bed has been exposed at its 

most southerly point, combined with a Gervillia and Trigonia bed, separated from the 

oolite by about 12 ft. of clay and marl.


4 in., averaging perhaps in., consist chiefly of hard, compact claystone, 

recalling the hard crackers so common in the Oxford Clay. The derivation of 

at least some of them from the denudation of Oxford Clay is proved by the 

discovery of a specimen of Nucula in one at Littleworth, Berkshire. Locally 

some of the largest consist of indurated calcareous gritstone, evidently the 

product of erosion of already-consolidated Lower Calcareous Grit. The third 

sort are much smaller and consist of extremely hard black 'lydite' and white 

vein-quartz, of indefinite Palaeozoic origin. These last are identical with 

many to be seen in the sands of the Lower Calcareous Grit, whence they have 

doubtless been rederived. 1 

The Pebble Bed at Spirt Hill is especially interesting on account of its 

containing a number of oysters. The commonest are Gryphcea dilatata, 

together with Lopha gregarea and Ctenostreon proboscideum, all of which are 

common to the Corallian and the Upper Oxford Clay. In addition, however, 

there are specimens of Gryphcea lituola Lamk., the much more incurved and 

narrower species characteristic of the Middle Oxford Clay, and not known 

elsewhere above the athleta zone. The presence of this species and also the 

segregation of so many oysters of different species in a thin seam with waterworn 

pebbles suggests that the fossils have been derived from the erosion of 

Oxford Clay, but against this must be set the fact that they do not appear to 

have been rolled. 

In North Wiltshire, immediately succeeding the Pebble Bed, coral reefs 

occur, separated by representatives of the Nothe Clay and Bencliff Grit from 

the Osmington Oolite coral rag above. Coral growth of this early Berkshire 

Oolite period may be represented in the Calne district by a reef at Westbrook, 

which Blake and Hudleston believed to be of earlier date than the rest of the 

coral rag in the neighbourhood. Their belief was based on the observations 

that Cidaris florigemma, usually the predominant urchin of the rag, was here 

replaced by C. smithii; and that the reef grew directly upon sand, which they 

took to be the Lower Calcareous Grit. This correlation is probably correct, 

but in view of the presence of Bencliff Grit at Spirt Hill, careful work will be 

required before the matter can be finally settled. The old limekilns on Sandridge 

Hill, Westbrook, are now overgrown by a wood, but fortunately they 

were vividly described by Blake and Hudleston, and whether the rocks they 

showed should properly be classed with the Berkshire Oolites or with the 

Osmington Oolites above, they illustrated so well the nature of the Jurassic 

coral reefs that Blake and Hudleston's description may appropriately be 

quoted. 

* Layer upon layer of large masses of Thamnastrcea concinna and Isastrcea explanata/ 

they wrote, ' bored by the characteristic Lithophaga inclusay and changed 

not seldom into crystalline limestone in which the organic structure is no longer 

visible, here spreads over the surface, resting immediately upon a bed of sand. . . . 

The spaces between the coral growths are filled with rubbly brash, made up of 

comminuted materials, and sometimes with clay charged with fragments of shells. 

These intercoralline accumulations obtain the mastery here and there; corals disappear, 

and we have great rubbly beds of shelly clay and limestone brash forming 

the whole reef.' 2 

1 For full discussion of the Pebble Bed see Arkell, 1927, loc. cit., pp. 80-4. 

2 Blake and Hudleston, 1877, loc. cit., p. 288.

Lower Calcareous Grit. 

CORALLIAN BEDS: PURTON AXIS 393 

The Lower Calcareous Grit covers several square miles of ground in Bowood 

Park, where it probably attains its greatest thickness. From 25-30 ft. 

of yellow sands with bands and doggers of hard grey or blue-hearted gritstone 

are worked at Seend Cleeve, Derry Hill, Conygre Farm and Bremhill. The 

hard bands contain Cardioceras cordatum and Nautilus hexagonus, and at 

Seend an unusually large fauna of lamellibranchs is found: Gryphcea dilatata, 

Ostrea quadrangular is, Chlamys fibrosa, Gervillia aviculoidesy Pseudomonotis 

ovalisy Oxytoma expansa and a number of other species, principally from 

a shelly band at the top. 

(b) The Purton Axis 

A short distance north of Spirt Hill and Hilmarton the Corallian rocks 

form a marked feature in the landscape, rising about Lyneham and Bradenstoke 

well above the 400 ft. contour as an elevated plateau, nearly 4 miles wide. 

This change is directly due to two causes: to the thick development of coral 

rag and oolite in the Osmington Oolite Series, and to the disappearance of the 

soft substratum of Nothe Clay. Typical sections may be seen at Tockenham 

Wick, beside the main road from Lyneham to Wootton Bassett. The coral 

rag, with some strong bands of white oolite, rests directly on the Lower 

Calcareous Grit, with the intervention only of the Pebble Bed. 

A short distance south-west of Wootton Bassett the outcrop rapidly narrows 

once more and the Oxford and Kimeridge Clays are mapped as if they were 

in contact, the Corallian formation having entirely disappeared. The gap in 

the Corallian ridge is utilized by the Wilts, and Berks. Canal and the Great 

Western Railway. Fortunately, when the new railway to the Severn Tunnel 

was constructed, a fresh cutting was made close to the gap, west of Wootton 

Bassett Railway Station, and was described by Messrs. Reynolds and Vaughan 

before it became grassed over. From their description it seems that the 

gap is caused by the lateral passage of the Osmington Oolite Series into 

Littlemore Clay Beds, as at Hilmarton. 1 At the same time, from north of 

Spirt Hill the Lower Calcareous Grit has disappeared or become thinner 

and passed into clay. 

North of Wootton Bassett the outcrop widens once more towards Purton, 

becoming again a high plateau with a steep escarpment overlooking the clay 

vale occupied by Braydon Forest. Quarries are numerous, and they all show 

massive limestones built up of comminuted shells and coral fragments, passing 

here and there into coral reefs. The detrital limestones, from their great 

development at Wheatley near Oxford, have been called the Wheatley Limestones, 

and in this part of England they are a striking facies of the Osmington 

Oolite Series. Quarries south of Purton Church (fig. 67) show how lenticles 

of growing coral became established from time to time upon the accumulating 

banks of debris, only to be repeatedly smothered by fresh accretions at every 

change in the prevailing currents. Near by, other openings show coral islets, 

built up of masses of well-preserved Isastrcea explanata, Comoseris irradians 

and Thamnastrcea concinna, still in the positions in which they grew. 

The patches or islets of corals in the Purto'i district seem to be completely 

isolated among detrital limestones, the products of the grinding of the coral 

1 S. H. Reynolds and A. Vaughan, 1902, Q.J.G.Svol. lviii, p. 751.


reefs by the waves. In some places the corals 

grew out over a substratum of detritus; in 

others the debris covered them partially or 

closed above them. The reefs are of fringing 

reef type, but are difficult to classify mote 

accurately in terms of modern coral structures 

. Their thickness probably never exceeds 

25 ft. and is usually less, and their distribution 

seems to have been haphazard. Darwin 

wrote concerning certain modern fringing 

reefs: Tt follows ... that where the sea is very 

shallow, as in the Persian Gulf and in parts of 

the East Indian Archipelago, the reefs lose 

their fringing character and appear as separate 

and irregularly scattered patches, often of 

considerable size.' 1 That the sea was shallower 

than usual in the Purton district is 

certain on stratigraphical grounds, and this 

passage of Darwin's seems singularly applicable. 

Two miles east of Purton the outcrop for 

the third time narrows suddenly and there is 

a gap in the Corallian escarpment, utilized by 

another branch of the canal and by the railways 

from Swindon to Cheltenham and 

Cirencester. Here again the Oxford and 

Kimeridge Clays have been mapped as if in 

contact. But one of the railway-cuttings was 

seen by H. B. Woodward, who described 

about 20 ft. of clay with bands of 'grey earthy 

limestone 3 , 'compact coral rock' and 'rubbly 

irregular grey marly and septarian limestone', 

the whole full of typical Corallian fossils. 2 

Evidently the gap is again caused by a lateral 

change of facies of the Osmington Oolite 

Series into Littlemore Clay Beds. 

To the east another high plateau of coral 

rag and Wheatley Limestones juts northward 

into the vale, about Broad and Little Blunsdon. 

A useful section in a well sunk into it 

showed that the Osmington Oolite Series is 

still separated from the Lower Calcareous 

Grit by nothing more than a thin Pebble 

Bed, as at Purton and about Lyneham and Tockenham. 

It is concluded, therefore, that over this area deposition was arrested while 

the Berkshire Oolites were being laid down from Highworth north-eastward 

on the one hand and from Spirt Hill south-westward on the other. The best 

1 Charles Darwin, Coral Reefs, 3rd ed., 1889, pp. 77-8. 

2 H. B. Woodward, 1895, J.R.B., p. 117.

CORALLIAN BEDS: PURTON AXIS 395 

explanation seems to be that the sea was shallower owing to an axis of uplift 

(the Purton or Wootton Bassett Axis) and it may be significant that the area 

coincides with the continuation of the Woolhope-May Hill line of uplift in 

the Palaeozoic rocks far to the north-west (see p. 80). 

The Upper Calcareous Grit of the area of the Purton Axis is very little 

known. Sands, bright red in colour and separated from the coral rag by clay, 

begin north of Hilmarton and continue to Wootton Bassett. An old brickyard 

at Wootton Bassett, long since obscured, yielded a number of Ringsteadia, in 

addition to Pictonice (indicating the basal zone of the Kimeridge Clay). A 

predominantly argillaceous development of the Upper Calcareous Grit was 

also proved by the deep boring at Swindon. At the base of the Kimeridge 

Clay were 6 in. of'grey and brown earthy limestone with patches of ironshot 

grains', containing Prionodoceras serratum, and evidently a representative of 

the Westbury Iron Ore, separated by 21 ft. 6 in. of clay from the top of the 

Osmington Oolite Series; 1 and an identical succession was encountered by 

a boring on Red Down, near Highworth. 2 

The Lower Calcareous Grit, which forms such a conspicuous feature from 

the Seend and Calne districts, on by Bremhill to Spirt Hill, is absent over 

most of the area affected by the Purton Axis. It was proved entirely absent by 

the railway-cutting at Wootton Bassett and again by a well at Purton, and it 

is not represented on the Survey map except in two patches; one patch, seen 

under the Pebble Bed in the quarries at Tockenham Wick, also extends on 

to the outlier of Grittenham Hill, while the other patch forms Paven Hill, 

Purton, and the bluff on which Ringsbury Camp is cut. This last patch is of 

great interest, for it consists largely of a non-calcareous deposit of siliceous 

sponge-spicules ('Rhaxella chert') similar to the Arngrove Stone of Oxfordshire, 

to be described in a later section. It differs from the Oxfordshire rock, 

however, in the presence of large scattered ooliths, converted to limonite. 

(c) Highworth-Faringdon-Marcham (The Faringdon Ridge) 

Only 2 miles to the west of the well in the middle of the Blunsdon plateau, 

where the Berkshire Oolite Series seems to be represented solely by the 

1 The Osmington Oolite Series at Swindon is in the facies of Littlemore Clay Beds; see 

Arkell, 1927, loc. cit., p. 146; the account by Whitaker and Edmunds there referred to (' Water 

Supply of Wilts.', Mem. Geol. Surv.y 1925, pp. 85, 86) is the old misleading version, in which 

the 21 £ ft. of clay and overlying 6 in. of ironshot oolite are grouped as Kimeridge Clay; for 

the revised grouping see Messrs. Chatwin and Pringle's account, 1922, Sum. Prog. Geol. 

Surv. for 1921, p. 164. The ironstone band was encountered by William Smith in the boring 

for water in the Vale between Swindon and Wootton Bassett, for which he was adviser in 

1816-17 (J» Phillips, 1844, Memoirs of William Smith, p. 85, where it is duly entered in the 

diagram). 

Salfeld misquotes Woodward as saying that this ironstone band with P. serratum was found 

in Oxford Clay in a cutting on the M.S.W. Jn. Rly. (now G.W.R.) west of Rodbourne Cheney. 

He then remarks "was hier Oxford Clay soil, ist mir vollig unklar\ Woodward says nothing 

of the sort; he is clearly referring to the deep boring at Swindon and he definitely states 

'Towards the base of what we included in the Kimeridge Clay at Swindon, there was a bed 

of iron-shot earthy limestone, six inches in thickness, which yielded Ammonites cordatus, var. 

excavatus [serratus], a well-known Lower Kimeridge fossil, though found here [also] in the 

Oxford Clay* (i.e. in the deep boring; see p. 37, where a Cardiocerate is listed from the Oxford 

Clay under this name). Woodward makes no mention of the ironstone band having been found 

in the Rodbourne railway-cutting, which was entirely in earlier beds. (H. B. Woodward, 

1895, J.i^B., pp. 37, 118; H. Salfeld, 1914, Neues Jahrb. fur Min.t B-B, xxxvii, p. 196.) 

2 For the Highworth boring see W. J. Arkell, 1927, Wilts. Arch. Nat. Hist. Mag.}\ol.xliv, 

PP. 43-5> 

H.-)4:*71 E E


Pebble (or Shell-cum-Pebble) Bed, i ft. 6 in. thick, the full sequence is developed 

about Highworth. For the next 20 miles the Berkshire Oolite Series 

is the chief centre of interest in the geology. It builds the greater part of the 

hills about Highworth, Hannington and Coleshill, reaching 30 ft. in thickness, 

and thence, thinner but maintaining its characteristics, it appears in all the 

quarries along the Faringdon ridge as far as Cumnor and Marcham, on the 

borders of Oxfordshire. Its rich shell-beds yield some of the best specimens 

of the Corallian fauna to be obtained in the country. The.Pebble Bed may be 

seen at the base, resting discordantly upon the false-bedded sands of the 

Lower Calcareous Grit. The Osmington Oolite Series coral rag continues 

unchanged above, but with its outcrop receded somewhat down the dip-slope, 

instead of lapping up to the edge of the escarpment as it does over the Purton 

Axis. 

SUMMARY OF THE CORALLIAN ROCKS OF THE 

HIGHWORTH-MARCHAM AREA 

Upper Calcareous Grit and Glos Oolite Series. 

The Upper Calcareous Grit is most fully developed at Shrivenham, near 

Highworth, where the Berkshire Oolites also attain their thickest development. 

There are now no good exposures, but the ferruginous sands form 

a distinct escarpment rising above the coral rag plateau at Sandhill Farm and 

round the north and west of the village. Several wells at Shrivenham proved 

up to 35 ft. of ferruginous sandy beds interdigitating with clays before the 

coral rag was reached. 1 During the construction of the Wilts, and Berks. Canal, 

and probably also in the excavation of the pits to obtain materials for the 

railway-embankment south-east of South Marston, an oolitic ironstone like 

that at Westbury and Swindon was encountered. Ringsteadice collected here, 

some of them by Dean Buckland, are preserved at Oxford and in London, 

and were mentioned by Salfeld in his monograph of the genus. One species 

was named Ringsteadia marstonensis Salf. 2 

The correspondence of this oolitic ironstone with the Westbury Iron Ore 

can hardly be questioned, and the 35 ft. of underlying beds together represent 

the Sandsfoot Grit and Sandsfoot Clay. To the north and west the argillaceous 

element predominates. An outlier at Red Down, near Highworth, is capped 

with 20 ft. of clay giving a bright-red soil, overlain by a thin band of Westbury 

Ironstone, just as at Swindon. 3 

Towards the east the Upper Calcareous Grit is rapidly overstepped by the 

Kimeridge Clay. At Faringdon all that remains is about 2 ft. of 'reddishbrown 

and chocolate-coloured ferruginous earth, with black stains from 

dissolved fossils, and lumps of calcareous clay, ironstone, and fragments of 

Ostrea delta and Serpula towards the base', resting upon the surface of the 

coral rag. 4 A reddish soil is noticeable above the coral rag about Shellingford 

and Stanford, but nothing is seen east of Shrivenham that could be called 

undisturbed Upper Calcareous Grit. 

Although the Trigonia clavellata Beds have nowhere been definitely proved, 

1 'Water Supply of Berks.', Mem. Geol. Surv., pp. 73-4. 

2 H. Salfeld, 1917, Palaeontographica, vol. Ixiii, p. 83. 

3 Compare Arkell, 1927, Wilts. Arch. Nat. Hist. Mag., vol. xliv, pp. 43-5, and Chatwin 

and Pringle, 1922, loc. cit., p. 164. 


CORALLIAN BEDS: FARINGDON RIDGE 397 

records of a shell-bed immediately above the Osmington Oolite Series in the 

Swindon boring and again in one of the wells at Shrivenham are suggestive. 


The Osmington Oolite Series is continuous throughout the area and consists 

for the most part of coral rag of somewhat monotonous appearance. The 

corals are often in the position of growth and seem to have formed a thin 

fringing reef. Some of the mollusca may be obtained in exceptionally perfect 

condition, especially the large gastropods, which lie w T here they dropped in 

the interstices among the corals. At Kingsdown a small colony of Terebratula 

kingsdownensis Ark. has been found. 1 

The majority of the mollusca associated with the corals belong to a few 

species, and they are met with over and over again, in all the quarries. The 

principal constituents of the coral-dwelling fauna are Chlamys nattheimensis 

(de Lor.), Lima zonata Ark., Lithophaga inclusa (Phil.), Lophagregarea (Sow.), 

Exogyra nana (Sow.) and Littorina muricata Sow. Of these the first two, 

although extremely abundant in their natural habitat, have scarcely ever been 

found unassociated with corals, while the oysters and Littorina are much more 

abundant about the reefs than elsewhere. The corals that enter most conspicuously 

into the composition of the reefs are Thecosmilia annularis (Flem.), 

Thamnastrcea arachnoides (Park.), Th. concinna (Goldf.), and Isastrcea explanata 

(Goldf.). 2 

In two areas, the one about Highworth, the other from Faringdon to 

Kingston Bagpuize, the coral rag rests discordantly upon thinly false-bedded, 

fissile, sandy oolites—the PUSEY FLAGS. About Pusey and Buckland these 

flags reach a thickness of 10-15 ft., and contain a rich micromorphic fauna, 

comprising Protocardia dyonisea (Buv.), Isodonta triangularis (Phil.), Opis 

phillipsi d'Orb., Chlamys fibrosa (Sow.), Pseudomonotis ovalis (Phil.), &c. 

Rarely Perisphinctids of the type of P. martelli Oppel are found. 

In 1927 I regarded the Pusey Flags as a link between the Bencliff Grit and 

the Osmington Oolite Series; 3 but as they pass down gradually into the 

Highworth (= Bencliff) Grit, and as the junction between them and the coral 

rag above is abrupt and discordant, I grouped them with the Berkshire Oolite 

Series. When the relations of the Pusey Flags to the underlying beds are 

studied over the w r hole area, however, it is seen that they overstep the other 

members of the Berkshire Oolite Series unconformably and come to rest 

at Pusey directly upon the Lower Calcareous Grit (fig. 68). Moreover, 

locally they lose their sandy character and become almost a pure oolite, 

suggesting rather the false-bedded lower portion of the Osmington Oolite 

Series farther south (the Marnhull and Todber Freestone). Throughout 

North Dorset and South Wiltshire the false-bedded oolitic freestone is overlain 

by an even-bedded series, the line of junction being very straight and stronglymarked. 

It may well be that only the upper or even-bedded portion of 

the North Dorset Osmington Oolite Series is represented by the coral rag 

of the Highworth-Faringdon-Marcham district, the Pusey Flags representing 

the lower, false-bedded portion. 

1 W. J. Arkell, 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, pi. 1, fig. 6. 

2 For an account of the coral fauna and some aspects of coral reef ecology in the Corallian, 

see W. J. Arkell, 1928, Journ. Ecology, vol. xvi, pp. 134-49. 

3 1927, loc. cit., p. 159, table.

MARCHAM MARCHAM fRILFORD 

KINGSTON 

BAGPUI2E 

2 MlltS. OF 

fox 8, HOUNDS 

WINDMILL 

QUARRY 

WORKHOUSE 

QUARRY 

LITTLEWORTH FARINGDON FARINGDON 

FIG. 68. Exposures of the Berkshire Oolite Series and of the Pusey Flags between Marcham and Faringdon, Berks, (I I miles). Note 

how the Pusey Flags cut down non-sequentially on to Lower Calcareous Grit about Pusey and Buckland, and elsewhere the ubiquitous 

Pebble Bed at the base. (From J. Arkell, 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, p. 102, fig. 5.)


It appears from surface-indications that south-west of Sevenhampton the 

coral rag oversteps all the underlying beds and comes to rest on the Oxford 

Clay. 1 

Berkshire Oolite Series. 

The Bencliff Grit and the Nothe Clay, last seen at Spirt Hill on the far side 

of the Purton Axis, reappear at Highworth, where they have been called the 

HIGHWORTH GRIT and HIGHWORTH CLAY. Together they measure 10-12 ft. 

in thickness, consisting of fine grit-sands, with some doggers, passing down 

gradually into clay. Most of the water-supply of the old part of the town was 

derived from the top of the clay, being tapped by means of numerous shallow 

wells sunk through the coral rag and the subjacent sands. The clay, too, 

supported two rival brick industries, on the north and south sides of the town. 

The ruins of the extensive excavations may still be seen beside the road to the 

station and north of Redlands Court (fig. 69). The upper portion of the sands 

is false-bedded and can be seen to interdigitate with the Pusey Flags, which 

at Highworth are only 2 ft. thick. Occasional specimens of Ostrea quadrangularis 

and Gryphcea dilatata are almost the only fossils. 

For some 3 miles about Faringdon the Highworth Grit and Clay are absent, 

apparently having been overstepped by the coral rag, but they reappear in the 

Windmill Pit, miles east of Faringdon, in the same thickness as at Highworth. 

In another 2 miles to the east they have been again overstepped by the 

Pusey Flags, about Pusey and Buckland, but they come in again at the Lamb 

Inn Quarry, Kingston Bagpuize, before finally disappearing towards Marcham 

and Oxford. 

Beneath the Highworth Clay, in all the quarries where it is seen, are some 

thin beds known as the URCHIN MARLS. These consist of drab grey marls, 

variously divided into harder and softer bands, all largely composed of wellformed 

ooliths and always distinguishable by being crowded with the small 

urchin, Nucleolites scutatus. Their characteristic colour, their densely oolitic 

texture and the inevitable urchin, render them an easily recognized division 

from Highworth through Berkshire (including Shellingford where the Highworth 

Grit and Clay are absent) to Marcham and Garford, a distance of 

18 miles. The thickness is 4 ft. at Highworth, 5 ft. at Marcham and the Noah's 

Ark, Garford (where also Pygaster semisulcatus is frequently associated with 

the more common Nucleolites). 

Finally come the TRIGONIA HUDLESTONI LIMESTONES, 2 the most interesting 

part of the Berkshire Oolite Series, with the Pebble Bed at the bottom. They 

attain their maximum thickness of about 8-10 ft. at Highworth, and may be 

followed in a score or more of quarries along the Berkshire ridge to Marcham, 

Garford and Cumnor, everywhere crowded with a rich assemblage of fossils. 

The best exposures were until recently the South Quarry, Highworth, and 

a second large quarry opened since the Great War at Hangman's Elm, beside 

the road to Shrivenham, miles south-east of Highworth. From these 

excavations, and from others actively worked at various points along the outcrop, 

especially at the Lamb Inn, Kingston Bagpuize, many mollusca have 

1 W. J. Arkell, 1927, loc. cit., geological map. 

2 Formerly called the Trigonia perlata Limestones, owing to an error in identification by 

Lycett; see Arkell, 1930, 'Mon. Corall. Lamell.', Pal. Soc.y part 2, p. 73.

4oo MIDDLE OOLITES 

been collected. The almost endless variety of Perisphinctids still remain to 

be worked out, but it is evident that they belong to the assemblage of the 

transversarius zone of the continental Argovian. Perhaps the most commonly 

represented is Perisphinctes helence De Riaz, with which are associated numerous 

forms approaching P. plicatilis, P. martelli, P. cloroolithicus, P. aripripes, 

P. maximuSy P. orientale, P. parandieriy and the true P. biplex Sowerby (a much 

misinterpreted species). The Cardiocerates include the excavatum type (C. 

highmoori and others), the maltonense type, and the vertebrale type (Vertebriceras 

of Buckman). There are also Aspidocerates of several species. 

Besides the ammonites, shell-banks composed of masses of lamellibranchs 

provide an attractive field for the palaeontologist. Trigonia hudlestoni and 

Trigonia reticulata form a Trigonia Bed at Marcham and Kingston Bagpuize, 

and with them are always associated Gervillia aviculoides, Isognomon mytiloideSy 

the large Limas, L. rigida and L. mutabilisy Chlamys splendens, C. 

fibrosa, Astarte ovata and many other shells. 

Many of these fossils, including the highly characteristic Perisphinctes 

helence De Riaz, have been collected in the Trigonia hudlestoni Bed at Redcliff 

Point, near Weymouth, and the lithological resemblance of that bed to the 

gritty, sparsely-oolitic, greyish, shelly 'fucoidal' limestones at Highworth is 

unmistakable. 

In the old South Quarry, Highworth, two beds of rolled Thecosmilian 

corals, together about 2 ft. thick, are intercalated in the shelly limestones 

(fig. 69). When the new quarry at Hangman's Elm was opened these were 

found to have coalesced and thickened to a bed nearly 3 ft. thick, chiefly composed 

of the corals Thecosmilia annularis and Montlivaltia dispary unrolled and 

in fine preservation among clay. It was then found that near by, at Upper 

Farm, the Trigonia hudlestoni Limestones pass laterally in a short distance into 

a small coral reef or islet. Detailed mapping has revealed that several islets 

exist in the Trigonia hudlestoni Limestones in the neighbourhood of Highworth; 

another is situated on the north side of Red Down, and a third (perhaps 

the continuation of the same one) on Staplers Hill, north-west of 

Hannington Railway Station. They are only a few fields in extent, but they 

can infallibly be recognized by the abundance of corals on the freshlyploughed 

land, while the normal assemblage of lamellibranchs and ammonites 

is noticeably wanting. Small quarries give good sections of two of the reefs, 

showing typical coral rag, not only composed of the same species of corals 

as the coral rag of Osmington Oolite date, but also containing the same 

molluscan 'coral fauna'—Lima zonata, Chlamys nattheimensis and the rest, 

with spines of Cidaris florigemma and C. smithii. From internal evidence 

alone, therefore, these earlier reefs are indistinguishable from the more widespread 

rag of Osmington Oolite date, although the two are separated by the 

Urchin Marls, the Highworth Grit and Clay, and the Pusey Flags. 

In the immediate neighbourhood of Faringdon and Coleshill the Trigonia 

hudlestoni Limestones take on a somewhat deeper-water facies, consisting of 

uniform white oolite, with the shells more sparsely distributed. This has 

been termed the Faringdon Facies. The limestones of the Highworth 

district bear a closer resemblance to those of Kingston Bagpuize than to those 

at Faringdon, and at Kingston fragments of coral are again found in the 

Trigonia bed.


At the eastern extremity of the district, at Marcham, Cothill and Cumnor, 

the Trigonia hudlestoni Limestones become highly charged with sand, and the 

Trigonia Bed is split into two by 2-4 ft. of interlaminated sand and clay. In 

FIG. 69. Section of the Berkshire Oolite Series in the old South Quarries, 

High worth, showing two coral beds in the Trigonia hudlestoni Limestones. 

(From Arkell, 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, p. 108, fig. 6.) 

this part of the district, too, a new feature is introduced, in the form of an 

impersistent Natica Band. It is best developed at Cumnor and near Cothill, 

and consists of up to 6 ft. of hard calcareous gritstone enclosing myriads of 

casts of Natica (Ampullina) arguta, Ceritella cost at a, Cloughtonia condensata,


and other gastropods. It was classed with the Lower Calcareous Grit until 

1930, when the enlargement of the quarry at Cumnor revealed lenticles of the 

Pebble Bed beneath it. Previously a second impersistent layer of rolled 

pebbles above had been mistaken for the true Pebble Bed, but it is now 

established that the peculiarly fine conglomerate sometimes obtained in parts 

of the quarry occurs cemented on to the under side of the Natica Band. 1 

The Pebble Bed here is typical of that exposed in nearly every quarry from 

Oxford to Spirt Hill. The commonest pebbles are the usual rounded to rather 

flattish lumps of grey claystone, together with gritstone, lydite'and vein-quartz 

derived from the Lower Calcareous Grit. A unique pebble, about z\ in. long, 

was found at the Lamb Inn Quarry, Kingston Bagpuize: a microporphyritic 

soda-rhyolite, consisting of small crystals of albite in a microlithic, finetextured, 

black, silicified matrix. 2 Indications of a special fauna associated 

with the Pebble Bed are found only at the Lamb Inn Quarry, Kingston Bagpuize, 

where the pebbles are disseminated through 2 ft. 8 in. of pisolitic rock, 

containing round-whorled Perisphinctids of Buckman's genus Cymatosphinctes 

(? = Kranaosphinctes), not found in the overlying beds, and also 

a peculiar Aspidocerate, A. (Euaspidoceras) crebricostis Ark. 3 

Lower Calcareous Grit. 

The Lower Calcareous Grit consists of the usual yellow sands, with impersistent 

bands and doggers of hard gritstone. False-bedding is common and 

is often observed to pass through the doggers, thus proving their secondary 

origin by some chemical process, which has either concentrated calcareous 

cement, or partly decalcified and removed cement from the surrounding 

material, reducing it to sand. The top of the Lower Calcareous Grit is seen 

in large numbers of sections, but deeper exposures are rare. The best are at 

Marcham, where for many years large collections of fossils haver been obtained, 

especially the well-known Aspidoceras (.Euaspidoceras) catena, Nautilus 

hexagonus, Pachyteuthis abbreviatus, and Cardioceras excavatum. Drifted 

wood, often in logs of considerable size, fruits of Carpolithes and vertebrae of 

Teleosaurus occur. The false-bedding is especially noticeable at Marcham and 

in Tubney Wood, as is also the quantity of small pebbles of lydite and veinquartz. 

Both the proportion of pebbles and the degree of false-bedding 

diminish westwards, from w rhich it is deduced that the source of the sands lay 

in the south-east. The deposit is a sandbank, the materials of which were 

presumably brought down by some large river, flowing from the landmass 

occupying the site of the London Basin and the North Sea. It dropped the 

greater part of its heavier materials on entering the sea, the lighter constituents 

being carried by a long-shore current south-westward into Wiltshire. 

The thickness of the Lower Calcareous Grit is very variable in the east, 

about Oxford. A boring proved the thickness to be only 11 ft. at Wootton 

Waterworks, but it is probably nearer 50 ft. at the edge of the escarpment 

about Cumnor, and a boring at Frilford proved 52J ft. Thence it increases 

gradually towards Faringdon, where three borings at Faringdon, Goosey and 

Shrivenham proved 70 ft., 79 ft., and 76 ft. respectively. This is the area of 

1 W. J. Arkell, 1931, P.G.A., vol. xlii, pp. 44-9. 

2 Ibid., p. 51. Identified by Dr. H. H. Thomas. 

3 W. J. Arkell, 1927, loc. cit., pp. 96-7.

CORALLIAN BEDS: OXFORD AXIS 403 

maximum thickness, beyond which a more rapid diminution sets in towards 

the Purton Axis. In 3 miles, at Highworth, the borings prove 20-30 ft.; 

4 miles farther, on the slopes of the Blunsdon plateau, 10-20 ft. is the usual 

thickness; while in another mile the Lower Calcareous Grit dwindles to 

a parting of sand and finally disappears against the axis. 

It is noteworthy that the area in which the Lower Calcareous Grit attains 

its maximum thickness coincides with the area in which the Berkshire Oolite 

limestones take on the Faringdon Facies, thought to indicate deposition in 

deeper water. 1 

(d) The Oxford Axis 

The Corallian rocks in the area immediately surrounding Oxford bear 

a strong resemblance to those about Purton. The thickness of the Lower 

Calcareous Grit becomes very variable: although in some places it is as much 

as 50 ft., in others it diminishes to less than 12 ft. The Berkshire Oolite 

Series, so important a feature in the area to the south-west, thins down to 

a mere Shell-tum-Pebble Bed, sometimes only 1 ft. thick. The Osmington 

Oolite Series develops thick masses of detrital Wheatley Limestones, among 

which the coral rag occurs once more in 'separate and irregularly scattered 

patches5 as in the Purton district, and it advances again up the dip-slope to 

cover the plateau to the edge of the escarpment. Finally, the Upper Calcareous 

Grit and Glos Oolites are entirely absent, the Rasenia zones of the 

Kimeridge Clay resting directly upon the Osmington Oolite Series. 

All these considerations point to the action of an elevatory force like that 

which operated in the Purton district, and it is expressed by calling it the 

Oxford Axis. It may perhaps be significant that the area lies upon the 

prolongation of the Sedgley-Lickey Axis (see Chapter III, p. 80). 

The absence of the Upper Calcareous Grit and Glos Oolite Series, such 

conspicuous features on the Dorset coast, called forth some of the earliest 

observations on non-sequential strata, and these invest the Oxford Axis with 

considerable historical interest. 

The junction of the Kimeridge Clay with the underlying coral rag and 

Wheatley Limestones could for upwards of a century be seen in a large quarry 

below the brickyard at the foot of Shotover Hill, but the section has now 

unfortunately become almost entirely overgrown. As early as 1812 W. D. 

Conybeare noticed that, when the Kimeridge Clay was stripped off in this 

quarry, the surface of the stone showed signs of being waterworn and was 

pitted with small cup-shaped depressions. 2 Four years after the publication 

of Conybeare's observation, Sedgwick made the following memorable 

correlation: 

May not the coral rag and superincumbent freestone of Headington Hill together 

represent the central group of the Weymouth and Steeple Ashton sections ? 

The conjecture seems to be confirmed by the appearance of the beds in Headington 

Quarries. In that place the top freestone supports the Kimeridge Clay; and the 

separation between the two is as well-defined as a geometric line. Now the instantaneous 

passage from one formation to another frequently indicates the absence of 

1 For authorities as to thicknesses, and discussion of the possible source of the sand and 

pebbles, see Arkell, 1927, loc. cit., pp. 73-82. 

2 W. D. Conybeare, 1822, in Conybeare and Phillips, Outlines Geol. Engl. and Wales, 

p. 189.

35 45 YDS. 

BERKSHIRE 

XOQUUS 

ILOWE* 

(CALCAR 

I GRIT 

FIG. 70. Section at Magdalen or Workhouse Quarry, Headington, near Oxford, drawn from measurements at 10 yds. 

intervals, showing the different forms of coral rag debris (with the quarrymen's and other names) false dipping from 

the reef. At the base is the horizontal Shell-cum-Pebble Bed, yielding abundantly the Berkshire Oolites fauna. (From 

Arkell, 1927, Phil. Trans. Roy. Soc., vol. ccxvi B, p. 128, fig. 12.)


certain beds or deposits. May not then the upper part of the Weymouth section be 

wanting near Oxford? 1 

In this passage the Wheatley Limestones and equivalent coral rag were for 

the first time correlated with the Osmington Oolite Series, and the true 

position of the Upper Calcareous Grit and Glos Oolite Series ('the upper part 

of the Weymouth section') was evidently realized. Ten years later Buckland 

and De la Beche 2 expressed their agreement with Sedgwick's correlation and 

the ensuing conclusions, and later Phillips also added his confirmation. 

Finally, one hundred years after the appearance of Sedgwick's memoir, the 

widening of the London road near Shotover Lodge afforded Dr. Pringle 

a temporary exposure enabling him to state that the lowest part of the 

Kimeridge Clay is of Rasenia date. 3 The hiatus was thus increased by the 

addition of the Pictonia zone of the Kimeridge Clay to the missing strata. 

The Osmington Oolite Series forms an important surface-feature, 

capping the plateau about Headington and Bullingdon, around the foot of 

the high ridge of Shotover, and similarly encircling the heights of Boar's Hill 

and Cumnor Hurst on the other side of the Thames. Northward, as a number 

of faulted outliers, it caps the hills at Wytham and about Elsfield and Beckley. 

Thanks to a much greater number of exposures than exist in the Purton 

district, the lateral passage from true coral rag to the various types of detrital 

deposits can be followed out in detail. At Headington Quarries, at Wheatley, 

and on the west side of the Thames at Wootton and Sunningwell, immense 

quarries have been worked in the WHEATLEY LIMESTONES. 4 They consist of 

alternate harder and softer bands of the same white detrital material as at 

Purton, usually non-oolitic and composed entirely of finely-ground fragments 

of corals and shells. The harder bands were much worked in the eighteenth 

century as a freestone, to the undoing of some of the colleges in Oxford which 

employed it in their buildings: it has decayed so rapidly that all have had to 

be refaced after less than two centuries. 

The softer bands have in places a curious nodular structure, hitherto unexplained, 

and are known as the Nodular Coralline Rubble. At Wheatley, in 

the weathered face of the old quarries, it is seen to be interbedded with the 

normal Wheatley Limestone, the two types of rock being composed of 

identical materials, differing only in the degree of their subsequent cementation. 

In some of the quarries at Headington tabular masses of coral are 

intercalated in the detrital material, and they gradually increase and coalesce 

towards the reefs, the broken fragments at the same time becoming larger. 

The dip is steeply away from the reefs, and is shown to be only a deposition 

dip by the fact that the series everywhere rests upon the horizontal Shellcum-Pebble 

Bed (fig. 70). 

Failure to comprehend the nature of these deposits, owing to insufficient 

1 A. Sedgwick, 1826, Ann. Phil., vol. xi, p. 350. 

2 1836, Trans. Geol. Soc. [2], vol. iv, p. 25. 


4 First called the Oxford Oolite by Buckland (1818, Table in W. Phillips's Geol. England & 

Wales) where it was said to be worked as a freestone at Headington, and marked as overlying 

the Coral Rag; but in other quarries identical rock underlies coral rag, and the two facies undoubtedly 

alternate (see Arkell, 1927, pp. 132-3). Apart from the fact that oolitic structure is 

very rare, it seems undesirable to retain in its original restricted sense a term that has been so 

widely used with very different meanings (see above, p. 7). Buckman called the Wheatley 

Limestones Holton Beds (T.A., vol. v, p. 53).


field-work, led Buckman a few years before his death to subdivide them into 

several zones. His misunderstanding of the deposition-dip is shown by a 

statement concerning the principal quarry at Headington (Magdalen Quarry, 

fig. 70) that 'there is a non-sequence—stratal failure—of about 6 feet in the 

face of the pit on the E. as compared with the W. 5. 1 In reality such an inference 

is no more justifiable from these beds than from the Forest Marble 

or the Triassic sandstones, or any other formation in which false-bedding is 

manifested on a large scale. The true meaning of the false dip was explained 

by Blake and Hudleston in 1877. 2 

Unbroken fossils are rare, but occasionally they include ammonites, the 

most frequent being Perisphinctes antecedens Salf., though in the Lye Hill 

Quarry, near Wheatley, some badly-preserved giants of the P. parandieri 

style, like forms in the Berkshire Oolites, are found. Doubtless these floated 

in from outside the coralline area. Some of the echinoderms, such as Nucleolites 

scutatus and Pygaster semisulcatus, lived among the accumulating debris, for 

their tests are found perfectly preserved in thin argillaceous seams, although 

all the shells, with the exception of Exogyra nana, are finely comminuted. 

South of Oxford, in the Thames Valley about Littlemore, Sandford and 

Kennington, the Osmington Oolite Series takes on the facies of the LITTLE- 

MORE CLAY BEDS, of which this is the type-locality. The clay facies is well 

displayed in the railway-cutting at Littlemore, consisting of 20 bands of clay 

separated by as many of nodular, grey, white-weathering argillaceous limestone, 

the thickness seen being about 17 ft. (fig. 71). A few small fragmentary 

and crumbly casts of Perisphinctids have been found, but they do not suffice 

for specific identification and appear to be the young of common antecedenslike 

forms. 3 The other fossils are of common, undiagnostic, Osmington and 

Berkshire Oolite species, the commonest being Exogyra nana, massed 

together with Serpulce in the form of shoal-like banks which interrupt the 

otherwise regular bedding. In their lithic and palaeontological characters the 

beds in every way resemble those at Hilmarton. 

Mr. E. S. Cobbold first suggested that the lateral passage of the coral rag 

into the Littlemore Clay Beds might best be explained by supposing that the 

muddy waters of a river or stream flowing from the London landmass here 

found their way through a channel between the reefs to the open sea. 4 This 

suggestion best fulfils all the conditions, for mud is well known to inhibit 

coral growth, and the area occupied by the argillaceous beds is always 

narrow. 5 Moreover, it receives confirmation from a quarry on the side of the 

Thames Valley near North Hinksey; this seems to show us a deposit formed 

on the edge of the mud-bearing currents, for it comprises about 10 ft. of 

impure clay with an admixture of rubbly limestone, enclosing huge disconnected 

blocks of Isastraean and Thamnastraean corals, all of them encrusted 

with Serpulce and Exogyrce. 6 The section is unique and when freshly worked 

it suggests very forcibly a reef that has been continually smothered by pollution 

of the water with muddy sediment. 


2 Blake and Hudleston, 1877, loc. cit., p. 311, and see Arkell, 1927, loc. cit., pp. 122-8. 

3 For Buckman's identification of these and criticism, see Arkell, 1927, loc. cit., p. 143. 

4 E. S. Cobbold, 1880, Q.J.G.Svol. xxxvi, p. 319. 

5 Here the width cannot be more than two miles, and at the other occurrences it is probably 

less. 



The breaking down of the hard limestones into soft clays has enabled the 

modern drainage to find an easy passage through the Corallian ridge; and so, 

if Mr. Cobbold's suggestion is correct, as seems probable, the Jurassic river 

has here determined the course of the Thames. 

OSMINGTON 

OOLITE 

SERIES 

(EQUIVALENTS' 

OF CORAL RAG) 

BERKSHIRE 

OOLITES 

LOWER 

CALCAR. 

GRIT 

SANDY 

LIMESTONE 

LITTLEMORE 

CLAY 

BEDS 

4, 

- 3 

2 

- ! 

-- 0 

SANDY MARLS 

AND 

BRASHY LIMEST. 

SHELL-PEBBLE 

BED 

INDURATED TCP 

FIG. 71. The type-section of the Littlemore Clay Beds (which pass 

laterally into coral rag) at Littlemore railway-cutting, near Oxford. 

(From Arkell, 1927, Phil, Trans., vol. ccxvi B, p. 141, fig. 14.) 

The Berkshire Oolite Series, as has been stated, grows much thinner 

as it approaches the Thames south of Oxford, while the various subdivisions 

so clearly differentiated for 20 miles to the west are no longer recognizable. 

It has already been remarked that the sections at Cumnor, Cothill and 

Marcham show that before its disappearance under the Kimeridge Clay of 

the Boar's Hill ridge the Berkshire Oolite Series becomes highly charged 

with sand. On the beds emerging upon the other side, the same feature is


conspicuous in the more southerly of the sections, at Bagley Wood, Littlemore, 

Cowley and Horsepath. At these places the series consists of some 

5-7 ft. of shelly sand and sandy, shelly limestone, variously interbedded, and 

at the base is the ubiquitous Pebble Bed. The sandy layers contain perfectly-preserved 

shells of Pseudomonotis ovalis, Chlamys fibrosa, Oxytoma 

expansa, Exogyra nana, &c. The harder bands are often shell-beds, crowded 

with the common lamellibranchs and ammonites of the Trigonia hudlestoni 

Limestones. 

Owing to the high proportion of sand in all the strata below the coral rag in 

these sections it is often difficult to draw the boundary-line between the 

Berkshire Oolite Series and the Lower Calcareous Grit. Generally, however, 

the Pebble Bed provides the required datum. 

It has been suggested that the continued influx of sand into the district 

south of Oxford may be explained as due to a survival of the activity of the 

river that brought down the Lower Calcareous Grit. Perhaps it was the same 

river that, when nearing the completion of its cycle, introduced into the 

district the mud to form the Littlemore Clay Beds. 

Towards the north and east, in a short distance, all the quarries about 

Headington, and also those on the other side of the Thames at North Hinksey, 

show that the Berkshire Oolite Series has once more been reduced to the 

Shell-cum-Pebble Bed, only 1-2 ft. thick (see fig. 70). It is a bluish-grey, 

tough, oolitic limestone, locally dark-centred, largely made up of fossils. 

Like the shell-beds of the Inferior Oolite, it is the repository of a rich and 

varied fauna and undoubtedly owes its formation to gradual accumulation on 

a bottom kept free of sediment by currents. The large and fragile valves 

(often 4-5 in. in length) of Limay Chlamys, Trigonia, Gervillia, &c. are generally 

unworn and unbroken, a condition in which they would never have 

survived had they been subjected to wave-action on a beach or to re-derivation 

from one deposit to another. The ammonites belong to a score or more of 

species of the genera Perisphinctes, Aspidoceras and Cardioceras, and include 

many giants of the parandieri and cloroolithicus types. Most of them can be 

matched among the ammonites of the Trigonia hudlestoni Limestones of 

Highworth and Kingston Bagpuize, but there are also new elements. Buckman 

formerly identified them with the species of foreign authors, such as 

Siemiradski and de Riaz, 1 but more recently he had begun to give them all 

new names and to found for them new genera based on differences of detail 

in the septal sutures. A revision of this rich ammonite assemblage still 

remains to be undertaken. A start has been made by Dr. Spath, who places 

most of the species either in Perisphinctes sensu stricto (as represented by P. 

martelli and its allies), or in the closely allied Dichotomosphinctes (the antecedens-plicatilis 

group), and affirms that most of Buckman's genera may be 

ignored. 2 

The Lower Calcareous Grit is composed, as usual, of a mass of yellow 

sands having all the characters of a sandbank, irregularly piled by currents. 

The thickness varies from a maximum of about 50 ft. to 12 ft. (or possibly 

less) in short distances. Except for the uppermost layers, which are seen in 

1 A case full, arranged and named by Buckman, is exhibited in the Oxford University 

Museum. 

2 L. F. Spath, 1931, Pal. Indica% N.S., vol. ix, pp. 401-2.

CORALLIAN BEDS: OXFORD TO THE FENS 409 

the bottom of nearly all the quarries and are worked at Littlemore for a 

moulding-sand to a depth of 15 ft., they are palaeontologically a terra incognita. 

As elsewhere, the highest 1-2 ft. is often indurated, and has the 

Pebble Bed cemented firmly to it. Pachyteuthis abbreviatus and casts of Cardioceras 

cordatum are sometimes found, but most of the ammonites recorded 

from the Lower Calcareous Grit of Cowley and Horsepath by Buckman and 

others came in reality from the sandy facies of the Berkshire Oolite Series. 

The immense hemeral table put forward by Buckman for these beds is purely 

fictitious. 1 

III. THE AMPTHILL CLAY REGION 

(a) Oxford to the Fens 

Five miles east of Oxford, close to the great limestone quarries of Wheatley 

and Lye Hill, the Corallian formation seems to come abruptly to an end. 

Looking eastward one beholds a broad clay vale, and on consulting the Survey 

maps (even the latest colour-printed edition) it appears that with the exception 

of a diminishing outcrop of Corallian Beds from Wheatley to Quainton 

(12 miles) and a small patch at Upware near Cambridge, the Oxford and 

Kimeridge Clays are in contact from here to the Yorkshire Basin. 

The Upware patch represents an isolated reef, which will be described in 

the next subsection. The intervening area has received considerable attention 

in the past forty years from the late Thomas Roberts, Mr. C. B. Wedd, and 

Prof. A. Morley Davies, who have shown that except for a stretch of 30 miles 

north-east of Leighton Buzzard where the Low rer Greensand oversteps on to 

the Oxford Clay, there is a continuous outcrop of beds of Corallian age; but 

they are developed in an entirely different facies. 

The most complete section in this area was a railway-cutting at Ampthill, 

Bedfordshire (long since overgrown), where the Corallian Beds had a total 

thickness of 61 ft. After this exposure, and on account of their predominantly 

argillaceous facies, Seeley called the beds the AMPTHILL CLAY. 2 

The name Ampthill Clay has been commonly used by Woodward and 

others for the whole of the equivalents of the Corallian, but more recently it 

has been found necessary to exclude a basal portion, 6-20 ft. thick, which 

contains oolitic limestone and marl, often ironshot, with derived fossils and 

a great many oysters and Serpulce and other shells. This basal division, called 

the Oakley Clay, or better OAKLEY BEDS, in Oxon. and Bucks., and ELSWORTH 

ROCK or Elsworth Rock Series about Cambridge, is the equivalent of the 

'Upper Corallian' of the Oxford district (the Berkshire and Osmington Oolite 

Series or martelli and antecedens zone). From this it follows that the true 

Ampthill Clay as restricted is younger than any of the Corallian Beds preserved 

on the Oxford Axis or for a considerable distance farther west. 

The Ampthill Clay. 

For our knowledge of the Ampthill Clay we are indebted chiefly to Thomas 

Roberts, who in the latter part of the last century undertook a systematic 

examination of the numerous small clay-pits on the borders of Huntingdon 

1 S. S. Buckman, 1925, T.A., vol. v, pp. 67-8; see Arkell, 1929, 'Mon. Corall. Lamell.\ 

Pal. Soc., p. 7. 

2 He earlier suggested and abandoned first Bluntisham Clay and then Tetworth Clay. See 

bibliography.


and Cambridge. Since many of these pits are now abandoned and are unlikely 

to yield any further information, his careful records are invaluable. 

Roberts showed that the Ampthill Clay can readily be distinguished, both 

lithologically and palaeontologically, from the clays above and below it. It is 

dark and tenaceous, often black, and contains abundant selenite. Wherever 

the junction with the Kimeridge Clay is seen it is marked by a band of 

phosphatic nodules, regarded as the basement-bed of the Kimeridge. The 

fossils differ markedly from those in the Oxford Clay by their state of preservation, 

for they are never pyritized, while the ammonites and some other 

shells in the Oxford Clay are nearly always pyritized; moreover Wedd remarked 

that while the oysters and other shells in the Oxford Clay are freshly 

preserved, those in the Ampthill Clay are generally bored and encrusted, 

both inside and out, with Serpulce. There are several thin bands of limestone, 

usually hard, nodular and argillaceous, never oolitic. 

Roberts described a number of pits from Everton and Gamlingay on the 

Bedfordshire border eastwards along the outcrop at Great Gransden, Elsworth, 

Boxworth, St. Ives and Bluntisham to Fenton, where the clay disappears 

beneath the alluvium of the Fens. Records of Cardiocerates and 

Perisphinctids recur repeatedly; especially 'Ammonites plicatilis' or 'A. 

biplex\ 'A. excavatus\ A. vertebralis' and 'A. cawtonensis\ The 'A. excavatus' 

probably signifies a Prionodoceras (e.g. P. serratum), as also does 

probably 'A. cawtonensis\ while the other names may include Perisphinctes 

and Dichotomoceras. A revision of old material and any new that can be 

collected in existing exposures is needed before detailed correlations can be 

established. Meanwhile, however, it is evident from the presence of Ostrea 

delta that beds as high as the Glos Oolite Series are represented in the 

Ampthill Clay. One of the most fossiliferous horizons described by Roberts 

is a double band of hard, compact, grey limestone, 2-3 ft. thick, called the 

Boxworth Rock. 1 Besides ( A. plicatilis' and 'A. excavatus' this yielded to 

Roberts Trigonia clavellata, Nucula menkei and Alaria bispinosa—three species 

highly suggestive of the Trigonia clavellata Beds. 2 

The type-section at Ampthill was unfortunately never described with the 

care that it would have received had it lain within Roberts's area, and little 

information can now be gained from the record of the cutting. The old lists 

of fossils 3 are useless, for they include the rich fauna of the underlying 

Oakley Beds. This has given rise to an idea that the Ampthill Clay contains 

a mixed Oxford Clay and Kimeridge Clay assemblage. 

A more useful section was described by Prof. Morley Davies in a cutting 

made in 1907 on the Great Western Railway from Princes Risborough to 

Banbury, between Ashendon Junction and Rushbeds Wood Tunnel. 4 Here 

50 ft. of Ampthill Clay was exposed, and also the Oakley Beds below. The 

highest 30 ft. consisted of the usual selenitiferous clay, while the lowest 

20 ft. was more varied, with some thin stone-bands. The highest and thickest 

stone-band, 20 ft. from the base, yielded narrow-whorled fine-ribbed Perisphinctids 

with forward sweep on the periphery, indicating the wartce zone 

1 T. Roberts, 1892,Jurass. Rocks Neighb. Cambridge, p. 43. 

2 Though the identification of the Trigonia needs verifying. 

3 e.g. as given by H. B. Woodward, 1895, J-R-B., p. 137. 

4 A. M. Davies, 1927, in Arkell, loc. cit., p. 152.

CORALLIAN BEDS: AMPTHILL CLAY 411 

and correlating with strata at least no lower than the Trigonia clavellata Beds 

of Dorset. This showed that the bulk of the Ampthill Clay—that portion 

lying above the stone-band (=the Boxworth Rock?)—was to be assigned to 

the upper part of the Glos Oolite Series and Upper Calcareous Grit, or even 

higher beds. The 40 ft. of the Sandsfoot Clay in Dorset, with Ostrea delta, 

affords a suggestive comparison. 

Simultaneously with my publication of this correlation, and independently 

of it, Buckman set down a brief note in Type Ammonites to the effect that 

4 The Ampthill Clay . . . which contains Dichotomoceras variocostatum Buckland 

sp., is not Corallian as usually stated—that is to say, it is later than 

Perisphinctean Age. It is of Prionodoceratan Age—towards the lower part 

of the Kimeridgian as generally understood.' 1 But Buckman apparently had 

not seen the Perisphinctids of wartce style found by Prof. Davies 20 ft. above 

the base of the Ampthill Clay; moreover the necessarily Kimeridgian age 

of the genus Prionodoceras is highly questionable, since P. serratum signalizes 

the decipens zone of Salfeld's classification (= Upper Calcareous Grit, pars) 

and 4Dichotomoceras' variocostatum (Buckland) seems to be a true Perisphinctes 

sensu stricto. But Buckman's suggestion is valuable in so far as it draws 

attention to the fact that the bulk of the Ampthill Clay occupies a higher 

stratigraphical position than was usually supposed. 

The Oakley Beds and Elsworth Rock. 

On the edge of the coralline area, at Stanton St. John, Woodperry and 

Stow T Wood, the Wheatley Limestones are seen, with increasing distance 

from the reefs, to become diluted with marl and clay. A type of rock develops 

which at first sight resembles the Littlemore Clay Beds in its alternation of 

hard and soft bands, but a closer examination reveals that it is largely composed 

of detrital materials and small oysters {Exogyra nana). This interesting 

change did not escape Blake and Hudleston. They described a quarry behind 

the school at Stanton St. John as 'a very remarkable quarry . . . composed of 

alternate layers of hard doggery bands and marl ... a perfect nest of echinoderms.' 

'We see here', they wrote, 'the spot where the corals did not grow, 

as 2t Headington we saw where they did. Here we have the debris of the 

ground-up, variably hardened reef, along with the echinoderms that lived in 

the neighbourhood; and we thus have a natural termination of the Coral Rag 

in this direction.' 2 

An argillaceous deposit crowded with the shells of Exogyra nana was long 

ago mapped by the Survey across the country east of Stanton St. John and 

Wheatley, towards Quainton, but no good sections were known before the 

making of the railway-cutting near Ashendon Junction. Below the true 

Ampthill Clay in that cutting Prof. Davies found 6-10 ft. of beds full of 

Exogyra nana, varying in lithological composition from bluish clay to white 

limestone and marls, full of brown ooliths, like the Elsworth Rock (presently 

to be described) but unconsolidated. They contained also some masses of 

Serpulce and oysters suggestive of the Elsworth Rock of Gamlingay and other 

places in Cambridgeshire. Prof. Davies remarked that the abundance of 

Exogyra nana and Cidaris spines linked these beds with the 'Upper Corallian' 

1 S. S. Buckman, 1927, T.A., vol. vi, p. 49; compare Arkell, 1927, loc. cit., p. 153. 

2 Blake and Hudleston, 1877, Q.J.G.S., vol. xxxiii, p. 310. 

*-">4:i71 F f


around Oxford (the Osmington Oolite Series). 1 The recognition in his 

collection of Chlamys nattheimensis, a mollusc of the coral fauna, seldom if 

ever found dissociated from corals, indicated that reefs were not, in fact, far 

distant. 2 But among the fossils collected by Prof. Davies from the Exogyra 

nana Beds, or as Buckman called them, Oakley Clay, 3 there are also some 

fragmentary Perisphinctids identical with specimens from the Shell-cum- 

Pebble Bed of the Oxford district. The Berkshire Oolite Series, therefore, 

is also represented. 

Prof. Davies determined that in the Ashendon cutting the Oakley Beds 

rest directly upon the upper prcecordatum zone of the Oxford Clay. In the 

8 miles from the edge of the escarpment at Stanton St. John, therefore, the 

Lower Calcareous Grit has been entirely overstepped. He further proved 

that this overstep continues and increases towards the north-east, for he 

recognized the Oakley Beds at Quainton apparently resting on the lower 

prcecordatum zone, and farther still, at Sandy, upon the renggeri or lamberti 

zone 4 (fig. 62,p. 348). A source is thus provided for the great spread of Oxford 

Clay pebbles, 40 miles in length, comprising the Pebble Bed; especially if we 

suppose a similar overstep to have taken place towards the south-east or 

south. 

The recognition of the Oakley Beds as far away as Sandy, beyond Ampthill, 

brings into line the basal beds with many fossils in the Ampthill cutting, 

described by Woodward as a 'rubbly rock-bed like the basement-bed at Gamlingay 

5. 5 It also leads to the threshold of another area, where the deposits 

have been studied independently by Cambridge geologists—the area of the 

Elsworth and St. Ives Rock. 

The basement-beds of the Corallian in Huntingdon and Cambridgeshire 

consist everywhere of some 10-15 ft. of highly fossiliferous strata known as 

the Elsworth Rock or Elsworth Rock Series; and, as in Buckinghamshire and 

Bedfordshire, they rest directly upon the Upper Oxford Clay. The beds 

consist of two rock-bands, the lower 3-7 ft. and the upper ft. thick, 

separated by about 5 ft. of clay. The rock composing both bands is, when 

fresh, a hard, grey, ironshot, shelly limestone, but it weathers readily to 

a yellowish-brown colour and disintegrates to a yellow, calcareous marl, full 

of dark-brown ooliths. The upper band is usually more decomposed than 

the lower, but otherwise they appear to be identical, lithologically and 

palaeontologically. 

Mr. C. B. Wedd mapped the outcrop continuously for about 5 miles from 

Houghton Hall eastwards, past St. Ives to Holywell. On the south side of the 

Ouse Valley he mapped it again for over 6 miles past Elsworth to beyond 

Croxton, thus establishing what Roberts contended on palaeontological 

grounds, that the Elsworth Rock and St. Ives Rock are one and the same 

stratum. 6 As Croxton lies only 7 miles from Sandy, where Prof. Davies 

recognized the Oakley Beds, and as both Prof. Davies at Ashendon and 

Woodward at Ampthill likened the Oakley Beds to the Elsworth Rock, there 

cannot be much doubt that the two are in stratigraphical continuity— 

1 A. M. Davies, 1916, Geol. Mag., vol. liii, p. 398. 

2 W. J. Arkell, 1927, loc. cit., p. 153. 3 1927, T.A., vol. vi, p. 49. 



6 C. B. Wedd, 1901, Q.J.G.S., vol. lvii, pp. 73-85.

CORALLIAN BEDS: ELSWORTH ROCK 413 

though it does not follow that they are necessarily of precisely the same age 

throughout. 

The Sedgwick Museum, Cambridge, contains a large collection of fossils 

from the Elsworth Rock (the greater number from the lower band) of Elsworth, 

St. Ives, Holywell and other places. The lamellibranchs comprise the 

same assemblage as the Trigonia hudlestoni Beds of the Berkshire Oolite Series, 

with additional species of earlier date. 1 The commonest are such familiar 

forms as Trigonia hudlestoni (resembling those found in Yorkshire more 

closely than the typical Berkshire and Oxfordshire forms), T. reticulata, 

Astarte ovatay Cucullcea contractay Chlamys fibrosa, C. splendens, Camptonectes 

lens, Velata anglicay Oxytoma expansayLima mutabilis, L. subantiquata 

and many more. Earlier elements are Nucula oxfordiana de Lor., Parallelodon 

(Beushausenia) keyserlingii (d'Orb.), Astarte cordati Trautsch. and Pinna 

lanceolata Sow. Since the deposit must be dated by its latest fossils, there 

seems no alternative but to correlate it with the Berkshire Oolite Series. The 

ammonites comprise Perisphinctids of the martelli zone mixed with Cardiocerates 

of the cordatum zone; and there are in addition a number of forms, 

including some Oppelids, not known elsewhere in the British Isles. 

This correlation was already advocated by Mr. Wedd, who wrote in 1901 

that he would place the Elsworth Rock 'on a somewhat higher horizon than 

the Lower Calcareous Grit'. 2 In the discussion which followed the reading 

of Wedd's paper Hudleston remarked that, judging by the fossils, 'it was 

impossible to avoid the conclusion that the rock at Elsworth occupies a very 

low position in the Corallian Series'. H. B. Woodward made the ambiguous 

suggestion that 'the occurrence in the Elsworth Rock of the Lower Corallian 

Ammonites perarmatus and the Upper Corallian A. plicatilis might be taken 

to indicate a local blending of the two zones'—an explanation which seems to 

be certainly the right one, although not in the sense in which Woodward 

doubtless intended it. 

Wedd noted that, all along the outcrop of the Elsworth Rock, even as far 

away as Gamlingay and Upware, there is a hard blue rock crowded with 

Serpulce and Exogyra nana, which he took to indicate slow deposition. 

Further, he observed that the Elsworth Rock abounds in casts of ammonites 

to which, after the complete removal of the shell, Serpulce have attached 

themselves. Thus penecontemporaneous erosion has undoubtedly taken 

place, and the 'blending of the two zones' is explained. Sedimentation may 

have been so slow that no appreciable thickness of rock separated the two 

faunas, which could then become mingled with very little disturbance or reworking 

of the strata. 

Lower Calcareous Grit: The Arngrove Stone. 

In the area between the Corallian escarpment at Stanton St. John and the 

projecting Portlandian spur of Brill and Muswell Hills, before the overstep of 

the Osmington and Berkshire Oolite Series on to the Oxford Clay is complete, 

a thin representative of the Lower Calcareous Grit survives, and has been 

named by Prof. Davies the ARNGROVE STONE. Lapping round the south of 

Otmoor, it forms an escarpment which, although subdued, is noticeable in 

1 W. J. Arkell, 1929, 'Mon. Corall. Lamell.', Pal. Socn p. 11. 

2 C. B. Wedd, 1901, loc. cit., p. 83.

4I4 MIDDLE OOLITES 

an area otherwise composed of clays. The rock, which is worked as a 

'gravel' in some shallow pits near Arngrove, is peculiarly light and absorbent. 

Prof. Davies discovered that the Arngrove Stone is composed of spicules 

of the siliceous sponge, Rhaxella perforata Hinde, thus resembling Rhaxella 

cherts in the Lower Calcareous Grit of Yorkshire. 1 It also resembles the 

chert at Purton except that it lacks the large, scattered, brown ooliths. The 

rest of the fauna is composed of lamellibranchs of Lower Calcareous Grit 

species and small Cardiocerates of cordatum and vertebrate styles. It is a 

much richer assemblage than any 

found in the neighbouring sandbank, 

but it is considered to correspond 

only to the lowest, unexposed, 

portion of the Lower Calcareous 

Grit (see fig. 62, p. 348). 

The outcrop of the Arngrove 

Stone is restricted to an ellipse 

about 7 miles in greatest length 

(SW.-NE.) and miles in width, 

extending from the slopes of the 

hills around Stanton St. John and 

Woodperry to about a mile beyond 

Boarstall (see fig. 72). Prof. Davies 

believes that this corresponds with 

the original area of deposition. 

Down the dip-slope to the southeast 

it was believed by Buckman to 

pass into a white clay, seen in the 

fields about Oakley and noted by 

him at Worminghall in a well. In 

the well the white clay was under- 

FIG. 72. Sketch-map of the outcrop of the Arngrove 

stone, by Prof. A. Morley Davies, 1931. 

(Based on the Oxford Special sheet Geol. Survey 

Map of 1908.) Oxford Clay, white; Arngrove 

Stone, black; later Corallian Beds, dotted. 

lain by a 6-in. band of fossiliferous, 

yellow, marly sandstone, which 

Buckman named the WORMINGHALL 

ROCK, recording from it Cardioceras 

cf. zenaidce, Miticardioceras mite, 

Perisphinctes cf. intercendens, 'immense Gryphcece and numerous lamellibranchs'. 

Beneath were 26\ ft. of blue Oxford Clay 

The base of the Arngrove Stone was also seen by Prof. Davies in a well at 

Studley, but there no fossiliferous representative of the Worminghall Rock 

was found. 

The relations of the deposit to the overlying beds have never been clearly 

exposed and the only place where they could be studied would be on the 

flanks of the hill for a short distance on either side of Stanton St. John. 

Prof. Davies noted a considerable thickness of calcareous sandstone above 

the Arngrove Stone in a road-cutting at Woodperry, 3 but at Stanton Great 

Wood he found indications of a clay occupying the same position. 4 

1 A. M. Davies, 1907, Q.J.G.S., vol. lxiii, pp. 37-43. 


3 A.M.Davies, 1907, Q.J.G,S.t vol.lxiii, p.42. 4 Idem, 1909, P.G.A., vol.xxi,p. 235.

CORALLIAN BEDS: THE UPWARE REEF 415 

(b) The Upware Reef 

At Upware, 10 miles north-east of Cambridge, is a small reef, entirely 

isolated among the Fens and seventy miles from the nearest coral-bearing 

rocks at Wheatley. It rises above the level alluvium as a low hill, 3 miles long 

and less than a mile wide. As it produces the only limestone in the district, 

it has been opened up in two large quarries at the north and south ends of the 

hill, and in addition in several minor excavations. Concerning these openings 

and their interpretation as bearing upon the structure of the hill and the 

succession of the strata, an extensive literature has grown up. The locality 

has naturally always attracted the attention of Cambridge geologists: Sedgwick, 

Seeley, Bonney, Roberts and Keeping each made contributions to the 

stratigraphy. After a full description had been published by Blake and 

Hudleston in 1877 there followed an acrimonious discussion between them 

S N 

FIG. 73. Diagrammatic section through the Corallian Beds on the south side of the hill at 

Upware. The coral rag and oolite facies probably interdigitate more than shown. After P. 

Rigby, in R. H. Rastall, 1909, Geol. in the Field, p. 137, fig. 26 (re-drawn). 

and Bonney; but Blake and Hudleston's palaeontological conclusions were in 

the main upheld by Wedd, who collected much new information and published 

an exhaustive account in 1898. Finally, in 1901 certain remaining 

difficulties were cleared up by Prof. W. G. Fearnsides, by means of a special 

excavation made through the floor of the south pit, and the results were 

published by him in 1904 and summarized in an account by Dr. R. H. Rastall 

in 1909. 1 

A brief description of the rock-succession suffices for present purposes, 

without entering into the history of the various controversies. At the same 

time the opportunity is taken to offer some further suggestions as to the 

correlation of the component strata. 

The highest rock on the hill is a typical coral rag, composed of fine reefbuilding 

corals. It is exposed in the upper part of the north end of the south 

pit to a depth of about 10 ft., dipping gently north into the hill (see fig. 73). 

The rag is chiefly built up of layers of Isastraa explanata and Thamnastrcea 

arachnoidesy with which are associated T. concinna, Montlivaltia dispary 

Stylina tubulifera, and numerous mollusca. It forms a creamy white limestone, 

the crystalline masses of coral alternating with pockets of whole and 

broken shells in an earthy matrix. In some of the beds the shells have been 

1 For the numerous earlier references see the Bibliography; the two principal accounts are by 

C. B. Wedd, 1898, Q.J.G.S., vol. liv, pp. 601-9; and R. H. Rastall, 1909, Geol. in the Field, 

PP-133-8.


dissolved away, leaving hollow moulds and casts. Blake and Hudleston 

wrote that, 'It is not so rubbly as many of the rags are, but compares well in 

some portions with that which occurs in Yorkshire, at North Grimston. It 

has, however, a peculiar creaminess about it that is hard to match elsewhere. 

. .. The irregularity of the bedding is an indication of its reef-like 

character.' 1 

The fauna is remarkable, for, although the typical coral-dwelling assemblage 

is present, it is mingled with a large number of mollusca not usually 

found in any abundance in the coral rag, but more characteristic of the shell 

beds. In addition there are several peculiar species not found at any other 

English locality, or only very rarely in Yorkshire, but described from the 

Continent: these are Isoarca texata Quenst., Isoarca multistriata Stall., Opis 

(Coelopis) arduennensis Buv. and Opis (Trigonopis) virdunensis Buv. 2 The 

absence of Thecosmilia annularis, the commonest coral in the Wilts .-Berks 

Oxon. ridge, is also striking. 

Besides these forms there are two species which are highly significant 

because they are abundant in the Trigonia clavellata Beds of Dorset, but have 

never been found in the long outcrops of the Wilts-Berks-Oxon. ridge, 

where those beds are absent: Mytilus (Arcomytilus) pectinatus Sow. and 

Prorokia problematica (Buv.). 

Below the coral rag, and exposed over the southern three-quarters of the 

south pit, is an oolite, locally loose and pisolitic and very shelly, but becoming 

less fossiliferous towards the bottom. The thickness seen is probably over 

20 ft. The upper portions of this oolite contain most of the shells found in 

the overlying coral rag. The following lamellibranchs are most prominent in 

both: Chlamys nattheimensis, Plicatula weymouthiana, Mytilus ungulatus; and 

also Chlamys intertexta, C. incequicostata, C. fibrosa (rare), Navicula quadrisulcatay 

Velata anglica, Lima rigida, L. Iceviuscula, Trigonia reticulata, Myoconcha 

texta and many others, as well as an unusually rich assemblage of 

echinoderms. The typical Perisphinctes martelli also occurs. 3 

A trial hole dug through the floor at the south end of the south pit, made 

during Prof. Fearnsides's investigations in 1901, passed through 4 ft. more 

of the oolite (making nearly 30 ft. in all) into a hard band of coral rag. Below 

this it penetrated another 5 ft. of variable rock, composed of a mixture of 

coral and marl, until, at a depth of 9 ft. it struck a hard oolitic rock stained 

with iron, which was considered to be undoubtedly the Elsworth Rock. 4 

The boring was not carried any farther, but a continuation of the sequence 

was seen some years previously during the sinking of a well near the inn at 

Upware, to the south of the quarry, and nearby in another small opening 

recorded by Wedd. Here coral rock rested on ferruginous oolite with corals 

(2 ft. 3 in. thick) taken to be the top of the Elsworth Rock, which was completely 

penetrated in the well. Beneath the band of ironshot oolite were 

9 ft. 9 in. of clay, the lower part full of Exogyra nana, below which again was 

a lower and thicker ironshot rock-band, as at Elsworth, here 4 ft. thick. The 

lower rock-band, which rested directly on Oxford Clay with Cardioceras, 

1 Blake and Hudleston, 1877, Q.J.G.S.y vol. xxxiii, p. 314. 

2 See Arkell, 1929, *Mon. Corall. Lamell.', pp. 11, 47. 

3 Sedgwick Museum. 

4 W. G. Fearnsides, 1904, in Marr and Shipley, Geol. Cambridgeshire, 

1909, loc. cit., p. 136. 

p. 16; and Rastall,

CORALLIAN BEDS: THE FENS AND LINCOLNSHIRE 417 

Peltoceras athleta (?), P. eugenii, and 'Ammonites hecticus\ contained the fauna 

of the Elsworth Rock, the ammonites recorded being C. cordatum, C. vertebrate, 

C. marice and Peltoceras eugenii. 1 If the last two were correctly identified 

they must have been derived, and they would prove that the unconformable 

overstep of the Oxford Clay by the basement-bed of the Corallian, 

as determined by Prof. Davies in Buckinghamshire and Bedfordshire, is 

here still more pronounced and has penetrated down to the athleta zone. 

However this may be, the presence of Cardioceras cordatum and C. vertebrate 

and the absence of the plicatiloid Perisphinctids so abundant, in fact 

preponderant, in the more westerly exposures, suggests that the Elsworth 

Rock may be not an isochronous deposit—that it may here be earlier in date 

than at St. Ives and Elsworth, in spite of the close lithic resemblance. 

The white oolite is again exposed in the north quarry, where the total 

thickness was estimated by Wedd to be 40 ft. or more. The coralline facies of 

the basal portion does not appear here, and the rock is less fossiliferous. 

Blake and Hudleston long ago placed it, purely on palaeontological grounds, 

below the main or topmost coral rag, which was at that time the only rock 

exposed in the south pit. 

The upper, more fossiliferous portion, of the oolite, at any rate of the south 

pit, and the superincumbent coral rag may be regarded as later in date than 

any of the coral rag of Oxon., Berks, and Wilts, excepting only the reef at 

Steeple Ashton (above, p. 390). This conclusion is warranted by the peculiarities 

of its fauna as well as by its general appearance—both features remarked 

on by Blake and Hudleston. It would thus probably be about equivalent to 

the Steeple Ashton coral rag and the Trigonia clavellata Beds of Dorset 

(perhaps including the uppermost or rubbly portion of the Osmington Oolite 

Series and/or a part of the Sandsfoot Clay); and so to the lower part of the 

Ampthill Clay of Ashendon cutting. 

(c) From the Fens to the Market Weighton Axis 

The isolation of the Upware reef with its shallow-water coralline facies has 

long been known from borings at March, Wicken and other places in the 

Fens, which penetrated from Kimeridge Clay into Oxford Clay without 

meeting with any Corallian Beds as developed at Upw Tare. The Survey maps 

show nothing more of the formation south of the Yorkshire Basin, denoting 

again from their colouring that throughout the long county of Lincolnshire 

the Oxford Clay and Kimeridge Clay are in contact. This is entirely misleading, 

however, for Roberts demonstrated in 1889 that the Ampthill Clay 

is continued through a large part of North Lincolnshire, and there is every 

reason to suppose that it extends from Upware at least as far as the Humber 

(see fig. 74, p. 418). 

In common with the Oxford and Kimeridge Clays, the Ampthill Clay 

would seem to diminish in thickness northward along the Lincolnshire outcrop 

as it approaches the Market Weighton Axis. In two borings at Southery, 

in the Fens 14 miles north of the Upware reef and just over the Norfolk 

border, Dr. J. Pringle assigns about 50 ft. of clays to the Ampthill Clay. 2 In 

the lower portion were encountered several thin bands of argillaceous 

1 C. B. Wedd, 1901, loc. cit. 



limestone, but none of them bore any resemblance to the Elsworth Rock. 

Below the lowest band was a small Cardiocerate, suggestive of thz prcecordatum 

zone. In the lower parts of the Ampthill Clay no fossils were found. The 

upper limit was drawn below a bed of clay containing fragments of large 

smooth ammonites identified as probably Pictonice and so indicating the basal 

zone of the Kimeridge Clay. At a level 23 ft. below this in one boring and 

16 ft. below it in the other, specimens 

of Prionodoceras serratum 

(Sow.) were found. 

The work of Roberts was carried 

out in North Lincolnshire, 

between Bardney, on the latitude 

of Lincoln, and Brigg, a distance 

of about 25 miles. 1 By the same 

careful methods as those which he 

had followed in the Cambridge 

district, examining all the small 

brickyards now for the most part 

abandoned, and helped by several 

railway-cuttings, he established 

that a continuous belt of Corallian 

clays could be traced, differing 

both lithologically and palaeontologically 

from those above and 

below (fig. 74). As in the Cambridge 

district, he found that the 

ammonites in the Oxford Clay are 

pyritized, while those in the Ampthill 

Clay are never pyritized; the 

Ampthill Clay, moreover, can be 

readily recognized by its black 

colour and the abundance of sele- 

FIG. 74. Sketch-map of part of Lincolnshire to nite Crystals. 

show the approximate position of the outcrop of the The deepest continuous section 

clays of Corallian date as determined by Roberts. r A 01 J J 

(After T. Roberts, 1889, Q.J.G.S., vol. xlv, p. 546.) of Ampthill Clay recorded was 

one of 17 ft. seen in a brickyard 

west of Hawkstead Hall. Other sections were described at Bardney, South 

and North Kelsey and Wrawby, in the railway-cutting. 

Roberts found that the black selenitiferous clay contained Corallian fossils, 

and out of 23 species he recognized 16 that occur in the Ampthill Clay. The 

ammonites recorded are such typically Corallian names as 'A. cordatus, A. 

vertebralis, A. excavatus, A. cawtonensis, A. plicatilis, A. achilles and A. decipiens\ 

but further material and more detailed identifications would be 

necessary before their significance could be assessed. The records of 'A. 

excavatus' and 4A. cawtonensis 5 may both refer to Prionodoceras. Again there 

appears to be the same admixture of Gryphcea dilatata and Ostrea delta, but 

here Roberts states that G. dilatata is commonest in the lower part of the clay, 

while O. delta is more abundant in the upper part. Alana bispxnosa also 

1 T. Roberts, 1889, Q.J.G.S., vol. xlv, pp. 545-60.

CORALLIAN BEDS: SOUTH YORKSHIRE 419 

appears in the lists, but so do such typical Lower Calcareous Grit and Berkshire 

Oolite fossils as Chlamys fibrosa and Pachyteuthis abbreviata. 

There is thus insufficient evidence for stating which subdivisions of the 

Corallian formation are represented, and it is unknowm how thick the deposits 

may be. On the whole, however, there seems no reason to doubt that the 

bulk of the clay is of the same age as the bulk of the Ampthill Clay between 

Oxford and Cambridge, belonging high in the Corallian Series. No hard 

basement-beds comparable with those that are such a conspicuous feature in 

the more southerly area have been detected, but the junction with the Oxford 

Clay has nowhere been seen. 

IV. THE MARKET WEIGHTON AXIS 

Between the Humber and the Market Weighton Axis evidence of Corallian 

Beds has been recognized only in a well at Melton, near North Ferriby, close 

to the Humber. 1 They are still clays and they must be very thin and imperfect, 

for the total thickness from the base of the Oxford Clay to the top of 

the Kimeridge does not exceed 100 ft. It is probable that as they approach 

the axis they wedge out altogether. 

We have to pass at least six miles to the north of the Market Weighton 

Axis before we find any Upper Jurassic rocks preserved beneath the Chalk, 

and by that time the normal limestone and sandstone facies of the greater part 

of the series has already returned. The transition from the one facies to the 

other, or the thinning out of both against a dividing ridge of older rocks, will 

never be seen by geologists, for over the critical region the overstep of the 

Chalk has obliterated all the evidence. Nevertheless, the country immediately 

to the north holds the key to the region on the axis and enables us to tell what 

becomes of the Corallian Beds as well as if we could see them. 

The first trace of the beds is found above Ley Field, near Garrowby, 

where a small pocket of normal Lower Calcareous Grit has been quarried 

beneath the Chalk. 2 North of this, about Kirby Underdale, there is another 

considerable gap, owing partly to obscuring talus fallen from the Chalk, but 

principally to minor pre-Cretaceous folds, from the summits of which the 

Upper Jurassic rocks were eroded before the Chalk was deposited. In the 

valley of the Gilder Beck, south-east of Acklam, the Chalk rests again on 

Lower Lias, and on the crest of another sharp anticline between Acklam and 

Leavening it reposes on the Estuarine Series. These minor axes recall those 

parallel to and north of the main Mendip Axis, about Keynsham and Radstock. 

Farther north, the Corallian Beds emerge fully from the Cretaceous covering 

and it becomes possible to discern the movements that took place during 

the Corallian period. The rocks are at first very incomplete. They thicken to 

the north and north-west into the Yorkshire Basin, not only by increments to 

every member of the series, but also by the incoming of some new and important 

subdivisions, of which at least one is not met with anywhere in the 

South of England. 

Until almost as far north as Birdsall Kimeridge Clay rests unconformably 

on the Lower Calcareous Grit. The first subdivision to appear beneath it is 

1 P. F, Kendall and H. E. Wroot, 1924, Geol. Yorkshire, p. 332. 

2 To end of subsection based on C. Fox Strangways, 1892, J.R.B.y pp. 300-70.


the Upper Calcareous Grit, with what is probably the upper part of the Glos 

Oolite Series represented by an argillaceous rock, to be described in the next 

section, the North Grimston Cementstone. At Toft House 'a little impure 

limestone with oolitic grains' makes its appearance and thickens rapidly 

towards North Grimston, gradually coming to represent the whole of the 

great limestone divisions of the Yorkshire Corallian. 

Thus the country between the Chalk Wolds and the Derwent gives us 

a fairly accurate idea of what became of the Corallian Beds over the Market 

Weighton Axis along the line of the present outcrop. It is clear that no part 

of the formation except the Lower Calcareous Grit reached so far south as 

the region where the Chalk overstep would have removed it, all the rest of 

the subdivisions having already disappeared, both by diminution in thickness 

—'wedging out'—and by being overlapped by the Kimeridge Clay. 

V. THE YORKSHIRE BASIN 

The thickening of the Corallian Beds, by the incoming of new subdivisions 

and the expansion of the old ones, continues north-westward 

across the Derwent and along the Howardian Hills to beyond the Gilling Gap. 

In the Hambleton Hills and eastward through the Tubular Range to the sea 

the formation attains a grander development than in any other part of the 

British Isles. It wraps around three sides of the Vale of Pickering, its dipslopes 

along the north and west margins rising into flat-topped moorland, 

untamed and heather-covered, and offering as marked a contrast with the 

gentle hills of the Berkshire and Wiltshire range as do the moors of the Lower 

Oolites with their contemporary formations in the South of England. The 

strongest features of all are the lofty escarpments of the Hambleton Hills. 

For a considerable distance these rise above an average height of 1,000 ft., 

built of the hard gritstones of the Lower Calcareous Grit, much thicker and 

more massive than in the South and presenting precipitous faces westward, 

visible from far away over the Vale of Mowbray, like the Northern Pennines 

seen from the Vale of Eden. 

Between the strata containing the fauna of the Berkshire Oolite Series and 

the true Lower Calcareous Grit are developed some 120 ft. of limestones and 

grits,belonging to the upper part of the cordatum zone. These beds, which are 

unknown in the South of England and may be represented in time by the 

gap below the Pebble Bed, are called the Hambleton Oolite Series, or the 

Lower Limestones and Passage Beds. Farther down the dip-slopes, forming 

an inner circle around the Vale of Pickering, follow the Osmington Oolite 

Series and succeeding beds, with a variable representation of the Upper 

Calcareous Grit. Coralline formations are widespread in the Osmington 

Oolites and probably also in the Glos Oolites, on the horizon of the Trigonia 

clavellata Beds. The earliest coral reef in England is found in the Hambleton 

Oolite Series of Hackness. 

To attempt an adequate description of these rocks in any way commensurate 

with their importance and interest would involve extending this 

chapter far beyond its already swollen proportions. No other formation in 

Yorkshire maintains such continuous variety and so rich a fauna, or stimulates 

inquiry with so many exposures, as the Corallian. Its many-sided interest 

has attracted also a disproportionate amount of research, and we have

CORALLIAN BEDS: YORKSHIRE BASIN 421 

exhaustive accounts of the rocks from the stratigrapher's point of view by 

Fox-Strangways and from the palaeontologist's point of view both by 

Hudleston and by Blake and Hudleston jointly. Yet even still a vast amount 

remains to be discovered, as is being proved by the researches of Dr. Vernon 

Wilson. 

It is customary for purposes of description to divide the outcrop into a 

number of sections, each of which would have an importance equal to that 

of one of the earlier sections of this chapter. But in view of the essential continuity 

of the rocks, we will consider the Yorkshire Basin as a whole, confining 

ourselves to a brief summary of the succession, and noting the localities where 

each subdivision is best developed. 

SUMMARY OF THE SUCCESSION AROUND THE YORKSHIRE BASIN 1 

Upper Calcareous Grit + Upper Glos Oolite Series: 80 ft. east of the 

Derwent and perhaps in the Howardian Hills; not more than 45 ft. elsewhere. 

The second subdivision of the Corallian formation to appear beneath the 

Kimeridge Clay on the north side of the Market Weighton Axis (the first 

being the Lower Calcareous Grit) is a thick argillaceous series called the 

NORTH GRIMSTON CEMENTSTONE. It consists of bands of grey argillaceous 

limestone, like Blue Lias and used for making 'Blue Lias Cement', separated 

by and passing down in the lower half of the series into calcareous shales. 

The total thickness locally may exceed 80 ft. 

The Cementstone Series is markedly unconformable with the coral rag and 

underlying oolite, which it overlaps southward on to the Lower Calcareous 

Grit, before being in turn overlapped by the Kimeridge Clay. 2 The wellknown 

quarries near North Grimston show the character of the rock well. 

Fossils are rather scarce and always difficult to extract. The commonest are 

large specimens of Gryphcea dilatata Sow. of several common varieties, 

including var. discoidea Seeley, 3 also Lucina aspera Buv. (abundant in the 

Upper Calcareous Grit) and such undiagnostic forms as Thracia and Goniomya. 

Some ammonites have been found, recorded by Blake and Hudleston 

as 'A biplex-variocostatus' and 'A. cf. alternans and A. cf. serratus' (Prionodoceras 

or Amoeboceras). 

The Cementstone Series crosses the Derwent and probably persists 

throughout the Howardian Hills, but no exposure has been seen for the whole 

length of 15 miles beyond Hildenley (near Malton). At the extreme west end 

of the Howardians, at Snape Hill Quarry, the upper part of the series is seen 

to have become more arenaceous. The total thickness is here still more than 

50 ft. At the top are 5-6 ft. (formerly 10 ft.) of ferruginous sandstone— 

typical Upper Calcareous Grit—overlying 12J—13 ft. of alternating hard, 

1 Based on C. Fox-Strangways (1892, J.R.B., pp. 300-70), W. H. Hudleston (1876-8, 

P.G.A., vol. iv, pp. 353-410, and vol. v, pp. 407-94), and Blake and Hudleston (1877, Q.J.G.S 

vol. xxxiii, pp. 315-91), with alterations to nomenclature and some additions from personal 

observation and the researches of Dr. V. Wilson. See map, fig. 27, p. 138. 

2 Dr. Vernon Wilson informs me that he considers the Cementstone passes gradually up 

into the Kimeridge Clay. 

3 The Gryphcea was given a new name, G. subgibbosa, by Blake and Hudleston, but a number 

which Dr. Wilson has kindly shown me cannot be distinguished from G. dilatata. The 

varieties like var. discoiasa were recorded by authors as Ostrea bullata Sow., the type of which 

came from the Kimeridge Clay. See Arkell, 'Mon. Corall. Lamell.', Part IV, p. 162.


blue-centred sandstones and softer shaly sandstones, then shales and cementstones 

to a thickness of 36 ft., resembling the North Grimston Cementstone 

but darker and harder; the whole resting on coral rag. 1 This section seems 

to show that the upper part of the Cementstone Series alternates with and 

passes laterally into sandstones, which on the north side of the Gilling Gap 

constitute the Upper Calcareous Grit; though it is not improbable that some 

of the sandstone here is younger than any of the beds seen about North 

Grimston. 

The UPPER CALCAREOUS GRIT in its more typical development encircles the 

north-west and north sides of the Vale of Pickering, its outcrop generally in 

contact with the alluvium, or separated from it only by scattered patches of 

Kimeridge Clay. The first good section is seen in the railway-cutting midway 

between Nunnington and Oswaldkirk. Here and all around the west end of 

the Vale, about Helmsley and onward to Kirkby Moorside, the rock is a 

massive blue-hearted sandstone, frequently containing lines of large doggers 

of still harder rock. It is separated from the coral rag by shaly beds which 

are seldom seen, but they have been reported as full of Gryphcea dilatata var. 

discoidea ('Ostrea bullata'). The ammonites recorded from the Upper Calcareous 

Grit include l A. achilles d'Orb.', 'A. decipiens Sow.', l A. berryeri 

Leseur', 'A. serratus Sow.', 'A. alternans von Buch.', and 'A. biplex (small 

interior whorls) 5, all suggestive of the Ringsteadice and associated forms of 

Wilts, and Dorset. This correlation is confirmed by the presence of Chlamys 

midas (d'Orb.), which in Dorset and the South of England abounds in and is 

restricted to the Upper Calcareous Grit. The shales below thus fall into line 

with the Sandsfoot Clay, and so with at least a part of the Ampthill Clay. 

The southward passage of the Upper Calcareous Grit and underlying shales 

into the North Grimston Cementstone strengthens our correlation of the 

Ampthill Clay. 

Excepting traces on the Hackness outlier, the Upper Calcareous Grit is 

not exposed at the surface east of Thornton Dale, 2 miles beyond Pickering. 

Hereabouts it is usually a soft, brownish-red, ferruginous sandstone, locally 

crowded with Lucina aspera, Pseudomonotis ovalis, Chlamys midas, &c. Below 

are shale and a claystone of variable thickness, which in the Pickering quarries 

is called the Throstler. The Upper Calcareous Grit was proved to extend 

underground to the sea, however, for it was penetrated by borings at Irton, 

near Scarborough, and at Filey. The thickness was 45-46J ft., and most of 

the underlying shale seems to have passed into sandstone. 

Osmington Oolite Series (? + Lower Glos Oolite Series) (CORALLINE 

OOLITE AND CORAL RAG, OR UPPER LIMESTONE), average 50-60 ft. 

The Osmington Oolites and probably also some strata contemporaneous 

with the Trigonia clavellata Beds constitute the main mass of the 'Upper 

Corallian' of Yorkshire, usually known as the Coralline Oolite and Coral Rag, 

or Upper Limestone. They comprise a highly variable and complex set of 

strata, the detailed examination of which is beyond the scope of this work. 

The stratigraphy is as usual greatly complicated by coral growth and, as was 

realized by Hudleston, the spreads of coral rag in different places were not 

1 C. Fox-Strangways, 1892, p. 367; revised measurements and description from Dr. 

Wilson, 1931.


all formed at the same time. As a general rule, however, the main mass of 

rag is found at the top of the division, immediately below the shale or clay 

just described, and this gave rise to the introduction of the term 'The Coral 

Rag' as a stratigraphical term, which, as we have seen, is not permissible. 

Below are many variable beds, the commonest and thickest type being white 

oolite. The combination of the white oolite and the coralline facies forcibly 

recalls the Calne district, where the coralline province of Oxon-Berks 

North Wilts, meets the non-coralline white oolite province of Dorset. 

It is highly probable that some of the Yorkshire coral rag is younger than 

the Osmington Oolites and contemporaneous with the Steeple Ashton and 

Upware reefs, which we correlated with the Trigonia clavellata Beds. The 

shelly facies of these beds, so conspicuous in Dorset, seems to be wanting 

entirely in Yorkshire, but locally some of the characteristic shells are found 

in the highest part of the rag: e.g. Mytilus pectinatus, Lopha solitaria, Lima 

spectabilis Contejean (a species of the Lower Kimeridgian about Montbeliard), 

and Opis virdunensis, only known in France and in the late rag of 

Upware. 1 The localities where these fossils were found are all situated 

around Malton, Hildenley and North Grimston, on the south side of the 

basin, where also the series is thicker than elsewhere. 

At North Grimston is the thickest development of coral rag known in the 

British Isles, amounting to 37 ft. Blake and Hudleston called it the North 

Grimston Limestone, and its peculiar characters may be considered to 

justify a separate name. Besides corals and the usual mollusca and Cidaris 

spines, it contains in places many bands of pale flinty chert. The only other 

localities where any considerable quantity of chert seems to be known in the 

coral rag are a quarry beside the road to the south of Helmsley, and at 

Slingsby, Hildenley and East Ness, near Nunnington. 2 Nowhere else, however, 

is there more than half this thickness of coral rag, and it would seem that 

coral growth proceeded here, at the southern edge of the basin, more continuously 

than anywhere farther north. Within a mile or two towards the 

south the entire division disappears against the Market Weighton Axis. This 

suggests that, if the wedging out is even partly original and not due entirely 

to unconformable overstep of the Cementstone, the water may have been 

shallow here for a longer period of time than elsewhere, and we may be seeing 

something of a true fringing reef that grew against the southern margin of 

the basin. 

The strata below the rag are difficult to correlate with certainty with the 

succession in other parts of Yorkshire. Immediately under the rag are 25 ft. 

of drab-coloured, marly oolites with an occasional band of hard limestone 

and corals, called by Blake and Hudleston the MAMILLATED URCHIN SERIES. 

It is crowded with Diplopodia hemisphcerica, Hemicidaris intermedia, Cidaris 

florigemma, C. smithii and Nucleolites scutatus. The Urchin Marls of the 

Wiltshire-Berkshire range are similar, but here the assemblage of urchins is 

much more varied. 

Below the Mamillated Urchin Series Blake and Hudleston described a 

further 30 ft. of oolites, which have been taken to represent the 'Coralline 

1 W. J. Arkell, 1929, 'Mon. Corall. Lamell.\ Pal. Soc., pp. 8, 11. 

2 Information from Dr. Wilson; the only place where chert was previously noted was 

Helmsley, by Blake and Hudleston.


Oolite' below the coral rag of other districts; but if this correlation were 

altogether correct, the thickness of the series here would be little short of 

ioo ft., or nearly twice the thickness elsewhere. It seems probable that some 

of the Lower Limestones are represented, especially as the oolites are said 

to rest directly upon the Passage Beds, which separate the Hambleton Oolite 

Series from the Lower Calcareous Grit. 

At Malton and the neighbouring village of Hildenley, across the Derwent 

Valley, the thickness is still great, and there is the same difficulty about the 

lower beds. The best section is shown by a large quarry at the cross-roads 

on the north side of Malton, exposing 30-40 ft. of rock. At the top is seen 

up to 7 ft. of coral rag, resting upon 13 ft. of white oolites which seem to 

correspond to part of the rag elsewhere, as they have 'a fauna somewhat 

approaching that of the rag'; 'and', observe Blake and Hudleston, 'this may 

partly serve to account for the very mixed character of the fossils which come 

from the Malton district in an undoubtedly oolite matrix'. 1 The more 

typical Coralline Oolites come in below, to the base of the quarry. Blake and 

Hudleston named these last the CHEMNITZIA LIMESTONES, owing to the 

abundance all over the western side of the Yorkshire Basin of Pseudomelania 

[Chemnitzia] heddingtonensis (Sow.). From them came the bulk of the 

wonderfully preserved shells for which Malton was famous. The collections 

of Strickland, Leckenby, Bean and others, which now enrich the museums 

all over the country, were made at a time when the quarries were more 

actively worked than now. They contain many perfect specimens of such 

large shells as Chlamys splendens, C. inter text a, Lima mutabilisy L. Iceviuscula, 

Corbis ampliata (Phil.), C. decussata Buv., C. umbonata Buv. Some of these 

species are not found in any other part of England, while others are known 

elsewhere only very rarely. The common Chlamys qualicosta, however, 

occurs on this horizon and appears to be restricted to it all over England. 

Limestones high in the series, like those immediately under the rag at 

Malton, and containing some fossils more characteristic of the Upper Calcareous 

Grit, such as Lucina aspera, were also described by Blake and 

Hudleston at Hildenley. Here they recorded 'Ammonites variocostatus\ 

More or less typical Osmington Oolite, of the type called 'Chemnitzia' 

Limestone, with 10-15 ft. of coral rag above, is continuous along the Howardian 

Hills past Hovingham and Cawton to Gilling, and again on the opposite 

side of the Coxwold-Gilling Gap in the long spur about Oswaldkirk and 

Nunnington, and so on to the north side of the basin. The total thickness 

of the division hereabouts maintains an average of 50-60 ft., which is the 

same as the thickness of the Osmington Oolite Series in Dorset. The Urchin 

Glypticus hieroglyphicuSy usually rare, but common at Calne, is recorded from 

Wath, near Hovingham. About Oswaldkirk Blake and Hudleston noted 

a finer profusion of corals than at any other point in Yorkshire, especially of 

Montlivaltia dispar and Sty Una tubulifera; and here, too, the spines of the 

sea-urchins are unusually large. 

Along the north side of the basin the outcrop is continuous past Helmsley, 

Kirkby Moorside and Pickering to Thornton Dale, beyond which there is 

a gap of 5-2 miles to the Brompton, Ayton and Seamer district. There are 

fine sections in the sides of Hutton Beck and also in the gorge of the River 



Seven at Sinnington. The best of all are afforded by the extensive quarries 

at Pickering, where the Osmington Oolite is still obtained for a flux in the 

Cleveland ironworks. 

In the country north of Pickering the coral rag dies out locally and gives 

place to flaggy detrital deposits like the Wheatley Limestones. No true rag 

is present in the Pickering quarries, which show the complete succession well 

up into the Upper Calcareous Grit. Instead, the i Chemnitzia > Limestones 

are succeeded by 15 ft. of impure, earthy and flaggy limestones without corals. 

The same type of rock has a considerable extension along the northern outcrop, 

although locally, and more especially in the lower ground towards the 

alluvium, the rag is luxuriantly developed. The actual passage from rag into 

W Theatley Limestone, such as may be seen about Headington and Purton, has 

been described by Fox-Strangways near the valley of the Hutton Beck, 

north-west of Sinnington. In a quarry he describes about 12 ft. of'irregular 

ragged limestone with Cidaris florigemma and branching corals . . . surrounded, 

or nearly surrounded, with these impure flaggy limestones; which, 

as we have suggested, may have been formed from the denudation of the 

purer beds [of coral]'. 1 

The Sinnington Gorge and the quarries at Pickering (fig. 75) show that 

the 'ChemnitzicL Limestones portion of the Osmington Oolite Series is hereabouts 

18-20 ft. thick; below are 13 ft. of variable limestones with shell-beds 

and occasional nests of corals, forming a passage downward into beds that are 

proclaimed by their fauna to belong to the Berkshire Oolite Series. 

The isolated area inland of Scarborough, some 6-7 miles in length, from 

Brompton past East and West Ayton to Seamer, and its continuation in the 

Hackness outlier, contains beds of coral rag which Hudleston believed to 

occupy a lower horizon than the rag on the west and north-west sides of the 

basin. 2 The principal reasons for this opinion were the abundance of certain 

species of mollusca, such as Nerinea visurgis and Astarte subdepressa Blake 

and Hudleston (A. duboisiana auct., non d'Orb.) which are characteristic of 

the base of the Coralline Oolite at Pickering; and the absence of Cidaris 

florigemma, which abounds in the coral rag of all other parts of Yorkshire, but 

is here replaced by C. smithii. Dr. Wilson does not agree with Hudleston, 

however. 

The best clean section at present worked is at the eastern extremity of 

the outcrop, in the Crossgates Quarry, Seamer, which shows 25 ft. of beds. 

At the top are 12 ft. of alternating oolites, Wheatley Limestones and coral 

beds, and below 13 ft. of oolites. At the base of the higher division with 

corals is a 2 ft. band of coral rock crowded with shells, called by Blake and 

Hudleston the Coral-Shell-Bed. They recognized the same bed, or another 

identical with it, on the Hackness outlier at Bell Heads Quarry, Silpho. 

In Forge Valley, the gorge of the Derwent above Ayton, a complete section 

shows about 14 ft. of coral rag resting on about 25 ft. of oolites. In the 

neighbouring Yedmandale the rag is 20 ft. thick. The causes of the variability 

of these beds was made clear by Fox-Strangways in the following passage: 

'Although there may be 20 ft. of coral rag in some of the sections, it is doubtful 

whether it does not thin out altogether in other places; in fact, the coral rag appears 

1 C. Fox-Strangways, 1892, J.R.B.y p. 351. 

2 W. H. Hudleston, 1878, loc. cit., p. 420.


to stand up in irregular lumps or bosses between the oolitic brash and dense pasty 

limestones which were formed around them, in the same manner that coral reefs at 

the present day are surrounded by deposits formed from their own destruction.' 1 

UPPER 

CALCAREOUS 

GRIT 

? SANDSFOOT 

CLAV 

BERKSHIRE l0 - 

OOLITE < 

SERIES 

FERRUGINOUS SANDSTONE WITH 

T ; J . ^ ' I .") ABUNDANT LUCINA ASPERA, 

CHLAMYS MIDAS, ETC. 

SANDY II MARLY SHALES 

BED OF QFCYPH/TA 

CLAYSTONE (THROSTLER) 

FALSE-BEDDED 

DETRITAL LIMESTONE 

IMPURE EARTHY LIMESTONES 

("BLACK POSTS") 

"CHEMNITZIA" LIMESTONES 

(OOLITES) WITH BEDS OF 

PSEUDOMELANIA & NERINEA 

IMPURE OOLITE 

U PISOLITE 

CO R.ALS 

OOLITE WITH SHELL BEDS 

AND 50ME CALCAREOUSGRIT 

CORALS 

SOLID BLOCKS OF CALCAREOUS 

GRIT OR. F RE ESTON E 

MAIN TRiGONlA BED 

TRIGONIA 8ED PERISPHINCTIOS 

SHELL BEDS ABUNDANT 

CALCAREOUS QfUTS 

FIG. 75. Generalized section at Pickering. Based on Blake and Hudleston, 

Q.J.G.S., vol. xxxiii, pp. 334-6, and personal observation, with 

correlation as suggested in the text. 

On the coast, only the very base of the Osmington Oolite is seen at the 

point of Filey Brigg, where it is poorly fossiliferous and is overlain by thick 

Boulder Clay. 

Berkshire Oolite Series (MIDDLE CALCAREOUS GRIT WITH TRIGONIA HUDLE- 

STONI BEDS), average 10-45 ft., maximum 80 ft. 

One of the best datum-lines for correlating the Corallian Beds of Yorkshire 

with those of the South of England is the Trigonia hudlestoni Beds. 

Shell-banks, crowded with this highly characteristic species and with many 

1 C. Fox-Strangways, 1892, J.R.B., p. 346.


of its associates farther south, such as T. reticulata, Cucullcza contracta, Gervillia 

aviculoides, and many others, immediately underlie and inosculate with 

the basal layers of the 'Chemnitzia? Limestones and the w rhite oolites under 

them, which we recognize as the Osmington Oolite Series. 

The Trigonia hudlestoni Beds form part of a predominantly sandy series, 

called the Middle Calcareous Grit, and mapped separately by the Survey. It 

extends continuously along the northern and north-western sides of the basin, 

attaining its greatest development in the north-west, between Helmsley and 

the Coxwold-Gilling Gap at Ampleforth. Its thickness is as much as 80 ft. 

in the banks of the Rye between Helmsley and Rievaulx, and it forms a great 

surface-spread on Wass and Ampleforth Moors, from the Rye to the Coxwold 

valley. 

The clearest sections are in the Pickering Quarries and Hutton Beck, where 

the thickness is about 20-40 ft.; the rock is exposed in Hutton Beck for nearly 

a mile. The greater part of the series consists of poorly-fossiliferous sandstones, 

but locally freestones are developed, and here and there, especially 

towards the top, some of the slabs are studded with Trigonia and other shells, 

forming almost a solid mass. Perisphinctids similar to those in the South are 

abundant, though they still remain to be figured and identified. A start was 

made by Buckman, who refigured the type-specimens of three species named 

by Young and Bird, but unhappily all under redundant new generic names. 1 

There are also Cardiocerates of excavatum type 2 and Aspidocerates (A. 

perarmatum in the old records), just as in the T. hudlestoni Beds in the South 

of England. 

Towards both the east and the south-east the series becomes thinner. On 

the coast it is represented by 6 ft. of alternating shelly beds and sandstones, 

overlying 10 ft. of more massive sandstones, called the Filey Brigg Calcareous 

Grit. In the Howardians it thins down in the same way, until at the eastern 

end, about Malton, it is doubtfully represented by 10 ft. of gritty limestone 

containing large lamellibranchs, formerly exposed at Middle Cave. South of 

Malton it cannot be detected at all. 

In view of the unconformable relations of the Berkshire Oolite Series to 

the beds underneath in so much of the South of England, a quarry described 

by Fox-Strangways on Wass Moor, north-west of Ampleforth, acquires 

a special interest. 3 It showed the base of the Middle Calcareous Grit resting 

on the Hambleton Oolite Series (Lower Limestone), in the top of which 

a large channel had been excavated and filled with sandstone before the grits 

were deposited. Erosion therefore preceded the deposition of the Trigonia 

hudlestoni Beds, at least locally, in Yorkshire also. 

Hambleton Oolite Series (LOWER LIMESTONE AND PASSAGE BEDS), maximum 

90 ft. 

The next beds, the Hambleton Oolites of Blake and Hudleston and the 

Lower Limestone and Passage Beds of the Survey, are altogether peculiar to 

1 Perisphinctes maximus (Young and Bird) (refigured T.A., 1924, pi. DXII), P. ingens (Y. & 

B.) (T.A., 1920, pi. CLXXXIV) and P. pickeringius (Y. & B.) (T.A., 1923, pi. CDXLVIII), all from 

Pickering. 

2 Including i Chalcedoniceras y chalcedonicum (Y. & B.) (T.A., 1922, pi. ccxcv, A & B) from 

Thornton. 

3 C. Fox-Strangways, 1892, J.R.B., p. 341, fig. 17. 

s;,4:ni G g


Yorkshire, where they are, however, of great stratigraphical importance. 

Like the Middle Calcareous Grit, the beds are lenticular in shape, the thickest 

part of the lens being situated over the north-western end of the Vale of 

Pickering, away from which they thin out in all directions. Fox-Strangways 

thought that this distribution was determined by the original circumstances 

of deposition rather than by subsequent erosion, and the same view is taken 

by Dr. Versey. 1 

Over most of the north-eastern part of the area the Survey were able to 

map two distinct subdivisions, the Lower Limestone or Hambleton Oolite 

proper above, and a more gritty series below, called the Passage Beds. The 

two subdivisions grade imperceptibly one into the other, not only vertically, 

but also horizontally. On the coast, at Filey, the whole is developed in the 

gritty facies of Passage Beds, while at the west end of the Vale of Pickering 

all is limestones. 

As remarked above, the lower portion of the great thickness of oolites at 

North Grimston, usually all grouped as 'Upper Limestone', may probably 

represent the Hambleton Oolite Series; the Middle Calcareous Grit, which 

usually separates the two, having wedged out. If this surmise be correct, the 

Hambleton Oolite Series has not such a localized distribution as has been 

supposed. 

The best section of the Hambleton Oolite Series in the Howardian district 

is seen in the Brows Quarry, Malton, now unfortunately abandoned. It still 

shows a mural face of peculiar buff-coloured, fine-grained, gritty, sparselyoolitic 

limestone, from which such early forms as Rhynchonelloidea thurmanni, 

Millericrinus echinatus and Cardiocerates recorded as 'A. cordatum! have been 

obtained. Fossils, however, are always rather scarce in these beds. 

Beyond the Coxwold-Gilling Gap the limestone thickens rapidly, and in 

the country at the west end of the Vale of Pickering and on the dip-slope of 

the Hambletons it has an average thickness of 50-60 ft., with a maximum of 

perhaps 90 ft. between Hawnby and Kepwick. 2 Up the dip-slope, however, 

it thins to 16 ft. on the edge of the western escarpment. In this district the 

rock is poorly fossiliferous and much silicified. In extensive quarries at 

Kepwick Blake and Hudleston recorded Cardioceras cordatum, Rhynchonelloidea 

thurmanni, Oxytoma expansa, Pseudomonotis ovalis, P. Icevis and a few 

other fossils, all of Lower Calcareous Grit aspect. 

'The fact is,' wrote Fox-Strangways, 'in this region the base of the [Lower] 

Limestone [Hambleton Oolite Series] and the top of the Lower Calcareous Grit are 

dovetailed together, producing an alternating series of sandstones and limestones, 

which to the north develop into one thick bed of limestone, while to the south first 

the lower band of limestone dies out and then the upper, so that in the south-east 

of this range of hills there is only one thick mass of arenaceous strata to represent 

the whole of these limestones. ,3 

It is only east of Kirk Dale (north-west of Kirkby Moorside) that the lower 

part of the Hambleton Oolite Series becomes permanently gritty enough to 

map separately as the Passage Beds. Along the rest of the Tabular Range the 

1 H. C. Versey, 1929, Proc. Yorks. Geol. Soc., N.S., vol. xxi, p. 210. 

2 Fox-Strangways stated that the maximum was 80 ft., but Dr. Wilson informs me that at 

least 90 ft. are visible above Arden Hall, near Hawnby. 

3 1892, J.R.B., p. 331.

PLATE XVIII 

Photo. Godfrey Bingley. 

Gristhorpe Cliff, near Filey, Yorks. 

The overhanging bluffs are of Lower Calcareous Grit with some Lower Limestone, 

capped with Boulder Clay; the cliff below is of Oxford Clay. 

Photo. W.J.A. 

The Carr Naze, north side of Filey Brigg. 

Cliffs of Filey Brigg Calcareous Grit, Lower Limestone and Passage Beds, with 

thick covering of Boulder Clay.


two divisions are then well distinguished, the limestones, 30-50 ft. thick, 

above, and the Passage Beds, up to 20 ft. thick or more, below. Above Staindale 

the Passage Beds have been locally cemented by silica, and the hardened 

portions, having resisted the action of the weather, stand up on the moor as 

the famous Bride Stones—some as much as 16 ft. high. 

The two divisions are still distinguishable on the coast in Scarborough 

Castle Hill, where the limestone contains an abundance of very large shells 

of Gervillia aviculoides \ but farther south, at Filey Brigg, they have coalesced, 

leaving some 35 ft. of strata, all in the gritty facies like the Passage Beds, but 

still with the large Gervillice. 

On the Hackness outlier the Hambleton Oolite Series provides evidence of 

the earliest coral growth of the Corallian period in Britain. At the base of 

some 35 ft. of limestone are about 6-8 ft. of typical coral rag, which is best 

seen at Suffield and Silpho, but may extend as far south as Seamer Moor and 

as far west as Bickley or even Thornton Dale. In this early rag was already 

gathered together the well-known assemblage of corals, lsastrcea explanata, 

Thamnastrcea concinna, Thecosmilia annularis and Rhabdophyllia phillipsiy 

with their inevitable molluscan associates, Lithophaga inclusa, Lima zonatay 

Chlamys nattheimensis, Exogyra nana, Lopha gregarea and the ubiquitous 

Cidaris smithii (but not C.florigemma); and in addition a rich fauna of sponges 

and small brachiopods. Immediately above follow oolites with the typical 

giant Gervillia aviculoides, and Cardioceras recorded as C. cordatum. There 

can therefore be no doubt, either on stratigraphical or on palaeontological 

grounds, of the antiquity of this reef—or rather of the reef of which we see 

the broken fragments, with corals that have taken root amongst the debris. 

The only feature at all peculiar is the greater abundance than usual of small 

brachiopods and sponges. Nearly all the Corallian Calcispongiae figured by 

Hinde in his monograph were recorded from here. 

The determination of the stratigraphical position of the Hambleton Oolite 

Series in relation to the Corallian rocks of the South of England presents 

difficulties. The series is evidently to be regarded as a subdivision of the 

cordatum zone, for Cardioceras cordatum has been repeatedly recorded from 

it; and the passage just quoted from Fox-Strangways indicates the manner in 

which the limestone alternates with the normal sandstones of the Lower 

Calcareous Grit. On the other hand, such a development of limestones in the 

cordatum zone is known nowhere else in Britain. Some elements in the shellbed 

fauna also are unique; in particular the highly characteristic Gervillia 

aviculoides of gigantic dimensions, and two species of Trigonia, T. spinifera 

d'Orb. and T. blakei Hudleston. 

It is suggestive that from Calne, in Wiltshire, throughout North Wilts., 

Berks., Oxon., Bucks, and Beds., to at least as far as Upware, Cambridgeshire, 

the Berkshire Oolite Series rests non-sequentially and even unconformably 

upon the underlying cordatum and prcecordatum zones; and that for forty 

miles it has at the base a pebble bed giving incontestable proof of erosion. 

I suggested in 1927 that in the South of England the cordatum zone is 

nowhere complete, and that the Hambleton Oolite Series may represent the 

missing strata. Until some more satisfactory correlation is put forward, it 

seems reasonable to suppose that the Yorkshire beds were laid down during 

the time-interval represented in the South of England by the Pebble Bed,

FL LEY 

BRIGG 

CAYTON OSGODBY 

BAY NAB 

CARR 

NAZE 

HAMBLETON OOLITE SERIES 

WHITE 

NAB 

GRISTHORPE YON'S RED CAYTON 

NAB CLIFF BAY 

SCARBOROUGH CASTLE NORTH 

FIG. 76. Diagrammatic section along the cliffs from Filey to North Bay, Scarborough. Total distance 8 miles. The right-hand 

end of the lower section is separated from the left-hand end of the upper section in fig. 41 by about a mile of cliff composed of 

Boulder Clay. Vertical scale exaggerated. (After J. F. Blake, 1891, P.G.A., vol. xii, p. 116.) (Included to show the general lie of 

the strata; the detail requires revision.) 

BAY

CORALLIAN BEDS: YORKSHIRE BASIN 

Lower Calcareous Grit, 50-150 ft. 

The Lower Calcareous Grit of Yorkshire is officially described as 

'a yellow calcareous sandstone with doggers and cherty-bands passing down into 

softer sandstones, which become more shaly towards the base and gradually pass 

into the sandy shales of the Oxford Clay. Although the term "Grit" is applied to 

this rock, there is very little of it that would be called a grit among older formations, 

in fact many of the sandstones even of the Lower Oolite are harder and firmer and 

far more gritty. ,I 

This description, although perfectly accurate, conjures up a formation 

differing little from the Lower Calcareous Grit of the South of England. But 

in reality the Yorkshire rocks, as may be seen by reference to PI. XVIII, are on 

the whole far harder and more massive, almost devoid of loose sand. The 

strongest bands of blue-hearted or blackish gritstone have few parallels in 

the South, excepting only in the Lower Calcareous Grit of the Weymouth 

district, where, however, the formation is so much thinner that the resemblance 

is not very striking. 

In the Yorkshire Basin the Lower Calcareous Grit, as has been stated, 

is the first part of the Corallian Series to reappear on the north side of 

the Market Weighton Axis. Thence it is the most persistent member of the 

formation all round the basin. It attains its greatest development in the 

Hambleton Hills, where it caps the highest ridge of the escarpment, reaching 

a maximum height of 1,309 ft. above the sea in Black Hambleton. It also has 

a wide outcrop through the Tabular Range, extending as long tongues northward 

along the water-partings between the becks, far into the North York 

Moors. On the coast it is the only portion of the Corallian Series well exposed 

in the cliffs, under Scarborough Castle, in Red Cliff, Cayton Bay, and southward 

from Gristhorpe Cliff to Filey Brigg (fig. 76). Its great hardness and 

resistance to atmospheric weathering are directly responsible for the magnificent 

overhanging ramparts of Red Cliff and the jagged and vertical coast 

fronting the north side of the Carr Naze at Filey—some of the finest coastal 

scenery in Yorkshire. 

Much of the Lower Calcareous Grit in Yorkshire is built up of sponge 

spicules, which are locally so abundant at certain horizons that they give rise 

to beds of chert. The species is Rhaxella perforata Hinde, 2 the same as that 

which builds up a large part of the Arngrove Stone and the similar cherty 

stone of Purton. 

Measurements of the thickness vary greatly, from 60 ft. at the south end 

of the Howardian Hills and on the coast at Filey and Scarborough, to 150 ft. 

along the Tabular Hills and as much as 200 ft. at the north end of the Hambletons. 

It will be evident, however, from what has been said of the Passage 

Beds above and of the Oxford Clay below, that these figures include an 

indefinite amount of both older and younger strata in different places. In the 

Hambleton Hills, about Kepwick, as much as 45 ft. of limestones belonging 

to the Hambleton Oolite Series pass laterally into sandstones, which cannot 

be distinguished from the Lower Calcareous Grit. At Roulston Scar supposed 

Lower Calcareous Grit, resting directly on Hackness Rock, has 

1 C. Fox-Strangways, 1892, J.R.B., p. 304. 

2 G. J. Hinde, 1890, Q.J.G.S., vol. xlvi, pp. 54-61. 

467


yielded a Kosmoceras of the athleta zone (see p. 360). Along most of the 

inland outcrop the boundaries, both above and below, are quite indefinite. 

The coast-sections alone present a clearly-defined Lower Calcareous Grit; 

but even there the collections of the earlier geologists show that at least a 

part of the grit is in the prcecordatum zone of the Upper Oxford Clay. 

C. prcecordatum identical with specimens found at Studley (Plate XXXVII, 

fig. 2) are represented in the old collections, in hard gritstone matrix. 

In the cliffs below Scarborough Castle and from Cayton Bay to Filey Brigg 

the thickness is about 60-70 ft., and three fairly-well-marked divisions may 

be recognized. The highest 10-18 ft. consist of soft sandstone, weathering 

to a sand, with lines of huge, intensely hard doggers like cannon-balls. These 

'Ball Beds' are especially conspicuous in the cliff of Scarborough Castle Hill, 

and some of the smaller balls closely resemble those in the Lower Calcareous 

Grit of Redcliff Point, near Weymouth, which Buckman mistook for derived 

blocks. Inside they sometimes contain nests of fossils, the commonest being 

Chlamys fibrosa, Rhynchonelloidea thurmanni and Pinna lanceolata Sow. (of 

which the type-specimen came from Oliver^ Mount, Scarborough). On the 

platforms north-west of Filey Brigg, large double-valved shells of Trigonia 

triquetra Seebach may also be seen. 

Under the Ball Beds is a 3-7 ft. block of very hard cherty calcareous gritstone, 

which is not only a conspicuous feature along the cliffs, jutting out 

abruptly beyond the softer strata above and below, but also caps many miles 

of the inland escarpment through the Tabular Hills, forming surface-spreads 

wide out of all proportion to its thickness. 

The main mass of the Lower Calcareous Grit below consists of rough 

reddish or yellowish-brown grits and gritstones, with siliceous cement concentrated 

in bands and nodules. The whole weathers with a very irregular 

and jagged surface. 

The fauna of the Lower Calcareous Grit seldom seems rich. Cardioceras and 

Aspidoceras are frequently quoted, but it is now difficult to obtain specimens 

adequate for specific determination. The commonest fossil, besides Chlamys 

fibrosa, is Rhynchonelloidea thurmanni, which is crowded in certain bands. 

It is curious that this Rhynchonellid has been recorded in the South of 

England at only two places—an old quarry at Catcombe, south of Lyneham, 

Wilts., now entirely obscured, 1 and in one of the borings in Kent. 2 

VI. EAST SCOTLAND 

(a) The Brora District of Sutherland 3 

In Scotland the Corallian rocks are unfortunately not continuously exposed 

and little is known of any but the lowest portions. In the coastal plain 

north of Brora, where the bulk of the formation is presumed to occur, there 

are no exposures and much of the ground is covered with raised beach material 

and peat. There is an outlier south of the River Brora, in Dunrobin and 

Uppat Woods, but the surface is densely wooded and largely obscured by 

Drift (map, fig. 63, p. 366). 

Where the low cliffs begin near Kintradwell, 2 miles north of Brora, 


2 See p. 439. 

3 Based on G. W. Lee, 1925, 'Geol. Golspie*, Mem. Geol. Surv.> pp. 95-9, and personal 

observations.

CORALLIAN BEDS: EASTERN SCOTLAND 433 

Kimeridge Clay has already come in, but still farther north a gentle anticline 

near Loth brings up a series of sandstones which certainly belong mainly to 

the base of the Kimeridge formation, but may also in part represent the 

highest beds of the Corallian. Their position has been debated by several 

geologists. H. B. Woodward originally mapped them as Upper Corallian, 

but G. W. Lee considered them to be Kimeridgian and his conclusion was 

supported by Buckman tentatively identifying ammonites in Lee's collection 

as Rasenia and Pictonia. More recently, Dr. J. Pringle and Dr. M. Macgregor 

1 have found between tide-marks a fossiliferous ledge which was 

previously overlooked, and from this they have collected a lamellibranch 

fauna (still unpublished) which they consider to have more affinities with the 

Corallian than with the Kimeridge Clay. This ledge lies off the mouth of 

a stream know Tn as Allt na Cuile, about 1 mile south-west of Loth Railway 

Station, and it is only visible at low tide. Hitherto it is the only known exposure 

of beds that may represent the higher part of the Corallian formation. 

The Lower Calcareous Grit is better known, from several exposures, but 

although the fauna is fairly abundant near the top, the downward limit 

within the Brora Sandstone (see p. 367) is purely a matter of conjecture. 

The best exposure of the Lower Calcareous Grit in Sutherlandshire is at 

Ardassie Point, near the golf links, on the north side of the mouth of Brora 

River. No cliff-section exists, and a geologist first arriving there at high tide 

is disappointed to see only blown sand. The rocks emerge at low tide as 

several ledges running out to sea. They consist of seven bands of hard dark 

limestone separated by beds of carbonaceous shaly sandstone, the whole 

known as the ARDASSIE LIMESTONES. A total thickness of about 16 ft. is 

exposed. When the rock is broken up with a heavy hammer it is found to be 

highly fossiliferous, the most conspicuous members of the fauna being Cardiocerates 

and lamellibranchs. The Survey have recorded Cardioceras cf. cordatum 

(three forms), C. cf. cawtonense, C. cf. excavatum, C. cf. maltonense, C. cf. 

rouilleri, C. cf. suessi, and six unnamed forms, one figured by Buckman as 1 Scoticardioceras' 

scoticum ; 2 also Klematosphinctes vernoni (?), a Perisphinctid of biplex 

type, and numerous lamellibranchs. The lamellibranchs belong almost entirely 

to common Corallian species, such as Chlamys splendens, C. fibrosa, 

Camptonectes giganteus, Lima mutabilis, Oxytoma expansa, &c., but there are 

a few unfamiliar elements, especially an abundant small Grammatodon. 

The Ardassie Limestones strike inland in a westerly direction, and from the 

fossils found in surface rubble they are believed to cap Braambury Hill (see 

map, p. 366). 

Another fossiliferous section in the Lower Calcareous Grit is afforded by 

a small road-metal quarry 320 yards south-west of Uppat House, on the 

wooded outlier south of the Brora River. About 8 ft. of sandstone are exposed, 

from which numerous impressions of more or less flattened Cardiocerates may 

be obtained, together with moulds of typical Corallian lamellibranchs. The 

bed is distinguished as the UPPAT CARDIOCERAS BED, and both by its fossils 

and by their state of preservation, it bears rather a striking resemblance to 

the Arngrove Stone. Among the many species common to the two is a small 

clavellate Trigonia. 

The species of Cardioceras, of which the Survey record eight, are the 

1 1930, P.G.A , vol. xli, p. 81. 2 T.A. 1925, pi. DXCIX.


same as those in the Ardassie Limestones, and the two deposits cannot be 

of very different dates. The lamellibranchs constitute a poorer assemblage, 

however, and the lithology is quite different. Lee considered that the Uppat 

Cardioceras Bed was probably rather earlier in date of formation, and suggested 

that it might lie on the horizon of a fossil bed in the upper part of the 

Brora Sandstone east of the bridges at Brora, mentioned by Judd but no 

longer open to view. 

The absence of fossils in the bulk of the Brora Sandstone, below these 

Cardioceras horizons, precludes the drawing of any boundary line between 

the Lower Calcareous Grit and the Oxford Clay. The sandstone was described 

in the previous chapter because it forms a part of the Brora Arenaceous 

Series, of which the lower divisions are certainly of the age of the Oxford 

Clay; but the upper portions of the Brora Sandstone in the restricted sense 

are just as likely to correspond with some of the little-known basal portion 

of the English Lower Calcareous Grit. 

A feature of the Sutherland Lower Calcareous Grit which should be 

mentioned is the lack of exact agreement between the ammonite species and 

their English prototypes. 'Ardassie', wrote Buckman, 'reveals little correspondence 

with the fauna of the Yorkshire beds. Its species, with few exceptions, 

appear to be new to English strata, but they have a likeness to Russian 

forms figured by Ilovai'sky.' 1 


At Port-an-Righ, Ross-shire, both of the shore-sections between tidemarks, 

already referred to in connexion with the Oxford Clay (above, p. 369), 

are continued up into Corallian Beds, and they show (although obscurely) 

strata higher in the sequence than any that can be definitely ascribed to the 

Corallian in Sutherland. The northern section shows the highest beds, those 

near the top in the southern (Cadh-an-Righ) locality being nearly vertical 

and unfavourably displayed for fossil-collecting. 

The highest Jurassic rocks seen are the PORT-AN-RIGH SANDSTONE, about 

60 ft. of dark, shaly-weathering sandstones, with some hard bands and 

occasional small doggers. Fossils are sparsely distributed, but the Survey 

succeeded in collecting, besides a few indeterminative lamellibranchs and 

a Cardiocerate, three highly important Perisphinctids. Buckman identified 

them as Perisphinctes antecedens, P. martelli ('cf. biplex') and P. cf. stenocycloides 

(Neum.), 3 which indicate a date at least as late as the Berkshire 

Oolite Series. 

The beds in which the Cardioceras cordatum fauna has been found consist 

of 7 ft. of soft, dark sandstone with nodules and nodular ribs of ironstone, 

called by Buckman the PORT-AN-RIGH IRONSTONES. From them the Survey 

collected the true Cardioceras cordatum (Sow.), C. excavatum (Sow.), and three 

other Cardiocerates, with another ammonite referred tentatively to Klematosphinctes 

vernoni (Bean-Phil.). Below are the thick shales of the prcecordatum 

zone of the Oxford Clay. It is not justifiable to assume, however, that the 

Lower Calcareous Grit is reduced to 7 ft. in thickness, for it may also include 

an indefinite quantity of the Port-an-Righ Sandstones, below the level (not 

stated) at which the Perisphinctids were found. 

1 S. S. Buckman, 1925, T.A., vol. v, p. 49. 2 G. W. Lee, 1925, loc. cit., pp. 100-3. 

3 S. S. Buckman, 1925, T.A., vol. v, p. 49.

CORALLIAN BEDS: HEBRIDES 435 

VII. THE HEBRIDEAN AREA 1 

The impossibility of drawing a definite boundary between the equivalents 

of the southern Lower Calcareous Grit and Oxford Clay within the Cardioceratan 

deposits is as manifest in the Inner Hebrides as in Sutherland. The 

cordatum fauna of the Lower Calcareous Grit occurs in three places, in the 

promontories of Strathaird and Trotternish, Skye, and in the Isle of Eigg. 

In Strathaird it is succeeded by an assemblage of Perisphinctids correlating 

with the Berkshire Oolite Series, and the beds containing these are overlain 

unconformably by Upper Cretaceous sediments and Tertiary basalts; in 

Trotternish, however, a complete sequence of Corallian and Lower Kimeridgian 

shales may be expected, even though not fully exposed. 2 Sufficient 

detailed collecting has not yet been undertaken to show where the prcecordatum 

fauna of the Upper Oxford Clay gives place to the true cordatum and 

excavatum fauna of the Lower Calcareous Grit, and the Survey have found 

it impracticable to separate the equivalents of the two formations, either on 

their maps or in their descriptive memoirs. 

The Skye and Eigg occurrences were described in the previous chapter in 

connexion with the Oxford Clay (p.371). In Strathaird, Skye, the beds usually 

called Oxford Clay, which consist of some 200 ft. or more of dark sandy or 

micaceous shales, passing down into 80 ft. of sandstones, occur in a syncline 

running along the centre of the promontory. Owing to the overstep of the 

basalts across the syncline the highest sedimentary horizons preserved come 

to the surface along the sides of the central valley of Abhuinn Cille Mhaire. 

Here Wedd found a number of ammonites of obvious Berkshire Oolite 

affinities, identified as Perisphinctes ? variocostatus (Buckl.), P. ? pickeringius 

(Y. & B.), }P.suevicus Siem., P. ? mogosensis Choffat, and Cardioceras cf. 

quadratum (Sow.). 

At lower levels, in the cliff's north of Elgol, a Cardioceras fauna similar to 

that of the Ardassie Limestones and the Uppat Cardioceras Bed is said to 

occur to the base of the series. The forms recorded by Messrs. Wedd and 

Kitchin are as follows: Cardioceras cordatum (Sow.), C. cordatum (d'Orb.) 

pars, C. ex cavatum (Sow.), C. ? funiferum (Phil.), C.? nikitinianum Lahusen, 

C. quadratoides (Nikitin), C.? quadratum (Sow.), C. cf. rotundatum (Nikitin), 

C. rouilleri Lahusen, C. suessi Siem., C. tenuicostatum (Nikitin), C. vertebrate 

(Nikitin): an assemblage which appears to be a mixture of forms of the 

cordatum and prcecordatum zones. 

At Laig Bay in the Isle of Eigg, in a section exposed on the foreshore at low 

tide, described in the preceding chapter with the Oxford Clay (p. 372), a 

definite Lower Calcareous Grit fauna occurs in the dark-grey shales of 

Oxford Clay facies. Here Barrow found Cardioceras cordatum (two forms, 

coarsely and finely ribbed), C. excavatum and Aspidoceras perarmatum, 

associated with some typical Corallian lamellibranchs, the assemblage being 

very much the same as that of the Ardassie Limestones. No higher strata 

comparable with the Perisphinctes beds of Strathaird appear to be exposed. 

An indication of the highest ammonite horizons of the Corallian (Upper 

1 Based on C. B. Wedd, 1910, 'Geol. Glenelg, Lochalsh and S.E. Skye', pp. 128-31; and 

G. Barrow, 1908, 'Geol. Small Isles of Inverness', pp. 26-8; Mems. Geol. Surv. 

2 See Mr. M. MacGregor's find of Lower Kimeridge Clay at Kildorais, NW. of Staffin, 

mentioned in the next chapter, p. 478.


Calcareous Grit), with Prionodoceras and Dichotomoceras, has recently been 

found in North Trotternish, Skye, by Mr. Malcolm MacGregor. The downward 

relations of the beds have not been seen, but upward they are continuous 

with a series of shales containing Pictonia and Rasenia, and so the 

occurrence is described in Chapter XIV, in connexion with the Kimeridge 

Clay (p. 478). 

VIII. KENT 1 

The concealed province of Corallian rocks beneath the Weald is one of the 

most important in Britain. In it there is an exceptionally thick development 

of the upper divisions—Upper Calcareous Grit, Glos Oolite and Osmington 

Oolite Series. The lower divisions, the Berkshire Oolite Series and the 

Lower Calcareous Grit, on the other hand, are poorly developed and it is 

difficult to bring them into line with the thick Dorset sequence. This part of 

the succession is more comparable with the Lower Corallian Beds on the 

north of the Paris Basin, in Normandy and the Boulonnais, than with those of 

any other English district. 

The complete succession was penetrated in four borings at Dover, at 

Brabourne, 4 miles east of Ashford, at Elham, and at Folkestone, but of these 

only the first two yielded complete information. Several borings entered the 

Corallian Beds but did not reach the base, while a number of others penetrated 

them in the district where they are incomplete, the upper portions 

having been removed by the Cretaceous denudations. 

The average width of the buried outcrop is 3 miles. It runs from the coast 

under Dover to Chatham and Rochester, maintaining for the greater part of 

the distance a nearly straight course. The easterly attenuation against the 

London landmass is not nearly so marked as in the other formations, the total 

thickness being over 300 ft. at Brabourne and still 270-80 ft. at Dover. 2 

These thicknesses are rivalled nowhere else in England outside the Yorkshire 

Basin. 

The most conspicuous and constant feature of the Kentish Corallian Beds 

is a 125-35 ft. mass of white coralline limestones. In general it doubtless 

corresponds with the great central block of white coralline or oolitic limestones 

elsewhere, the Osmington Oolite Series; but it is twice as thick as the 

Osmington Oolite Series at its thickest in Dorset or in Yorkshire, excepting 

only at North Grimston. Other features suggestive of North Grimston are 

remarkably thick masses of coral rag—one as much as 33 ft. thick at Dover— 

and the rag facies recurs at all levels throughout. 

It is interesting that this exceptional development of coralline limestones 

should be found close to the margin of the London landmass, against which 

all the other formations of the Jurassic thin out, while in Dorset, far from any 

shore-line, the oolites are only half as thick and contain no coral rag. It will 

be remembered that the great development of rag at North Grimston occupies 

an analogous position, close to the Market Weighton Axis; and that it and the 

superjacent portions of the Corallian Series, alone of all the Jurassic rocks, 

thicken towards the axis before being finally overstepped. The circumstances 

1 Based on G. W. Lamplugh and F. L. Kitchin, 1911, loc. cit., and Lamplugh, Kitchin and 

Pringle, 1923, loc. cit. 

2 The figures do not include the ironshot marls of the prcecordatum zone, which the Survey 

classed as Lower Corallian.

CORALLIAN BEDS: KENT 437 

therefore suggest that at both places we are dealing with actual fringing reefs 

that grew close to the shore. 

It was remarked that the expansion of the coralline oolite and rag at North 

Grimston might be in part accounted for by the Berkshire and Hambleton 

Oolite Series taking on a coralline facies as they approach the land. The same 

explanation probably applies in Kent, where there is a poor show of rock that 

can be definitely assigned to those beds, and nothing at all comparable with 

the thick Nothe Clay and Bencliff Grit of Dorset. 

Another analogy with North Grimston is provided by the thickness of the 

strata above the main mass of limestones—amounting at North Grimston to 

80 ft. At Dover there were 96 ft. of such beds, while at Brabourne they 

reached the astonishing thickness of 162 ft. No such development of Upper 

Calcareous Grit and Glos Oolite Series is known elsewhere in the British 

Isles, but better parallels can be found on the Continent. All the principal 

types of rock in other parts of England are represented, however, the most 

characteristic being the ironshot oolite or Westbury Iron Ore, with its fauna 

of Ringsteadice. 

It will be seen that the detailed correlation of the Kentish Corallian Beds 

with those of other parts of England presents special difficulties. The difficulties 

might not be insuperable were the rocks exposed in continuous cliffsections 

like those in Dorset, but with no more information than could be 

obtained from bore-holes to work upon, no very detailed correlation is 

possible. 

SUMMARY OF THE CORALLIAN ROCKS IN KENT 

Upper Calcareous Grit and Glos Oolite Series, max. 162 ft. 

The top of the Corallian Beds at Brabourne was taken above a 4-6 ft. band 

of 'greenish-grey glauconitic sandy mudstone with black specks', below which 

were about 14 ft. of 'blue-grey marly clay 5 and then ironshot oolite like the 

Westbury Iron Ore. The ore at Brabourne was only 3 ft. thick, all the rest 

of the succession down to the top of the main coralline limestones consisting 

of marls and marlstone or smooth argillaceous limestone, like a vastly expanded 

Sandsfoot Clay. In this were presumably included not only argillaceous 

equivalents of the Sandsfoot Grits, but also, judging by the fossils, 

strata of the age of the Trigonia clavellata Beds; for although little is known 

of the fauna of the Sandsfoot Clay, it is certainly not as rich as this would 

appear from the lists to be. The only possible correlation of the lower part 

of these upper beds is with the T. clavellata Beds, or the slightly later fossiliferous 

beds of Glos, in Normandy. 

At Dover the succession was somewhat more varied and the lower portions 

were lithologically more suggestive of the Trigonia clavellata Beds. Here the 

Westbury Iron Ore—'millet-seed ore . . . small shining brown globules of 

iron carbonate crowded in a slightly clayey or loamy matrix 5—w Tas 16 ft. 

thick and yielded a specimen of Ringsteadia. Seven feet of clay above it also 

contained the ironshot grains, and above that were 26 ft. of alternating 'oolitic 

limestone, calcareous claystone, muddy grit, bands of marly clay and layers 

of pisolitic rubble 5. These highest beds seem to have no counterparts in 

other regions in England; but the equivalent of the Westbury Iron Ore in the 

Boulonnais, the Oolithe d 5Hesdin-l 5Abbe, is 33 ft. thick and is succeeded by


some 16 ft. of hard marly limestones called the Caillasses d'Hesdigneul, 

which in the valley of the Liane are replaced by calcareous sandstone (the 

Gres de Wirwignes). 1 

Trigonia clavellata Beds? (Pars.), Osmington Oolite Series, Berkshire 

Oolite Series (Pars.), 125-35 ft. 

The highest 20 ft. of the beds grouped together as 'Corallian Limestones' 

by the Survey were described at Dover as 'creamy or greyish, soft, sandy 

limestone, with occasional layers of flaggy calcareous sandstone and incoherent 

sandy shale; and with rubbly bands mainly composed of rolled bits of 

shell and ooliths and containing many gasteropods, and Pecten, Lima, Ostrea, 

&c.'. Below this came 33 ft. of coral rag in 'irregular tabular masses', then 

12 ft. of 'creamy-grey soft calcareous stone of sandy texture, containing few 

corals, but many shells and Cidaris spines', separating the upper coral rag from 

another 60 ft. of 'coral-limestone in hard tabular masses set in a softer 

calcareous matrix, with bluish-grey partings of calcareous silt': this last 

contained abundant Terebratulids. 

At Brabourne corals were more or less common through the whole thickness 

of the limestones—134 ft. As already remarked, no such extensive development 

of coral rag as this is known elsewhere in England, for it exceeds 

even that at North Grimston; nor is there anything at all comparable with 

it either in the Boulonnais or in Normandy. If there were cliff-sections in 

Kent we might be able to trace out the coral rags at various levels into their 

contemporaneous shell-beds, or normal, non-coralline deposits, and so date 

them. But since coral rag of whatever age within the Corallian Series carries 

with it the same facies-assemblage, it is, as we have seen in Wiltshire and in 

Yorkshire, impossible to assign a date to any particular coral rag from internal 

evidence alone. The most we can hope to do is to fix limits to the 

period during which locally the coral regime endured. 

Even if we are right in assigning some of the argillaceous shelly beds above 

the coral rag to the Trigonia clavellata Beds, there is still no reason why 

a considerable portion of the coral rag should not also be developed on the 

horizon of part of the T. clavellata Beds; for in Dorset they have every appearance 

of being condensed. It seems improbable that coral growth would have 

stopped short in Kent while the Steeple Ashton reef was growing in Wiltshire, 

and when, as we have shown reason to believe, rag was still being formed 

in the south of the Yorkshire Basin. The less coralliferous uppermost 20 ft. 

of the limestones at Dover, in fact, seems from the description more like 

T. clavellata Beds than like any part of the Osmington Oolite Series in other 

parts of England. 

Berkshire Oolite Series (Pars.), Lower Calcareous Grit. 

The lower limit of the Berkshire Oolite Series (the important plane of 

transgression at the base of the martelli zone) can be fixed with more confidence. 

This lower part of the succession seems to bear a strong resemblance 

to that on the coast of Normandy. There the Osmington Oolite Series 

(Oolithe de Trouville) rests directly on a thin representative of the Berkshire 

Oolite Series, in the form of 10 ft. of shelly Trigonia hudlestoni Beds (lime- 

1 P. Pruvost and J. Pringle, 1924, P.G.A., vol. xxxv, pp. 34-5.

CORALLIAN BEDS: KENT 439 

stones and marls) crowded with the usual lamellibranchs and Perisphinctids, 

and recalling very forcibly the T. hudlestoni Beds of England. In addition the 

shelly limestones are locally ironshot, thus resembling in appearance the 

Elsworth Rock, on approximately the same horizon. 1 

In Kent, the two most complete records (Dover and Brabourne) are rather 

obscure in this part of the section, but some of the more recently described 

borings are highly suggestive. At Dover the coralline oolite was immediately 

underlain by 11 ft. of 'dark blue clay with massive marly structure, in places 

indurated to marlstone, with bands of black rather sandy clay; and containing 

large crushed plicatiloid ammonites, casts of Trigonia and other lamellibranchs'. 

This is suggestive of the Nothe Clay; but 27 ft. of clay and claystone 

followed below before the ironshot oolite elsewhere at the top of the 

Oxford Clay was reached, and these beds did not yield sufficient fossils to 

enable their age to be settled. 

At Fredville the Wealden Beds rest directly on strata below the main 

coralline limestones: 8 ft. of 'irregularly indurated pisolitic marlstone, passing 

down into 6 ft. of dingy, grey, impure, oolitic limestone with soft rubbly 

bands'; and below that were 12 ft. of 'compact blue-grey limestone, 

sparsely oolitic, with marly bands, Gryphcea, &c.'. These beds are suggestive 

of the Urchin Marls and Trigonia hudlestoni Limestones of Highworth, 

which, where they are thickest, do not contain the characteristic Trigonice; 

in fact the description of the Fredville strata applies exactly to some of those 

passed through in depth in the Red Down Boring, Highworth. Unfortunately 

these beds (like the Nothe Clay) were poorly fossiliferous and they can 

only be correlated with the Berkshire Oolite Series on stratigraphical and 

lithological grounds. They rested upon a bed which, by reason of its peculiar 

appearance, was easily recognized in a number of borings and served as a very 

useful datum-line—it was encountered at Fredville, Snowdown Colliery, 

Bere Farm, Brabourne, Chilham, Chilton and probably also at Guildford. 

This has already been described, in the preceding chapter, as forming the 

top of the Oxford Clay. It consisted of hard grey marlstone, packed with 

conspicuous dark-coated fossils, and its rich Cardiocerate and Peltocerate 

fauna proclaimed it to belong to the prcecordatum zone. Above it no Cardiocerates 

of any kind were found, but in it and below it they were abundant. 

No trace of the cordatum fauna was detected, though the presence of C. cf. 

excavatum (Sow.) and Rhynchonelloidea thurmanni (Voltz) in the dark-coatedfossil 

bed, and of Perisphinctes cf. variocostatum (Buckland) with abundant 

Chlamys fibrosa immediately below it, suggests that it may have been accumulated 

during a long period of time, perhaps spanning the prcecordatum, 

cordatum and martelli hemerae. In the absence of ammonites of the cordatum 

zone we must suppose that there is a non-sequence comparable with that at 

Quainton, Bucks., but no pebble-bed or other signs of erosion were found at 

the base of the presumed equivalents of the martelli zone. 

1 W. J. Arkell, 1930, P.G.A., vol. xli, p. 401.

CHAPTER XIV 


Zones (Plates xxxix, XL). Dorset Strata. 1 South Midlands. 

(Zonally unclassified) 

Pavlovia pallasioides 1 

Pavlovia rotunda 2 

Pectinatites pectinatus 

Virgatosphinctoides nodiferus 400 ft. of clays with stone 

bands; Oil Shale 150 ft. 

from base 

3 400 ft. of clays with stone 


Virgatosphinctoides wheatleyensis from base 

4 

400 ft. of clays with stone 


from base 

Subplanites spp. 5 

Gravesia irius 6 

Gravesia gravesiana 7 

Aulacostephanus pseudomutabilis 

Aulacostephanus yo 8 

Pararasenia mutabilis 

Rasenia cymodoce 

Hounstout Marls 

Hounstout Clay 

J 

absent 

Rhynchonella Marls and 

Lingula Shales 

Rotunda Nodules 

Swindon and Hartwell 

Clays with Lower Lydite 

Crushed Amm. Shales Bed at base 

YELLOW LEDGE 

Lower clays of Hen Cliff 

60 ft. 

MAPLE LEDGE 

Clays above and below 

The Flats, 120 ft. 

Shotover Grit Sand 

Wheatley ensis Nodules 

absent 

Generally absent 

Clays with Exogyra virgula9 Clays with Exogyra virgula 

and vertebrates 

9 

and vertebrates 

Clays with layers of Ostrea ! Clays with layers of Ostrea Clays with layers of Ostrea 

delta towards base 

1 


! Clays with layers of Ostrea 


1 


Pictonia baylei Rh. inconstans Clay clay (absent from Oxford) 

*» 2 The pallasianus zone of Chatwin and Pringle (1922), divided by Kitchin and Pringle 

(1923) into the zones of Pallasiceras pallasianus above and P. lomonossovi below; revised by 

Neaverson in 1924 and 1925. Pavlovia Ilova'isky, 1917, includes Pallasiceras and Holcosphinctesy 

according to Ilova'isky (1923, Bull. Soc. Nat. Moscou, vol. ii, p. 342) and Spath 

(1931, Pal. Indica, N.S., vol. ix, pp. 470-1). 

3 - 4 The Virgatites zone of Salfeld (1913) and later writers until Neaverson showed (1924-5) 

that the true Russian Virgatitids are unrepresented at this level. According to Dr. Spath, 

the Virgatites zones are at a higher horizon than the Pavlovia zones; and, in fact, Provirgatites 

scythicus (Michalski, plate XL, fig. 3) occurs in the basal Portland Sand of Hounstout 

Cliff. Dr. Spath informs me that he considers Virgatosphinctoides synonymous with Subplanites, 

but until a further study of these extremely perplexing ammonites has been published, 

I retain the names current hitherto. 

5 Subplanites Spath, 1925, Mon. Hunt. Mus. Glasgow, No. I, p. 120; type 'Virgatosphinctes 

y reisi Schneid (see T. Schneid, 1915, Geol. u. Pal. Abhandl., vol. xvii, pp. 305-414). 

6 » 7 Introduced by Salfeld (1913). Involute Gravesice of thegravesiana and irius groups appear 

to be unrepresented in any collections from this country, but crushed forms more evolute than 

these occur in the lower part of Hen Cliff, Kimeridge (two specimens found, 1932, by Dr. 

Spath, one in the writer's company; Salfeld stated that he found 'numerous examples'). 

8 Apparently never yet found in this country, but retained in accordance with Salfeld's 

zonal scheme. 

9 Mr. L. R. Cox (1930, Ann. Mag. Nat. Hist. [10], vol. vi, p. 298) has pointed out that the 

name Exogyra virgula (Defrance, 1821-31) should lapse as a synonym of E. striata (William 

Smith, 1817); but as there is no other E. virgula having prior claim to the name, and as it has 

become so firmly established in the literature of more than a century, I propose to sacrifice 

precision for intelligibility and retain it here. The case for Ostrea delta Smith is different, 

because O. deltoidea Lamarck is a Cretaceous species.


L DORSET 

(a) The Isle of Purbeck: Chapman's Pool and Kimeridge 1 

HE structural backbone of both the Isle of Wight and the so-called Isle 

of Purbeck is the anticlinal flexure described in Chapter III, which strikes 

east and west and plunges gently to the east. In the Isle of Wight the lowest 

strata are the Wealden Beds of Brixton Bay on the west coast. From beneath 

these, somewhere under the intervening sea, rise the Purbeck and Portland 

Beds of Purbeck; and on the west coast of the peninsula is seen the lowest 

stratum brought to the surface by the anticline, the Kimeridge Clay (map, 

fig- 77. P- 44*) • 

The Kimeridge Clay of the classic area of Purbeck crops out along the 

south-west side of the promontory as a narrow strip, measuring about 6 miles 

in length and never much exceeding 1 mile in width. It gives rise to a small 

but characteristic oasis of green clay-land, encircled behind by the lofty, 

steep-fronted escarpment of the Portland Stone, which rises well above the 

500 ft. contour and effectively shuts off the coastal lowland from the rest of 

the 'island 5. 

The sea frontage from Chapman's Pool in the east to Kimeridge and 

Brandy Bays in the west consists of low cliffs of grey and black, shaly clay 

with thin mudstone bands. While in general the erosion of the sea is rapid, 

keeping the cliffs vertical and free from talus, the mudstone or cementstone 

bands offer a stubborn resistance, the harder ones, often repeated by small 

faults, running out to sea as treacherous ledges for more than a mile from the 

shore. Among mariners, the Kimeridge Ledges have justly deserved an evil 

reputation. 

More famous than the ledges, however, is the 'Kimeridge Coal', a bituminous 

oil-shale, which for centuries has been dug along the cliffs and put to 

diverse uses. 

In the south-east corner of the semicircular bay of Kimeridge the surface 

of the fields is scarred by a number of irregular mounds, overgrown with 

brambles. Near by a curious round building known as Clavell's Tower 

stands on the summit of Hen Cliff overlooking the eastern entrance to the 

bay, while on the beach beneath a pile of shaped stones is to be seen at the 

point marked 'pier' on the map (PI. XX). These are the last vestiges of the 

Kimeridge alum industry, started at the beginning of the eighteenth century 

by Sir William Clavell, who built the neighbouring Smedmore House. 

Coker records 2 that that gentleman 'being ingenious in diverse faculties, put 

in tryall the makeing of allom, which hee had noe sooner, by much cost and 

travell, brought to a reasonable perfection, but the farmers of the allom workes 

seized to the king's use; and, being not soe skillfull or fortunate as himselfe, 

were forced with losses to leave it offe, and soe nowe it rests allmost ruined'. 

But 'Sir William Clavile, who[m] one disaster dismayed not' instead set up 

1 The spelling KIMERIDGE was used by H. B. Woodward in The Jurassic Rocks of Britain, 

by Damon in The Geology of Weymouth and the Coast of Dorset, and by most earlier authorities. 

The new form KIMMERIDGE was not heard of before Webster and Buckland introduced it in 

the nineteenth century and seems to have no justification. According to Hutchins (who in his 

great work on Dorset never deviated from KIMERIDGE) the spelling was KYMERICH in 1293 

and CAMERIC in Domesday Book (Hutchins, History of Dorset, 2nd ed., 1774, p. 193). 

2 Rev. Coker, 1732, A Survey of Dorsetshire, p. 46, London. 

H54371 H H 

441

KIMERIDGE 

CLAY 

PORTLAND 

SAND 

PORTLAND 

STONE 

PURBECK 

BEDS 

WEALDEN 

BEDS 

GREENSAND 

AND GAULT 

CHALK EOCENE 

FIG. 77. Sketch map of the 'Isle' of Purbeck, to show the positions of the type-sections of the Kimeridge Clay, Portland Sand and Purbeck Beds.

KIMERIDGE CLAY: DORSET COAST 443 

works for making glass and for boiling the sea-water to extract salt, using the 

Kimeridge oil-shale as fuel. This earned for it the name 'coal', but Coker 

records that 'in burning it yields such an offensive savoure and extraordinarie 

blacknesse, that the people labouring about those fires are more like furies 

than men'. Notwithstanding, it is still used as a substitute for coal in the 

cottages round about, constant familiarity apparently enabling the local nose 

to accustom itself to the strong fumes of sulphuretted hydrogen given off 

during combustion. 

By the middle of the eighteenth century ruins of buildings and heaps of 

ashes were all that remained of Sir William Clavell's projects, but in the latter 

half of the nineteenth century the bituminous shale was again exploited for 

the extraction of oil. The residual matter left after distillation of the oil and 

gas was sold as a deodorizer, decolorizer, disinfectant and manure. A ton of 

the shale was supposed to produce 7J gallons of naphtha, 10 gallons of lubricating 

oil, 1 cwt. of pitch, and some fine white paraffin wax and gas. 1 

Owing to the high content of sulphur (6-7 per cent.) and to the thinness 

of the workable seam, however, the cost of extraction has always been too 

heavy to allow the projects to become an economic success, and no satisfactory 

method of extracting the sulphur having yet been found, the present 

century has seen the works totally abandoned. 

The coal was described by Sir A. Strahan as 'a highly bituminous layer of 

shaly stone, about 2 ft. 10 in. thick with its partings, and of a dark brown 

colour, whence its local name of "blackstone". It breaks with a conchoidal 

fracture and readily ignites, burning with a bright flame and an offensive 

smell, and leaving a copious grey ash.' In 1917-18 the Government sank a 

series of test holes around Kimeridge in order to estimate the total yield of the 

field should exploitation become necessary owing to the shortage of other oils. 

The thickness of Kimeridge Clay visible between Chapman's Pool and 

Brandy Bay west of Kimeridge is about 700 ft., 2 although the three lowest 

zones, those of Pictonia bay lei, Rasenia cymodoce and Pararasenia mutabilis, 

are not exposed. The total thickness of clay present, therefore, may amount 

to more than 800 ft. 

The upper zones rise from beneath the Portland Stone and Sand along 

the west side of St. Alban's Head, where they are, however, largely concealed 

by extensive landslips (fig. 80). After a temporary incursion inland, along 

two deep valleys at Chapman's Pool, they strike the coast once more in the 

magnificent Hounstout Cliff, which rises 501 ft. above the sea (PI. XIX). As 

the Portland Stone forms only a capping, 50 ft. thick, to this cliff, the lower 

slopes are relatively free from slipped masses, and provide the best section of 

the uppermost zones of the clay in Dorset. 

The level at which the top of the Kimeridge Clay should be drawn 

is debatable, and a question analogous with the upper boundary of the 

Oxford Clay. Just as by time-honoured usage the Lower Calcareous Grit is 

classed as a part of the Corallian, although palaeontologically it is no more 

than a sandy upper part of the Oxford Clay, and the arenaceous facies undoubtedly 

begins at different horizons in different places, so the Portland 

Sands grade down imperceptibly into the Kimeridge Clay, from which there 

1 A. Strahan, 1918, 'Spec. Repts. Min. Resources', vol. vii, p. 27, Mem. Geol. Surv. 

2 As much as 930 ft. has been estimated by some authors, but this is certainly excessive.

BROAD OLD LIFE- GAULTER KIMERIDGE CLAVELL HEN CUDDLE CLAVELL'S HARD 

BENCH BOATHOUSE GAP BAY TOWER CLIFF OLD LEVELS IN OIL-SHALE 

ROPE LAKE 

HEAD 

T o S P H I N c T o I D E S 

Sfpr. 

8ANO 

X O N E s 

SPUR BELOW 

SWYRE HEAD 

FRESHWATER EQMONT HOUNSTOUT 

5TEPS BAY 

LEDGES 

COVERED 

r H CRUSH t j 

FIG. 78. Section along the cliffs of Kimeridge Clay from Broad Bench Promontory, near Kimeridge, to Chapman's Pool. Total distance 4J miles. 

Horizontal scale 3-4 in. = 1 mile, vertical scale just under 1 inch = 500 ft. (Outline, stone bands and faults after Strahan, 1898, 'Geol. Isle of Purbeck and 

Weymouth', Mem. Geol. Surv., pi. x; faults with a throw of less than 5 ft. omitted. The two faults near the lifeboat house have a combined 

throw of 40 ft.).


is usually little or nothing to distinguish them palaeontologically. The only 

comparatively constant datum is the base of the Portland Stone. 

Fitton originally placed the top of the Kimeridge Clay 120 to 140 ft. below 

the Portland Stone, assigning the intervening beds to the Portland Sand, 1 

and this plan was adopted by Sir A. Strahan in his Memoir on the Geology 

of the Isle of Purbeck. 2 Blake chose a datum about 100 ft. lower, giving the 

Portland Sand 244 ft., 3 while H. B. Woodward preferred 179 ft., grouping 

the lowest 40-50 ft. as 'Passage Beds'. 4 Then when the deep borings in 

Kent proved Portland Stone resting directly on clay, it was believed that the 

Portland Sands of Dorset were there represented by clay. Although no direct 

palaeontological evidence of this was obtained, the idea gained credence to 

such an extent that in 1925 Dr. Neaverson wrote: 

'There seems to be no doubt that the use of the term "Portland Sands" must be 

discontinued so far as the sandy beds below the Portland Stone Series of Dorset 

are concerned, since their faunal affinities are Kimeridgian rather than Portlandian 

and the sandy facies of Dorset and Bucks is represented by clays in the Kent 

borings. The ammonites from this horizon are, however, practically unknown . . 5 

The following summer, three years before his death, S. S. Buckman visited 

Chapman's Pool and, with the help of Mr. C. H. Waddington, began a study 

of Hounstout Cliff. He published a description of the beds below the Portland 

Stone, recording the fossils obtained in situ, and the result was to restore the 

Portland Sands to their original status, given them by Fitton and the early 

surveyors. 6 

In aband of white argillaceous cementstone, about 60-65 ft. from the top 

of the Portland Sands, specimens of Leucopetrites were found, a genus characterizing 

the lower levels of the Portland Stone (Behemothan Age) at Long 

Crendon, Bucks. Thus at least the upper half of the Sand (the St. Alban's 

Head Marl) belongs properly with the Portland Beds. 

Below the level at which Leucopetrites was found are about 30-40 ft. of 

sandy marls (the Emmit Hill Marls, see below, p. 491), and below them again 

the most prominent band in Hounstout Cliff—a 5 ft. block of massive yellow 

and blue-grey sandstone, which Buckman named the Massive Bed. Fallen 

blocks can be easily recognized, and Buckman found in them ammonites with 

quadruplicate ribbing which he identified with the Russian Virgatites scythicus 

and V. pallasi (Michalski). 7 This was unexpected, since the Russian Virgatites 

zone was originally believed by Salfeld and others to be represented in 

England by what have been known since Neaverson's revision as the Virgatosphinctoides 

zones. Of the two specimens figured by Buckman, there seems no 

doubt of the identity of at least4 Vscythicus with the Russian form; but this 

group (as may be seen from Michalski's figures) has a different ontogeny 

from the true Virgatites, and it has for some years been separated under the 

generic name Provirgatites. True Virgatites still remains to be found. 

1 W. H. Fitton, 1836, Trans. Geol. Soc. [2], vol. iv, p. 212. 

2 A. Strahan, 1898, 'Geol. Isle of Purbeck', p. 60, Mem. Geol. Surv. 

3 J. F. Blake, 1880, Q.J.G.S., vol. xxxvi, p. 195. 

4 H. B. Woodward, 189s,J.R.B., p. 192. 

5 E. Neaverson, 1925, Ammonites of the Upper Kim. Clay, p. 43. 

6 S. S. Buckman, 1926, T.A., vol. vi, p. 30. 

7 T.A., pi. DCLXXV: and see Michalski, 1890-4, Mem. Comite geol. Russie, vol. viii, pi. v, 

figs. 6, 7.

446 UPPER OOLITES 

The Massive Bed was the datum selected by Sir A. Strahan in his Memoir 

on the Isle of Purbeck at which to draw the arbitrary line of separation between 

the Portland Sands and Kimeridge Clay, and since it corresponds best with 

the base of the vague division established by Fitton, the originator of the 

term Portland Sand, there seem good historical reasons for following suit. 

Although Buckman and H. B. Woodward preferred a still more arbitrary 

invisible line 40-50 ft. lower, the Massive Bed has been adopted as the basement 

bed both by Mr. L. R. Cox in his palaeontological studies 1 and by 

Mr. M. P. Latter in his petrological account 2 of the Portland Beds, and its 

claims are accepted here. 

SUMMARY OF THE SUCCESSION IN THE CLIFFS FROM 

CHAPMAN'S POOL TO KIMERIDGE 3 

Pavlovia Zones ( + ?). 

The highest 120-130 ft. of the Kimeridge Clay according to this definition 

have so far yielded only a few ill-preserved ammonites, badly crushed. Dr. 

Neaverson recorded 'ammonites similar to H. pallasioides (though in a poor 

state of preservation)', 4 and the lower portions of the beds contain a number 

of other fossils, especially brachiopods. Buckman recognized four subdivisions 

(of which he included the highest in the Portland Sand). For the 

purposes of recording fossils it is essential that these should have names. Since 

the beds are best exposed in the face of Hounstout Cliff, I name the upper two 

divisions the Hounstout Marl and Hounstout Clay (see PL XIX and fig. 78). 

The succession is as follows: 

[Massive Bed above] 

4. HOUNSTOUT MARL, 40-50 ft.: blue sandy marl with thin bands of 

'stinkstone' (sandy cementstone giving off a strong odour when struck 

with a hammer); it extends down to the old road round the face of 

Hounstout. 

3. HOUNSTOUT CLAY : about 30 ft. of dark clay, apparently devoid of fossils. 

2. RHYNCHONELLA MARLS, about 20 ft.: grey marls with numerous 

Rhynchonella cf. subvariabilis Dav., a small Oxytoma, numerous small 

belemnites, and Cidaris spines; well seen at Pier Bottom on the west 

side of St. Alban's Head, where they first rise from the sea. 

1. LINGULA SHALES, 35-40 ft.: dark shales with Lingula ovalis auct. non Sow. 

[Rotunda Nodules below.] 

The highest beds yielding well-preserved ammonites belong to the rotunda 

zone. Where they are first seen, at the east end of Chapman's Pool, near the 

boat-house, they occupy the lowest 10-15 ft. of the vertical cliffs of black 

shale. The strongly-ribbed ammonites of the type that were long styled 

i biplex > can be seen from a distance, standing out in hundreds as hard claystone 

casts covered with a white chalky coating. Near the top they can be 

obtained more or less whole, often embedded in small nodules, and this bed 

is therefore known as the ROTUNDA NODULES. They have recently been 

collected carefully by Dr. Pringle and studied by Dr. Neaverson and Buckman, 

and were referred to the genera Pallasiceras and Lydistratites, which 

1 L. R. Cox, 1925-30, loc. infra cit. 

2 M. P. Latter, 1926, loc. infra cit. 

3 The ledges after A. Strahan, 1898, 'Geol. Isle of Purbeck', Mem. Geol. Surv., pp. 51-6. 

4 E. Neaverson, 1924, Geol. Mag., vol. lxi, p. 149.

Photo. 

Hounstout Cliff, Dorset. 

The finest section of the Upper Kimeridge Clay and Portland Sand in Europe. The capping is of Portland Stone. 

The arrow on the right denotes the position of the Massive Bed, here chosen as the base of the Portland Sand. 

RN = Rotunda Nodules, which dip steadily towards sea-level at the right-hand end of the picture. 

w.j. A. 

r 

> 

H 

M 

x 

HH


Dr. Spath regards as synonymous with Pavlovia. 1 P. rotunda is abundant, and 

Sowerby's holotype almost certainty came from here. Beneath the Nodules, 

at the foot of the cliff, the ammonites, though still white, are crushed flat. 

Most of them belong to the same species, but some are much larger, and 

Buckman thought that they might belong to Paravirgatites. 2 Other abundant 

fossils flattened in the bedding planes are Lucina minuscula and Orbiculoidea 

latissima. From the boat-house to the stream at the head of Chapman's Pool 

these beds form a hard slippery platform, on which the waves break. Westward 

they rise gently, providing a conspicuous datum easily followed below 

Hounstout until they rise to the top of the cliff some distance before reaching 

Freshwater Steps. 

Pectinatites, Virgatosphinctoides and Subplanites Zones. 

From the point where the conspicuous, hard, Crushed Ammonoid Shale 

rises to the top of the cliff in Egmont Bay, east of Freshwater Steps (Plate XIX), 

the next convenient datum is a thin stone band (1 ft.), which forms the base 

of the little cascade at Freshwater Steps, at a level estimated at no ft. below 

the top of the Crushed Ammonoid Shale. 

In 1931, after heavy gales, I had the good fortune to see a large part of the 

lowest 40 ft. of these clays exposed as smooth ledges, swept clear of shingle, 

in Egmont Bay. They were covered with flattened white ammonites, mainly 

of fine-ribbed forms resembling Pectinatites, and some identical with 4Keratinites' 

naso S. Buck, and nasutus S. Buck., 3 which seem to be, and have 

been stated by Dr. Spath to be, generically identical with Pectinatites. During 

the winter 1931-2 the shingle returned and completely covered these 

exposures; but the crumbling cliffs yield numerous fragments of crushed, 

small, fine-ribbed, involute ammonites, which can only be identified as 

Pectinatites. Specimens may also be seen upon the shale ledges about 100 yds. 

west of Freshwater Steps, at a level about 6-10 ft. above the Steps stone band. 4 

West of Freshwater Steps a continuous exposure of Kimeridge Clay 

extends for miles to Clavell's Hard, where the Blackstone or 'coal' was 

quarried, and this stretch of cliffs has remained until almost the time of going 

to press virtually a terra incognita. It is inaccessible from either end except at 

low tide, and the cliffs are unscalable from above. 

It was known that immediately above the Blackstone numerous small, 

crushed, fine-ribbed ammonites, very similar to those in Egmont Bay and at 

Freshwater Steps, abound on the ledges, and they have been generally 

identified as Pectinatitespectinatus and allied species. 5 The identification was 

first made by W. H. Hudleston as long ago as 1896, when reporting on an 

excursion of the Geologists' Association which he directed in that year: 

'Pyritized specimens of Ammonites pectinatus Phil, are abundant in the Kimeridge 

Coal—a fact not hitherto noticed, though very important by way of correlation. It 

serves to show that the Kimeridge Coal is on the horizon of the well-known and 

richly fossiliferous "Lower Portland Sands" of Swindon. Consequently we have 

1 See figures by Neaverson, 1925, loc. cit., pi. 1, figs. 6-10, and Buckman, T.A., 1926, 

pis. DXC (A-C), CCCLIII (C, D), DCXXXIX. 

2 S. S. Buckman, 1926, T.A., vol vi, p. 33. 3 T.A., pis. DCLII, DCLXIV. 

4 These I have recently photographed in situ. 

5 Two have been so figured by Neaverson, 1925, loc. cit., pi. I, figs, 4, 5.


no difficulty in believing that the Kimeridge Clay of Chapman's Pool is on the 

horizon of the Hartwell and Swindon clays, at least, approximately.' 1 

For the time at which it was written, this was a remarkable observation, and 

after having been overlooked for a quarter of a century it seemed to have 

been vindicated by the independent work of the Survey and Dr. Neaverson. 

The bed which yields these (pyritized) specimens identified as P. pectinatus 

and allied species most abundantly is the roof of the 4coal' seam. With them 

are found little radial plates, also pyritized, of the pelagic crinoid Saccocoma, 2 

which have such a restricted vertical and such a widespread lateral range 

(having been encountered on the same horizon in the Kent and Norfolk 

borings) that Messrs. Kitchin and Pringle have suggested making of them 

a separate subzone; at Kimeridge they have a total vertical range of 13 ft., 3 

and are most abundant just below the Blackstone. 

The ammonites, however, range up very much higher; in fact they may be 

found at intervals, with little apparent change, almost up to the stone band that 

sinks to the beach at Freshwater Steps, a measured distance of 155 ft. above 

the Blackstone. 4 Numbers are well shown upon the ledges on the east side of 

Rope Lake Head, where I have recently photographed them as they lie, since 

they invariably break if extraction is attempted. This level, where they seem 

to attain their acme, is between 20 ft. and 30 ft. above the Blackstone. 

To those who have not made a very detailed and comprehensive study of 

these 'pectiniform' ammonites, the conclusion seems unavoidable that between 

the Blackstone and the Crushed Ammonoid Shales {rotunda zone) all the 

clays, shales and thin stone bands must be assigned to an extended Pectinatites 

zone, 250 ft. thick. Ammonites which seem indistinguishable in the field 

from Pectinatites abound throughout this great thickness; and I had therefore 

determined on this course. Dr. L. F. Spath assures me, however, that the 

only true Pectinatites occur above the stone band at Freshwater Steps— 

namely in the highest 100 ft.—and that all the rest, although they are barely 

(if at all) distinguishable from Pectinatites in the young stages which are by 

far the most commonly represented, develop later along different lines. These 

abundant earlier forms he assigns to the genus Subplanites, and he considers 

that the small ammonites found at and about the level of the Blackstone, and 

identified by Hudleston and by Neaverson as Pectinatites, belong to the 

homceomorphous genus Lithacoceras (Hyatt, 1920). It is therefore interesting 

to note that Buckman also gave them a separate name (Pectinijormites, 1925, 

T.A.y pi. DLXVII) and placed pectinatus considerably higher. 

The 150 ft. of clays below and including the coal seam constitute the 

Virgatosphinctoides zones of Neaverson. 

The ammonites of these zones have given rise to much controversy, owing 

to their general similarity to Russian forms, which Dr. Neaverson showed, 

however, to be unrelated. Salfeld in 1913 stated that the beds were equivalent 

to the Russian Virgatites zone, although he admitted that he had never found 

in them a true specimen of Virgatites. s The Geological Survey at first 

accepted Salfeld's statement and believed that they had detected the Russian 

1 W. H. Hudleston, 1896, P.G.A., vol. xiv, p. 322. 

2 F. A. Bather, 1911, Sum. Prog. Geol. Surv. for 1910, pp. 78-9. 

3 Tested in 6 borings (J. Pringle, in lit.). 

4 Field-notes and measurements, 1932. 5 H. Salfeld, 1913, Q.J.G.S., vol. lxix, p. 425.


genus in a number of specimens recovered from the horizon of the oil-shale 

in borings at Corton, near Abbotsbury. With them were some large ammonites 

which were identified with another foreign genus, Pseudovirgatites, 

and this they made the index of a new zone to include the oil-shale. 1 

In 1925 Dr. Neaverson published his monograph upon these and other 

Upper Kimeridge Clay ammonites, showing that the similarity which the 

English forms bore to the foreign was due to homceomorphy, and the Corton 

and Kimeridge species previously regarded as Pseudovirgatites he named 

Virgatosphinctoides grandis, V. cf. nodiferus and V. delicatulus. 2 The stratigraphical 

position of the species was first determined inland, at Shotover and 

Wheatley, where they immediately underlie the xhm pectinatus zone, but their 

position in the type-section in Dorset is by no means so certainly fixed. They 

have been recorded at and below the level of the oil-shale; but if Dr. Spath 

is right they should be sought at a considerably higher horizon. (For further 

notes on the ammonites see footnotes on p. 440.) 

SUMMARY OF THE SUCCESSION FROM FRESHWATER STEPS TO CLAVELL's HARD 

Ft. 

Clays with crushed Pectinatites; some nodules about 25-30 ft. from base 100 

THE THREE STONE BANDS, drawn in Strahan's section (loc. cit.) . . 35 

The highest is the Freshwater Steps Stone Band. 

The lowest is the ill-named White Septarian Band, so called by Strahan in 

Brandy Bay. It is not septarian, but consists of hard white limestone 

with numerous paper-thin interlaminated clay-seams, giving it locally the 

appearance of tourmalinized slate. It forms the conspicuous white 

rocks east of Rope Lake Head, known by the fishermen as the Lias 

Rocks. Saurian vertebrae occur. 3 

Clays and shales with crushed Subplanites, &c., more or less hardened . . 35 

THE BASALT STONE BAND: hard black stone with conchoidal fracture; 

looks like a basalt sill; forms ledge bounding east side of Rope Lake Hole, 

and reaches beach level in W. corner of Brandy Bay . . . . 3 

Soft shaly clay, many crushed Subplanites . . . . . . 70 

ROPE LAKE HEAD STONE BAND: forms prominent ledge on W. side of 

extremity of Rope Lake Head . . . . . . . ij 

Clays and shales with crushed Subplanites, about . . . . . 1 0 

THE BLACKSTONE . . . . . . . . . . . I 

Clays and shales with crushed Subplanites, &c., and two conspicuous bands 

of cementstone, formerly worked for cement . . . . 140 to 150 

THE YELLOW LEDGE STONE BAND . . . . . . . . 2 

About 140-150 ft. below the 'coal' seam is a prominent band of hard mudstone 

known as the Yellow Ledge Stone Band. It rises at the ledge from which 

it takes its name (fig. 78) and, after running along the middle of Hen Cliff, 

reaches the top a hundred yards west of the Clavell Tower. This marks the 

line of division between Upper and Lower Kimeridge Clays, and it is the 

highest level at which Exogyra virgula has been found. 

1 Lamplugh, Kitchin and Pringle, 1923, "Concealed Mesozoic Rocks in Kent*, pp. 222-5 and 

pi. 11, Mem. Geol. Surv. 

2 E. Neaverson, 1925, Ammonites from the Upper Kim. Clay, Liverpool. 

3 No ammonites or traces of ammonites have been found for certain in this band, and it 

could not possibly have been the source of the Pavlovia figured by Damon as 'Am. biplex* and 

renamed A.Kimmeridiensi shy vonSeebach,as supposed by Buckman.—T.A. 1926, vol. vi, p. 38, 

and pi. DCLXXIII. From its state of preservation that specimen can only have come from the 

Rotunda Nodules.


Gravesia Zones. 

In the clays below the Yellow Ledge Stone Band, to the foot of Hen Cliff, 

the presence of flattened ammonites of the genus Gravesia was announced by 

Salfeld in 1913. He recorded the group of G. irius (d'Orb.) in the higher 

parts and the group of G. gravesiana (d'Orb.) below, thus (assuming his 

identification to be correct) providing an important link with the French and 

German succession. 1 Repeated search in more recent years, however, has only 

resulted in the discovery of two badly crushed specimens resembling the 

more evolute group of G.gigas. 2 

The downward limit of the Gravesia zones was defined by Salfeld as the 

Maple Ledge Stone Band, 3 which rises on the north side of the old pier, 

about 60 ft. below the Yellow Ledge Stone Band. 

One hundred yards east of Gaulter Gap the Maple Ledge Stone Band 

is faulted up above the top of the cliff, and there is no other datum by which 

to determine the displacement of the fault. Sir A. Strahan wrote: 4 'There is 

no reason, however, to suspect a large throw, and we may assume that the 

strata on the west side of the fault, while certainly below, are not far underneath 

the lowest seen on its east side. 5 

Aulacostephanus Zones. 

On the other side of the fault, and below the Maple Ledge Stone Band, the 

ammonite fauna again changes; and, as Salfeld found, down to the lowest 

levels exposed the clays yield abundant Aulacostephanus eudoxus, A. pseudomutabilisy 

and other species of the same genus, with Aptychi and small 

Aspidoceras. The total thickness of the Aulacostephanus zones exposed is 

about 120 ft. 

The axis of the Purbeck Anticline passes out to sea close to the Broad 

Bench Promontory, which forms the western horn of Kimeridge Bay. At the 

point, lying mainly between tide-marks, is a large flat shelf known as the 

Broad Bench, up which the muddy waves rush with spectacular fury in rough 

weather. It is formed by the lowest of the stone bands, which on account of 

repetition by small faults, gives rise to two similar benches nearer Kimeridge 

called The Flats, and so bears the name of The Flats Stone Band (PI. XX). 

On the west side of Broad Bench Promontory, in Hobarrow and Brandy 

Bays, the strata dip rather steeply below sea-level once more in the northern 

limb of the anticline, and all the zones are repeated in the space of less than 

a mile to the commencement of Gad Cliff. Farther west, beneath the precipitous 

walls of Portland Stone the highest zones are largely obscured by 

talus and wild undercliff like that beneath St. Alban's Head. 

The lowest beds exposed in the Isle of Purbeck, still belonging to the zone 

of Aulacostephanus yoy are seen for a short distance in Hobarrow Bay, northwest 

of the axis. Here The Flats Stone Band is thrown about 50 ft. up in the 

cliff by a fault, so that below it are seen lower beds than are visible in the crest 

of the anticline on the other side of Broad Bench Promontory. 

1 H. Salfeld, 1913, loc. cit., p. 425. 

2 Found by Dr. Spath in 1932. 

3 Inquiries among the fishermen at Kimeridge in 1931 showed that the ledges called Maple 

and Washing Ledges in Sir A. Strahan's time are no longer known by name. 

4 1898, loc. cit., p. 55.

PLATE XX 


Hen Cliff, Kimeridge. 

From the site of the old 'coal' pier. The Yellow Ledge Stone Band can be seen 

rather above the middle of the cliff, which is here formed mainly of the 

Gravesia zones. Note the muddy sea, and talus slopes continually being 

removed by the waves. 


Kimeridge Bay from The Flats. 

Hen Cliff and ClaveH's Tower on right of centre. Smedmore House among 

the trees in the distance on left, with Swyre Head behind. In the distance on 

right, waves are breaking on the mudstone ledges.

PLATE XXI 

Photo. W. J. A. 

Ringstead Bay and White Nothe Head. 

The headland is of Chalk, resting on thin Upper Greensand and Gault, which 

cut unconformably across the Kimeridge Clay. Holworth House near top of 

cliff on left, with two masses of Portland Beds and Purbeck Beds below (showing 

white) brought down by pre-Albian faults. 


Junction of Kimeridge Clay and Corallian Beds, Ringstead Bay. 

For explanation see pp. 379 and 451.


It was probably from the Aulacostephanus zones that the type specimens of 

Steneosaurus manselii Hulke and Ichthyosaurus enthekiodon Hulke were obtained 

; they were embedded in reefs exposed at low water in Kimeridge Bay. 

A jaw of a Teleosaurus was found by Mansel-Pleydell and figured by Hulke, 

which had fallen from the cliff during the winter, probably from the same 

zones. 1 

(b) Northern Limb of the Weymouth Anticline: Ringstead 

to Abbotsbury 

After a gap of 7 miles the Kimeridge Clay again appears in the cliffs of 

Ringstead Bay, where it is overlain by a small patch of faulted Portland and 

Purbeck Beds, and all are transgressed unconformably by the Gault (PI. XXI). 

The exposures have deteriorated considerably in recent years and fossils are 

now somewhat scarce. Sir A. Strahan considered it probable that the middle 

zones are cut out by the faults, but both the highest and the lowest zones are 

visible. A detailed lithological description was made by Waagen in 1865, 2 and 

Salfeld in his paper of 1914 identified some of the ammonites collected by 

Waagen and endeavoured to assign them to their proper beds, 3 but no 

modern palaeontological work has been published. 

The clays at the east end of the bay, which are partly succeeded by the 

Portland Sand and partly by the Gault, are poorly fossiliferous and all seem 

to lie above the rotunda zone. In the centre of the bay Waagen obtained 

abundant ammonites of the Aulacostephanus zones, below which, and passing 

westward into the lowest 100-140 ft. of the clay, Salfeld recognized evidences 

of both the Rasenia zones. From the presence of numerous flattened specimens 

of the typical Pararasenia mutabilis (Sow.) he assigned the higher parts of 

the lowest 140 ft. to the mutabilis zone; the cymodoce zone he recognized about 

10 to 13 ft. from the base. From the Aulacostephanus zones of this place came 

the type-material of Cardioceras anglicum Salf. and C. krausei Salf. 4 

The cymodoce and Pictonia zones can be conveniently studied in the low 

cliffs for about a mile along the west side of the bay (PI. XXI, lower figure). 

They contain many layers of large and well-preserved specimens of Ostrea 

delta, which weather out in hundreds on the beach. About 3J ft. above the 

base of the Kimeridge Clay is a 6-in. band of marl, partly indurated to form 

a hard limestone, almost entirely composed of Exogyra nana (Sow.), with 

occasionally E. prcevirgula Jourdy. The band of pale clay beneath contains 

abundant Rhactorhynchia inconstans and imperfect casts of Pictonice. s Waagen 

and subsequent writers have taken this by common consent as the basal bed 

of the Kimeridge Clay, and it is the lowest level at which Pictonice seem to 

occur (if not the only level). Immediately below is the Ringstead Coral Bed, 

the topmost member of the Corallian, in the equivalent of which Ringsteadice 

are found farther west. 

1 J. W. Hulke, 1869-80; see bibliography. 

2 W. Waagen, 1865, Versuch einer allgemeinen Classifikation, p. 4. 

3 H. Salfeld, 1914, loc. cit., pp. 204-6. 

4 H. Salfeld, 1915, 'Monographic der Gattung Cardioceras Neum. u. Uhlig, I\ Zeitschr. 

Deutsch. geol. Gesellsch.y vol. lxvii, pi. xx, figs 1-9. 

5 Proved by personal observation, which is not in accord with Salfeld's record of Ringsteadia 

from the Rh. inconstans Bed. Waagen's specimens of Ringsteadia probably came from the 

clays with ironstone nodules immediately below the Ringstead Coral Bed, where they may still 

be found in situ.


The high cliff west of Holworth House, at the east end of the bay, is still 

known as Burning Cliff from a spontaneous ignition of the bituminous shale 

which took place in 1826 and continued for four years. The heat that 

caused the shale to ignite was supposed to have been produced by the decomposition 

of iron pyrites. The fire was in progress when Buckland and De la 

Beche visited the district for the preparation of their paper 'On the Geology 

of the Neighbourhood of Weymouth 5, read in 1830. They state that it 

originally gave off flames for many months, but by the time of their visit it 

had considerably abated, there being no flame, only 'small fumaroles that 

exhale bituminous and sulphureous vapours, and some of which are lined with 

a thin sublimation of sulphur'. 'Much of the shale near the central parts', 

they wrote, 'has undergone a perfect fusion and is converted to a cellular slag. 

. . . Where the effect of the fire has been less intense, the shale is simply baked 

and reduced to the condition of red tiles.' 1 

If the oil-shale is on the same horizon as that at Kimeridge, several other 

zones must be present that have not been proved palaeontologically. 

At Black Head, west of Osmington, faults again bring down the base of the 

formation nearly to sea-level, and the Pictonia zone, with Rhactorhynchia inconstans 

and Ostrea delta, and the Ringstead Coral Bed at the bottom, can be 

traced close above the beach. Most of the Upper Kimeridge Clay is here cut 

out by the Cretaceous unconformity. Close to Osmington Mills, the Upper 

Greensand rests directly on the Rasenia zones, but higher zones succeed 

farther west, up to and above the oil-shale. The strata dip into the cliff at 

40 to 6o°, and where springs are given off at the base of the Chalk the clays 

have foundered, letting down enormous blocks of chalk, clay and greensand, 

and forming remarkable mud rivers, which flow slowly from the top of the 

cliff into the sea, after the manner of lava streams. 

Beyond Black Head the Kimeridge Clay strikes inland, passing in a westnorth-westerly 

direction along the north side of the Weymouth Anticline, 

giving rise to a deep valley parallel to that of the Oxford Clay, but separated 

from it by the Corallian ridge. It is not cut by the coast at the west end, 

but terminates at Abbotsbury faulted against Forest Marble. 

Little was known of the major portion of the clay along this outcrop before 

1917, when the boring of a number of test-holes for oil was commenced 

simultaneously at Kimeridge and at Corton, between Abbotsbury and Upway. 

The investigation was undertaken by the Department for the Development 

of Mineral Resources, oil-shale having been discovered at Portisham in 

1856. The borings struck a moderately rich seam of oil-shale up to ft. 

thick, but it proved of no commercial value, for it shared the same disadvantage 

as the Kimeridge shale, namely the excessively high content of sulphur. 2 

Palaeontologically the borings were more profitable, the level of the oilshale 

yielding Saccocoma, as at Clavell's Hard, associated with crushed 

ammonites identified as Virgatosphinctoides {Subplanites}). 

The district is chiefly remarkable for another economic product, a thick 

deposit of iron ore which is locally developed in the Rasenia zones at Abbotsbury. 

The average thickness of the ore is about 20 ft., but in the best section, 

in the sides of the lane leading from Abbotsbury to Gorwell, the total develop- 

1 Buckland and De la Beche, 1835, Trans. Geol. Soc. [2], vol. iv, p. 23. 

2 A. Strahan, 1918, 'Spec. Repts. Min. Resources', vol. vii, pp. 24-40, Mem. Geol. Surv.


ment of ferruginous and sandy rock amounts to 45 ft. The main ore consists 

of 20 ft. of 'crumbling reddish-brown oolitic rock, full of shining pellets of 

ore in a matrix of fine quartz sand . .. traversed by numerous long thin seams 

of concretionary iron 5, with thick beds of sand, more or less ferruginous, 

above and below. Not much attempt has been made to work the ore, probably 

on account of its being too siliceous. 1 

A remarkable brachiopod assemblage occurs in the ore bed, the commonest 

being Rhynchonella corallina Leym. and Ornithella lampas (Sow.), with which 

is associated Rh. inconstans. From this association Blake and Hudleston 

inferred the stratigraphical position with tolerable accuracy, giving it as their 

opinion in 1877 that the beds were 'at least on the horizon of the passage-beds 

to the Kimmeridge Clay', and definitely above the Sandsfoot Grits. 2 Later 

Douville and then Salfeld showed that the ore contains such ammonites as 

Rasenia uralensis (d'Orb.) and R. thurmanni (Oppel), indicative of the Rasenia 

zones of the Kimeridge Clay. 

The small size of the area over which the ore and sand deposits are developed 

is remarkable. Nothing similar is known at this horizon in any other 

part of England. 

(c) Southern Limb of the Weymouth Anticline: Weymouth and 

Portland 

The small area of Kimeridge Clay preserved on the southern limb of the 

Weymouth Anticline could scarcely be better described than in the words of 

Buckland and De la Beche, written in 1830: 3 

'The southern belt of Kimeridge Clay near Weymouth occupies a very small 

portion of the surface, constituting a triangular area, the base of which extends 

about a mile from Sandsfoot Castle westward to the Chesil Bank, whilst its apex is 

at Portland Ferry: but although so small a portion of this belt of clay is here visible 

on the surface, we have evidence of its submarine continuation from hence to 

Portland Island, in the clay bottom of the excellent anchorage of Portland Road, 

beyond which also it appears above the level of the sea in the base of the escarpment 

at the north extremity of the Isle of Portland, and along its west shore almost 

immediately south of the village of Chesilton. Hence it is clear that the Kimeridge 

Clay forms the fundamental stratum of the whole island, separated, as we have 

shown, from the Portland Stone by the Portland Sand and Sandstone. The rapid 

dip of all these strata towards the south causes the Kimeridge formations to sink 

below the level of the sea in the southern portion of the island; whilst that part of 

its western coast, whose base is composed of these perishable sands and clays, is 

defended from the tremendous south-western waves by a natural breakwater of 

enormous masses of Portland Stone that have fallen from the summit, and form 

a barrier against any further encroachments.' 

In the top of the Portland Sands on the west side of the island Salfeld 

found a specimen of' Perisphinctes gorei\ showing that at least the upper part 

of the sands here, as at Hounstout, should be classed with the Portland Sand. 

The same author recorded ammonites of the 'pallasianus' group (i.e. pallasioides 

or rotunda zones) in septaria in the clays below, and in flattened 

1 J. Pringle, 1920,' Spec. Repts. Min. Resources vol. xii, p. 222, Mem. Geol. Surv. 

2 J. F. Blake and W. H. Hudleston, 1877, Q.J.G.S., vol. xxxiii, pp. 273-4. 

3 1836, loc. cit., p. 22. 

854371 I 1


condition in shaly clays in the railway-cutting. 1 The lowest horizon of the 

Kimeridge Clay outcropping at the surface on Portland Island is the oilshale 

with Saccocoma. Between the island and the mainland is a gap, the 

highest beds exposed in the cliffs south of Sandsfoot Castle belonging to the 

Pararasenia mutabilis zone. An indication of the nature of the intervening clays 

that occupy this gap is afforded by a number of septaria washed up on the 

shore of Portland Roads. These have yielded some seven species of Aulacostephanus, 

together with other ammonites, and they indicate a development 

similar to that at Ringstead Bay. 

The low cliffs extending to the north towards Sandsfoot Castle, at the 

southern extremity of the mainland, begin with the lowest beds of the 

mutabilis zone and show a good section of the cymodoce and baylei zones. The 

junction of the latter with the top of the Corallian is not so easy to find here 

as in Ringstead Bay, but the Ringstead Coral Bed is represented by a thin 

band of oolitic ironstone, reminiscent of the Westbury Iron Ore, and this 

should certainly be regarded as the highest bed of the Corallian. The Exogyra 

nana Bed 2 is also conspicuous. 

(d) North Dorset and the Vale of Wardour 

After reappearing from beneath the Chalk of the Dorset Downs the 

Kimeridge Clay outcrops for about 20 miles through North Dorset, until it 

is cut off abruptly by the E.-W. fault along the north side of the Vale of 

Wardour. On the downthrown (north) side of this fault the Cretaceous rocks 

still overstep the Kimeridge Clay and Corallian, the edge of the Chalk and 

Greensand scarp resting upon the Oxford Clay. On the upthrown (south) 

side of the fault they have been stripped off. 3 

Concerning the Kimeridge Clay of this tract very little is known. The 

highest zones reach the surface only in a narrow belt within the Vale of 

Wardour, south of which the Cretaceous scarp, running westward to Shaftesbury 

and then south-westward, oversteps on to progressively lower zones. 

Evidence was obtained by the Survey from a well-shaft between Okeford 

Fitzpaine and Shillingstone that in the south the Gault rests upon some part 

of the Virgatosphinctoides zones. They also proved the Aulacostephanus 

pseudomutabilis zone near Okeford Fitzpaine Church,in a brookside. The only 

clear section in the district is a large clay-pit south of the railway station at 

Gillingham, which exposes 25 ft. of clays falling entirely within the Rasenia 

zones. The clays are black and selenitic, and contain abundant Exogyra 

virgula, with Lingula ovalis, Ostrea delta and other shells, and bones of 

Ophthalmosaurus pleydelli Lyd. Dr. Pringle has recorded Rasenia cf. stephanoides 

(Oppel), R. cf. trimerus (Oppel) and numerous specimens of [Pararasenia] 

desmonota (Oppel). 4 


2 Salfeld's Bed 19, loc. cit., p. 202. Salfeld here places Pictonice below the Exogyra nana 

Bed, just as I have found them (in fragments) at Ringstead (see footnote on p. 451). 

3 Once the hard Chalk and Greensand had been removed, erosion of the Kimeridge Clay 

proceeded rapidly, so that now the Chalk on the downthrown side of the fault towers several 

hundred feet above the clay vale on the upthrown side. 

4 J. Pringle, 1923, 'Geol. Shaftesbury', Mem. Geol. Surv., pp. 40-1; and Sum. Prog, for 

1921,p. 112.

KIMERIDGE CLAY: SWINDON 455 

II. WILTSHIRE, BERKSHIRE, OXON. AND BUCKS 

(a) Wiltshire 

North of the Vale of Wardour the Kimeridge Clay is concealed for 11 miles 

beneath the extension of Salisbury Plain, formed by the overstepping of the 

Chalk westward to Mere, Warminster and Westbury. North of this the clay 

reappears for a few miles at the mouth of the Vale of Pewsey, where the 

Pavlovia zones have been worked in small brickyards, and where there are 

also (badly exposed) Portland rocks, as in the Vale of Wardour. 1 It is soon 

overstepped once more by Lower Greensand and Gault for 5 miles nearly to 

Calne. From Calne onwards the outcrop is uninterrupted until beyond the 

border of Berkshire; then at Faringdon a narrow tongue of Lower Greensand 

extends again on to the Corallian. 

Throughout most of this tract, excepting the short distance in the Vale of 

Pewsey, the Kimeridge Clay is incomplete, being unconformably overlain by 

the Lower Greensand. Swindon, however, lies on a synclinal trough in which 

are preserved not only the higher Kimeridge zones but also the Portland and 

Purbeck Beds. The limestones form the capping of the hill on which the Old 

Town is built, while in the steep slopes below numerous brick-pits, opened 

to provide building materials during the rapid growth of the new railway 

town in the plain to the north, have at one time exposed almost the whole 

succession of the Kimeridge Clay. These pits, some of them of great size, 

yielded a rich harvest of vertebrate skeletons, belonging to Ichthyosaurus, 

Ceteosaurusy Omosaurus and rare Chelonia, some of which were described by 

Owen in his monographs of the Mesozoic Reptilia. Most of the vertebrate 

remains came out of the lower beds, especially the Rasenia and Aulacostephanus 

zones, as at Kimeridge. 2 The pits from which they came have for 

many years been abandoned. 

Evidence has been obtained at Swindon for the presence of all the known 

zones of the Kimeridge Clay except that of Subplanites, up to and including 

that of Pavlovia rotunda, and less certainly that of P. pallasioides. Upon this 

the Portland Bedsôm zone) rest non-sequentially, with a phosphatic pebblebed 

at the base, containing derived fossils of rotunda and doubtfully pallasioides 

dates (the Upper Lydite Bed). Notwithstanding this apparently almost 

complete representation of its component parts, the formation reaches only 

some 300 ft. in thickness, or less than one-third of the total on the Dorset 

coast. This is in large measure due to the fact that the 400 ft. of the Dorset 

pectinatus and Subplanites zones are only represented by some 35-45 ft. of beds. 

The most remarkable feature of the Kimeridge Clay at Swindon, a feature 

common also to the district about Oxford, is the development of the pectinatus 

zone in an arenaceous facies. Although all the other zones are represented 

by normal clays, the pectinatus zone consists of thick beds of sand with 

large doggers of hard calcareous gritstone. These have been called the 

Shotover Grit Sands, on account of their good development, with abundant 

1 A. J. Jukes-Browne, 1905, 'Geol. Country S. and E. of Devizes*, Mem. Geol. Surv., p. 5 

(Ammonites pallasianus is said to have been 'one of the commonest fossils'). 

2 Tholemys passmorei Andrews, found by Mr. A. D. Passmore in a temporary excavation 

and presented to the British Museum, was described as the most perfectly-preserved turtle 

ever found in the English Kimeridge Clay: C. W. Andrews, 1921, Ann. Mag. Nat. Hist. [9], 

vol. vii, pp. 145-53.


fossils, on Shotover Hill, Oxford. Their equivalence to a part of the Kimeridge 

Clay as low down as the oil-shale of Kimeridge was suggested in 1896 

(see above, p. 447) by W. H. Hudleston, on the ground of the occurrence of 

P. pectinatus (Phil.), but the correlation was overlooked for twenty-five years. 

The true position was misunderstood by Salfeld, who correlated the Shotover 

Grit Sands at Swindon and Oxford with a part of the Portland Sands of Dorset 

above the pallasioides zone, and at the same time placed them above the 

Hartwell Clay (and the Atherfield Clay!). 1 Messrs. Chatwin and Pringle, of 

the Geological Survey, arrived independently, in 1921, at the same conclusion 

as Hudleston, and they, with the help of Hudleston's collection, gave 

the first accurate description of the sequence on Swindon hill. 

SUMMARY OF THE SEQUENCE AT SWINDON 2 

Pavlovia Zones (SWINDON CLAY AND LOWER LYDITE BED). 

On the floor of Okus Quarry, on the top of the west end of the hill, where 

the Portland Limestones are still actively quarried, a thin band crowded with 

dark phosphatic pellets and small lydite pebbles separates the glauconitic base 

of the Portland Stone (or strictly speaking the stony Portland Sand) from the 

clay below. Among the pebbles are commonly found rolled and phosphatized 

fragments of small ammonites belonging to the rotunda and possibly 

pallasioides zones, and it is concluded that these have been washed out of the 

SWINDON CLAY SHOTOVER CS.IT SANDS 

FIG. 79. Section in railway-cutting west of Swindon Town (Old Swindon) Railway Station. 

(After H. B.Woodward, 1 8 9 5 , v o l . v,p. 212, re-drawn.) This cutting, made in the early 

'nineties, established finally the inferred succession of the strata at Swindon. 

upper part of the Swindon Clay. This Upper Lydite Bed has a wide extent 

in Oxfordshire and Buckinghamshire, where it always marks the local base of 

the Portland Series, and was called by Hudleston the 'basal conglomerate of 

the Portlands 

5. 3 

The highest surviving Kimeridge stratum is the Swindon Clay, a blue clay, 

weathering brown, 15-20 ft. thick. The top forms the floor of Okus Quarry, 

but the lower parts, which are more sandy, are not now exposed, except 

occasionally in graves in the cemetery. The whole is very poorly fossiliferous, 

but Dr. Neaverson writes: 'The basal portion . . . consisting of a hard, 

greenish marl, contains fragments of ammonites which appear to be referable 

to Pallasiceras [= Pavlovia], and poorly preserved specimens are occasionally 

found in the blue clay which forms the mass of the Swindon Clay.' 4 Dr. 

1 Loc. cit., 1913, and 1914; see especially, 1914, p. 128, Table I. 

2 Based on C. P. Chatwin and J. Pringle, 1922, Sum. Prog. Geol. Surv. for 1921, pp. 162-8 

(with emendations). 

3 W. H. Hudleston, 1880, P.G.A., vol. vi, p. 345. 

4 E. Neaverson, 1924, Geol. Mag.t vol. lxi, p. 148.

KIMERIDGE CLAY: SWINDON 457 

Kitchin has more recently recorded that an excavation lately made in the top 

of the clay yielded ammonites indistinguishable from Pavlovia pallasioides. x 

At the base is another 8-in. pebble-bed, the Lower Lydite Bed, resting 

on the 

Pectinatus Zone (SHOTOVER GRIT SANDS). 

The Shotover Grit Sands, 35-45 ft. thick, consist for the most part of 

yellow calcareous sands with enormous spherical doggers of hard gritstone, 

their old name being 'Lower Portland Sands'. Fossils are uncommon in all 

but the highest 6-8 ft., which consist of green and red marly sandstones, sands 

and clays, with abundant Exogyra nana and a rich fauna of other mollusca, 

including Pectinatites pectinatus (Phil.) 2 and P. eastlecottensis (Salf.). 3 Hudleston 

collected a fine series of fossils from a cutting during the construction 

of the M.S.W.J.Railway (fig. 79), but little below the Portland Beds can now 

be seen there. According to Messrs. Chatwin and Pringle: 

'These upper beds were at one time (1887) well exposed in the road-cutting below 

Victoria Street, and the section was recorded by H. B. Woodward. A similar section 

was visible in May 1921 in a disused clay-pit south of Stafford Street; this pit has 

now been filled in, but from time to time the beds are exposed when graves are dug 

in the old cemetery, in the slope overlooking Clifton Street. Many fine uncrushed 

ammonites have been found in the material thrown out in grave-digging.' 4 

There is now a fine section showing sands with enormous doggers, overlain 

by the Exogyra Bed and Lower Lydite Bed, at the north-west end of the hill, 

above Hill's brickyard. 

Virgatosphinctoides Zones. 

The Grit Sands pass down gradually into clays, the junction having been 

exposed in Turner's upper brick-pit, west of Drove Road, on the north-east 

side of the hill, and a better section of the clays also in Hill's brickyard, below 

Okus Quarry. From these beds a number of ammonites with semi-virgatotome 

ribbing have been collected, which were formerly identified as Virgatitesy 

but would now be called Virgatosphinctoides. There appears to be no 

indication of a separate Subplanites zone either here or in Oxfordshire. More 

detailed study of the ammonites is needed, however. 


Messrs. Chatwin and Pringle record that a specimen of Gravesia exists in 

the Hudleston collection from Swindon, ^but the zone has never been identified 

in situ, and there is no longer any exposure likely to show it. 


In Turner's lower pit, known also as Bazzard's pit (now filled up with 

1 F. L. Kitchin, 1926, Ann. Mag. Nat. Hist. [9], vol. xviii, p. 452. 

2 A topotype of A. pectinatus Phil, (from Shotover Hill, Oxford) in the Oxford University 

Museum, has been figured by Buckman, T.A., pi. CCCLIV; and another is figured here 

(pi. xxxix). 

3 The type, figured Q.J.G.S1913, vol. lxix, p. 430, pis. XLI, XLII, was believed by Salfeld 

to have come from the Upper Lydite Bed, and he made it the index of a separate zone above 

the Swindon Clay. Chatwin and Pringle proved that it came out of the upper part of the 

Shotover Grit Sands (loc. cit., p. 166). Buckman assigned it to a new genus, Wheatleyites, 

which Dr. Spath considers synonymous with Pectinatites (1931, loc. cit., p. 468). 

4 C. P. Chatwin and J. Pringle, 1922, loc. cit*; p. 166.


rubbish and water, and having allotments over a large part of its floor), there 

were formerly exposed leathery bituminous shales, in which Salfeld recorded 

numerous crushed specimens of Aulacostephanus pseudomutabilis and A. 

eudoxus, together with Aptychi. 

Rasenia and Pictonia Zones. 

The presence of the Rasenia zones at Swindon is proved by some specimens 

collected by Hudleston from The Wharf, while Salfeld recorded that a fragment 

of Pictonia bay lei had been found in Turner's lower pit (Bazzard's). At 

the base of an old clay pit in Telford Road he collected abundant Prionodoceras 

serratum (Sow.), which may have come from the base of the bay lei zone 

or from the highest layers of the Corallian, though no Ringsteadia were found 

(see p. 395). 1 At the time work in Turner's lower pit was in active progress, 

a section was probably seen displaying clays of the Pictonia, Rasenia and 

Aulacostephanus zones, the two last yielding the vertebrate remains. The 

Rasenia and Pictonia zones are still visible in the brickyard at Stratton St. 

Margaret, north-west of the bridge where Ermine St. crosses the railway. 

They consist of brick-clays with Ostrea delta and some lines of septarian 

crackers containing the zonal ammonites well-preserved. The same zones, 

and the junction with the Upper Calcareous Grit, were formerly to be seen 

in an old brickyard at Wootton Bassett. 2 

During the construction of the Great Western Railway some of the longest 

and finest sections of the Kimeridge Clay in the country must have been seen 

in the vicinity of Swindon. Deep cuttings pass through the lower beds for 

several miles between Swindon and Wootton Bassett, and also near Stratton 

St. Margaret and South Marston; while near Bourton the upper beds were 

laid bare, and a small portion of them has recently been reopened in making 

a siding. Unfortunately no accounts of these cuttings were published. 

Beneath the small Portlandian outlier of Bourton, near Shrivenham, the 

Upper Kimeridgian Beds are essentially the same as at Swindon, except that 

the top part of the Swindon Clay is sandy (see p. 508). A temporary excavation 

made in 1931 near Bourton End showed 3 ft. of Swindon Clay, greenish and 

sandy, with the Lower Lydite Bed at the base, resting on blue sands with 

large doggers, pierced to a depth of 4 ft. The lydite pebbles were exceedingly 

abundant. 3 

(b) Berkshire Vale and Oxford 

Except for a momentary interruption near Faringdon, w T here a narrow strip 

of Lower Greensand, marked by high sandy ground, oversteps across the 

Kimeridge Clay on to the edge of the Corallian escarpment, the outcrop of 

the clay forms a continuous low-lying vale from Swindon to the Thames at 

Abingdon. This is the Vale of the White Horse in the narrower sense: the vale 

of the Gault and Kimeridge Clays, bounded on the north by the Corallian 

ridge, beyond which lies the wider but separate valley of the Thames. 

Along the greater part of the Vale of the White Horse, the Gault and 


2 The holotype of Pictonia costigera was collected here; see T.A., 1927, pi. DCCXVI. 

3 Record kindly forwarded by my brother, Mr. J. O. A. Arkell, of Bourton End. I inspected 

the tip-heap, but found no fossils, only abundant lydite pebbles.

KIMERIDGE CLAY: THAME AND AYLESBURY 459 

Kimeridge Clays are in contact, possibly because, as explained on p. 77, the 

outcrop obliquely crosses the continuation of the Birdlip Axis. The relations 

of the two are w r ell seen at Culham brickyard, near Abingdon, where the 

Douvilleiceras mammillatum zone of the Gault (Middle Albian), 1 with a basal 

sandy pebble-bed, rests on grey sandy Kimeridge Clay, possibly of pectinatus 

date, or rather earlier. There are now very few other sections, though in days 

gone by the base of the Kimeridge Clay was to be seen in a brick-pit at Stanford 

in the Vale and a small exposure of the upper portion is still provided by 

another brick-pit at Drayton, near Abingdon. 

On either side of the Thames south of Oxford, the outcrop extends northward 

for several miles up the dip-slope of the Corallian limestones, as long 

spurs with sides rising steeply from the plateau and capped by Lower Cretaceous 

sands. The western spur forms Boar's Hill and Cumnor Hurst; the 

eastern spur forms the lofty ridge that runs from Garsington to Shotover, 

and carries, in addition to the Cretaceous sands, a thick layer of Portland Beds 

with traces of Purbecks. At the end of each ridge there is a large brick-pit, 

the one at Shotover giving a nearly complete exposure of the Kimeridge Clay. 

Eastward, around the south of Otmoor, the boundaries are obscurely 

defined owing to the dwindling of the Corallian limestones, but beyond the 

valley of the River Thame a third spur reaches northward to Brill and Muswell 

Hills. Here there are again exposures. 

Still farther east the relics of a fourth spur, capped by outliers of Portland 

and Purbeck Beds and Cretaceous sands, survive as the hills at Quainton and 

Oving. The intervening country is dotted with a broken covering of Portland 

Beds, dissected by the Thame and its tributaries, and it presents in consequence 

an undulating scenery quite different from any to be found in other 

parts of the inland outcrop. 

Seven miles north-east of Aylesbury the Kimeridge Clay is completely 

overstepped by the Gault and Greensand, and disappears under the Dunstable 

Downs, not to reappear for 32 miles. 

Within this tract the best exposures are the brick-pits at the extremities of 

the two spurs on either side of Oxford, at Cumnor Hurst and Shotover, and 

a third brickyard on the eastern face of the Shotover ridge, at Littleworth, 

close to Wheatley. On the eastern side of Brill Hill, Prof. Morley Davies has 

described a valuable section of the lower beds at Rids Hill Brickyard, while 

the uppermost beds are or have been seen in other small brickfields at Long 

Crendon, Thame, Hartwell and Aylesbury. These exposures will be mentioned 

in connexion with the Hartwell Clay, a consideration of which is best 

left until the succession near Oxford has been described. 

In the vicinity of Oxford the total thickness of the Kimeridge Clay is about 

150 ft., although in places, as at Cumnor Hurst, it is still more reduced by 

pre-Cretaceous denudation. 2 This is only half the thickness at Swindon, but 

nevertheless the chief features of the Swindon succession, such as the Swindon 

Clay and the Shotover Grit Sands, are present, and the only zones which 

appear to be generally missing are those of Pictonia, Gravesice, and Sub- 

1 See Spath, 1923, 'Mon. Ammon. Gault', Pal. Soc., part i, p. 4. 

2 Such denudation probably accounts for the low records of 94 ft. obtained in borings at 

Wantage and Culham [see 'Water Supply of Berks.', p. 89, and 'Water Supply of Oxon.', p. 42, 

Mems. Geol. Surv.].


planites. A substantial proportion of the total gap is probably represented, as 

at Swindon, by the Lower Lydite Bed. 

At Chawley Brickworks, Cumnor Hurst, the Lower Greensand is seen 

resting on deeply channelled clays of the Virgatosphinctoides zone, about 

20 ft. thick. In the past some relic of the pectinatus zone must have been 

encountered, for specimens of the zonal index fossil from this locality are 

preserved in the Oxford University Museum. The rest of the pit shows the 

upper Aulacostephanus zone, with A. eudoxus, Exogyra virgula and Saurian 

bones. 1 

The sections at Shotover and Wheatley Brickyards are much more complete 

and either here or at Brill the whole of the Kimeridge Clay has at one 

time or another been described. 

SUMMARY OF THE SEQUENCE NEAR OXFORD, AT SHOTOVER, CUMNOR, 

WHEATLEY AND BRILL 2 

Pavlovia Zones (SWINDON CLAY AND LOWER LYDITE BED). 

During 1930 and 1931 a sand-pit above the Shotover Brickyard has been 

worked farther back into the hill so that it now exposes not only the Swindon 

Clay but also the Upper Lydite Bed and the basal portion of the green 

Glauconitic Beds of the Portland Stone Series. The Upper Lydite Bed is 

about a foot thick and very conspicuous. 

The SWINDON CLAY is a greenish-grey sandy clay and has at the base, as 

at Swindon and Bourton, the LOWER LYDITE BED. The full thickness of the 

clay is difficult to estimate, for it has acted as a slide-plane upon which the 

superincumbent Portland Stone has slipped down the hill-side, and it is in 

consequence much disturbed. The two lydite beds are only some 5 ft. apart, 

but an unknown thickness of the clay at the point where it is seen may have 

been squeezed out, since the beds are inclined at a high angle, in places 

approaching the vertical. 

At Wheatley 12 ft. of the Swindon Clay 3 are exposed, but the top is not 

seen. Here small brown nodules occur in the clay, not uncommonly yielding 

fragmentary ammonites of the type of Pavlovia rotunda (Sow.). Fossils seem 

to be no longer found at Shotover, but Dr. Douglas observed in 1910 that 'a 

number of Kimeridge fossils, including the species usually termed A. biplex, 

were obtained from this clay-band'. 4 The species usually termed A. biplex at 

that time comprised the 'genera' Pallasiceras, Lydistratites, Holcosphinctes and 

Aposphinctoceras, all of which Dr. Spath considers synonymous with Pavlovia 

Ilova'isky. 5 

Pectinatus Zone (SHOTOVER GRIT SANDS). 

At the type-locality, the sand-pit above the brickworks on Shotover Hill, 

these consist of 16 ft. of yellow and whitish coarse sand with large doggers, 


2 Based on J. Pringle, 1926, loc. cit., pp. 66-75. 

3 Buckman's name for the Swindon Clay here was Littleworth Lydite Clay. 

4 J. A. Douglas, 1910, Geol. in the Field, p. 206. 

5 The type of Aposphinctoceras decipiens Neaverson was figured by Miss M. Healey as 

*Olcostephanus pallasianus (d'Orb.)', Q.J.G.S., 1904, vol. lx, p. 60, pi. XII, figs. 1 and 2, and 

came from Chippinghurst, Oxon., apparently from the Swindon Clay. This was previously 

known as A. biplex.


some of them resembling enormous cannon-balls. The sands and doggers, 

especially towards the top, contain abundant small lydite pebbles. The 

doggers are crowded with shells, of which the commonest are large Pernas 

(Isognomon bouchardi and another species), Ostrea expansa Sow., Exogyra 

thurmanniy a Quenstedtia, and various other bivalves. Among ammonites it 

suffices to mention those species of which this is the type-locality: Pectinatites 

pectinatus (Phil.), 1 Paravirgatites pringlei Buck., 2 Paravirgatites paravirgatus 

Buck., 3 and the horned Pectinatites ('Keratinites') naso Buck. 4 The name 

Shotover Grit Sands serves to distinguish them from the prior-named Shotover 

Sands of Lower Cretaceous (Wealden) age, which cap the hill. 5 Buckman 

also distinguished a Shotover Fine Sand, but this is probably no more 

than a local variant of the Shotover Grit Sands, which are here understood as 

including all the sands between the Swindon Clay and the Virgatosphinctoides 

zones. 

At Wheatley brick-pit the Shotover Grit Sands are only 9^ ft. thick, consisting 

of 4 ft. of friable brown sandstone, crowded with shells, overlying 

5\ ft. of lilac sandy clay. From the soft sandstone the fossils fall out in perfect 

condition, making the collection of specimens a much easier task than from 

the iron-hard doggers at Shotover. Very perfect Trigonice and other fossils 

may be obtained, forming a noticeably different assemblage from that at 

Shotover, but containing the same ammonites with numerous additions. 

From this bed were obtained the type specimens of seven species of Pectinatites 

(figured by Buckman as ' Wheatleyites' and *Keratinites'). 

Virgatosphinctoides Zones. 

Beneath the sands at Shotover about 10 ft. of blue-black clay is dug for 

bricks, and out of this come large irregular nodules or crackers, containing 

white-coated fossils of the Virgatosphinctoides wheatleyensis zone. 

At Wheatley, the two Virgatosphinctoides zones together consist of some 

18 ft. of dark clays, with layers of septarian nodules or cementstone crackers, 

from which Dr. Neaverson has obtained numerous ammonites. These 

nodules at Wheatley are the source of the types of the following: 

Virgatosphinctoides wheatley ensis Neav., AUovirgatites tutcheri Neav., pi. 111, 

1925, pi. I, fig. 1. 

fig. 2. 

V. delicatulus Neav., pi. 1, fig. 2. 

A. robustus Neav., pi. HI, fig. 3. 

Sphinctoceras crassum Neav., pi. 11, fig. 1. A. versicostatus Neav., pi. 111, fig. 4. 

while at Shotover were obtained the types of Virgatosphinctoides nodiferus 

Neav. (pi. iv, fig. 1), Sphinctoceras distans Neav. (pi. iv, fig. 3), AUovirgatites 

woodwardi Neav. (pi. in, fig. 1). The V. nodiferus came from the 

clay above the nodule band, immediately below the Shotover Grit Sands, 

and on the strength of this Dr. Neaverson recognizes a separate zone of V. 

nodiferus; but it remains to be shown whether it can be recognized elsewhere. 

At Chawley Brickworks, Cumnor Hurst, the clays on which the Lower 

Greensand is now seen to rest belong to the Virgatosphinctoides zones, which 

may be about 22 ft. thick. They contain the same cementstone crackers, 

1-4 See T.A., pis. CCCLIV, DLXII, CCCVIII, DCLII. Dr. Spath considers Buckman's genus 

Shotoverites (type S. pringlei) identical with Paravirgatites (loc. cit., 1931, p. 472). 

5 The freshwater Wealden sands were so named by Prestwich and other early writers; the 

alienation of the name for the Kimeridgian dates from Blake (1880, pi. VIII). (See G. W. 

Lamplugh, 1908, c Geol. Oxford', Mem. Geol. Surv, p. 68; and 2nd ed., p. 87.)


with V. wheatley ensis, Allovirgatites tutcheri, Modiola (Musculus) autissiodor 

ensis, &c. The zones are also exposed at Rids Hill, Brill, where they are the 

highest seen in the old brick-pit. 


No evidence for the presence of either fauna or strata of Gravesice date has 

been found in the Oxford district, and there seems no doubt that the zones 

are wanting. 


At Wheatley, Cumnor and Rids Hill Brickyards the Virgatosphinctoides 

clays rest directly upon dark shaly clays of the Aulacostephanus zones, with 

Exogyra virgula and Aptychus latus. To the base of the pit at Wheatley 8 ft. 

are seen, most of which belongs to the pseudomutabilis subzone, since A. 

eudoxus abounds; but Dr. Pringle has recorded Physodoceras acanthicum and 

Ph. karpinskiiy from which he concludes that the top of the subzone of A.yo 

is also exposed. 

At Cumnor 10 ft. of the same dark, shaly clays with E. virgula and Aptychus 

have been seen in the north end of the pit, but they are not visible on the main 

face to the south, being there thrown down below the floor by a fault. The 

zone at this place yields numerous Saurian bones, just as at Swindon and at 

Kimeridge. Remains of Pliosaurus, Plesiosaurus, Dacosaurus (also found at 

Shotover) and Ichthyosaurus have been obtained, and also the type-specimen 

of Camptosaurus prestwichi Hulke. A. eudoxus and allied ammonites are 

tolerably abundant. 

At Rids Hill Brickyard, again, in the same clays, Dr. Pringle has obtained 

the characteristic fossils, A. eudoxus, Aptychus latus and Exogyra virgula. 

Rasenia and Pictonia Zones. 

The only section of the basal clays below the Aulacostephanus zones now 

open seems to be the old brickyard at Rids Hill, which is becoming obscure 

since being abandoned in 1911. The section was described by Prof. Morley 

Davies in 1907 and again by Dr. Pringle in 1924. 1 Immediately below the 

Aulacostephanus zone are two 1 ft. bands of creamy-weathering cementstone 

with fragments of Rasenia, enclosing 2 ft. of creamy, calcareous clay; 

below this are 8 ft. of dark grey selenitiferous clay with Rasenia stephanoides 

(Oppel), Ostrea delta, and ancestral forms of Exogyra virgula. 

At the base is what Prof. Morley Davies described as the most fossiliferous 

bed in the pit—the BRILL SERPULITE BED. It consists of an impersistent band 

of limestones or flattened doggers, up to 6 in. thick, largely composed of 

Serpulce and shells. The stone is so tough that while the smaller bivalves such 

as Cyprinids and Astarte usually spring out perfect when it is broken, the 

larger belemnites and oysters generally shiver to pieces. When the masses are 

weathered, however, a better idea of the fauna can be obtained. Serpula 

tetragona (Sow.) and the little 'CyprincC cf. cyreniformis Blake predominate, 

but Ostrea delta and other lamellibranchs also abound, 2 and Buckman has 

figured from the bed a specimen oiPrionodoceras superstes. 3 Since this ammonite 

1 1926, loc. cit., p. 74. 2 A. M. Davies, 1907, Q.J.G.S., vol. lxiii, p. 34. 

3 T.A., 1923, pi. CDXXII.


has been found in association with Pictonice in Scotland, 1 Dr. Pringle suggests 

that the Brill Serpulite Bed may possibly be a representative of the 

Pictonia bay lei zone. He detected the bed in situ for the first time in 1924, at 

the base of the Rasenia zones, and he therefore considered the Serpulite Bed 

the basal bed of the Kimeridge Clay. Below were exposed 14 ft. of black 

selenitiferous clay probably belonging to the upper part of the Ampthill Clay 

(Upper Calcareous Grit-equivalent). 

In no other exposure near Oxford has so much as a suggestion of the 

Pictonia zone been found. As mentioned in the last chapter, during the reconstruction 

of the London road in 1925, Dr. Pringle saw a deep trench east 

of Shotover Lodge, in which clays belonging to the zone of Rasenia cymodoce 

rested directly on a markedly eroded surface of the Corallian limestone. In 

the old quarry below the brickyard at the foot of Shotover Hill a similar 

section has only lately become overgrown. Phillips noted that about 15 ft. 

from the base of the clay there was a band of septaria yielding Rhactorhynchia 

inconstans, while below were layers of Ostrea delta, Exogyra nana and E. 

virgula (Sowerby's type specimens of the first two oysters came from here). 

At the base was a layer of coprolites. 2 

The non-sequence in the Oxford district denoted by this hiatus is very 

considerable, for not only is the Pictonia baylei zone missing, but also all the 

Upper Calcareous Grit and Glos Oolite Series of the Corallian (see p. 403). 

The difference between the Shotover Grit Sands or pectinatus zone at 

Shotover and at Wheatley indicates that lateral variation is likely to be considerable. 

In the Horsepath tunnel, by which the railway passes under 

Shotover Hill, and in the adjacent cuttings, the sands seem to be much thicker 

and they have at their base two bands of shelly limestone, 1-2- to 2 ft. thick and 

4 ft. apart, which run all through the cuttings. No Swindon Clay seems to be 

present. 3 A comparable section was made out by Prof. Morley Davies in 

a long field trench dug down the side of the hill near Garsington. 4 The sands 

were seen to be about 33 ft. thick and to become argillaceous towards the 

base. They were capped by a well-marked Lydite Bed, which was directly 

overlain by the green Glauconitic Series of the Portland Beds. The increased 

thickness of the sands suggests that the Swindon Clay has in this direction 

passed into sand. 

Exactly comparable sections, where the green Glauconitic Beds with their 

basal Lydite Bed rest directly on some 30 ft. of sands (the Thame Sands of 

Buckman), had been described by Fitton farther east, at Long Crendon and at 

Barley Hill, east of Thame 5 (see below). 

(c) The Thame and Aylesbury District (Hartwell Clay Area). 

In the district about Thame and Aylesbury the best sections to be obtained 

are afforded by shallow brickyards, most of which are opened in 

a sandy, greenish clay, usually more or less micaceous and glauconitic—the 

HARTWELL CLAY. 

1 S. S. Buckman, 1923, T.A., vol. iv, p. 42. 

2 J. Phillips, 1871, Geol. Oxford, p. 413. 

3 J. Pringle, 1926, loc. cit., p. 71. 

4 A. M. Davies, 1899, P.G.A, vol. xvi, p. 20. 

5 W. H. Fitton, 1836, Trans. Geol. Soc. [2], vol. iv, pp. 281-3.


The type-section is Locke's Brickyard, Hartvvell, about a mile south-west 

of Aylesbury, beside the Thame road. Almost a duplicate section was 

formerly to be seen at Webster and Cannon's (Hill's) Brickyard, on the 

Bierton Road, north-east of Aylesbury, and in Ward and Cannon's Brickyard 

at Bierton. At these places the Hartwell Clay is or was exposed to a depth of 

about 10 ft., and is directly overlain by the Upper Lydite Bed and Glauconitic 

Series of the Portland Beds. 1 As early as 1880 Hudleston called this 

lydite bed the 'basal conglomerate of the Portlands' and correlated it with the 

similar stratum at Swindon; and in the passage already quoted (on p. 448) 

written in 1896, he definitely correlated the Hartwell Clay with the Swindon 

Clay. There was at that time no certainty on this point, however, for the 

fauna had not been properly studied, and the strata below the Hartwell Clay 

were, and still remain to-day, virtually unknown. Hudleston mentioned 

a report that a sandy stratum lay between the Hartwell Clay and the lower 

shaly clays on Aylesbury Hill, but he said that the information was unreliable. 

There is thus at least an indication that the Shotover Grit Sands 

may have some representation as far east as Aylesbury. 

Concerning the stratigraphical position of the Hartwell Clay there have 

been widely divergent opinions: Blake in his paper on the Kimeridge Clay of 

England (1875) first placed it in the Lower Kimeridge, but five years later, 

probably under the influence of Hudleston, who in that year (1880) conducted 

an excursion to the district, he admitted his mistake and ascribed it to the 

Upper Kimeridge. H. B. Woodward in 1895 went to the other extreme and 

described the Hartwell Clay as part of the Portland Beds. In this he was 

probably misled by the then recent discovery that tin* Middle and Upper 

Kimeridge Clay of England were to be correlated with the Lower and Middle 

Portlandien of French geologists, but it is plain that he used the term Portland 

Beds in the English sense, not in the Continental. Apart from matters of 

nomenclature, he agreed with Hudleston, for he wrote: 2 

'There can be no question that the clay below the Portland Stone at Swindon is 

homotaxial with the Hartwell Clay, for although the Swindon Clay is not so fossiliferous 

as that at Hartwell, yet it has yielded some species, and the beds immediately 

below the Swindon Clay have yielded many fossils identical with those of the 

Hartwell Clay.' 

In recent years Dr. Neaverson has collected many ammonites from the 

Hartwell Clay and has studied them and the collections in the Aylesbury 

Museum and elsewhere, with the result that the date of the deposit has been 

settled beyond much doubt as principally pallasioides, the lower parts including 

also deposits of rotunda date. In the monograph, already mentioned, 

on the ammonites from the Aylesbury-Oxford district (1925), he has described 

and figured the following forms from the Hartwell Clay: 

3 'Aposphinctoceras' ailesburiense Neav., pi. 11, fig. 3. 

3 4 A. 1 hartwellense Neav., pi. n, fig. 4. 

3 'A.' variabile Neav., pi. 11, fig. 5. 

'Holcosphinctes 1 pallasioides Neav., pi. ill, fig. 5. 

'H.' flexicostatus Neav., pi. in, fig. 6. 

1 See W. H. Hudleston, 1880, P.G.A., vol. vi, pp. 344-52; and 1888, ibid., vol. x, pp. 166-72. 

2 1 8 9 5 , P . 223. 

3 Buckman did not consider these species congeneric with the genotype, which was chosen


while from the lower parts of the clay, obtained at a time when the brickyards 

were worked to a deeper level, he has described two representatives of the 

rotunda fauna: P. ultima (pi. 1, fig. 2) and P. inflata (pi. 11, fig. 2). 

Since the discovery, announced by Dr. F. L. Kitchin, of P. pallasioides in 

the upper part of the Swindon Clay, 1 it is evident that the Swindon Clay and 

Hartwell Clay can be closely correlated, although the greater part of the 

Swindon Clay is probably of rotunda date and represents that portion of the 

Hartwell Clay lying below the usual floor of the brickyards. At Wheatley and 

Shotover, on the other hand, the upper or pallasioides portion of the clay 

seems to have been removed in early Portland times, before the formation of 

the Upper Lydite Bed. 

Much additional information of interest might be obtained from a study of 

the lamellibranch faunas of these uppermost clays; for instance Dr. Kitchin 

finds that the most characteristic Hartwell species, Hartwellia hartwellensis 

(Sow.), recently described by him as the type of a new genus, is absolutely 

restricted to this level, although other allied species have been wrongly 

recorded under the same name from thz pectinatus and even the Virgatosphinctoides 

zones at Swindon and Shotover. 

Before leaving the subject of the Hartwell Clay, reference must be made to 

an opinion persistently held by Buckman, that the pallasioides fauna of the 

Hartwell Clay should be sought below the Shotover Grit Sands of the Oxford 

district and of Swindon. To the last he maintained that the Survey and 

Dr. Neaverson were wrong in their correlations. 

'There is no objection taken', he wrote in August 1926, 2 'to the correlation of the 

rotunda zone of Chapman's Pool with the Swindon Clay and with the Littleworth 

Lydite Clay; but when they also correlate these deposits with the Hartwell Clay of 

Hartwell, near Aylesbury, serious protest must be made; because the stratigraphical 

sequence of the beds is quite opposed to it. . . . The likeness of the Ammonoids of 

the Hartwell Clay and of Chapman's Pool is admitted; but it is a deceptive likeness.' 

Again, in December 1926, 3 he wrote: 

'There are at Swindon, below the pectinatus beds, a thick series of sands (Lower 

Cemetery Beds) above some feet of clay, whose ammonoid faunas are unknown: 

these beds are where the Hartwell Clay faunas should be sought. . . . There is little 

to be gained in reiterating statements of correlation without figuring the ammonoid 

evidence. I have figured such evidence for the correlations of the beds concerned.' 

Any one reading these passages without knowing the history of the controversy 

might be led to believe that the weight of evidence was on Buckman's 

side. In 1926, however, at the meeting of the British Association at Oxford, 

Buckman read a paper upon the position of the Hartwell Clay. The paper 

was never published and so, in the interests of truth, a word of explanation 

may be timely. 

Cross-questioning by Dr. Pringle elicited the information that the critical 

ammonites from Long Crendon, upon which the correlations depended, had 

by Neaverson as A. decipiensy nom. nov. for the specimen figured by Miss Healey as Olcostephanus 

pallasianus in 1904, from the Swindon Clay of Chippinghurst, near Chiselhampton, 

Oxon. See T.A., vol. vi, 1926, p. 25 (where references are given). Dr. Spath, on the other 

hand, considers not only all these but also the allied genera Holcosphinctes and Episphinctoceras 

Neaverson synonymous with Pavlovia (1931, loc. cit., pp. 470-1). 

1 F. L. Kitchin, 1926, Ann. Mag. Nat. Hist. [9], vol. xviii, p. 452. 

2 T.A., vol. vi, p. 27. 3 ibid., p. 40.


not been dug up either by Buckman or in his sight, but had been purchased 

long afterwards from workmen, who had also worked in the pits at Hartwell 

and Brill. They had, therefore, probably never come from Crendon at all, 

but from the Hartwell Clay of Hartwell. 

The sections at Long Crendon, on the hill leading down towards Thame 

(Barrel Hill), were described by Fitton in his classic memoir on the Strata 

below the Chalk, 1 and were re-examined in 1898 by Prof. Morley Davies, 

who confirmed Fitton's sequence. 2 Underlying the typical Portland Limestones 

are the usual Glauconitic Beds, with the Upper Lydite Bed at the base. 

Below come 30 ft. 3 of predominantly sandy strata 'with much clayey material 

in some of the beds' according to Morley Davies, and these rest in turn upon 

clay, which was formerly dug in the old brickyard near the foot of the hill. 

Nothing is now visible in the brickyard, the adjoining sand-pit has been 

filled up with rubbish, and the road-cutting is overgrown. 

Similar conditions—Lydite Bed resting directly on sands, as at Garsington 

—were proved by Morley Davies in drainage excavations in Thame, and 

Fitton described the Glauconitic Beds resting directly on 30 ft. of sands at 

Barley Hill, east of Thame. Here the sand (Buckman called it Thame Sands) 

contained 'nodules of great size scattered in it irregularly', and they reminded 

Fitton of the doggers in the Shotover Grit Sands at Shotover. 4 

Buckman admitted the approximate contemporaneity of at least a part of 

the Thame Sands and the Shotover Grit Sands, but his point of divergence 

from the view accepted by all other recent investigators lay in the belief that 

the clay below the Thame Sands in the old brickyard at Long Crendon was 

Hartwell Clay. Blake referred to it as Hartwell Clay when leading an excursion 

of the Geologists' Association to the brickyard in 1893, but his 

contribution to Kimeridgian stratigraphy was never profound, and he gave 

no reasons for the opinion. Prof. Morley Davies also visited the brickyard 

while it was still in work, but he found no fossils, and a workman 'although he 

certainly knew what fossils were' informed him that none were found. 

To settle the matter an excavation was made in the floor of the old brickyard 

at Long Crendon, and in the presence of Messrs. Buckman, Pringle and 

Chatwin, Dr. Pringle informs me, the workmen unearthed some ammonites 

typical of the Virgatosphinctoides zones, but nothing at all suggestive of 

Hartwell Clay. About 6 ft. below the floor of the pit appeared the Exogyra 

virgula clays. 

The true explanation may be that, northward and eastward from Garsington 

to Shotover Brickyard and Wheatley, the upper part of the sands below 

the Upper Lydite Bed passes into the sandy Swindon Clay, and again that 

northward and eastward from Thame and Long Crendon to Brill and 

Hartwell it passes into the sandy Hartwell Clay. H. B. Woodward appears 

to have been believed in such a change of facies, for he wrote: 5 

'It is evident that the "sands of the Lower Portland Beds" [i.e. Thame Sands] are 

gradually replaced by clay as we proceed northwards [from Long Crendon]. At 

Brill, beneath the lydite-bed, there is 3 ft. of brown and greenish sand, which passes 

1 1836, Trans. Geol. Soc. [2], vol. iv, pp. 281-2. 

2 A. M. Davies, 1899, P.G.A., vol. xvi, p. 21. 

3 Buckman's measurements make the sands 80 ft. (T.A., vol. vi, p. 36), but this thickness 

is improbable. 

4 W. H. Fitton, 1836, loc. cit., p. 283. s ^95, J.R.B., p. 225.

KIMERIDGE CLAY: THE FENS 467 

down gradually into stiff blue clay, yielding Ammonites biplex, Thracia, &c., and is 

not separable from the Kimeridge Clay.' 

Prof. Davies expressed the same view somewhat differently,- as follows: 

'If we consider the . . . beds below the Pebble Bed [Upper Lydite j|ed] we can trace 

a gradual transition, the clayey facies gradually rising from west tcteast. From the 

39 ft. of pure sands with limestone at Garsington, we pass through ft. of more 

or less clayey sands of Long Crendon [Thame Sands] to the sandy clay^f Dadbrook 

Hill and Hartwell [Hartwell Clay].' 1 

An alternative explanation, suggested and preferred by Dr. Kitchin, is that 

at Garsington, Thame and Long Crendon the non-sequence below the Upper 

Lydite Bed is greater than at the other places, and the Hartwell Clay has been 

removed by erosion, leaving the Upper Lydite Bed resting on Shotover Grit 

Sands. 2 If this view is correct the whole of the Thame Sands should one day 

be found to contain the pectinatus fauna. 

III. THE FENS: CAMBRIDGE AND NORFOLK 

After a gap of about 32 miles the Kimeridge Clay gradually emerges once 

more from beneath the Lower Greensand at Great Gransden, 10 miles west of 

Cambridge. 3 The outcrop remains narrow until due north of Cambridge, 

where it spreads out to a great width and is lost beneath the Fens. The 

eastern half of the Fens is floored by the Kimeridge Clay, which rises through 

the superficial deposits here and there as low, straggling 'islands'. The 

largest is the Isle of Ely, with its cappings of Lower Greensand, and other 

large islands have determined the sites of Chatteris and March. In Norman 

times the artificial causeways were the only means of communication between 

these isolated tracts and the mainland. 

The area was studied principally by T. Roberts of Cambridge, previous 

to the year 1886, 4 but much additional information has been obtained from 

borings made during and since the Great War. 

The maximum thickness of the Kimeridge Clay was estimated by Roberts 

to be 142 ft., this figure being arrived at by piecing together a composite 

section from the principal brick-pits in Cambridgeshire. He was in doubt, 

however, about 20 ft. of clays, which he considered he might have included 

twice, at Haddenham and at Littleport. In 1920 three boreholes were drilled 

in the Fens east of Southery, just over the border of Norfolk, and the results 

were published by Dr. J. Pringle. 5 The whole of the Kimeridge Clay was 

pierced in two of the borings, capped by Lower Greensand, and the total 

thickness was 121 ft. in one boring and 125 ft. in the other. 

Pleistocene or Lower Cretaceous deposits rest unconformably on the clay. 

The Sandringham Sands of the Lower Greensand have at their junction with 

it a pebble-bed containing phosphatic nodules. The thinness of the Kimeridge 

Clay, however, is not due primarily to truncation of its upper zones by 

1 1899, P.G.A., vol. xvi, p. 25. 2 F. L. Kitchin, 1932, in lit. 

3 The Pictonia zone may appear sporadically much earlier, especially about Ampthill, where 

Perisphinctes variocostatus (Buckland) is said to have been found in clay grouped as Ampthill 

Clay, and according to Buckman indicates basal Kimeridgian. At Sandy, however, the 

Kimeridge Clay is entirely overstepped and Lower Greensand rests on basal Corallian. 

4 T. Roberts, 1892, Jurassic Rocks of Cambridge, pp. 61-76. 



the pre-Cretaceous denudation, but to piecemeal attenuation of its component 

parts, as in Oxfordshire. In the Southery borings all the main zones were 

detected. The formation consists of dark clays with occasional thin bands of 

cementstone and some brown and greenish-brown oil-shales, just as in the 

South of England. The thinness would seem, therefore, to be due mainly to 

slow deposition. 

According to Dr. Pringle, the basement-bed of the Sandringham Sands 

rests upon some part of the rotunda zone, for within 4 ft. of the top of the clay 

fragments of an ammonite were found which compare with some of those 

abounding in the rotunda zone at Chapman's Pool. Some better-preserved 

examples were found in another boring at King's Lynn. 

Only 13 ft. below this horizon at Southery was encountered a shale, 8 in. to 

1 ft. thick, crowded with the pyritized radial plates of Saccocoma, associated 

with fish teeth. These crinoid remains occur in Dorset, as has been stated, 

on the horizon of the Kimeridge Oil-Shale. Twelve feet below the Saccocoma 

band was a cementstone, which, since it marked the lower limit of Modiola 

autissiodorensis and the upper limit of Exogyra virgula, Dr. Pringle correlated 

with the Yellow Ledge Stone Band of Kimeridge. 

The Gravesia zones were not proved palaeontologically, but there was room 

for them in the borings, for 30 ft. below the cementstone the Aulacostephanus 

pseudomutabilis zone was proved by a layer of Amosboceras krausei (Salf.). 

The Pararasenia mutabilis fauna was represented by Pararasenia desmonota 

(Oppel), about 18 ft. above the base of the Kimeridge Clay at Southery, while 

Rasenia stephanoides was obtained from several borings near King's Lynn. 

At the base were 6 ft. of grey limy clay with fragments of smooth-whorled 

ammonites, identified with some hesitation as Pictonice. 

Thus the bulk of the formation from the rotunda zone downwards seems 

to be represented in the Fenland, and a re-examination of the brickyards of 

Cambridgeshire on modern palaeontological lines might yield much new 

information about the several zones, their thicknesses and faunas. 

The interpretation of Roberts's descriptions in the light of the borings is 

a task which could only be undertaken after a study of his fossils and other 

material, and detailed collecting from the pits. 

In the first place it is evident that nearly all the sections described by him 

fall in the Lower Kimeridge Clay, below the level of the Yellow Ledge Stone 

Band. The opinion formerly held, that at the Roslyn (or Roswell) Pit, 1 mile 

north-east of Ely, some 8 ft. of paper-shales and clays with Orbiculoidea 

latissima are above the limit of Exogyra virgula, is not sustained by recent 

work. Dr. Kitchin and Dr. Pringle inform me that they have carefully 

examined the highest beds there and have found that their position is not 

above the zone of Aulacostephanus pseudomutabilis. The principal Exogyra 

virgula beds, which (Roberts noted) are also characterized by abundance of 

Aptychus latus at a certain level, we may identify with little hesitation as 

belonging to the Aulacostephanus zones. At the Roslyn Pit these beds 

occupy about 26 ft., and the main E. virgula bed is within 3 ft. of the top. 

Roberts used as zonal index of these Aptychus and virgula beds the comprehensive 

1 Ammonites alternans\ 

The lowest 4 ft. of clay and shale exposed from time to time in the Roslyn 

Pit are marked by a band crowded with Astarte supracorallina, and from this


level Dr. Pringle has recorded Pararasenia desmonota (Oppel), characteristic 

of the mutabilis zone. 1 Normally the floor of the pit is under water. 

The downward continuation was believed by Roberts to be represented in 

three clay-pits at Littleport. If these three pits do not overlap more than 

Roberts supposed, the Astarte supracorallina level is underlain by some 40 ft. 

of clay; but this needs substantiating by more intensive collecting. 

The basement-beds were described in a brick-field half a mile west of 

Haddenham Railway Station, and in several temporary exposures near the 

west side of the outcrop. They always contain layers of Ostrea delta, and 

at the base a band of phosphatic nodules, thought to be coprolites. Where 

the base of the Kimeridge Clay rests upon the coral rag of Upware there is 

reported to be at the junction a layer of broken and rolled fragments of coral, 

but the clay is there unfossiliferous. The abundance of Ostrea delta and 

the layer of phosphatic nodules are said to be otherwise of widespread 

occurrence and to provide an easily recognized guide in mapping the 

junction of Kimeridge and Ampthill Clays. They recall the Corallian- 

Kimeridge junction at Shotover, Oxford. 

IV. LINCOLNSHIRE: FROM THE WASH TO THE HUMBER 

Beneath the Wash and the lowest tract of the surrounding Fens the 

Kimeridge Clay is totally concealed for 30 miles. On reappearing in Lincolnshire 

it has more than doubled in thickness, the accepted estimate from a 

number of borings in the south and middle of the county being 300-320 ft. 2 

The most recent boring, at Donnington on Bain, which was undertaken in 

1917 in search of oil-shale, stopped short after passing through 245 ft. of 

Kimeridge Clay, without reaching the bottom. 3 The lowest zone for which 

any fossil evidence was obtained was that of Aulacostephanus pseudomutabilis, 

at a level 66 ft. above that at which the boring was stopped. In an older boring 

at the same place the Kimeridge Clay was said to have been penetrated 

for 309 ft. 

In the north of the county the Lower Cretaceous rocks gradually overstep 

on to successively lower levels within the clay, but the overstep has never 

been investigated quantitatively. Owing both to the poverty of exposures and 

to ihe difficulty of drawing a lower boundary between the Kimeridge and the 

Ampthill Clays in the north of the county, the extent to which the various 

zones may individually or collectively attenuate is unknown. All that can at 

present be said is that the Kimeridge Clay, like the Oxford, becomes much 

thinner towards the Humber. 

The highest beds passed through beneath the Spilsby Sandstone in the 

Donnington boring were unrepresented by cores; but at 30 ft. from the top 

Dr. Pringle recognized several specimens of a finely-ribbed Perisphinctjd 

identical with some which characterize the oil-shale at Kimeridge (Subplanites?). 

Two bands of brown bituminous shale were in fact encountered 

at 21 and 30 ft. from the top. The same forms of ammonite were also recorded 

at Acre House Mine, north of Claxby. 

Perhaps to some part of the Upper Kimeridge, if not to the Aulacostephanus 

1 J. Pringle, 1923, loc. cit., p. 135. 

2 H. B. Woodward, 1904, 'Water Supply of Lines/, p. 10, Mem. Geol. Surv. 


8O4371 K K


zones, also belong about 15 ft. of paper-shales exposed in a brickyard about 

a mile west of Fulletby. 1 The bedding-planes of the shale are here crowded 

with white shells of Orbiculoidea latissima and Lucina minuscula, recalling the 

paper-shales at Ely, formerly thought to be of Upper Kimeridge date but now 

assigned to the Aulacostephanus zones. 

Certainly the majority of the sections in Lincolnshire fall within the Lower 

Kimeridge Clay. The general succession seems to be normal, consisting of 

the usual dark clays with some cementstone bands, but much work still 

remains to be done on the palaeontology. An extremely interesting feature 

is the representation of the Gravesia zones, indicated by the raising of 

specimens of supposed Gravesia in the Donnington boring from a depth of 

70 ft. below the top of the Kimeridge Clay. At 179 ft. from the top w r as found 

Aidacostepha?ius eudoxus. The absence of Exogyra virgula is remarkable, and 

seems to be a characteristic feature of the tracts north of the Wash. Bands of 

brown bituminous shale, on the other hand, occur more frequently and at 

much lower horizons than in any other part of England. They closely resemble 

the 'Kimeridge Coal 5 and give a similar yield of oil and other products, 

all strongly contaminated with sulphur. The lowest bands fall within the 

zone of Aulacostephanus pseudomutabilis. 

The beds below the Aidacostephanus zones are best known from the renowned 

brickyards of Market Rasen, the type-locality of the genus Rasenia 

where the ammonites are in beautiful iridiscent and pyritic preservation. 

The commonest species here is Rasenia cymodoce. The zone has also been 

worked at Brigg and at Horncastle, where in addition Pictonice are recorded. 

Roberts noted that Astarte supracorallina has a longer range in Lincolnshire 

than in Cambridgeshire, occurring throughout the Lower Kimeridge; and 

that 'Ammonites alternans\ which he used as a zone fossil, attains its acme at 

a lower level. (It would include C. kitchini, C.pingue, and C. cricki of Salfeld.) 2 

The basement-beds of the Kimeridge Clay were recognized by Roberts at 

Woodhall Spa, West Barkwith and North Kelsey, crowded as usual with 

Ostrea delta. 

V. THE MARKET WEIGHTON AXIS 

It is certain that the Kimeridge Clay, like the Oxford and Corallian Clays, 

becomes extremely thin on approaching the Market Weighton Axis, for in 

South Yorkshire the three together measure little more than 100 ft. in thickness. 

Owing to the lack of exposures no boundaries have been drawn between 

the three formations, but 'in a general way, the Oxford Clay may be taken as 

occupying the flatter part of the ground just above the Kellaways Rock, while 

the Kimeridge Clay forms the steep slopes beneath the Chalk escarpment 5 . 3 

Definite evidence for the presence of Kimeridge Clay is scanty, and it is 

improbable that any is present north of Drewton. Between the Humber and 

Drewton the Cretaceous rocks probably overstep all but the lowest zones, 4 

so that the full thickness is nowhere present and the effects of the Market 

1 J. F. Blake, 1875, Q.J.G.S., vol. xxxi, p. 201. 

2 Ibid., pp. 206-9; T. Roberts, 1889, Q.J.G.S., vol. xlv, pp. 551-8; H. B. Woodward, 

iSgs,J.R.B., pp. 173 -7; H* Salfeld, 1914, loc. cit., Table I, 1915, loc. cit., pi. xix, figs. 1-17. 

3 C. Fox-Strangways, 1892,J.R.B., p. 299. 

4 In a boring at Ferriby, near Hull, Red Chalk was found to rest either on the basal part 

of the Kimeridge Clay or on clays of Corallian age: J. Pringle, 1921, Sum. Prog. Geol. Surv. 

for 1920, p. 63.

KIMERIDGE CLAY: YORKSHIRE BASIN 471 

Weighton Axis upon sedimentation in Kimeridgian times will never be known 

quantitatively. 

On the north side of the Chalk Wolds the Kimeridge Clay does not appear 

at the surface until Acklam and North Grimston, a considerable distance from 

the axis, and by then the northerly thickening has already set in. 

VI. THE YORKSHIRE BASIN 

In the Yorkshire Basin the Kimeridge Clay floors the Vale of Pickering, 

bounded on the north by the rising dip-slope of the Corallian Moors and on 

the south mainly by the steep escarpment of the Chalk Wolds. Along the 

eastern part of the Vale, where the southern boundary is so formed by the 

overstepping Chalk and subjacent Speeton Clay, the structure is in essential 

features the same as that of the Vale of the White Horse, where the Gault 

protruding from the foot of the Downs is in contact with the Kimeridge Clay. 

In the western part of the Vale of Pickering the clay area is bounded on the 

south by the Corallian rocks of the Howardian Hills, the junction being 

largely faulted (see map, p. 138). 

The greater part of the outcrop of the Kimeridge Clay, forming as it does 

the lowest tracts of the vale, is thickly covered by the alluvial deposits of the 

Pleistocene Lake Pickering, and exposures are scarce. Along the south side 

the alluvium laps up to the foot of the Wolds and the Corallian hills, covering 

the 'solid' formations to an average thickness of 90 ft. Only for a short 

distance where the Chalk escarpment turns southward, from Wintringham 

to Grimston, Birdsall and Acklam, does the Kimeridge Clay break through, 

and it is repeated in a faulted inlier south-west of Malton. Along the north 

side of the Vale outcrops are more numerous, but the consequent streams 

running down from the moors have dissected a once continuous rim of clay 

into a series of tongues and outliers. East of Brompton the clay becomes 

entirely hidden beneath the superficial deposits. 

The east end of the Vale of Pickering, where good coast-sections might 

have been expected, is completely blocked with Drift. Under Filey the surface 

of the Kimeridge Clay is below sea-level, but towards the south end of the bay 

it rises sporadically above low-tide mark and towards Speeton it forms the base 

of the cliff, beneath the slipped masses of Cretaceous clays and Chalk. The dip, 

however, is southerly and soon brings the Cretaceous rocks down to beach-level. 

The Speeton cliffs present at first sight a hopeless spectacle, a jumbled mass 

of slips, largely covered with mud. In the course of a century, however, 

geologists, chief among whom was the late G. W. Lamplugh, have watched 

the sections and, by piecing together the information obtained at different 

times when opportunities were favourable, after the beach has been swept 

clear by a storm, have succeeded in reconstructing the succession and collecting 

numerous fossils in situ. The state of the cliffs is always slowly but surely 

changing, and passes through cycles alternately favourable and unfavourable 

for collecting. The present century has so far been an unfavourable period, 

but two favourable occasions occurred in the thirties and again in the seventies 

and eighties of the last century. Of the later of these Lamplugh, who lived 

near at hand, was able to take full advantage. 1 

1 G. W. Lamplugh, 1896, Q.J.G.Svol. Iii, pp. 179-220; and 1924, Proc. Yorks. Geol. Soc., 

N.S., vol. xx, pp. 1-31.


The stratigraphical work accomplished by Lamplugh provided a sure 

foundation for palaeontological researches, which culminated a few years ago 

in the application of Dr. L. F. Spath's wide experience of Cretaceous cephalopods 

to the ammonites collected at Speeton during the past century. 1 

He was able to dispel finally the idea, already refuted two years previously 

by Dr. Kitchin and Dr. Pringle, 2 but still embodied in nearly all text-books, 

that there are at Speeton argillaceous representatives of the Portland Beds 

and 'passage-beds 5 between the Jurassic and Cretaceous. He found the 

4 Belemnites lateralis zone', containing the earliest ammonitiferous beds above 

definite Kimeridge Clay, to be well up in the Valanginian (Lower Neocomian). 

At the base of the Cretaceous is a layer of phosphatic nodules (the 

Coprolite Bed), in w r hich are embedded derived Kimeridge ammonites, and 

this Lamplugh correlated with the similar phosphatic nodule-bed at the base 

of the Spilsby Sandstone in Lincolnshire; both beds rest non-sequentially on 

the Kimeridge Clay. Lamplugh's correlation still stands, but over the whole 

region the strata immediately above the nodule-bed are now known to be of 

Neocomian date, and to be separated from the Jurassic rocks beneath by 

a long time-interval. At Speeton, according to Dr. Spath, 'there is a complete 

absence of the uppermost Kimeridgian, the whole of the Portlandian, the 

Tithonian (= Purbeckian), the Infra-Valanginian (= 'Upper Berriasian'), 

and the lowest Valanginian formations' 3 —an enormous non-sequence, but 

detected solely as the result of modern discrimination in ammonite identification. 

The Coprolite Bed, or basal conglomerate of the Cretaceous, contains, 

among other rolled ammonites, species recorded as 'Olcostephanus' and 

' Virgatites' 4 (? Virgatosphinctoides). Beneath have been seen some 40 ft. of 

dark shaly clays with compressed fossils and large septaria, but no detailed 

study of the ammonites has yet been published. Lamplugh recorded Virgatites 

sp. [? Virgatosphinctoides]. According to Danford 80 per cent, of the 

Belemnites belong to Cylindroteuthisporrectus (Phil.), as identified by Pavlow 

(? C. tornatilis Phil. sp.). s The beds are much contorted, probably as the 

result of squeezing by large masses of Drift or even by ice. The lowest levels 

exposed may sometimes be seen at low tide on the shore near Butcher Haven, 

1J miles south of Filey. They consist of pale blue shaly clay with pyritous 

nodules, overlain by dark shales with large septaria, in which Lamplugh 

collected species of Aulacostephanus. Salfeld stated that Aulacostephanus 

pseudomutabilis, A. ? yoy and also Pictonia occurred in Filey Bay, but the last 

was probably from the Drift. 6 

The middle and lower portions of the Kimeridge Clay have been exposed 

inland in some small brickyards scattered round the rim of the western end 

of the Vale of Pickering. Since the old records of ammonites when accepted 

without revision are often misleading, little can usefully be said regarding the 

1 L. F. Spath, 1924, Geol. Mag., vol. lxi, pp. 73-89. 

2 F. L. Kitchin and J. Pringle, 1922, Geol. Mag., vol. lix, p. 197. 

3 L. F. Spath, 1924, loc. cit., p. 80. 

4 H. Salfeld, 1914, loc. cit., Table I. 

5 C. G. Danford, 1906, Trans. Hull Geol. Soc., vol. vi, pt. i, pp. 1-14; and M. Lissajous, 

1925, Repertoire alph. Belemnites jurass. 

6 Isolated outcrops of shale appear from time to time in the cliffs nearer Filey, but their 

fossils prove them to be transported masses of Lias.

KIMERIDGE CLAY: YORKSHIRE BASIN 473 

representation of the various zones. The lower layers of the shales are usually 

characterized, as in other parts of England, by large numbers of Ostrea delta. 

In the Coxwold rift valley Fox-Strangways mentions that 'Ammonites biplex 

is rather abundant, and a Discina \Orbiculoidea\ occurs'. In a brickyard at 

Hildenley, Hudleston records the basement-beds with Ostrea delta, Exogyra 

nana, &c., and 'Ammonites mutabilis\ suggesting the Rasenia zones. The same 

beds were also to be seen in the brickyard at North Grimston. 1 

The total thickness of the Kimeridge Clay in the Yorkshire basin has never 

been accurately determined. Borings along the northern and western rims 

of the Vale of Pickering pass through only the lower beds. On the south 

a boring at Knapton, close under the Chalk Wolds, penetrated 500 ft. of clay 

without reaching the bottom. The cores were not critically examined, however, 

and besides the probability that some of the clays were Cretaceous, there 

is a possibility that part of the Corallian formation is there represented by an 

argillaceous development, and that the boring came to an end in a representative 

of the Ampthill Clay. South of Wass, in the Coxwold fault-valley, 

a boring proved a thickness of 400 ft. of blue shales, and there are other 

records from different parts of the county indicating from 200 to 320 ft. A 

conservative estimate of the maximum thickness could safely be made at 

400 ft. 

VII. EAST SCOTLAND 

(a) The Brora and Helmsdale District, Sutherland 

The evidence for another basin of deposition off Eastern Scotland in 

Kimeridgian times is limited to a strip of rocks along the coast, now nowhere 

more than half a mile wide. But although forming a mere selvage, they occupy 

the foreshore and low cliffs beneath the raised beaches for a distance of over 

11 miles and provide some of the most interesting and instructive Mesozoic 

sections in all Scotland (map, p. 151). 

The outcrop is widest at the south end, where the basal zones first succeed 

the Corallian formation near Kintradwell, 2 miles north of Brora, and 

gradually dwindles northward, finally running out to sea near Dun Glas, 

north-east of Helmsdale. With the disappearance of the Jurassic rocks near 

Helmsdale the railway, which has been able to follow the coast from Golspie, 

is obliged once more to turn inland. With this sign that the coastal platform 

has come to an end, the last occurrences of Kimeridgian rocks become mere 

excrescences, hanging, as it were, from the steep wall of the Helmsdale 

Granite. 

Not the least interesting features on this coast are several fine sections 

across the Ord Fault, by which the Jurassic rocks have been lowered into 

their present position. On the small headland of Dun Glas the downthrown 

rock can be seen dipping seaward at a high angle from the fault-plane, and in 

Navidale Bay a mass of sandstone belonging to the base of the Kimeridge 

series is caught up in the fault, and deceived Judd into thinking that it was 

in position above the local Kimeridgian—here probably of Gravesice date. 

At this point a throw of at least 700 ft. is therefore proved; but the fact that 

the Kimeridge Clay is now in contact with the granite suggests that the total 

throw is somewhere about 2,000 ft. 

1 C. Fox-Strangways, 1892, pp. 375~6.


Owing to almost endless repetition by small fractures and folds, and to the 

highly variable lithology of the deposits, it is well nigh impossible to describe 

a continuous section or to arrive at the total thickness by direct measurements. 

The Survey estimated at least 700 ft., but Prof. Bailey and Dr. Weir measured 

over 1,000 ft. in unbroken succession and consider the total thickness to be 

at least 1,500 ft. Even if the whole of the formation were represented, these 

figures would be great, but modern zonal study by the Survey has proved that 

the highest strata present cannot be younger than Gravesice date. 1 The whole 

of the beds therefore fall within the Lower Kimeridge Clay, below the Yellow 

Ledge Stone Band of Kimeridge Bay. 

The most remarkable feature of the sections is the presence of Boulder 

Beds intercalated in the series through almost the entire length of the outcrop 

(PI. XXII). 2 The boulders are of all sizes up to huge masses many yards in 

circumference, and most of them are sharply angular, though some are more 

or less rounded. Here and there they are intermingled with smaller wellwaterworn 

pebbles. Hugh Miller was the first to point out that the boulders 

contain fish-remains, such as Gyroptychius and Osteolepis, proving them to 

have been derived from the Old Red Sandstone. 

The boulders usually lie along definite levels, where they protrude as 

numerous ledges averaging 5 or 6 ft., but sometimes up to 50 ft., in thickness, 

separated by dark shales. The shales are puckered and squeezed down under 

them, as if the boulders had fallen on them before they became consolidated. 

Occasionally, as at Dun Glas, little or no shaly matrix separates the boulders, 

which then form great thicknesses of breccia. 

The largest of all the boulders is a huge mass of Old Red Sandstone 

popularly known as the 'Fallen Stack', measuring 150 ft. in length, 90 ft. in 

width and about 30 ft. in height. It lies on the shore, almost covered at high 

tide, a quarter of a mile south of Portgower, where it is a well-known landmark 

from the railway (see PI. XXII). As it lies on its side the bedding-planes 

in the sandstone stand vertically, giving the impression very strongly of 

a fallen erosion-pinnacle or stack, such as are common round the coasts of 

Caithness at the present day. Yet it is only the largest of many blocks in 

a boulder-bed 50 ft. thick, underlain by shales and other boulder-beds for 

hundreds of feet. 

Many theories have been put forward to account for these extraordinary 

beds. Nearly all the explanations suggested during last century involved, in 

some way or another, glacial action, whether by floating ice, glaciers, rain, 

snow and frost, or an ice-sheet. But, as Dr. Macgregor has pointed out, 

a glacial origin is discountenanced by the absence of Drift or striae, by the 

fact that the boulders are too angular and too constant in their composition, 

and finally by the fauna and flora of the intercalated shales; both are of decidedly 

warm-temperate aspect, in no way incongruous with the fauna and 

flora of the rest of the British province at that time. 

Thus we are bound to conclude that the boulders fell from a cliff, and 

moreover, a cliff composed exclusively of Old Red Sandstone; for the boulder- 

1 Part of a large ammonite found by H. B. Woodward and taken for'A. giganteus 9 and therefore 

as indicative of Portland Beds (Q.J.G.S., 1902, vol. lviii, p. 310) is now considered to be 

a Gravesia. 

2 For the best account of these beds see G. W. Lee, 1925, 'Geol. Golspie', pp. 103-13, 

Mem. Geol. Surv.

PLATE XXII 


'The Fallen Stack', Portgower, near Helmsdale. 

The bedding-planes of the Old Red Sandstone stand vertically. The scale is 

shown by a cormorant standing on the right hand end. 


Kimeridgian Boulder Bed, near Portgower, Sutherland. 

Tumbled blocks of Old Red Sandstone interbedded in Lower Kimeridge 

shales of the Aulacostephanus zones.

KIMERIDGE CLAY: EASTERN SCOTLAND 475 

beds contain no other material, although for several miles they now abut 

against granite. That part of the movements which brought up the granite 

into its present position along the Ord Fault must, therefore, have been 

mainly subsequent to the formation of the beds. 

The explanation of the boulder-beds as under-water and shore talus fallen 

from a cliff was first arrived at by H. B. Woodward in about the year 1891, 

but his conclusions remained in manuscript until 1902, 1 and it was not until 

1910 that a condensed account was published in Prof. Seward's monograph 

on the Jurassic Flora of Sutherland. The theory has been more recently elaborated 

by Dr. Macgregor in a paper entitled 'A Jurassic Shore Line', in which 

the history of previous investigation is usefully summarized. 2 It is implicit in 

this theory that, by an almost miraculous chance, modern coast-erosion and 

the Ord Fault have interacted in such a way that they have brought about a 

coincidence of the present shore with a shore of Lower Kimeridge date; and 

further, that both shores chanced to coincide with the line of the Ord Fault. 

To such a chain of coincidences there are obvious objections, and Prof. 

Bailey and Dr. Weir deny the possibility that the boulders could have fallen 

from any ordinary sea-cliff. 3 They point out in the first place that there is at 

the foot of every cliff a platform of erosion upon which the talus falls, but that 

nowhere along these eleven miles of continuous exposures has any sign of 

the necessary platform been found; instead, boulder-beds and shales alternate 

for a thickness of at least 1,000 ft., until the Corallian strata rise conformably 

from beneath. Even the 'Fallen Stack', they remark, cannot have fallen on 

its side and remained there ever since, as its popular name implies, for it has 

no base. Below it are hundreds of feet of shales and other boulder-beds, 

proving that it must have been transported. In the second place, the cliff 

would need to have been at least 1,000 ft. high and to have been sinking progressively 

as the talus collected at its foot, for the highest layers are proved by 

the associated fossils to be still of submarine origin. Alternatively, they argue, 

it was much higher and 1,000 ft. of it was all the time below sea-level; but at 

such a depth, whence came the many large blocks of reef-corals lying loose 

among the debris ? 

The facts are ingeniously explained by Prof. Bailey and Dr. Weir in a theory 

elaborated at the centenary meeting of the British Association in 1931. The 

proximity of the boulder-beds to the Ord Fault for so many miles they hold 

to be no chance coincidence, but rather an indication that the cliff from which 

the blocks fell was none other than the fault-scarp. They explain the absence 

of a platform of erosion at the foot of the cliff, and the great thickness of the 

boulder-beds and shales, by supposing that movement was already taking 

place along the fault, as it was along the Peak Fault. It is visualized as having 

lain beneath the sea, not far from the shore. On the upthrown side, towards 

the land, grew the massive corals and shallow-water lamellibranchs; on the 

downthrown side was tranquil, deep water, in which ammonites and drifted 

plant-remains became entombed in fine, muddy sediment. 

Sporadically, differential movement was renewed and the sea-bed on the 

outer side of the fault sank a step deeper, causing a seismic wave. At the same 

1 H. B. Woodward, 1902, Q.J.G.S., vol. lviii, p. 205, and p. 310. 

2 M. Macgregor, 1916, Trans. Geol. Soc. Glasgow, vol. xvi, pp. 75-85. 

3 E. B. Bailey and J. Weir, 1932, Rept. Brit. Assoc. for 1931, pp. 375 _6 «


time blocks of Old Red Sandstone of all sizes would break away from the 

submarine cliff and slide down into the muds collecting below, followed by 

a debris of corals, shells and sand torn from the upper platform by the force 

of the wave. Then all would lapse into temporary quiescence once more, 

until the next earthquake. 1 

In recent years the work of the Scottish Geological Survey has thrown 

much new light on the fauna associated with these remarkable Kimeridgian 

beds. In places they are very shelly, though usually it is difficult to obtain 

even passably unbroken specimens. The commonest fossils are oysters and 

belemnites, while Pectens, Limas, &c., abound at several horizons, with more 

or less crushed ammonites. 

The highest part of the sequence, at Navidale, north of Helmsdale, yielded 

fragmentary specimens of a large Perisphinctid, which Messrs. Kitchin and 

Pringle compare with forms occurring in the Gravesia zones. The zone 

having the widest extent of all is that of A. pseudomutabilis, and it is from this 

that most of the fossils have been procured. The commonest forms from this 

and the underlying zones are Lima concentrica (Sow.), Ctenostreon proboscideum 

(Sow.), Chlamys cf. quenstedti (Blake), Ostrea delta Smith, Exogyra 

nana, E. virgula, and various belemnites. Fragments of Ichthyosaurus and 

Pliosaurus skeletons have also been found. 

Among the most interesting components of the fauna are the large loose 

blocks of reef-coral, Isastrcea oblonga (Flem.) and rarely Sty Una alveolata 

(Goldf.), 2 which are sometimes so numerous after having been torn up during 

storms that they are collected from the beach by the inhabitants for limeburning. 

They appear to be as foreign to the muddy shales in which they are 

found as the blocks of Old Red Sandstone, and Prof. Bailey's suggestion that 

they have been swept down from a shallow-water platform on the upthrown 

side of the fault is the only explanation yet offered to account for them. This 

was the most northerly station of reef-building corals in Mesozoic Europe. 

Other conspicuous fossils, not uncommon in certain places, are Terebratula 

joassi Dav. and Rhynchonella sutherlandi Dav., neither of which has been 

found outside Sutherland. The Rhynchonella is one of the largest species 

known. Its restriction to this locality is reminiscent of the local distribution 

of several other large brachiopods in the earlier formations in England. 

The Rasenia zones both rise to the surface in the southern part of the outcrop, 

about Loth and West Garty. They consist of a hundred feet of shales, 

interlaminated with thin seams of hard fine-grained sandstone, and Buckman 

has named them the LOTH RIVER SHALES. They stand in marked contrast with 

the Aulacostephanus shales above, owing to the absence of boulders. The best 

section is to be seen in the left bank of the Loth River, beneath the railway 

bridge and in the railway cutting north of it. The Survey have obtained 

fragmentary ammonites identified by Buckman as Rasenia cf. stephanoides, R. 

cf. cymodoce, R. cf. uralensis, R. cf. circumplicatus and Amoeboceras sp.; Lima 

concentrica is also common. 3 

1 The first statement of this theory, with a fuller discussion of earlier analogues, appeared 

in E. B. Bailey and others, 1928, Journ. Geol., vol. xxxvi, pp. 577—614. 

2 J. Pringle, &c., 1930, P.G.A., vol. xli, p. 78. 

3 S. S. Buckman, 1923, T.A., vol. iv, pp. 40-4; the ammonites are so fragmentary, however, 

that the identifications are doubtful.

KIMERIDGE CLAY: EASTERN SCOTLAND 477 

Under the railway bridge the base of the Loth River Shales is seen resting 

on thick beds of white sandstone separated by black carbonaceous layers. The 

sandstone becomes less divided by black partings towards the sea, where it 

forms conspicuous buttresses of white rock beside the Loth River estuary. 

Here it seems to be entirely unfossiliferous, but a mile farther south, in the 

gorge cut by a stream named Allt na Cuile (where nearly 100 ft. are seen), 

some of the beds of sandstone are crowded with casts of fossils. 

The position of the ALLT NA CUILE SANDSTONE in the zonal table still 

remains to be settled. H. B. Woodward originally mapped it as Corallian, but 

Buckman identified Rasenia and Pictonia in it and concluded that it belongs 

to the Kimeridge Clay, and Lee accepted his conclusion. 1 More recently the 

Scottish Survey officers have reverted to Woodward's classification. 2 The 

ammonites are all small and in the form of casts, not fit for specific determination, 

but if Buckman's identifications are right there can be no question as to 

the correct position of at any rate the highest part of the sandstone, in which 

the principal fossil-bed occurs (8 to 12 ft. from the top). Lee considered, 

indeed, that part of the sandstone replaced part of the Loth River Shales 

laterally. 3 The principal members of the fauna are Rhynchonellids, which, 

in the condition of casts showing the muscle-scars, offer a field for minute 

investigation which might settle the question. The lamellibranchs, though 

principally of Corallian species, are inconclusive; more Corallian species 

occur in the Clynelish Quarry Sandstone, which is dated by its ammonites to 

the Upper Oxford Clay. Moreover, a fragment of a large Velata from near 

the base of the Allt na Cuile section, preserved in the Scottish Geological 

Survey office, Edinburgh, is definitely not of any Corallian species known in 

England. The occurrence of spines of Cidaris smithi near the base cannot be 

regarded as of any great significance, for in Dorset the spines abound on the 

borderland of the highest Upper Calcareous Grit and the lowest Kimeridge 

Clay, in the Ringstead Coral Bed (see above, p. 379). 

Not the least interesting feature of the remarkable Kimeridgian deposits of 

Sutherland is a rich and varied fossil flora. Petrified wood is found in the 

Boulder Beds and shales, and leaves and fronds occur in the shales and sandstones. 

They have been made the subject of two monographs by Prof. Seward, 

who recorded sixty-five species of plants, comprising Wealden or Upper 

Jurassic, Middle, and Lower Jurassic species. 4 

The abundance of land plants in the Kimeridge Clay of Sutherland 

testifies to the proximity of a shore-line during the time they were deposited, 

but there is no evidence to justify calling the deposits estuarine, as has often 

been done. 


The sections showing Corallian Beds at Port-an-Righ (above, p. 434) do 

not extend above that formation, but the presence of submerged Kimeridge 

Clay off-shore is proved by fossiliferous nodules which are washed up on 

the beach. From these have been obtained ammonites of several genera 

1 S. S. Buckman, 1923, T.A., vol. iv, p. 40. 

2 1930, P.G.A., vol. xii, pp. 76-7. 

3 G. W. Lee, 1925, loc. cit., p. 106. 

4 A. C. Seward, 1911-13, see bibliography. 

5 G. W. Lee, 1925, loc. cit., pp. 114-15.


characteristic of the zone of Pictonia baylei—Pictonia, Prionodoceras (several) 

and Dichotomoceras. 

Some 6 miles farther south, on the opposite side of the Cromarty Firth, a 

minute exposure of Kimeridge Clay is visible at low tide on the foreshore at 

Ethie. The beds, which are much disrupted owing to proximity to the 

boundary fault, consist of carbonaceous shales, sandstones, grits, bituminous 

shales and limestones, with fossils of the Rasenia cymodoce zone and plantremains. 

Some of the fossils are exceptionally well preserved. From this 

locality were obtained the type-specimens of Lima concentrica (Sow.), Amoeboceras 

kitchini (Salf.), A. pingue (Salf.), Cylindroteuthis obeliscus (Phil.) 1 and 

C. spicularis (Phil.), 1 as well as the types of several plants. 


The valuable researches of Mr. Malcolm MacGregor in North-east Skye, 

already referred to in Chapters XII and XIII, have revealed that Kimeridge 

Clay is present at the north end of the peninsula of Trotternish. I am indebted 

to Mr. MacGregor for very kindly communicating for this book an 

advance account of his discoveries. 

The best section is on the foreshore at Kildorais, 2 miles north-west of 

Staffin, where about 100 ft. of shales are seen between tide-marks, tilted 

almost vertically. From the lower part of the shales Mr. MacGregor obtained 

specimens of Prionodoceras and Dichotomoceras, and from the upper part 

numerous Pictonice and occasional Rasenia; and in addition a form which was 

identified in London as ? Aulacostephanus pseudomutabilis. The lower parts 

of this succession were again discovered in a quarry in the grounds of Flodigarry 

House, and also not far from the Oxford Clay exposure on the foreshore 

on the north side of Staffin Bay. 

Kimeridge Clay has also been detected by Dr. Spath, he kindly allows me to 

state in advance of publication, in the Island of Mull. He has recognized the 

presence of numerous Rasenice and Amcebocerates among a collection made 

there by the Survey and assigned by Buckman to the 'Reineckeia zone 5 

(= koenigi zone), or Kellaways Beds (see p. 371 for further particulars). 2 

The importance of these discoveries is obviously great, for they prove that 

marine deposition continued normally in the Hebridean Area as long as in 

East Scotland, and the community of fossils indicates that the two areas were 

in connexion. 

IX. KENT 3 

The concealed outcrop of the Kimeridge Clay beneath the Cretaceous 

rocks of Kent is rather wider than that of any of other Jurassic formations. 

It underlies the coast from a little south of Dover to Folkestone, at which 

place it is succeeded by the Portland Beds; maintaining a constant width of 

about 5 miles it then strikes inland in a north-westerly direction, which soon 

changes to west north-westerly. West of the railway from Canterbury to 

Ashford its boundaries have not been determined. 

The thickness increases from east to west, and the study to which the fossils 

1 Not Oxfordian species as generally supposed (e.g. in Lissajous's catalogue). 

2 L. F. Spath, 1932, Med. om Grnland, vol. lxxxvii, no. 7, p. 149 (now published). 


1923, loc. cit.

KIMERIDGE CLAY: KENT 479 

from the borings were subjected by the Survey led them to the conclusion 

that the 44 ft. of Kimeridge Clay at Dover might be represented by 138 ft. at 

Brabourne and by a still greater thickness at Pluckley, west of Ashford. The 

separation of this thickening from the effects of pre-Cretaceous erosion was 

only made possible by close attention to palaeontological zones. 

At Penshurst 622 ft. of Upper Kimeridge Clay and Portland Sand-equivalents 

were proved, although the boring was stopped before it reached the base 

of the Virgatosphinctoides zones. At Pluckley the Lower Clays exceeded 

300 ft. up to the top of the Gravesia zones, and may have been 350 ft. thick, 

so that the total maximum thickness of the Kimeridge Clay in Kent (including 

perforce the equivalents of the Portland Sand) must be close on 1,000 ft., or 

rather more than the development in Dorset. 

The highest beds were penetrated in the most westerly boring at Penshurst, 

south-west of Tonbridge, where about 250 ft. of sandy clay overlies the 

pallasioides zone. Of this about 100 ft. is believed to represent the Portland 

Sands of Dorset (including the gorei zone). 1 Palaeontological evidence as to 

the exact stratigraphical position of these highest beds is meagre. Some unidentified 

ammonites were found, likened to some from the beds above the 

pallasioides zone of Hounstout Cliff, and there were also a species of Grammatodon 

and two or three other lamellibranchs of doubtful correlative value, but 

the exact positions of these in the Hounstout sequence (p. 446) has not been 

shown. More will be said on this subject in the next chapter on the Portland 

Beds. 

At Ottinge and Brabourne the Portland Stone rests non-sequentially upon 

clays yielding ammonites believed to indicate an horizon about 300 ft. lower 

than those immediately below the stone-beds at Penshurst and Pluckley, 

namely the pallasioides or even the rotunda zone—an unconformity comparable 

with that in Wiltshire, Oxfordshire and Bucks. 

The pectinatus and Virgatosphinctoides zones (as then understood, now 

including the Subplanites zones) were proved at Pluckley and were probably 

penetrated at Brabourne and Ottinge. They consist of shaly clays as in Dorset, 

with flattened ammonites, which have been discussed at length by Messrs. 

Kitchin and Pringle, for the most part under the name 'Pseudovirgatites\ 

Associated with them, also, were numerous pyritized radial plates of Saccocoma, 

which were taken to correlate with the oil-shale of Kimeridge. According 

to Messrs. Kitchin and Pringle, Modiola (Musculus) autissiodorensis (Cott.) 

makes its appearance near the base of the zones and ranges up into the 

Portland Sand, being one of the commonest bivalves of the Upper Clays in 

Kent. Other common shells are Protocardia morinica (de Lor.), Astarte cf. 

mysis d'Orb. and Aporrhais cf. piettei (Buv.). 

The Lower Kimeridge Clay was penetrated at Brabourne, Pluckley, Lower 

Standen, Abbotscliff and Dover. Wherever it was seen, it proved to be more 

sandy and calcareous than the Upper Clay. Palaeontologically it was separable 

with equal ease by the presence of Exogyra virgula and the absence of 

Modiola autissiodor ensis. 

Near the top of the Lower Clay a fragment of Perisphinctid was found 

agreeing with P. bleicheri (de Lor.), an ammonite of the Gravesia irius zone 

near Boulogne, and other fragments have been described as possibly repre- 

1 Lamplugh, Kitchin and Pringle, 1923, loc. cit., p. 228.


senting species of Gravesia. A notable feature of this zone was a Trigonia bed 

containing abundant T. pellati Mun.-Chalm., identical with a bed in the 

Gravesia irius zone at Boulogne. 

The Aulacostephanus zones, although probably developed normally, 

yielded no ammonites, but their presence was thought to be indicated by the 

occurrence of Protocardia morinica at a considerable distance above beds with 

Rasenia. In Dorset this Protocardia makes its appearance in the Upper 

Aulacostephanus zone, that of A. pseudomutabilis, below Maple Ledge. 

Another bivalve of the same zone which occurred abundantly at Brabourne 

and Abbotscliff was Astarte ingenua de Lor. 

The Rasenia zones proved more fossiliferous, yielding at levels 10 ft-30 ft. 

above the base of the Kimeridge Clay such species as Rasenia cf. stephanoides 

(Oppel), R. [)Prorasenia) witteana (Oppel), Pararasenia desmonota (Oppel), 

Hnvoluticeras trimerus (Oppel), Physodoceras orthocera (d'Orb.), recalling the 

upper part of the Abbotsbury Iron Ore and the clay of the type-locality of 

Market Rasen. At Dover a specimen of Rasenia was found only 12 ft. below 

the Cretaceous. 

The Pictonia baylei zone cannot be more than 10-20 ft. thick and is probably 

less, since no ammonites that would prove its presence have been found. As in 

other parts of England, however, the lowest part of the Kimeridge Clay is full 

of Ostrea delta and Exogyra nana. 

POSTSCRIPT NOTE :—On the eve of going to press an important paper has come 

to hand by E. B. Bailey and J. Weir on 'Submarine Faulting in Kimmeridgian 

Times in East Sutherland', Trans. Roy. Soc. Edinburgh, vol. lvii, Dec. 1932, 

pp. 429-67. The authors elaborate their theory referred to above, pp. 475-6, 

and claim to have established the following facts: During Kimeridgian 

times a submarine fault-scarp was maintained by intermittent movement of 

the sea-floor of the Helmsdale district, while dry land existed a little to the 

north-west. The aggregate movement of the fault much exceeded 2,000 ft. 

The fault-scarp separated a comparatively shallow-water facies from a comparatively 

deep-water facies. Frequent earthquakes caused landslips along the 

scarp and spread out the debris of Old Red Sandstone in graded boulderbeds 

in a manner indicating the co-operation of tunamis ('tidal waves'); the 

movements also opened fissures in the Kimeridgian and produced a chasmbreccia 

along the fault. Analogues are pointed to in Britain, Switzerland, 

Canada, and the United States. In addition, the Gravesia zones are established 

at several localities, and the Subplanites zone is believed to exist at the northern 

extremity of the Kimeridgian outcrop.

CHAPTER XV 

PORTLAND BEDS 

STRATA. 

Zones (Plate XL). Dorset. Swindon. Bucks. 

Titanites titan and 

T. giganteus 1 

Kerberites kerberus 2 

and K. okusensis 3 

W 

Z 

0 

H 

m j 

Glaucolithites gorei 4 

and G. glaucolithus 5 | 

Provirgatites scythicusb | SAND. 

1 

1 PORTLAND 

Freestone Series 

40-50 ft. 

i ! Q 

! < Z ! , 

J l 

« 

\ o 1 

Cherty 

Series 

60-70 ft. 

Basal Shell Bed 

cu , 8 ft. 

Portland Sand 

100-20 ft. 

Creamy Limestones 

10 ft. 

Swindon 

Sand and Stone 

25 ft. 

Cockly Bed 

4ft. 

Glauconitic Beds 

3ift. 

Upper Lydite Bed 

I. THE DORSET COAST 

Creamy Limestones 

7-12 ft. 

Crendon 

Sand 

5-6 ft. 

Rubbly Limestones 

6-12 ft. 

Glauconitic Beds 

5-10 ft. 

Upper Lydite Bed. 

(a) The Isle of Purbeck 

THE Isle of Purbeck owes to the Portland Beds some of the grandest 

coastal scenery in the South of England. From Durlston Head, south 

of Swanage, westward for 6 miles to St. Alban's (or more correctly St. Aidhelm's) 

Head, the Stone Beds ascend sheer from the sea in a perpendicular wall 

of rock, unscalable, and inaccessible except by boat. Above the cliffs, the 

home of the sea-aster, the sea-campion, the samphyre and the thrift, the 

Purbeck Beds rise as grassy slopes to a level of 400 ft. 

Here the strike coincides with the coast-line and the rocks appear horizontal, 

but in reality there is a slight seaward dip from the axial anticline of the Isle 

of Purbeck. At St. Alban's Head, where the coast-line changes its direction 

to the north, the Portland Beds rise to 500 ft. and cap the precipices of Emmit 

Hill and Hounstout, their tumbled blocks forming a wild undercliff upon the 

Kimeridge Clay beneath. From Hounstout they strike inland round the 

Golden Bowl, just failing to reach the sea in the prominent hill of Swyre 

1 Genotype of Gigantites Buckman, but, according to Dr. Spath, Buckman's genera 

Gigantitesy Briar eites, and Galbanites are all synonyms of Titanites Buckman, 1921. (See 

Spath, 1931, Pal. lndica, N.S., vol. ix, p. 472.) 

2 Formerly known as the zone of Ammonites pseudogigas Blake, but replaced by Buckman 

(1926, T.A., vol. vi, p. 26) owing to his selection of a later species of the Titanites zone as 

neotype {Trophonites pseudogigas Blake sp., T.A., 1923, pi. CCCLXXXV). 

3 Named by Salfeld (1914, Neues Jahrb., Beil.-Bd. xxxvii, pp. 130, 198-200) and since 

retained by all writers as alternative zonal index. Made genotype of Kerberites by Buckman 

(T.A., 1925, pi. DLXX). 

4 Name given by Salfeld (loc. cit.) to Ammonites biplex de Loriol non Sow. (1867, pi. 11, 

figs. 3-4) and subsequently used by all writers as zonal index. (Not placed generically by 

Buckman; but see Spath 1931, loc. cit., p. 472.) 

5 Used as hemeral index by Buckman (T.A.y 1922, vol. iv, p. 26) for part of the Glauconitic 

Beds of the Thame-Aylesbury district and figured, loc. cit., pi. cccvi. 

6 See p. 491

FRESHWATER 

STEPS 

HOUNSTOUT 

CLIFF 

CHAPMAN'S 

POOL 

p i F R ST. ALBAN'S 

WEST E M M , T H , L L BOTTOM HEAD 

HILL 

— — - tftSt Alban's Head. Total distance 2 miles. Scale, vertical and horizontal, 

FIG. 80. Section 

7 S S L ' S J £ ? ? M E M - G E O L SURV " PLATES X AND X,)

PORTLAND BEDS: PURBECK COAST 483 

Head (653 ft.), and after encircling the clay tract about Kimeridge with a bold 

escarpment, fall rapidly in overhanging crags into the sea at Gad Cliff. Here 

the dip is steeply to the north, towards the thrust-fault in the Chalk, and it is 

the predominant dip throughout Purbeck (see PI. XXV and fig. 77, p. 442). 

Farther west smaller tracts of Portland Beds rise to the surface on either side 

of Lulworth Cove, forming the Mupe Rocks, the Man o' War in Man o' War 

Cove, and the base of the promontory and the famous arch at Durdle Door 

(PI. XXVIII). These last fragments are close to the thrust-fault and they are 

tilted almost vertically. 

The maximum thickness of the formation along this coast is about 220 ft., 

consisting of Portland Stone 110-20 ft. and Portland Sand about 100-20 ft. 

Since the beds are far more continuously and more extensively exposed than 

in the island from which they take their name, it is preferable to describe 

Purbeck first. 

The Portland freestone was probably quarried in Purbeck long before the 

fame of the Portland quarries became known, and it is still wrought under the 

name of Purbeck-Portland. Its powers of resisting the weather are superior 

to those of the freestone from the island. The many ancient galleries driven 

into the cliffs east of St. Alban's Head bear witness to the activities of the past. 

Most of them have been abandoned for centuries and provided safe retreats 

for smugglers. The old quarries of Tilly Whim (generally called 'caves') are 

supposed to have supplied the stone for the building of Corfe Castle, and there 

is no doubt that some of the forgotten shafts and galleries were being worked 

in the early Middle Ages, when Swanage was exporting Purbeck Marble for 

churches, not only all over England, but to all parts of Europe. 1 

The Portland Stone is divisible in Dorset into two, the Freestone Series 

above and the Cherty Series below, corresponding roughly with the Titanites 

and the Kerberites zones. 

SUMMARY OF THE PORTLAND BEDS OF PURBECK 

The cliffs between Durlston and St. Alban's Heads provide a continuous 

exposure of almost the whole of the Portland Stone Series, and it is again 

magnificently exposed in Gad Cliff, Tyneham. In spite of this, the vertical 

(and in Gad Cliff, overhanging) precipices can be studied only at a few points, 

such as Tilly Whim, Dancing Ledge, Seacombe and Winspit, where quarrying 

operations have removed the Upper or Freestone Series, leaving the worthless 

Cherty Series beneath. At the end of the last century the quarries at Winspit 

(PI.XXIII) were still in work, but they have now been deserted for some years. 

After the Great War there was a revival with modern equipment at the old 

quarries at Seacombe and St. Alban's Head, but about 1930 both of these 

ventures became derelict. Now the only locality at which work is being 

actively carried on is inland, at the Sheepsleights Quarry of the Worth Stone 

Company, in Coombe Bottom, 1 mile north-west of Worth (fig. 82). No 

waste occurs, for the principal service to which the stone is put is the making 

of macadam, and the Cherty Series is used as well as the caps and overburden 

1 In Grabau's Textbook of Geology, 1930, pp. 812-13, two photographs of Tilly Whim are 

given with the inscription 'Tilly Whim Caves: Elevated sea-caves cut by waves in horizontal 

(Jurassic) strata'. The engraving here reproduced, from Englefield's Isle of Wight (see fig. 81), 

drawn by Thomas Webster in 1811, showing the 'caves' in the making, may be of interest to 

users of that excellent text-book. 

KJ4371 L 1

FIG. 8I. Tilly Whim Caves in 1811, drawn by Thomas Webster; showing galleries being driven into the Purbeck-Portland 

Freestones, with the Cherty Series left as a ledge below. (From Englefield's Description of the . . . Isle of Wight, 1816, pi. 33.)


of the freestone. The best freestone is cut and sold for building, but only as 

a side-line. 

This extensive new quarry provides the most valuable exposure of the 

Freestone Series in Purbeck. Being worked in four stages, it affords abundant 

access to all the beds in situy a facility never enjoyed by geologists in the old 

cliffside quarries. 1 

No detailed investigation of the fossils of the numerous individual beds of 

the Portland Stone has yet been attempted. Mollusca, especially lamellibranchs, 

are abundant at almost all horizons, but owing to the hardness of the 

matrix they make unattractive material for the collector. The best-preserved 

fossils are the ammonites, but they are so large and heavy that they present 

difficulties of their own. It is essential for the investigator of the Portland 

Beds to have sufficient previous knowledge of the palaeontology to enable him 

to make identifications with accuracy in the field (though with the ammonites 

this is impossible). In the Freestone Series the ammonites seem almost 

restricted to a level near the top, where they abound, while the lamellibranchs, 

at least the common species, range through the whole Freestone Series and 

Cherty Series in about equal abundance. It is doubtful, therefore, whether 

satisfactory small palaeontological subdivisions of the Portland Beds w r ill ever 

be established. For the present it is necessary to retain the terminology of the 

quarrymen. It has at least the merits of being applicable to all the Purbeck 

quarries and of being readily understood by all who deal with the stone, while 

it can also claim the dignity of a high antiquity. 

Titanites Zone: Freestone Series, 50 ft. 

SHRIMP BED, 8-10 ft. (reaching 16 ft. on St. Alban's Head). 

White, fine-grained sublithographic limestone, like the Cream Cheese Bed 

of the Great Oolite. It derives its name from the carapaces and claws of a 

small shrimp-like Crustacean, probably of the genus Callianassa, found in it. 2 

Casts of Protocardia dissimilis, Chlamys (Camptochlamys) lamellosa and some 

other species are also common, and occasionally there appear fragmentary 

casts of coarsely-ribbed triplicate ammonites (? perhaps Glottoptychinites 

Buckman gen.). The change to the overlying Purbeck Beds is everywhere 

abrupt, though conformable, but the downward passage to the underlying 

Spangle is gradual. 

TITANITES BED (PERNA BED, BLUE BED Or SPANGLE), 10 ft. 

Greyish shelly limestone, crowded with Trigonia gibbosa, T. incurva, I sognomon 

[Perna] bouchardi, Chlamys lamellosa, Protocardia dissimilis and many 

other shells, and the source of all the ammonites obtained in the Worth quarry 

except the fragments mentioned above, in the Shrimp Bed. The ammonites, 

which are all giants, were identified with a query by Buckman as Briareites, 3 

1 Through the kindness of the management, I was personally conducted over the excavations 

by Foreman W. J. Bower, who had spent his life in the Winspit and Seacombe Quarries 

before the present opening was begun, and whose knowledge of the stone-beds of all the 

quarries in Purbeck is unrivalled. He was able to give me the correct names for the different 

beds, together with interesting information as to their qualities, uses, fossil-contents and 

development in the coastal sections. 

2 Identification kindly supplied by Mr. H. Woods from fragmentary carapace and claw 

submitted to him from Seacombe and Worth. 

3 S. S. Buckman, 1926, T.A., vol. vi, p. 35.


which Dr. Spath considers synonymous with Titanites. 1 The previou^naming 

of this important fossil-bed is so unsatisfactory that I propose to call it the 

Titanites Bed. It was explained to me in the quarry, by the undisputed 

authority, the foreman mentioned above, that the whole bed may be called 

Spangle in one place and Blue Bed in another, but that in the Worth quarry 

the highest 8 ft. is Blue Bed and the rest Spangle; but it was almost immediately 

admitted that there was little or no perceptible difference. The word 

Spangle seems to refer to the glint of the fractured surface, due to calcite or 

shells; it is purely a descriptive lithological term, used equally for the House 

Cap lower down, and it should not therefore be applied to one particular bed 

as it has been by Buckman. 2 The foreman at Worth considered this bed the 

equivalent of the Roach at Portland, in which he was in unconscious agreement 

with J. F. Blake. Blake split up the bed at St. Alban's Head into 'Roach 5 

above and 'Oolite with Perna' below. 3 Hudleston and Monckton called the 

whole bed the Perna Bed at Winspit, 4 but this designation is unsatisfactory for 

two reasons: first because the genus usually known as Perna should correctly 

be called Isognomon, and secondly because the species, /. bouchardi, is equally 

common in the lower bed of Spangle, the House Cap, and also abounds in the 

Cherty Series at much lower levels. H. B. Woodward 5 called the whole bed 

the Blue Stone, but this term is again misleading because the stone is never 

at all blue, becoming at its darkest no more than a mauvish-grey; further, in 

quarrymen's terminology there is a nice distinction between Blue Stone and 

Spangle, and the whole course is not always Blue Stone. 

In the east, at Tilly Whim, a lenticular oyster-bed develops on this horizon. 

Locally about 8 ft. of the rock is almost entirely composed of oysters, cemented 

in an intensely hard matrix but weathering out in perfect condition. The 

principal constituents are Exogyra nana (Sow.), E. thurmanni fitall., Ostrea 

expansa Sow. and Isognomon bouchardi (Oppel), with a smaller proportion of 

Lima rustica (Sow.) and Plicatula boisdini de Lor. 

PON OR POND FREESTONE, J-J\ ft. 

Good oolitic freestone, showing some false-bedding. Fossils rare. The 

origin of the name seems to have been lost, unless it is an abbreviation of 

Upon [the Chert Vein]. 

CHERT VEIN, 2-4 ft. 

This, the most easily recognized datum in all the quarries, is usually called 

the Flint Vein or Flint Stone. Blake raised the boundary of the Cherty Series 

to include it, an undesirable course which has not been followed by any 

subsequent writer. 

LISTY BED, 6-9 in. 

So called 'because it breaks easily'. Present in the cliffs but absent in the 

Worth quarry. A soft freestone. 6 

1 L. F. Spath, 1931, Pal. Indica, N.S., vol. ix, p. 472. 

2 1926, T.A., vol. vi, p. 35, misspelt Spengel. 

3 J. F. Blake, 1880, Q.J.G.S., vol. xxxvi, p. 194. 

4 1910, P.G.A., vol. xxi, p. 514 and several earlier excursions. 

5 1895, J.fl.B., p. 190. 

6 Misspelt Lisky Bed by Buckman, loc. cit., p. 35. Apparently the Nist Bed of H. B. 

Woodward, 1895, JR.B., p. 190, perhaps so recorded in error, as the Worth foreman and his


HOUSE CAP, 8 ft. 

Greyish coarse limestone, like the Titanites Bed and also called a Spangle, 

but on the whole less shelly. A 6-in. shelly vein runs through it at Worth 

about 2\ ft. from the top, and the lower part is conspicuously shelly at Tilly 

Whim. The fossils seem to be the same, except that at Worth ammonites are 

absent; but at Winspit Woodward recorded 4 Ammonitesgiganteus\ Trigonice 

predominate. 

Fig. 82. Section of the Portland Freestone Series at Sheepsleights 

Quarry, Worth Stone Quarries, 1 mile north-west 

of Worth Matravers. 

UNDER PICKING CAP, 2-3 ft. 

Hard freestone, which had to be blasted in the old cliff quarries, locally 

called Spangle. Rarely large ammonites were found in it at Winspit, but not 

at Worth. 

UNDER OR BOTTOM FREESTONE, 8-11 ft. 

Fine cream-coloured oolite, an easily-worked freestone of excellent quality, 

men had never heard the name. At least as early as 1863 the bed immediately underlying the 

Chert Vein was called the Listy Bed (see a section at Seacombe in Hutchins's History of 

Dorset, 3rd ed., vol. i, p. 687).


with few fossils. This is the bed which was principally mined at all the 

quarries from Tilly Whim to St. Alban's Head. The numerous 'caves' are 

adit galleries driven into it, the 'caps' forming the roofs and the Cherty Series 

the floors (see fig. 81, and footnote on p. 483). 

Towards the west most of the Freestone Series dies out. Hudleston pointed 

out that in Gad Cliff and Worbarrow Tout the Shrimp Bed and Titanites Bed 

are well developed, but that they rest directly upon the Cherty Series. 1 It 

remains to be proved whether the Pond and Under Freestones and intervening 

Cap disappear or merely lose their character and become cherty. 

Kerberites Zone: Cherty Series, 60-70 ft. 

The Cherty Series forms the lower part of the cliffs east of St. Alban's 

Head and the vertical capping to the higher cliffs to the west, at Emmit Hill 

and Hounstout. So far it has defied subdivision and it has the distinction of 

being one of the thickest masses of unsubdivided rock remaining in the English 

Jurassic System. It consists throughout of intensely hard brown limestone 

with numerous impersistent veins and nodules of dark chert. It can be easily 

studied at Tilly Whim, Dancing Ledge, Seacombe, Winspit and St. Alban's 

Head. At Dancing Ledge one of the thick courses of hard stone forms the 

ledge up which the waves dance, and the surface is studded with giant 

ammonites. 

The upper part of the series is poorly fossiliferous, but the middle and 

lower parts are often quite shelly, and some of the courses are largely composed 

of Serpula gordialis. The limestone is so hard that collecting is difficult, 

but Isognomon bouchardi, Chlamys lamellosa and some of the other familiar 

shells may usually be seen. Blake recognized in 1880 that the ammonites 

differed from those found in the Freestone Series, signifying the difference 

by calling them 'A. boloniensis de Lor.' Although they abound on the surface 

of some of the ledges washed by the sea and upon the fallen blocks beneath 

the cliffs west of St. Alban's Head and under Hounstout, their characters are 

still but little known. The reason for this is that the beds have never been 

quarried and in the natural exposures it is almost impossible to detach specimens 

from their matrix, while those visible in situ are always too much 

weathered for certain identification. In 1931, however, the Worth Stone Co. 

started quarrying the Cherty Series at Worth for breaking up to make 

macadam, and so it may be hoped that some of the ammonites will be 

obtained. At present our knowledge is restricted almost entirely to a few 

specimens collected in the Basal Shell Bed of the Isle of Portland (to be 

described later, below, p. 496). 

Although Blake spoke of a Basal Shell Bed in his record of the section of 

St. Alban's Head, 2 no such bed has been detected by subsequent investigators, 

or seems to exist at this horizon in Purbeck; the shells are rather 

distributed through the lower portions of the Cherty Series instead of being 

concentrated in one particular bed as at Portland. In consequence the 

boundary between the Cherty Series and the Portland Sands beneath is less 

easy to define. The best accessible section is at the point of St. Alban's Head: 

here there is a perfect gradation downward through sandy and cherty 

1 W. H. Hudleston, 1896, P.G.A., vol. xiv, p. 319. 

2 J. F. Blake, 1880, loc. cit., p. 194.

PLATE XVIII 


Winspit Quarry, near Worth Matravers, Dorset. 

Photo. 

Portland Freestones in upper part of cliff quarried back, and Cherty Series left 

in lower part of cliff. PB = Purbeck Beds; SB = Shrimp Bed; TB = Titanites 

Bed; F = Portland Freestones and Chert Vein. The vertical cliffs of Portland 

Stone are continued in the distance, surmounted by a slope of Lower and 

Middle Purbeck Beds. 

Dancing Ledge Quarry, near Langton Matravers. 

Galleries have been driven into the Freestone behind, at a lower level. 

W.J. A.

PLATE XXII 


Swyre Head, Hounstout Cliff and Emmit Hill, seen from St. Alban's Head. 

The dip in the foreground is Pier Bottom, the next Chapman's Pool, the next 

Egmont Bay, below Encombe, with Freshwater Steps at the point where the 

grass almost reaches the sea. 


Hounstout Cliff and Emmit Hill. 

On Emmit Hill PB = The Parallel Bands; St.AHM = St. Alban's Head 

Marls; WCB - The White Cementstone; EHM = Emmit Hill Marls. The 

Massive Bed (base of the Portland Sand) crops out at the foot of the bank, 

below the photographer.


limestone and calcareous cherty sandstone to sandstone without chert but 

with honeycomb weathering, denoting that lime, formerly present, has been 

leached out. To draw the boundary at the downward limit of either lime or 

chert is unsatisfactory, and at present evidence is insufficient for the marking 

of any palaeontological division. The difficulty is illustrated by the recent 

penological study of the Portland Sands by Mr. M. P. Latter, who fixed no 

definite upper boundary to the Sands and began his descriptions of sections 

at different levels in localities so close together as St. Alban's Head and Emmit 

Hill. 1 In short, wherever we choose our boundary, we cannot avoid grouping 

either sandy beds with the Cherty Series or cherty beds with the Sands. At 

the junction are 24 ft. of grey and yellow sandstone, weathering with honeycomb 

structure, the upper half very cherty and sandy, the lower half free from 

chert (see fig. 83). I follow Hudleston 2 and Sir A. Strahan 3 in grouping 

these beds with the Cherty Series of the Portland Stone rather than with the 

Portland Sand. 

Glaucolithites Zone: Portland Sand, 100-20 ft. 

The Portland Sand was first so named by Fitton, 4 who described Emmit 

Hill, the steep cliff on the west side of St. Alban's Head (PI. XXIV) as the 

typical section. There is hereabouts a complete and almost continuous 

exposure from the point of St. Alban's Head to Chapman's Pool and again 

in Hounstout Cliff (fig. 80). At first sight 'Sand' seems a misnomer, for the 

series consists rather of grey and black sandy marls, with bands of sandstone 

and sandy cementstone. The same applies to the Isle of Portland. North of 

Weymouth, however, the proportion of sand is much higher, and there are in 

places up to 40 ft. of yellow sand; but even in Purbeck and Portland there is 

more than is at first sight apparent, for owing to its black colour and the 

admixture with marl, the sand escapes notice. 

In the cliffs of the type-locality the beds fall into several well-defined subdivisions, 

marked off by prominent bands of cementstone or sandstone, 

distinctly traceable from end to end of the exposures. To provide a framework 

for palaeontological investigations in the future it is essential that these 

thick subdivisions should have names, and accordingly some of them are here 

named for the first time. 

Buckman introduced two major subdivisions, a Cementstone Series above 

and a Sandy Series below, 5 but his interpretation of the lower boundary of 

the formation was different from that accepted here, and his Cementstone 

Series is almost exactly synonymous with the Portland Sand as now understood. 

All but the highest 5 ft. (the Massive Bed) of his Sandy Series is here 

classed as Kimeridge Clay, following Strahan, Cox, Latter and probably 

Fitton (see above, p. 446, where it is named the Hounstout Marl). 

THE PARALLEL BANDS, 23 ft. 

The most conspicuous strata in Hounstout, Emmit Hill and St. Alban's 

Head cliffs, remarked on by all observers, are two parallel thick bands of 

1 M. P. Latter, 1926, P.G.A., vol. xxxvii, pp. 76-7. 

2 W. H. Hudleston, 1882, P.G.A.y vol. vii, p. 385. 

3 A. Strahan, 1898, 'Geol. Isle of Purbeck', p. 67, Mem. Geol. Surv. 

4 W. H. Fitton, 1836, Trans. Geol. Soc. [a], vol. iv, pp. 211-12. 

5 S. S. Buckman, 1926, T.A., vol. vi, p. 34.


sandstone or sandy cementstone, which run from one end of the sections 

to the other without perceptible change. Both Blake and Buckman (and 

Hudleston and Strahan by implication) 

LIMESTONES 

CHERTY SANO 

CALCAREOUS 

SANDSTON E 

CALCAREOU5 

;ANO5TONE 

1 took these bands as marking the 

top of the Portland Sand, and since here, at the type-locality, they provide the 

only obvious summit to a division admittedly of arbitrary boundaries, it is as 

well to make use of them. Buckman and Strahan gave no thickness, but 

according to my own measurements 

and to those of Mr. 

Latter they measure in all about 

23 ft. 2 —Upper 6J~7 ft.; Lower 

10 ft.; intervening beds 5-6 ft. 

Under St. Alban's Head, 9 

in. below the top of the Upper 

Parallel Band, there is a noticeably 

even and persistent parting, 

which may indicate a physical 

break. The highest 9 in. 

form a separate bed of hard 

sandstone, above which is a 

dark shaly layer, merging up 

into the grey sandstones. A 

convenient position at which to 

draw the top of the Portland 

Sand would be at this persistent 

parting or eroded surface (fig. 

> PARALLEL 

5T. ALBAN 5 HEAO 

MARLS 

83). 

> FT - The two chief Parallel Bands 

are separated by light chalky 

shales with two white layers, 

and in the lower part of the 

chalky shales there is a thinner 

hard band (1 ft. 6 in.) as persistent 

as the other two and 

FIG. 83. Section in the cliff under the west side of St. forming a Middle Parallel Band, 

Alban's Head, at the junction of the Cherty Series with conspicuous from St. Albans 

the Portland Sand. The arbitrary boundary is taken Head to Hounstout (fie:. 8? and 

at the top of the Parallel Bands. pj XXIV) 

Concerning the palaeontology of the Parallel Bands everything still remains 

to be discovered. Blake speaks of *Ammonites biplex' as abundant, a record 

that has not so far been interpreted. 

1 'The base of the Portland Stone, however, can be seen round nearly the whole headland 

[St. Alban's] and under Emmit Hill also; it contains not only an abundance of chert-nodules, 

but so much sand that it may be described as a calcareous sandstone' (Strahan, 1898, loc. cit., 

p. 67). See also Hudleston (1882, P.G.A., vol. vii, p. 385), 'the bare slopes of Portland Sand 

are seen to be surmounted by the cherty calcgrits which form the base of the Portland Stone 

capping the precipices of Emmit Hill'. The 'cherty calcgrits' and 'calcareous sandstone' 

are the sandy base of the Cherty Series immediately above the Parallel Bands, referred to 

on p. 489. 

2 Blake gave a thickness of 39 ft., but how this was arrived at is not clear. My own measurements 

and Mr. Latter's, although made quite independently, agreed within 1 ft. See M. P. 

Latter, 1926, loc. cit., pp. 76-7.


ST. ALBAN'S HEAD MARLS, 40-45 ft. 

Below the Parallel Bands are 40-45 ft. of grey sandy marls and marly sands 

with thin bands and nodules of cementstone, all poorly fossiliferous. These 

and the underlying marly and sandy beds have not hitherto been named. 

THE WHITE CEMENTSTONE BAND, 2 ft. 

A conspicuous band of light-grey to whitish cementstone, 2 ft. thick, is 

persistent in all the cliff's, and Buckman named it the White Cementstone, 

recording and figuring from it the Behemothan ammonite Leucopetrites 

ccementarins, found by Mr. C. H. Waddington. 1 The bed breaks with a conchoidal 

fracture and the broken surfaces often show red staining. It contains 

casts of Thracia depressa (Sow.), Pleuromya tellina Ag. and 'Area" foetida Cox., 

in places abundantly, especially in the lower part. 2 

EMMIT HILL MARLS, 30-40 ft. 

Below the White Cementstone are three ill-defined bands of partly indurated, 

blackish, shaly marl or sandy shale, in all 12 ft. thick, containing 

abundant crushed casts of Thracia, Pleuromya, &c. Below this again, and 

distinguished only by being less indurated, are some 25 ft. of blue or blueblack 

sandy and partly shaly marls, with numerous thin bands of cementstone. 

Since all these are still in need of a name I propose to call them the 

Emmit Hill Marls, after the type-locality of the Portland Sand, where they 

are well exposed and thickest. According to Mr. Latter's measurements they 

are 39 ft. thick at Emmit Hill, 38 ft. at St. Alban's Head, and 30 ft. at Hounstout. 

3 Dr. Spath informs me that he believes a number of the fragments of 

Provirgatites of the scythicus group collected by him to have fallen from these 

beds. 

THE MASSIVE BED, 5-6 ft. 

The Massive Bed, so named by Buckman, 4 has already been referred to at 

some length (above, pp. 445-6). It is a prominent band of hard, blue-centred, 

brown-weathering, shaly to rubbly, calcareous sandstone, which forms an 

easily-recognized feature about 50 ft. above the old road leading round the 

face of Hounstout Cliff. Palaeontologically it has proved, owing to the researches 

of Messrs. Waddington and Buckman, of great interest. It contains 

in places an abundance of a small rugose variety of Exogyra nanay recalling 

the Exogyra Bed of the Isle of Portland, associated with crushed specimens of 

Rhynchonella portlandica Blake. Of paramount importance, however, are the 

ammonites. Buckman 5 was the first to identify some of these with the Russian 

Provirgatites scythicus (Michalski) (see above, p. 445); and since a fairly large 

number of fragments have since been found, it seems to be indicated that we 

place the Massive Bed and Emmit Hill Marls in the scythicus zone, already 

recognized in Germany (PI. XL, fig. 3). 

The Massive Bed was selected by Sir A. Strahan 6 as the arbitrary base of 

1 S. S. Buckman, 1926, T.A., p. 35, pi. DCLXXVII. 

a It seems likely that this is Blake's Bed 13 (cementstone with abundant Thracia, 2 ft.) 

(Q.J.G.S., 1880, p. 195). It is Latter's Bed 6 at St. Alban's Head and Emmit Hill and Bed 4 

at Hounstout (P.G.A., 1926, pp. 76-8). 

3 Latter's Beds 3,4, 5 (loc. cit., pp. 76-7) and 3 (p. 78); Blake's Bed 12 (thickness 30 ft.). 

4 1926, T.A., pp. 31-3. 5 Ibid., pp. 32-3, pis. DCLXXV, DCXCIII. 

6 1898, loc. cit., p. 62.


the Portland Sand, a selection accepted by Messrs. Kitchin and Pringle, by 

Latter 1 and by Cox. 2 The thickness thus assigned to the Portland Sand, if 

the Parallel Bands are taken as the top, is about 100 ft., whereas Fitton's 

original estimate was 120-140 ft. It seems likely, however, that Fitton 

included in the sands the 24 ft. of sandstone above the Parallel Bands, the 

upper part of which, as mentioned above (p. 489) contains chert. Sir A. 

Strahan's estimate of the thickness of the Portland Sand was 100-120 ft., with 

which the classification here adopted agrees, and he certainly included the 

sandstones in question w T ith the Cherty Series of the Portland Stone. 3 

The Geological Survey of 1855 mapped an indefinite line in the sandy clays 

about 40-50 ft. below the Massive Bed, and in this they were followed 

by H. B. Woodward, who estimated the thickness of the Portland Sand at 

170 ft. or 130-70 ft.; 4 and more recently Buckman also has followed suit. 

Blake preferred a line 70 ft. lower still, giving the Portland Sands 244 ft., 5 but 

w r ith this no authors have agreed. 

(b) The Isle of Portland 

The Portland Beds of the Isle of Portland bear a greater resemblance to 

those of Eastern Purbeck than to those of Western Purbeck anywhere west 

of Kimeridge, or to their continuation north of Weymouth. The Stone Beds 

are divisible into a Freestone Series above and a Cherty Series below, and 

the Sands consist predominantly of argillaceous sands and cementstones 

rather than true sands. The details, however, differ considerably, rendering 

refined correlations uncertain. 

The Isle of Portland represents but a small fragment of the southern limb 

of the Weymouth Anticline. It provides a sample of the great tract of country 

which formerly lay beyond the present coast-line of Dorset—a limestone 

upland of grassy downs like the Cotswolds, useful for sheep-grazing and 

corn-growing had it not nearly all been destroyed by the inroads of the sea. 

The island is a gently-tilted plateau, completely surrounded by cliffs of 

Portland Stone, the surface 'so destitute of Wood and Fuell that the inhabitants 

are glad to burne their Cowe Dung, being first dried against the 

Stone Walls, with which their Grounds are enclosed altogether 5 , as Coker 

tells us. 6 At the north end the cliffs rise to 495 ft., above a tumbled undercliff 

of fallen blocks lodged on the Kimeridge Clay, as at Hounstout and St. 

Alban's Head; towards the south end or Bill they sink gently into the sea. 

So extensive have been the quarrying operations of the last two centuries, 

however, that most of the Freestone Series has been removed from the cliffs, 

while vast tips of debris have built up a curtain round the greater part of the 

north, east and west sides of the island. The east side has in addition been 

much obscured by landslips, due to the heavy stone-beds foundering upon 

the clay slopes beneath. It is only the magnificent West Weare Cliffs that 

give tolerably clear and accessible sections of the Portland Sand and Cherty 

Series at the present day (Frontispiece and Plate XXV, opposite; also map, 

P- 342). 

The quarrying of the Portland Freestone was carried on only for local 

1 1926, loc. cit., p. 76. 

2 1929, loc. infra cit., p. 133. 

3 A. Strahan, 1898, loc. cit., p. 60; and see footnote above, on p. 490. 

4 1895, J.R.B., p. 192. 5 1880, loc. cit., p. 194. 

6 Rev. Coker, 1732, Survey of Dorsetshire, p. 38.

PLATE XXII 


West Weare Cliff, Portland. 

C = Cherty Series of Portland Stone, with SB = Basal Shell Bed; WWS = 

West Weare Sandstones; EB — Exogyra Bed; BNB = Black Nore Beds. 

Chesil Beach, Portland Roads and Weymouth are seen in the distance. 


Gad Cliff from Worbarrow Tout, Dorset. 

Overhanging cliff of Portland Stone and Lower Purbeck Beds. Undercliff of 

fallen blocks on Kimeridge Clay. Swyre Head in the distance.

PLATE XXII 

Photo. 

Photo. 

'Divers of those Snake or Snail Stones, as they call them, whereof great 

varieties are found in Portland, dug out of the very midst of the Quarry, of 

a prodigious bigness.' (Dr. Robert Hooke, Lectures and Discourses of 

Earthquakes, 1668 (1705), p. 327.) 

Specimens of Titanites from the Portland Stone and silicified tree-trunks from the 

Great Dirt Bed of the quarries where the stone was got for rebuilding St. Paul's 

Cathedral; photographed on Portland Island.

PORTLAND BEDS: ISLE OF PORTLAND 493 

purposes until the seventeenth century. The fame and great reputation of the 

stone dates mainly from its selection by Sir Christopher Wren for the rebuilding 

of St. Paul's Cathedral after the Fire of London, though it was 

already chosen in 1610 for rebuilding the Banqueting Hall at Whitehall. Since 

that time it has been used for well-known buildings all over the country, and 

especially in London, where its resistance to the corroding agencies in the 

atmosphere renders it particularly valuable. Among the buildings constructed 

with it are the British Museum (1753), Somerset House (1776-92), the 

General Post Office (1829), the Horseguards, the Foreign Office, and the 

Record Office; and the parts of the stone not shipped as a freestone were used 

in enormous quantities for the great breakwaters of Portland Harbour, one 

of the largest undertakings of its kind in the world, completed by convict 

labour in 1864. 

As the result of all these activities, most of the north and central parts of 

the island have been removed bodily, leaving vast expanses of rubbish tips, 

now overgrown, traversed here and there by walls and strips of unquarried 

rock. The scene has been graphically described by Sir Frederick Treves: 

4 Here is a garden of stones with roads deep in dust or deep in mud: the grass is 

grey with dust, the horses, that in teams of eight or ten drag stone-laden trolleys 

through the waste, are grey too with the powder of stone. A faded traction-engine 

rumbles by crunching the stones and blackening the air, driven by earth-coloured 

men, who are shaken as they pass by the fearful vibrations of the machine. There 

are deep pits of stone, tanks of oolite, walls of white masonry laid bare by the pick, 

terrific slopes of loose rubble sliding down into the cool sea. 

'Over a wide chasm, with sides as clean-cut as those of a graving-dock, fantastic 

cranes rise up into the air. They wave titanic arms against the sky, which might be 

the tentacles of some leviathan insect, or weave threads of wire over the abyss like 

the strands of some unearthly spider's-web; smoke rises from the gasping engines, 

while now and then a block of stone glides hissing across the void like a fearsome 

bird. All round are heaps of litter, piles of wind-blown dust, patches of scarred 

earth, and deserted pits which are becoming covered with a green mould.' 1 

Since the Great War most of the north end of the island, once the centre 

of this scene, the nucleus of one of the world's most famous quarrying localities, 

has been abandoned, and instead smaller pits are being worked farther 

south. The horse-teams, too, have gone, superseded by files of 'faded 

traction-engines', which invade the roads, sometimes ten at a time, laden with 

their huge cubes of stone. 

SUMMARY OF THE PORTLAND BEDS OF PORTLAND 2 

Titanites Zone: Freestone Series, 25 ft. 

THE ROACH, 1^-4 ft., usually about 3 ft. 

White oolitic limestone, a porous mass of hollow moulds and casts from 

which the shells have been entirely dissolved away. The commonest species 

are Aptyxiella [Cerithium]portlandica (the 'Portland Screw'), Trigonia gibbosa 

and Plicatula lamellosa Cox. The 'Screw' is entirely confined to this horizon. 

Locally in a thin layer at the top some of the fossils are silicified. 

1 Highways and Byways in Dorset, 2nd ed., 1906, p. 229. 

a The best account of the Portland Stone Series is by H. B. Woodward, 1895, J.R,B.t 

pp.198-201.


WHIT BED, 7 ft. (in places up to 15 ft.). 

Buff to white oolite, with comminuted shells, the best freestone on the 

island. In Fitton's time this was the only bed worked. Locally an irregular 

cherty band with 'sand holes' yields, according to H. B. Woodward, a micromorphic 

fauna of gastropods and marks off an additional 3 ft. to 3 ft. 9 in. 

of buff oolite below, called the Bottom Whit Bed. The Whit Bed is the 

principal source of the gigantic ammonites for which Portland is famous. 

According to Blake 'Ammonites giganteus' is confined to this horizon, but 

Woodward also records it from the Curf. Some huge specimens are preserved 

in the garden of the Portland Stone Firm's Office on the island (see PI. XXVI). 

Blake noted a plane of erosion at the base of the Whit Bed, in places cutting 

out the Curf, which is said by Woodward to be absent south of Weston. 

CURF AND CHERT, 3-6^ ft. 

Oolitic shelly limestone with numerous chert nodules. According to 

Woodward 'Ammonites giganteus is abundant'. 

LITTLE ROACH, ft. 

Oolitic limestone with hollow moulds and casts of Trigonia and other shells, 

resembling the true Roach above; not always present. 

BASE BED, 10 ft. (5-10 ft.). 

Fine-grained,buff, oolitic freestone,comparatively unfossiliferous. Some of 

the old quarries from which the Whit Bed was formerly removed are now 

being reopened to get at the Base Bed, which may be almost as good a freestone 

as the Whit Bed. 

No detailed correlation of these subdivisions with the thicker Freestone 

Series of Purbeck has yet been established. It is noteworthy that the peculiar 

white sublithographic stone, the Shrimp Bed, so constant a feature at the top 

of the formation in Purbeck, is not to be seen in Portland. Instead the top 

is formed by the equally peculiar Roach, not found in Purbeck. It is believed 

by the Worth Foreman, Mr. W. J. Bower (above, p. 485), and was suggested 

by Blake, that the Roach is equivalent to the Titanites Bed of Purbeck. This 

view is probably based on the tempting supposition that the Whit Bed freestone 

equals the Pond Freestone and that the cherty Curf is represented by 

the Chert Vein. But it must not be forgotten that the Curf and the Whit Bed 

of Portland are the home of the giant ammonites, while in Purbeck ammonites 

never seem to be found in the Chert Vein or in the Pond Freestone but occur 

in abundance in the Titanites Bed above. Until more detailed work on the 

specific identity of the ammonites in the two areas has been accomplished, the 

correlations must remain a matter of surmise. 

Kerberites Zone: Cherty Series, 60-70 ft. 

The Cherty Series is of about the same thickness in Portland as in Purbeck 

and of much the same appearance, but there is no proof that its upper limit 

is on exactly the same horizon in the two localities; the assumption is founded 

only upon the supposed equivalence of the Under Freestone to the Base Bed 

Freestone, neither of which has yielded diagnostic fossils. The Cherty Series 

is well exposed in the high crags forming the summit of West Weare Cliffs and

RIRIRITT 

TJL 

SHRIMP BED 

TITANITES BED 

POND FREESTONE 

CHERT VEIN 

HOUSE CAP 

UNDER-PICKING CAP 

UNDER FREESTONE 

CHERTY 

SERIES 

ST. ALBAN'S HEAD 

MARLS 

THE WHITE CEMENT- 

STONE 

EMMIT HILL 

MARLS 

THE MASSIVE BED 

HOUNSTOUT 

MARLS 

HOUNSTOUT 

CLAYS 

RHYNCHONELLA 

MARLS 

WXA-W- 

Q 

z 

< 

llJ M I II I I I | | I I M I I 

EXOGYRA BED 

R50FT. 

ROACH 

WHIT BED FREESTONE 

CURF SC CHERT 

LITTLE ROACH 

BASE BED FREESTONE 

CHERTY 

SERIES 

BASAL SHELL BED 

PORTLAND CLAY 

WEST WEARE 

SANDSTONES 

UPPER 

BLACK NORE 

BEDS 

BLACK NORE 

SANDSTONE 

LOWER 

BLACK NORE 

BEDS 

Fig. 84. Tables representing the Portland and subjacent rocks at Purbeck (left) 

and Portland (right). 

8O4371 

M m


Clay Hope,on thenorth-west sideof the island (PI. XXV). The hard limestones 

contain bands and nodules of chert throughout, and in places at various levels 

may be seen lenticles of cellular rock full of hollow moulds of fossils like the 

Roach. These represent Trigonia incarva and Protocardia dissimilis, not 

found in the true Roach, and also the large Behemothan ammonites distinguished 

collectively as 'Ammonites boloniensis' by the earlier writers, as in 

Purbeck. Serpula gordialis is in places so abundant that Blake called a band 

near the top a serpulite. 

BASAL SHELL BED, 7-8 ft. 

By far the most interesting feature of the series in Portland, and the richest 

palaeontological horizon in the British Portland strata, is the Basal Shell Bed. 

It forms a clearly demarcated base to the stone beds, offering a marked 

contrast to the gradual transition from cherty stone to sand in Purbeck. Until 

recently the Basal Shell Bed was comparatively little known, but in 1925 an 

extensive collection of fossils made by Col. R. H. Cunnington was described 

in a valuable monograph by Mr. L. R. Cox. 1 This has enriched our knowledge 

of the fauna of the English Portland Beds by nine new species of gastropods, 

eighteen new species of lamellibranchs, and several new ammonites, 

echinoids and polyzoa. 

The thickness of the bed is 7-8 ft. It consists largely of shells compacted 

together in a matrix of very hard limestone crowded with the tubes of Serpula 

gordialis. The whole has been almost entirely recrystallized as calcite, which 

breaks along its characteristic cleavage-planes, irrespective of the boundaries 

between shells and matrix. It is consequently impossible to separate the 

shells from the stone, except where they stand out in relief upon the weathered 

surfaces, whence they can be removed with a hammer and chisel. The fauna 

consists principally of lamellibranchs, of which Mr. Cox records over 50 

species. The commonest forms are those most frequently met with in the 

middle and lower parts of the Cherty Series in Purbeck, such as Isognomon 

bouchardi, Chlamys lamellosa, &c. The ammonites, although scarce, sufficed 

for Buckman to pronounce them as fairly evidently of late Behemothan date; 

they include the usual large forms of'bononiensis' style, the type-specimen and 

other material of Kerberites portlandensis Cox, and forms resembling Glaucolithites 

gorei (Salf.). 

Glaucolithites Zone: Portland Sand, about 100 ft. 

The Portland Sand of Portland still remains palaeontologically almost unknown. 

Its general lithic character is much like that of Eastern Purbeck, but 

the details are entirely different. 

At the north end of the island, under the Verne Fort, the highest member 

is a 10 ft.—14 ft. band of stiff blue marl, called by Damon the PORTLAND 

CLAY. 2 This is not present in the other sections; in the clearest of all, at West 

Weare Cliff, the Basal Shell Bed of the Portland Stone is immediately underlain 

by 30 ft. of brown and grey marly sandstones and sandy cementstones of 

varying degrees of hardness. From these Salfeld recorded Glaucolithites 

gorei, 3 and other records by Blake show the desirability of further collecting. 

1 L. R. Cox, 1925, Proc. Dorset N.F.C., vol. xlvi, pp. 113-72. 

2 R. Damon, i860, Geol. Weymouth, p. 82. 

3 H. Salfeld, 1914, Neues Jahrb. fur Min., B.-B. xxxvii, p. 191.

PORTLAND BEDS: ISLE OF PORTLAND 497 

Towards the north end of the island, according to the measurements of Mr. 

Lattef, these sandstones thicken considerably. It is convenient to distinguish 

them by the name WEST WEARE SANDSTONES. 

Beneath is the most conspicuous band in the series, the EXOGYRA BED. It 

consists of 6-8 ft. of stiff marl packed with almost a solid mass of Exogyra nana 

(Sow.), 1 and it weathers to a prominent massive band easily recognized in the 

cliff (Frontispiece and PI. XXV). According to Latter the top of the Exogyra 

Bed is 31 ft. below the Shell Bed in West Weare Cliff and 57 ft. below it at 

the north end of the island. 

The lower beds are imperfectly exposed, but a considerable thickness of 

sandy beds is present at West Weare Cliff, below Black Nore Gorge, and they 

may be appropriately referred to as the BLACK NORE BEDS. The Upper Black 

Nore Beds consist of black sands with lines of light grey nodules, 35 ft. thick 

according to Latter. 2 They are separated from the Lower Black Nore Beds 

by a 6 ft. band of hard, black, argillaceous sandstone with large intensely hard 

concretions. 3 The Lower Black Nore Beds 4 consist of blue-black sandy clays, 

extending as far as the foot of the visible section, 40 ft. below the Black Nore 

Sandstone. 

The Portland Sand of Portland may therefore be summarized as follows: 

TABLE OF THE PORTLAND SAND OF PORTLAND 

Portland Clay (north end of island only) . . . 

ft. 

14 

West Weare Sandstones . . . 30 ft. to about 40 

Exogyra Bed . . . . . . . . 8 

Upper Black Nore Beds . . . . . - 3 5 

Black Nore Sandstone . . . . . . . 6 

Lower Black Nore Beds . . . . . seen to 40 

Total about 140 

In the present state of palaeontological knowledge it would be rash to 

attempt any correlations with Purbeck. If we assume that the upper limit is 

drawn on the same horizon as in Purbeck (itself an unsafe assumption) then 

there is a close agreement in aggregate thickness if we take the base at the 

bottom of the Black Nore Sandstone, and moreover the Black Nore Sandstone 

falls into line with the Massive Bed of Purbeck. The presence in the Massive 

Bed in one locality at Chapman's Pool of a considerable quantity of Exogyra 

nana suggests correlation rather with the Exogyra Bed; but Rhynchonella 

portlandica, which is associated with it, has not been found in the Exogyra 

Bed, and the futility of placing any reliance on the oyster is demonstrated by 

the much later oyster-bed near the top of the Freestone Series at Tilly Whim 

(above, p. 486). Aggregate thicknesses are here likely to be a safer guide for 

a working hypothesis, and it seems likely that the sandy clays constituting 

the Lower Black Nore Beds will one day prove to be the Hounstout Marl, 

regarded here as belonging to the Kimeridge Clay (above, p. 446). 

1 Usually known by the synonym, E. bruntrutana Thurm., see Jourdy, 1924, 'Hist. nat. 

des Exogyres', Ann. Pal., vol. xiii. 

2 Latter's Bed 3 at Black Nore Gorge, 1926, loc. cit., p. 82. Latter calls all the nodules and 

concretions, both here and in Purbeck, septaria, but very few are septarian. 

3 Latter's Bed 2, loc. cit., p. 82. 

4 Latter's Bed 1.

498 

UPPER OOLITES 

(c) The Northern Limb of the Weymouth Anticline 

The Portland Beds in the northern limb of the Weymouth Anticline are 

distant from Portland Island only 5 miles across the bay, but they differ 

profoundly from their equivalents on the island. They also differ as much 

from the Portland Beds of Purbeck, and the change from the Purbeck and 

Portland type of development can be traced north-westwards through the 

numerous small connecting outcrops along the sea-coast, at Lulworth, Durdle 

Door and the Cow and Calf Rocks. Beyond the last outlying rock there is 

a gap of 2 miles to the faulted mass below Holworth House, Ringstead Bay, 

whence the outcrop is continuous, except for minor interruptions, to Portisham. 

The Portland Beds, capped by Purbecks, form a lower escarpment and 

spurs jutting out below the main cuesta of the Chalk Downs. Where they 

enter into the Chaldon Anticline they surround and floor an elongate inlier, 

giving rise to a striking amphitheatre known as Poxwell Circus. 

It was remarked that even so far east as Gad Cliff great changes were to be 

seen in both the Portland Stone and the Portland Sand. There Hudleston 

noted that the Shrimp Bed and Titanites Bed seem to rest directly on the 

Cherty Series, while the Portland Sands are both sandier and thinner, and 

the divisions established farther east cannot be recognized. In the main outcrop 

from Ringstead Bay westward the differences are intensified, the whole 

formation dwindling to less than 80 ft. at Portisham. 

The Titanites Zone or Freestone Series presents a curious blend of the 

various beds developed in Portland and Purbeck. A close study of their local 

changes might provide a key to the correlation of the two better-known areas, 

but no such investigation has yet been undertaken. In Ringstead Bay the 

series is represented by variable, oolitic, shelly and chalky limestones, 12 to 

18 ft. thick, containing Roach as at Portland, in the upper and lower parts. 

Roach is also present at Sutton Poyntz, in the neighbourhood of which 

'Ammonites giganteus' is described as abundant. At Greenhill Barton there 

is an oyster-bed like that at Tilly Whim. 1 

The greatest attenuation seems to take place in the middle of the outcrop, 

at Upway, where only 3 ft. of Roach intervenes between the Purbeck Caps 

and the Cherty Series. The thickness at Portisham is 5 ft., but the roach has 

there given place to a hard limestone. We are warned by the presence of the 

Chert Vein in the centre of the Freestone Series of Purbeck against assuming 

that the chert nodules terminate everywhere on one and the same horizon. 

The Kerberites Zone or Cherty Series, however, is hardly likely to embrace 

representatives of much of the overlying strata, for it is itself greatly reduced 

in thickness, measuring only 30 ft. at Portisham. Its most noticeable feature 

is an extreme whiteness of the limestone, which renders the series hard to 

distinguish from Chalk-with-flints. The Basal Shell Bed is represented at 

Portisham, where the lowest 6 ft. of the series consists of limestone crowded 

w T ith Serpula gordialis and shells. Farther east, however, the bed does not 

seem to have been recognized, and there is nothing that could be said to 

represent it in the cliff-section below Holworth House in Ringstead Bay. 

The Portland Sand has recently been the object of petrological investigation 

by Mr. M. P. Latter, who emphasized the much higher proportion of 

1 A. Strahan, 1898, loc. cit., p. 69.

PORTLAND BEDS: NORTH OF WEYMOUTH 499 

true sand here as compared with Purbeck or Portland. Commensurate with 

the increase of sand, an increase in the quantities of heavy minerals was 

noticed, especially garnet, tourmaline, zircon and rutile, accompanied by 

kyanite, staurolite, muscovite and glauconite. 1 These facts he rightly considered 

to indicate that the shore-line lay to the north-west. Concerning the 

origin of the heavy minerals, however, his results are diametrically opposed 

to those of Dr. A. W. Groves. While Mr. Latter concluded that the heavy 

minerals 'point to the granite massifs of Devon and Cornwall as being the 

main source of origin for the Portland Sand', Dr. Groves asserts 'No indication 

whatever has been found of direct derivation of detritus from Dartmoor 

in the Jurassic rocks of Dorset, nor inland as far as the Oxford district ... in 

the Portland Sand detritus resembling Dartmoor material is referred with 

more certainty to the granites of Normandy and Brittany.' 2 

The best section of the Portland Sand is to be seen in the faulted block 

below Holworth House, in Ringstead Bay. It has been described by Woodward, 

Strahan, Latter and Buckman, but the descriptions vary so greatly that 

it is almost impossible to discern a single feature in common. Woodward's 

total thickness adds up to 69 ft., Strahan's to 57 ft., Latter's to 121 ft., and 

Buckman's to 48 ft. 2 in.! Buckman, however, stated that his thicknesses were 

'only guess-work', 3 while Latter evidently included in the Portland Sand most, 

if not the whole, of the Cherty Series. The downward passage from Cherty 

Series to Sands is, in fact, quite gradual, as at St. Alban's Head, but here there 

are no Parallel Bands to guide us in our arbitrary selection of a junction. 

Buckman found,, somewhere near the base of the section, a 2-in. seam of 

marly clay containing Rhynchonella portlandica Blake, Lingula ovalis auctt., 

and two minute species of Orbiculoidea no bigger than a large pin's head. On 

account of the Rhynchonella he was inclined to correlate this seam with the 

Massive Bed of Purbeck. 4 

Woodward noted, about 20 ft. from the top selected by him, 10 ft. of calcareous 

sandstone with Exogyra, Ostrea and Trigonia, which suggests a possible 

correlation with the Exogyra Bed of Portland; he also recorded Exogyra 

in about the same position at Portisham. 5 

The presence of glauconite grains in the Portland Sands of this district is 

of great interest in view of the important part that they play in rocks placed 

on palaeontological grounds on the same horizon farther inland. The chalky 

condition of the Cherty Series is also of considerable assistance in correlating 

with the next district to the north—the Vale of Wardour. 

II. THE WESTERN RIM OF THE WILTSHIRE DOWNS 

Owing to the unconformable overstep of the Cretaceous rocks, the Portland 

Beds are almost entirely concealed inland. Only two glimpses of the main 

outcrop are obtained under the western rim of the Wiltshire Downs, where 

deep notches have been cut back into the Chalk to form the Vales of Wardour 

and of Pewsey; and farther north two small outliers have been preserved in 

synclines on the Kimeridge Clay at Swindon and Bourton. The fact that the 

1 M. P. Latter, 1926, loc. cit., pp. 89-90. 

2 A. W. Groves, 1930, Q.J.G.S., vol. lxxxvii, pp. 86, 70. 

3 T.A., vol. vi, p. 37. « Ibid. 

s H. B. Woodward, 1895, J.R.B., p. 194.

FIG. 85. Sketch-map of the Vale of Wardour, to show the outcrop of the Portland and Purbeck Beds. The thick black line 

represents the unconformity at the base of the Upper Cretaceous (Albian). (Based on W. II. Hudleston, 1881, Proc. Geol. 

Assoc., vol. vii, p. 163; re-drawn.)

PORTLAND BEDS: VALE OF WARDOUR 501 

only two recessions in the Downs disclose Portland Beds in normal superposition 

above the Kimeridge Clay, while the larger, the Vale of Wardour, 

shows Purbeck Beds and Wealden Sands also, suggests strongly that the outcrop 

of these beds is continuous beneath the Cretaceous covering. The covering 

is so thick that it has never been penetrated by wells. 

In a series so variable, the discontinuity of the visible outcrops renders 

detailed correlation from place to place exceedingly difficult. The total area 

of Portland rocks exposed at the surface in Wiltshire does not exceed 4 miles 

square. On the other hand, the distance of the Vale of Wardour from the 

nearest outcrop to the south, the Isle of Purbeck, is 30 miles; while another 

14 miles intervenes between the Isle of Wardour and the Vale of Pewsey, 

which is separated by a further 18 miles from the outlier at Swindon. From 

such fragmentary evidence we cannot hope to piece together more than a very 

incomplete picture of the inland Portland Beds. 

(a) The Vale of Wardour 

By far the largest and most important surface-outcrop is that of the Vale of 

Wardour, lying in the extreme south-west corner of Wiltshire, 10 miles west 

of Salisbury. The remarkable geological features of the Vale have been 

described by many writers. The River Nadder gathers the surface water 

from the Kimeridge Clay north of Shaftesbury and carries it eastward across 

the strike of both the Jurassic and the Cretaceous formations into the heart of 

the Chalk Downs, to join the Avon at Salisbury. In the apex of the narrowing 

valley, before the river passes on to the Chalk, the Portland, Purbeck and 

Wealden Beds are laid bare in a trough 8 miles long and 2 miles wide at the 

widest end. They strike N.-S. across the floor of the valley and disappear 

on both sides beneath the walls of Gault, Upper Greensand and Chalk (map, 

opposite). 

The main outcrop of the Portland Beds occupies a dissected upland plateau 

within the Vale, surrounding the town of Tisbury. A number of quarries 

have been exploited for building-stone in the past, and one or two are still 

working. The principal exposures, however, lie about a mile to the east of 

the main outcrop, in the sides of a valley known as the Chilmark Ravine, 

where a roll brings the Portland Beds to the surface through the Purbeck Beds 

in an outcrop about a mile long and a few hundred yards wide. This picturesque 

ravine, thickly wooded, and scarred beneath the vegetation by 

numberless ancient quarries and tip-heaps, has for hundreds of years yielded 

the Chilmark Stone, which was well known long before the Portland Stone 

was heard of. It was employed in many important buildings in the South of 

England, among them the cathedrals of Salisbury, Chichester and Rochester, 

the Chapter Houses of Westminster Abbey, Christchurch Priory, Wardour 

Castle, Lulworth Castle, and Fonthill Abbey. 

The Chilmark Stone is at present worked only in one locality, by means 

of an underground gallery in the west side of the ravine. In the past it was 

obtained in large open quarries as well as underground galleries, and some 

still afford good exposures, especially the largest quarry at the north-west end 

of the ravine. 

The main building-stones are about 18 ft. in thickness and consist of 

peculiar glauconitic and sandy limestones, very different in appearance from


the Portland and Purbeck-Portland freestones. Moreover, they form the base 

of the local Portland Stone, while above them follow thick chalky limestones 

with veins and nodules of chert, identical with the Cherty Series of the Upway- 

Portisham district; and these are in turn succeeded by an upper series of 

freestones more like those of Dorset. 

There seems little doubt on stratigraphical grounds that the main buildingstones 

of the Vale of Wardour correspond with the upper part of the Portland 

Sands of Dorset, which become glauconitic in the northern limb of 

the Weymouth Anticline (p. 499). They are probably to be correlated with 

the West Weare Sandstones of Portland, and so with the upper part of the 

Glaucolithites or 'goreV zone. Beneath are some 38 ft. of sandy strata corresponding 

with the rest of the zone. So far as I am aware this correlation has 

not been put forward previously, and the study of the ammonites is not yet 

sufficiently advanced to establish it on a palaeontological basis. But since it 

seems to be the only one by which the Portland Beds of the Vale of Wardour 

can be brought into line with those in Dorset, it is tentatively adopted here. 

The succession has been very thoroughly elucidated by Hudleston, Blake, 

and H. B. Woodward. They built on foundations laid by Fitton, W. R. 

Andrews of Teffont Evias, and Miss Etheldred Benett, one of the earliest of 

lady geologists, who in the early part of the nineteenth century resided at the 

stately Pyt House, west of Tisbury. In the following summary the succession 

established by these geologists is fitted into the classification used throughout 

this chapter. 

SUMMARY OF THE PORTLAND BEDS OF THE VALE OF WARDOUR 1 

Titanites Zone: Upper Building Stones, 0-16 ft. 

The Upper Building Stones consist of fine-grained, white or buff, siliceous, 

oolitic limestones, locally passing into Roach, full of cavities whence the 

fossils have been dissolved out. The better quality stone takes fine carving 

and, being very durable, was used in the elaborately carved west front of 

Salisbury Cathedral. The principal fossils are Aptyxiella portlandica (confined 

to this horizon as at Portland), Trigonia gibbosa, Neomiodon cuneatum 

(Sow.) [= Cyrena or Cytherea rugosa auctt.], Eodonax dukei (Mor. and Lyc.), 

Protocardia dissimilis, Chlamys lamellosa, Neritoma sinuosa, Ampullina ceres, 

and Lucina portlandica. There are occasional chert veins in the lower part of 

the series. 

Locally in the south of the area, as at Chicksgrove Mill Quarry, the Upper 

Building Stones are absent, owing either to attenuation or to the unconformable 

overlap of the Purbeck Beds, thus recalling the wedging out of the Freestone 

Series in Gad Cliff. 

Kerberites Zone: Cherty Series and Ragstone Beds, 30-5 ft. 

CHALKY OR CHERTY SERIES, 24 ft. 

The Cherty Series is identical with that in the northern limb of the Weymouth 

Anticline, consisting of soft, white, chalky limestone, burnt for lime, 

1 Based on J. F. Blake, 1880, loc. cit., pp. 199-203; W. H. Hudleston, 1883, 'The Geology 

of the Vale of Wardour', P.G.A., vol. vii, pp. 161-85; H. B. Woodward, 1895, J.R.B., 

pp. 203-9.

PORTLAND BEDS: VALE OF WARDOUR 503 

with many veins and nodules of black flinty chert. The fossils are mainly of 

large size and include many big ammonites recorded as 'A. boloniensis\ like 

those abounding on the slabs at Dancing Ledge and Winspit, but as yet 

unstudied (Buckman figured one specimen from Chilmark as 6 Galbanites* 

cretarius). 1 The other fossils are principally Chlamys lamellosa, Ostrea expansa, 

Protocardia dissimilis and Trigonia gibbosa; the last forms locally a bed 

of Roach at the base, comparable with the roach-beds in the Cherty Series 

of Portland. According to Hudleston the upper part of the series is missing 

at Chicksgrove Mill. A local chert vein near Tisbury formerly yielded 

silicified specimens of the coral, Isastrcea oblonga, which were cut and 

polished and were famed as long ago as 1729 under the name of 'Starr'd 

Agates 5 . 2 

THE RAGSTONE BEDS, 8-10 ft. [= BASAL SHELL BED?]. 

At the base of the Cherty Series are 8-10 ft. of strongly-bedded, very shelly 

limestone, containing quartz grains but no glauconite, and divided by marly 

partings. In the state of preservation of their fossils as well as in their 

stratigraphical position these Ragstones resemble the Basal Shell Bed of the 

Isle of Portland. Before the wonderful fauna of the Portland stratum was 

made known by Mr. Cox, Hudleston declared that no Portland rock in England 

contained such w r ell-preserved fossils as the Ragstones of Chilmark. The 

fauna, however, has received relatively little study, and no ammonites are 

known. The most abundant species is Neomiodon cuneatum (Sow.), a small 

lamellibranch that has given rise to more discussion and misconceptions than 

any other in the Upper Jurassic. 3 It is in appearance like a strongly-ribbed 

Astarte, but the hinge bears the dentition of Neomiodon, to which belongs the 

freshwater Cyprinid shells common in the Purbeck Beds and formerly known 

as Cyrena. On this account Hudleston called the Ragstones the Cyrena Beds 

and the Upper Building Stones the Upper Cyrena Beds, even going so far as 

to say that they had an estuarine or fluvio-marine origin. But of this Neomiodon 

cuneatum is no evidence, for although it has not been found in the 

Basal Shell Bed (or any other part of the Portland Series) of Portland, it 

ranges on the Continent throughout the Kimeridgian and Portlandian stages, 

where it certainly lived under purely marine conditions. It differs from the 

Purbeck species in being strongly ribbed like an Astarte, whereas they are 

smooth, and its generic affinities are still somewhat doubtful. 

Other common fossils in the Ragstones are 4 Cerithiumconcavum Sow., 

a number of other gastropods, and such familiar marine forms as Protocardia 

dissimilis and Lucina portlandica. 

Glaucolithites Zone: Portland Sand, 50-60 ft. 

MAIN BUILDING STONES, 18 ft. 

The main building stones of Chilmark and Tisbury consist of glauconitic 

and sandy limestones varying from green to brownish-buff in colour. They 

are of generally uniform appearance, but the quarrymen detect slight differences 

and give to each bed a distinguishing name. The names vary in different 

1 T.A.y 1925, pi. DCXXI. 


3 L. R. Cox, 1929, Proc. Dorset N.F.C., vol. 1, pp. 175-6.


parts of the district and they are now for the most part dying out; Woodward 

listed the following: 

Trough Bed with T. gibbosa 

Green Bed . 

Slant Bed . 

Pinney Bed . 

Cleaving or Hard Bed . 

Fretting Bed. 

Under Beds . 

ft. in. 

2 8 

5 o 

1 o 

2 0 

I 0 

3 4 

3 o 

18 ft. o in. 

Fossils are generally scarce, but Trigonia gibbosa is not uncommon in the 

Trough Bed, and the Pinney Bed receives its name from an abundance of 

Serpulce. Some ammonites occur, recorded by Blake as'A. boloniensis' and'A. 

biplex\ The latter is suggestive of Glaucolithites, but the forms have not been 

worked out according to modern standards. One, however, has been figured 

by Buckman from the Green Bed as Gyromegalites polygyralis 

BASEMENT BEDS WITH UPPER LYDITE BED, 30-40 ft. 

Woodward records that a well was sunk at the base of the Chilmark 

(Teffont) Quarry beneath the Building Stones to a depth of 38 ft., through 

clays and calcareous sandy bands to black Kimeridge Clay. These sandy 

strata, called the Basement Beds by Hudleston, seem to have been seen only 

twice in temporary excavations. In the railway-cutting (now overgrown) 

w r est of Chicksgrove Mill, east of Tisbury, Woodward described 15-20 ft. of 

'brown and greenish-brown sand with clay seams and bands of indurated 

sand, containing casts of shells here and there and thin beds of stone near the 

top'. These beds seemed to merge up gradually into sandy, shelly and 

glauconitic limestone, presumably representing the base of the Building 

Stones. 2 

A more interesting section was described by Blake and by Hudleston, 

exposed in a road-cutting near Hazelton, between Tisbury and Wardour. 3 

Beneath the Building Stones were 7 ft. of loose sands with doggers, underlain 

by 3 ft. of greenish concretionary gritstone, and below all, sands and clays 

seen to 21 ft. The chief centre of interest was the 3 ft. of gritstone, which 

contained not only badly-preserved Trigonia, Isognomon bouchardi, Chlamys 

lamellosa, Protocardia dissimilis, Exogyra nana, &c., but also occasional lydite 

pebbles. 

This is the most southerly known occurrence of lydite pebbles. They 

become a constant feature in the more northerly areas, at Swindon and in 

Oxfordshire and Buckinghamshire, where they occur always on the same 

horizon and form the Upper Lydite Bed. 

(b) The Vale of Pewsey 

A small area of Portland Beds peeps out from beneath the Cretaceous rocks 

at the mouth of the Vale of Pewsey, between Potterne and Coulston, near 

Devizes, but exposures are too meagre for the succession to be made out. 

Woodward described diminutive exposures of several types of rock: cherty 

1 T.A.y pi. DCXX, c, d. 2 H. B. Woodward, 1895, pp. 206, 204. 

3 W. H. Hudleston, 1883, P.G.A., vol. vii, p. 172.

PORTLAND BEDS: SWINDON 505 

beds, fossiliferous gritty limestone, gritty and glauconitic limestone with an 

occasional lydite pebble, and glauconitic sands with concretions. 1 Not for 

another 18 miles, until Swindon is reached, 32 miles from the Vale of Wardour, 

do the Portland Beds again come to the surface. 

(c) The Swindon Outlier 

The hill upon which Old Swindon is built is capped with Portland and 

Purbeck Beds. They probably owe their preservation to being situated in 

a synclinal depression on the outskirts of the area where the Cretaceous rocks 

normally would overstep on to Kimeridge Clay, for they seem to be an outlier: 

no trace of them was found in a boring carried through the Cretaceous rocks 

at Bur drop, between Wroughton and Chiseldon, on the south. 

Thanks to two extensive quarries on the summit of the hill, described in 

detail by Blake, and to a railway-cutting opened subsequently to Blake's work 

and described by H. B. Woodward (fig. 79, p. 456), the succession is known 

in considerable detail. The zonal positions of the subdivisions were established 

by the palaeontological work of Dr. Salfeld, whose results were later 

corrected and amplified by Messrs. Pringle and Chatwin. 

The highest part of the Portland Stone (the Titanites zone) and the Purbeck 

Beds are seen only in the Town Gardens Quarry, long ago abandoned and 

now rapidly deteriorating. The lower zones and the junction with the 

Kimeridge Clay, which were also exposed in the railway-cutting near Old 

Town Railway Station, are well displayed in Okus Quarry, on the western 

end of the hill. Here work is still carried on apace and many gigantic ammonites 

may be obtained. Although some of them reach almost the dimensions 

of the giants of Portland and Purbeck, they are of different genera, 

characteristic of the earlier Behemothan Age, and they are associated with 

species of Kerberites. 

There are several new features not met with farther south, but perhaps the 

most important is the extremely thin representation of the Portland Sand, 

which is reduced, both here and in the more north-easterly areas, to a few feet 

of Glauconitic Beds with the Upper Lydite Bed at the base. 

SUMMARY OF THE PORTLAND BEDS OF SWINDON 2 (fig. 86) 

Titanites Zone: The Creamy Limestones, about 10 ft. 

As elsewhere, the beds of the Titanites zone are highly variable in short 

distances, a fact which has given rise to considerable discrepancies in the 

accounts of the succession seen in the old Town Gardens Quarry. In places 

the whole zone is absent and the beds beneath are overlain directly by Purbeck 

Beds. 

Where they are preserved, there is at the top up to 6 ft. of pale, creamcoloured 

marly limestone, suggestive of some of the Purbeck Beds, but containing, 

rarely, shells of Trigonia. Beneath comes 4 or 5 ft.of Roach like that at 

Portland, riddled with hollow moulds of Aptyxiellaportlandica, here associated 

with an equal abundance of Neomiodon cuneatum, and the usual Trigonia 

1 H. B. Woodward, 1895,^.^., p. 210. 

2 J. F. Blake 1880, loc. cit., pp. 203-13; H. B. Woodward, 1895, J.R.B., pp. 210-15; 

Chatwin and Pringle, 1922, Sum. Prog. Geol. Surv. for 1921, pp. 162-8 (see also 1922, P.G.A., 

vol. xxxiii, pp. 152-5).

5O6 UPPER OOLITES 

gibbosa, Chlamys lamellosa and Protocardia dissimilis. Apparently no ammonites 

have been found in these beds. 

According to Blake there is at the base a distinct discordance. 

Kerberites Zone: Swindon Sand and Gockly Bed, 30 ft. 

THE SWINDON SAND AND STONE. 

This is the thickest part of the Portland Beds of Swindon, consisting of 

SWIN DON 

PURBECK BEDS 

LONG CRENDON AYLESBURY 

FIG. 86. Comparative sections showing the Portland Beds of Swindon, Long Crendon (after 

Buckman) and Aylesbury (after Woodward and Hudleston). 

25 ft. of buff and white false-bedded sands with bands and lenticles of 

calcareous sandstone. Locally the sands are largely made up of comminuted 

oysters and Pectens, and they also contain some lignite; but on the whole they 

are very poorly fossiliferous, and ammonites seem to be unknown. The 

Swindon Sand forms the lower part of the section in the Town Gardens 

Quarry and the upper part of that in Okus Quarry, and it is still well exposed 

in the railway-cutting (fig. 79). Blake correlated the beds with the Cherty 

Series of Portland, a view which still seems probably correct.

THE COCKLY BED. 

PORTLAND BEDS: SWINDON 507 

At the base of the Swindon Sand in Okus Quarry is a 4 ft. bed of creamy 

limestone crowded with fossils, for the most part in the form of moulds and 

casts, named the Cockly Bed to distinguish it from the Roach of higher 

horizons. The Cockly Bed is the source of nearly all the ammonites found in 

the Portland Stone of Swindon, and some are of gigantic size, but they still 

remain to be adequately described and figured. Salfeld and subsequent 

writers identified the commonest form as 'Perisphinctes' pseudogigas Blake, 

but more recently Buckman has chosen a neotype of Blake's species from the 

Titanites zone of Buckinghamshire. A number of the Swindon forms will 

probably fall into the genus Behemoth of Buckman. The other common type 

of ammonite is the genus with heavy triplicate ribbing now known as Kerberites, 

of which the Cockly Bed of Okus Quarry is the source of the types of 

K. trikranus Buck. 1 and K. okusensis (Salfeld). 2 K. kerberus Buck, is also 

common; the holotype came from Chicksgrove near Tisbury, but from 

exactly which horizon is uncertain. 3 

Other common fossils of the Cockly Bed, approximately in order of abundance, 

are Protocardia dissimilis, Trigonia incurva, T. gibbosa, Isognomon 

bouchardi, Pleurotomaria rugata, Pleuromya tellina, Mytilus suprajurensis Cox. 

The bed is simulated in appearance by the lenticles of Roach in the Cherty 

Series of Portland. 

Glaucolithites Zone: Glauconitic Beds and Upper Lydite Bed, 3! ft. 

The Portland Sand is very greatly reduced, consisting of only 3-J- ft. of 

glauconitic, sandy limestone, with at the base a well-marked layer of lydite 

and phosphatic pebbles—the Upper Lydite Bed, so called to distinguish 

it from the Lower Lydite Bed at the base of the Swindon Clay (see 

P- 457)- 

The glauconitic limestone contains Glaucolithites gorei (Salf.) which is 

found in the upper part of the Portland Sand of Dorset (the West Weare 

Sandstone), and a number of similar forms, some of which have been figured 

and named by Buckman; e.g. Polymegalites polypreon 4 and Gyromegalites 

polygyralis. 5 The last was also figured from the Green Bed of the Main 

Building Stones of Chilmark. 6 The Upper Lydite Bed, aptly styled many 

years ago by Hudleston 'the basal conglomerate of the Portlands', contains 

rolled and phosphatized fragments of small ammonites derived from the 

Pavlovia zones of the Kimeridge Clay,upon which it reposes non-sequentially. 

If we correlate it with the Lydite Bed in the Vale of Wardour (as seems 

reasonable) it is evident that the bulk of the Portland Sands of that locality 

are missing at Swindon. Assuming that the portion of the Portland Sands 

above the Lydite Bed in the Vale of Wardour (the Main Building Stones 

and 7 ft. of sands) is approximately equivalent to the West Weare Sandstone 

of Portland and the St. Alban's Head Marl of Purbeck, then it 

emerges also that some 130 ft. of Dorset strata are wanting in this position 

at Swindon. The scythicus zone has nowhere been detected inland. 

1 T.A.y 1924, pi. DXXXV. 

3 T.A., 1924, pi. DXX and 1926, pi. DXX, a-b. 

5 T.A.y 1925, pi. DCXX, a and b. 

2 T.A.y 1925, pi. DLXX. 

4 T.A.y 1925, pi. DXCI. 

6 T.A.y 1927, pl.Dexx, candd.

552 

UPPER OOLITES 

(d) The Bourton Outlier 

Five miles east of Swindon, just over the Berkshire border, a tiny outlier 

of Portland Beds, only half a mile in diameter, forms the hill on which the 

village of Bourton stands. The stone was formerly quarried in a large pit on 

the south of the village, at Bourton End, but the sides are now sloped and 

overgrown, and the excavation is full of water. The complete succession on the 

hill was made out by Godwin-Austen in 1850, 1 and the quarry was again 

described by Sir Andrew Ramsay in 1858. 2 The succession is essentially the 

same as at Swindon, except that there are a few feet (7 ft.?) of sands below 

the Lydite Bed. It is possible that this represents some portion of the Portland 

Sand, preserved here below the Lydite Bed, but it is more probable that it is 

a sandy development of the upper part of the Swindon Clay, equivalent to the 

Thame Sand of Oxfordshire (see above, p. 458). A recent excavation already 

referred to (p. 458), lower down the hill south-east of the old quarry, has 

proved that the lower part of the Swindon Clay is present in normal development, 

with the Lower Lydite Bed at the base, resting on the Shotover Grit 

Sands or pectinatus zone. 

Combining Godwin-Austen's and Ramsay's description with this new 

information, it is possible to piece together the full succession at Bourton, as 

follows: 

3 

O 

SUCCESSION AT BOURTON 

Interpretation. Record (Godwin-Austen). Ft. 

CREAMY LIMESTONE 

SWINDON SAND 

COCKLY BED 

GLAUCONITIC BEDS 

AND 

UPPER LYDITE BED 

' ? THAME SAND 

SWINDON CLAY 

LOWER LYDITE BED 

„ SHOTOVER GRIT SANDS 

Stratified earthy oolite: Ammonites and casts 

of Trigonia . . . . . 8 ? 

Buff and yellow sand; no fossils . . .12 

Flat-bedded white oolitic sand . . . 8 

Rubbly oolite: large Pleurotomarice . . 1 

Ostrea and Perna bed . . . . . ? 

Pebbles in calcareous beds: fossils numerous 10 

(Ramsay calls the base of this 'a bed of hard 

bluish fossiliferous limestone with pebbles 

of Lydian stone and white quartz') 

Fine sands . . . . 7 ? 

Kimeridge Clay below. 

(Swindon Clay, base greenish, sandy) geen 

(Lower Lydite Bed, lydites abundant, \ ft.) I in 

(Sands with large doggers, seen to 4 ft.) J 

III. THE OXFORDSHIRE AND BUCKINGHAMSHIRE AREA 

The most northerly area of Portland Beds exposed at the surface in Britain, 

and also the largest, extends from Nuneham Courtenay, on the east bank of 

the Thames, in a north-easterly direction for 25 miles past Thame and 

Aylesbury to Whitchurch and Stewkley, on the watershed of the Ouse. It is 

now dissected by the River Thame and its tributaries into scattered groups of 

outliers, but the original area covered by the Portland Beds now exposed must 

1 R. A. C. Godwin-Austen, 1850, Q.J.G.S., vol. vi, p. 462. 

2 A. Ramsay, 1858, 'Geol. Parts of Wilts. & Gloster', p. 27, Mem. Geol. Surv.

PORTLAND BEDS: OXFORD AND AYLESBURY AREA 509 

have been at least 25 miles long and more than 8 miles wide. The southwestern 

edge of the area is 21 miles from Bourton. 

The principal outlier, usually designated the main outcrop, lies between 

Thame and Aylesbury, and, with the many others to the north and west, forms 

a pleasant country of small hills, often capped by Purbeck Beds, Lower 

Greensand or Gault, and separated by valleys of Kimeridge Clay. 

The Cretaceous rocks overstep from the south and south-east in such a way 

that the Portland Beds seem to have been isolated like those at Swindon. In 

consequence also of this overstep, especially on the southern and southeastern 

margins of the area, the sequence is often incomplete. The effect is 

most marked in Oxfordshire, about Haseley, the Baldons, the Miltons, and the 

long ridge of Shotover Hill, running from Garsington and Cuddesdon to 

Headington, where the Titanites zone is often absent. In the parallel ridge 

running from Thame to Long Crendon and Chilton and terminating in the 

outliers of Brill and Muswell Hills, and also in the central area about Haddenham, 

Cuddington and Hartwell, higher beds are present. From here many 

giant ammonites of the Titanites zone, like those at Portland, have been 

obtained. Down the dip-slope, about Thame, on the contrary, the Portland 

Stone Series seems to have been in places entirely removed by the Cretaceous 

denudation. 

In the most northerly outliers, about Quainton, Oving, Whitchurch and 

Stewkley, exposures are now meagre, but the succession was accurately 

described by Fitton, and it is evident that it is complete. North-east of Aylesbury, 

the Gault cuts out the Portland Beds entirely, coming to rest on the 

Kimeridge Clay and finally on the Oxford Clay. 

Although this area is so large in comparison with the Wiltshire outcrops, 

it will suffice for our present purpose to summarize its features as a whole, in 

a single generalized succession. The same subdivisions as at Swindon may 

be recognized; in particular there is almost the same reduction of the Portland 

Sands to a few feet of Glauconitic Beds, with the Upper Lydite Bed at the base. 

The sequence has been elucidated by a number of distinguished geologists. 

The groundwork was as usual laid by Fitton, 1 who described in detail many 

sections long since abandoned and too often completely obliterated. His 

careful work, which has preserved for our benefit many valuable and irretrievable 

records, provides an outstanding example of the importance of recording 

every exposure before economic vicissitudes render it too late and the information 

is lost. Blake in 1880 summarized the succession, 2 introducing the 

four main subdivisions used at the present day. At the top he divided off beds 

of 'compacted shell brash 5 and 'creamy limestones 5 (now grouped together 

as the Creamy Limestones), separated by sands (the Crendon Sands of 

Buckman forty-five years later) from a lower set of highly fossiliferous 

'Rubbly Limestones 5 . Below these he recognized the Glauconitic Beds and 

the Lydite Bed at the base. Blake's correlation of these subdivisions with 

those at Swindon, however, was somewhat wild. 

Between 1880 and 1890 Hudleston led several excursions of the Geologists 5 

Association over the ground in the neighbourhood of Aylesbury, publishing 

detailed accounts of the succession at the Bugle Pit, Hartwell, and at Aylesbury 

1 W. H. Fitton, 1836, Trans. Geol. Soc. [2], vol. iv, pp. 269-95. 

2 J. F. Blake, 1880, loc. cit., pp. 213-21.


and Bierton. 1 The whole area was revised by H. B. Woodward in 1895 and 

Blake's correlation was criticized. In particular Woodward emphasized the 

stratigraphical continuity of the Lydite Bed with that at Swindon. 2 

By far the most detailed investigation was made by Prof. A. Morley Davies 

and published in 1899. 3 He described a number of new exposures and above 

all was able to establish three complete vertical sections in the west and 

central parts of the area, at Garsington, Long Crendon and Haddenham, to 

compare with that published by Hudleston for the Aylesbury district in the 

east. The stratal succession was thus established on a sure foundation, and 

in certain localities it was now known in considerable detail. 

Finally S. S. Buckman settled in the district. He made his home at Southfield, 

on the road between Thame and Long Crendon, and so began in earnest 

his incursions into Upper Jurassic stratigraphy. He soon collected a number 

of large ammonites from the pits at Long Crendon, especially one now already 

nearly filled up at Barrel Hill, 4 south of the village, and others north-west of 

the village beside the road to Oakley. In 1922 he published a table of hemerae, 

which was corrected and enlarged in 1926. 5 The quarrymen's terms for the 

beds were listed and almost every bed was assigned a zonal index; in all, the 

Portland Beds of Long Crendon were divided into 23 beds, for which 16 

zonal indices were provided, covering his two Behemothan and Gigantitan 

Ages. At the same time photographs of the ammonites were published in 

Type Ammonites, most of them under not only new specific but also new 

generic names. Buckman explained that this was to be considered, not so 

much a splitting up of previously-existing zones, as an amplification of the 

known zonal sequence. 

In his treatment of the Portland Beds of Long Crendon Buckman displayed 

as clearly as in any part of his work the limitations of the principles which he 

followed, and the illogical results inevitably obtained (both in systematy and 

in stratigraphy) by pursuing them beyond their reasonable capacity. In his 

more cautious youth he would never have pressed sound principles to so 

outrageous a conclusion, but in his old age he seemed to become reckless. 

Every bed that yielded an ammonite became for him a zone, every new thread 

discerned in the mighty tangle of ammonite phylogeny, however slightly 

different it might be from the rest, was for him a new genus. The ordinary 

cautions proclaimed by ecology went unheeded, and the absence of an 

expected ammonite was hailed as infallibly indicating stratal failure. 

A different view has been taken by the most recent reviser of the families of 

ammonites to which those from Long Crendon belong. Dr. L. F. Spath, in 

his monumental work on the Indian and English Cephalopods, states that 

most of Buckman's Portlandian genera are quite unjustifiable, and he believes 

that the diversity of types upon which they are founded constitute a purely 

local English fauna without chronological value. 6 Nevertheless this fauna, 

1 W. H. Hudleston, see bibliography. 

2 H. B. Woodward, 1895,^.^.5., pp. 216-28. 

3 A. M. Davies, 1899, P.G.A., vol. xvi, pp. 15-58. 

4 Not to be confused with Barley Hill, east of Thame, one of Fitton's localities (1836, 

p. 282) now entirely obliterated, which Prof. Davies believes to be located at the rising ground 

north of Kingsey Road, Thame (1899, p. 31). 

5 S. S. Buckman, 1922, T.A.y vol. iv, p. 26; and 1926, vol. vi, p. 35. 

6 L. F. Spath, 1931, Pal. Indica, N.S., vol, ix, p. 472.


local or not, would well repay detailed examination. An interesting work 

awaits any palaeontologist who will undertake to describe and figure it 

systematically (the Portland and Purbeck specimens as well as those from 

Buckinghamshire), for it not only represents the expiring effort in the evolution 

of that almost incredibly diverse family, the Perisphinctidae, but also 

their acme in diversity of form and immensity of size. 

Moreover it must be recognized that Buckman, by his work at Long 

Crendon and by means of his refinement in ammonite identification, achieved 

the correlation of the Oxon.-Bucks. Portland Beds with those of Wilts, and 

Dorset. He showed that the Creamy Limestones contain the same assemblage 

of Titanites ammonites as the Freestone Series of the Isle of Portland; that 

the Rubbly Limestones contain Kerberites kerberus, which characterizes the 

Cockly Bed at Swindon; and that the Glauconitic Beds contain the gorei 

forms (Glaucolithites, &c.) found on the same horizon at Swindon and in the 

top of the Portland Sands of Dorset. 

Thus we are enabled for the first time to give a summary of the Portland 

Beds of Oxfordshire and Bucks, fitted into the classification adopted in the 

type-locality. 

SUMMARY OF THE PORTLAND BEDS IN OXON. AND BUCKS. 1 (fig. 86, p. 506) 

Titanites Zone: Creamy Limestones, 7-12 ft. 

The highest rock in all the quarries was described by Blake as several beds 

of a compacted shell brash, 3-4 ft. thick, having at the bottom of the topmost 

block a number of Trigonice (T. gibbosa). From these beds Buckman figured 

some peculiar ammonites which he did not find at lower horizons. The 

highest 3 ft. at Barrel Hill, Long Crendon, in the quarry now in process of 

being filled up, consisted of four beds with Cadicone Gigantids and was called 

by the quarrymen the Upper Witchett. Beneath was a 2 ft. 6 in. shell-bed 

with massive Gigantids called the Osses Ed. 2 From these beds Buckman 

figured the genotypes and holotypes of the following ammonites: Hippostratites 

hippocephaliticus, 3 H. rhedarius, 4 Glottoptychinitesglottodes, 5 G. audax, 6 

the first from Scotsgrove near Haddenham, the second and third from Barrel 

Hill, and the last from Coney Hill near Over Winchendon. He remarked that 

he had seen nothing comparable with these ammonites among the giants from 

Portland and suggested that the beds yielding them were younger than any 

Portland Beds preserved in Dorset. Perhaps they correspond with the 

Shrimp Bed of Purbeck, in which unidentified ammonites of similar style 

occur (see p. 485). 

The true Creamy Limestones, as originally so-called by Blake, consist of 

some 5 ft.—9 ft. of white, chalky, non-oolitic and highly fossiliferous limestone, 

crowded with Ostrea expansa, Trigonia gibbosa, Protocardia dissimilis 

Ampidlina ceres, &c., and with the usual giant ammonites of the Titanites zone. 

Blake stated that he found Aptyxiella portlandica at one locality, but he 

omitted to mention where. 7 

1 Based on Blake, Hudleston, Woodward, Morley Davies and Buckman, loc. cit. 

2 Horses' Heads is the name given by quarrymen in many parts of England to the casts of 

Trigonice. Plot adopted the name as Hippocephaloides (Nat. Hist. Oxfordshire, 1676, p. 128, 

pi. vii, fig. 1). 

3 T.A., 1924, pi. CDXCV. 4 T.A.y 1924, pi. DXIV. 5 T.A., 1923, pi. CDIII. 

6 T.A., 1927, pi. DCCXVII. 7 1880, loc. cit., p. 217.


According to Buckman certain forms of ammonites at Barrel Hill, Long 

Crendon, are restricted to definite beds, and he lists the workmen's terms 

for the beds and the ammonites derived from them as follows (the 

Roman numerals refer to plates in Type Ammonites in which the forms 

are figured): 

Sandstone . . . I ft. 7 in. with Briareites polymeles (CCLVII). 

[Supposed position of bed at Haddenham with Titanites titan] (CCXXXI). 

Hard Lime . . . 1 ft. 3 in. with Gigantites giganteus (CCLVI). 

Soft Rock . . . . 9 in. with Trophonites trophon (cccxxv 

and CCCXLIII). 

Lower Witchett . 1 ft. o in. with Galbanites fasciger (CDLI) and 

Pleuromegalites forticosta (DXIII). 

Hard Stone . . 1 ft. 3 in. 

Waste . . . . 7 in. 

Bottom Bed or Hard Brown . 1 ft. 2 in. with Vaumegalites vau (DXXXVI). 

It was from this district that the types of the familiar species A. giganteus 

Sowerby and A. pseudogigas Blake came, and Buckman has figured chorotypes. 

1 The new genus Gigantites, which he created for A. giganteus, is 

according to Dr. Spath synonymous with the earlier-named Titanites, and 

the genus Trophonites, to which he assigned A. pseudogigas, Dr. Spath thinks 

may be the same as the earlier-named Kerberites. It is to be noted that 

between 1922 and 1925 Buckman reversed the order of the Titanites and 

Briareites hemerae without explanation. 2 Dr. Spath considers that Galbanites 

as well as the other three genera can be considered synonymous with 

Titanites. 3 

Kerberites Zone: Crendon Sand and Aylesbury Limestone, c. 12-15 ft* 

THE CRENDON SAND, 5-17 ft. 

At the base of the Barrel Hill Quarry, Long Crendon, were 5 ft. of nonglauconitic, 

unfossiliferous, yellowish-brown sands, called by Buckman the 

Crendon Sand. Blake noticed that they are continuous throughout the 

district and occur 'within the limits which we must assign to the Portland 

Stone as distinguished from the Portland Sand 5 . Hudleston and Woodward 

noted them, still 5 ft. thick, at Aylesbury, at the other end of the district (see 

fig. 86), and Fitton described them on the outlier of Stewkley (7 ft. thick). 

In a recent excavation for a new reservoir at the northern extremity of 

Shotover Hill they were considerably thicker and were directly overlain by 

the Shotover Ironsands (Cretaceous). Here they also contained bands of hard 

calcareous, unfossiliferous sandstone, recalling unmistakably the Swindon 

Sand and Stone, with which they are beyond much doubt to be correlated. 

Dr. Pringle noted a similar section in a well at Coombe Wood, on the Shotover 

ridge, and here the thickness of the sand and stone bands (Swindon Stone) 

was 17 ft. He noted them also at the City Farm, where their thickness was 

12-15 ft. 4 

1 T.A.y 1921, pi. CCLVI, and 1923, pi. CCCLXXXV. 

2 Compare T.A.y iv, 1922, p. 26; vol. v, 1925, p. 71; and vol. vi, 1926, p. 35. 


4 J. Pringle, 1926, 'Geol. Oxford', 2nd ed., Mem. Geol. Surv.y pp. 80-1.


THE RUBBLY LIMESTONES OR AYLESBURY LIMESTONE, 1 6-12 ft. 

Blake described the Rubbly Limestones as well displayed in several excavations 

now almost disappeared, at Coney Hill, Quainton, Brill, Lodge Hill 

and Aylesbury railway-cutting. They are still to be seen in the small quarries 

north-west of Long Crendon, beside the road to Oakley, where they were 

described under the quarrymen's terms by Buckman; the thickness here is 

about 7 ft. In 1922 he recorded 'P. gore? from about the middle, but later 

(1925-6) he omitted this record and inserted Kerberites kerberus at the base 

and 'Crendonites' leptolobatus near the top. But Dr. Spath thinks 4 Crendonites' 

is probably synonymous with Glaucolithites, and Buckman's specimen 

was picked up on a heap of quarried stone and has a slightly glauconitic 

matrix, and so it may have come from the Glauconitic Beds. 2 

In the recent excavation for the reservoir on Shotover Hill a large quantity 

of the Rubbly Limestones was thrown out. The material, in the identity and 

state of preservation of its fossils as well as in its lithic appearance, bore 

a striking resemblance to the Cockly Bed of Swindon. Dr. J. A. Douglas and 

Mr. C. J. Bayzand obtained a number of the large ammonites comparable 

with those from the Cockly Bed, and it is hoped that a publication will soon 

appear on the subject. A similar fauna was collected by Hudleston from 

material thrown up during drainage operations near the George Hotel, 

Aylesbury. 

Blake noticed that at Coney Hill many of the fossils seemed to have been 

derived, for their matrix differed from that of the surrounding Rubbly Limestone. 

Glaucolithites Zone: Glauconitic Beds and Upper Lydite Bed, 5-10 ft. 

Over the whole area the base of the Portland Beds consists of 5-10 ft. of 

highly glauconitic, green, rubbly, sandy limestone and sand, with the Upper 

Lydite Bed at the bottom, resting upon the Pavlovia zones of the Kimeridge 

Clay (or the Thame Sands; see p. 466). Two of the best sections, described 

by Hudleston, were the pits in the Hartwell Clay at Hartwell and Bierton, 

near Aylesbury, where the Lydite Bed is unusually thick and fossiliferous. 

A cutting on the Metropolitan Railway at Walton proved the sand and Lydite 

Bed to be 10 ft. thick. 3 Another good section may now be seen on Shotover 

Hill, since the large quarry in the Shotover Grit Sands has recently been enlarged 

farther into the hill and displays the Swindon Clay with the lower 

Lydite Bed below and the Upper Lydite Bed above, overlain by the Glauconitic 

Beds. 

Buckman has investigated the ammonite fauna of the Glauconitic Beds in 

the quarries north-west of Long Crendon and he records the following 

succession, using again the quarrymen's terms and introducing a number of 

new genera. As these have not yet been revised, I give the original names. 

1 The name Aylesbury Limestone was introduced by Fa rev in 1811 (teste IT. B. Woodward, 

1895,^.^.5., p. 224). It was also used by Conybeare and Phillips in their Geology of England 

and Wales, 1822 (map and sections). 

2 T.A., 1923, pi. CDI; and 1926, vol. vi, p. 35. 

3 C. P. Chatwin and J. Pringle, 1922, 'Geol. Aylesbury', Mem. Gent. Surv., p. 6, Bed 1. 

(Presumably Bed 2 Rubbly Limestone, 8 ft.; Bed 3 -= Crendon Sands, 5 ft.; Bed 4 —• 

Creamy Limestones, 5 ft. 8 in., overlain by Gault.)


According to Buckman certain forms of ammonites at Barrel Hill, Long 

Crendon, are restricted to definite beds, and he lists the workmen's terms 

for the beds and the ammonites derived from them as follows (the 

Roman numerals refer to plates in Type Ammonites in which the forms 

are figured): 

Sandstone . . . I ft. 7 in. with Briareites polymeles (CCLVII). 

[Supposed position of bed at Haddenham with Titanites titari\ (ccxxxi). 

Hard Lime . . . 1 ft. 3 in. with Gigantites giganteus (CCLVI). 

Soft Rock . . . . 9 in. with Trophonites trophon (cccxxv 

and CCCXLIII). 

Lower Witchett . . 1 ft. o in. with Galbanites fasciger (CDLI) and 

Pleuromegalites forticosta (DXIII). 

Hard Stone . . . 1 ft. 3 in. 

Waste . . . . 7 in. 

Bottom Bed or Hard Brown . 1 ft. 2 in. with Vaumegalites vau (DXXXVI). 

It was from this district that the types of the familiar species A. giganteus 

Sowerby and A. pseudogigas Blake came, and Buckman has figured chorotypes. 

1 The new genus Gigantites, which he created for A. giganteus, is 

according to Dr. Spath synonymous with the earlier-named Titanites, and 

the genus Trophonites, to which he assigned A. pseudogigas, Dr. Spath thinks 

may be the same as the earlier-named Kerberites. It is to be noted that 

between 1922 and 1925 Buckman reversed the order of the Titanites and 

Briareites hemerae without explanation. 2 Dr. Spath considers that Galbanites 

as well as the other three genera can be considered synonymous with 

Titanites. 3 

Kerberites Zone: Crendon Sand and Aylesbury Limestone, c. 12-15 ft. 

THE CRENDON SAND, 5-17 ft. 

At the base of the Barrel Hill Quarry, Long Crendon, were 5 ft. of nonglauconitic, 

unfossiliferous, yellowish-brown sands, called by Buckman the 

Crendon Sand. Blake noticed that they are continuous throughout the 

district and occur 'within the limits which we must assign to the Portland 

Stone as distinguished from the Portland Sand'. Hudleston and Woodward 

noted them, still 5 ft. thick, at Aylesbury, at the other end of the district (see 

fig. 86), and Fitton described them on the outlier of Stewkley (7 ft. thick). 

In a recent excavation for a new reservoir at the northern extremity of 

Shotover Hill they were considerably thicker and were directly overlain by 

the Shotover Ironsands (Cretaceous). Here they also contained bands of hard 

calcareous, unfossiliferous sandstone, recalling unmistakably the Swindon 

Sand and Stone, with which they are beyond much doubt to be correlated. 

Dr. Pringle noted a similar section in a well at Coombe Wood, on the Shotover 

ridge, and here the thickness of the sand and stone bands (Swindon Stone) 

was 17 ft. He noted them also at the City Farm, where their thickness was 

12-15 ft. 4 

1 T.A.t 1921, pi. cclvi, and 1923, pi. ccclxxxv. 

2 Compare T.A., iv, 1922, p. 26; vol. v, 1925, p. 71; and vol. vi, 1926, p. 35. 


4 J. Pringle, 1926, 'Geol. Oxford', 2nd ed., Mem. Geol. Surv., pp. 80-1.


THE RUBBLY LIMESTONES OR AYLESBURY LIMESTONE, 1 6-12 ft. 

Blake described the Rubbly Limestones as well displayed in several excavations 

now almost disappeared, at Coney Hill, Quainton, Brill, Lodge Hill 

and Aylesbury railway-cutting. They are still to be seen in the small quarries 

north-west of Long Crendon, beside the road to Oakley, where they were 

described under the quarrymen's terms by Buckman; the thickness here is 

about 7 ft. In 1922 he recorded 'P. goreV from about the middle, but later 

(1925-6) he omitted this record and inserted Kerberites kerberus at the base 

and 'Crendonites > leptolobatus near the top. But Dr. Spath thinks 4 Crendonites' 

is probably synonymous with Glaucolithites, and Buckman's specimen 

was picked up on a heap of quarried stone and has a slightly glauconitic 

matrix, and so it may have come from the Glauconitic Beds. 2 

In the recent excavation for the reservoir on Shotover Hill a large quantity 

of the Rubbly Limestones was thrown out. The material, in the identity and 

state of preservation of its fossils as well as in its lithic appearance, bore 

a striking resemblance to the Cockly Bed of Swindon. Dr. J. A. Douglas and 

Mr. C. J. Bayzand obtained a number of the large ammonites comparable 

with those from the Cockly Bed, and it is hoped that a publication will soon 

appear on the subject. A similar fauna was collected by Hudleston from 

material thrown up during drainage operations near the George Hotel, 

Aylesbury. 

Blake noticed that at Coney Hill many of the fossils seemed to have been 

derived, for their matrix differed from that of the surrounding Rubbly Limestone. 

Glaucolithites Zone: Glauconitic Beds and Upper Lydite Bed, 5-10 ft. 

Over the whole area the base of the Portland Beds consists of 5-10 ft. of 

highly glauconitic, green, rubbly, sandy limestone and sand, with the Upper 

Lydite Bed at the bottom, resting upon the Pavlovia zones of the Kimeridge 

Clay (or the Thame Sands; see p. 466). Two of the best sections, described 

by Hudleston, were the pits in the Hartwell Clay at Hartwell and Bierton, 

near Aylesbury, where the Lydite Bed is unusually thick and fossiliferous. 

A cutting on the Metropolitan Railway at Walton proved the sand and Lydite 

Bed to be 10 ft. thick. 3 Another good section may now be seen on Shotover 

Hill, since the large quarry in the Shotover Grit Sands has recently been enlarged 

farther into the hill and displays the Swindon Clay with the lower 

Lydite Bed below and the Upper Lydite Bed above, overlain by the Glauconitic 

Beds. 

Buckman has investigated the ammonite fauna of the Glauconitic Beds in 

the quarries north-west of Long Crendon and he records the following 

succession, using again the quarrymen's terms and introducing a number of 

new genera. As these have not yet been revised, I give the original names. 

1 The name Aylesbury Limestone was introduced by Farey in 1811 (teste H. B. Woodward, 

i 895, J.R.B., p. 224). It was also used by Conybeare and Phillips in their Geology of England 

and Wales, 1822 (map and sections). 

2 T.A.y 1923, pi. CDI; and 1926, vol. vi, p. 35. 

3 C. P. Chatwin and J. Pringle, 1922, 'Geol. Aylesbury', Mem. Geol. Surv., p. 6, Bed 1. 

(Presumably Bed 2 = Rubbly Limestone, 8 ft.; Bed 3 = Crendon Sands, 5 ft.; Bed 4 = 

Creamy Limestones, 5 ft. 8 in., overlain by Gault.)

5i4 UPPER OOLITES 

(Rubbly Limestones above.) 

Green Specked Bed . . 9 in. with Polymegalites polypreon (cf. DXCI). 

Brown layer . . . 3 in. 

Green marl 

(ammonites in white matrix) 8 in. with Leucopetrites leucus (cccvn a-c). 

Building Stone (glauconitic) . 3 ft. o in. with Glaucolithites glaucolithus (cccvi). 

Waterstone . . . 10 in. with Aquistratites aquator (DXXXIV) and 

Hydrostratites bifurcus (DCLXXVI). 

Lydite Bed . 5 in. with 'Lydistratites' lyditicus ( = derived 

Pavlovids). 

(Thame Sands below.) 

In addition to these ammonites he figured from the Glauconitic Beds of 

Haddenham the genoholotype of Behemoth megasthenes 1 and from Thame 

B. lapideus. 2 

The Upper Lydite Bed provides one of the most constant and most useful 

datum lines for the correlation of the Portland Beds from Aylesbury to the 

Vale of Wardour. Its essential contemporaneity was insisted upon first by 

Hudleston, then by Woodward, and more recently by Prof. Davies. 

'There are certain general reasons', wrote the last, 'why a pebble-bed of this kind 

should be a more trustworthy indication of a definite horizon than a line of lithological 

change.... Such a bed, especially when continuous over a large area, betokens 

most probably an interruption of normal sedimentation for a time by the action of 

a current—some of the fine material previously deposited being probably swept 

away at the beginning of the current-phase, while at the end of that phase the first 

slackening in the current would cause a deposition of pebbles previously swept to 

and fro, and then the deposit of fine material would be resumed.' 3 

Prof. Davies found among the usual fragments of black chert constituting 

the bulk of the 'lydites' at Garsington several pebbles of spherulitic felsite and 

one of phosphatized bone. Later he recorded also a fragment of a phosphatized 

ammonite at Dadbrook Hill near Haddenham. 4 More recently a detailed 

study has been devoted to the bed by Dr. Neaverson. 5 He divides the pebbles 

into two sorts, those of local origin, and those which are far-travelled. The 

pebbles of the first category are highly phosphatic, containing as much 

as 56 per cent, of calcium phosphate; they comprise phosphatic casts of 

lamellibranchs and Pavlovid ammonites, dull black in colour, composed 

of clear quartz grains, with occasional grains of glauconite, set in a brown 

matrix. The ammonites have for the most part been washed out of the 

underlying Hartwell or Swindon Clay and are thus derived, though not in 

the sense of Dr. Neaverson's more distantly derived pebbles of the other 

category. 

The pebbles brought into the district from a distant source consist mainly 

of black chert, and in some of them Dr. Neaverson found spicules of Hyalostelia, 

a sponge found in the Lower Carboniferous Beds of Scotland, Yorkshire, 

North Wales and Ireland. Besides the cherts, there are a number of 

fragments of vein quartz and some, of especial interest, of silicified oolite. 

These may also be regarded as a chert, with ooliths which have been nearly 

1 T.A., 1922, p. cccv. 2 T.A.y 1922, pi. CCCXLII a-c. 


4 Ibid., pp. 20, 158. 

5 E. Neaverson, 1925, P.G.A., vol. xxxvi, pp. 245-6.

PORTLAND BEDS: KENT 515 

obliterated during silicification. Similar pebbles occur in the Lower Greensand 

of Faringdon, and in boulders derived from the Lower Greensand in 

Glacial deposits near Quainton. Their origin is problematic, but again the 

existing occurrences of silicified oolite, like those of spicular chert, are in the 

North-West Highlands of Scotland (Torridonian and Cambrian) and South 

Wales (Carboniferous). 

These considerations, taken in conjunction with the failure of the lydites 

in Dorset, lead Dr. Neaverson to postulate a northerly origin for the pebbles. 

That they were derived originally from some part of the Caledonian mountain 

chain seems highly probable, but they may have come from a part of the 

chain lying to the east of the British Islands; and they may have travelled 

south in late Palaeozoic or Triassic times and have been rederived during the 

Jurassic period from the London-Ardennes landmass or its extension under 

the North Sea. 1 

IV. KENT 2 

No Portland Beds are known to exist in the British Isles north of the last 

faulted outlier at Stewkley, near Leighton Buzzard. An idea formerly 

prevalent (introduced by Pavlow), and reiterated even in certain recent textbooks, 

that equivalents of the Portland Beds exist in the Speeton Clay of 

Yorkshire, has been dispelled by recent work (see above, p. 472). Another 

basin of deposition, however, or more probably a continuation of the Dorset 

trough, has been proved by the borings beneath the Weald of Kent. The 

Portland Beds were penetrated in at least six places, four of them in a straight 

line running nearly west to east from Tonbridge towards Dover, and the rest 

near Battle, on the south of the Weald. 

Lithologically the rocks are markedly different from those in Dorset and 

accurate correlation of the subdivisions, with the limited palaeontological 

evidence supplied by the cores, was impossible. The Portland Stone was 

found to be much more sandy than in Dorset and there was no suggestion of 

a Freestone Series or a Cherty Series. The Portland Sand, on the other hand, 

was more argillaceous and graded down so imperceptibly into the Kimeridge 

Clay that for convenience it had to be classed with the Upper Kimeridge 

Clay, no separation being practicable. For these reasons the over-all thickness 

of the Portland Beds as defined in this chapter cannot be ascertained from the 

records. 

It was found that the stone-beds were thickest in the west, at Penshurst 

boring, south-west of Tonbridge, where they attained a thickness of 131 ft., 

and at Battle, where supposedly the same beds reached 141 ft. Eastward they 

thinned rapidly. At Pluckley and Brabourne, two borings nine miles apart, 

west and east of Ashford, proved thicknesses of 70 ft. and 30 ft., while at 

Ottinge, midway between Ashford and Dover, only 17 ft. were left. At the 

first four places Purbeck Beds capped the Portlands, but at Ottinge the Purbecks 

had been cut out by an unconformable overstep of the Wealden Beds, 

and an unknown thickness of Portland Stone may also have been missing. In 

a boring still farther east, at Dover, the Wealden Sands had crossed both 

1 See W. J. Arkell, 1927, Phil. Trans. Roy. Soc.y vol. ccxvi B, pp. 80-2, where this problem 

is discussed in connexion with the similar lydite pebbles in the Lower Calcareous Grit. 


1923, loc. cit.


Purbeck and Portland Beds and had come to rest on the Lower Kimeridge 

Clay. 

The borings at Penshurst and Battle, which penetrated the fullest sequence, 

provide the best illustration of the development in Kent. The Lower Purbeck 

Beds at Penshurst, consisting here of gypsiferous marlstone, were separated 

from the Portland Beds, the top composed of a calcareous sandstone full of 

marine fossils, by a sharp line of demarcation, wanting, however, in any signs 

of erosion. Only the highest 6 ft. of the Portland Stone contained sufficient 

calcareous matter to be entitled a sandy limestone. It abounded in such 

fossils as Chlamys lamellosa, Trigonia gibbosa and Isognomon bouchardi. The 

sandstone below this, according to Lamplugh, 

4 for the next 6o ft. . . . was much less limy and yielded comparatively few fossils, 

being a massive homogeneous rock with the bedding planes very feebly developed. 

At lower depths the bedding became more pronounced again, being often accentuated 

by clayey streaks; and the sandstone also (as at Pluckley) included hard 

calcareous bands containing many fossils. These beds merged gradually downward 

into sandy shale, which formed an unbroken passage into the Kimmeridge Clay.' 1 

The lowest 6 ft. of strata grouped with the Portland Beds were described 

as 'dark grey, sandy, calcareous shale with a few obscure fossils, chiefly Ostrea, 

Pecten, See., passing down gradually into dark blue clay of Kimmeridge type 5 . 2 

Beneath this were 185 ft. of dark blue and paler grey clay with bands of 

calcareous claystone at intervals, some of them nodular, and containing 

Lingula oralis, Modiola autissiodorensis, &c., before really shaly and black clays 

were reached. Evidently a great part of this, if not all of it (Messrs. Kitchin 

and Pringle have suggested 100 ft.), corresponds to the Portland Sand of 

Dorset as defined above, but it is quite impossible to say where the line of 

separation should be drawn. Ammonites suggestive of the Pavlovia zones 

were met with about 215 ft. below the base of the stone. 

In the Pluckley boring, about 5 miles west of Ashford, the succession was 

identical, except that the Portland Stone was only 70 ft. thick, and an ammonite, 

which may indicate the Pavlovia zones, was met with only 131 ft.below 

the stone. 

At Brabourne, about the same distance east of Ashford, great changes had 

set in. Here the stone-beds were only 31 ft. thick, although the Purbeck Beds 

were still present above. They could be roughly divided into three blocks. 

At the top were 11 ft. of greyish-yellow sandy limestone with many Serpulce 

and casts of bivalves, and a fragment of a large ammonite. The fossils were 

the same as in the upper portion at Penshurst and Pluckley. Below came 16 ft. 

of greenish-grey sandy mudstone and semi-indurated calcareous sandstone, 

again with Serpulce. and casts of bivalves. At the base, 4 ft. of hard conglomeratic 

rock rested abruptly on dark, highly fossiliferous shaly clay with 

ammonites of the Pavlovia zones. 

At Ottinge, still farther east, where the Wealden Beds had cut down unconformably 

upon them, only 17 ft. of the Portland Beds were left. The whole 

of this consisted of glauconitic sand and sandstone, and it rested abruptly on 

hard dark Kimeridge Clay, evidently with an even more pronounced nonsequence 

than that revealed at Brabourne. 

1 G. W. Lamplugh, 1911, loc. cit., p. 76. 

2 Ibid., p. 75.

PORTLAND BEDS: KENT 517 

Messrs. Lamplugh, Kitchin and Pringle considered that the non-sequence 

here excluded not only the greater part of the pallasioides zone and the overlying 

'passage-beds' but also the whole of the equivalents of the Portland Sand 

of Dorset, and in addition some basal portion of the Portland Stone (about 

300 ft. of strata at Penshurst). No lydite pebbles were reported from any of 

the borings, but in view of the 'conglomeratic or brecciated appearance' 1 

of the basement-bed at Brabourne and the presence of glauconite, so conspicuous 

at Ottinge, it is tempting to suppose that the transgressive stratum 

is on the horizon of the Upper Lydite Bed and Glauconitic Beds of Wiltshire, 

Oxon. and Bucks. If this is so, then there was on both sides of the London- 

Ardennes ridge an overstep at about the same time, and a simultaneous 

appearance of glauconite in the sediment. By such a correlation, the magnitude 

of the non-sequence in Kent is somewhat reduced, for the Glauconitic 

Beds and Upper Lydite Bed of the Midlands undoubtedly represent an upper 

portion of the Portland Sand of Dorset. 

A feature of the Portland Stone in Kent, possibly of secondary origin, but 

none the less remarkable, was the impregnation of the stone with bitumen. 

In some of the borings it was so abundant that it had collected in the joints 

and other crevices in thick drops. In North-West Germany, also, the presumed 

equivalent of the Portland Beds, the 100 ft.-thick Eimbeckhauser 

Plattenkalk Series, is highly bituminous. Although shales are often bituminous, 

it is a rare feature in limestones and sandstones. 

Ibid., p. 44.

CHAPTER XVI 

PURBECK BEDS 

Divisions. Ostracod Zones (PI. XLI). | Strata in Durlston Bay. Thickness. j 

UPPER Cypridea punctata 

and C. ventrosa 

MIDDLE . 

i 

i 

Sub zone. 

Cypridea granulosa 

var. fascicidata 

and 

Metacypris forbesii 

; Cypris purbeckensis 

LOWER and 

i Candona ansata. 

Viviparus Clays 

Marble Beds and 

Ostracod Shales 

Unio Beds 

Broken Shell 

Limestone 

Chief Beef Beds 

Corbula Beds 

Upper Building Stones 

Cinder Bed 

Lower Building Stones 

| Mammal Bed 

| Marls with Gypsum 

| and Insect Beds 

, Broken Beds 

Caps and Dirt Beds 

ITT+oi 

10' 

30; 

3 4 - 1 

3F, i 

I 72'( + ) 

1 135' 

j 15' | W 

j 19' ! 

T HE last phase of the Jurassic period, represented by the Tithonian Stage 

in Southern Europe where normal marine sedimentation continued, saw 

a profound change over the British area. The sea retreated, leaving swamps 

and lakes, in which a freshwater fauna flourished from Dorset to Buckinghamshire 

and Kent. Ammonites became extinct in the area, not to reappear until 

brought in with the Cretaceous transgressions. 

Minor oscillations lifted the surface temporarily into dry land, on which 

Coniferous and Cycadean forests took root and flourished, providing a habitat 

for insects and, most important of all, for small mammals and reptiles, whose 

bones became interred in the land soils and lacustrine muds. The sea remained 

not far distant, however, for periodically the fresh and brackish-water 

fauna or land flora was replaced by a marine assemblage comprising such 

familiar genera as Ostrea, Trigonia, Modiola, Thracia, Isognomon and Hemicidaris. 

The most important of these transgressions left evidence that it 

affected Dorset, Sussex, Kent and South Wiltshire. In Dorset and in the Vale 

of Wardour was formed an oyster-bank like those in the Portland Beds, 

locally S-\- ft. thick, composed of Ostrea distorta Sow. The other marine invasions 

were relatively minor episodes in a long period of lacustrine or mud-flat 

and swamp conditions, under which great accumulations of banded shales, 

clays and thin^bedded limestones were built up, often crowded with Ostracods 

and small freshwater molluscs, such as Viviparus and Unio. 

These deposits together form the Purbeck Beds, which in the type-locality 

in Dorset attain a maximum thickness of 400 ft. and under the Weald of Kent 

reach no less than 560 ft. Superficially, as noted by several geologists, they 

bear an unmistakable resemblance to the Rhaetic Series: banded clays and 

shales, fine-grained white limestone like W T hite Lias, laminated insect-beds

PURBECK BEDS 519 

and even arborescent stone resembling Cotham Marble, all are found in the 

Purbeck Beds. It would thus appear that the sedimentary conditions under 

which the Jurassic period in the British area opened were to some extent 

repeated in its closing phase. 

It is not easy to subdivide the Purbeck Beds, or to correlate the subdivisions 

in different parts of England. Lithologically there is little by which to be 

guided, for the many types of rock alternate rapidly in short distances. This 

is not surprising in view of the probable mode of formation of the deposits, in 

changing and often separate basins covered by shallow water, now open to the 

sea, now cut off from it by shifting sand or mud bars. The palaeontology at 

first sight likewise affords few criteria, for the freshwater mollusca are the 

same from base to summit, the assemblages at successive levels differing only 

in the relative abundance of certain species—differences of no use in making 

correlations over any but small areas. 

The deficiency left by the macroscopic fauna, however, is made good by the 

Ostracoda. The study of these minute Crustacea in situ in the cliffs of Dorset 

was begun by Edward Forbes, who based on them a tripartite subdivision of 

the beds, which he published in 1S50. 1 The subdivisions were at the same 

time accurately defined by Bristow, who mapped the Isle of Purbeck and 

measured the sections in great detail. 2 Unfortunately Forbes did not live to 

fulfil his intention of monographing the Purbeck invertebrate fauna, but the 

study of the Ostracods was taken up, with important results, by the late 

Prof. T. Rupert Jones. 

Prof. Jones described and figured all the known Ostracods from the English 

Purbecks and determined as accurately as possible their range. He concluded 

as follows: 

'There are fourteen species of Ostracoda in E. Forbes' three divisions of the 

Purbeck series of deposits. Five of them occur only in the Lower Purbeck. Of the 

others, six occur in both the Middle and the Upper. . . . Cypridea punctata for 

the Upper, C. granulosa (fasciculata) for the Middle, and Cypris purbeckensis 

for the Lower Purbeck, are especially characteristic.' 3 

Since this passage was written some authors have promoted several of 

Jones's varieties to new species, but his general conclusions as to their range 

have been found to hold, not only for Dorset, but also for the inland localities. 

Andrews and Jukes-Browne early applied Forbes's and Jones's classification to 

the Vale of Wardour Purbecks, with marked success, the Ostracods enabling 

them to prove that all three subdivisions are there represented. Detailed 

collecting by Prof. Morley Davies and still more recently by Mr. E. A. 

Merrett has shown that two zones of Ostracods can be recognized also in 

Buckinghamshire, although the strata are greatly reduced in thickness; the 

lower zone there represents the Lower Purbeck Beds and the higher zone the 

Middle and perhaps also the Upper Purbeck of Dorset. In N.W. Germany, 

550 miles away, Koert has proved the same succession and established all three 

divisions (see next chapter, p. 551). 

So much work has now been successfully done on the Purbeck Ostracods 

1 E. Forbes, 1850, Edinburgh Phil. Journ., vol. xlix, pp. 311-13, 391 ; and 1851, Rept. Brit. 

Assoc. for 1850, pp. 79-81. 

2 H. W. Bristow, Vertical Sections Geol. Survev, sheet 22, No. 1. 

3 T. R. Jones, 1885, Q.J.G.Svol. xii, p. 331. *


that it seems justifiable to accept their chronological value as established. It 

does not seem practicable, however, to distinguish more than two major zones. 

The upper corresponds with the range of Cypridea punctata (Forbes) and 

C. ventrosa Jones, embracing the Upper and Middle Purbeck of Forbes. 1 

The lower zone is defined by the range of the five species enumerated by 

Jones, and of them may be chosen as zonal indices the two most typical and 

abundant, Cypris purbeckensis Forbes and one of the two common species of 

Candona, C. ansata Jones or C. bononiensis Jones (see PL XLI). 

Two species seem to be confined to the Middle Purbeck, Cypridea granulosa 

(Sow.) (especially its more common variety, var. fasciculata Forbes) and 

Metacypris forbesii Jones. But since both of these occur within the range of 

Cypridea punctata and C. ventrosa, they do not indicate more than a subzone. 

In contrast to the advanced state of our knowledge of the Ostracoda, the 

rest of the invertebrate palaeontology remains in much the same position as 

seventy years ago. A revision of the mollusca is badly needed, but the continued 

neglect of the subject is fostered by the unattractive condition of the 

material. Much patience would be required to procure specimens of all the 

species fit for photography and description. 

The vertebrate fauna has fared better, as its extreme importance to palaeontology 

(but not to stratigraphy) merited. The mammals, reptiles and fishes 

are known the world over, and a voluminous literature has grown up about 

them. Even since the Great War revisionary monographs have appeared upon 

the fishes by Sir Arthur Smith Woodward and upon the mammals by Dr. 

G. G. Simpson. The vertebrate fossils will be noticed in the following pages 

when the type localities are described. 

I. DORSET 

(a) The Isle of Purbeck 

The Purbeck Beds of the Isle of Purbeck give rise to a grassy upland, 

partitioned by stone walls, and simulating an outlying fragment of the Cotswold 

Hills. The outcrop is widest in the east, about the quarrying centres of 

Swanage, Langton and Worth, where the Portland Stone lies deep underground, 

only appearing above the surface along the south coast of the peninsula. 

Above the vertical cliffs of Portland Stone described in the last chapter 

the softer Purbecks rise in steep grassy and flowery slopes to a general height 

of 400 ft., clad during the summer in scabius, rest-harrow, pyramid orchis 

and bee orchis, and the closer turf at the top carpeted with thyme and blue, 

pink, and white veronica. 

The hills are scarred with innumerable old quarries and the tip-heaps from 

abandoned shafts, which, with the remains of ancient quarrymen's shelters 

overgrown with brambles, suggest to a new-comer to the district the site of 

some ruined town of remote antiquity. 

These relics scattered all over Purbeck mark the site of one of the oldest 

stone-quarrying industries in the country. Purbeck Stone, together with the 

Portland Stone mined in the cliffs and now called Purbeck-Portland, were 

transported far and wide as building materials long before the stone of Port- 

1 C. dunkeri Jones is unsuitable as a zonal index, for it ranges up into and abounds in the 

Wealden Beds in Kent.

PURBECK BEDS: PURBECK COAST 521 

land Island had acquired fame through Wren's selecting it for the rebuilding 

of St. Paul's. Purbeck Marble also, which is a freshwater limestone made up 

of myriads of Viviparus [Paludina] shells, was transported to Scotland, 

Ireland and the Continent for church decoration in the Middle Ages. The 

causes of its demand were its green (and occasionally red) mottled colouring 

and its property of taking a high polish. The most striking and extensive use 

to which it has been put is probably in the interior decoration of Salisbury 

Cathedral, where the dark green, slender detached shafts of the columns and 

windows are of marble, contrasting strongly with the white background of 

freestone. This building testifies to an active quarrying industry in Purbeck 

at least as early as 1258. After a life of some 700 years, or more, the industry 

seems at last to have died out, killed by the importation of more varied and 

more durable true marbles from Italy. 1 

The quarrying of the Purbeck Stone still continues, and is still largely in 

the control of the closed guild who have handed down the tradition from 

father to son from time immemorial. To the stone industry has been directly 

due the growth of Swanage. More recently, however, since the exploits of 

George the Third at Weymouth introduced the cult of sea bathing, the little 

stone-mining village has found in its golden sands a new and more valuable 

asset, and the austerities of its earlier development are becoming so thoroughly 

masked that they will soon be forgotten. 

Several complete sections of the Purbeck Beds are afforded by the cliffs 

from Swanage to beyond Lulworth. The finest is that in Durlston Bay (fig. 87) 

to the south of Swanage, where the formation attains its maximum thickness 

in Dorset of 400 ft.; most of the sequence is repeated by a fault in the centre 

of the bay. Westward from Durlston Head, past Dancing Ledge, Seacombe 

and Winspit to St. Alban's Head, the basement-beds and the abrupt junction 

with the Portland Stone are seen discontinuously in the brow of the cliffs, 

while inland along the same length of outcrop many small sections of the 

middle and upper parts of the series are afforded by the quarries and stone 

mines. The next complete section is seen on the south side of Worbarrow 

Bay, in the small peninsula of Worbarrow Tout and the adjoining Pondfield 

Cove (Pl.XXVII); here the total thickness has shrunk by more than a quarter 

to 290 ft. Towards the west the strata become more and more steeply inclined 

as they approach nearer to the Purbeck Thrust Fault, and this contributes 

even more than the diminution in thickness to the narrowing of the outcrop. 

West of Worbarrow Tout the outcrop lies for the most part beneath the sea, 

but several disconnected stretches remain on either side of Lulworth, protected 

on their seaward side by bulwarks of Portland Stone. The longest runs 

from the south side of Mupe Bay, where outliers cap the stacks of Portland 

Stone called the Mupe Rocks, to Lulworth Cove. Here are some of the best 

of all the sections of the Purbeck Beds, especially in Bacon Hole, a cove 

immediately west of the Mupe Rocks, and at the famous Fossil Forest between 

Bacon Hole and Lulworth (PL XXVII). The total thickness still further 

diminishes, from 250 ft. at Mupe Bay to 176 ft. at Lulworth Cove (map, p. 442). 

1 The last building in which any extensive use was made of the marble was the Eldon 

Memorial Church at Kingston, near Corfe Castle, opened in 1880; large quantities were 

employed for facing the columns of the colonnades in the nave, for the chancel screen and 

the window pillars, and the result is extremely pleasing. The pits were opened in a field at 

Blashenwell Farm, north of the village.

BECKLES OLD 

MAMMAL QUARRY PEVERIL POINT 

COASTGUARD 

HUT 

FIG. 87. Type-section of the Purbeck Beds in Durlston Bay, Swanage. Distance 1 mile. (After A. Strahan.) 

f 13 Purbeck Marble Beds and Ostracod Shales at- 1 11 t> u if 7 Lower Building Stones, with flint at base (6) 

Upper Purbeck


West of Lulworth Cove the beds are much contorted, as is shown in the 

well-known section in Stair Hole, so often portrayed by pen and camera. 

The last remaining fragment forms the neck of the Promontory of Durdle 

Door, where the beds, being close beneath the Thrust Fault, seen in the Chalk 

cliff of the adjoining mainland, stand vertically (PI. XXVIII). The extreme 

thinness of the formation here, and to a lesser extent also at Stair Hole, is due 

to the squeezing out of the clays, for much of the Gault also is missing. 

SUMMARY OF THE PURBECK BEDS OF PURBECK 1 

Zone of Cypridea punctata and C. ventrosa: Upper Purbeck, 27-70 ft.+ 

VIVIPARUS CLAYS, I ft.-II ft.? 

The highest beds of all consist of blue, green, grey and purple marls and 

sandy shale with fish-remains, Viviparus and Ostracods. These beds are not 

seen at Swanage, where the junction with the Wealden Series is concealed by 

the harbour and town, as well as by alluvium. At Worbarrow also it is obscured 

by the stream that enters the sea near the boat-house. At Mupe Bay 

it can be clearly studied, however, and the passage to the Wealden is perfectly 

conformable and gradual; the thickness of the Viviparus Clays there is 11 ft. 

MARBLE BEDS AND OSTRACOD SIIALES [Upper Cypris Shales], 17-46 ft. 

Near the top of this division are the two chief bands of Purbeck Marble, 

one red and the other green, composed of Viviparus cariniferus and V. 

elongatus. A short distance below is a tough bed of greenish sandy limestone 

with Unio (the Unio Bed). These hard bands crop out at Peveril Point, where 

they run for a mile out to sea and form some of the ledges upon which the 

Danish fleet is supposed to have been wrecked in the year 877. Inland they 

run along the High St., and outside the town they can be traced at the junction 

of the vale and the hills by a line of old marble workings, overgrown with 

woods and thickets. Below and between the limestones are clays, shales with 

'beef', red and green marls, and thin seams of limestone, some of which are 

made up almost entirely of the minute valves of Ostracods. A piece of one of 

the Ostracod-limestones has been figured by Chapman, 2 who states that the 

species, in order of abundance, are Cypridea punctata (Forbes), C. posticalis 

Jones and C. ventrosa Jones; Darwimda leguminella, fish-remains and coprolites 

are also found. 

UNIO BEDS, 5 ft. 9 in.-4 ft. 9 in. 

The name Unio Beds is given to a thin series of clays with occasional beef 

and bands of greenish limestone containing Unio, but not so conspicuously 

as in the Unio Bed higher up. One band of carbonaceous limestone has 

yielded crocodilian remains in Durlston Bay and has been called the Crocodile 

Bed. Other fossils are remains of fish and turtles, coprolites, Cypridea punctata, 

Viviparus, and the freshwater bivalve Neomiodon ['Cyrena' auct.]. One 

of the best sections of the Unio Beds is to be seen on the north side of Worbarrow 

Tout, close to the beach, near the boat-house. 

1 Based on H. B. Woodward, 1895 J.R.B., pp. 243-56; and A. Strahan, 1898, 'Geol. Isle 

of Purbeck and Weymouth', pp. 91-103, Mem. Geol. Surv.; thicknesses by H. W. Bristow. 

Alterations have been introduced in nomenclature. 

2 F. Chapman, 1906, P.G.A., vol. xix, pi. v, p. 283.


BROKEN SHELL LIMESTONE OR BURR, 3 ft. 9 in -10 ft. 

This limestone, largely made up of comminuted shells of Neomiodon and 

Unio, with Limncea, Viviparus and fish-remains, is 10 ft. thick at Peveril 

Point, where it forms the most northerly of the reefs. It also forms the 

shelving platform along the shore below the Grosvenor Hotel, where it contains 

curious round depressions noticed a hundred years ago by Fitton, but 

not yet satisfactorily explained. 1 

Subzone of Cypridea granulosa and Metacypris forbesii: Middle Purbeck, 

55-157 ft. 

CHIEF BEEF BEDS, 8-30 ft. 

Dark shales with much 'beef' and selenite, with beds of limestone and 

layers of perished shells of Neomiodon; also Cypridea. 

CORBULA BEDS, I&~34 ft. 

Layers of shelly limestone, shale and marl, with beef and selenite, and 

marine molluscs: Corbula spp., Modiola, Ostrea, 'Pecten', Isognomon, Thracia, 

Protocardia; also Melanopsis harpceformis, Neomiodon, turtle- and fish-remains, 

insects and Ostracods. The Corbula Beds contain more limestone than the 

Chief Beef Beds, but otherwise there is no essential difference in the lithology. 

The species recorded from the Middle Purbeck of Swanage by Koert are 

Corbula alata Sow., C.forbesi De Lor., C. infiexa Roemer and C. durlstonensis 

Maillard. 2 

UPPER BUILDING STONES, 8^-50 ft. 

The Purbeck building-stones are not a strictly-defined stratigraphical unit, 

for towards the west end of the promontory they are in part replaced by marl 

and clay; this may be seen at Worbarrow Tout, where the great reduction in 

their thickness is not wholly due to the general westerly attenuation. 

The stone mines lie entirely east of Kingston, and are thickest in the 

district between W T orth, Langton and Durlston, where the downs are almost 

covered with tip-heaps and depressions. Many of the mines are still worked 

by the ancient methods, an inclined shaft following the chosen rock-band 

underground, the dip being generally steep. 

The stone is a more or less shelly, pale limestone, occurring in rather thin 

beds separated by shale partings with Cypridea punctata. The highest 4! ft. 

at Durlston, called the White Roach, and by Forbes the Pecten Bed, contains 

a marine fauna, including 4 Pecten', Ostrea, Gervillia obtusa Roem., Corbida 

spp. and Protocardia. The same assemblage (less the unidentified 4 Pecten') is 

met with at several horizons, separated by beds in which only freshwater or 

estuarine forms are found—Viviparus, Limncea, Hydrobia chopardi de Lor., 

Valvata helicoides Forbes, &c. 3 

Of the greatest importance, however, is the vertebrate fauna of the Building 

Stones, which is large and varied, and has provided science with a number 

of unique forms of fishes, turtles and crocodilians. Even on a casual visit to 

1 See A. Strahan, 1898, loc. cit., p. 91. 

2 W. Koert, 1898, Inaugural-Dissertation, Gottingen, pp. 52-3. 

3 Koert, 1898, loc. cit., pp. 52-3, gives a list of mollusca from the Middle Purbeck of 

Swanage which he says are preserved in Gottingen Museum and are identical with forms from 

North-West Germany.


a mine it is usually possible to obtain from the quarrymen fin-spines of 

sharks ('ichthyodorulites') or bones or plates of the curious turtle, Pleurosternum, 

intermediate in structure between the later Cryptodira and Pleurodira, 

and so relegated to a separate sub-order, the Amphichelydia. The rich fish 

fauna of the Purbeck Beds, which has been monographed by Sir Arthur 

Smith Woodward, 1 comes almost entirely from the Upper and Lower 

Building Stones; the list is now as follows (compiled from his monograph): 

Hybodus strictus Ag. 

Asteracanthus verrucosus Eg. 

A. semiverrucosus Eg. 

Undina purbeckensis Smith Woodw. 

Lepidotus minor Ag. 

L. notopterus Ag. 

Mesodon daviesi Smith Woodw. 

Eomesodon depressus Smith Woodw. 

Microdon radiatus Ag. 

Ccelodus Icevidens Smith Woodw. 

C. arcuatus Smith Woodw. 

Ophiopsis dorsalis Ag. 

CINDER BED, 4 ft.—8 ft. 6 in. 

Histionotus angularis Eg. 

Caturus purbeckensis Smith Woodw. 

C. tenuidens Smith Woodw. 

Amiopsis austeni (Eg.) 

Aspidorhynchus fischeri Eg. 

Pholidophorus ornatus Ag. 

P. granulatus Eg. 

P. purbeckensis Davies 

Pleuropholis crassicauda Eg. 

P. longicauda Eg. 

Pachythrissops Icevis Smith Woodw. 

Thrissops molossus Smith Woodw. 

The Cinder Bed derives its name from its black scoriaceous appearance 

where weathered on the shore. It is the most conspicuous and the most 

constant bed in the whole Purbeck Series and marks a marine invasion of 

widespread importance. The mass of the rock is made up of the compacted 

shells of Ostrea distorta Sow., but in addition there are occasionally found 

other marine forms, such as Trigonia, Isognomon, Protocardia purbeckensis (de 

Loriol) Serpula coacervata Blumb., and above all the significant echinoid, 

Hemicidaris purbeckensis Forbes. 2 Unlike the oyster-banks in the Portland 

Series, with their restricted distribution, this bed is found on the same 

horizon all along the outcrop as far west as Portisham, and even in the Vale 

of Wardour. The marine episode to which it bears witness seems also to be 

marked by the presence of the same molluscan assemblage in the Weald. 

Cypridea granulosa var. fasciculata is recorded in the Cinder Bed by Jones. 

LOWER BUILDING STONES, 5 ft. 9 in-34 ft. 3 

The fauna of the Lower Building Stones is mainly freshwater. The top 

course (2 ft. 2 in. thick) immediately below the Cinder Bed is known to the 

quarrymen as the Feather Bed. From it was obtained the first jaw (the typespecimen) 

of the mammal Trioracodon major (Owen) and another jaw of 

T. ferox (Owen) came from immediately below. 4 

Sixteen feet below the top of the Feather Bed is a conspicuous 3 ft. band of 

white limestone with nodules of black chert. From this band Bristow recorded 

Viviparusy Valvata, Physa, Planorbis and Neomiodon. 

From the chert vein to the Mammal Bed at the base of the Middle Purbeck, 

1 1916-19, Pal. Soc. 

2 Usually rare, but Prof. Hawkins found 35 tests at Durlston: Q.J.G.S., vol. Ixxxi, p. cxxviii. 

3 Bristow's measurement, quoted by Woodward (1895, p. 244), was 43 ft., but according to 

Strahan's figures it is only 34 ft. (1898, p. 94). 

4 Teste Simpson. It should be noted, however, that Owen sometimes referred to the 

Mammal Bed as the Feather Bed.


shales predominate. Mr. F. W. Anderson has recently made a microscopic 

study of this part of the sequence and has discovered three rhythmic or phasal 

changes in the salt-content of the shales and in the Ostracod fauna. He 

attributes these changes to the periodic influx of fresh water into basins which 

were otherwise becoming steadily more saline. 

'The increase in salinity had a marked influence on the Ostracod fauna. The 

fresh-water deposits at the commencement of each phase contain Darwimda leguminella 

(Forbes) and Cyprione bristovii (Jones); these are followed by an early form 

of Cypridea dunkcri (Jones) and Cypridea punctata (Forbes), which are later in 

the phase replaced by Cypridea granulosa (Sow.), these latter becoming more 

abundant as the water became more brackish.' 

The third phase, according to Mr. Anderson, was terminated by the marine 

invasion marked by the Cinder Bed. 1 

MAMMAL BED, O-I ft. 

The bed chosen as the base of the Middle Purbeck division is a brown or 

grey-brown, carbonaceous, earthy layer or 'dirt bed', suggesting an ancient 

soil, and filling inequalities in the hard marl below. The wonderful vertebrate 

fauna obtained from this bed in the nineteenth century has made Durlston 

Bay world-famous. Except for the few mammalian remains found in the 

Stonesfield Slate and the Rhaetic Beds, the fauna is unique in Europe; it 

correlates, however, with an assemblage entombed in somewhat similar beds 

in the Morrison formation of North America. Most of the Purbeck specimens 

were found in a special excavation known as Beckles's Mammal Pit, near the 

top of the cliff a short distance north of Belle Vue restaurant. An exceptionally 

rich pocket was struck, for a large excavation made subsequently led to the 

discovery of only a single additional specimen. Beckles's collection, described 

by Owen, was purchased by the British Museum, where it can now be seen. 

The revision completed in 1928 by G. G. Simpson 2 has made it clear that 

the time-honoured belief that these early mammals belonged to the marsupials 

has no foundation in fact. Simpson ranges them in four orders, Multituberculata, 

Triconodonta, Symmetrodonia and Pantotheria, and he regards these as 

derived independently from the Cynodont reptiles. The last two orders may, 

he thinks, have diverged from the same stock as all the living mammals, but 

they branched off long before the marsupials and the placentals became 

differentiated. 

Since this bed is to the vertebrate palaeontologist perhaps the most important 

in the Jurassic System, it may be useful to give the complete list of 

the mammals found in it, as revised by Simpson—in all 19 species. 

LIST OF MAMMALIA FROM THE MAMMAL BED OF DURLSTON BAY 

MULTITUBERCULATA; PLAGIAULACOIDEA. TRICONODONTA; TRICONODONTID.Ê. 

Plagiaulax becklesii Falconer. Triconodon mordax Owen. 

Ctenacndon minor (Falconer). Trioracodon ferox (Owen). 

C. falconeri (Owen). T. ozceni Simpson. 

Bolodon crassidens Owen. T. major (Owen). 

B. osborni Simpson. 

B. elongatus Simpson. 

1 F. W. Anderson, 1932, Rept. Brit. Assoc. for 1931, p. 380. 

2 G. G. Simpson, 1928, Cat. Mesozoic Mammalia Brit. Mus.

SYMMETRODONTA ; SPALACOTHERIID^. 

Spalacotherium tricuspidens Owen. 

Per ales tes longirostris Owen. 

PANTOTHERIA; PAURODONTID/E. 

Peramus tenuirostris Owen. 

PURBECK BEDS: MAMMAL BED 527 

DICROCYNODONTID;E. 

Peraiocynodon inexpectatus Simpson. 

PANTOTHERIA (contd.) 

DRYOLESTID/E. 

Amblotherium pusillum (Owen). 

A. nanum (Owen). 

Kurtodon pusillus Osborn. 

Peraspalax talpoides Owen. 

Phascolestes mustelula (Owen). 

Only second in interest to the mammals are the unique dwarf crocodiles found 

in this bed and at some other horizons. Most of them were described by Owen, 

and they have been more recently revised by Sir Arthur Smith Woodward. 1 

The Teleosauridae are represented by the genus Petrosuchus; but the majority 

belong to the Goniopholidae, a family much more akin to the marsh-loving 

forms of the present day. The genus Goniopholis is full-sized; the rest, Nannosuchus, 

Theriasuchus and Ozceniasuchus, are dwarfed. 

Zone of Cypris purbeckensis and Candona ansata: Lower Purbeck, 93^- 

170 ft. 

MARLS WITH GYPSUM AND INSECT BEDS, 87-135 ft. 

The thick marls and clays forming the greater part of the Lower Purbeck 

Beds contain irregular masses of gypsum, some so large that they were formerly 

worked in the cliff of Durlston Bay for making Plaster of Paris. In the 

upper part there are also pseudomorphs in mud of crystals of rock-salt, the 

cavities filled with carbonate of lime, and other salts also have been detected: 

the deposits seem to have formed in muddy evaporating basins or salterns. 

Mollusca are rare, but insects were apparently blown or washed into the water 

in abundance. Two levels of insect-beds were recognized by Fisher and 

Bristow, who divided the series into six subdivisions, but the details are so 

inconstant that they are not worth noting; Bristow's sequence (quoted by 

H. B. Woodward) does not tally with Fisher's and was not adopted by 

Strahan. The insects include butterflies, beetles, dragon flies, locusts, grasshoppers, 

ants and aphides, an assemblage indicative of a temperate climate. 

Ostracods are, as usual, abundant at certain levels, but the species are not 

th? same as those found in the higher divisions; the most characteristic are 

Cc ndona ansata Jones, Candona bononiensis Jones and Cypris purbeckensis 

Forbes. The marine bivalve Protocardia purbeckensis is not uncommon but 

badly preserved, and gave rise to the somewhat inappropriate name Cockle 

Beds for the bulk of the Lower Purbecks. Occasionally Neomiodon, Planorbis, 

Corbula, &c. may be found, and also the Isopod, Archceoniscus brodiei. At the 

base are numerous bands of freestone interbedded with the marls and shales to a 

thickness of 36 ft. in Durlston Bay and 22 ft. at Lulworth. Bristow called this 

basal portion the Cypris Freestone, from the occurrence of Cypris purbeckensis. 

BROKEN BEDS, IO-I5 ft. 

Towards the base of the Lower Purbeck Beds limestones predominate, the 

lowest of all, the Caps, simulating at a distance the Portland Stone. Above 

the Caps all over Purbeck (perhaps the best section being at the Fossil Forest, 

1 A. Smith Woodward, 1886, P.G.A., vol. ix, pp. 318-26.


near Lulworth) are remarkable shattered limestones known as the Broken 

Beds, the formation of which has given rise to a controversy of long standing. 

They consist of fragments of limestone set at all angles in an earthy rubble, 

like a crush-breccia. The Rev. O. Fisher first suggested in 1854 1 that the 

brecciation might be due to the sediments having been deposited over a mass 

of vegetation, which subsequently decayed and allowed the covering rock to 

fall in. But H. B. Woodward considered that the fact that the disturbance 

affects higher beds in some places than in others proved the shattering to have 

been subsequent to Purbeck times. He believed that the Broken Beds represent 

a gigantic slide-plane, upon which the whole of the Purbeck Beds above 

have been moved forward by pressures set up during the formation of the 

Purbeck Anticline and the Thrust Fault. 2 Sir A. Strahan, however, reverted 

to Fisher's view. He pointed out that the Broken Beds follow approximately 

the same stratigraphical horizon, not only from Durlston Head to the Isle of 

Portland, but also in the Vale of Wardour, and that they everywhere overlie 

a forest-grown land surface; moreover, that the nearest approach to the 

Broken Beds in other formations is a brecciated clay found above the Cromer 

Forest Bed. 3 

CAPS AND DIRT BEDS, with FOSSIL FOREST, 9-I9 ft. 

The junction with the Portland Stone is obscured by faulting at the south 

end of the Durlston Bay section, in Durlston Head, but numerous exposures 

of the junction and the basal Purbeck Caps are to be seen in the quarries along 

the cliffs westward to St. Alban's Head. The finest sections of all are at the 

Fossil Forest near Lulworth, and in Pondfield Cove, Worbarrow. Everywhere 

the junction of the two formations, though sharply defined, is perfectly 

conformable. 

THE CAPS consist of two bands, a Soft Cap above (4^-7\ ft.) and a Hard Cap 

below (4I-11 ft.), with thin impersistent fossil soils and limestone gravel, 

called DIRT BEDS, at the base of either or both. The stone composing the 

Caps is a peculiar, porous, tufaceous and botryoidal limestone, occasionally 

enclosing such mixed fossils as fish-remains, Viviparus, Ostracods and 

Archceoniscus. 

The section of these beds at the Fossil Forest, midway between Bacon Hole 

and Lulworth, is a highly instructive and vivid sight. The cliff there rises 

to a height of about 100 ft. above the sea, and the lower part, formed by 

the Portland Stone, is vertical or even overhanging; but the upper part, 

formed by the softer Purbecks, is weathered back in a gentler slope down 

which it is easy to scramble. Midway down, the Caps form a broad ledge 

upon which the famous 'forest' is displayed (PL XXVII). 

By looking over the edge of the ledge it is possible to see that the Hard Cap, 

which is very thick, rests directly on the Portland Stone with the usual sharp 

but conformable junction. Between the Caps is the principal Dirt Bed of 

this part of the district, a seam of black earth 6-18 in. thick, so full of pebbles 

of limestone that it resembles a gravel. The Soft Cap above, 2-4 ft. thick, here 

also a hard tufaceous limestone, encloses the silicified trees, and the standing 

1 O. Fisher, 1856, Trans. Cambr. Phil. Soc., vol. ix, p. 566. 


3 A. Strahan, 1898, loc. cit., pp. 80-2.

PLATE XXVII 


Bacon Hole and the Mupe Rocks, looking across to Worbarrow Bay 

and Gad Cliff. 

Rocks of Portland Stone and cliff of Purbeck Beds, tilted in the Purbeck 

Anticline. Chalk cliffs of Arish Mell behind on left. 


The Fossil Forest, Lulworth. 

Silicified boles of conifers encased in 'burrs' of tufa, in position of growth in the 

dirt bed, basal Purbeck Beds.

PLATE XXVIII 


Durdle Door, near Lulworth. 

The arch is of Portland Stone and the highest part of the promontory is of 

Purbeck Beds. The soft Wealden Beds form the neck as far as the conspicuous 

band of dark Gault Clay, in front of which is the Chalk. 


Vertical Purbeck Beds, Durdle Cove, Lulworth. 

The whole Purbeck formation is seen, with the Wealden Beds on left, all 

greatly reduced in thickness (partly by squeezing out of the clays).

PURBECK BEDS: ISLE OF PORTLAND 529 

stumps, enveloped in tufa, protrude on the upper surface as huge round 

bosses (called 'burrs'), their centres sometimes hollowed out to form cupshaped 

depressions. Beside them lie the prostrate trunks, broken off once 

close to the root and again some 8-10 ft. higher up, and likewise enclosed 

in sheaths of tufa, although the trees within are silicified. 

FIG. 88. The Great Dirt Bed of the Isle of Portland, showing 

boles of trees with roots, cycads, and pebbles of Portland 

Limestone. The Dirt Bed rests on the tufaceous Top Cap 

limestone and is overlain by the Aish. (After Buckland and 

De la Beche, 1836, Trans. Geol. Soc. [2], vol. iv, p. 13.) 

(b) The Isle of Portland 

Only Lower Purbeck Beds remain on the Isle of Portland. The greatest 

thickness survives north and west of Southwell, where little less than 100 ft. 

are exposed in the cliff. An old geological map by Buckland and De la Beche 1 

shows that a century ago Purbeck Beds also overspread much of the northern 

part of the island, whence they have since been completely quarried away. 

The essential features of the basement-beds, the tufaceous Caps with 

silicified trees and Dirt Beds, are present, but the details differ considerably 

in adjoining parts of the island and there is nowhere an exact replica of the 

development on the mainland. Little is to be gained by following out the 

changes of detail, and a typical section will suffice to illustrate the succession 

(fig. 89, p. 530). 

The bulk of the beds consists of marls with bands of white fissile limestone, 

up to 3 ft. thick but splitting into thin laminae; these bands are called by the 

quarrymen 'Slatt' (slate). The chief interest, however, is centred in the basement-beds. 

Below the lowest slatt is a hard streaky limestone with layers of 

sand, graphically called the Bacon Tier (about 2 ft.), below which, and often 

joined on to it, is another 2 ft. band of soft argillaceous limestone called the 

Aish. This rests on a tufaceous limestone called the Burr Bed or Soft Burr, 

which probably corresponds with the Soft Cap of Purbeck. It contains 

silicified tree-stumps and trunks enveloped in tufa (the 'burrs' of the quarrymen) 

; Woodward records that one was found so large that people came from 

1 Trans. Geol. Soc. [2], vol. iv, pi. 1.


far and wide to view the 'fossil elephant'. The Soft Burr rests on the Upper 

or Great Dirt Bed, a blackish layer in places up to i ft. thick, with rolled 

limestone pebbles and well-preserved silicified trees and Cycadeoidce. The 

trees are much more perfectly preserved than in Purbeck, some having been 

obtained as much as 23 ft. in length 

and from 2 to 4 ft. in diameter (see 

MARL 

5LATT 

MARL 

5LATT 

MARL 

BACON TIER 

AI S H 

SOFT BURR 

GREAT DIRT 

BED 

LOWER DI RT 

BED 

FIG. 89. Section of the basement-beds 

of the Lower Purbeck in the quarries at 

the south end of the West Weare Cliff, 

north of Black Nore, Isle of Portland. 

fig. 90 and PI. XXVI). At the base are 

two massive blocks of tufaceous limestone 

called the Top Cap (10 ft.) and 

the Skull Cap (2-3 ft.), easily mistaken 

at first sight for Portland Stone. Between 

them, however, is in places an 

impersistent Dirt Bed, thinner than 

that above, and in the Top Cap may 

be seen many hollow casts of treetrunks. 

The lower Dirt Bed has 

yielded some of the best specimens 

of Cycads known. 

At the south end of the island the 

Top Cap, Upper Dirt Bed and Soft 

Burr are not represented. 

The basement-beds of the Purbeck 

rest everywhere upon the Roach of 

the Portland Stone and the junction 

is perfectly even and conformable. 

Nevertheless, some of the pebbles in 

the Dirt Bed have been identified as 

derived from the Portland Stone, 1 

thus proving that there was erosion 

somewhere in the vicinity, possibly 

over the crest of the Weymouth 

Anticline. 

(c) The Northern Limb of the Weymouth 

Anticline from Ringstead 

to Portisham, and the Chaldon 

Anticline. 

The Purbeck Beds follow the Portland 

feature along the outcrop in the 

northern limb of the Weymouth Anticline 

and round the Poxwell Circus, 

but there are now only small sections. About 12 ft. of the Lower Division is 

also seen in the faulted block below Holworth House, in Ringstead Bay. The 

details again differ from those noted elsewhere. 

A complete section (total thickness 190 ft.) was formerly seen in the 

railway-cutting near the entrance to the Bincombe Tunnel, 2 and buildingstones 

in the Lower Purbeck, on the horizon of the Cypris Freestone, are still 

1 H. B. Woodward, 1895, J.R.B., p. 26s. 

2 Described by C. H. Weston, 1852, Q.J.G.S., vol. viii, p. 116.

PURBECK BEDS: BINCOMBE TUNNEL 531 

from time to time quarried near by, 

close to Upway. These exposures were 

studied in great detail by the Rev. O. 

Fisher, who described Upper and Lower 

Insect Beds and obtained many specimens 

from them, and also noted the 

chert-beds in the same position as at 

Durlston, and the Cinder Bed. 1 The 

Lower Purbeck has yielded two fish not 

known at Swanage—Ophiopsis penicillata 

Ag. and Amiopsis damoni (Eg.). 2 It is 

interesting to notice that the Upper Purbeck 

Beds here were said to be coarser 

and sandier than in the Isle of Purbeck 

and to contain a larger proportion of the 

spoils of the land, such as lignite and 

plants. This evidence agrees with that 

provided by the Portland Sand in pointing 

to a land-area in the west. 

II. THE VALE OF WARDOUR 

In the Vale of Wardour a considerable 

area of Purbeck Beds occupies the surface 

on the east of the Portlandian outcrop 

about Tisbury and surrounds the inlier 

in the Chilmark Ravine (see map, p. 500). 

The total maximum thickness is not 

accurately known, but it was estimated 

by Woodward to be about 85 ft., and, by 

Andrews and Jukes-Browne, no ft. 

The general aspect of the beds and the 

fossils are the same as on the Dorset 

coast, and all three divisions have been 

recognized by their Ostracod faunas. The 

Middle Division bears witness, as in 

Dorset, to an important marine invasion, 

in which the Cinder Bed was formed, 

composed of Ostrea distorta and its 

associated marine molluscs and Hemicidarid. 

Numerous sections, especially of the 

Lower Division, have been described in 

detail by Fitton, the Rev. P. B. Brodie, 

the Rev. O. Fisher, the Rev. J. F. Blake, 

the Rev. W. R. Andrews, A. J. Jukes- 

Browne, W. H. Hudleston, and H. B. 

Woodward. To Messrs. Andrews and 

1 O. Fisher, 1856, loc. cit. 

2 A. Smith Woodward, 1916-19, loc. cit. 

rO 

u 

 

« N 

« GQ 

6 0 ^ 

? 

!re> 

II 

0 ~ 

Oh Ô 

m 


Jukes-Browne, however, belongs the credit for deciphering the Ostracod 

succession and thus establishing the correlation of the beds on a palaeontological 

basis. They were able to show, by careful collecting in situ, that the attenuated 

Purbeck Beds of the Vale of Wardour contain representatives of all the three 

divisions of Dorset, and at the same time to set bounds to the divisions. It 

was thus established that the feeble representation of the formation in the 

Vale was not due to removal of the major portion of the beds by pre-Cretaceous 

denudation, but to a piecemeal thinning out of its component parts. 

SUMMARY OF THE PURBECK BEDS OF THE VALE OF WARDOUR 1 

Zone of Cypridea punctata and C. ventrosa: Upper Purbeck, 20 ft. 

Only one good section of the Upper Purbeck Beds has been described, a 

complete one in the railway-cuttings west of Dinton Railway Station, first 

studied by Messrs. Andrews and Jukes-Browne, and later by H. B. Woodward 

in company with Sir A. Strahan. There was some difference of opinion 

regarding the horizon at which the boundary between the Wealden and the 

Purbeck Beds should be drawn, and in spite of the opinion of the earlier authors 

that there were signs of discordance between the two formations, H. B. Woodward 

and Sir A. Strahan showed that the passage was in reality perfectly 

conformable. At the same time they assigned to the base of the Wealden some 

considerable thickness of white clays and sands regarded by the earlier writers 

as part of the Purbeck. 

The Upper Purbeck Beds at Dinton as so restricted comprise 20 ft. of 

highly variable strata, ranging from blue clay and white or blue marl to brown 

sandstone and blue-hearted shelly limestone—all types of rock common in the 

same division in Dorset. Woodward regarded the highest 'lithological Purbeck' 

bed, a band of stiff white marl, as the top of the formation. At the base 

were about 6 ft. of blue clay. Messrs. Andrews and Jukes-Browne collected 

Cypridea pimctata from three levels and at one horizon they also obtained 

Cyprione bristovii. About the middle of the division Unio, Neomiodon and 

Viviparus were collected from a shelly limestone which they considered to be 

probably equivalent to the Unio Beds of Durlston Bay. 

Subzone of Cypridea granulosa and Metacypris forbesii: Middle Purbeck, 

22 ft. 2 (20-5 ft.). 

The Middle Purbeck Beds also were completely exposed in the Dinton 

railway-cuttings, as well as in several quarries, especially at Teffont Evias, 

described by Andrews and Jukes-Browne. 

The topmost bed grouped with this division was a band of hard white marl, 

its upper surface eroded and the hollows filled w r ith clay. Below this were 

about 6 ft. of shales and sandstones with occasional Neomiodon, and then 

a remarkable 3-in. layer of hard marly limestone in places crowded with the 

Isopod Archceoniscus brodiei. 

About 2 ft. below the Archceoniscus Bed is the most easily recognized 

horizon of all, the Cinder Bed, 1 ft. 3 in. thick at Dinton, 2 ft. 6 in. thick at 

1 W. R. Andrews and A. J. Jukes-Browne, 1894, Q.J.G.S., vol. 1, pp. 44-69; H. B. Woodward, 

1895,7.^.!?., pp. 267-75. 

2 Woodward's estimate plus a portion of his Lower Purbeck which contains Ostracods 

belonging to the Middle Division. Andrews and Jukes-Browne estimated at least 32 ft.

PURBECK BEDS: VALE OF WARDOUR 533 

Teffont Evias railway-cutting, and 1 ft. 6 in. thick at Teffont quarry (near the 

church); as in Dorset, this bed is largely made up of Ostrea distorta Sow. 

Although it would usually be rash to consider oyster-beds contemporaneous 

at places so distant as the Vale of Wardour and the Dorset coast, the correlation 

in this instance is supported by several other marine forms—occasional 

spines of Hemicidaris purbeckensis and two species of Trigonia, one likened 

to the Portlandian T. gibbosa Sow., the other a new species, T. densinoda 

Etheridge. 

Below the Cinder Bed are more alternations of compact marlstone, shelly 

limestone and shale, for the most part indistinguishable lithologically from 

the local Lower Purbecks. The best section of these beds w r as described by 

Andrews and Jukes-Browne in the large quarry west of Teffont Evias Church. 

Here they found, by carefully collecting the Ostracoda in situ, that Cypridea 

punctata extended to 7 ft. 10 in. and C. granulosa var.fasciculata to 11 ft. below 

the Cinder Bed, while at lower levels only Cypris purbeckensis was found; they 

therefore drew the line between the Middle and Lower Purbecks 11 ft. below 

the Cinder Bed. In the lowest bed of their Middle Purbeck Cypris purbeckensis 

and Cypridea granulosa both occurred plentifully, but they justifiably 

selected 'the point where Cypridea fascicidata first makes its appearance'. 

'It is true', they wrote, 'that Cypris purbeckensis is still the most abundant 

form, so that the bed might be grouped w T ith either division, but we prefer to 

regard the incoming of Cypridea fasciculata as marking the base of the Middle 

Purbeck Beds.' 1 

Although this careful work showed that the classification of the Purbeck 

Beds by means of the Ostracods could be applied in the Vale of Wardour as 

well as in Dorset, H. B. Woodward remained unconvinced of the zonal value 

of Ostracods, and having declared his scepticism in the discussion following 

the reading of Andrews's and Jukes-Browne's paper, he ignored their results 

when compiling The Jurassic Rocks of Britain. In describing the Teffont 

Evias quarry he was guided by the lithology, and in order to group all the 

main bands of limestone together, he carried the top of the Lower Purbeck 

up to within 4 ft. 7 in. of the Cinder Bed (and to within 1 ft. 5 in. of it in the 

Dinton railway-cutting). At the same time, Andrews's and Jukes-Browne's 

records of Ostracods appear in his account merely as 'Cyprides'. 2 

Zone of Cypris purbeckensis and Candona ansata: Lower Purbeck, 

about 45 ft. 3 

The Lower Purbeck Beds have been exposed in numerous quarries. The 

highest portions, best seen in the base of the quarry south-west of Teffont 

Evias Church, contain white limestone bands locally known as Lias and bearing 

a resemblance to true Lower Lias limestones. Lithologically they are 

indistinguishable from the basal portion of the Middle Purbeck, but they may 

be recognized by the characteristic Cypris purbeckensis. Fish-remains also are 

numerous, some as fine as any obtained in Dorset in the Middle Division. 

From the Lower or Middle Purbeck of Teffont came the types of Coccolepis 

1 R. W. Andrews and A. J. Jukes-Browne, 1894, loc. cit., p. 54. 

2 1895,7.^.^., pp. 271,274. 

3 Woodward's estimate, less that portion of his Lower Purbeck which is here assigned to 

the Middle Division. See, however, Andrews and Jukes-Browne, 1894, P- 63, who estimate the 

thickness of the division to be 70 ft.


andrewsi Smith Woodw., Mesodon parvus Smith Woodw., Pholidophorus purbeckensis 

Davies and Pleuropholis formosa Smith Woodw.; while from the 

Vale of Wardour, but less localized, came the types of Ophiopsis breviceps 

Egerton (a common species), Enchelyolepis andrewsi Smith Woodw., Ceramurus 

macrocephalus Egerton and Leptolepis brodiei Agassiz. 1 

The basement-beds have been described in the Chilmark Ravine and at 

Chicksgrove, Wockley and other places near Tisbury, the details differing in 

every exposure; on the whole, however, they are strikingly like their counterparts 

in Dorset. At Chilmark the base is formed by a 6 ft. block of tufaceous 

'cap' with seams of chert, and a little higher up there are two Dirt Beds with 

gravelly stones, fossil wood and Cycadeoidea. In the basal bed at Wockley 

Messrs. Andrews and Jukes-Browne found the characteristic Ostracods Candona 

ansata and C. bononiensis, but as these were supposed to be estuarine 

forms, they were led to include the bed with the Portland Stone. Woodward, 

however, maintained that it unquestionably belonged to the Purbeck and that 

there was nowhere in the Vale of Wardour any difficulty in determining the 

junction between the two formations. Subsequent work on the Ostracods has 

brought the palaeontology into line with Woodward's opinion, for Candona 

ansata and C. bononiensis have now been listed as definitely freshwater forms. 2 

Hudleston considered, from the way in which the Purbeck Beds rest upon 

different subdivisions of the Portland Stone, that there is undoubtedly an 

unconformity between the two. 3 But this view was contested by Woodward. 4 

'No doubt', he wrote, 'there are abrupt changes here and there between the formations, 

as there sometimes are between individual beds in the Portland series. 

There is, however, no discordance such as would imply upheaval and denudation of 

the strata. The phenomena may be attributed in part to contemporaneous erosion, 

in part to the attenuation and local deposition of certain [Portlandian] sediments; 

while again the variations in the lithological characters of different layers serve to 

render the results of minute correlation very difficult and uncertain.' 

III. THE SWINDON OUTLIER 

A small patch of both zones of the Purbeck Beds, with a maximum thickness 

of 19 or 20 ft., caps the Portlandian outlier on Swindon hill. The only 

exposure described is the old Town Gardens Quarry, but the condition of the 

section is now so bad that we have to rely almost entirely on the published 

accounts of the last century. 

The beds comprise a varied series of marls, clays and hard white marly 

limestone, from which Viviparus, Unio, Planorbis and the Ostracods Candona 

ansata, C. bononiensis, Cypris purbeckensis, Cypridea dunkeri, C. punctata and 

Cythere retirugata have been recorded. But of any Dirt Beds or tufaceous 

limestones suggestive of the Caps farther south, there is no sign. 

At Swindon there is no doubt about the relations of the Purbeck to the 

Portland Beds: they are distinctly unconformable. The uneven base of 

the Purbecks was seen in the west face of the quarry to cut down across the 

Titanites zone or Creamy Limestones on to the Swindon Sand and Stone 

1 A. Smith Woodward, 1916-19, op. cit. 

2 F. Chapman, 1899, P.G.A., vol. xvi, p. 43. 

3 W. H. Hudleston, 1883, P.G.A., vol. vii, pp. 170-4. 

4 H. B. Woodward, 1895, ^.tf.B., p. 208.

PORTLAND B E D S : OXFORD AND AYLESBURY AREA 

(Kerberites zone), and in the base of the Purbeck both Blake and Woodward 

found derived blocks of Swindon Stone and pebbles of Creamy Limestone 

containing Aptyxiella portlandica. To Woodward it appeared also that there 

was a certain amount of overlap of the lower layers of the Purbeck Beds by the 

higher. 1 

Blake somehow became obsessed with a belief that the beds here were older 

than those farther south, and were to be correlated with a part of the Portland 

Beds of Dorset. 2 But Woodward remarked 'such a view seems to me purely 

hypothetical'. 3 It would seem more probable, if the overlap suggested by 

Woodward be a fact, that the beds seen at Swindon are not even so old as the 

lowest Purbeck Beds in the type-locality. In this way might be explained the 

absence of tufaceous Caps or Dirt Beds and the unconformity. The records of 

Cypridea punctata and C. dunkeri point to the presence of Middle or Upper 

as well as Lower Purbeck Beds. Although the summit is not seen at Swindon, 

these Ostracods give an indication of great attenuation in the formation 

between South and North Wiltshire. 

IV. THE OXON.-BUCKS. AREA 

No Purbeck Beds are known on the Portlandian outlier at Bourton, but in 

the large tract in Bucks, and on the borders of Oxford they are scattered over 

almost as wide an area as the Portland Beds. They are reduced to a number 

of small outliers capping hills of Portland Stone and inliers showing through 

the Gault, or to small outcrops protruding from beneath Lower Cretaceous 

sands. At the best these are merely fragments, left over by the accidents of 

denudations, not only of the subaerial denudation of the recent period which 

has dissected the country into scattered hills, but also of three subaqueous 

denudations in Lower and Upper Cretaceous times. As explained in the last 

chapter, the Portland sequence is not everywhere complete, owing to the 

overstep of the Cretaceous rocks, and from this it follows that in places the 

Purbeck Beds were either entirely removed or never deposited. 

In the ridge of Shotover Hill, near Oxford, a small patch of Purbeck Beds 

occurs at the south end, about Garsington, but towards the north the Lower 

Cretaceous sands rest on the Kerberites zone of the Portland Stone. This is 

of especial interest because the sands, called the Shotover Sands or Shotover 

Ironsands, have from time to time yielded freshwater fossils (of which a collection 

is preserved in the Oxford University Museum) denoting that they are 

of Wealden date. They seem to be overlapped or overstepped in turn by the 

marine Lower Greensand. Lamplugh investigated the age of the Shotover 

Sands (including those of Brill); and after revising the stratigraphy of the 

district of their occurrence and summarizing the palaeontological evidence, 

he agreed with the opinion reached by Strickland, and later by Phillips and by 

Prestwich, that they are entirely of freshwater origin and that 'they represent 

the lowermost part of the Wealden Series of Kent and Sussex, and may be 

correlated with the Hastings Beds'. 4 

Thus there is in the Oxford district the first unequivocal evidence of overlap 

1 J. F. Blake, 1880, Q.J.G.S., 

p. 277. 

vol. xxxvi, pp. 203, 207; H. B. Woodward, 1895, J.R.B., 

2 1880, loc. cit., pp. 203-13, and repeated in 1885, Q.J.G.S., vol. xli, p. 352. 

3 1895, J.R.B., p. 278. 

4 G. W. Lamplugh, 1908, in Pocock, 'Geol. Oxford', p. 66, Mem. Geol. Surv,


of the Purbeck by the Wealden Beds. No such overlap is apparent in the 

west; but under the north and east of Kent, where the formations approach 

nearer to the London-Ardennes landmass than at Oxford, it is proportionately 

more strongly marked. 

The relics of Purbeck Beds that survive in Oxon. and Bucks, are now only 

poorly exposed, but Fitton described numerous sections, since for the most 

part obscured. 1 A general survey of the area was published in 1899 by Prof. 

A. Morley Davies, who described most of the exposures then extant. 2 He 

enumerated eighteen patches of Purbeck Beds, at the following localities: 

Garsington, Long Crendon, Brill, Towersey, Haddenham and district, Stone, 

Bishopstone, Aylesbury, Coney Hill, Quainton Hill, Oving Hill, Weedon 

and Stewklev. Since then the part of the area around Aylesbury has been 

again covered by Mr. E. A. Merrett, who searched especially for Ostracoda 

in situ? 

The most complete sections that have been described are the well-known 

Bugle Pit at Stone (Hartwell), where 12 ft. of Purbeck Beds can still be seen, 

and a quarry west of the cross-roads (King's Cross) north of Haddenham. 

This quarry, which was described by Prof. Davies and yielded interesting 

Ostracods, showed 8 ft. of Purbeck Beds without reaching the top, but it is 

now filled up with tins. The other exposures are all considerably smaller. 

Lithologically the beds are highly variable, as in the other localities, consisting 

chiefly of green or grey clays and marls, with thin seams of hard 

whitish limestone, occasionally botryoidal or showing obscure oolitic structure. 

Some of the bands are shelly, and the genera Viviparus, Planorbis, 

Neomiodon, Modiola and Mytilus have been recorded, but nearly always too 

badly preserved for specific identification. Fish teeth and scales, too, are 

not uncommon: Pleuropholis serrata Egerton and Arthrodon intermedius 

Smith Woodw. have been collected from the Bugle Pit, Hartwell, and near 

Aylesbury. 

Of greatest importance, however, are the Ostracoda, which Messrs. 

Chapman and Merrett have turned to good account in correlating with other 

areas. Mr. Merrett's collecting in those pits which are still open, and Prof. 

Davies's in some others now closed, have established that Middle or possibly 

even Upper Purbeck Beds are present in some of the localities in the Aylesbury 

district. At the Bugle Pit near Hartwell, at Haddenham near Ford, and 

at Creslow Farm near W 7 hitchurch, they have found that the uppermost 

portion of the sequence contains only the Middle or Upper Purbeck forms 

Cypridea punctata, C. dunkeri, C. gramdosa and Cyprione bristovii, while the 

rest of the sequence is characterized by the Lower Purbeck forms Candona 

ansata, C. bononiensis, Cypris purbeckensis, Cythere transiens and C. retirugata. 

In the Bugle Pit, Mr. Merrett describes the junction of the two divisions as 

clearly visible in the form of an uneven line running through a thick bed of 

unstratified marl, from 2 ft. 10 in. to 3 ft. 3 in. below the top of the pit. He 

speaks of the relations of the two divisions, from the upper of which he 

obtained only the Middle or Upper Purbeck Ostracods, as being unconformable 

and proclaiming erosion within the Purbeck formation. At this pit and 

1 W. H. Fitton, 1836, Trans. Geol. Soc. [a], vol. iv, pp. 269-92. 

2 A. M. Davies, 1899, P.G.A., vol. xvi, pp. 15-58. 

3 E. A. Merrett, 1924, Geol. Mag., vol. lxi, pp. 233-8.

PURBECK BEDS: KENT AND SUSSEX 537 

at two other places in the district, namely Brill and the railway-cutting -]- mile 

west of Haddenham, seams of peculiar earthy breccia have been noticed, 

consisting of angular fragments of pale mudstone and bits of lignite scattered 

in a muddy loam. Similar rock was found in Kent. 1 

At some localities, such as the pit now filled in, at King's Cross, north of 

Haddenham, and again between Bishopstone and Walton, Prof. Davies 

collected from the Lower Purbeck Beds a mixture of species of different 

habitat, apparently indicating a gradual transition from marine to freshwater 

conditions, but probably only of minor and local importance, like the phases 

in the Middle Purbecks of Durlston Bay, detected by Mr. Anderson. There 

is never any difficulty in separating the Purbeck Beds from the purely marine 

Portland Stone with its highly characteristic fauna of large mollusca. The 

dividing line is as usual sharp, although there are no signs of unconformity. 

The types of basement-beds so characteristic of Dorset and the Vale of 

Wardour are generally entirely absent. Silicified wood has been noted at 

Garsington, however, and Buckland recorded traces of a dirt-bed above the 

Portland Stone about 2 miles north of Thame—probably at Long Crendon. 2 

The recent studies in the Ostracods enable us to obtain a far truer conception 

of the meaning of the Purbeck Beds of this area than was possible 

before. We may now visualize a thin formation made up of both the Lower 

and the Middle and perhaps also the Upper Divisions of Dorset, and therefore 

as truly representative of the fully developed sequence as are the greatly 

reduced but composite Portland Beds beneath. 

V. KENT AND SUSSEX 3 

The part of the trough in which the Purbeck Beds attain their greatest 

thickness in Britain is that underlying the Weald of Kent. It may be presumed 

that the underground extension is continuous from Dorset, but on this 

point there is no evidence. The beds crop out at the surface over a small area 

in the crest of the Wealden Anticline, north and north-west of Battle. The 

total length of the outcrop does not exceed 10 miles and the breadth is nowhere 

so much as 1 mile; and it is separated into three portions, of which the 

two easterly are due to faulting. 

The beds have been worked at many places on the outcrop. The general 

development is closely comparable with that in Dorset, the succession consisting 

of shales and clays with subordinate thin limestones, wrought in open 

quarries and in shafts, and the fauna comprising the familiar molluscs Viviparus, 

Unio, Corbula, Neomiodon, Melanopsis and Ostrea distorta, with insect 

remains, Purbeck Ostracods and fish and reptile bones. Conybeare and 

Phillips in 1822 and W T ebster and Fitton in 1824 recognized the similarity 

between these oldest strata exposed in the Weald and the Purbeck Beds. 

From surface indications the thickness was estimated at about 400 ft., as in 

Dorset. 

In the present century a flood of new light has been thrown on these beds 

by the borings for coal. The formation was penetrated from top to bottom 

1 G. W. Lamplugh, 1908, in Pocock, 'Geol. Oxford', p. 63 ; and 1911, 'Mesoz. Rocks in Coal 

Expl. in Kent', p. 40 (with photograph); Mems. Geol. Surv. 



1923, loc. cit.; also H. B. Woodward, 1895,7.^.5., pp. 280-6.


by five borings: one was on the south side of the Weald at Battle, near the 

outcrop but started on Wealden Beds; the others farther north, at Penshurst 

south-west of Tonbridge, and at Pluckley, Hothfield and Brabourne, in the 

Ashford district. 

The Battle site was 2§ miles east-south-east of the old sub-Wealden 

borings of 1874-5, but they had started on Purbeck Beds and therefore did 

not penetrate the full thickness. The new sinking of 1907-09 first passed 

through 424 ft. of Wealden Beds and proved the total thickness of the Purbecks 

(according to the grouping adopted by Lamplugh) to be 387 ft. The 

greatest thickness known in Britain was proved at Penshurst, the most 

westerly of the borings, where 562 ft. of strata were grouped with the Purbeck 

Beds. 

The more easterly borings showed great attenuation: at Pluckley, 23 miles 

east of Penshurst, the thickness was 100 ft., at Hothfield it was 68 ft., and 

at Brabourne only 60 ft. Finally, in the numerous borings in the country 

farther east and north, the formation was altogether absent. 

An interesting fact in connexion with this easterly and northerly attenuation 

is the overlap of the Purbeck Beds by the Wealden, already noticed at Oxford. 

In the westerly borings, those in which Purbecks were present, the boundary 

could only be fixed with difficulty and arbitrarily, owing to the perfect 

gradation from the one formation to the other. Farther east, however, the 

Wealden Beds were proved to pass on after the disappearance of the Purbecks 

and they were met with in numerous other borings, resting upon the lower 

formations. At Dover and Folkstone the Wealden Beds (themselves attenuated) 

rested upon an eroded surface of the Kimeridge Clay; at Guildford, 

Chilton, Fredville and Harmansole they had descended on to Corallian Beds; 

at Oxney on to Kellaways Beds; and at several other more remote places they 

were in contact with Great Oolite or the Palaeozoic platform. 

In the Penshurst section, where the beds were most fully developed, the 

succession consisted almost entirely of clays and shales with subordinate 

mudstones or thin sandstones, with only very occasionally minor bands of 

limestone; in the more easterly sections limestones became somewhat more 

prominent. In all the borings the palaeontological succession was much the 

same. The fauna was predominantly a freshwater one, except in a band about 

the middle, which denoted a marine invasion probably to be correlated with 

that of the Middle Purbeck Beds of Dorset and the Vale of Wardour. 

The commonest fossil in the highest 130 ft. of shales at Penshurst was 

Viviparus, recalling the Viviparus Clays and Purbeck Marble of Dorset. The 

marine invasion, with the usual Ostrea distorta, Protocardia and Isognomon, 

was detected between 268 ft. and 278 ft. from the top. The same assemblage 

occurred also about the middle of the section at Brabourne, where some more 

specific identifications were possible: Dr. Kitchin was able to recognize 

Protocardia purbeckensis (de Lor.), also an undescribed species of Protocardia 

and Corbula alata Sow. Throughout most of the rest of the succession the 

fauna was found to be essentially freshwater. In the upper part, but below 

the maximum of Viviparus, bivalves, principally Neomiodon and Unio, were 

so numerous that at intervals they formed flaggy layers of shelly limestone. 

In the Lower Division fossils were as usual rare, consisting principally of 

fish-remains and Ostracods. On the whole the use that could be made of the

PURBECK BEDS: KENT AND SUSSEX 539 

Ostracods in correlating was disappointing when compared with the results 

obtained in Buckinghamshire and abroad. However, the two zones are 

definitely recognizable from the records: Cyprispurbeckensis w T as restricted to 

the lower beds, below the marine horizon, and Cypridea punctata was recorded 

from a number of levels in the upper part of the series, the lowest 

record being 17 ft. below the marine band. Several additional Ostracods were 

found in both Upper and Lower Divisions but could not be identified. 

The lowest 200 ft. of the beds at Penshurst (and lesser thicknesses at the 

base of all the other sections) were found to be highly charged with gypsum. 

The mineral is also present at the outcrop in Sussex, where it is about 60 ft. 

thick, and it is extensively mined near Netherfield. This provides another 

link with the Purbecks of Dorset, where it will be remembered gypsum was 

formerly worked for making plaster of Paris from the Lower Purbeck Beds 

of Durlston Bay. 

The junction with the Portland Beds wherever seen in the Kent borings 

was abrupt but devoid of any signs of erosion or unconformity.

CHAPTER XVII 

THE END OF JURASSIC TIME AND THE 

CRETACEOUS BOUNDARY 

I. THE TRANSITION FROM JURASSIC TO CRETACEOUS IN THE 

BRITISH ISLES 

OVER all the northern part of the British Isles evidence bearing on the 

events in the closing phases of the Jurassic period is entirely lacking. In 

Scotland and in Northern and Central England as far south as Bedfordshire 

the record is cut off abruptly in the Kimeridge Clay, and it is unprofitable 

to speculate on what may have taken place in the interval between the deposition 

of the Kimeridge Clay and its truncation by the transgressive Lower 

Cretaceous (Neocomian and Aptian) seas. Some rolled pebbles and fossils 

incorporated in the basement-beds of the Cretaceous in this area have been 

identified with Portlandian forms and have been taken to indicate a former 

extension of Portland Beds far beyond the present outcrop; but the identifications 

have been seriously questioned, and it seems probable that all the 

species not derived from the Kimeridge Clay are Cretaceous. 1 

We will therefore abandon the north for a time and concentrate our attention 

on the tract south of Leighton Buzzard in an endeavour to trace out the 

concluding events of Jurassic time in Britain. The quest is not a new one, but 

we can embark on it equipped with a great deal more accurate information 

than was at the disposal of our predecessors. 

We now know, thanks to Buckman's researches on the ammonites, that the 

marine Upper Portland Beds of Oxfordshire and Buckinghamshire are complete, 

and that there are therefore no grounds for a supposition at one time 

entertained, that the Purbeck Beds of that area and of Swindon were laid down 

while Portland Stone was forming in Dorset. 2 Moreover, a knowledge of the 

Ostracods enables us to state that both of the zones recognizable in the Purbeck 

Beds of Dorset are present in these northerly outcrops. We must therefore 

picture the peculiar conditions of the Purbeck period, the low-lying 

swamps and lakes, now elevated into dry land, now depressed beneath the 

sea, as extending from the English Channel between East Kent and West 

Dorset at least as far inland as Swindon, Oxford, Aylesbury and Leighton 

Buzzard. A number of facts point to these most northerly existing outcrops 

having lain near the fringe of the area of deposition: the extreme thinness of 

the beds, the overlapping of successive members one over another at Swindon, 

and their local unconformity to the Portland Beds, the discordance between 

the two Purbeck zones at Hartwell, and the fact that the marine advance of 

the Middle Purbeck left no trace and so presumably did not extend so far 

north. Similarly the rapid attenuation of the Dorset Purbecks towards the 

west, commensurate with an increase in the coarseness of the sediment, points 

to permanent land not far away in that direction. In North and East Kent we 

1 G. W. Lamplugh, 1896, Q.J.G.Svol. Iii, pp. 195-8. 

2 J. F. Blake, 1880, loc. cit., and 1885, loc. cit.; and A. J. Jukes-Browne, 1892, Build. Brit. 

Isles, 2nd ed., p. 240.

SHRINKAGE OF AREA OF DEPOSITION 541 

have seen that the attenuation is even more rapid against the London- 

Ardennes landmass. 

The area from South-West Kent and Sussex to East Dorset experienced 

the maximum amount of subsidence and deposition, through the Purbeck as 

through the preceding Portland and Kimeridge periods. Here too, in the 

central region of the depression, was subsequently accumulated the greatest 

thickness (more than 2,000 ft.) of materials, still perfectly conformable with 

the Purbecks and of freshwater origin—the Wealden Formation. 

Like the Purbecks, the Wealden Beds thin out rapidly towards the east, 

west and north. Although more than 2,000 ft. thick at Swanage, they are 

reduced at Mupe Bay to 750 ft. and north of Weymouth to little more than 

350 ft.—a rate of diminution at which they would disappear when they 

reached Bridport. At the same time there is a marked westerly increase in the 

coarseness of the sediments, sands replacing clays and pebbly grits taking the 

place of sands. 

Similarly, in the Weald, although the beds in Sussex are as thick as at 

Swanage, the numerous borings in Kent have show r n that between Dover and 

Canterbury they nowhere exceed 85 ft., and beyond this, towards the northeast 

and north, soon after overlapping the Purbecks on to the Palaeozoic 

platform, they die out altogether. In the Vale of Wardour the thickness is 

much reduced, and in the most northerly outcrops of all, on the hills of 

Shotover and Brill, east of Oxford, it does not exceed 50-60 ft. 

It will thus be seen that, although the Wealden Beds are everywhere four 

or five times as thick as the Purbeck Beds, the two behave as one in regard to 

their changes of thickness and their distribution. 

The Wealden Beds are too well known to need describing in detail. In the 

region of greatest thickness, from West Kent and Sussex to East Purbeck, they 

comprise two main divisions, a predominantly sandy series below, called the 

Hastings Beds (maximum thickness about 1,000 ft.) and a predominantly 

argillaceous series above, known as the Weald Clay (maximum thickness 

1,200 ft.). At the outcrop in the Weald a number of subdivisions have been 

established; in particular the Hastings Beds are divided into Ashdown Sand 

below and Tunbridge Wells Sand above, separated by the Wadhurst Clay 

(with a maximum thickness of 180 ft.). But these subdivisions are not constant 

even at the outcrop, both of the sandy divisions being liable to replacement by 

clay (the Fairlight Clays, up to 350 ft. thick, at the base of the Ashdown Sand 

near Eastbourne, and the Grinstead Clay, up to 50 ft. thick, at any horizon in 

the Tunbridge Wells Sand). Away from the outcrop, as in the borings in 

North and East Kent and in the equally-well-developed succession at Swanage, 

the subdivisions cannot be identified, and only a broad grouping of the series 

into Weald Clay above and Hastings Beds below is possible, the details varying 

considerably from place to place. 1 

In view of this inconstancy, the lithology of the Wealden Beds can only be 

described in general terms. The coarser sediments vary from fine sand to 

coarse quartz sand with pebbly seams, and wedge-bedding is frequent, 

testifying to the action of changing currents. Some of the pebbles in the 

Weald have been identified as derived from the Palaeozoic rocks of the 

1 G. W. Lamplugh, 1911, 'Mesoz. Rocks in Coal Expl. in Kent', p. 85; and A. Strahan, 

1898, 'Geol. Purbeck and Weymouth', pp. 122-32; Mems. Geol. Surv. 

8.-)4371 P P

542 JURASSIC-CRETACEOUS BOUNDARY 

London-Ardennes landmass, but in Purbeck the quartz pebbles increase 

westward and obviously came from the west. In the Upper Wealden of 

Purbeck and the Weald have been found the first heavy minerals derived from 

the Dartmoor granite, now freshly laid bare of its thick sedimentary covering. 1 

The clays are sometimes soft and soapy, sometimes shaly and interbedded 

with lenticular and irregular limestone bands, crowded with freshwater shells 

and closely resembling some of the Purbeck Beds. Locally there are deposits 

of drift-wood, of which the classic example is the well-known Tine Raft' on 

the west coast of the Isle of Wight. 

'The character of the greater part of the formation', wrote Sir A. Strahan, 

'suggests the action of a river distributing clay, sand and gravel irregularly 

and locally on a subsiding area.' 2 The nature of the subsiding area has long 

been visualized as a great lake-basin: 'The essentially lacustrine character of 

the Wealden deposits is now generally admitted,' writes Jukes-Browne. 3 

'By some geologists they have been regarded as the delta of a great river, comparable 

to that of the Nile or the Mississippi; but as a matter of fact the deposits do 

not resemble those of a single delta, but rather those of several rivers or streams 

pouring their sediment from different directions into a large freshwater lake. This 

view was held by Searles V. Wood and by God win-Austen, and was strongly advocated 

by Meyer in 1872.' 4 

De Lapparent rightly remarks that the area drained by these rivers must 

have been far greater than all the existing mountainous regions of the British 

Isles. 

The conception of a lake filled by rivers is not radically different from the 

picture of the flat and swampy landscape in Purbeck times. All the differences 

would be accounted for by increased subsidence of the floor of the basin, 

compensated, as is usual in similar changes of level, by increased elevation of 

the surrounding land. This would set in motion the normal forces of denudation 

accompanying a cycle of activity: revival of the rivers and accelerated 

sedimentation; in fact a repetition of the processes involved in the filling up 

of the Old Red Sandstone lakes, but on a modified scale. From time to time 

in the Wealden lake, conditions locally simulated those in which the freshwater 

portions of the Purbecks were formed, as may be seen by the repetition even 

in late Wealden times of Ostracod-shales interbedded with Viviparus-limestones 

('Sussex Marble') in Sussex and Kent. 

In view of this essential continuity of conditions between the Purbeck and 

Wealden periods, it is interesting to examine more closely the junction of the 

two formations—'the convenient plane for the base of the Cretaceous' which, 

according to the most recent text-book, is 'marked by the lithological change 

from limestones and marls to sands and clays'. 5 

The best sections are undoubtedly those exposed on the coast of the Isle 

of Purbeck, especially at Worbarrow and Mupe Bays, and at Lulworth and 

Durdle Door. No one knew these sections better than Sir A. Strahan, who of 

all men might be expected to provide us with an exact level at which to draw 

so important a boundary-line. Instead, he summarized his conclusions by 

1 A. W. Groves, 1931, Q.J.G.S., vol. lxxxvii, pp. 70-2. 

2 A. Strahan, 1898, loc. cit., p. 122. 3 1911, Building Brit. Isles, 3rd ed., p. 302. 

4 1872, Q.J.G.S., vol. xxviii, p. 247. 

5 1929, Handbook to the Geol. of Gr. Britain, p. 388.

JUNCTION OF PURBECK AND WEALDEN 543 

saying that 'no line can be drawn which does not either include beds of 

Purbeck type in the Wealden or beds of Wealden type in the Purbeck, the 

two formations being absolutely inseparable'. 1 In the most favoured locality 

for studying the junction of the Jurassic and Cretaceous Systems, then, there 

is clearly no 4 convenient plane' of separation at all, and any one familiar with 

the sections knows that any line is purely arbitrary. 

In the Vale of Wardour, again, the passage is so gradual that many feet of 

argillaceous strata have been grouped with the Wealden by some authorities 

(Woodward and Strahan) 2 and with the Purbeck by others (Andrews and 

Jukes-Browne). 3 

The same difficulty was met with in the more complete of the borings in 

Kent and Sussex, where it had to be admitted that, when Purbeck and 

W T ealden Beds were both present, the position at which the boundary between 

the two should be placed was a matter of opinion. 

'At Penshurst the lowest beds [of the part of the core grouped as Wealden] were 

dark laminated shales and greenish clays with bands of ironstone and hard sandstone, 

hardly differing from the underlying Purbecks and containing the same abundance 

of fresh-water fossils. By gradual upward transition and alternation these beds 

became more sandy and less fossiliferous, containing for the most part the remains 

of plants and fish only, until in the upper 225 feet of the boring there was a predominance 

of soft yellowish sandstone, with subsidiary beds of clay.' 4 

Upon this evidence it may be considered established that in the central 

parts of the trough, where the Purbeck and Wealden Beds are most fully 

developed, the formations grade imperceptibly one into the other and form 

a perfectly continuous and conformable series. 

But, as might be expected, the earth-movements which failed to interrupt 

the essential continuity of sedimentation in the central parts of the trough 

made themselves felt at the margins, especially in the vicinity of the London- 

Ardennes landmass, a traditionally unstable region. The Kentish borings 

proved that the greatly attenuated W 7 ealden formation oversteps all the 

Jurassic formations and comes to rest on the Palaeozoic platform, before being 

in turn overstepped by the Lower Greensand. Close to the same Palaeozoic 

platform in the Boulonnais, also, it can be seen overstepping on to rocks as old 

as the Bathonian. 5 There is nothing by which to correlate these reduced 

representatives of the Wealden with the fuller sequence that is conformable 

with the Purbecks, and they may represent only the uppermost part of the 

formation. The highest beds would be expected to cover a wider area than 

the lowest and to overlap them as the result of the continued subsidence. 

This was appreciated by the authors of the Memoir on the 'Concealed Mesozoic 

Rocks in Kent', who, although they noted that even where the Wealden 

Beds are thinnest they are still argillaceous and shaly in the upper portion and 

sandy and silty in the lower, considered that these subdivisions do not truly 

represent the thick Weald Clay and Hastings Beds of the fuller sequence. 6 

Again, in the northerly outcrop on Shotover Hill, east of Oxford, the thin 

1 A. Strahan, 1898, loc. cit., p. 126. 

2 H. B. Woodward, 1895, J.R.B., pp. 267, 273. 

3 1894, Q.J.G.S., vol. 1, pp. 59-63 and 66-8. 

4 G. W. Lamplugh, in Lamplugh and Kitchin, 1911, loc. cit., p. 85. 

5 M. Parent, Ann. Soc. geol. Nord, vol. xxxii, p. 17. 

6 Lamplugh, Kitchin and Pringle, 1923, loc. cit., p. 17.


representatives of the Wealden Beds (the Shotover Sands) overlap the Purbecks 

and come to rest on the Portland Stone; but on the neighbouring Brill Hill, 

a few miles to the east, there seems to be no such overlap (fig. 91). 1 

The evidence of the palaeontology in England is entirely in favour of 

assigning the Wealden as well as the Purbeck formation to the Jurassic, and 

WEALDEN TROUGH LONDON BLOCK 

FIG. 91. Diagrammatic section across the margin of the Wealden trough of deposition, where 

the strata abut against the London landmass ; the top of the Wealden Beds restored to horizontally. 

Note that in the centre of the trough the whole series from Trias to Wealden is perfectly 

conformable but that towards the edge overlaps and oversteps develop. In particular the 

Upper Wealden overlaps the Lower, and oversteps the whole Jurassic System unconformably. 

Towards the centre of the trough, however, it is progressively difficult to distinguish overlap 

from overstep. (Relative thicknesses approximately correct, but vertical scale greatly exaggerated 

for the sake of clearness.) 

that they should be divided between the two systems seems wholly irrational 

if we consider only the English fauna and flora. 

The most recent revisers only endorse opinions arrived at before the middle 

of the last century. 

4 So far as known', writes Sir Arthur Smith Woodward in 1919, 'the fishes of the 

Wealden and Purbeck formations are essentially Jurassic, and not mingled with any 

typically Cretaceous forms. Most of them are, indeed, the specialised and evidently 

final representatives of the Jurassic families to which they belong, and very few can 

be regarded as possible ancestors of fishes which followed in Cretaceous and later 

times.' 2 

Sir Richard Owen stated the same thing of the Wealden Reptilia in 1850, 

when he brought it forward as an objection to Forbes's proposal to sever the 

Wealden from the Purbeck Beds and to place one in the Cretaceous and the 

other in the Jurassic System. Now lastly comes Dr. Simpson's verdict upon 

the Purbeck mammals, some of which have been found also in the Wealden 

Beds. He finds (1928) that they are unrelated to any Cretaceous or more 

recent stocks, but that some belong to the same orders as those represented 

in the Stonesfield Slate. 3 

Among invertebrates the testimony of the Ostracods is the most important. 

1 See above, p. 535. 

2 1919, 'Mon. Purbeck and Wealden Fishes', Pal. Sue., p. 141. 

3 1928, Cat. Mesozoic Mammals in Brit. Mus. See above, pp. 526-7.

JUNCTION OF WEALDEN AND APTIAN 545 

T. R. Jones showed that of the six species of Ostracods which he recognized 

in the Middle and Upper Purbeck Beds, five range up into the Wealden, 

where some of them become more abundant. 1 The Middle and Upper Purbecks 

are therefore much more closely linked by their Ostracod fauna to the 

Wealden than they are to the Lower Purbecks. 

The freshwater molluscs of the two formations are largely identical, but 

like all freshwater molluscan faunas, they are somewhat featureless for dating 

purposes. It has often been remarked that, taken from their context, they 

have a Tertiary or even Recent appearance. The marine mollusca (which 

occur only in the Purbecks) are all of typical Jurassic genera; but of even more 

significance than these is the Jurassic echinoid, Hemicidarispurbeckensis, found 

in the Cinder Bed, and also in the Portland Beds in the North of France. 

The plant life of the period tells the same story. The greatest authority, 

Prof. Seward, wrote in 1895, 'The evidence of palaeo-botany certainly favours 

the inclusion of the Wealden rocks in the Jurassic series.' 2 In 1931 he is still 

of the same opinion: 'Whether or not we include the Wealden series in the 

Jurassic period is a matter of secondary importance,' he writes, but, 'of greater 

importance from our point of view is the general agreement of the plants 

preserved in Wealden deposits with those of the older Jurassic floras.' 3 

In face of this consensus of opinion that the Wêalden and Purbeck Beds 

cannot be separated on palaeontological or on stratigraphical grounds, it is 

important to understand the stratigraphical relations of the Wealden Beds to 

the strata of undisputed Cretaceous date in other countries, as well as in 

England. 

So far as the South of England is concerned, the facts are once more 

abundantly clear in the coast-sections of the Isle of Wight and the Isle of 

Purbeck, especially at Atherfield in the Isle of Wight and at Punfield in 

Swanage Bay. At Atherfield the basement-bed of the marine Lower Greensand 

(the base of the Atherfield Clay) is the Perna Bed (so called from the 

occurrence of Isognomon [Perna] mulleti). It consists of 

'a brown calcareous grit, highly fossiliferous, and always contains scattered pebbles, 

some of which are rolled ammonites or other marine fossils; and it rests upon a 

slightly eroded surface of the Wealden Shales. At Punfield a highly fossiliferous 

grit, displaying the conglomeratic character of the Perna Bed, occupies a corresponding 

position at the base of the Atherfield Clay, and also rests upon a disturbed 

surface of Wealden Shales.' 4 

The Atherfield Clay yields ammonites (Parahoplitoides) which belong to an 

horizon 'well above the base of the Aptian', and the ferruginous sands 

immediately above at Punfield (formerly known as the 'Punfield Beds') have 

yielded forms of the same genus pointing to a slightly later date, but still to 

the Lower Aptian or Bedoulian. 5 

Westward through Purbeck the Lower Greensand (Aptian) oversteps 

steadily on to lower horizons in the Wealden Beds. 6 Similarly, in the exposures 

about Oxford the two formations are unconformable: the marine Aptian 

1 T. R. Jones, 1885, Q.J.G.S., vol. xii, p. 331. 

2 1895, Cat. Plants Brit. Mus., Wealden Flora, part 2, p. 240. 

3 1931, Plant Life through the Ages, p. 340. 


5 L. F. Spath, 1923, Sum. Prog. Geol. Surv. for 1922, p. 148. 

6 A. Strahan, 1898, loc. cit., p. 122.

TABLE ILLUSTRATING THE RELATIONS OF THE STRATA ON THE JURASSIC-CRETACEOUS BORDERLINE 

Ages of Neocomian and Tithonian and correlations of Neocomian after Spath, J923 and 1924 (ages of the 

Tithonian and their correspondence with the three divisions of the Purbeck rather hypothetical) 

Stages. Ages. 

{Marine Sequence) 

S. France and Jura. NW. Germany. Speeton. Lines, and Norfolk. S. England. 

APTIAN APTIAN APTIAN APTIAN APTIAN (CARSTONE) APTIAN (ATIIKKFIELD CLAY) 

BARREMIAN 

Heteroceratan "} Cement Beds (Aptian pebble-bed rests on 

r 

Wealden) 

Paracrioceratan I Zone of B. Snettisham Clay 

Hoplocrioceratan 

z 

u < 

brunsvicensis 

J (B) 

Tealby Limestone 

Tealby Clay 

HAUTERIVIAN 

Simbirskitan 

Crioceratan 

Lyticoceratan 

£ 

W < 

- s 

« O 

< 

z 

Zone of 

L B. jaculum 

1 (C) 

^ Zone of B. 

V lateris pars. 

J (D) 

(gap) 

\ Zone of B. 

f lateris pars. 

> < J 

(gap) 

U 

- z 

1 

A D 

O 

W 

s „ U 

0 

Hoplitidan 5 

g Claxby Ironstone 

. 0 < 

H 

U 

(D 

0 

S 0 

VALANGINIAN Polyptychitan 

W 

z 

^ Zone of B. 

V lateris pars. 

J (D) 

(gap) 

\ Zone of B. 

f lateris pars. 

0. 

to 

(gap) 

Hundleby Clay 

0 

w 

rt 

0 z 

Platy lenti ceratan 

(D) 

(gap) 

INFRAVALAN- 

GINIAN 

Subcraspeditan 

Spiticeratan 

Wealden 

(?) 

Coprolite Bed _ 

on Kim. Clav 

Spilsby Sandstone 

Phosphatic Pebble Bed 

on Kim. Clay 

Wealden 

J 

Io| 

H 2 

P g 

PORTLANDIAN 

Berriasellidan 

Absent or much reduced 

and inosculating with 

above. 

Kossmatian ? Middle Purbeck 

Aulacosphinctoidean 

Lower Purbeck 

Zone of 

Cypris purbeckensis 

Titanitan Marine 

Portland 

Behemothan 

(chiefly dolomites) 

Freshwater 

Limestones 

Zone of 

Cypridea punctata 

Serpulite 

Sub-Zone of 


Munder Marls 

Zone of 


Partly represented 

by the Plattenkalk 

(mainly marine) 

Upper Purbeck 

Zone of 

Cypridea punctata 

Middle Purbeck 

Sub-Zone of 


Lower Purbeck 

Zone of 


Marine 

Portland 

6 

CO 

> C/J 

< 

i « 

D 

•—I

RELATION TO THE EASTERN NEOCOMIAN SEA 547 

sands come to rest at numerous places inland upon Kimeridge Clay, and over 

the Charnwood and Nuneaton Axes they extend on to Oxford Clay. In the 

Weald the discordance is less marked, but even there the Aptian eventually 

oversteps the W T ealden and passes on to the Palaeozoic platform. 1 

And so, as Sir A. Strahan wrote in 1898, 'there is not only in the Isle of 

Wight and in the Isle of Purbeck, but in the South of England generally, 

a well-defined base to the Lower Greensand, above which, and nowhere below 

it, occur the characteristic and purely marine species of that formation, while 

the brackish and freshwater fauna is confined ... to the Wealden group'. 2 

Were we dealing only with the South of England there could be no question 

of drawing the dividing line between the Jurassic and Cretaceous Systems 

anywhere but at this major transgression, which marked the invasion of the 

area covered by the freshwater lake-deposits, containing a purely Jurassic 

fauna and flora, by the Aptian sea with its purely Cretaceous and marine 

assemblage. But when we take a wider area into account the matter assumes 

an entirely different aspect. For in Yorkshire, Lincolnshire and North Germany 

there were two Lower Cretaceous transgressions, the Aptian invasion 

being preceded by a Neocomian one, which left no traces in, and so probably 

did not extend over, the country occupied by our Wealden lake. 

The Neocomian deposits of Yorkshire, Lincolnshire and Norfolk were 

fruitfully studied for many years by Lamplugh, but it is only recently that 

Dr. Spath's elucidation of the ammonites has enabled them to be effectively 

brought into line with the Continental sequence. Everywhere the Neocomian 

deposits rest upon an eroded surface of the Kimeridge Clay and contain at 

their base a bed of phosphatic pebbles, among which are rolled Kimeridgian 

ammonites and other fossils. In Yorkshire the phosphatic pebble-bed (called 

the Coprolite Bed) is succeeded by the Speeton Clay, containing ammonites 

belonging to all the three subdivisions of the Neocomian—the Valanginian, 

Hauterivian and Barremian (though with a number of gaps in their faunas)— 

and overlain by the Aptian. In Lincolnshire and Norfolk the sequence is 

somewhat different, but a similar general succession of ammonite faunas has 

been made out, ascending from the Spilsby Sandstone through the Hundleby 

Clay, Claxby Ironstone, Tealby Clay, Tealby Limestone and Snettisham Clay 

to the Aptian Carstone. Here the earliest ammonites found, in the Spilsby 

Sandstone, are of slightly earlier date than those in the lowest ammonitebearing 

horizon of the Speeton Clay (the Upper part of the Infravalanginian 

or Upper Berriasian) ; 3 but, as pointed out by Lamplugh, the phosphatic 

pebble-bed at the base of the Spilsby Sandstone can without much doubt be 

correlated with the so-called Coprolite Bed at the base of the Speeton Clay. 4 

The two denote but a single transgression of the Jurassic plains by the Neocomian 

sea. 

This northern Neocomian sea was completely excluded from the area of the 

Wealden lake by the London-Ardennes landmass: no sign of marine Neocomian 

deposits exists anywhere on the south of the barrier in England or in 

Northern France. If, however, we follow along the north of the land-barrier 

1 Lamplugh, Kitchin and Pringle, 1923, loc. cit., p. 16. 


3 L. F. Spath, 1924, Geol. Mag., vol. lxi, p. 80, Table. 

4 G. W. Lamplugh, 1896, Q.J.G.S., vol. Iii, p. 159 and Table.


eastward and cross into Germany, we find to the south of Hanover an extensive 

tract of richly ammonitiferous Neocomian clays, evidently a continuation 

of those in Yorkshire and Lincolnshire, and beneath them other freshwater 

beds resembling our Wealden and Purbeck formations. 

Before we can profitably discuss any further the vexed question of the upper 

limit of the Jurassic System, therefore, we must abandon the insular outlook 

which we have maintained hitherto in this book and consider the relations of 

the formations in the classic region around Hanover and Hildesheim. 

II. THE TRANSITION FROM JURASSIC TO CRETACEOUS TIMES IN 

NORTH-WEST GERMANY, AND ON THE JURASSIC-CRETACEOUS 

BOUNDARY IN GENERAL 

The Jurassic and Lower Cretaceous rocks of the neighbourhood of Hanover 

were long ago described in memoirs by Struckmann, Roemer, Brauns and von 

Seebach, and more recently they have received attention at the hands of 

Koert, von Koenen, Salfeld and other geologists. By far the most important 

modern contribution to an understanding of the uppermost part of the Jurassic 

series was made by Koert, who carefully collected the Ostracods from the 

various levels. 

The general succession from the Neocomian to the Kimeridgian is as 

follows: 

SUMMARY OF THE SUCCESSION NEAR HANOVER 

Hils Clays. The Hils Clays, studied with minute care by von Koenen in 

numerous brickyards, especially in the Hilsmulde, contain a full suite of 

Neocomian ammonite faunas, with which Dr. Spath has been able to correlate 

the ammonite succession of the Speeton Clay and its equivalents in Lincolnshire. 

Since the clays are undisputedly of Cretaceous date they only concern 

us here in so far as they provide us with a datum-line. 

Unlike the Neocomian of Lincolnshire and Yorkshire, the Hils Clays do 

not rest non-sequentially upon much older Jurassic beds, with a basal pebblebed, 

but pass down conformably into a thick series of strata like our Wealden. 

The lowest ammonite-bearing marine horizon is the Platylenticeras zone of 

the Lower Valanginian, which is unrepresented in England, but which Dr. 

Spath places between the faunas of the Hundleby Clay and the Spilsby 

Sandstone (see table on p. 546). Immediately above it is the Polyptychinites 

zone or Middle Valanginian, equivalent to the Hundleby Clay. 1 At Hils the 

Platylenticeras fauna has not been found, and the Polyptychinites zone seems 

to rest directly on the Wealden Beds. At other places the basal portion of the 

Platylenticeras zone or marine Lower Valanginian inosculates with the freshwater 

Wealden, so that there are several alternations of marine and freshwater 

strata. 2 On the evidence of this inosculation of the uppermost beds of the 

Wealden with strata slightly older than the Hundleby Clay (which rests on 

the Spilsby Sandstone), Dr. Spath correlates the Wealden of North-West 

Germany with the Spilsby Sandstone and the Infravalanginian of other 

regions. 3 

Wealden. The German Wealden, like the English, is a highly variable 

1 L. F. Spath, 1924, loc. cit., p. 80, Table. 

2 C. Gagel, 1893, Jahrb. Preuss. Geol. Landesanst., vol. xiv, pp. 158-79. 

3 L. F. Spath, 1924, loc, cit.

COMPARISON WITH HANOVER 549 

series of freshwater, lacustrine and deltaic deposits, and reaches a maximum 

thickness not far short of i ,000 ft. Some authors have divided it into Wealdenthon 

above and Wealdensandstein below, suggesting our Weald Clay and 

Hastings Sands, while others have considered it divisible into three, a predominantly 

sandstone division between two clays—the differences depending 

on the place. The sandstones make good building-stones and have been used 

in Cologne Cathedral. Interbedded with them are bituminous, pyritous or 

carbonaceous shales and seams of coal. The flora, like that of our Wealden, 

is purely Jurassic, and so is the vertebrate fauna. The clays are grey or black, 

rarely sandy, with thin-bedded limestones made up of Neomiodon, Unio 

waldensis, Melania strombiformis, Viviparus fluviorum, Cypris waldensis, &c. 

The same fossils occur more rarely in the sandstones; and saurian footprints 

have also been found. 

Freshwater Limestones. Locally at Hilsmulde, Little Deister, Osterwald 

and Nesselberg there are up to 185 ft. of marly, freshwater limestones and 

marls; but they seem to fail near Hanover, at Deister, at Siintel and in the 

Teutoburger Wald, where various writers have described the Wealden sandstones 

resting directly on the next stratum beneath, the Serpulite. Koert 

showed that these limestones yield Cypridea punctata Forbes in almost every 

exposure, and also Physa bristovii Forbes, Hydrobia, Bythinia, Valvata, 

Planorbis and Char a. Some of the beds are described by Koert as crowded 

with C. punctata, like the Ostracod Shales of the Upper Purbeck, and the 

species is found throughout the sections, especially with Planorbis and Char aremains. 

1 

Serpulite. The freshwater limestones pass down, without any sharp 

line of demarcation, into a series of some 50-150 ft. of mixed marine and 

freshwater beds, mainly massive grey limestones in the upper part, and 

grey clays with subordinate limestones in the lower part. This series has 

long borne the name of Serpulite on account of the abundance of Serpula 

coacervata Blumb., which largely composes some of the limestones. The 

marine fauna predominates, but there are many freshwater fossils, including 

Physa bristovii Forbes, Neomiodon angulatam (Sow.), Valvata helicoides 

Forbes. Of greatest significance are the Ostracoda, carefully collected by 

Koert, which include Metacypris forbesii Jones, Cypridea punctata and C. 

dunkeri Jones, 2 clearly a Middle Purbeck assemblage. The marine genera 

recorded are Ostrea, Exogyra, 'Pecten!, Gervillia, Corbula and Actceonina. 

Other fossils stated by Koert to be represented in the collection at Gottingen 

from both the Serpulite and the Middle Purbeck of Swanage are Melanopsis 

harpceformis Dunk. & K., M. attenuata Sow., Nerita valdensis Roem., Litorinella 

elongata (Sow.), Turritella minuta Dunk. & K., Corbula durlstonensis 

Maillard and other Corbulce, &c. 

The Serpulite transgresses the underlying beds down to the Lias and Trias, 

but where the Munder Marls are developed the passage is gradual and conformable. 

Munder Marls. The Munder Mergel, often called Purbeck Mergel, consists 

of up to 1,000 ft. of red and green marls, containing much gypsum and 

1 W. Koert, 1898, Geol. und Pal. Untersuch. der Grenzschichten zwischen Jura und Kreide auf 

der Sudwestseite des Selter\ Inaug.-Dissertation, Gottingen, pp. 23-30. 

2 Ibid., pp. 17-23.


other salts. Fossils, except for Cypris purbeckensis, are rare, but certain beds 

yield such marine species as Gervillia arenaria Roem., Corbula and Serpula 

coacervata\ while other layers, especially towards the top, contain some of the 

same lacustrine forms as the Serpulite—Valvata helicoides Forbes and V. 

sabaudiensis Maillard. The marls are in many respects comparable with the 

Lower Purbeck, with which they have long been correlated by authors, and 

with which Koert's discovery of abundant Cypris purbeckensis accords. 1 They 

have been likened to the marls of the Keuper, and seem to have had a similar 

mode of origin. 

Eimbeckhauser Plattenkalk. The Munder Marls pass down gradually 

and conformably into the Plattenkalk, which is a very widespread formation 

in North-West Germany. It consists of a variable series of peculiar platy, 

bituminous, marly or shaly limestones, some oolitic, separated by marly 

clays, in all up to more than 300 ft. thick. Some of the layers are highly 

impregnated with bitumen. The fossils recorded by various authors include 

Eodonax pellati, Protocardia cf. dissimilis, Corbula alata, C. inflexa, C. autissiodor 

ensis and Modiola autissiodor ensis, all rather abundant, and Isognomon 

bouchardi, Trigonia variegata, Neomiodon cuneatum and N. angulatum. With 

these are still occasionally found Viviparus, Bythinia, Melania and Carychium. 

Gigas Beds. Below the Plattenkalk, and resting on Kimeridge Clay with 

Exogyra virgula (Lower Kimeridge Clay), are the fossiliferous Gigas Beds with 

large ammonites previously known as Ammonites gigas and A. giganteus, and 

supposed to represent the Portland Stone. Salfeld, however, recognized these 

forms as the Kimeridgian genus Gravesia. The beds consist of marls with 

bands of limestone. They also contain Exogyra virgula. 

[Lower] Kimeridge Clay, with Exogyra virgula, below. 

Until recently the correlation of this succession with that in Dorset w T as 

considered straightforward. The view held by the pioneers, Roemer, 

Struckmann and Seebach, and greatly strengthened by Koert, was that the 

Gigas Beds, with or without the Plattenkalk, represent the Portland Stone, 

and that the remaining strata up to the base of the Wealden are equivalent to 

the Purbeck Beds. This is the correlation set forth in all the text-books, such 

as the Traites of De Lapparent and Haug, and, so far as the strata above the 

Gigas Beds are concerned, there is much to be said in its defence. 

In 1914 Dr. H. Salfeld introduced a revolutionary classification, based on 

his discovery that the large ammonites of the Gigas Beds belonged, not to the 

species of the Portland Stone, but to the superficially similar genus which he 

called Gravesia, characteristic of the Lower Kimeridge Clay in England. As 

a result of this correction, he sought to discover representatives of the higher 

Kimeridgian and Portlandian Beds amongst the overlying strata in Germany 

usually assigned to the Purbeck. Von Koenen had already suggested that the 

Serpulite might perhaps be correlated with the Portland Stone, 2 and Salfeld 

now took up the idea and proclaimed it as his opinion that the underlying 

Munder Marls and Plattenkalk probably bridged the zones of 'pallasianus' 

[Pavlovice], pectinatus and gorei. 3 As the solitary representative of the Purbeck 

1 W. Koert, 1898, loc. cit., pp. 16 and 17. 

2 Von Koenen, 1900, 'Oeber das Alter des norddeutschen WalderthonV, Nachrichten des 

K. GeselL Gottingen, aus 1899, pp. 311-14. 

3 H. Salfeld, 1914, loc. cit., p. 173.

CORRELATION OF THE HANOVER SUCCESSION 551 

Beds, he left the impersistent Freshwater Limestones (Koert's Upper 

Purbeck). 

Salfeld's correlation seems to be based solely on the three following points : l 

(1) in one place, in the conglomeratic and highly transgressive Serpulite, 

von Koenen found a single specimen of Belemnites cf. absolutus Fischer, 

a species which is also found in the Titanites (giganteus) zone (see von 

Koenen, 1900, p. 313). 

(2) the abundant Serpulce in the Serpulite recalled to Salfeld portions of the 

Cherty Series of the Isle of Portland, likewise crowded with Serpulce. 

(3) the Serpulite marks a period of marine transgression, whereas in England 

and North France, he states, the sea withdrew after Titanites 

(giganteus) times; therefore the Serpulite is unlikely to be later than the 

Titanites zone. 

Against these considerations I would draw attention to the following: (1) 

The single belemnite found in the Serpulite (even if its identification were not 

beyond suspicion, but it is only compared with B. absolutus Fischer) could 

never be relied upon for dating purposes, for it might have been derived from 

an older formation; the associated pebbles are derived from all parts of the 

Jurassic and even the Trias. 2 Andree has pointed out in another connexion that 

not much value can be attached to this single find. 3 (2) The Serpula of the 

Portland Cherty Series is S.gordialis, whereas that of the Hanoverian Serpulite 

is S. coacervata, a species which Koert identified in the Middle Purbeck of 

Swanage. 4 (3) The statement that the sea withdrew altogether after Titanites 

times is incorrect, for there was a widespread marine invasion in the Middle 

Purbeck (see above, pp. 518, 531, 538). 

Against the slender arguments adduced by Salfeld must be set the resemblance 

of the whole of the fauna and most of the lithology of the Munder 

Marls, Serpulite, and Freshwater Limestones to the Purbecks. There is, in 

fact, definite evidence for believing that these three formations represent the 

Lower, Middle and Upper Divisions of the Purbeck Beds: (i) In the Munder 

Marls there is the zone fossil Cypris purbeckensis, which Koert says is abundant 

at certain horizons, as well as the general lithology and the masses of gypsum 

to suggest the Marls-with-Gypsum of the Lower Purbeck; the gypsum and 

other salts are in evidence not only in Dorset and the Weald 5 but also in the 

Charente and the Jura Mountains. 6 (2) In the Serpulite, Koert's discovery of 

the Ostracods Metacypris forbesii, Cypridea punctata and C. dunkeri, taken 

with the predominance of limestones and the evidence of a marine transgression, 

calls for correlation with the Middle Purbeck. (3) The Freshwater 

Limestones correspond well with the Upper Purbeck, even to the abundance 

of the zone-fossil, Cypridea punctata, to the exclusion of other Ostracods. 

Von Seebach classed the Plattenkalk also with the Purbecks, 7 but the 

marine lamellibranch fauna is that of the Portland Beds. The abundance of 

1 H. Salfeld, 1914, loc. cit., pp. 158-9. 

2 H. Stille, 1905, 'Muschelkalkgerolle im Serpulit des nordlichen Teutoburger Waldes*, 

Zeitschr. deutsch. geol. Gesell., vol. lvii, p. 168. 

3 K. Andree, 1908, Neues Jahrb.y Beilage Band, xxv, p. 389. 

4 W. Koert, 1898, loc. cit., p. 53. 

5 See above, p. 539. 

6 At la Riviere, south-west of Pontarlier, there is a gypsum works, where the Lower Purbeck 

gypsum is exploited as in the Weald and formerly in Durlston Bay. (Maillard, 1884, M6m. 

Soc. pal. Suisse, vol. xi, pp. 9-26 and map.) 

7 K. von Seebach, 1864, Hannoversche Jura, p. 59.


bitumen, also, it may be remembered, was one of the characters of the Portland 

Beds in the Kentish borings, where, especially at Brabourne, 'both the 

limestone and the muddy sandstone were strongly impregnated with bitumen, 

which had frequently exuded in brown pitchy drops and flakes along joints 

and other crevices'. 1 

When all things are considered, therefore, there seems good reason for 

supposing that, however imperfectly the Portland Beds and Upper Kimeridge 

Clay may be represented in Hanover (the latter perhaps cut out entirely by 

a major non-sequence represented in part by the very considerable ones below 

our two Midland Lydite Beds), the Purbeck and Wealden Beds are well 

developed, the Purbecks more than twice as thick and the Wealden not quite 

half as thick as in Southern England. So great a thickening of the Purbeck 

Beds would probably cause no surprise if the full sequence of marine equivalents 

in other parts of Europe were more properly understood. Dr. Spath, 

who has recently studied the question, states that 'recent researches indicate 

that there is room for a very long and important epoch between the Cretaceous 

and the Portlandian, an epoch for the widely-scattered marine equivalents of 

which the terms "Purbeckian" or "Aquilonian" seem inappropriate'. 2 

The reason for this long digression to inquire whether the North German 

Purbeck-Wealden sequence is homotaxial or contemporaneous with that of 

Southern England, although accumulated in a separate basin, will be evident: 

it provides us with a common factor for linking up the Wealden lake-deposits of 

Southern England with the marine Neocomian in Lincolnshire and Yorkshire. 

If the German Purbeck-Wealden can be correlated with the English, then at 

least the upper part of the Wealden Beds south of the London-Ardennes ridge 

is contemporaneous with the Spilsby Sandstone to the north of the ridge. 

In view of this correlation a new interest attaches to the transgression of the 

attenuated upper part of the Wealden Beds as it approaches the London 

Palaeozoic rocks under the Weald of Kent, and again in the Boulonnais and 

in Belgium (where the famous Iguanodon deposits of Bernissart, near Mons, 

rest on a channelled surface of the older rocks). The same transgression of 

the upper part of the Wealden has been reported in Germany. The Weald 

Clay rests on Bajocian at Sehnde, near Hanover, and a boring at Borgloh- 

Osede has been said to show it in contact with Sequanian; borings on the 

borders of Westphalia and Holland proved it again, much diminished in 

thickness, resting on Trias. 3 If these records have been rightly interpreted, 

the German Upper Wealden reaches out, as it were, to meet the Anglo- 

Franco-Belgian on the other side of the London-Ardennes ridge. Such a 

transgression on both sides of the ridge speaks eloquently in support of the 

palaeontological correlation with the Spilsby Sandstone and other basementdeposits 

of the highly transgressive Neocomian in Lincolnshire and Yorkshire. 

That some of the transgressive deposits are marine and others lacustrine 

is unimportant, since a general subsidence of the ridge would have the same 

1 G. W. Lamplugh, 1911, loc. cit., p. 43, and see other borings. 

2 L. F. Spath, 1923, Q.J.G.S., vol. lxxix, p. 304. For the stage-name he uses Oppel's term 

Tithonian. 

3 De Lapparent, 1906, Traite, p. 1310, where references are given. See, however, K. 

Andr£e, 1908, Neues Jahrb. fur Min. &c.y Beilage Band, xxv, pp. 389-90, who throws doubt 

on some of these interpretations. He believes the marls with gypsum and anhydrite at 

Borgloh-Osede, which Gagel called Weald Clay, to be the Munder Marls.

TRANSGRESSION ROUND THE LONDON LANDMASS 553 

effect on both sides whether the water were fresh or salt; moreover the subsidence 

led, as w r e have seen, to a mingling of the fresh water and the sea in the 

neighbourhood of Hanover. 

If this subsidence was not purely a local one affecting only the London- 

Ardennes ridge, then we begin to see some justification for De Lapparent's 

proposal to divide up the Wealden Beds so as to assign the Weald Clay to the 

Cretaceous and the Hastings Beds to the Jurassic. 1 But such a partition of a 

perfectly continuous series is a highly unnatural one, and all the arguments 

used against the separation of the Wealden from the Purbeck Beds apply 

again with equal force. Since the lack of fossils of any chronological value 

makes it impossible to determine which portions of the fully-developed 

sequence are represented in the attenuated and overstepping strata at the 

margins of the basin, no line could be drawn with any certainty in the Wealden 

Beds of the South of England. Salfeld has protested also against the attempt 

to draw any such line through the Hanoverian Wealden. 2 Further, it may be 

questioned whether any separation of the transgressive from the non-transgressive 

portions of the formation is justifiable on theoretical grounds; for the 

process of subsidence of the land was probably continuous and the overlap 

progressive throughout the life of the Wealden lakes. The accumulation of 

over 2,000 ft. of sediments proves the bed of the English lake to have sunk at 

least that amount during the Wealden period. 

Once again we seem driven to look farther afield for relevant facts indicating 

where the dividing line between Jurassic and Cretaceous is to be drawn in 

the South of England. Comparison with Germany has shown us that our 

Wealden Beds are Neocomian, and therefore Cretaceous. It now remains to 

see what are the relations of the Neocomian formation, when fully developed 

in its marine facies, to the Purbeck or Portland Beds. For this we have to pass 

to the South of Europe. 

In the Jura Mountains and the surrounding districts to the west and northwest, 

ammonite-bearing deposits, earlier than any found in the Neocomian 

of North-West Europe, and belonging to the Lower Infravalanginian, rest 

directly upon a thin but widespread representative of the freshwater Purbeck 

Beds. Locally they even inosculate with the upper portion of the Purbecks 

just as do the Platylenticeras deposits of the Lower Valanginian with the top 

of the Wealden in Germany. 3 So closely do the Purbeck Beds here resemble, 

in their lithic characters and their fauna, those of England, that the conclusion 

that they are at least homotaxial is unavoidable. Moreover, they rest 

upon apparently authentic Portland Beds (correlated by several authors with 

the Plattenkalk). Maillard, who monographed the freshwater fauna, concluded 

his resume by stating emphatically 'the Purbeckian of the Jura, reduced 

to two subdivisions, corresponds exactly with the Purbeckian of Hanover as 

restricted to the Munder Marls and the Serpulite, and probably with the 

Lower and Middle Purbeckian of England. . . . There is no gap between the 

Purbeckian and the [Infra]valang[in]ian, which is the time-equivalent of the 

Wealden.' 4 In support of his conclusions he figured from the Jura a number of 

English and Hanoverian Purbeck fossils, including Cyprispurbeckensis Forbes. 

1 De Lapparent, loc. cit., p. 1262. 


3 G. Maillard, 1884, loc. cit., p. 136; stated to have been observed also by Benoit, Bertrand 

and Gilli£ron. 

4 G. Maillard, 1884, p. 144.


Koert endorsed Maillard's statements after his careful study of the Purbeckian 

of the Selter in North-West Germany, and the table which he published, 

indicating the numerous species in common, leaves little doubt as to the 

equivalence of the Purbeck Beds in the three areas. 1 

In the Jura Mountains these beds are so insignificant in thickness that 

Maillard regarded them as merely a freshwater facies of the upper part of the 

Portland Stone, and this doubtless influenced Haug, who classed them in this 

text-book as a substage of the Portlandian. 2 The inosculation of the top of the 

Purbeck Beds with the base of the marine Neocomian then led to the fallacious 

conclusion that part of the Portlandian in some places might be contemporaneous 

with part of the Neocomian in others. 

What really takes place is that the Purbeck Beds, when followed towards 

the Alps, pass laterally into marine strata, resembling and perfectly conformable 

with the Portland Beds—the Tithonian formation. As its name, derived 

from Greek mythology, implies, 3 this formation is not only conformable with, 

but also in some ways foreshadows the Cretaceous, although it is always 

classed with the Jurassic. Here in the deeper parts of Tethys we have, in fact, 

a continuous sequence of marine deposits linking the Jurassic System with 

the Cretaceous on the one hand and with the Triassic on the other. Here no 

earth-movements such as disturbed the shallower sea-bed of North-Western 

Europe were profound enough to cause great breaks in the sedimentation 

or to give rise to important unconformities. This is no region in which to 

establish convenient stratigraphical subdivisions or to set other than palaeontological 

boundaries to the formations. 

The Tithonian is comparable (on a smaller scale) with the Tethyan Trias, 

in that both formations pass laterally over wide areas in North-Western 

Europe into freshwater and terrestrial formations. The continental episode 

represented by the Permo-Trias (or 'Epiric') formation marks one of the 

major interludes in the sedimentary history of North-Western Europe and is 

made use of to separate the Primary from the Secondary rocks. 4 The difficulties 

of correlating it with the marine strata and of deciding to which 

formation it should rightly be assigned are illustrated by the still lively 

controversy. The one point upon which all now seem agreed is that the 

Jurassic System should begin with the advance of the Rhaetic sea from the 

shrunken Tethys across the desert plains and salt lakes of North Germany 

and Britain. This advance, which, as we have seen, reached to the North of 

Scotland, brought in a new era and with it we began this book. If we are to 

be consistent we must make use of the corresponding datum in choosing the 

base of the Cretaceous System. The succession in the Jura and the Rhone 

Basin in general shows us that the continental Purbeck episode, of which the 

lacustrine and terrestrial deposits extend from the borders of the Alps to 

North Germany and Central England, was brought to an end by the marine 

invasion of the Infravalanginian. This, and no other, should be the basal 

member of the Cretaceous. 5 

1 W. Koert, 1898, loc. cit., pp. 52-3. 

2 E. Haug, 1911, Traite de Geologiey vol. ii, pp. 1075 et seq. 

3 Tithon was the spouse of Eos (Aurora), goddess of the dawn. 

4 See R. L. Sherlock, 'Correlation of the British Permo-Triassic Rocks*, P.G.A., 1926, 

vol. xxxvii, pp. 1-72, and 1928, vol. xxxix, pp. 49-94. 

5 For a convincing exposition of this principle of using widespread gaps in sedimentation

INADEQUACY OF BRITISH EVIDENCE 555 

Complication arises from the fact that the Infravalanginian transgression 

did not affect the whole of the area covered by the Purbeck lakes and swamps. 

The regions where the Purbeck Beds were thickest—North Germany and 

Southern England—became isolated by land barriers, and, although they too 

were depressed at the same time as the sea found its way north of the London 

landmass and over the plains of Lincolnshire and Yorkshire, they did not sink 

beneath the sea but formed vast lakes. The lacustrine fauna of the Purbeck 

era there survived with but little modification, for it found itself in an environment 

differing little from that to which it was already adapted. The land, too, 

which supplied the flora washed into the Wealden lakes, was the same as that 

which surrounded the Purbeck swamps and lakes; and this in turn was 

nothing but an extension of the old Jurassic land-surface. Consequently the 

terrestrial fauna and flora still remained essentially Jurassic. 

Thus we see that in the South of England (and in North Germany) we are 

in an abnormal area. We cannot judge of the events at the close of Jurassic 

and the dawn of Cretaceous times without travelling far afield, for we have 

none of the right kind of evidence, and the little that we have is misleading. 

Although palaeontologists and palaeobotanists affirm that the land and 

freshwater fauna and the flora of the Wealden Beds cannot be separated from 

those of the Purbecks, the Wealden Beds are contemporaneous with Cretaceous 

marine strata on the other side of the London landmass and in the Jura 

Mountains, while the Middle Purbeck incursion of marine animals proves 

that the Purbeck Beds were laid down at a time when the fauna in the neighbouring 

sea was still purely Jurassic. 

Lacustrine mollusca are traditionally resistant to the forces of evolution, 

and their assemblages stable, while terrestrial faunas and floras also may be 

expected to survive unless wiped out by wholesale marine transgression or 

revolutionary changes of climate. If consideration of them, on their rare 

occurrences in the stratigraphical record, were allowed to outweigh the 

evidence of the normal marine succession, chaos would result. When Messrs. 

Topley and Jukes-Browne reported to the International Geological Congress 

in 1855 that 'the separation of Purbeck from Wealden is a mistake due only to 

the occurrence in Purbeck of one or two Oolitic forms of marine life, ... is 

unnatural', 1 they were displaying an outlook anything but international. 

Further, they were disregarding the principles of correlation, for the 'one or 

two Oolitic forms of marine life' are worthy of more regard than all the rest 

of the fauna and flora together. No matter if Jurassic mammals and reptiles 

still peopled a Jurassic land-area, about lakes where an imprisoned assemblage 

of Jurassic fishes and freshwater mollusca still survived; once the Cretaceous 

sea with its teeming new population was already encroaching over the 

Continent, then Cretaceous times had begun. When Fitton and Webster, in 

the eighteen-twenties, united the Purbeck and Wealden series 2 they knew 

nothing of the marine provinces beyond our own islands, and more than 

twenty years were still to elapse before the discovery by Forbes of the few 

precious marine species in the Middle Purbecks. 

over continental areas as guiding lines in stratigraphical classification see C. Diener, 1925, 

Grundzuge der Biostratigraphie, pp. 160-1. 

1 Compte Rendu, Congres geol. int., 3 me Session, Berlin, 1885, p. 453. 

2 T. Webster, 1826, Trans. Geol. Soc. [2], vol. ii, p. 44; W. H. Fitton, 1827, ibid., vol. iv, 

pp. 105, 159.


The conclusion, therefore, seems to be that, since the relatively sudden 

change of sedimentation at the commencement of the Wealden Series may 

be due to the same earth movements as those which elsewhere caused the 

Neocomian transgression to begin, however unsatisfactory it may be in 

the abnormal Southern English area, it is the only available datum-line at 

which to draw the important boundary between the Jurassic and Cretaceous 

Systems.

PART IV 

CHAPTER XVIII 

PALAEOGEOGRAPHICAL CONCLUSIONS 

HAVING now reviewed briefly the principal geological data, we are better 

qualified to approach the most fascinating but at the same time the most 

dangerous part of our subject, the palaeogeography. This entails leaving the 

comfortable society of ascertained facts and venturing into the alluring but 

treacherous realms of deduction, inference and speculation. It is to the guiding 

of such speculations, however, that the data set forth in the stratigraphical 

part of this book are directed, and to leave the mass of facts as they stand 

would be to abandon them as meaningless. As Prof. Watts has said: 'It is to 

the elucidation of Earth History that all branches of geology are contributory, 

and from a knowledge and interpretation of the details of this history that the 

applications of geology proceed. . . . We must be accurate in our geological 

facts; but we may, as Darwin advised us, speculate freely.'1 To do justice to the palaeogeography of the Jurassic period would require 

a second volume almost as large as this; for the subject is no longer a mere 

constructing of palaeogeographical maps, but a full-blown science, containing 

within it many -ologies. If we were to pursue it thoroughly, we should 

have to proceed systematically from the points of view of palaeorography, 

palaeohydrography, palaeoceanography, palaeobiogeography, palaeoclimatology, 

palaeoastronomy, and many others. 2 No such attempt is possible here, 

at the end of a single volume already swollen beyond its intended dimensions; 

and consequently the following brief remarks may appear superficial. But it 

should be observed that certain fundamental aspects of palaeogeography have 

already been dealt with at greater length in Part II. We have already pictured 

the trough sea that stretched across the British area between the western and 

the eastern landmasses, from Kent and Dorset north-eastward to Yorkshire 

and north-westward by way of Shropshire, the Irish Sea and Antrim to the 

Hebrides; and we have examined the stages by which the bed of the sea sank 

progressively deeper, keeping pace with the accumulation of sediment. Now 

it remains to review briefly certain other matters upon which light is shed by 

the stratigraphy: (i) the distribution of the more important marine organisms, 

which give some indication of the conditions of life in the seas—especially the 

depth (this comes under 'palaeobiogeography' or 'palaeoecology'); and (2) the 

probable extent of the Jurassic seas over regions where no trace of sediments 

is to be found; the height of the surrounding land; and the connexions between 

the British seas and those on the Continent or elsewhere (palaeogeography 

proper, or 'palaeocartography'). 

I. SOME ASPECTS OF PALAEOECOLOGY 

(a) The Distribution of Corals 

The reef-building corals are probably the most important of all marine 

organisms for the palaeogeographer. At the present day, although there is an 

1 W. W. Watts, 1911, Address to the Geological Society, Q.J.G.S., vol. lxvii, p. lxiii, 

2 E. Dacque, 1915, Grundlagen und Methoden der Palaogeographie, pp. 1-499. 

*.-)437l Q q

5 5 8 PALAEOGEOGRAPHY 

almost boundless diversity of types and forms, they all live under the same 

conditions, within definite limits of depth, temperature, salinity and clarity 

of water; it is therefore reasonable to infer that where reef-building corals 

flourished in the past, similar conditions obtained. Since sheets of coral are 

intercalated at a number of horizons in the Jurassic System in various parts 

of the country, we are provided with a number of valuable (because definite) 

controls. We may not postulate abysmal depths for the deposition of sediments 

in which any coral growth took place. Further, it is improbable that 

there was a great depth of water during the formation of any part of a series 

in which coralline intercalations are so frequent as in the English Jurassic; 

otherwise we have to imagine an unlikely degree of activity of the sea-bed, 

alternately rising and sinking through prodigious distances, every time the 

bottom was brought within the necessary reach of the surface to enable coral 

growth to become established. Moreover, since thin and irregular sheets of 

coral sometimes completely overspread the troughs of deposition from side to 

side, we know that at those times the depth of water even in the centres of the 

troughs cannot have exceeded 120-50 ft. (see p. 53). 

It is difficult to classify the Jurassic coral sheets or to find analogues in 

modern seas. They are neither barrier reefs nor atolls, for they seldom exceed 

20 ft. in thickness, and no suggestion of atoll shape has been detected. On the 

other hand, although many of them evidently grew far from any shore, and so 

are hardly comparable with the best known and most typical fringing reefs 

(such as those along the steeply-shelving coasts of oceanic islands or the Red 

Sea), it would seem that they may be grouped with Fringing Reefs as understood 

in Darwin's classification; for the width of a fringing reef, as Darwin 

pointed out, depends entirely on the degree of inclination of the submarine 

slope, combined with the fact that the corals cannot grow below a certain 

depth. Thus when the sea is very shallow and the coast gently-shelving, there 

is nothing to prevent the fringing reefs spreading almost indefinitely. Then, 

as Darwin found in the shallows of the Persian Gulf and the East Indian 

Archipelago, 'the reefs lose their fringing character and appear as separate 

and irregularly scattered patches, often of considerable area' (see p. 394). 

It is noteworthy that the only two localities where uninterrupted coral rock 

exceeding 20 ft. in thickness is known are at North Grimston (p. 423) and in 

Kent (especially in the borings at Brabourne and Dover; p. 438). North 

Grimston lies on the southern margin of the Yorkshire Basin, against the 

flank of the relatively-stable (non-subsiding) axis of Market Weighton; the 

Kent localities are on the margin of the Wealden trough, close to the flank of 

the London landmass. As these are the only truly fringing (marginal) reefs 

known, the idea suggests itself that the prevailing thinness of the coral sheets 

elsewhere may be due to frequent periodic subsidences having interrupted 

their growth, perhaps carrying them below the 150 ft. limit, or admitting 

muddy or sandy currents, before they had time to attain any greater thickness; 

and that it was only at the margins of the troughs and near the stable axes that 

coral growth was able to keep pace with subsidence. The borings through the 

Corallian rocks in Kent lead to the surmise that if the marginal Inferior Oolite 

deposits in the west had been preserved, between the Cotswold escarpment 

and the Welsh mainland, the thin and scattered bands of coral in the Cotswolds 

would have been found to join up as they were traced westward over the Vale

DISTRIBUTION OF CORALS 559 

of Gloucester and the Vale of Berkeley, until they passed into thick fringing 

reefs along the Palaeozoic land margin. There is, indeed, evidence of a thickening 

of the existing coral bands in this direction. 

The history of coral growth in the British Jurassic seas is interesting. Very 

rarely, isolated fragments of 

coral are met with in the Rhaetic 

Beds (e.g. p. 108), and scattered 

examples and seams, chiefly of 

Montlivaltia, occur in many 

places in the Lower Lias—even 

commonly enough to form an 

ornamental stone in one place 

in the davoei zone (Banbury 

Marble, p. 134)—but in general 

the Liassic sea was too muddy 

for coral growth to flourish. In 

two widely separated localities, 

however, in the neighbourhood 

of the Cowbridge Island, 

Glamorgan, and in Skye, corals 

became well established in early 

Lower Lias times (pp.127, 

Here there was apparently unusually 

clear water. It is possible, 

too, that the building of 

calcareous structures was facilitated 

in the neighbourhood of 

the Mendip Archipelago by the 

solution of the Carboniferous 

Limestone of which the islands 

were composed, and in Skye by 

the solution of the neighbouring 

outcrops of Durness Limestone. 

The coral fauna of the 

Sutton Stone in Glamorgan is 

a rich one, but the area over 

which it occurs is small. 

It was not until the Inferior 

'RINGSTEAD CORAL 

BED ( COR- Kl M) 

FIG. 92. Map showing the distribution of Jurassic 

coral reefs in Britain. Existing fossil coral reefs black; 

extensions for which there is more or less indirect or 

strong presumptive evidence dotted. 

Oolite period that coral growth covered large areas in England. It then 

became the most characteristic feature of the Cotsw r old and the Lincolnshire 

Limestone provinces. Although, as just mentioned, most of the 

Inferior Oolite reefs, of which so much of the Cotswold Hills are the 

detritus, probably lay in the main west of the present outcrop and were 

destroyed by the excavation of the Severn Valley, some true coral reefs 

remain. The earliest and perhaps the best-developed (15-20 ft. thick) is 

found between the Pea Grit and the Lower Freestone (murchisonce zone) 

in the neighbourhood of Stroud, where the Oolite escarpment draws close 

to the Palaeozoic tract; and thence it can be traced for some miles along the 

escarpment, as far as Crickley Hill, Coberley and Cowley, but it dies out


towards the north-east. 1 In the same district a Middle Coral Bed appears in 

the Oolite Marl (bradfordensis zone), and this can be traced to Leckhampton 

Hill ; 2 but neither this nor the last extends south of the South Cotswolds, the 

region of the Mendips and the rest of Somerset and Dorset being a noncoralline 

province. Finally, in Upper Inferior Oolite times a new sheet of 

corals appears all along the South Cotswolds, comprising the same species as 

the two earlier reefs, but spreading over a wider area (p. 240). This, the Upper 

Coral Bed (truellei zone), for the first time encroaches on part of the previously 

non-coralline province to the south, for it continues through the Bath district 

and on to Dundry Hill, and corals were rolled round the east end of and 

beyond the Mendips, being found as far away as Bruton (p. 237). 

In the eastern counties patches and straggling sheets of coral w r ere formed 

all over the basin of deposition of the Lincolnshire Limestone, probably at 

several different dates or more or less continuously in different places (p. 210), 

but the stratigraphy of this district still remains to be worked out. It may be 

presumed that the two basins of Lincolnshire and the Cotswolds were in open 

communication north of the present outcrop, divided only by a belt of shallows 

over the Vale of Moreton Axis (p. 67). 

In the Great Oolite period conditions in the Cotswolds-Lincolnshire province 

were similar to those of Lower Inferior Oolite times, at least during the 

deposition of the White Limestone and (in the Cotswolds) earlier. Corals are 

abundant in the White Limestone from the neighbourhood of Bath to mid- 

Lincolnshire ; but there is nothing entitled to be called a reef, the coral beds 

rarely exceeding 2 or 3 ft, in thickness. There is no doubt, however, that the 

corals in these beds are often in the positions where they grew, for the beds 

are lenticular in shape and contain perfectly-preserved specimens of delicate 

branching varieties, standing erect. The coralline province was then coextensive 

with the area where the Great Oolite limestones were forming. In the 

Mendip district and farther south, as in Lower Inferior Oolite times, there 

were no corals; while north of the Market Weighton Axis, as before, deltaic 

conditions held sway. The species in the Great Oolite are for the most part 

new, but perhaps 10 per cent, are survivals from the Inferior Oolite. Although 

the coral beds are so thin, some of them can be traced intermittently over considerable 

areas on the same horizons, and, since there are a number of horizons, 

the Great Oolite limestones are on the average probably as richly coralliferous 

as those of the Inferior Oolite. Coral growth seems to have been extinguished 

by the disturbed conditions with strong currents which gave »ise to the 

Forest Marble, when this facies, which may be regarded as a modified extension 

of the deltaic ('estuarine') type of Yorkshire and Scotland, spread south 

over both coralline and non-coralline provinces alike. 

The next burst of coral growth was in the Corallian period. It w r as the 

greatest of all, and all the species were new. After the general shallowing and 

clarifying of the sea which heralded the second phase of the Oxford Clay 

cycle and is attested by the piling up of the Lower Calcareous Grit sandbanks, 

coral growth sprang up in widely separated parts of England. The earliest 

reef appeared in the Hackness Hills on the north side of the Yorkshire Basin 

(Hambleton Oolite Series) (p. 429). South of the Market Weighton Axis, the 

1 T. Wright, 1868, 'On Coral Reefs, Present and Past,' Proc. Cots. N.F.C., vol. iv, p. 149. 

2 Ibid., p. 151.

CORAL FAUNAS 561 

earliest reefs preserved are in the lower part of the Berkshire Oolite Series in 

Wiltshire. They consist of small patches of true reef-coral, which were soon 

smothered by deposits of Nothe (or Highworth) Clay and Bencliff (or Highworth) 

Grit (p. 400 and fig. 69). The main burst of coral growth in this part of 

England came later, in the Osmington Oolite period, when more or less continuous 

reefs stretched for forty miles from the neighbourhood of Oxford to 

Calne, in Wiltshire (fig. 66) and again over a large area in Kent, where they 

probably continued into the succeeding period. At the same time an isolated 

reef appeared at Upware near Cambridge; but south of Calne, in Dorset, 

and in most parts of Yorkshire, oolites were deposited at this time. 

Towards the end of the Osmington Oolite period, and in the succeeding 

Glos Oolite period, coral growth attained its maximum in Yorkshire and at 

Upware, while in Wiltshire it extended southward to Steeple Ashton, and 

coral debris even reached North Dorset (p. 388). At all of these places the 

reefs and coral debris overlie the main mass of the Osmington Oolite, into 

which those of the Oxford-Calne area pass laterally. 

With the incoming of the Sandsfoot Clay (and in Yorkshire the Grimston 

Cementstone) at the beginning of the next cycle (p. 54) coral growth in 

England was almost extinguished for good, although on the Continent it 

continued through the Kimeridgian period. The thin Ringstead Coral Bed, 

at the top of the Upper Calcareous Grit, testifies to a recrudescence of coral 

growth somewhere in the vicinity, either off the Purbeck coast or under the 

Chalk Downs; but the exact location of the reef, if one existed, is unknown 

(p. 379). Still later, in Sutherland, considerable masses of reef-building coral 

grew in the peculiar conditions prevailing there during the time of the Lower 

Kimeridge Clay (Aulacostephanus zones) (p. 476). 

The Portland Beds contain thin bands of corals in one or two localities, but 

usually they are wholly absent, and there is no sign of anything like true 

reef-formation having occurred at this period in any part of Britain. 

One of the most important and suggestive aspects of coral reefs is their 

influence upon the rest of the fauna. 

It has been shown how, in the only reefs that have been studied from this 

point of view—those in the Corallian Beds—a small assemblage of mollusca, 

comprising certain lamellibranchs and gastropods, not closely related to one 

another, are always found in association with the corals and seldom if ever 

away from them (p. 397). More important than this, however, are the much 

larger assemblages of mollusca which appear to have found the proximity of 

coral reefs uncongenial, since they have been shown to be seldom found in any 

quantity in association with them. Among the lamellibranchia this mutual 

exclusiveness between the coral-dwelling and other forms is especially 

noticeable in the genera Trigonia, Lima, Gervillia, Isognomon, Pinna, &c., of 

which the large and fragile species occur in great profusion in shell-banks in 

the non-coralline area, but are only found occasionally (and then usually in 

fragments) among the corals. There may or may not be a causal connexion, 

but it is evident that these large and brittle lamellibranchs are mechanically 

unsuited to a coral habitat, where they would have to withstand the pounding 

of surf and strong currents. The same applies still more forcibly to the 

floating ammonites, whose shells would be doomed to destruction if they


wandered or were driven by winds or currents too close to the reefs. It is, 

therefore, interesting to notice that ammonites are not only scarcely ever found 

actually among the reefs, but that they are always rare in coralline provinces. 

This mutual exclusiveness on the part of ammonites and corals has hitherto 

been little appreciated; but the fact that either the conditions which favoured 

coral growth were unfavourable to ammonites, or else that the conditions 

produced in the vicinity of coral reefs provided an unfavourable habitat, 

explains many of the anomalies in the distribution of ammonites upon which 

altogether different constructions have been put. 

(b) The Distribution of Ammonites 

Buckman drew attention to the fact that in certain formations ammonites 

are abundant all over the British area, from Dorset to the North of Scotland; 

but that in other formations, notably the Oolites, they abound and are well 

preserved only in certain districts, while in other districts only a few miles 

away they may be unaccountably scarce. Moreover, he pointed out that in 

the districts in which ammonites are scarce, such few specimens as are found 

are more or less broken or worn and frequently have Serpulce or oysters 

attached; in fact they bear signs of having been drifted into their present 

positions after death. 1 The abundant and well-preserved ammonites he called 

autochthonous, 2 or autochthones, as distinct from those which give evidence 

of having been drifted away from some district where they were autochthonous. 

The changing history of ammonite distribution may be summarized as 

follows (the Ages and their equivalents are shown in Table IV, p. 24): 

Ages. Ammonite Distribution. 3 

Pre-Psiloceratan During the deposition of the Rhaetic and Prt-planorbis 

Beds ammonites seem to have been completely excluded 

from the British area. 

Psiloceratan-Cana- Autochthonous ammonites all over Britain. 

varinan 

Ludwigian-Sonninian Autochthonous ammonites abundant in the Dorset-Somerset 

area, including Dundry Hill (north of the Mendip 

Axis), and also in the Hebrides; drifted in the Cotswolds 

Stepheoceratan 

Parkinsonian 

Zigzagiceratan and 

Tulitan 

Early Clydoniceratan 

and Lines, areas; none in Yorkshire. 

As before, but in addition ammonites spread over the 

Yorkshire Basin (Scarborough Limestone). 

Ammonites still common in the Hebrides and in Dorset, 

but retreated from Yorkshire, and from Somerset, as 

far south as the Yeovil-Sherborne district. 

Ammonites common in the Normandy-Dorset-Somerset 

area; north of this, in the Cotswolds and Lines, areas, 

rare and mostly drifted. None in the Hebrides or 

Yorkshire. 

Ammonites retreat altogether from the British area, while 

deposits somewhat similar to the 'estuarines', previously 

confined to the North, spread all over England (Forest 

Marble). 

1 S. S. Buckman, 1922, T.A., vol. iv, pp. 19-20. 

2 Oxford Diet.: 'sprung from that land itself'; i.e. aboriginal. 

3 Compare a table by Buckman, 1922, loc. cit., p. 19, drawn up, however, to illustrate a

DISTRIBUTION OF AMMONITES 563 

Ages. Ammonite Distribution. 

Late Clydoniceratan Autochthonous ammonites again abundant, in the Lower 

Cornbrash, from Normandy as far north as the Market 

Weighton Axis; north of this, deltaic conditions or no 

deposition at all. 

Macrocephalitan- Autochthonous ammonites all over Britain. 

Early Perisphinctean 

Late Perisphinctean Autochthonous ammonites retreat from all parts of England 

with the general spread of coral reefs (Osmington and 

Glos Oolite Series); strata not exposed in Scotland. 

Ringsteadian (or Autochthonous ammonites all over Britain (except when 

Prionodoceratan ?)- the sea retreated from the North in Portlandian times). 

Gigantitan 

Post-Gigantitan During the Purbeck and Wealden periods ammonites 

appear to have been once more completely excluded 

from the British area. 

Buckman explained these facts by postulating movements along axes of uplift, 

which he supposed cut off certain areas from free communication with 

the open ocean. Thus, to account for the abundance of autochthonous 

ammonites in the Dorset and Somerset area and on Dundry Hill in the Lower 

Inferior Oolite, and their absence from the Cotswolds, he wrote: 'The Mendip 

axis divided in the main, but it was breached between Somerset and South 

Wales, so that Dundry had autochthones like Dorset. Dundry was cut off 

from the non-autochthonous area of the Cotswolds by an elevation of the 

Malvern Axis.' Then, to account for the retreat of ammonites towards the 

south in the Upper Inferior Oolite period, he supposed 'the North Devon 

Axis divided'. 1 

This explanation led Buckman to some very extraordinary palaeogeographical 

restorations. Having assumed that communication between the 

Dorset-Somerset area and the Cotswolds was severed, he was faced with 

finding some other connexion between the southern area and the Hebrides, 

where the same ammonites swarmed as in Dorset and Somerset; and he provided 

it by means of a connecting channel round the west of Ireland. 2 On 

this view, w r hich is opposed to all previous palaeogeographical restorations, 

Ireland, Wales, Lyonesse and Brittany were an island, which Buckman named 

Juroceltia. Both to the north-w r est and to the south of it (in the Paris Basin) 

were supposed to be freely-communicating reservoirs of autochthonous 

ammonites, from which the seas over England were supplied; and Buckman 

considered that during the time when the Mendip and Malvern Axes were 

supposed to have prevented communication across England, the drifted 

specimens in the Cotswolds and Midlands came from the northern reservoir, 

via the Hebrides. 

A further difficulty was the presence of relatively numerous and wellpreserved 

ammonites in the Yorkshire Basin in the Stepheoceratan Age 

(during the deposition of the Scarborough Limestone). To account for this 

tectonic theory; the present table contains many amplifications and emendations and the 

tectonic bias is eliminated. 

1 S. S. Buckman, 1922, loc. cit., p. 19. 

2 1922, loc. cit., p. 19; and 1923, map, p. 52.


another sea had to be postulated to the north-east, for in Buckman's view 

communication with the south and west was severed at that time by the 

Market Weighton Axis. 1 

To say the least of these palaeogeographical restorations, they seem extremely 

far-fetched. The Mendip and Malvern Axes, as was shown in Chapter 

III of this book, were probably regions of shallows and interrupted deposition 

and they certainly marked off two well-defined areas—a coralline and a noncoralline 

province—but there is nothing to warrant the supposition that 

throughout their whole length they stood above water, interrupting communication 

completely. There seems no reason to suppose that ammonites could 

not have floated from south to north across parts of the axes visible at the 

present outcrop, and concerning the much wider belt to eastward, hidden 

under the later rocks, there is almost no evidence at all. Deep borings farther 

east might reveal Inferior Oolite transitional between the two types—in fact 

the Westbury boring of 1921 yielded fragments of ammonites which Buckman 

himself identified as probably belonging to the murchisonce zone (p. 200). 

But even if no such rocks were found, this would be no proof of interrupted 

communications; for over the axis region there was probably little deposition 

and there were certainly frequent erosions. It would be as legitimate to base 

a similar assertion on the absence of connecting deposits between the Cole 

Syncline and the Sherborne District. 

Buckman's theory takes no account of the facts that of the lamellibranchs, 

gastropods, brachiopods and echinoderms of the Cotswolds, while a number 

of species are not found in the Dorset and Somerset province (and on these 

emphasis has been laid), yet a much larger number are common to the two 

provinces; and that they constitute an incomparably richer fauna than is 

found in the Hebrides. For these animals, migration via the Hebrides seems 

out of the question. 

If the rest of the fauna was able to migrate across the axes of uplift, we cannot 

suppose that the ammonites were unable to do so. The only conclusion 

seems to be that the ammonites w T ere able to enter the Cotswold province from 

the south, and did so, but that they did not colonize it because it was an uncongenial 

or unsuitable habitat. 

A few that did enter died and were entombed in the rapidly-accumulating 

coral debris of the Cotswold basin; some floated in discites times as far as 

Lincoln, there to become interred in the Silver Bed; but the majority of those 

that crossed the axis passed on until they reached Western Scotland. There 

they found a favourable environment similar to that in the Dorset-Somerset 

area, and in it they settled and became truly autochthonous. The fact that the 

epiboles and faunizones succeed one another in the Hebrides almost exactly 

as in Dorset proves that migration was continuous, and moreover that, as 

Buckman frequently taught, the time taken to perform such a journey was 

negligible in relation to species-duration. Since the rare and non-autochthonous 

individuals in the Cotswolds compose an identical, though incomplete 

and not easily recognized, zonal succession, it seems reasonable to 

regard them as the chance casualties in a non-favourable area, through which 

the species migrated without staying to colonize it. 

In Yorkshire, throughout most of Lower Oolite times, deltaic deposits were 


MEANING OF AMMONITE DISTRIBUTION 565 

accumulating and all forms of marine life, including ammonites, were absent. 

On several occasions, however (pp. 217-22), the deltaic type of deposition was 

temporarily arrested and a marine fauna entered the district, and on the last 

of these occasions—during the Stepheoceratan Age—ammonites tarried in 

fair numbers, their shells becoming embedded in the Scarborough Limestone. 

In the Cotswold and Lincolnshire provinces it was not deltaic conditions 

that produced an inimical or unsuitable environment and prevented colonization 

by ammonites: it was either the concomitants of coral reefs—the heavy 

breakers and strong currents—or else something about the peculiar conditions 

that favoured the growth of coral reefs, but that was repellent to 

ammonites. 

In the Upper Inferior Oolite period (Parkinsonian Age), Buckman notes, 

autochthonous ammonites retreated south from Dundry and most of Somerset, 

at the time when the Mendip Axis and the associated shallows to the 

north (the Malvern Axis?) became submerged. Buckman now shifts the role of 

barrier on to the North Devon Axis; it was this, he says, that in the Parkinsonian 

Age confined ammonites to the Sherborne and Yeovil district and the 

area to the south (as quoted above, p. 563). But if the Mendip and Malvern 

Axes previously prevented ammonites from advancing northward into the 

Cotswolds, as Buckman maintained, why should the breakdown of those axes 

cause the ammonites to retreat still farther to the south ? With the removal of 

the barrier, if there were no other impediment, they might be expected to 

advance northward. Since they did not, Buckman can only have wished us to 

suppose that the North Devon Axis rose above water before the Mendips 

sank, so that the advance of the main body of autochthones was cut off before 

the northern barrier was removed, and then those that had been isolated 

between the tw r o barriers were starved or otherwise extinguished before the 

Mendips sank. 

This elaborate explanation (which Buckman did not put forward, but 

which seems to be necessarily implicit in his hypothesis) does not survive 

examination of the stratigraphy of the North Devon Axis. From the careful 

work of Richardson it is apparent that the Upper Inferior Oolite passes 

across the axis without interruption (p. 236), and the North Devon Axis 

therefore offered no resistance to the free passage of ammonites during the 

Parkinsonian Age. 

Rather it would seem that some force, liberated by the further subsidence 

of the Mendip and Malvern Axes, repelled the ammonites southward at the 

very time when, on Buckman's hypothesis, they should have been free to 

spread northward. It can hardly be mere coincidence that the retreat of the 

ammonites corresponds both in time and in place with the southerly advance 

of corals from the Cotswold province. The spread of the coralline type of 

deposition was in turn probably conditioned by the subsidence of the Mendip 

Axis, which had previously been effective in separating two different basins 

of deposition, but it was only in this indirect manner that the axis influenced 

the ammonites. There is a very great difference between a barrier rising above 

water without a break, in such a way as to bar the passage of floating and 

swimming cephalopods (such as Buckman visualized), and a belt of shallows 

and strong currents, offering no bar to migration, but nevertheless sufficient 

to provide a boundary between two basins which, for some other reason, were

COTSWOLD AREA 

PORTLAND BEDS 

KIMERIDGE 

CLAY 

CORALLIAN BED5 I 

OXFORD 

CLAY 

KELLAWAYS 6ED5 

CORNBRASH 

FOREST MARBLE 

GREAT OOLITE 

LIMESTONES 

FULLER'5 EARTH 

INFERIOR 

OOLITE 

L I AS 

• 400 FT. 

}00 

100 

r 100 

L 0 

PORTLAND STONE 

PORTLAND SAND 

KIMERIDGE 

DORSET-SOMERSET AREA 

CLAY 

CORALLIAN 

BEDS 

OXFORD 

C LAY 

KELLAWAY5 BEDS 

CORNBRASH 

FOREST MARBLE 

FULLER'S 

EARTH 

INFERIOR OOLITE 

LIAS" 1 

FIG. 93. Columns showing the relation between coralline deposits and autochthonous 

ammonites. In left column in each area, dotted = coralline deposits (coralline oolites and 

detrital limestones, &c.); thick dots = coral-beds; cross-hatched = 'Forest Marble' facies. 

In right columns, black denotes autochthonous ammonites.

THE COAST OF ATLANTIS 567 

characterized by different types of sedimentation and different environmental 

conditions. 

Whenever we come to compare the distribution of ammonites and coral 

reefs the interdependence of the two is striking (fig. 93). Where the deltaic 

(or what is generally known as estuarine) type of deposition prevailed, neither 

corals nor ammonites existed; but in the districts w T here other types of deposit 

were being formed, either ammonites were autochthonous or corals, but never 

both. Moreover, at the phase of maximum growth of coral reefs (the Osmington-early 

Glos Oolite periods), when almost the whole of England was 

covered by coral seas, autochthonous ammonites disappeared altogether, 

their scattered shells being only very rarely found even in the areas where 

oolite or debris was accumulating although no actual coral growth was taking 

place (e.g. in South Dorset). The presence of even a few drifted ammonites 

or fragments of ammonites in such deposits, however, precludes their being 

placed in the same category as the Rhaetic and Purbeck Beds, which were 

apparently formed in water definitely cut off by land barriers from all connexion 

with seas inhabited by ammonites, since no trace whatever of cephalopods 

is to be found in them. 

It is just possible that there may be some more subtle reason why corals and 

ammonites should not have flourished in the same waters—perhaps connected 

with the food-supply of the adult ammonites or their free-swimming larvae. 

But since ammonites are extinct, this will always remain a matter of surmise. 

II. PALAEOCARTOGRAPHY 

Whether the resulting conclusions be accepted or rejected, the foregoing 

remarks will at least have served to illustrate the necessity for ecological 

studies as a prelude to attempting palaeocartographical reconstructions. 

Unhampered by the awkward land-barriers or isthmuses which Buckman 

thought it necessary to erect, we may more readily tackle the wider problems: 

the outer boundaries of the Jurassic seas, where they abutted on the ancient 

landmasses, and where they were connected with the continental seas and the 

Tethys. We now enter more deeply into the realms of surmise than at any 

previous stage of this book. 

(a) The General Boundaries of the British Troughs in 

the West and North 

All (with the exception of Buckman) who have attempted to construct 

palaeogeographical maps of the British region in Mesozoic times have agreed 

in one respect, namely, in the existence of a vast landmass, North Atlantis, to 

the west of these islands, over the site of the present Atlantic. Of this landmass 

the last relics are supposed to be the mountains of Wales and the West of 

Ireland, the peninsulas of Devon and Cornwall and Brittany, and perhaps the 

Outer Hebrides. The rest has foundered in the bed of the Atlantic or been 

eaten away by the waves. 

How wide the landmass is likely to have been we do not know; but for all we 

can tell it may have been continuous with the Mesozoic continent which 

Canadian and United States geologists are accustomed to picture as they 

look eastward over the eastern part of North America and the Western


Atlantic—their Jurolaurentia. 1 Further speculations will be idle until the 

Wegener hypothesis that the continents have drifted apart has been either 

proved or disproved. Of more immediate concern is the extent to which the 

Jurassic seas overspread North x\tlantis from the east, and upon this question 

many views have been expressed, supported by many different classes of 

argument. The relevant facts are briefly as follows: 

At the present time three tongues of Jurassic rocks extend more or less intermittently 

westward into the Palaeozoic region and separate the ancient highlands 

of Brittany, Devon and Cornwall, Wales, and Scotland (see fig. 2, 

P. 38): 

(i) The most southerly tongue occupies the site of the English Channel; 

the evidence for it being the dredging up of fragments of Liassic limestone 

30-34 miles south-east and 45 miles south-south-east of the Lizard, 2 and of 

Psiloceras planorbis or an allied species 30 miles south of the Eddystone Lighthouse 

(above, p. 121). 

(ii) The second coincides with the Bristol Channel: it is denoted by the 

westerly extensions of the Lower Lias and Rhaetic Beds in South Glamorgan 

and near Minehead, and these unquestionably extended at one time still 

farther. That there has been Lower Lias in the vicinity of the Gower peninsula 

seems to be indicated by the presence of oysters allied to O. irregularis in 

stalactites in the Carboniferous Limestone at Mumbles near Swansea. 3 

(iii) The northern tongue, by far the most important of all, is denoted by 

the Liassic outliers at Prees in Shropshire (p. 135) and near Carlisle (p. 142), 

by the Lias and Rhaetic Beds preserved beneath the basalt plateau of Antrim 

(pp. 112, 142), and in the Tertiary volcano of Arran (p. 115), and by the disconnected 

but important relics of Jurassic rocks in the Inner Hebrides 

(ranging in age, as we have seen, from Rhaetic to Kimeridgian). A further 

outlier connecting the Shropshire and the Antrim areas is believed, from 

indirect evidence, to exist upon the floor of the Irish Sea, where Mr. E. 

Greenly maps an elliptical area of Jurassic rocks covered by Chalk, as shown 

in fig. 2 (p. 38). The evidence for this is the presence of pieces of a crumbly 

ferruginous oolite like that in thz jurensis and opalinum zones and of 'Jurassiclooking 

boulders, chiefly of calcareous shale' in the Drift on the east side of 

Anglesey, associated with numerous Chalk flints, all of which seem to have 

come from the bed of the Irish Sea to the north-east. 4 Liassic boulders containing 

fossils have also been found in the Drift on the adjoining north coast 

of the mainland, at Penmaenmawr, Carnarvonshire. 5 

Upon the intervening projections of Palaeozoic rocks, the supposed salients 

of Atlantis, there are no traces of Mesozoic sediments, but there are conspicuous 

elevated peneplains at various levels and of uncertain dates. 

The crux of the matter is to decide how far the present arrangement of the 

Jurassic rocks is original: whether they were laid down as they are found, in 

low-lying troughs separated by projecting masses of highland, or whether 

they owe their preservation in those areas to subsequent depression, while 

1 See a series of palaeogeographical maps of N. America by C. H. Crickmay, 1931, 'Jurassic 

History of North America', Proc. Amer. Phil. Soc., vol. lxx, pp. 80-93. 

2 A. J. Jukes-Browne, 1911, Building of the British Isles, 3rd ed., p. 260. 

3 A. E. Trueman, 1922, P.G.A., vol. xxxiii, p. 278. 

4 E. Greenly, 1919, 'Geol. Anglesey', vol. ii, pp. 777-8, Mem. Geol. Surv. 

5 Summ. Prog. Geol. Surv. for 1931, p. 38.

WALES AND THE BRISTOL CHANNEL 569 

erosion has caused the removal of the rest of the strata in the intervening 

areas. Upon this question opinion has always been divided; but it is now 

becoming increasingly probable that neither view is altogether right: that 

some of the high Palaeozoic tracts were submerged and some were not, and 

that often they formed shallows—areas of retarded deposition alternating 

with contemporaneous erosion—rather than dry land. The two schools of 

thought are exemplified by Jukes-Browne and Judd, whose conflicting views 

we will have occasion to examine in the following pages. 

(b) The Boundaries of the Jurassic Sea in Wales and the 

Bristol Channel 

It was a favourite line of reasoning with Jukes-Browne that, although the 

Jurassic formations, if produced, would in places pass over tracts occupied by 

Palaeozoic rocks, the present relief of those tracts is only due to Tertiary and 

Quaternary denudation; therefore that they probably stood a great deal higher 

in Jurassic times, and the Jurassic sea would not have been able to cover them. 

The complementary inference, that if Tertiary and Quaternary denudation has 

been so potent, it has probably destroyed Jurassic rocks that may formerly 

have existed over those self-same areas, received scant consideration. 

Thus Jukes-Browne wrote: 

'This [1,010 ft.] is about the height of the escarpment [on the east side of the 

Forest of Dean] at the present day, and as it must have been very much higher in 

Jurassic times, the sea of the Upper Lias is not likely to have passed over the Forest 

of Dean.' 1 Again: 'We may assume that during the formation of the Lias the coastline 

ran from the eastern border of Dean Forest to Malvern, the gaps which now 

intervene between the higher elevations being due to post-Jurassic erosion. Thence 

it probably trended north-westward through Shropshire and Denbighshire, and 

across the Irish Sea to the west coast of Ireland. . . . From Ireland the sea extended 

over the site of the western Scottish [Keuper] lake, and thence probably up the 

Great Glen to the north-eastern basin.' 2 

For this conservative view there is much to be said, and the distribution 

of land and water outlined by Jukes-Browne in the latter of these passages has 

been generally adopted in text-books and is implicitly accepted by most 

research workers in Jurassic stratigraphy. The great stumbling-block to the 

acceptance of the Malvern and Abberley Hills as the actual shore-line, however, 

has always been the Malvern Fault. This everywhere forms the 

western boundary of the Trias, w r hich it throws down against the Palaeozoic 

and Archaean rocks of Wales. It is hinged in such a way that, although the 

throw is only perhaps 100 ft. near Newnham in the south, it increases to a 

maximum of 1,000 ft. near Malvern. It seems to be entirely post-Triassic, for 

the Trias adjoining it is of the thickness normal for the district and appears 

not to be banked up against it; moreover there seems to be no marginal 

change of facies. From these facts it is inferred that the Trias 'must have 

formerly extended well over the site of the Malvern and Abberley Hills on to 

the area of the Old Red Sandstone'. 3 How far the Trias may have extended 

no one has ventured to calculate; and the question has no certain bearing on 

the former extension of the Jurassic formations, since movement may have 

1 A. J. Jukes-Browne, 1911, loc. cit., p. 265. 

3 T. Groom, 1910, Geol. in the Field, pp. 717 and 726. 

2 Ibid., p. 266.


begun along the fault immediately after the end of Triassic times. As we have 

seen, the Rhastic Beds of the Berrow Hill outlier and the western side of the 

Worcestershire outcrop, as w r ell as the Inferior Oolite of the Cotswolds, show 

signs of a shore-line at no great distance (p. 108). It would not be surprising 

if the fault were a marginal fracture caused by unequal subsidence of the 

Jurassic trough, for it adjoins the deepest part of the trough, where the Lias 

and the Lower Oolites attain thicknesses far exceeding any developed in other 

parts of the South of England. 

A reasoned attempt to ascertain to what extent the Mesozoic rocks, especially 

the Trias, may have encroached upon the Palaeozoic tract of Wales was 

made by Prof. O. T. Jones in 1930, in the course of a suggestive study of the 

Bristol Channel region. 1 His most important innovation is an endeavour to 

trace Tertiary folding from the Mesozoic region on the east into the Palaeozoic 

tract of the west, and he comes to some novel conclusions. He believes 

that Central and North Wales have been uplifted by a broad anticlinal axis 

extending east and west, probably a prolongation of that which gave rise to the 

major deflexion of the Chalk outcrop and strike in Fenland. Similarly, he 

considers the high elevation of Exmoor to be due, not so much to the superior 

hardness of the rocks of which it is composed, as to its being on the axis of 

uplift between the syncline of Central Devon and another centred along the 

Bristol Channel. The Bristol Channel he considers to be a broad E.-W. 

Miocene downfold, analogous with the syncline of the London Basin, but 

resembling it as a mirror image and pitching to the west. 

These conclusions are reached along two lines of reasoning. The first is the 

drainage. As Strahan pointed out, 2 the rivers of South Wales bear no relation 

to the structures resulting from the Armorican and Charnian orogenic movements, 

but disregard them entirely, cutting through the highest escarpments 

by deep gorges. South Wales has, in fact, a superimposed drainage, which can 

only be explained by supposing it to have originated upon a blanket of Mesozoic 

strata sloping gently south-eastward, but now entirely removed. Strahan 

supposed that this blanket was composed of sediments of Upper Cretaceous 

date—an idea which was acclaimed by Jukes-Browne, for it fitted in with his 

view of the former wide extension of the Upper Chalk sea over all except the 

highest districts of North and Central Wales and the Brecon Beacons. 3 Quite 

apart from the question whether the sedimentary blanket was composed of 

Jurassic or Cretaceous strata, Strahan's theory, if correct, is held to involve a 

post-Cretaceous (presumably Miocene) uplift of North Wales relative to 

South Wales. Actually, however, it is conceivable that the drainage may have 

started upon an original slope of deposition, and so it does not seem absolutely 

necessary to invoke tilting. 

The other line of reasoning by which Prof. Jones was led to the belief in a 

Miocene uplift of North Wales was a consideration of the slope of the sub- 

Mesozoic platform when traced beyond the region where Mesozoic deposits 

remain upon it. This subject is of such importance that we will proceed to 

a short independent examination of the data; for Prof. Jones considers it 

legitimate to assume that marine Rhaetic and Liassic (if not later) strata were 

1 O. T. Jones, 1931, Rept. Brit. Assoc. for 1930, Presid. Add. Sect. C, pp. 57-82. 

2 A. Strahan, 1902, Q.J.G.Svol. lviii, pp. 207-25. 

3 A. J. Jukes-Browne, 1911, loc. cit., fig. 53, and p. 335.


deposited, not only over all parts of the platform where Trias is now found, 

but also over all those parts from which it has been removed by subsequent 

erosion. 1 But apart from this assumption being invalidated by the existence 

of a fault such as that at Malvern, which although post-Triassic, may be pre- 

Jurassic or at least intra-Jurassic, it is important that there should be absolute 

certainty that the sub-Mesozoic platform can be correctly identified. It is 

therefore to the identification of the platform that we will pay special attention. 

Within the British Isles the ideal district for studying the sub-Mesozoic 

platform where it first begins to emerge from beneath its sedimentary covering 

is the area surrounding the head of the Bristol Channel, in Somerset, Monmouth 

and Glamorgan. Here recent denudation has so far stripped off the 

covering that it is possible to obtain a clear idea of the surface that lies beneath, 

while at the same time a sufficient amount remains still buried to leave no 

doubt as to the age of the feature. 

A more or less unevenly sculptured surface of Palaeozoic rocks lies revealed, 

evidently an old landscape, formed by the wearing down of the Armorican 

mountains under subaerial agencies—probably in a desert climate. All the 

original tectonic features had been planed down, so that the Triassic deposits 

overstep rapidly across the basset edges of the various Palaeozoic formations; 

and in places, such as near Cardiff, where the Keuper rests on Silurian, at 

least 7,000-8,000 ft. of Upper Palaeozoic rocks were removed. Here and 

there, however, residual hills or 'monadnocks' were left standing above the 

general level of the undulating plain, and later these formed islands, first in the 

Keuper lake and then in the Rhaetic and Liassic seas (as described on pp. 103- 

5 above). The most important of the smaller monadnocks were the Mendips, 

Quantocks, and Cowbridge Island (see fig. 17, p. 104). Beyond these the 

scarp of the South Wales Coalfield certainly rose to even higher elevations; 

but whether it merely formed the edge of a much larger manadnock, or was 

the fringe of a great tract of ground lying to westward at a higher level 

and worthy of the name of mainland, usually bestowed upon it, is a difficult 

problem. 

The configuration of the sub-Mesozoic platform in the Bristol Channel 

district and the gradual submergence of the monadnocks by the marine 

transgressions of the Rhaetic and Lias have been vividly described in the 

following passage by Strahan, 2 who elucidated the sequence of events in 

Glamorgan: 

'The features of the old landscape were due primarily to the effects of denudation 

upon the sharply folded Palaeozoic rocks. Then, as now, the Carboniferous Limestone 

formed scarps and the Old Red Sandstone stood up as rounded hills. Around 

and between these features the marl was spread out, mixed at its margin with the 

debris that fell from their sides. As the subsidence continued the marl and breccias 

extended further up the slopes, but, though they had covered the small crags, they 

had failed to surmount the higher tracts when they were succeeded by the Tea 

Green Marls. Gradually diminishing in size, these same tracts can be easily recognized 

through the period of the Tea Green Marls, of the Rhaetic, and of part of the 

Lias, but they all finally disappeared during the deposition of the Lower Lias.' 

It might be thought that such a well-marked peneplain, with its residual 

monadnocks, would be easy to follow over wide areas in other parts of Britain. 

1 O. T. Jones, 1931, loc. cit., p. 64. 

2 A. Strahan, 1904, 'Geol. South Wales Coalfield, Part VI, Bridgend', p. 22,Mem. Geol. Surv*


But directly we leave the fringe of the surviving Triassic deposits we are 

faced with two difficulties: (i) uncertainty (or, rather, complete ignorance) 

of the level at which to look for it, and (ii) interference by other peneplains of 

much later date. 

The first difficulty will be readily appreciated by considering the differences 

in level of the sub-Mesozoic peneplain or Palaeozoic platform beneath those 

parts of England that are still under the Mesozoic covering. As pointed out 

in Chapter II, it has been continually depressed beneath the Jurassic troughs 

of deposition, and to an increasing extent towards the centres of those troughs, 

throughout the Jurassic period; and as remarked on p. 50, it may have been 

still further depressed in the same places by the very Miocene movements 

that gave rise to anticlines in the Chalk covering above (for example under the 

Weald). The Palaeozoic platform is tw T o or three thousand feet lower under 

Hampshire and Sussex than in Somerset, where it comes to the surface (see 

figs. 3-6). It plunges rapidly below sea-level again beneath the Bristol Channel. 

At what level, therefore, are we to look for it over Wales, and so how is it to be 

distinguished from other peneplains ? 

This brings us to the second difficulty. The sub-Mesozoic peneplain has 

been identified with the 400-ft. coastal platform of Carmarthen and Pembrokeshire. 

No Mesozoic strata are found in situ so far west, but the presence of red 

marls of Triassic appearance in gash-breccias, or the filling of collapsed caverns 

in the Carboniferous Limestone, and the local red staining of the limestone, 

have been taken to indicate the former presence of the Trias. Prof. Jones 

therefore suggests that the conspicuous monadnocks, such as the Prescelly 

Mountains and Cam Llidi and others, which dominate the Pembroke peninsula, 

are survivals of the Triassic landscape just as are those in Glamorgan and 

Somerset; in fact, that the coastal plain of Pembrokeshire is substantially the 

sub-Mesozoic peneplain. 1 Mr. E. E. L. Dixon, who has studied the peninsula 

in detail, also considers that 'though the Triassic floor has undergone some 

later planation, this has merely touched up the work of the earlier erosion'. 

Nevertheless he admits that 'parts of it show little trace of Triassic staining 

and none [shows any trace] of Triassic deposits; on the contrary it supports 

relics of post-Triassic sediments': 2 'as though the surface of the original 

Triassic landscape had been considerably pared down', as he wrote a few years 

earlier. 3 

This coastal platform compares perfectly, in fact, with the Pliocene platform 

of Cornwall. From the Cornish platform rise the monadnocks of Carn 

Menellis, Carn Brea, Carn Marth, St. Agnes' Beacon, &c., for all the world 

like Carn Llidi and its companions across the Bristol Channel; and upon its 

surface, as proof of its age, lie the relict patches of Pliocene deposits at 

St. Erth and St. Agnes. There are upon parts of the Pembrokeshire platform 

also the same type of gravels as in Cornwall, probably dating from the 

slightly earlier period at which the peneplain began to be formed by subaerial 

agencies. In one place, too, not far from Pembroke, is a considerable patch 

of pipe-clay of uncertain Upper Tertiary age, and at least 45 ft. thick. 4 

1 O. T. Jones, 1931, loc. cit., pp. 62-4. 

2 E. E. L. Dixon, 1921, 'Geol. South Wales Coalfield, Part XIII, Pembroke and Tenby', 

p. 162, Mem. Geol. Surv, 

3 E. E. L. Dixon, 1914, 'Geol. South Wales Coalfield, Part XI, Haverfordwest', p. 199, 


4 E. E. L. Dixon, 1921, loc. cit., pp. 166 et seq.


The Pliocene coastal platform occurs also in North Wales and Anglesey, 

varying within a hundred feet or more in height, and often separable into two 

or more stages. In Anglesey and the adjoining mainland Greenly has described 

three such platforms, at 550 ft., 430 ft., and 275 ft., all of which he considers 

probably of approximately Pliocene date; and since the highest has monadnocks 

rising out of it as in Pembroke and Cornwall, he calls it the Monadnocks 

Platform. 1 The point of interest about these platforms in our present context 

is not their precise heights, but their late Tertiary (conveniently generalized 

as Pliocene) date, and their widespread distribution. They enable it to be said 

with confidence that the existence of a platform at about 400 ft. with monadnocks 

in Pembrokeshire, even though there may be some places farther east 

along the coast where it coincides with the sub-Mesozoic peneplain, is no 

proof of the former existence of the Mesozoic base at anything like that level 

over the Pembrokeshire peninsula. The point is one of some importance, for 

if the Mesozoic base did extend at so low a level across the peninsula, it would 

seem to be shaping to pass round behind the highlands of Wales. 

The question is precisely similar to that arising in the promontory formed 

farther north by the Isle of Anglesey. Near at hand under the Irish Sea, as 

under the Bristol Channel, the base of the Trias is well below sea-level (p. 568 

and fig. 2, p. 38). The adjoining land is peneplaned, and from the peneplain 

rise monadnocks. But Greenly does not attribute the peneplain and the 

monadnocks to the Trias. Although he asserts that 'it is, of course, evident 

that the Mesozoic rocks must have extended over the tract that is now the 

Isle of Anglesey', he considers that the Mesozoic base over the island was 

probably more than 700 ft. above sea-level. 2 

Prof. Jones has endeavoured to trace the sub-Mesozoic peneplain farther 

into Central Wales. He describes how in North Pembrokeshire, Carmarthenshire 

and South Cardiganshire the coastal plateau at 400 ft. slopes upward 

inland and merges imperceptibly into the high plateau of Central and North 

Wales, at 1,900 or 2,000 ft. 3 The high plateau was noticed as early as 1846 by 

Ramsay (who attributed it, however, to marine erosion) 4 and it has been 

described also by Prof. Fearnsides 5 and others. It is a well-marked feature 

from which the highest mountains of the Snowdon group, Cader Idris, the 

Arenigs and Arans, Plynlimon, &c., stand out as monadnocks, like those on 

the lower plateau. Prof. Fearnsides also spoke of it as 'sloping gently away 

to the south-east across Merioneth and Cardiganshire', and Prof. Jones in an 

earlier paper described how it 'extends to the foot of the Upper Old Red 

Sandstone escarpment of Breconshire and Carmarthenshire, which overlooks 

it as a line of high cliffs overlooks a level foreshore'. 6 The continuous slope 

of the platform is taken by Prof. Jones to indicate that the whole of it is the 

sub-Mesozoic peneplain which has been warped up in Central Wales, as 

explained on p. 570. The logical conclusion at which he arrives is that 'it 

would be rash to assert that the Lias did not extend over the Palaeozoic 

1 E. Greenly, 1919, 'Geol. Anglesey', vol. ii, p. 783, Mem. Geol. Surv.; see also W. G. 

Fearnsides, 1916, Q.J.G.Svol. lxxii, p. 76 (platforms in Carnarvonshire). 

2 E. Greenly, 1919, loc. cit., p. 778. 

3 O. T. Jones, 1931, loc. cit. 

4 A. Ramsay, 1846, Mem. Geol. Surv.y vol. i, pp. 331, 333 ; and 1866, ibid., vol. iii, p. 236. 

5 W. G. Fearnsides, 1910, Geol. in the Field, pp. 820-1. 

6 O. T. Jones, 1924, Q.J.G.S., vol. Ixxx, p. 568. 

854371 

r r


area of Wales and the Welsh Borders; the formation may, indeed, have 

attained a thickness of several hundred feet over that area'. 1 

Before accepting so far-reaching a conclusion as this it is well to examine for 

comparison the ancient Palaeozoic tract under London, which, as already 

remarked (p. 52), offers unique opportunities for studying the relations of the 

Mesozoic rocks to the platform. Here all the evidence has been preserved and 

can be studied by means of borings, whereas around the western and northern 

landmasses the critical strata have been completely destroyed by erosion. 

The first fact to strike the eye on referring to Lamplugh's sections is that, 

although the surface of the platform has a continuous slope, it is not all of the 

same age, in the sense that neither Trias nor Lias nor any other single formation 

of the Jurassic stretches or apparently ever stretched all over it. Owing 

to the peculiar combination of oversteps and overlaps occurring at the margins 

of the trough of deposition (as shown in fig. 91, p. 544) progressively later 

rocks transgress on to it at progressively higher levels. Therefore, although 

the lower part of the peneplain may have lain beneath the Liassic water-level, 

the higher parts were not inundated until the Upper Cretaceous. Yet, if the 

Mesozoic rocks were to be stripped entirely away, the peneplain would presumably 

look much the same as that of Wales. The points that must be 

emphasized are (1) that the slope of the peneplain was not imposed upon it 

by the Miocene earth-movement, but was slowly acquired, stage by stage, 

through the subsidence of the Jurassic trough around it; and (2) that the landarea 

was exposed to prolonged subaerial denudation, the highest parts for the 

longest time, before finally sinking beneath the sea and perhaps having a 

submarine peneplain superimposed upon the subaerial one. 

By analogy, it is not unreasonable to suppose that by the end of Jurassic 

times the slope of Palaeozoic rocks in Central Wales was already tilted southward 

and eastward so steeply that, if there has been any Miocene uplift, its 

effects have been relatively trivial. 2 

The Miocene uplift of Exmoor, which, as Prof. Jones points out, produced 

a water-parting from which the streams flow southward into the syncline of 

Central Devon and northward into that of the Bristol Channel, was merely 

a revival of an earlier uplift. Prof. Jones calls Exmoor an analogue of the 

Wealden anticlinorium and the Bristol Channel an analogue of the London 

Basin synclinorium.3 The Miocene movements, which conditioned the 

modern drainage, may, it is true, have had similar effects in the two areas; 

but it is the fundamental structure that concerns us here, and in this there is 

no analogy. Exmoor, as we saw in Chapter III (pp. 71-3), lies upon the 

North Devon Axis of uplift, which was a line of retarded deposition, indicating 

non-subsidence or relative elevation, in the Jurassic period. The Weald, on 

the contrary, was a region of depression and heavy sedimentation throughout 

the Jurassic period. Further, the Bristol Channel, as is shown by the surviving 

outcrops of Lias, was depressed early in Jurassic history, while the 

London Basin probably remained above water j[or most of the Jurassic period 

—at least it is the very region where the Palaeozoic platform rises nearest the 

surface and attains its maximum convexity. So far from being analogous, 

1 O. T. Jones, 1931, loc. cit., p. 66. 

2 I say 'if' because the drainage may have been initiated upon an original slope of deposition 

of the Cretaceous covering, 

3 O. T. Jones, 1931, loc. cit., p. 81.

EXMOOR CONTRASTED WITH THE WEALD 575 

therefore, the Weald and Exmoor, in their fundamental structure, are opposites. 

Yet both appear to have been elevated during the Miocene orogeny, 

while both the London Basin and the Bristol Channel, equally opposite, were 

depressed. 

This is only one of several instances illustrating the apparent contradiction 

between Godwin-Austen's 'law' (p. 59) that the Miocene anticlines arose 

along the lines of earlier anticlines, traceable in the Jurassic and earlier rocks, 

and Lamplugh's 'law' (p. 47) that the greatest uplifts that occurred in the 

Miocene period were superimposed upon broad synclines in the Jurassic 

rocks beneath. At first sight the contradiction is puzzling, and seems to render 

both laws worthless. But the explanation is, I think, that Godwin-Austen and 

Lamplugh made their observations on two different types of uplift, both of 

Miocene date, but arising upon different foundations from different immediate 

causes (though both were due ultimately to pressure); and so both laws are true 

when applied to the type of phenomenon from which they were first deduced. 

Godwin-Austen had in mind the type of anticline exemplified by the Vale of 

Pewsey and the Hog's Back—a long but relatively narrow fold or ripple in the 

strata, often consisting of strings of periclines. Such folds, of which the eastwest 

axes are the best examples, are all based upon older folds of Armorican 

date, and their Miocene revival was only the last of many revivals of activity 

spanning all Mesozoic time (see Chapter III). 

Lamplugh, on the other hand, studied the Weald, which is not a single 

anticline but an anticlinorium. Folds which replace those of the Vales of 

Pewsey and Wardour eastward pass on over the Wealden anticlinorium merely 

as ripples upon its surface. It is not one of the separate anticlines that is based 

upon a syncline, but the whole anticlinorium that is based upon a synclinorium 

in the Jurassic rocks underneath; and the synclinorium is the Jurassic trough 

of deposition. The supposed cause of the upfold of the Cretaceous rocks 

here, by compression of the Jurassic trough already filled with sediment, was 

explained on p. 50. 

It so happens that in the Weald the Jurassic trough coincides in direction 

with the east-w T est or Armorican folds. But elsewhere (fig. 7, p. 48) the folds 

cut across it at all angles, and so give rise to 'axes of uplift' across the troughs. 

The Mendip and the North Devon Axes intersect the trough of deposition 

in Somerset and Wilts, roughly at right-angles (see map, fig. 15, p. 86). Therefore 

the elevations along these axes acted at right-angles to the broader 

bulging up of the Chalk over the deepest parts of the trough. But over the 

axes the trough was shallow and there was correspondingly little bulging up; 

therefore an anticline of east-west directrix was always the dominant result 

of the Miocene earth-pressures over the ancient axes of uplift, no matter what 

the direction of the trough thereabouts might be. 

The bearing of this upon our present problem will be obvious. It explains 

why the uplift of the North Devon Axis was dominant, although the trough 

of deposition crossed it at right angles, and therefore how the east-west elevation 

of Exmoor came to condition the drainage, rather than any bulging up of 

the Cretaceous rocks over the Jurassic trough in a contrary direction. In this 

way came about the analogy between the drainage of Exmoor and that of the 

Weald,which proves so deceptive when used as the starting-point for inquiries 

into the tectonic history of Mesozoic times.


To summarize the conclusions to which a study of the ancient landmass 

under London leads us: 

(1) The surface of the London landmass is a peneplain, which slopes gently 

under the Mesozoic covering. The covering is still intact owing to its having 

been carried for the most part below the reach of the forces of erosion by the 

south-easterly tilt to which the British Isles were subjected early in the 

Tertiary period. On the other side of the Jurassic trough the Welsh highlands 

rise similarly with a peneplaned surface, but they have been stripped bare in 

the Tertiary and Quaternary periods. 

(2) If, as seems probable, the two landmasses on opposite sides of the Jurassic 

trough were analogous, none of the Triassic or Jurassic rocks is likely to 

have passed right over the top of the Welsh highland, although they may have 

encroached to an unknown extent round its margins, beyond their present 

outcrop. 

(3) The slope of the Welsh peneplain was not acquired as the result of the 

Miocene orogeny, although it is possible that it was steepened at that time. 

The surface sagged gradually throughout the Jurassic period as the trough 

subsided. It is probable that the south-easterly slope would be considerably 

greater had not the stresses found relief in the Malvern Fault, whereby the 

subsidence of the trough was probably enabled to continue without dragging 

the margin of the adjoining highland with it. 

(4) The depression of the Bristol Channel, where Trias and Lias still exist 

below present sea-level, represents a branch of the Jurassic trough of deposition, 

analogous with the Kentish Weald. The floors of these depressions 

sagged to their present low relative levels during the Jurassic period, not as the 

result of the Miocene folding. 

(5) The highland of Exmoor lies upon an Armorican anticline, along which 

activity was repeatedly revived during the Mesozoic period, when it and its 

continuation eastward formed the North Devon Axis of uplift, crossing the 

Jurassic trough of deposition at right-angles. It was finally re-elevated during 

the Miocene orogeny, and this revival gave rise to the Vale of Wardour fold 

and initiated the present drainage of Exmoor. 

(c) The Dartmoor Highland 

Concerning the elevation of the Dartmoor highland in the Mesozoic 

period an altogether new line of inquiry has been opened up by the study of the 

mineral assemblage of the Dartmoor granite. Dr. A. W. Groves has carried 

out a series of investigations in the sediments of all ages in the South of 

England with the express object of detecting the earliest appearance of this 

assemblage of heavy minerals. 1 

Assuming that the batholith was intruded in Permo-Carboniferous times, 

and that its granitic structure proves it to have crystallized slowly under a 

thick covering (probably 5,000 ft.) of Palaeozoic rocks, the problem was 

to find at what period the covering first began to be removed so far as to expose 

the granite. Dr. Groves finds that the sought-for detritals first appear in the 

Wealden Beds, while the many Triassic and Jurassic sands contain not a trace. 

The inference is, therefore, that throughout Triassic and Jurassic times the 

1 A. W. Groves, 1931, 'The Unroofing of the Dartmoor Granite*, Q.J.G.Svol. lxxxvii, 

pp.62-96.

THE DARTMOOR HIGHLAND 577 

Dartmoor highlands were some thousands of feet higher than at present, 

relative to the sub-Mesozoic floor, the granite still lying buried beneath its 

covering of Palaeozoic strata and remaining untouched by denudation until 

the period of the Wealden lakes. This seems to vindicate Jukes-Browne's 

line of reasoning that the Palaeozoic land areas were much higher in the Jurassic 

period than now. 

Striking evidence is available of the height and steepness of the mountain 

tract of Dartmoor during the formation of the earlier New Red rocks. The 

Triassic peneplain in Devonshire comes to an end abruptly against the high 

ground in a manner suggestive of its termination against the escarpment of 

the South Wales Coalfield. Beyond, buried valleys, filled with New Red 

rocks, run for considerable distances westward into the folded Carboniferous 

tract, out of which they were carved during the Epiric or New Red 

continental period. Although their excavation would date from an earlier 

stage of the erosion of the Armorican mountains than the formation of the 

desert peneplain of the Trias, the fact that they were not destroyed by the production 

of the peneplain testifies to the survival of high ground into the 

Jurassic period. The steep gradient of the valleys is remarkable. In the 

largest, which runs from Exeter westwards through Crediton to Hatherleigh, 

the floor lies more than 2,000 ft. lower than the top of the Dartmoor granite 

only 4 miles away; yet apparently erosion in the upper course of the valley had 

not reached the granite, for no detritus from it is found in the New Red filling 

below. 1 

In dealing with Wales we are hampered by the fact that not only has all 

trace of Jurassic rocks been swept away from the neighbourhood of the existing 

high ground, but all trace of the Cretaceous rocks also. It is therefore particularly 

instructive that in Devonshire, in one restricted area, we are afforded an 

opportunity of observing the relations of Cretaceous and Eocene strata to the 

Palaeozoics, within a few miles of the highland of Dartmoor. 

The Upper Cretaceous rocks of the Blackdown Hills and the dissected 

plateau to the south, which themselves project many miles farther west than 

any other Cretaceous outcrops in England, are continued after a gap of about 

15 miles by the diminutive outliers of the Haldon Hills, south of Exeter. Already 

at Seaton on the coast the cliff-sections show the Albian overstepping 

the Lias and Rhaetic Beds and coming to rest on the Keuper Marls, and the 

discordance can be followed in the cliffs as far as the Peak Hills west of Sidmouth. 

The inland outcrops continue the overstep until on the Haldon Hills 

the Albian rests upon the Permian. But there is also an overlap within the 

Albian, for the lower part of the Upper Gault (in the arenaceous facies known 

as Blackdown Beds), present in the Blackdown Hills, is absent at Haldon. 

'Not only is there this overlap westward, but the sands at Haldon have become in 

places coarse-grained, granitic, or even pebbly. The fauna they yield is also highly 

suggestive of shoal water, or even of a shore-line within a few miles. Compound 

corals resembling littoral forms, absent from Blackdown, are here abundant and 

varied; the mollusca are thick-shelled strong species, such as could stand much 

knocking about.' 2 

Within 3 miles to the west, in fact, is the present edge of the Dartmoor 

1 A. W. Groves, 1931, loc. cit., p. 69. 

2 C. Reid, 1913, 'Geol. Newton Abbot', p. 93, Mem. Geol. Surv.


granite, beyond which heights rise rapidly to 1,200 ft. and 1,500 ft. above sealevel, 

and eventually to about 2,000 ft. on the highest points of the moor. 

Since the base of the Cretaceous rocks on Haldon is only about 700-50 ft. 

above sea-level and there is no sign of folding or faulting on a comparable 

scale, it is evident that they abutted against a shore-line somewhere in the 

next few miles to the west, where a deep valley has since been excavated by 

the River Teign. The total thickness of the Albian rocks is about 65 ft. on 

Great Haldon and 90 ft. on Little Haldon. Upon them lies a sheet of gravel of 

presumably Eocene age, composed mainly of Chalk flints mixed with finergrained 

detritus from Dartmoor. The fossils in the flints indicate the former 

existence of nearly all the zones of the English Chalk. 

If a section be drawn from Dartmoor through the Haldon Hills to the main 

Mesozoic outcrop of Dorset, filling in the gaps caused by subsequent erosion 

(fig. 94), certain marked resemblances to the section through the eastern 

margin of the Mesozoic trough emerge. In the first place the Cretaceous 

rocks appear as a transgressive sheet, overstepping the Jurassic and Triassic 

strata outwards; secondly, the Cretaceous rocks show overlap within the series, 

the higher overlapping the lower. This is in principle exactly what occurs on 

the margin of the London landmass. But there are important differences. 

The principal are, that in Devon (1) the New Red rocks are vastly thicker and 

are not overlapped by the Jurassics before those are in turn overstepped by the 

Cretaceous; and (2) the Cretaceous oversteps regularly on to progressively 

older members of the Jurassic System westward, the last being the Lower 

Lias and Rhaetic; whereas against the London landmass it jumps from Lower 

Oolites on to Palaeozoics, the Lias having been previously overlapped and 

overstepped by the Oolites (see fig. 8, p. 52). The second difference is 

accounted for by the fact that the Cretaceous overstep against Dartmoor is 

considerably steeper (previous tilting was greater) than against the London 

landmass, so that the edges of the higher Jurassic formations, which may 

once have spread beyond the boundaries of the Lias, would have been 

removed prior to the Cretaceous transgression (this is suggested diagrammatically 

in fig. 94). A comparison between the feather-edges of the Jurassic 

rocks in Devonshire with those around the London landmass is therefore 

legitimate. We may presume that a similar combination of overlaps and 

oversteps and paucity of sedimentation within the Jurassic Series took place 

towards the shore-line of Dartmoor, but we must imagine all the evidence as 

having lain at some unknown (but probably not very great) height above 

the present plane of discordance at the base of the Cretaceous. The marked 

westerly attenuation of the Green Ammonite Beds of the Lower Lias between 

Golden Cap and Black Ven may be significant in this connexion (p. 119). 

The alternative explanation to the one here offered, namely that the Jurassic 

System (some 3,000 ft. thick in Dorset), or at least a substantial part of it, was 

laid down over the top of the Dartmoor highland, but has since been removed 

owing to Tertiary uplift of the highland, as Prof. Jones would have us believe 

of Wales and Exmoor, is here discountenanced by the existence of the Albian 

patches on the Haldon Hills. These patches prove that the necessary uplift 

and erosion must have taken place before the Albian period instead of in 

the Miocene as postulated for Wales and Exmoor; and although there certainly 

was pre-Albian and post-Jurassic uplift of the landmass relative to

THE DARTMOOR HIGHLAND 

the adjoining trough, such colossal 

upheaval and stupendous erosion be- ^ 

tween the Jurassic and Cretaceous 

periods as would be required on this 

view seems altogether improbable. 

Incidentally the low level of the 

Haldon Cretaceous and Eocene outliers 

relative to the adjacent granite 

mass throws interesting light on the 

age of the erosion features on the top 

of Dartmoor. If the granite was not 

submerged by the Cretaceous sea, it 

has been undergoing subaerial denudation 

for a very long period. Any one 

who is acquainted with the vast sheets 

of fresh and coarse granitic detritus, 

largely of Dartmoor origin, spread out 

over the Dorset-Hampshire Basin and 

constituting the Bagshot Beds, will 

readily ascribe the main roughing out 

of the existing features on the highest 

part of the moor to the Eocene period. 

Hence if there is anything in the suggestion 

of Travis 1 that the highest 

points on Dartmoor 2 and Exmoor 3 are 

part of a subaerial peneplain and continuous 

with the 1,900-2,000 ft. plain 

of North and Central Wales, sloping 

towards a base-level of erosion to the 

south or south-east, then the Eocene 

is at least a likely period for the formation 

of this peneplain. The Eocene 

gravels, granitic sand and pipe-clay of 

the Dorset and Hampshire heaths can 

only have reached their present positions 

across a continuous sheet of 

Chalk, stretching up to the flanks of 

Dartmoor over the sites of the modern 

valleys of the Teign, Exe and Otter. 

It is highly probable, and in accordance 

with Jukes-Browne's restoration 

of the Chalk sea, that the highest parts 

of the peneplain in North Wales, 

with the largest monadnocks rising 

from it, may likewise never have been 

submerged beneath any Mesozoic sea 

1 C. B. Travis, 1914, Pres. Add. Liverpool 

Geol. Soc., vol. xii, p. 26. 

2 High Willhays, 2039 ft.; Cut Hill, 1981 ft. 

1,908 ft. 

; White Horse Hill, 1,974 ft-J Lints Tor » 

3 Dunkery Beacon, 1,707 ft.

580 PALAEOGEOGRAPHY 

but may have been still undergoing subaerial erosion in the Eocene, when 

the Mesozoic rocks themselves formed the continuation of the same plain to 

eastward. This seems to have been the view of Prof. Fearnsides, who was the 

first in modern times to give a description of the feature in North Wales; he 

wrote: 'As to the age of the peneplain we have no evidence. . . . Probably 

it is an early Tertiary surface of subaerial denudation which, reduced to a 

condition of low relief, had its drainage rejuvenated by the further uplift of 

the Miocene/ 1 

(d) The Pennine Range and the Lake District 

In considering the question of the possible extension of the Jurassic sea over 

the high Palaeozoic tracts of the North of England, and in particular the 

Pennine Range and the mountains of the Lake District, there are two lines 

of approach: (i) direct internal evidence for or against land to the west or 

north-west in the Jurassic sediments of Leicestershire and Lincolnshire, the 

Yorkshire Basin, and the Carlisle outlier; (2) evidence bearing on the date 

of upheaval of the high features beyond the present confines of the Jurassic 

outcrop, so that it may be judged whether it is probable that the Jurassic sea 

ever overspread them. These two classes of data will now be briefly considered. 

INTERNAL EVIDENCE OF PROXIMITY TO LAND IN THE JURASSIC ROCKS OF 

NORTHERN ENGLAND AND THE MIDLANDS 

Until very recently the microscope was not used for examining the sands of 

the Yorkshire Jurassic, and the data considered in inferring their source of 

origin were entirely macroscopic—false-bedding, thickening and increase in 

coarseness. On these grounds it was generally believed that the materials of 

the thick deltaic deposits of the Middle and Upper Jurassic were brought 

into Yorkshire from the north, or from rather west of north. Eighty years ago 

Sorby came to the conclusion, on taking the average of a large number of 

measurements, that the false-bedding indicates currents from about WNW., 2 

and more recently Mr. Black has ascertained that the washout channels also 

indicate a flow of water from north to south (p. 315). As a whole the 'Estuarine 

Series' thickens towards the north of the Yorkshire Basin and, as Fox-Strangways 

pointed out, the sand-grains become coarser towards the west, thus 

suggesting a source of supply in the north-west. 3 

Most of the other Jurassic formations of the Yorkshire Basin were considered 

by Fox-Strangways to show signs of having been formed off land 

lying in approximately the same direction, ranging from north to west, on 

account of their either thickening in that direction or becoming more arenaceous, 

or both. Thus the Middle Lias changes in facies towards the northwest 

from a deeper-water argillaceous deposit to a series of calcareo-arenaceous 

ironstones (pp. 160-1), suggesting to Fox-Strangways that land lay not far 

north-west of Eston Moor near Middlesborough. 4 The Scarborough Beds 

or Grey Limestone Series likewise become excessively coarse and arenaceous 

at Eston Moor, so that Fox-Strangways says: 'It is therefore probable that 

1 W. G. Fearnsides, 1910, Geol. in the Field, p. 821. 

2 H. C. Sorby, 1852, Proc. Yorks. Phil. Soc., vol. i, pp. 111-13. 

3 C. Fox-Strangways, 1892, J.R.B., p. 391. 4 Ibid., pp. 387, 389.

THE PENNINES AND THE LAKE DISTRICT 581 

a shore-line existed somewhere to the west, and not far from the present 

north-west outcrop; arenaceous beds were formed in the west, while calcareoargillaceous 

strata were deposited in the east/ 1 The Kellaways Beds thicken 

in general towards the north, like the Estuarine Series, the constituents of 

which the sands resemble; and Fox-Strangways considers this 'incontestable 

proof that the sandy sediment must have been derived from the north'. 2 

Mere increase of thickness, however, is no proof of approach towards a shoreline, 

since it may be caused by thinning in the opposite direction against an 

axis of uplift, where sedimentation was retarded. Fox-Strangways himself 

records on the next page that the Oxford Clay thickens to a maximum in the 

south-east, but he does not infer from this that land lay in that direction, but 

rather the deepest part of the sea, while uplift was going on in the north-west. 

The lenticular shape of the Hambleton Oolite Series and the westerly thickening 

of the Middle Calcareous Grit were likewise taken by the same author to 

indicate land in the west, and he suggested that the sub-oolitic limestone of the 

Hambleton Oolite might be composed of detritus from a coral reef 'extending 

along the flank of the old Palaeozoic land to the west, which we have every 

reason for believing existed during the whole of the period'. 3 Hudleston was 

equally convinced that land existed not far to the north-west of the Yorkshire 

Basin in the Oxfordian period. 4 

We cannot accuse Fox-Strangways of being biased and of interpreting all 

evidence in favour of a preconceived notion that there was land to the north 

and west; for he records of one formation—the Dogger—that a more calcareous 

development along the western escarpment seems to him to indicate 

'somewhat deeper water' in that direction, and he is led to suggest that the 

channels of the Dogger (p. 224) may be 'a series of narrow inlets connected 

with a larger sea to the west'. 5 He makes no comment, however, on the inconsistency 

of this with the evidence derived from the other formations, and 

the reader is left to reconcile the opinions as best he may. The suggestion 

as to the Dogger channels has, in fact, little to recommend it. The increase 

in the calcareousness of the Middle Lias towards the NW. is taken by Fox- 

Strangways on another page to indicate approach to a shore, where presumably 

Carboniferous Limestone was undergoing solution. 

All these inferences drawn by Fox-Strangways and his predecessors from 

the macroscopic data bear solely on the direction from which the sands were 

brought into Yorkshire; they suggest nothing as to the actual source of the 

materials. Upon this subject the microscopic investigation of the heavy 

minerals is now being brought to bear by Dr. Rastall, but the work is still in 

its infancy and unfortunately no very definite conclusions are yet available. 

It appears certain, however, from information which Dr. Rastall has kindly 

communicated to me, that the sands could not have come from any adjoining 

British source. The inference is that they were derived from the Fennoscandian 

mainland or Atlantis, probably from some part of the site of the present 

North Sea. They therefore have no bearing on the existence of land over the 

Pennines. 

The clay formations, such as the Lias and the Kimeridge Clay, give no 

1 Ibid., p. 394. 2 Ibid., p. 396. 3 Ibid., pp. 399, 401. 

4 W. H. Hudleston, 1876, P.G.A., vol. iv, p. 370. 

5 C. Fox-Strangways, 1892, loc. cit., p. 390.


indications of the source of their materials. It was suggested by Goodchild 

that the dark muddy sediment of the Lias might have been derived from the 

disintegration of Coal Measures, but it is stated that the mica flakes in the 

Lias are larger than those in the Coal Measures. 1 

South of the Market Weighton Axis all the formations thicken steadily and, 

as has been emphasized on earlier pages, the outcrops of the Jurassic formations 

cut obliquely across a trough of deposition, of which the opposite margin 

lay to the south-east. Only one definite instance is known of materials in the 

Jurassic strata of this trough having been derived from the north-west: at 

Leicester the base of the Rhaetic Beds contains small pebbles of igneous rocks 

from the neighbouring Charnwood Forest (p. 111). On the Forest the Keuper 

Marls overlap the earlier New Red rocks and rest directly upon the Archaean, 

and the pebbles at Leicester indicate that, as with some of the islands in the 

Mendip Archipelago, the surface was not submerged until during or after 

Rhaetic times. Of the later deposits, only the Northampton Sands have been 

investigated, and Mr. Skerl is of the opinion that their materials were derived 

from the south-east (p. 209). 

The Lower Lias and Rhaetic Beds of the Carlisle outlier show no abnormalities 

that could be ascribed to deposition particularly near to a shore-line; 

nor do the Liassic strata of the Shropshire outlier. 

THE AGE OF THE PRESENT HIGH FEATURES OF THE PENNINE RANGE AND THE 

LAKE DISTRICT AND THE POSSIBILITIES OF THEIR HAVING 

BEEN COVERED BY THE JURASSIC SEA. 

W r hen we examine the surface upon which the New Red rocks rest as they 

approach the Pennines we find a peneplain similar to the sub-Mesozoic peneplain 

of the South-West of England. The Trias and the Permian together 

form a conformable series, which passes across the denuded edges of the 

structures formed during the Armorican orogeny and itself takes no part in 

them. There is the same proof of enormous erosion after or during the uplift 

of the Armorican mountains, before the New Red rocks were laid down. 

Along the flanks of the Pennines the coal-basins were already determined in 

their long N.-S. synclines and the Coal Measures had been entirely removed 

from the intervening anticlines before the earliest Permian strata were laid 

across their surfaces. 2 On the west side of the Pennines, in the Ribble Valley 

at Clitheroe, one of the most easterly patches of Permian rests upon Visean 

limestone. This indicates that all the Coal Measures, the Millstone Grit and 

the Yoredale-Pendleside Series had previously been removed—amounting 

to 15,000 ft. of strata. 3 

Nevertheless, the central anticline of the South and Mid Pennines (the 

northern part of the range will be considered separately) still rises to an 

average height of 1,000-1,500 ft. above sea-level, with points over 2,000 ft. 

in Derbyshire, many hundreds of feet above any surviving New Red rocks. 

The patch at Clitheroe lies at an elevation of only some 200 ft., in a valley 

1 P. F. Kendall and H. E. Wroot, 1924, Geol. Yorkshire, p. 310. 

2 J. J. H. Teall and E. Wilson, 1880, Geol. Mag. [2], vol. vii, pp. 92-5; E. Wilson, ibid., 

1879, vol. vi, pp. 500-4; G. V. Wilson, 1926, 'Concealed Coalfield of Yorks. and Notts.', 

2nd ed., Mem. Geol. Surv., p. 54. 

3 R. H. Tiddeman, 1875, in 'Geol. Burnley Coalfield', pp. 121-2, Mem. Geol. Surv.) and 

Kendall and Wroot. 1924, loc. cit., p. 262.

THE AGE OF THE PENNINES 583 

hollowed out of the crest of an anticline, and is surrounded by hills of Carboniferous 

strata ranging from 1,000 to nearly 2,000 ft. in height; 1 it is thus analogous 

with the Permian valleys which run westward into the Culm Measures 

towards the Dartmoor highland. This suggests strongly that the South and 

Central Pennines stood high above the Permian sea and have not been first 

removed by the peneplanation and later re-elevated to their present height. 

Moreover, the difference in the fauna of the marine Permian on the two 

sides demands a barrier with only a roundabout connexion. 

That there has been re-elevation along the Pennine Axis from time to time 

can hardly be doubted. But, by analogy with comparable axes under the 

Jurassic covering, the movement is more likely to have been gradual, prolonged 

through the Mesozoic period and mostly relative to the sagging 

troughs of deposition on either side, rather than positive, paroxysmal, and 

restricted to the Tertiary period, as commonly stated. The line of the Derbyshire 

Pennines is continued accurately by the Vale of Moreton Axis, and 

if the two are truly connected, as seems probable from the relation of the 

Mendip, Malvern, North Devon and other axes to corresponding uplifts in 

the Mesozoic covering, then the Vale of Moreton Axis is a key to the history 

of the Pennine Chain. 

The movements along the Vale of Moreton Axis were probably only faint 

tremors of the main disturbances farther north, for the Vale of Moreton lay 

near the extreme south end of the anticline, where it pitched underground and 

disappeared or joined the opposite side of the trough. Yet we have seen 

(Chapter III) that the movements were enough to control deposition through 

much of the Lower and Middle Jurassic period. If a continuation so remote, 

although below water, was sufficiently near the surface to cause retarded 

deposition and repeated contemporaneous erosions, it is difficult to believe 

that the main Pennine Axis was not in part above the sea like the Mendips in 

Jurassic times. The least we can suppose is that it constituted a broad hog'sback 

of shallows, sometimes above water, sometimes submerged, separating 

the eastern from the western trough of deposition. We must also not forget 

the evidence of an island at least as late as Rhzetic times at Charwood Forest. 

The Charnwood range is only a small branch of the Pennines, and it is hardly 

likely to have stood above water while they were submerged, an island by 

itself in the middle of an extensive sea. 

The many eminent geologists who have discussed the evolution, tectonic 

and physiographical, of the Pennines and Northern England have usually 

evaded the question of the former extent of the Jurassic sea, or have dismissed 

it in a few lines, including it, if at all, simply to complete their histories. 

Goodchild wrote: 4 I have no doubt in my own mind that all the rocks up to 

the Lias, and even all the Jurassic rocks, once overspread the whole district 

and w T ere continuous with those of other parts of the kingdom.' 2 He gave 

no reasons, however. Prof. Marr reached the same conclusion at the end of an 

ingenious and interesting chain of reasoning. 3 Jukes-Browne wrote:'When discussing 

the extension of the Keuper Marls across England we came to the 

conclusion that the whole of the southern and central parts of the Pennine 

1 Kendall and Wroot, 1924, loc. cit., p. 263. 

2 J. G. Goodchild, 1889, P.G.A., vol. xi, p. 277. 

3 J. E. Marr, 1906, Q.J.G.S., vol. xlii, pp. lxxxvii-Ixxxviii.


Chain were submerged beneath the great inland sea of later Triassic time. 

From this it follows that the Liassic sea also spread over this part of England 

from Cheshire, Lancashire, and Westmoreland on the west to Yorkshire and 

Lincolnshire on the east, and thence across the whole breadth of the North 

Sea area'; and 'I strongly suspect that the Oxfordian sea spread completely 

over the greater part of the Pennine area, as the Liassic sea had done'. 1 

Messrs. Kendall and Wroot 'are driven to the conclusion that . . . the general 

lowering of level had been carried sufficiently far to bring the waters of the 

Jurassic sea over all that remained of at any rate the South Pennines. In that 

case probably all the Jurassic series was deposited over the Pennine area, 

except perhaps the heights of the northern fault blocks.' 2 Lastly, Mr. J. S. 

Turner has published a similar opinion, though adding no new evidence. 3 

I should be placing myself in an extremely unenviable position if I openly 

expressed disagreement with such a consensus of opinion. Nevertheless no 

harm can be done by reviewing the evidence brought forward in support of 

these statements, calling attention to some of the objections. The arguments, 

so far as I have been able to discover them, may be ranged under the following 

headings: 

(1) The base-lines of the Trias and the Rhsetic, when produced, pass over 

the top of the Pennines and Lake District (Jukes-Browne and Marr). 

(2) If the uplift of the present elevations was post-Triassic, as shown by 

(1), then it was probably Tertiary, because in the Mesozoic period 

'there is no evidence of great movements in the British Area', such 

as would suffice for the task (Marr; and implied by others). 

(3) If the amount of Permo-Trias present in West Lancashire were 

restored over the relict outlier of Permian in the Ingleton Coalfield, the 

top of the Keuper would be considerably higher than the Carboniferous 

rocks of the adjoining Pennines (Jukes-Browne). 

(4) Denudation during and after the Armorican uplift was so drastic that 

all features were probably lowered to such an extent as to bring them 

below the Jurassic sea-level (Kendall and Wroot). 

(5) To supply the Jurassic sediments of the Yorkshire Basin 'it seems likely 

that some land exposure of much greater area must have been drawn 

upon. The thick beds of grit at the Peak [of Yorkshire; i.e. Ravenscar] 

must have been brought by a larger river than could have been formed on 

so narrow a belt as the Pennine uplift' (Kendall and Wroot). 

(6) 'If the Skye uplift can have been sculptured into its present condition 

in late Tertiary times, the same explanation applies to Lakeland, and if 

we suppose Lakeland to have existed as land since, say, the end of New 

Red Sandstone times, it would long ago have been reduced to a nearly 

level surface by denuding agencies.' On the contrary, the district is 

physiographically young, and erosion is still in progress (Marr). 

(7) The south-easterly tilt is probably alone responsible for the preservation 

of Mesozoic rocks in the South-East of the British Isles; hence their 

absence from the North-West of England and Scotland is probably 

due to their having been removed by erosion (Marr). 

1 A. J. Jukes-Browne, 1911, Building of the Brit. Isles, pp. 266, 277. 

2 P. F. Kendall and H. E. Wroot, 1924, Geol. Yorkshire, p. 310. 

3 J. S. Turner, 1927, P.G.A., vol. xxxviii, p. 372.


When we come to examine these arguments, wre find that each one harbours 

a fallacy, which I will endeavour to the best of my ability to show up, since 

they are dangerous when allowed to remain latent. 

(1) and (2) The production of base-lines was a favourite line of reasoning 

with Jukes-Browne, who employed it throughout his book. The assumption 

is that if the base-line of the Keuper or Rhaetic passes over the top of any 

high ground separating two outcrops, the folding is subsequent to deposition, 

and therefore the sheet of sediment was originally continuous—was not 

banked up against the barrier. A good instance of the application of this 

argument is the following: 1 'The broad Derbyshire anticline lies between two 

equally deep and broad synclines, and the manner in which both Trias and 

Lias come into these basins makes it almost certain that they both dipped off 

the intervening anticline; in other words, the final arching of the anticline 

was completed by post-Jurassic flexuring.' The two words that I have placed 

in italics imply the application of argument No. (2) above, and this leads to 

such statements as the following: 'if the Keuper passed across the Palaeozoic 

ridges [of the North Pennines] then the greater part of the Jurassic series must 

have done so, and the Palaeozoic floor would have been covered by some 3,000 

to 4,000 feet of Trias, Lias and Oolites'. 2 

Now this line of argument is plausible, but it rests upon a misconception 

of the method of accumulation of the Jurassic sediments and upon a lack of 

appreciation of the tectonic movements which, as we have seen, were proceeding 

all through the Jurassic period. It is true there was no major orogeny in the 

Jurassic, comparable with the Alpine and capable of upheaving the Pennines 

and Lake District all in one spasm; but there was continual subsidence of the 

troughs of deposition, amounting altogether to 3,000-4,000 ft., compensated 

to an unknown extent by elevation of the adjacent more stable blocks. This 

subsidence was greatest in the centres of the troughs and decreased or changed 

into elevation towards the margins. Consequently the earlier strata to be 

formed (i.e. the Rhsetics and Lias) were by the end of the epoch depressed 

into deep synclinals, although the latest stratum was still being laid down 

horizontally. When the later strata were then removed from the edges of the 

troughs (because that was where they were highest and thinnest), the earlier 

layers revealed underneath would be disposed in synclinal fashion without 

having undergone any 4post-Jurassic flexuring'. The two completely different 

interpretations that can therefore be put upon the same facts are illustrated by 

95> P- 

3 

(3) The third argument depends upon the first; for it assumes that the same 

thickness of Permo-Trias was deposited at Ingleton, on the flank of the Pennines, 

as farther west, over the syncline of West Lancashire. On the view put 

forward here, an equal thickness of Permo-Trias would certainly not have 

been formed at the edge of the trough in such a position, and still less an equal 

amount of Jurassics. There would, in fact, probably have been slow sedimentation 

interrupted by erosions. It is curious that Jukes-Browne himself should 

note, on the next page, that 'round Derby and Ashbourne, where the Pennine 

axis passes below the Trias, the Bunter is reduced to a small thickness (about 

100 ft.), and the Keuper sandstones thin out entirely'. If there is this 

1 A. J. Jukes-Browne, 1911, loc. cit., p. 245. 

3 For a further discussion of these principles see Chapter III. 

2 Ibid., p. 244.


attenuation of the Trias across the axis so far south, where it was pitching 

and dying out, how much more might both Trias and Jurassic have thinned 

out over and towards the principal part of the uplift farther north ? Even at 

the Vale of Moreton much of the Jurassic is missing. 

(4) and (5) Prof. Kendall's and Mr. Wroot's first suggestion seems to me to 

be robbed of much of its weight by the fact that the denudation did not remove 

the high Carboniferous ground surrounding the Permian valley at Clitheroe. 

Moreover, drastic as this denudation certainly was everywhere, it left high 

features in the South-West, such 

as Dartmoor and the South 

Wales Coalfield, across which 

the Jurassic sea was unable to 

spread. Their other suggestion 

(5) can be readily agreed to without 

prejudicing the existence of a 

Pennine ridge. It seems certain 

that whether the Pennines were 

high above the water or deep 

beneath the sea, a large tract of 

land lay to the north and northeast 

(Fennoscandia), and that this 

supplied the sediments, not the 

small and narrow Pennine ridge. 

Any such ridge, even if it was 

above water, was too small to 

provide a catchment area adequate 

to supply the huge mass of 

deltaic sediments in Yorkshire; 

FIG. 95. A, B, c, D show stages in the subsidence 

and filling of two troughs of deposition, compensated 

by uprise of the intervening anticline. E shows the Dr. 

moreover, modern work on the 

heavy minerals being begun by 

R. H. Rastall shows that the 

same after epeirogenic uplift of the whole area and sedimentS are of the wrong Sort 

consequent subaerial denudation, with relics of strata £ u 1 

1, 2, 3 dipping off the anticline. F represents the to have Come trom the rocks 

reconstruction inferred by producing the base-lines composing the Pennines. Yet the 

Of the strata 1-4. Pennines may have been land 

nevertheless, just as Cowbridge Island was above water while the thick mass 

of sandstones derived from the mainland were accumulating to northward of 

it in the Rhaetic Period (p. 103 ; and compare fig. 97, p. 597). 

(6) Prof. Marr's comparison of the Lake District with the Skye uplift, where 

Tertiary rocks of an equal or greater hardness have been sculptured to about 

an equal extent, is a singularly apt reminder of the extreme length of geological 

time. No one could deny that the Lake District would have been converted 

to a nearly level plain had it been upheaved to its present position in 

relation to sea-level in New Red Sandstone times and had those relations 

remained the same ever since. But the present rate of erosion depends entirely 

on the relation of the ground to sea-level, a factor which cannot possibly have 

remained even approximately constant for so great a length of time. That the 

present state of erosion of the Lake District is the same as that of Skye only 

proves that the last major adjustment of sea-level took place at about the same


time (late Tertiary or early Quaternary) in the two regions. This has no 

bearing on the relations of the ancient rocks of the Lake District to the Jurassic 

sea. That there was upheaval over the site of the Lake District during the 

Armorican movements is proved by the overstep of the New Red rocks across 

Lower Palaeozoics along the present seaboard, between Whitehaven and 

Millom. And, as will be mentioned presently, there seems good reason for 

supposing that high ground survived and that the Carboniferous covering 

continued to be stripped off during the formation of the Permian of the Vale 

of Eden. Whether this high ground remained above water in Jurassic times 

or was only a region of shallows it is impossible to say; but the synclinal 

arrangement of the Lower Lias and Rhaetic Beds of the Carlisle outlier does 

not imply that the Jurassic rocks were deposited in force all over the Lake 

District, but may even indicate the reverse (see (1) above, and fig. 95). 

(7) It is in general true that the south-easterly tilt of the Tertiary epoch was 

responsible for the preservation of the Mesozoic rocks in the South-East of 

the British Isles; and that they have been removed from much of the North- 

West is a legitimate corollary. But Jurassic rocks w r ere not deposited everywhere 

in the South-East (e.g. they are absent over the London-Ardennes 

landmass) and consequently they need not have been deposited everywhere 

in the North-West. 

There is a direct bearing upon these problems in the new picture of the 

structure of the Northern Pennines that has begun to emerge as the result of 

recent work. The stratigraphical results achieved by Prof. Garwood and the 

illuminating investigations by Profs. Marr and Jones, Dr. Rastall, Mr. Turner, 

and Messrs. Trotter and Hollingworth depict the northern end of the Pennine 

Range east of the Craven, Dent and Pennine Faults as a stable block with 

a rigid foundation of Archaean rocks, more or less surrounded by geosynclinals 

filled with Lower Palaeozoic sediments. 1 In Lower Carboniferous 

times sedimentation began early over the geosynclinal troughs, but it was not 

until late in the S2-D period that the Rigid Block was submerged. 

The previous view has been that the great faults were initiated at latest in 

Carboniferous or Permo-Carboniferous times and had arrived at essentially 

their present positions by the Permian period; that the Rigid Block stood high 

above the subsided country of the Vale of Eden, where fans of torrentbreccia 

were spread out from the foot of the escarpment to form the Permian 

brockrams. Prof. Kendall explained the introduction of Lower Palaeozoic 

pebbles in the Upper Brockram and their absence from the Lower by supposing 

that in the interval between the formation of the two layers of breccia 

a movement took place along the faults, which brought up lower rocks within 

the influence of erosion. This view of the physiography of the Northern 

Pennines in New Red Sandstone times, of which Prof. Kendall was the 

champion, 2 seemed to be corroborated by Prof. Marr's conclusions as to the 

Tertiary date of upheaval of the Lake District dome. 3 

1 J. E. Marr, 1921, 'The Rigidity of North-West Yorkshire', The Naturalist, pp. 63-72; 

and O. T. Jones, 1927, 'The Foundations of the Pennines', Journ. Manchester Geol. Assoc., 

vol. i, part 1, pp. 5-14. 

2 P. F. Kendall, 1902, 'The Brockrams of the Vale of Eden . . .\ Geol. Mag. [4], vol. ix, pp. 

510-13; and 1924, Geol. Yorkshire, p. 261. 

3 J. E. Marr, 1906, loc. cit.; and 1919, Geol. of the Lake District, pp. 122-3.


Certain facts, however, make it seem possible that a complete revision of this 

view will be necessary. Messrs. Turner 1 and Trotter and Hollingworth 2 have 

brought forward evidence that in New Red times the Rigid Block actually 

lay at a lower level than its surroundings. Turner has observed that the Permian 

brockrams do not thicken and become coarser and more angular towards 

the Pennine Faults, but away from them, as if the materials had been derived 

from the south. He interprets the appearance of Lower Palaeozoic rocks in the 

Upper Brockram as a sign that between the formation of the two layers of 

brockram the Carboniferous covering over the high ground of the Howgill 

Fells and the Lake District, from which the materials were being derived, 

had begun to be worn through, so that Lower Palaeozoic rocks were exposed 

to erosion. Confirmation of this view is adduced by Trotter and Hollingworth. 

They point out that north of Armathwaite (9 miles SE. of Carlisle), where the 

adjoining Carboniferous rocks of the escarpment that overlooks the Vale of 

Eden are composed of sandstones of the Yoredale facies, there are lenticular 

beds of conglomerate in the Penrith (New Red) Sandstone made up almost 

entirely of limestone pebbles. If any pebbles in this position had been derived 

from the escarpment on the north-east they would have consisted mainly 

of sandstone: the inference is, therefore, that these came from high ground 

in the opposite direction, where the Carboniferous Limestone was being 

stripped off the Lake District. 

Turner has shown, moreover, that the westerly downthrows along the 

Outer and Middle Pennine Faults, which lowered the present Vale of Eden, 

are post-Triassic, while along the Dent and Inner Pennine Faults, which 

downthrow eastwards, the movements were late Carboniferous and preor 

early-Permian, since they do not affect the New Red rocks. He also draws 

interesting corroborative conclusions from a study of the dolomitization, to 

which the Carboniferous Limestone was subjected below the floor of the 

magnesian sea or salt lake of the Permian period. The limestone of the Rigid 

Block, east of the faults, has not been dolomitized like that on the west, and 

from this he infers that in Permian times it was protected by a thick covering 

of Yoredales, Millstone Grit and Coal Measures, through which the dolomitizing 

waters were unable to percolate. This points again to considerable 

pre-Permian depression of the Rigid Block relative to its surroundings. The 

depression was apparently brought about by movements along the Dent and 

Inner Pennine Faults; the subsequent post-Triassic movements, which 

reversed the relative levels of the Rigid Block and the Vale of Eden, occurred 

along the parallel Outer and Middle Pennine Faults. 

Along the E.-W. line of the Stublick Fault, which forms the abrupt 

northern edge of the Rigid Block, some of the protective covering of higher 

Yoredales, Millstone Grit and Coal Measures still survives as a string of 

faulted outliers extending from Midgeholme eastward to south of Hexham. 

North of the Stublick Fault region there ran in Lower Palaeozoic and Lower 

Carboniferous times a geosyncline, striking E.-W., where sedimentation began 

at a much earlier stage of the Carboniferous period than over the Rigid 

Block to the south of the fault. Over the site of this geosyncline arose during 

the Armorican orogeny the Bewcastle Anticline, the crest of which was 

1 J. S. Turner, 1927, P.G.A., vol. xxxviii, pp. 358-72. 

2 F. M. Trotter and S. E. Hollingworth, 1928, Geol. Mag., vol. lxv, pp. 433-47.


denuded down until in places (as at Kirkcambeck, 12 miles north-east of 

Carlisle) the Trias came to rest directly upon the Cementstones at the base 

of the Lower Carboniferous. Here we have proof that before the deposition 

of the Trias some 10,000 ft. of Carboniferous strata had been removed and 

therefore that the anticline had been elevated by that amount relative to 

the Rigid Block. 1 

Another geosynclinal trough of Carboniferous beds, with a pre-New Red 

anticline superimposed upon it, is traced by Messrs. Trotter and Hollingworth 

from east to west across the Rigid Block. Starting south of St. Bees 

Head and pitching east like the Bewcastle Anticline, it passes through the 

Howgill Fells and the Pass of Stainmore until lost beneath the main outcrop 

of the Magnesian Limestone at Middleton Tyas, between Richmond and 

Darlington. On this line there is an enormous overstep of the Carboniferous 

strata by the New Red rocks on both sides of the Pennines. The feature 

severs the northern end of the Rigid Block from the rest and makes of it a 

separate structural unit, which Trotter and Hollingworth term the Alston 

Block. 

The Alston Block, it is interesting to note, is surrounded on three sides 

(north, south, and west) by broad anticlines, elevated during the Armorican 

movements over the sites of previous geosynclinal troughs, much as after the 

Alpine movements the London landmass was surrounded on the same three 

sides by upraised Chalk, arched over geosynclinal troughs filled with Jurassic 

rocks. The Carboniferous and the Cretaceous strata seem to have played an 

analogous role in the two places. We are reminded of the conclusion that the 

relatively low level of the Chalk under the London Basin is due not so much 

to its having been folded down as to the bulging up of the surroundings owing 

to the compression of the buried geosynclinal troughs beneath (p. 50). 

The question of importance in our present context is: At what period was 

the Alston Block re-elevated relative to its surroundings, and when was the 

thick canopy of Millstone Grit, Coal Measures and Permo-Trias removed 

from its top ? There is a certain amount of indirect evidence. Many years ago 

Goodchild 2 pointed out the existence of relics of a peneplain, passing from the 

level tops of the Lake District mountains and the Howgill Fells across the 

New Red country eastward, until it sloped down to the foot of the Pennine 

escarpment. He believed that this peneplain was formerly continuous with 

that which is a marked feature at about 2,000 ft. at the top of the Pennine 

Range, from which Cross Fell (2,930 ft.) and a few other high points protrude 

as monadnocks; and on his view its age was Cretaceous. To Goodchild, 

therefore, belongs the credit for noticing a peneplain of post-Triassic date 

which has been displaced along the Pennine Faults. 

Goodchild's views, because often imaginatively expressed, have frequently 

been rejected or even treated with contempt. But other investigators, when 

they have become as familiar with the district as he was, have also come to 

recognize this peneplain. 3 It has now been accepted whole-heartedly by 

Trotter, who considers that it has not only been faulted along the Pennine and 

1 Trotter and Hollingworth, loc. cit. 

2 J. G. Goodchild, 1889, P.G.A., vol. xi, p. 268 and fig. 8; and Trans. Cumb. and West. 

Assoc., No. XIV, pp. 73-90. 

3 e.g. T. McK. Hughes, 1901, Proc. Yorks. Geol. Soc., vol. xiv, p. 129. 

854371 S S


Stublick Faults but also warped or gently folded, as well as having participated 

in the general south-easterly tilt of England. 1 He believes that the same peneplain 

is continued by the level top of the Chalk Wolds of East Yorkshire (at 

about 800 ft.) and therefore that the date is not Cretaceous as Goodchild 

supposed, but Tertiary—that it is, in fact, the Early Tertiary peneplain recognized 

in the Mesozoic areas of England by W. M. Davis. 

By an able study of the drainage of the region, Trotter shows that the 

faulting and gentle folding of the peneplain are events 'so recent that their 

impress is still boldly stamped on the topography'; and while they are pre- 

Glacial, he considers that they are probably not earlier than Pliocene. This 

latest movement along the faults was only enough to give rise to the present 

main topographic features—to allow the Vale of Eden and Tyne Gap to subside 

to their present low levels relative to the top of the Alston Block. The 

amount of the throw is measurable by the present height of the escarpment— 

a maximum of about 1,500-2,000 ft. If we restore the two sides of xhe fault 

as they were before the displacement, so that the peneplain is continuous once 

more, it becomes evident that there was a much greater displacement before 

the formation of the peneplain; for by joining the faulted edges of the peneplain 

we only bring Trias against Lower Carboniferous. This means that if 

the Permian and Trias and all the intervening Carboniferous Beds originally 

passed across the Alston Block, some 8,000 ft. of strata had been removed 

from the block by the time the peneplain was completed. Had this mass of 

strata been already carried away by Jurassic times, or did it remain throughout 

the Jurassic period and act as a barrier separating the east from the west ? 

Mr. Trotter considers that, since the idea of the Northern Pennines towering 

above the surrounding country in Permian times has to be replaced by a 

conception of the Rigid Block depressed relatively to its surroundings by the 

Armorican movements, the idea that the Mesozoic formations may not have 

extended across the area from east to west must inevitably collapse. This 

conclusion, however, seems too hasty. There are still many uncertain factors. 

It cannot be assumed that because the Alston Block was depressed during 

the Armorican orogeny it remained a depression all through the Mesozoic 

era. We know, in fact, that it rose to such an extent that all the extra mass of 

sediments was removed by the time the Tertiary peneplanation was completed. 

The vital factor is the date (or dates) at which this elevation took 

place. 

According to Turner, part of the post-Triassic movements along the great 

faults consisted of thrusting from the south or south-west. During this 

episode dolomitized limestone was brought into direct contact with undolomitized 

limestone and Silurian rocks were thrust over Carboniferous. 

Such pressures suggest the Miocene orogeny and were perhaps a prelude to 

the final (Miocene or Pliocene ?) subsidence along the faults. But the main 

trend of the movement was in the opposite direction, resulting in elevation of 

the Alston Block or lowering of the surrounding country. Both Turner and 

Trotter assume that this elevation took place in early Tertiary times. The 

amount of the movement is so great, however, that it seems likely that it was 

spread out over a very long time—perhaps through the whole Jurassic and 

Lower Cretaceous periods—denudation perhaps keeping pace with elevation 

1 F. M. Trotter, 1929, Proc. Yorks. Geol. Soc., vol. xxi, pp. 161-80.

SCOTLAND 591 

as movement continued along the faults. There is an example of an intra- 

Jurassic fault close at hand, at Peak (Ravenscar) (p. 180). Moreover, we 

know that the work was brought to an end by the completion of the great 

peneplain; and by comparison with other areas the date of the peneplain is 

Eocene. 

Another line of speculation as to the state of the Lake District in the Jurassic 

period is worth mentioning. We have seen that, even if Prof. Marr's evidence 

of the radial drainage demands a final doming up of the district in the Tertiary 

period, there was certainly an elevation as early as the end of Carboniferous 

times. Mr. Green considers that this earlier uplift took place along an anticline 

of NW.-SE. trend and pitch, which can be traced through the Ingleton 

and Horton-in-Ribblesdale inliers until, bending round W.-E., it is lost in the 

Pennines beyond Pateley Bridge in Nidderdale. 1 On this view the Lake District 

is nothing more than a periclinal enlargement of an anticline pitching 

to the SE. Now it is noteworthy that where this anticline loses itself in the 

centre of the Pennines it is replaced by several others having a W.-E. or 

NW.-SE. strike, which pass on eastward until they disappear beneath the 

Mesozoic covering. The most important is the Wharfe Anticline, which continues 

the earlier line of the Lake District—Horton Anticline; and this has 

been identified by Prof. Kendall with the Market Weighton Axis (p. 62). 

Therefore, if Green's view of the structure is correct, it is not unreasonable 

to suppose that in Mesozoic times the Lake District had a history similar to 

that of the Market Weighton Axis. 

(e) The Scottish Highlands 

It has been emphasized that the present occurrences of Jurassic rocks in the 

Hebrides bear no relation whatever to the original distribution of the sea 

which deposited them, but that their preservation has been determined entirely 

by faulting combined with the protective action of coverings of Tertiary lava. 

The surviving relics, in fact, represent fragments that were faulted down into 

safe positions in the solid sub-Mesozoic platform, out of reach of denuding 

agencies. 2 

Thus it would seem that, but for the faulting and the outpourings of basalt, 

there would be no trace at all of the Jurassic sediments. The most impressive 

demonstration is the occurrence of Rhaetic rocks and fossils caught up in the 

neck of the Tertiary volcano on the Isle of Arran, many miles from any other 

vestige of Mesozoic strata. Yet the Arran and other Hebridean Jurassic rocks 

show no signs of having been deposited in a very restricted area; on the 

contrary, most of them closely resemble their counterparts in England. 

Consequently, when in imagination we restore the landscape as it stood 

before the denudation, it seems that we cannot argue as Jukes-Browne was 

wont to do on the Welsh Border, that the surrounding ancient rocks were 

formerly so much higher that the Jurassics cannot have spread far beyond 

their present limits. Instead, we are bound to infer that from areas where 

mountainous tracts now form the surface, great thicknesses of Jurassic strata 

have been removed. 

1 J. F. N. Green, 1920, 'Geol. Structure of the Lake District', P.G.A., vol. xxxi,p. 126. 

2 J. W. Judd, 1878, Q.J.G.Svol. xxxiv, p. 669; and G. W. Lee, 1920, 'Mesozoic Rocks of 

Applecross, Raasay and N.E. Skye', p. i, Mem. Geol. Surv.


Judd, who made the first comprehensive study of the Jurassic rocks of 

Scotland, was so impressed by these indications that he found it 

'impossible to avoid the conviction that these patches of Secondary strata, although 

now so minute in dimensions and isolated in position, once formed portions of a 

great series of connected deposits which covered the greater part of the vast area 

[of Scotland] and attained in places a thickness of from 4,000 to 5,000 ft. . . . that 

the whole of the north and north-western portions of the British archipelago—now 

sculptured by denudation into a rugged mountain land—-were, like the south and 

south-eastern parts of the same islands, covered by sedimentary deposits, ranging 

in age from Carboniferous to Cretaceous inclusive.' 1 

This was an extreme view, and it was opposed by such authorities as Sir 

Andrew Ramsay and Professor Sollas. The latter justly remarked that 'to say 

from the present absence of Oolitic beds over large areas that such beds had 

never been was more philosophical than to deduce from it their former existence', 

and upheld the view that also 'all Wales, Devonshire, Cornwall and the 

Pennine chain have been above water since the time of the Lower Lias'. 2 

Nevertheless, it cannot be denied that there has been colossal loss by denudation, 

and that a very considerable area of what is now high mountainous 

country in the Hebrides and along the west coast must have been at one time 

covered by Jurassic and Cretaceous strata. 

Unfortunately there is no hope of gaining any idea of the former extent of 

these sediments by looking for the sub-Mesozoic peneplain, for all traces of it 

have been obliterated by two or more phases of Tertiary peneplanation. 

The loftiest mountains in Scotland, such as Ben Nevis and the Cairngorms, 

rise as monadnocks from a High Plateau at 2,000-3,000 ft., which is the most 

conspicuous physiographical feature of the Highlands. W. M. Davis ascribed 

this plateau to subaerial denudation, and he considered that, by analogy with 

other peneplains, it can hardly have been exposed to dissection longer than 

since late Mesozoic times, and that the work of dissection probably commenced 

in the Tertiary era. 3 According to Peach and Home, the arrangement 

of the Mesozoic rocks shows that 'they must have entered, largely into the 

structure of the High Plateau' 4 , and if that is so the peneplanation cannot be 

earlier than Tertiary. This conclusion falls into line with Trotter's views as to 

the Tertiary date of the peneplain at 2,000 ft. in the North Pennines, and with 

Fearnsides's conjecture regarding the one at the same height in North and 

Central Wales; hence it becomes extremely unlikely that any information on 

Mesozoic water-levels is to be gained from the peneplains in any of the highlands 

of Western and Northern Britain. 

Along most of the west coast of Scotland a still later plateau is conspicuous, 

with an upper limit at about 1,000 ft. This is partly cut in the Eocene volcanic 

and plutonic rocks and is presumably a shelf of marine erosion, like the 

1,000 ft. and lower platforms in Cornwall. Where it is found there is still less 

possibility of tracing any sub-Mesozoic peneplain. 5 Clearly, if we are to 

1 J. W. Judd, 1878, loc. cit., pp. 668-9. 

2 W. J. Sollas, in discussion of Judd's paper, ibid., p. 743. 

3 W. M. Davis, 1896, Geol. Mag. [4], vol. iii, p. 526. 

4 B. N. Peach and J. Home, 1930, Chapters on the Geology of Scotland, p. 7. 

5 Peach and Home call the 1,000 ft. the Intermediate Plateau, the lowest being the Continental 

Shelf; 1930, loc. cit., p. 2.

SCOTLAND 593 

arrive at any decision as to how much of the Highlands was covered by the 

Jurassic sea, we must approach the question from other directions. 

When Judd came to the conclusion that all Scotland was submerged and 

had the full thickness of Jurassic sediments deposited over it, he seems to have 

been influenced by two principal considerations: (i) the fact that the rocks in 

the Hebrides are not of littoral facies any more than those in England; and (2) 

the fact that it is only owing to faulting and lava-flows that any fragments 

have been preserved at all; which prompts the question: 'How much more 

may have been lost entirely, leaving no trace behind ?' Let us now examine 

the value of these considerations as arguments. 

The first may be dismissed, since all the Jurassic rocks of the Hebrides could 

have been deposited sufficiently far from a shore-line for them to contain no 

littoral deposits, without the whole of Scotland being submerged. The shore 

may have lain 10 or even 20 miles east of the existing deposits. 

The second line of argument implies that the faulting and the igneous activity 

to which the sediments owe their preservation were restricted to the area 

where the sediments are found. For if the sediments previously existed 

everywhere and their survival anywhere is directly due to these processes, then 

they should be preserved as a natural consequence wherever the faulting and 

the igneous activity have occurred. 

This raises an interesting point, because to a certain extent it is true that the 

relics of Mesozoic strata are centred precisely in the part of Scotland where 

Tertiary igneous activity and faulting were most thickly concentrated. The 

igneous activity, indeed, was virtually confined to the western coast and islands. 

The faulting seems to have been at least most frequent in the same area. 

Prof. Gregory believed that the majority of the pre-Glacial fiord-like lochs 

and valleys were due primarily to faults, 1 and, although this view has been 

questioned, it is remarkable that the faulted relics of Mesozoic rocks survive 

just in the area in which most of the fiords occur. 

But it is possible that all three phenomena—igneous activity, faulting, and 

the occurrence of Mesozoic sediments—are merely effects of some common 

cause. If the area was one of subsidence in Jurassic times, it is not improbable 

that the same crustal weakness that gave rise to the subsidence and consequent 

sedimentation was later responsible for the localization of the faulting 

and igneous outbreaks of the Eocene period. 

At least it would be very rash to assert, as Judd seems to imply, that the 

absence of Mesozoic sediments in other parts of Scotland can be attributed 

solely to the absence of those causes which conditioned their survival in the 

Hebrides—namely, lava-sheets and faulting. 

Some of the largest faults of all, which have lowered the whole surface of 

the country thousands of feet, cross Scotland from sea to sea. The most important 

examples are the great trough faults of the Central Lowland or Midland 

Valley and the Great Glen (Glenmore). It is said that there are traces 

still extant of the river-system which drained the country now occupied by the 

Central Lowland and the surrounding country before the faults came into 

1 J. W. Gregory, 1913, Nature and Origin of Fiords, pp. 172-5, and map on p. 144. All agree 

that faults often determined the sites of fiords even though the fiord form was not directly due 

to faulting; for even if we suppose fiords to be ice-deepened valleys, the pre-Glacial rivers which 

originally formed the valleys frequently selected the lines of faults as paths of least resistance.

594 PALAEOGEOGRAPHY 

existence, and that the faults are therefore (at least in the main) of Tertiary 

date; and other faults which belong to the same group cut some of the Eocene 

igneous dykes. 1 Consequently, if thick Mesozoic strata had covered the area, 

they would have been lowered by the faults and some would surely have survived—at 

least until the Pleistocene Ice Age, when the Boulder Clay would 

have been filled with their fragments. In the Great Glen it is still more noteworthy 

that Mesozoic rocks do survive also at the eastern end of the troughed 

belt (in the Brora and Ethie district), but they are to be found at the ends only. 

There is nothing to show that the faulting which gave rise to the Great Glen 

was more intense at the extremities than in the middle, and indeed such an 

idea is on theoretical grounds highly improbable. Why, then, should there be 

no traces of Mesozoic rocks throughout the central and longest part of the 

trough ? 

The only logical conclusion seems to be that the Jurassic strata were only 

deposited, at least in anything like their full thickness, on either side of the 

Highlands; that Scotland formed an island, a non-subsiding block, between 

two sinking troughs or geosynclinals. Hence, even though the Jurassic seas 

may have transgressed to an unknown extent around its edges, the general 

tendency of the area would have been one of elevation, and no great thickness 

of Jurassic sediments is likely to have been deposited upon it. 

On the other hand, the Jurassic rocks and their faunas, from the Lower Lias 

to the Kimeridge Clay, are so nearly identical on the two sides of Scotland 2 

that a direct sea-connexion is demanded. De Lapparent's maps show continuous 

sea across the North-West Highlands 3 from the time of the Lower 

Lias, 4 and Prof. Wills also submerges the North-West Highlands during the 

Oxfordian period. 5 But the present heights of the North-West Highlands are 

little short of those of the Grampians: there are large areas over 1,500 ft. high, 

and many points exceed 3,000 ft.; on the same latitude as the Jurassic area of 

Ross-shire Ben Dearg rises to 3,547 ft.; and there is a point of 3,040 ft. (Ben 

Hope) within a few miles of the north coast. All this country consists of 

ancient rocks, the relics of the Caledonian mountains, and there is no more 

reason for supposing that it was ever submerged beneath the Jurassic sea 

than for supposing that the Grampian Highlands or Snowdonia were submerged. 

Another form of connexion that is often portrayed on palaeogeographical 

maps is a narrow strait through the Great Glen, where Jukes-Browne imagined 

a river to have existed as early as the Triassic period, linking up the main 

Keuper lake with an isolated lake over the Golspie district and the Moray 

Firth. 6 But apart from the fact that this unjustifiably presupposes the 

existence of a Triassic and Jurassic Great Glen, as we have already remarked, 

if Jurassic sediments had been deposited all along it, there seems no reason 

why none should have been preserved in the middle. The central reaches of 

1 E. B. Bailey, 1910, 'Geol. East Lothian', p. 9, Mem. Geol. Surv.; and J. W. Gregory, 

1913, loc. cit., p. 175. 

2 Excepting local accidents, such as the boulder-beds in the Kimeridgian of Sutherland. 

3 The term North-West Highlands is here used as defined by Peach and Home, to denote 

the part of Scotland north and west of the Great Glen (Glenmore); the mountain mass between 

the Great Glen and the Central Lowland or Midland Valley being the Grampian Highlands. 

4 De Lapparent, 1906, Traite, p. 1126. 

5 L. J. Wills, 1929, Physiog. Evolution of Britain, p. 150. 

6 A. J. Jukes-Browne, 1911, loc. cit., pp. 248, 274; and Wills, loc. cit., p. 134.

SEA CONNEXION ROUND SCOTLAND 595 

the Great Glen would have provided an ideal place for the survival of some 

fragments of faulted Mesozoic strata had any existed there. 

In view of these difficulties in the way of supposing the Highlands or Lowlands 

to have been submerged in the Jurassic period, the simplest course 

seems to be to make the necessary connexion round the north of the North- 

West Highlands, over the low-lying tract mainly occupied by sea at the present 

day. From the lie of the Trias at Elgin, on the south side of the Moray 

FIG. 96. Sketch-map to show the supposed distribution of land 

and sea over the British Isles during the deposition of the Lower 

Lias. Sea stippled; some special shallows dotted. 

Firth, it is well-nigh certain that the Mesozoic rocks lapped round the 

Grampians across the low-lying promontory of North-East Aberdeenshire and 

Banff into the bay now occupied by the Moray, Cromarty and Dornoch 

Firths and the Coastal Lowland of Sutherland and Ross. It imposes no strain 

on probability if we imagine that they similarly lapped round the North- 

West Highlands, perhaps across part of Caithness and the Orkneys, into the 

Hebridean sea. The connexion that is demanded is one, not only from the 

Oxfordian period onward, but from the time of the Lower Lias and probably 

the Trias. 

On this view the Grampians and the North-West Highlands, which, like


the Northern Pennines, were considerably higher before the Tertiary peneplanation, 

would have stood above water in Mesozoic times. By analogy with 

other such massifs of elevated ancient rocks in Britain and on the Continent, 

upward movements would have been in excess of downward during Jurassic 

times, and there would never have accumulated those thousands of feet of 

sediments which Judd conjured up, but which only characterize geosynclinal 

regions. 

(f) The North Sea Region and the Connexions with the 

Continental Troughs 

De Lapparent 1 and most other palaeogeographers depict the greater part of 

the North Sea as submerged in Jurassic times beneath a broad channel leading 

to the Arctic Ocean. Fossils brought back in recent years from Spitsbergen 

and other Arctic islands prove that after the Triassic period there was a marine 

transgression in those regions at least as early as the time of the Upper Lias, 

and that shallow epeiric seas survived with sporadic interruptions until late 

in the Cretaceous period. The faunas of these far northern seas are of the 

same general facies as those which inhabited Europe, and they prove that the 

two areas lay within one and the same zoological province. There are many 

minor differences—in fact there is seldom specific identity—but this may be 

accounted for partly by the colder climate and partly by the fact that there was 

probably often emergence and loss of deposit in one area while there was 

submergence and deposition in the other, with the result that the faunas 

which appear most nearly comparable are not strictly synchronous. 2 However 

this may be, the correspondences are so close that there can be no doubt 

of the existence of a direct sea-connexion with North-Western Europe throughout 

most of the Mesozoic era. 

A number of the Spitsbergen fossils are more closely allied to forms found 

only on the Continent than to British species. There must, therefore, have 

been some more direct connexion between the Continent and the Arctic 

than across England by way of the Hebrides. 

These considerations make it probable that a channel or trough lay over 

at least a part of the North Sea, between the highlands of Scotland and 

Scandinavia (fig. 96). It is not by any means certain, however, that the channel 

remained always open. In the Bathonian period, for instance, when enormous 

quantities of sand were brought into the north of the British area, presumably 

by a large river or rivers from the Scandinavian highlands, so that deltaic 

and estuarine conditions prevailed on both sides of Scotland and in Yorkshire 

and Lincolnshire, it is difficult to see how any passage could have remained 

open. Probably deltaic material such as that which was carried southward on 

both sides of Scotland and all down Eastern England completely filled the 

narrow trough sea, cutting off communication with the Arctic (fig. 97). 

Interesting light has been thrown on the south-westward extension of the 

ancient landmass of Fennoscandia, and the extent to which it supplied sediment 

to the adjoining Jurassic seas, by petrographical and stratigraphical 

1 1906, Traite, maps on pp. 1126, 1189, 1211, 1225, 1239, 1245. 

z H. Frebold, 1928, 'Strat. u. Palaog. des Jura u. der Kreide Spitzbergens', Centralblatt 

fiir Min. &c., Abt. B, p. 629, and Skrifter om Svalbard og Ishavet, 1929, no. 20, and 1930, 

no. 31, with numerous palaeogeographical maps. Spath rejects Frebold's explanation in favour 

of climatic races.

FENNOSCANDIA 597 

investigations in North Germany. Brinkmann 1 and Schott 2 have shown that 

at least from Vesulian to Kimeridgian times the bulk of the clastic sediment 

deposited in the North German sea was derived from the north. Every 

formation when followed from north to south passes from sand into clay. On 

the strength of a great deal of evidence brought together from an examination 

of outcrops, borings and Drift pebbles, it is concluded that at least from the 

FIG. 97. Sketch-map to show the supposed distribution of land and sea during the 

Bathonian period (Tulitan Age). Deltaic deposits dotted. The boundary of Fennoscandia 

over Germany according to Schott. 

Parkinsonian to the Perisphinctean Ages the coast-line ran roughly E.-W. 

across the South Baltic region from Riga towards Copenhagen, and thence, 

after encircling a gulf that lay over most of Denmark, on by way of Hamburg 

and the Zuider Zee in the direction of The Wash. On this view most of the 

North Sea was land, an extension of the continent of Fennoscandia. 3 

Somewhat farther south, as we have seen in Chapters II and III, lay the 

London-Ardennes landmass, and although this was negligible as a source of 

sediment in Germany according to Schott, its existence as a large island is 

1 R. Brinkmann, 1923, 'Dogger u. Oxford des Sudbaltikums', Jahrb. Preuss. Geol. Landesanst., 

vol. xliv, pp. 477-513. 

2 W. Schott, 1930, Talaogeographische Untersuchungen iiber den Oberon Braunen und 

Unteren Weissen Jura Nordwestdeutschlands': Inaugural-Dissert., Gottingen, Abh. Preuss. 

Geol. Landesanst, N.F., Heft 133, pp. 1-51. 

3 Schott uses the name Cimbria for the south-western peninsula separated by the Danish 

Gulf (which only came into existence with the Callovian (Macrocephalitan) transgression).


manifest in the thinning out of the formations towards its shores both in 

England and in North-West Germany, and in its contributions of sediment in 

England. Its northern shore-line, striking WNW.-ESE., is found by Schott to 

be constantly in evidence owing to the attenuation of the formations southwest 

of the Teutoburger Wald, which bounds the Jurassic region of Hanover, 

Bielefeld and Osnabriick. 

Between the London-Ardennes landmass and the south-westerly extension 

of Fennoscandia the Jurassic rocks are arranged in a typical trough of deposition, 

which Schott has called the Osnabriick Strait. It strikes approximately 

SE.-NW., in the direction of East Anglia, and is crossed, like its English 

analogues, by axes of uplift running at right angles to the direction of the 

trough and causing local attenuation of the rocks. 

There can be no doubt that the Osnabriick Strait made connexion with the 

English Midland trough in Lincolnshire and the district of The Wash. This 

connexion accounts for several facts, notably the occurrence in the Coral 

Rag of Upware and Yorkshire of a group of ammonites and lamellibranchs 

which have never been found in the South of England, but which were 

described on the Continent,especially in the Department of theMeuse(p.4i6). 

It may also explain the resemblance of the Cardiocerates of Eastern Scotland 

to Russian species (p. 434); though, if a more critical study of the German 

Cardiocerates fails to reveal these species, it will have to be supposed that they 

migrated round the north of Fennoscandia by way of the Arctic. It was undoubtedly 

through the Osnabriick Strait that the Jurassic sea first invaded the 

British Isles from the Continent. The Rhaetic Beds of Germany and their 

fauna are almost identical with our own, whereas the correspondence with 

those of France is much less close. In the Rhaetic and Liassic periods the 

strait was probably wider than in Upper Jurassic times and may have covered 

a considerable area which later became part of Fennoscandia. Northward, as 

already mentioned, it seems highly probable that it was continued east of 

Scotland to the Arctic Sea. 

The direct connexion between England and the Paris Basin seems to have 

been first opened at the time of the Lower Lias. Thenceforward there was 

always a wide sea channel between Normandy and the Boulonnais, perfectly 

continuous with that between Dorset and Kent. 1 M. Lemoine has shown that 

the deepest part of the trough lay along its north-eastern side, close to the 

London-Ardennes island, from the Pays de Bray eastward along the basins 

of the Marne and the Aisne, across that of the Meuse, towards the Vosges. 

Here in a broad belt the Lias is more than 1,000 ft. thick and the Palaeozoic 

floor reaches its greatest depths below the surface. 2 This deep zone is separated 

from that in Kent by a ridge of shallows which runs approximately under 

the French coast. It appears to be a typical 'axis of uplift' with Caledonian 

strike, like those which Schott has detected crossing the Osnabriick Strait, 

and upon it the whole of the Lias is exceptionally thin (105 ft. at Abbeville, 

probably less at Rouen, and said to be nil at Havre). Little has been learnt 

about this ridge, however, for the Cretaceous covering is thick and there 

1 See W. J. Arkell, 1930, 'A Comparison between the Jurassic Rocks of the Calvados Coast 

and those of Southern England', P.G.A., vol. xii, pp. 396-411, esp. 396-7. 

2 P. Lemoine, 1930, 'Structure d'ensemble du bassin de Paris', Livre jubilaire, Soc. geol. 

France, vol. ii, pi. XLIX and L.

CONCLUSION 599 

have been few borings. The attenuation of the Jurassic rocks westward in 

Normandy is due to their approaching the margin of the trough of deposition 

and has no bearing on the subject. 

Back at the shores of the Celtic highland, we must bring our brief survey 

of British Jurassic palaeocartography to an end. 

The picture of contemporary geography which we are led to draw differs 

from those extreme reconstructions which either conjure up land almost 

wherever no Jurassic sediments are found at the present day or extend the 

sea across the whole British area from horizon to horizon. It enables us to 

recognize the significance of the outliers in Ireland and the Hebrides without 

submerging the Scottish and Welsh Highlands beneath a sea with thousands 

of feet of sediment accumulating on its bed; it admits of a strait up the western 

part of the North Sea, connecting Germany with Eastern Britain and the 

Arctic, although most of the area was occupied by the Fennoscandian mainland. 

Our picture is of a landscape diversified with rather narrow and 

strait-like seas, occupying a subsiding cleft between the mainlands of Fennoscandia 

on the one side and North Atlantis on the other, and broken by two 

elongated islands—the London-Ardennes Island in the south-east, the 

Scottish-Pennine Island in the north. 

Around the margins of the land the seas transgressed and regressed with an 

unceasing ebb and flow, as in one age subsidence exceeded elevation and in 

another elevation overcame subsidence. On the whole, however, the upward 

tendency prevailed on the land and the downward in the troughs, until in the 

end the centres of the troughs had subsided between 3,000 and 4,000 feet, 

and they had become filled with the richly-fossiliferous and inexhaustibly 

interesting series of varied sediments which we call the Jurassic System.

(6oi) 

ILLUSTRATIONS OF 

THE PRINCIPAL SPECIES OF AMMONITES 

EMPLOYED AS ZONAL INDICES IN THE 

BRITISH JURASSIC 

with the characteristic lamellibranchs of the Rhastic and Pre-planorbis 

Beds and the zonal ostracods of the Purbeck Beds. 

Mainly from photographs by J. W. TUTCHER, Esq., M.Sc. 

EXPLANATORY NOTES 

DIMENSIONS.—After the name and particulars of each specimen the 

dimensions are given, following S. S. Buckman. The first figure represents 

the maximum diameter in millimetres, the second the height 

of the last whorl, the third the thickness of the last whorl, the fourth the 

width of the umbilicus. The last three dimensions are expressed as 

percentages of the diameter. At the end comes the amount of the 

reduction or enlargement of the figure. 

TYPE SPECIMENS.—Types are designated as follows: 

Holotype: the original specimen on which a species was founded. 

Syntypes: the original specimens on which a species was founded, when 

two or more specimens were figured or described and no holotype was 

designated. 

Paratypes: any other specimens figured or referred to by the author in 

his original description as belonging to his species in addition to a 

specified holotype. 

Lectotype: a specimen selected as type by a subsequent author from 

among the original syntypes. 

Topotypes: specimens from the same horizon and locality as the original 

types. 

Chorotypes: specimens from the same district and horizon as the original 

types, but not from exactly the same locality. 

Neotype: a specimen designated as type by a subsequent author when 

the original types are lost or destroyed or too fragmentary for recognition. 

A neotype may only be chosen from among paratypes, topotypes, 

or chorotypes. 

Genotype: the original specimen on which a genus was founded. And 

so on for genosyntypes, genolectotype, &c.

(602) 

PLATE XXIX 

RHiETIC BEDS AND PRE-PLANORBIS BEDS 

PRE-PLANORBIS BEDS 

1. Oxytoma longicostata (Strickland), 

Montpelier, Bristol. J.W.T. coll. fig. Xo-6. 

2. Ostrea liassica Strickland ( = O. irregularis Schlotheim?), 

Ostrea Beds, Stoke Gifford, nr. Bristol. J.W.T. coll. fig. X 10. 

3. Lima terquemi Tate, 

Shepton Mallet, Somerset. J.W.T. coll. fig. Xio. 

4. Modiola minima Sowerby, 

Ashley Hill, Bristol. J.W.T. coll. fig. X 1-5. 

8. Pleuromya tatei Richardson & Tutcher, 

Stapleton, Bristol. J.W.T. coll. fig. Xi o. 

LANGPORT BEDS OR WHITE LIAS 

5. Dimyodon intus-striatus (Emmrich), 

Cold Knap, Barry, Glamorgan. L. Richardson coll. fig. x 2 0. 

6. Modiola langportensis (Richardson & Tutcher), 

Langport, Somerset. J.W.T. coll. fig. Xi o. 

COTHAM BEDS 

7. Pseudomonotis fallax (Pflucker), 

Kilmersden, Somerset. J.W.T. coll. fig. Xi o. 

WESTBURY BEDS OR CONTORTA SHALES 

9. Pteromya crowcombeia Moore, 

Blue Anchor, nr. Watchet. L. Richardson coll. fig. X 2-0 

(from Richardson & Tutcher, 1916, Proc.Yorks.G.S.,xix,pl.vin,fig. 1). 

10. 'Schizodus 9 ewaldi (Bornemann) (= *Axinus* cloacirius Quenst. sp. et 

Moore; = 'Isocyprina' ewaldi Healey). Genus indet. Pending determination 

of the genus, Schizodus is retained here, as in the bulk of the 

previous literature, although it and all other generic determinations 

made hitherto are certainly wrong. 

Beer Crowcombe, Somerset. J.W.T. coll., ex. Moore coll. fig. X2-o. 

11. Chlamys valoniensis (Defrance), 

Stoke Gifford, Glos. J.W.T. coll. fig. Xio. 

12. Protocardia rhcetica (Marian), 

Charlton, near Bristol. J.W.T. coll. fig. X 1-75. 

13. Mytilus cloacinus Tutcher, 

Bone Bed, Aust Cliff. J.W.T. coll. fig. X 10. 

14. 'Cardium y cloacinum Quenstedt, 

Blue Anchor, nr. Watchet. J.W.T. coll. fig. Xi o. 

15. Pleurophorus elongatus Moore, 

Aust Cliff. J.W.T. coll. fig. Xio. 

16. Pteria contorta (Portlock), 

Charlton, near Bristol. J.W.T. coll. fig. X 1-3. 

SULLY BEDS 

17. Ostrea bristovi Etheridge, 

St. Mary's Well Bay, Glamorgan. J.W.T. coll. fig. Xo-8.

PLATE XXXVII

PLATE XXXVII

PLATE XXXVII

PLATE XXXVII

(6o6) 

PLATE XXXIII 

LOWER AND MIDDLE INFERIOR OOLITE 

1. Shirbuirnia stephani Buckman, 

Sandford Lane, near Sherborne, Dorset. Chorotype. J.W.T. coll. 

117. 51.31.18. fig. X055. 

2. Hyperlioceras discites (Waagen) pars., H. discitiforme Buckman. The 

holotype of H. discites (Waagen) in the Berlin Museum has been figured 

by Buckman (1907, 'Mon. Ammonites Inf. Ool.\ Pal. Soc., p. cxxii, 

fig. 88), who says that all the British specimens differ slightly in either 

ribbing or proportions or both. He therefore regards them as distinct 

species. 

Bradford Abbas, Dorset. Topotype. J.W.T. coll. 

65. 50.20.13. fig. Xio. 

3. Ludwigella concava (Sowerby), 

Wyke, near Sherborne, Dorset. J.W.T. coll. 

71. 52.21.15. fig. Xo-8. 

4. Tmetoceras sctssum (Benecke), 

Burton Bradstock, Dorset. J.W.T. coll. 

35. 33.2845. fig. Xi-i. 

5. Brasilia bradfordensis Buckman, 

Barrofield, Beaminster, Dorset. J.W.T. coll. 

123. 48.21.21. fig. Xo-45. 

6. Ludwigia murchisorue (Sowerby), 

Bradford Abbas, Dorset. From Buckman, 'Mon. Ammonites Inf. Ool. 

PI. Ill, fig. 1. 

114. 41.26.32. fig. Xo-6.

PLATE XXXVIII

PLATE XXXVII

(6O7) 

PLATE XXXIV 

MIDDLE AND UPPER INFERIOR OOLITE 

1. Parkinsonia schlcenbachi Schlippe, 

Burton Bradstock, Dorset. G. A. Kellaway coll. 

75- 34.33.44. fig. X07. 

2. Garantiana garantiana (d'Orbigny), 

Near Sherborne, Dorset. J.W.T. coll. 

76. 38.34.36. fig. xo-75. 

3. Strigoceras truellei (d'Orbigny), 

Burton Bradstock, Dorset. J.W.T. coll. 

79. 56.36.7. fig. X0 7. 

4. Strenoceras niortensis (d'Orbigny), 

Oborne, Dorset. J.W.T. coll 

40. 35.30-41. fig. Xio. 

5. Teloceras blagdeni (Sowerby), 

Near Sherborne, Dorset. J.W.T. coll. 

41. 29.71.47. fig. Xl*2. 

6. Otoites sauzei (d'Orbigny), 

Dundry Hill, Somerset. J.W.T. coll. 

36. 42.50.23. fig. X 1*2.

(6o8) 

PLATE XXXV 

GREAT OOLITE SERIES AND CORNBRASH 

1. Macrocephalites macrocephalus (Schlotheim), 

Upper Cornbrash, Shorncote, Glos. W.J.A. coll. 

Identified by L. F. Spath and mentioned Douglas & Arkell, Q.J.G.S., 

vol. lxxxiv, p. 135. 

151- 53-52J.I2. fig. X033. 

2. Clydoniceras discus (Sowerby), 

Lower Cornbrash, South Brewham, Somerset. J.A.D. & WJ.A. coll. 

Identified by S. S. Buckman and figured T.A., plate DVI B; mentioned 

Douglas & Arkell, Q.J.G.S., vol. lxxxiv, p. 146. 

60. 60.25.0 fig.x i'O. 

3. Tulites subcontracts (Morris & Lycett), 

Great Oolite, Minchinhampton, Glos. Lectotype. Lycett coll. 

Geol. Survey Engl., No. 25610. Figd. Buckman, T.A., vol. 4, pi. CCLXX. 

86. 35.51.35. fig. xo-72. 

4. Morrisiceras morrisi (Lycett), 

Great Oolite, Minchinhampton. Topotype. J.W.T. coll. 

68. 50.64.15. fig. X0 85. 

5. Oppelia fusca (Quenstedt), 

Basal Fuller's Earth, Broad Windsor, Dorset. J.W.T. coll. 

Identified by S. S. Buckman. 

38. 55.18.9. fig. X 1*24* 

6. Zigzagiceras zigzag (d'Orbigny), 

Zigzag Bed, Crewkerne, Somerset. J.W.T. coll. 

37- 33-32-43. fig. Xi o.

PLATE XXXVII

PLATE XXXVII

(6O9) 

PLATE XXXVI 

KELLAWAYS BEDS AND LOWER OXFORD CLAY 

1. Erymnoceras reginaldi (Morris), 

Trowbridge, Wilts. Topotype. British Museum. 

430. 38.36.36. fig. X016. 

2. Kosmoceras (Spinikosmoceras) pollux (Reinecke), 

Christian Malford, Wilts. Brit. Mus., No. 62229. (The flattening 

is highly characteristic in England.) 

60. 38J.—.32. fig. X0 9. 

3. Kosmoceras (Gulielmites) jason (Reinecke), 

Gammelshausen, Wiirttemberg. Chorotype. Alte Akademie, Munich. 

After S. S. Buckman, T.A., 1924, plate Dili. 

24. 44.26.29. fig. Xio. 

4. Cadoceras sublceve (Sowerby), 

Kellaways Rock, Kellaways, Wilts. Topotype. J.W.T. coll. Figd. 

Buckman, T.A., 1922, pi. CCLXXV. 

65. 39.80.25J. fig. X076. 

5. Sigaloceras calloviensis (Sowerby), 

Kellaways Rock, Kellaways, Wilts. Holotype, Sowerby coll., Brit. 

Mus. Photographed from plaster cast; suture from another specimen 

(chorotype, ?topotype) superimposed. 

94. 47.41.22. fig. X0 63. 

6. Proplanulites koenigi (Sowerby), 

Kellaways Clay, near Chippenham, Wilts. Chorotype. J.W.T. coll. 

Suture from another specimen. 

70. 40.30.29. fig. ix-o.

(6io) 

PLATE XXXVII 

MIDDLE AND UPPER OXFORD CLAY 

1,2. Cardioceras prcecordatum R. Douvilte, 

1. Marnes k Creniceras renggeri, Jura Mountains. Paratype; from R. 

Douvill6, 1912, Mdm. Soc. gdol. France, vol. xix, p. 62, pi. iv, fig. 21. 

28. 45.33.29. fig. Xi o. 

2. Horton-cum-Studley, near Oxford. W.J.A. coll. 

38. 42.32.31. fig. Xi-o. 

3. Quenstedtoceras lamberti (Sowerby), 

Tidmoor Point, Weymouth. Topotype. J.W.T. coll. 

63. 40.25.32. fig. Xio. 

4. Creniceras renggeri (Oppel) (Ammonites cristatus Sowerby non Defrance), 

Ludgershall, Bucks. Geol Survey coll. No. 27791. 

15. 49.22.24. fig. X15. 

5. Kosmoceras pronice Teisseyre, 

Summer town Brickyard, Oxford. J.W.T. coll. 

41. 45.30.25. fig. Xio. 

6. Kosmoceras duncani (Sowerby), 1 

Summertown Brickyard, Oxford. J.W.T. coll. 

33. 42.29.29. fig. Xio. 

7. Peltoceras athleta (Phillips), 

Hackness Rock, Scarborough, Yorks. Topotype, Neotype. Brit. Mus., 

No. 89052. Identified and figured by L. F. Spath, 1931, Mem. Geol. 

Survey India, vol. ix, pi. cvi, fig. 3, and cvn, fig. 5. 

70. 28.46.49. fig. Xi-o. 

1 This specimen compares as nearly as possible with Sowerby's figure of 

Ammonites duncani; the original, which came from the Oxford Clay of St. Neots, 

is lost. Brinkmann's so-called neotype, from Etrochey, Cote d'Or (Abh. Ges. 

Wiss. Gottingen, 1929, M-P. Kl., N.S., vol. xiii, pi. 1, fig. 7), should not be 

accepted, since it bears no resemblance to Sowerby's figure and was not chosen 

from among topotypes or even chorotypes.

PLATE XXXVII

PLATE XXXVIII

(6n) 

PLATE XXXVIII 

CORALLIAN BEDS 

1. Ringsteadia anglica Salfeld, 

Iron Ore, Westbury, Wilts. Topotype. Devizes Museum. 

263. 34-I9J-37- X0 25. 

2. Perisphinctes (Dichotomosphinctes) wartce Bukowski, 

Weisser Oxfordkalk, Czenstochau, Poland. Copy of original figure, 

Beitr. z. Geol. u. Pal. Osterr.-Ungarns, vol. v, 1887, pi. xxxvn, fig. 1. 

156. 27.17.51. fig. X0 35. 

3. Perisphinctes (Dichotomosphinctes) antecedens Salfeld, 

Junction of Heersumer Schichten and Korallenoolith, near Hildesheim, 

North-West Germany. Copy of original figure, ye Jahresber. d. 

Niedersach. geol. Vereins z. Hannover, 1914, fig. 3. 

133. 27.24.55. fig. X042. 

4. Perisphinctes (Perisphinctes) martelli (Oppel), 

Holotype (Amm. btplex d'Orbigny non Sow.); locality unknown. 

From Palaeontologia Universalis, no. 51. 

268. 23.30.60. fig. Xo-2. 

5,6. Cardioceras cordatum (Sowerby), 

5,5 a. Lower Calcareous Grit, Marcham, Berks. Chorotype. Brit. 

Mus. No. 88978. 

60. 40.28.33J. fig. xio. 

6, 6 a. Lower Calcareous Grit, Shotover, Oxon. Holotype. Brit. Mus. 

Sowerby coll. 

20. 35-25.40. fig- Xio. 

7. Aspidoceras (Euaspidoceras) catena (Sowerby), 

Lower Calcareous Grit, Marcham, Berks. Topotype. Oxford University 

Museum. 

272. 28.27.51 J. fig. Xo-2. 

854371

(6X2) 

PLATE XXXIX 


1. Virgatosphinctoides wheatleyensis Neaverson, 

Kimeridge Clay, Wheatley, Oxon. Holotype. Brit. Mus. No. C. 26897. 

From Neaverson, Amm. Up. Kim. Clay, pi. 1, fig. 1. 

122. 33.2848. fig. Xo-6. 

2. Gravesia gravesiana (d'Orbigny), 

Near Auxerre, Yonne, France. Syntype, Geno-syntype. From 

Palaeontologia Universalis, No. 178, figs. T 1, T 1 a. 

85. 34.7642- fig- Xo-68. 

3. Aulacostephanus pseudomutabilis (de Loriol), 

Speeton, Yorkshire. Geol. Survey coll., No. 18150. 

Specimen identified by Dr. F. L. Kitchin. 

73. 41.26.27i. fig. X0 93. 

4. Rasenia cymodoce (d'Orbigny), 

Lectotype, Genotype. Locality unknown. From Palaeontologia 

Universalis, No. 55. 

81. 33-26J.45. fig. Xo-6. 

5. Pararasenia mutabilis (Sowerby), 

Horncastle, Lincolnshire. Holotype. British Museum, Sowerby coll. 

70. 38J.28i.36. fig. Xi-o. 

6. Pictonia baylei Salfeld, 

Wootton Bassett, Wilts. J.W.T. coll. 

135. 31.22.48. fig. X0 5.

PLATE XXXVII

PLATE XL

(6i3) 

PLATE XL 

PORTLAND BEDS AND UPPER KIMERIDGE CLAY 

1. Kerberites kerberus Buckman, 

Portland Stone, Chicksgrove, Tisbury, Wilts. Genotype, Holotype. 

J.W.T. coll. Figd. Buckman, T.A., pi. DXX. 

105. 33.41.40. fig. X076. 

2. Glaucolithites glaucolithus Buckman, 

Glauconitic Beds, Portland Sand, Long Crendon, Bucks. Genotype, 

Holotype. S.S.B. coll. From T.A., pi. cccvi a, b. 

271. 33.3548. fig. XO'3. 

3. Provirgatites scythicus (Michalski), 

'Kimeridge Clay', near Moscow. Original figure, from Michalski, 

Mem. Comite giol. Russiey 1894, vol. viii, pi. v, figs. 6a and b. 

58. 34t-3 I *39. fig- X i-o. 

(Note that the ribbing on the early whorls is not virgatotome as in 

Virgatites.) 

4. Pavlovia rotunda (Sowerby), 

Rotunda Nodules, Chapman's Pool, Dorset. Topotype. Brit. Mus., 

No. C. 26903. From Neaverson, Amm. Upp. Kim. Clayy pi. 1, fig. 6. 

96. 27.31.48. fig. xo-6. 

5. Pectinatites pectinatus (Phillips), 

Shotover Grit Sands, Shotover Hill, Oxford. Topotype. Oxford 

University Museum. 

114. 38.33J.35. fig. X0 5. 

6. Subplanites sp., 

Typical specimen in characteristic state of preservation, photographed 

by the author in situ on the foreshore, at a level 14 ft. above the Rope 

Lake Head Stone Band and about 25 ft. above the Blackstone, on the 

east side of Rope Lake Head, Dorset. (Identified by Dr. L. F. Spath.) 

33J-—«4 0 « fig. Xo-37. 

Specimens of Titanites, from the highest zone of the Portland Stone, 

are figured on pi. xxvi, p. 493.

(6I4) 

PLATE XLI 

PURBECK BEDS 

All the figures are reproduced from T. Rupert Jones's paper 'On the 

Ostracoda of the Purbeck Formation', Q.J.G.S., vol. xii, 1885, pp. 311- 

53, pis. VIII and ix. 

1-8. Cypridea punctata (Forbes) and varieties, 

Middle and Upper Purbeck: 1-3, Mupes Bay; 4, 5, Durlston Bay; 6-8, 

Ridgeway. 

9,10. Cypridea ventrosa Jones, 

Upper Purbeck, Durlston Bay. 

11-14. Cypridea granulosa (Sowerby), var. paucigranulata Jones, 

Middle Purbeck, Whitchurch? 

15-20. Metacypris forbesii Jones, 

Middle Purbeck, Ridgeway. 

21-6. Cypris purbeckensis Forbes, 

Lower Purbeck: 23, 27, Hartwell; 25, Whitchurch; the rest from the 

Vale of Wardour. 

27-8. Candona bononiensis Jones, 

Lower Purbeck, Hartwell. 

29-32. Candona ansata Jones, 

Lower Purbeck, Hartwell; and Oving (30 only).

PLATE XLI

APPENDIX I 

NOTES ON THE TERMINOLOGY OF FOSSIL CORAL REEFS, 

GEOSYNCLINES AND PENEPLAINS 

(a) Coral Reefs 

WHEN the proofs of this book were nearly completed, a paper appeared advocating 

greater precision in the terminology of fossil coral reefs and cognate structures 

(E. R. Cumings, 1932, 'Reefs or Bioherms?', Bull. Geol. Soc. America, vol. xl, 

pp. 331-52). 

The author urges that coral reefs and all 'reeflike, moundlike, lenslike or otherwise 

circumscribed structures of strictly organic origin, embedded in rocks of different 

lithology' should in future be called 'bioherms'; while 'purely bedded structures, 

such as shell beds, crinoid beds, coral beds, &c., consisting of and built mainly by 

sedentary organisms and not swelling into moundlike or lenslike forms' should be 

known as 'biostromes'. He then goes on to such suggestions as 'hermatolith' or 

'hermatobiolith' for reef rock, and 'hermatopelago' for a group of coral islands. The 

reason adduced for these innovations is alleged ambiguity in existing usage of the 

terms coral reef, coral bed, shell bed, &c.; the definition of 'reef quoted from 

Murray's Dictionary is 'A narrow ridge or chain of rocks, shingle or sand, lying at 

or near the surface of the water'. 

Admittedly the word reef carries this meaning in nautical language; but as such 

it is purely a generic term. The definition quoted fits it only when it is used in its 

generic sense. It is difficult to see how there can be any confusion when it is accompanied 

by the customary specific qualification: e.g. coral reef, reef of rocks, shingle 

reef. Even without such qualifying words, the context usually renders the meaning 

unmistakable in scientific literature; moreover, no English scientist in the midst of 

a discourse on coral structures would court confusion by referring to a 'reef' if he 

meant a reef of rocks or shingle: he would surely call it a rock ledge (cf. the Kimeridge 

Ledges, above, p. 441) or a shingle spit or a sand bar. As to 'purely bedded structures, 

such as shell beds, crinoid beds, coral beds, &c.', any author who referred to 

these as reefs would not be competent to contribute to scientific knowledge and 

might safely be ignored. 

The true test of such innovations in our terminology is their descriptive power: 

whether they make not only for the greater precision that they claim, but also for 

increased lucidity and vividness. The two following passages may be compared from 

this point of view: 

1. Ordinary English: 

The sea floor was dotted with a small archipelago of coral islets, in which 

quarries show typical reef rock made up of corals in position of growth. When 

traced outwards from the reefs, the rock is seen to pass first into beds of rolled 

corals, then into bedded detrital deposits almost entirely made up of coral debris, 

and finally into limestones with shell beds. 

2. The same passage with the so-called ambiguous terms superseded: 

The sea floor carried a hermatopelago, in which quarries show typical hermatolith. 

When traced outwards from the bioherms, the rock is seen to pass first into 

coral-biostromes and then into limestones with shell-biostromes. 

It should be noted that, in order to express the grading of the detrital beds from 

rolled corals to coral debris by the method advocated, it would be necessary to add

6i6 TERMINOLOGY OF FOSSIL CORAL REEFS 

so much qualifying or descriptive matter to the word 'biostrome' that the word itself 

would become redundant. 

I venture to suggest that Professor Cumings has fallen into the same error as did 

S. S. Buckman when he imagined that he was making himself clearer by referring 

to a 'colomorphic nomomorph' when he meant an ammonite of normal size reduced 

by the removal of the outer whorls; or by calling a deformity a 'plagiomorphic 

kakomorph'. 1 

As Dr. Seitz has remarked: 'The art of description does not consist in stringing 

a greater or lesser number of terms disjointedly together, but in bringing out in clear 

language the features that are essential and distinctive.' 2 

(b) Geosynclines 

Followers of the Haug and Kober schools will take exception to the free use made 

in Chapter XVIII of the word geosyncline. I have not used it in this way in ignorance 

of what has been said in favour of restricting the term to the much deeper 

troughs out of which the folded mountains arose; but because, having read and 

studied Der Bau der Erdey I remain unconvinced. To those who are familiar with the 

sedimentary troughs of the extra-Alpine region of North-West Europe, their secular 

downsinking and the deformation which they have undergone during orogenic 

times, Kober's rigid distinction between orogen and kratogen seems artificial. The 

difference between the deformation of the kratogen and the deformation of the 

orogen (which Kober would have us believe is something fundamental) seems to me 

to be purely one of degree. Not only do the elongate troughs of deposition on the 

kratogen answer to the American definition of geosynclines—'all the greater longcontinued 

down-flexured parts of the lithosphere'—but the folding to which they 

were subjected generally follows the lines laid down during past orogenies (as pointed 

out in Chapter III). 

Admittedly there are different classes of geosynclines, and those which were 

deepest and subsequently broke forth into mountain ranges (probably as the direct 

result of their excessive depth) should rightly be placed in a different sub-class (the 

Alpine type) from those with less violent histories (as Stille calls them, the Germanotype). 

But there is nevertheless a gradation in depth which links them all together 

as fundamentally one class of phenomenon. 3 A consideration of the sedimentary 

systems of the world reveals a network of subsiding troughs of all different degrees 

of size and depth, and periodically the deepest buckled, bringing on an orogenic 

convulsion with the formation of a range of folded mountains. As Stille has aptly 

said, if we are to restrict the term geosyncline to those troughs which have given 

rise to mountains 'we might with as much justice deny the title of wife to a wife 

because she has not brought forth a family'. 4 

(c) Peneplains 

The spelling of this word as 'peneplain' (almost a plain) or 'peneplane' (almost a 

plane surface) has now become nearly an infallible distinction between English and 

1 T.A.y vol. iii, pp. 6, 32. 

2 O. Seitz, 1929yjahrb. Preuss. Geol. Landesanst., vol. i, p. 154. 

3 The significant depth is, of course, not the depth of water, but the depth of water plus 

sediment. This gives a measure of the subsidence of the bottom. 

4 Grundfragen, p. 8. The conception of the geosyncline here given conforms with that in 

the two principal works on geosynclines by American authors—and it was in America that 

the expression was first used: see Ch. Schuchert, 1923, 'Sites and Nature of the North American 

Geosynclines', Bull. Geol. Soc. America, vol. xxxiv, pp. 151-230, and A. W. Grabau, 1924, 

'Migration of Geosynclines', Bull. Geol. Soc. China, vol. iii, pp. 208-347. Grabau gives a 

map showing Asia covered with a network of geosynclinal troughs of different ages. It is very 

doubtful whether his distinction between geosynclines (in this broad sense) and oceanic deeps 

can be maintained. He calls the latter fore-deeps; but the Indo-Gangetic plain is a typical 

fore-deep in a tectonic sense, and because this is filled with sediment he calls it a geosyncline. 

The presence or absence of a plentiful supply of sediment is surely an extraneous factor.

GEOSYNCLINES AND PENEPLAINS 617 

American writings. It is not on this account, however, that I have adopted peneplain. 

The question has been fully discussed by Professor D. W. Johnson in his Shore 

Processes and Shoreline Development (1919, pp. 164-9). defines his use of certain 

terms as follows: '(1) The level erosion surface produced in the ultimate stage of any 

cycle will be called a plane. (2) The undulating erosion surface of moderate relief 

produced in the penultimate stage of any cycle will be called a peneplane. (3) A lowrelief 

region of horizontal rocks will be called a plain? And later he states: 4 A peneplain 

is not "almost a plain" of horizontal sediments, but is almost a plane surface 

in the mathematical sense of the term; therefore, "peneplane" more nearly expresses 

the true meaning of the term than does the older and commoner spelling.' 

The British reader will at once detect in these passages an unfamiliar element in 

the definition of a 'plain', which seems unwarrantably to be made to depend on the 

horizontality of the strata. In English the expression carries no such implications 

regarding the strata. The prototypes of plains, such as Salisbury Plain, the Plain 

of York, the Plain of Esdraelon, &c., were so called centuries before any idea of the 

stratification can have been present in the minds of those who conferred the names. 

Plain in English, in fact, simply means 'a level tract of country' 1 and nothing more. 

Therefore the peneplains referred to in Chapter XVIII, whether of marine or subaerial 

origin, are best described as 'almost plains'. It was certainly this meaning, 

rather than almost mathematically plane surfaces, that W. M. Davis expressed when 

he first introduced the word as 'peneplain'. 

APPENDIX II 

LIST OF 120 STAGE-NAMES HITHERTO PROPOSED FOR PARTS OF 

THE JURASSIC SYSTEM IN EUROPE, WITH REFERENCES. 

Arranged approximately in descending stratigraphical order, synonyms in order of 

date. 

May.-Eym., 1864, 1881, 1884, 1888, refer to the four works by C. D. W. Mayer- 

Eymar, enumerated in the bibliography, p. 624. 

CLAVINIAN. Jukes-Browne, 1884. Geol. Mag. [3], vol. i, p. 526. Clavinium = 

Weymouth, Dorset. = Middle and Upper Oolites. 

GLEVONIAN. Jukes-Browne, 1884. Geol. Mag. [3], vol. i, p. 526. Glevonium = 

Gloucester. = Lower Oolites up to Cornbrash incl. 

PURBECKIEN. Brongniart, 1829. Tabl. terr. sed. = Purbeck Beds. 

DUBISIEN. Desor, 1859. fitude Jura neuchat., p. 45. = Purbeckian of Doubs and 

the Jura Mts. 

TITHONIAN. Oppel,1865. Zeitschr. Deutsch Geol. Gesell.,vol.xvii,p. 535 = Marine 

Purbeckian of the Alps. Tithon was spouse of Eos (Aurora), Goddess of the Dawn 

(ref. dawn of Cretaceous). Discussed Haug, 1898, Bull. Soc. geol. France, vol. 

xxvi, pp. 197-228. Restr. Spath, 1923, Q.J.G.S., vol. lxxix, p. 304. 

AQUILONIAN. Pavlow, 1891. Bull. Soc. natur. Moscou, N.S., vol. v, p. 550; & 1896, 

Q.J.G.S., vol. Iii, p. 542. Aquilo, Nord, France. = Marine Portland-Purbeck 

pars. Discussed Spath, 1923, Q.J.G.S., vol. lxxix, p. 304. 

ALLOBROGIEN. Rollier, 1909. Compte rendu, 9 e Congres Assoc. franc-comtoise a 

1 Oxford Dictionary.

618 LIST OF 120 STAGE-NAMES HITHERTO PROPOSED 

Pontarlier, pp. 13-30; and see Mem. Soc. pal. Suisse, 1917, vol. xlii, p. 624. = 

Purbeck and Portland Beds of the 'Rhodano-Swabian Province'. 

PORTLANDIEN. Brongniart, 1829. Tabl. terr. sed. = Portland Beds. 

FREIXIALIN. Choffat, 1887. Rech. terr. second, au sud du Sado, Sec£ao dos Traba- 

Ihos Geologicos, vol. i, p. 307. Freixial, Portugal. = Portlandian of Portugal. 

KIMMERIDIEN. Thurmann, 1833. Essai sur les soulevemens jurassiques du Porrentruy. 

Mem. Soc. Hist. nat. Strasbourg, vol. i, 2 livr., p. 12. 

KIM^RIDGIEN. d'Orbigny, 1846-9. Pal. frang. terr. jurass., vol. i, p. 610. = Lower 

Kimeridge Clay. 

BOULOGNIAN. Blake, 1880. Q.J.G.S., vol. xxxvi, p. 196. See Bolonian. 

BOLONIAN. Blake, 1881. Q.J.G.S., vol. xxxvii, p. 581. Boulogne-sur-Mer, France. 

= Upper Kimeridge Clay, between the clays with Exogyra virgula and the 

Portland Beds. = Portlandien inferieur, sensu gallico. 

BOLONIN. May.-Eym., 1888. 

BOULONIEN. Pavlow, 1891. Bull. Soc. natur. Moscou, N.S., vol. v, p. 550. 

BONONIAN. Pavlow, 1896, Q.J.G.S., vol. Iii, p. 542. Bononia = Boulogne-sur- 

Mer. = Portland Beds sensu stricto by definition, though apparently only intended 

as a different spelling of Bolonian, Blake. 

VOLGIEN. Nikitin? Defined as the 'Wolgaformation' by Nikitin, 1881, Jura-Ablag. 

zw. Rybinsk, Mologa u. Myschkin, Mem. Acad. Imp. Sci. St. Petersburg [7], 

vol. xxviii, p. 36. = Upper Kimeridgian of Russia (River Volga). Discussed 

Spath, 1923, Q.J.G.S., vol. lxxix, p. 304; and Haug, 1898, Bull. Soc. geol. 

France [3], vol. xxvi, pp. 197-228. 

HAVRIEN. Brongniart, 1829. Tabl. terr. sed. = Kimeridgian of Havre. = Lower 

Kimeridgian. 

VIRGULIEN. Thurmann, 1852. Mitth. Bern. Naturf. Gesell., p. 217. = Lower 

Kimeridge Clay with Exogyra virgula. 

SOLENHOFIN. May.-Eym., 1881. Solenhofen, Bavaria. = nom. nov. for Virgulien. 

= Lower Kimeridgian pars, above the Pterocerian (Bannein). 

SALINIEN. Rollier, 1909. Compte rendu, g e Congres Assoc. franc-comtoise a 

Pontarlier, pp. 13-30; and see Mem. Soc. pal. Suisse, 1917, vol. xlii, p. 624. 

Salins, near Besanson, Jura. = Virgulien of France, = Solenhofin. 

DANUBIEN. Rollier, 1909. Compte rendu g e Congres Assoc. franc-comtoise a 

Pontarlier, pp. 13-30; and see Mem. Soc. pal. Suisse, 1917, vol. xlii, p. 624. = 

Salinien of 'Rhodano-Swabian Province'; all between Elsgovian and Bononian. 

PTEROCERIEN. Thurmann, 1852. Mitth. Bern. Naturf. Gesell., p. 217. = Lowest 

Kimeridgian, zone of Pteroceras oceani, below the range of Exogyra virgula. 

BANNEIN. May.-Eym., 1881. = Marls of Banne, Jura salinois; see Marcou, 1848, 

Jura salinois, p. 104. = Lo. Kimeridgian (Pterocerian) of Porrentruy, Jurabernois. 

ELSGOVIEN. Rollier, 1909. Compte rendu, 9 E Congres Assoc. franc-comtoise a 

Pontarlier, pp. 13-30; and see Mem. Soc. pal. Suisse, 1917, vol. xlii, p. 624.= 

Marls of Banne. = Pterocerian. = Bannein. 

CRUSSOLIEN. Rollier, 1909. idem; Tenuilobatus and Aulacostephanus zones and 

coral rag of Nattheim. = Elsgovien. = Bannein of 'Rhodano-Swabian Province*. 

SEQUANIEN. (Thurmann MS.), Marcou, 1848. Rech. geol. sur le Jura salinois; 

Mem. Soc. geol. France [2], iii, pp. 96, 102-3. Sequania = Franche-Comte 

(Jura). = Astarte supracorallina Beds = Astartien = Lower Kimeridgian, Thurmann. 

As used by De Loriol in the Boulonnais and thence by Arkell for Dorset, 

this includes the Upper Corallian, an extension that does not seem legitimate. 

ASTARTIEN. Thurmann, 1852. Mitth. Bern. Naturf. Gesell., p. 217. = Astarte 

supracorallina Beds of Porrentruy, immediately below the Pterocerian. = Sequanian.

FOR PARTS OF THE JURASSIC SYSTEM IN EUROPE 619 

DICERATIEN. fitallon, 1857. Esquisse Descr. geol. Haut-Jura; Annales Soc. agric. 

et indust. Lyon, vol. i, pp. 253, 292. = Reef facies of Sequanian with Dicer as 

arietina. 

RANDENIEN. Rollier, 1897. Le Malm du Jura et du Randen, Compte rendu, 

Congres geol. internat., Sess. vi, Zurich, 1894(1897), p. 337. Randen, Switzerland. 

= Ammonitiferous and spongiferous facies of the Sequanian. 

CORALLINIEN. Etallon, 1861. Mem. Soc. Emul. Doubs, vol. vi, p. 53. = Reef facies 

of Upper Sequanian of the Jura. 

VERDUNIN. May.-Eym., 1881. = Upper Sequanian of Verdun, Lorraine. 

FRINGELIN. May.-Eym., 1881. = Lower Sequanian of Fringeli, Jura bernois. 

CORALLIEN. Thurmann, 1833. Mem. Soc. Hist. nat. Strasbourg, vol. i, p. 14. 

D'Orbigny, 1845, Pal. fran

620 LIST OF 120 STAGE-NAMES HITHERTO PROPOSED 

VILLERSIEN. Lapparent, 1893. Traite, ed. 3; emend. = Upper Divesian,= Upper 

Oxford Clay + Lower Calc. Grit. 

KELLOVIEN. d'Orbigny, 1844. 

CALLOVIEN. d'Orbigny, 1846. Pal. fran?. terr. jurass., vol. i. Callovium = Kellaways, 

Wilts. = Kellaways Beds + Lower Oxford Clay, zones of Proplanulites 

koenigi to Kosmoceras jason. Emend. Oppel, 1858, Die Juraformation, p. 506. 

CHANASIAN. Parona and Bonarelli, 1895. Mem. Acad. Sci., &c., Savoie [4], vol. vi, 

p. 30. Chanaz, Savoy. = Kellaways Beds. 

NIORTIN. May.-Eym., 1881. Niort, Deux-Sevres, France. = Lower Callovian sensu 

lato (Upper Cornbrash), zone of Macrocephalites macrocephalus. 

BEDFORDIN. May.-Eym., 1881. Bedford, England. = Cornbrash. 

HANDTHORPIAN. 1 

STALBRIDGIAN. >Buckman, 1927. Q.J.G.S., vol. lxxxiii, p. 7. 

CLOSEWORTHIAN. J 

Handthorpe, Lines.; Stalbridge and Closeworth, Somerset. = Cornbrash. For 

criticism see Douglas and Arkell, 1928, Q.J.G.S., vol. xxxiv, pp. 125-7. 

HINTONIAN. "J 

CORSHAMIAN. I Buckman, 1927. Q.J.G.S., vol. lxxxiii, p. 7. 

WYCHWOODIAN. J 

Hinton Charterhouse and Corsham, Wilts.; Wychwood Forest, Oxon.; = Forest 

Marble. See Arkell, 1931, Q.J.G.S., vol. lxxxvii, p. 595. 

BRADFORDIEN. Desor, 1859. fitude Jura neuchat., p. 85. = Bradford Clay of 

Bradford-on-Avon, Wilts. + Forest Marble. 

BATHONIAN. D'Omalius d'Halloy, 1843. Precis elementaire de Geologie, p. 470. 

= Dogger. Restr. d'Orb., Pal. fran£. terr. jurass., vol. i, p. 607, to Great Oolite 

Series (+Vesulian pars). 

BATHIEN. May.-Eym., 1864. Bathonian+Bajocian. Restr. May.-Eym., 1884, to 

Cornbrash-f Bradford Clay. 

MANDUBIEN. Marcou, i860. Lettres du Jura, p. 344. Mandubii = people of the 

Jura Mts. = Bathonian of the Jura. 

FALAISIN. May.-Eym., 1881. Falaise, Normandy. = Middle Bathonian; Great 

Oolite with Nerinea voltzi. 

VIISULIEN. Marcou, 1848. Mem. Soc. geol. France [2], vol. iii, p. 73. Vesulum = 

Vesoul, Haute-Saone. Marls of Vesoul, with Ostrea acuminata and O. knorri. = 

Fuller's Earth+Bath Oolite (pro parte) by original definition. Emend. May.- 

Eym., 1881 = Cadomin+Stonesfieldin+Falaisin (i.e. Great Oolite Series less 

the Bradford Clay and higher beds). 

STONESFIELDIN. May.-Eym., 1881. Stonesfield Slate Beds+Oolithe miliaire. 

Later (1884) included by Mayer-Eymar in his Cadomin. 

CADOMIN. May.-Eym., 1881. Cadomum = Caen, Normandy. = Fuller's Earth, 

Lower Vesulian, marls with Ostrea acuminata+Czzn Stone. 

FULLONIAN. Woodward, 1894. Jurassic Rocks of Britain, vol. iv, p. 229. = Fuller's 

Earth of England. 

EHNINGIN. May.-Eym., 1881. Ehningen, Wiirttemberg. = Upper Inferior Oolite, 

zone of Parkinsonia parkinsoni (sensu lato). 

BAJOCIAN. d'Orbigny, 1847. Pal. fran£. terr. jurass., vol. i, p. 606. Bayeux, 

Normandy. = Inferior Oolite Series, from the zone of Ludwigia murchisonce 

to that of Zigzagiceras zigzag. Restricted by the founding of the Aalenian. 

LAEDONIEN. Marcou, 1848. Rech. giol. Jura salinois, Mem. Soc. geol. France [2], 

vol. iii, p. 70. Laedo = Lons-le-Saunier, Switzerland. = Bajocian, pars.

FOR PARTS OF THE JURASSIC SYSTEM IN EUROPE 621 

TORGONIEN. Rutot and Van den Broeck, 1885. Sketch Geol. Belgium; Geol. Assoc., 

London, p. 38 = Bajocian of the Ardennes. 

SCARBOROUGHIN. May.-Eym., 1881. Scarborough, Yorks. = Bajocian, pars, zone 

of Stephanoceras humphriesianum (sensu lato). 

MACONIN. May.-Eym., 1881. Macon, Saone et Loire. = Bajocian, pars, zone of 

Sonninia sowerbyi. 

AALENIAN. May.-Eym., 1864. Aalen, Wiirttemberg. = Zones of Lioceras opalinum 

and Ludwigia murchisonce (sensu lato). 

CHELTENHAMIN. May.-Eym., 1881. = Upper Aalenian. = Lower Inferior Oolite 

of Cheltenham. 

GUNDERSHOFIN. May.-Eym., 1881. Gundershofen, Alsace. = Lower or Middle 

Aalenian = Gundershofen Schichten, limestones with Trigonia navis. 

BOLLIN. May.-Eym., 1881. Boll, Baden, Germany. = Lower Aalenian. 

OPALINIEN. Renevier, 1874. Tabl. terr. sed., ed. 1. = Lower Aalenian, zone of 

Lioceras opalinum. 

TOARCIEN. d'Orbigny, 1849. âl. fran£. terr. jurass., vol. i, p. 106. Toarcium = 

Thouars, Deux-Sevres, France. = Upper Lias. 

THOUARSIEN. May.-Eym., 1864. 

MUSSONIEN. Rutot and Van den Broeck, 1885. Sketch Geol. Belgium; Geol. Assoc., 

London, p. 38. Musson, Belgium. = Toarcian of the Ardennes. 

ALFELDIN. May.-Eym., 1881. Alfeld, near Hanover, Prussia. = Upper Toarcian 

= Yeovilian. 

YEOVILIAN. Buckman, 1910. Q.J.G.S., vol. lxvi, p. 88. Yeovil, Somerset. = Upper 

Toarcian, subzones of Grammoceras striatulum to Dumortieria moorei. 

ALDORFIN. May.-Eym., 1881. 

ALTDORFON. May.-Eym., 1888. Altdorf, nr. Niirnberg, Bavaria. = Lower Toarcian 

= Whitbian. 

WHITBIAN. Buckman, 1910. Q.J.G.S., vol. lxvi, p. 88. Whitby, Yorkshire. = 

Lower Toarcian, subzones of Dactylioceras tenuicostatum to Haugia variabilis. 

LIASIEN. d'Orbigny, 1849. Pal. franf. terr. jurass., vol. i, p. 605. = Middle and part 

of Lower Lias. Adopted for whole of the Lias by Jukes-Browne, 1884, Geol. Mag. 

[3], vol. i, p. 526. 

PLIENSBACHIEN. Oppel, 1858. Die Juraformation, p. 815. Pliensbach, near Boll, 

Wiirttemberg. = Liasien d'Orb. 

CHARMOUTHIAN. May.-Eym., 1864. Charmouth, Dorset. = Pliensbachien. 

VIRTONIEN. Rutot and Van den Broeck, 1885. Sketch Geol. Belgium; Geol. Assoc., 

London, p. 38. Sandstone of Virton, Belgium. = Pliensbachian. 

CYMBIEN. Leymerie, 1872. Bull. Soc. geol. France, vol. xxix, p. 168. = Middle 

Lias with Gryphcea cymbium. = Upper Pliensbachian. 

BANZIN. May.-Eym., 1881. Banz, near Coburg, Bavaria. = Upper Pliensbachian. 

DOMERIEN. Bonarelli, 1894. Atti della R. Accad. delle Scienze di Torino, vol. xxx, 

p. 85; and 1895, Rendiconti Reale Istituto Lombardo, Ser. 2, vol. xvxiii, pp. 326, 

415. Monte Domero (Domaro), Lombardy Alps. = Middle Lias = Upper 

Pliensbachian. 

MENDIN. May.-Eym., 1881. Mende, Lozere, France. = Middle Pliensbachian, 

with Lytoceras fimbriatum. 

ROTTORFIN. May.-Eym., 1881. Rottorf, Brunswick. = Lower Pliensbachien, zones 

of Tragophylloceras ibex and Uptonia jamesoni. — Carixian, pars. 

CARIXIAN. Lang, 1913. Geol. Mag. [5], vol. x, p. 401. Carixa = Charmouth. = 

Lower Pliensbachian, zones of Prodact. davoei, Trag. ibex and Uptonia jamesoni.

622 LIST OF STAGE-NAMES 

ROBINIEN. Rollier, 1915. Eclogae Geologicae Helvetian, vol. xiii, p. 374. Robin 

Hood's Bay, Yorkshire. = Zones of Prodactylioceras davcei, Uptonia jamesoni and 

Deroceras armatum. 

SINEMURIEN. d'Orbigny, 1849. f ran 9- terr. jurass., vol. i, p. 604. Sinemurum = 

Semur, Cote d'Or. = Lower Lias pars. 

SEMURIEN. May.-Eym., 1864. 

ARLONIAN. Rutot and Van den Broeck, 1885. Sketch Geol. Belgium; Geol. Assoc., 

London, p. 38. Marls of Arlon, Belgium = Lower Lias of Belgium. 

LOTHARINGIEN. Haug, 1911. Traite de Geologie, p. 961. Lothringen = Lorraine. 

= Lower Lias above Hettangian. 

BALINGIN. May.-Eym., 1881. Balingen, Wiirttemberg. = Upper Sinemurian, 

zones of Echioceras raricostatum, Oxynoticeras oxynotum and Asteroceras obtusum. 

LOURNANDIN. May.-Eym., 1888. Lournand, Saone-et-Loire. = Upper Sinemurian. 

= Balingin, May.-Eym., 1881. 

FILDERIN. May.-Eym., 1881. Filder, near Stuttgart, Germany. = Lower Sinemurian, 

zones of Arnioceras semicostatum and Coroniceras bucklandi. 

SuiiViEN. Rollier, 1915. Eclog. Geol. Helvet., vol. xiii, p. 374. Suevie = fr. 

Swabia. = Zones of Arnioceras semicostatum, Coroniceras bucklandi, Scamnoceras 

angulatum, Psiloceras planorbis and Pteria contorta (outside the Mediterranean 

Province). 

HWICCIAN. Hwiccas = people of Gloucester, Worcester and part of Warwick. 

WESSEXIAN. Wessex = the kingdom of the West Saxons. 

RAASAYAN. Raasay = island in the Hebrides. 

DEIRAN. Deira = the kingdom embracing Yorkshire. 

MERCIAN. Mercia = the kingdom embracing the Midlands. 

LYMIAN. Lyme Regis, Dorset. 

Buckman, 1917. Q.J.G.S., vol. lxxiii, pp. 263-77. = Sinemurian-j-Carixian. 

HETTANGIEN. Renevier, 1864. Not. Alp. vaud., vol. i, p. 51. Hettange, Lorraine. = 

Sandstone with Psiloceras planorbis. 

RHETIEN (RH^TIEN). Guembel, 1861. Bay. Alp., p. 122; and Renevier, tabl. terr., 

ed. 1. Rhaetia = Rhaetic Alps (Grisons). Rhaetic Beds. 

SOMERSETIAN. Richardson, 1911. Q.J.G.S., vol. lxvii, p. 73. = Cotham Beds-B 

Langport Beds + Watchet Beds of Somerset, England. = Upper Rhaetic. 

KCESSENIN. May.-Eym., 1881. (PSuess, 1852.) Kcessen or Kossen, Tyrol. = Pteria 

contorta zone and Bone Bed. = Lower Rhaetic.

BIBLIOGRAPHY 

1. Classification and correlation . . . . . . . . 623 

2. Underground structure and deep borings . . . . . . 626 

3. Contemporaneous tectonics . . . . . . . . 628 

4. General regional works . . . . . . . . . 629 

5. Works dealing mainly with the Rhaetic Beds . . -631 

6. „ ,, ,, Lower Lias . . . . . . 634 

7. ,, ,, ,, Middle and Upper Lias . . . . 638 

8. ,, ,, ,, Inferior Oolite Series . . . . 642 

9. ,, „ ,, Great Oolite Series and Cornbrash . . 647 

10. „ ,, ,, Oxford Clay and Corallian Beds . .651 

11. ,, „ ,, Kimeridge Clay and Portland Beds 655 

12. ,, ,, ,, Purbeck Beds . . . . . 657 

13. Excursions of the Geologists' Association to Jurassic localities, arranged 

geographically . . . . . . . . . '659 

14. Palaeontological works not classifiable under stratigraphical headings . . 662 

15. Palaeogeography . . . . . . . . . . 669 

Note: District and Sheet Memoirs, sections and maps of the Geological Survey 

are not included, because a complete list is published and may be obtained cheaply 

from the Geological Survey Museum, London. 

ABBREVIATIONS 

The following contractions are used throughout the text, in footnotes, and in the bibliography: 

Q.J.G.S. Quarterly Journal of the Geological Society, London. 

P.G.A. Proceedings of the Geologists* Association, London. 

J.R.B., 1892, 1893, 1894, 1895. Jurassic Rocks of Britain, vols, i-v, by C. Fox-Strangways 

(vol. i, 1892) and H. B. Woodward (vols, ii-v); Memoirs of the Geological Survey of Great 

Britain. 

T.A. Type Ammonites (including Yorkshire Type Ammonites), by S. S. Buckman. 

Proc. Cots. N.F.C. Proceedings of the Cotteswold Naturalists' Field-Club. 

The other abbreviations used are self-explanatory. 

THEORY AND PRACTICE OF CORRELATION AND CLASSIFICATION 

IN THE JURASSIC SYSTEM 

ARKELL, W. J., 1930. A Comparison between the Jurassic Rocks of the Calvados 

Coast and those of Southern England. P.G.A., vol. xii, pp. 396-411. 

BLAKE, J. F., 1881. On the Correlation of the Upper Jurassic Rocks of England with 

those of the Continent. Part I, The Paris Basin. Q.J.G.S., vol. xxxvii, pp. 497-587. 

BLANFORD, W. T., 1884. On the Classification of Sedimentary Strata. Geol. Mag. [3], 

vol. i, pp. 318-21 and Comptesrendus, Congres g6ol. int., Session iii, Berlin. Criticism 

by Jukes-Browne, Geol. Mag. [3], vol. i, pp. 525-6, and reply, ibid., vol. ii, 

pp. 239-40. 

BORN, A., 1920. Die Bedeutung der Meeresstromungen fiir die geologische Zeitrechnung. 

Ber. Senckenb. Naturf. Gesell., 1920, pp. 207-17. 

BOSWELL, P. G. H., 1921. Sedimentation, Environment and Evolution in Past Ages. 

Proc. and Trans. Liverpool Biol. Soc., Presidential Address, vol. xxxv, pp. 5-28. 

BUCKMAN, S. S., 1891. The Ammonite Zones of Dorset and Somerset. Rept. Brit. 

Assoc. (Cardiff), p. 655; and Geol. Mag. [3], vol. viii, pp. 502-4. 

, 1898. On the Grouping of some Divisions of so-called 'Jurassic' Time. 

Q.J.G.S., vol. liv, pp. 442-62. 

, 1902-3. The Term Hemera. Geol. Mag. [4], vol. ix, pp. 554-7 and vol. x, 

pp.95-6. 

, 1917-20. Jurassic Chronology. Q.J.G.S., vol. lxxiii, pp. 257-327, and vol. 

lxxvi, p. 62. 

, 1922-5. Chronology [Jurassic]. T.A., vol. iv, pp. 5-54; vol. v, pp. 34-55,71-8. 

8.^71

624 BIBLIOGRAPHY 

CHAMBERLIN, T. C., 1909. Diastrophism as the Ultimate Basis of Correlation. 

Journ. Geol. Chicago, vol. xvii, pp. 685-93. 

CORROY, G., 1927. Synchronisme des horizons jurassiques de Test du bassin de 

Paris. Bull. Soc. geol. France [4], vol. xxvii, pp. 95~H3- 

DAVIES, A. M., 1930. The Geological Life Work of Sidney Savoury Buckman. 

P.G.A., vol. xli, pp. 221-40. 

DIENER, C., 1918. Die Bedeutung der Zonengliederung fur die Frage der Zeitmessung 

in der Erdgeschichte. Neues Jahrb. fur Min., &c., Beil.-Bd. xlii, 

pp. 65-172. 

, 1925. Grundzuge der Biostratigraphie. 

ELLES, G. L., 1924. Evolutional Palaeontology in Relation to the Lower Palaeozoic 

Rocks. Rept. Brit. Assoc. for 1923, pp. 83-107. [For discussions of theory.] 

ETHERIDGE, R., 1881. On the Analysis and Distribution of the British Jurassic Fossils. 

Q.J.G.S., vol. xxxviii, pp. 59-236. 

FIEGE, K., 1927. Die palaontologischen Grundlagen der geologischen Zeitmessung. 

FRAAS, O., 1851. On the Comparison of the German Jura Formations with those of 

France and England. Q.J.G.S., vol. vii, pp. 42-83. 

FREBOLD, H., 1924. Ammonitenzonen und Sedimentationszyklen in ihrer Beziehung 

zueinander. Centralblatt fur Min., &c., 1924, pp. 313-20. 

GOODCHILD, J. G., 1904. On Unconformities and Palaeontological Breaks in Relation 

to Geological Time. Trans. Edinburgh Geol. Soc., vol. viii, pp. 275-314. 

HEBERT, E., 1875. Les mers anciennes et leur rivages dans le bassin de Paris, ou 

classification des terrains par les oscillations du sol. i re partie, Terrain jurassique, 

Paris. 

HUDLESTON, W. H., & BLAKE, J. F., 1888-91. Report of Sub-Committee No. 3 on 

Classification and Nomenclature. A, Jurassic, a. The Oolites, b. Lias and Rhaetic. 

Compte rendu, Congres g6ol. int., Session iv, London, 1888, Appendix, 

pp. B 81-B 118. 

JUKES-BROWNE, A. J., 1903. The Term < Hemera\ Geol. Mag. [4], vol. x, pp. 36-8 

[Term Secule introduced]. (See reply by Buckman, pp. 95-6.) 

KITCHIN, F. L., 1919. The Faunal Characters and Correlation of the Concealed 

Mesozoic Rocks in Kent. Sum. Prog. Geol. Surv. for 1918, pp. 37-45. 

LANGE, W., 1931. Die biostratigraphischen Zonen des Lias a und Vollraths petrographische 

Leithorizonte. Centralblatt fur Min., &c. B., 1931, pp. 349-72. 

LAUX, N., 1924. La Methode analytique Buckman et son application a T£tude du 

systeme jurassique. Bull. Soc. geol. France [4], vol. xxiv, pp. 198-212. 

MARCOU, J., I 857-60. Lettres sur les Roches du Jura et leur distribution geographique 

dans les deux Hemispheres. Paris. 

MARR, J. E., 1905. The Classification of the Sedimentary Rocks. Q.J.G.S., vol. lxi, 

pp. lxi-lxxxvi. 

MAYER-EYMAR, C. D. W., 1 1864. Tableau synchronistique des terrains jurassiques. 

Zurich. (Folding sheet.) 

, 1881. Classification internationale, naturelle, uniforme, homophone et pratique 

des terrains de sediment, suivie dans un cours de stratigraphie. Zurich. 4to. 

, 1884. Classification et terminologie internationales des Stages naturels des 

terrains de sediment. Zurich. 4to. 

, 1888. Tableau des terrains de sddiment. Zurich. 4to. 

MUNIER-CHALMAS, & DE LAPPARENT, A., 1894. Note sur la nomenclature des terrains 

sedimentaires. Bull. Soc. geol. France [3], vol. xxi, pp. 438-88. 

NEAVERSON, E., 1928. Stratigraphical Palaeontology. Chapters xv-xvi. 

NEUMAYR, M., 1870-1. Jurastudien. Jahrb. d.k.k. Reichsanst., vol. xx, pp. 549-58, 

and vol. xxi, pp. 297-378. 

ODLING, M., 1915. Correlation and Facies of the Upper and Middle Oolites in England 

and North-West France. Proc. Yorks. Geol, Soc,, N.S., vol. xix, pp. 272-87. 

OPPEL, A., 1856-8. Die Juraformation Englands, Frankreichs und des Siidwestlichen 

Deutschlands. 

ORBIGNY, A. D\, 1842-9. Paleontologie franchise; Terrains jurassiques, vol. i. 

1 I am indebted to Dr. C. D. Sherborne for the information that K. (or C.) Mayer and 

C. D. W. Mayer-Eymar, often indexed separately, were one and the same man.

CORRELATION AND CLASSIFICATION 625 

PHILLIPS, J., 1844. Memoirs of William Smith, LL.D. London. 

POMPECKJ, J. F., 1914. Die Bedeutung des Swabischen Jura fur die Erdgeschichte. 

Stuttgart. 

PRUVOST, P., & PRINGLE, J., 1924. A Synopsis of the Geology of the Boulonnais, 

including a Correlation of the Mesozoic Rocks with those of England. P.G.A., vol. 

xxxv, pp. 29-56. 

QUENSTEDT, F. A., 1856-8. Der Jura. Tubingen. 

RAMSAY, A. C., 1864. The Breaks in Succession of the British Mesozoic Strata. 

Q.J.G.S., vol. xx, pp. 40-60. 

RENEVIER, E., 1897. Chronographe geologique: II E edit, du Tableau des terrains 

sedimentaires, suivi d'un Repertoire stratigraphique polyglotte. Comptes rendus, 

Congres geol. int., Session iv (1894), Zurich, 1897, pp. 523-695. 

ROBERTS, T., 1887. On the Correlation of the Upper Jurassic Rocks of the Swiss Jura 

with those of England. Q.J.G.S., vol. xliii, pp. 229-69. 

SALFELD, H., 1913. Certain Upper Jurassic Strata of England. Q.J.G.S., vol. lxix, 

PP.423-32. 

, 1914. Die Gliederung des Oberen Jura in Nordwest-Europa. Neues Jahrb. 

fur Min., &c., Beil.-Bd. xxxvii, pp. 125-246. 

—•—•, 1922. Formanderung und Vererbung bei fossilen Evertebraten [and application 

to zonal work]. Palaeontologische Zeitschrift, vol. iv, pp. 107-12. 

SCHUCHERT, C., 1916. Correlation and Chronology in Geology on the Basis of Paleogeography. 

Bull. Geol. Soc. America, vol. xxvii, pp. 491-514. 

SCUPIN, H., 1923. Der chronologische Wert der Leitfossilien. Centralblatt fur Min., 

&c., 1923, pp. 433-47. 

SEDGWICK, A., I 826. On the Classification of the Strata which appear on the Yorkshire 

Coast. Ann. Phil. [2], vol. xi, pp. 339-62. 

SHEPPARD, T., 1915. William Smith: His Maps and Memoirs. Proc. Yorks. Geol. 

Soc., N.S., vol. xix, pp. 75-254. 

SMITH, J. PERRIN, 1895. Geologic Study of Migration of Marine Invertebrates. 

Journ. Geol. Chicago, vol. iii, pp. 481-95. 

, 1900. Principles of Palaeontologic Correlation. Journ. Geol. Chicago, vol. viii, 

PP- 673-97- 

SMITH, W., 1816-19. Strata identified by Organized Fossils. London. 

, 1817. Stratigraphical System of Organized Fossils. London. 

SPATH, L. F., 1923. Note on the Upper Limit of the Jurassic; in Ammonites from New 

Zealand; Appendix to Trechmann. Q.J.G.S., vol. lxxix, pp. 303-8. 

, 1931. On the Contemporaneity of Certain Ammonite Beds [in the Lower Lias] 

in England and France. Geol. Mag., vol. lxviii, pp. 182-6. 

STAMP, L. D., 1925. Some Practical Aspects of Correlation: a Criticism. P.G.A., 

vol. xxxvi, pp. 11-25. 

STRUCKMANN, C., 1881. Ueber den Parallelismus der hannoverschen und der 

englischen oberen Jurabildungen. Neues Jahrb. fur Min., &c., vol. ii, pp. 77-192. 

Translation by W. S. Dallas, Geol. Mag. [2], vol. viii, pp. 546-57. 

TRUEMAN, A. E., 1923. Some Theoretical Aspects of Correlation. P.G.A., vol. xxxiv, 

pp.193-206. 

WAAGEN, W., 1865. Versuch einer allgemeinen Classifikation der Schichten des oberen 

Jura. Miinchen. 

WEDEKIND, R., 1916. Uber die Grundlagen und Methoden der Biostratigraphie. 

, 1918. t)ber Zonenfolge und Schichtenfolge. Centralblatt fur Min., &c., 1918, 

pp. 268-84. 

WETZEL, W., 1924. Beitrage zur Stratigraphie des Mittleren Doggers von Nordwesteuropa. 

Palaeontographica, vol. lxv, pp. 155-246. 

WILLIAMS, H. S., 1893. The Making and Elements of the Geological Time-Scale. 

Journ. Geol., Chicago, vol. i, pp. 180-96, and 283-95. 

, 1894. Dual Nomenclature in Geological Classification. Journ. Geol., Chicago, 

vol. ii, pp. 145-60. 

, 1901. The Discrimination of Time-Values in Geology. Journ. Geol., Chicago, 

vol. ix, pp. 570-85. 

, 1905. Bearing of some New Paleontologie Facts on Nomenclature and Classification 

of Sedimentary Formations. Bull. Geol. Soc. Amer., vol. xvi, pp. 137-5°-


WILLIAMS, H. S., 1913. Correlation Problems suggested by a Study of the Faunas of 

the Eastport Quadrangle, Maine. Bull. Geol. Soc. America, vol. xxiv, pp. 377-98. 

WILLIAMSON, W. C., 1837. On the Distribution of Fossil Remains on the Yorkshire 

Coast, from the Lower Lias to the Bath Oolite inclusive. Trans. Geol. Soc. [2], 

vol. v, pp. 223-42, and Proc. Geol. Soc., vol. ii, pp. 82-3, 429-32. 

, 1842. On the Distribution of Fossil Remains on the Yorkshire Coast, from the 

Upper Sandstone to the Oxford Clay, inclusive. Trans. Geol. Soc. [2], vol. vi, 

pp. 143-52, and Proc. Geol. Soc., vol. ii, pp. 671-2. 

WOODWARD, H. B., 1892. On Geological Zones. P.G.A., vol. xii, pp. 295-315. 

WRIGHT, T., 1872. On the Correlation of the Jurassic Rocks in the Department of 

the Cote-d'Or, France, with the Oolitic Formations in the Counties of Gloucester 

and Wilts. Proc. Cots. N.F.C., vol. v, pp. 143-238. 

UNDERGROUND STRUCTURE AND DEEP BORINGS 

ARBER, E. A. N., 1916. The Concealed Oxfordshire Coalfield. Trans. Inst. Mining 

Eng., vol. 1, pp. 373-84- 

BURR, M., 1913. Ten Deep Borings in East Kent. Colliery Guardian, vol. xvi, 

PP- 731-4- 

CANTRILL, T. C., & PRINGLE, J., 1914. On a Boring for Coal at Hemington [near 

Radstock], Somerset. Sum. Prog. Geol. Surv. for 1913, pp. 98-101. 

Cox, A. H., 1919. Report on Magnetic Disturbances in Northants and Leicestershire, 

and their Relations to Geological Structure. Phil. Trans. Royal Soc., vol. ccxix A, 

PP- 73-135- 

DAVIES, A. M., & PRINGLE, J., 1913. On two Deep Borings at Calvert Station 

(North Bucks.) and on the Palaeozoic Floor north of the Thames. Q.J.G.S., 

vol. lxix, pp. 308-42. 

DAWKINS, W. BOYD, 1894. The Probable Range of the Coal Measures under the 

Newer Rocks of Oxfordshire and the Adjoining Counties. Geol. Mag. [4], vol. i, 

PP- 459-62; Rept. Brit. Assoc. for 1894, pp. 646-7. 

, 1913. The South-Eastern Coalfield, the Associated Rocks, and the Buried Plateau. 

Trans. Inst. Mining Eng., vol. xliv, pp. 350-78. 

DEWEY, H., PRINGLE, J., & CHATWIN, C. P., 1925. Some Recent Deep Borings in the 

London Basin. Sum. Prog. Geol. Surv. for 1924, pp. 127-37. 

EDWARDS, W., & PRINGLE, J., 1926. On a Borehole in Lower Oolitic Rocks at Wincanton, 

Somerset [Bridport Sands to Kellaways Beds]. Sum. Prog. Geol. Surv. for 1925, 

PP- 183-8. 

EUNSON, H. J., 1886. Notes on the Deep Boring at Orton, near Kettering, Northants. 

Journ. Northants N.H.S., vol. iv, pp. 57-68. 

GIBSON, W., 1918. On a Deep Boring near Market Weighton. Sum. Prog. Geol. 

Surv. for 1917, pp. 42-5. 

GODWIN-AUSTEN, R. A. C., 1856. On the Possible Extension of the Coal-Measures 

beneath the South-Eastern Part of England. Q.J.G.S., vol. xii, pp. 38-73. 

GOSSELET, J., 1898. ^tude preliminaire des r£cents sondages faits dans le Nord de 

la France pour la recherche du bassin houiller. Ann. Soc. g6ol. Nord, vol. xxvii, 

PP- I 39~49- English transl. Trans. Inst. Mining Eng., vol. xviii, 1899-1900, pp. 

3I7-25- 

HULL, E., i860. On the South-Easterly Attenuation of the Lower Secondary Formations 

of England; and the probable Depth of the Coal Measures under Oxfordshire 

and Northamptonshire. Q.J.G.S., vol. xvi, pp. 63-81. 

JUDD, J. W., 1884. On the Nature and Relations of the Jurassic Deposits which 

underlie London; with an Introductory Note on a Deep Boring at Richmond, 

Surrey, by C. Homersham. Q.J.G.S., vol. xl, pp. 724-64, and Nature, vol. xxix, 

P- 329. 

JUKES-BROWNE, A. J., 1889. The Occurrence of Granite in a Boring at Bletchley 

[supposedly in the Kellaways Rock, more probably at the base of the Lias]. Geol. 

Mag. [3], vol. vi, pp. 356-61. [For more recent interpretation see Morley Davies, 

Q.J.G.S., 1913, pp. 332-3J 

, 1891. On a Boring at Shillingford near Wallingford. Midland Naturalist, 

vol. xiv, pp. 201-8.

DEEP BORINGS 627 

JUKES-BROWNE, A. J., 1893. On Some Recent Borings through the Lower Cretaceous 

Strata in East Lincolnshire. Q.J.G.S., vol. xlix, pp. 467-77. 

LAMPLUGH, G. W., 1917. The Underground Range of the Jurassic and Lower 

Cretaceous Rocks in East Kent. Sum. Prog. Geol. Surv. for 1916, pp. 45-52. 

, 1917. On a Deep Boring made in 1907-9 at Battle [Purbeck and Portland Beds 

and Kimeridge Clay]. Sum. Prog. Geol. Surv. for 1916, pp. 40-4. 

LAMPLUGH, G. W., & KITCHIN, F. L., 191 I. The Mesozoic Rocks in some of the Coal 

Explorations in Kent. Mem. Geol. Surv. 

LAMPLUGH, G. W., KITCHIN, F. L., & PRINGLE, J., 1923. The Concealed Mesozoic 

Rocks in Kent. Mem. Geol. Surv. 

LEMOINE, P., 1910. Resultats geologiques des sondages profonds du bassin de Paris. 

Bull. Soc. industr. miner., May 1910, p. 367. 

, 1930. Considerations sur la structure d'ensemble du bassin de Paris. Livre 

Jubilaire, Cent. Soc. geol. France, vol. ii, pp. 481-98. 

PRESTWICH, J., 1856. On a Boring through the Chalk at Kentish Town, London. 

Q.J.G.S., vol. xii, pp. 6-14. 

PRESTWICH, J., & MOORE, C., 1878. On the Section of Messrs. Meux & Co.'s Artesian 

Well in the Tottenham Court Road .. . and on the Probable Range of the ... [Palaeozoic 

Rocks under London]. Q.J.G.S., vol. xxxiv, pp. 902-23. 

PRINGLE, J., 1917. On Deep Borings for Coal and Ironstone at Bere Farm, Elham and 

Folkestone, Kent. Palaeozoic Rocks only. Sum. Prog. Geol. Surv. for 1916, 

pp. 34-40- 

, 1922. On a Boring for Coal at Westbury, Wiltshire. Sum. Prog. Geol. Surv. for 

1921, pp. 146-53. 

, 1923. On the Concealed Mesozoic Rocks in South-West Norfolk. Sum. Prog. 

Geol. Surv. for 1922, pp. 126-39. 

, 1929. Note on a Deep Boring (No. 4) at the Waterworks, Tetbury, Gloucestershire. 

Proc. Cots. N.F.C., vol. xxiii, pp. 187-90. [Upper Lias-Great Oolite.] 

PRUVOST, P., 1928. Le sondage de Ferrieres-en-Bray. Ann. de TOffice nation, des 

Combustibles liquides, 3 e annee, 3 e livr., pp. 429-57; and Comptes rendus Acad. 

Sciences, vol. clxxxci, 1928, pp. 242, 386. 

RASTALL, R. H., 1926. Note on the Geology of the Bath Springs. Geol. Mag., 

vol. lxiii, pp. 98-104. 

, 1927. The Underground Structure of Eastern England. Geol. Mag., vol. Ixiv, 

pp. 10-26. 

RICHARDSON, L., 1914-21. Deep Borings at: Kemble, Chavenage near Tetbury, 

Wallsworth Hall near Gloucester, at Gloucester, Shipton Moyne near Tetbury, and 

Tetbury Waterworks. Proc. Cots. N.F.C., vol. xviii, pp. 185, 243, 247, 250, and 

vol. xix, pp. 49, 57, and vol. xx, p. 151. 

STRAHAN, A., 1912. On a Deep Boring for Coal at Ebbsfleet, near Ramsgate [Palaeozoic 

Rocks]. Sum. Prog. Geol. Surv. for 1911, pp. 34-40. 

, 1913. The Form and Structure of the Palaeozoic Platform on which the Secondary 

Rocks of England rest [with complete list of deep borings]. Q.J.G.S., 

vol. lxix, pp. lxx-xci. 

, 1913. Boring at the East Anglian Ice Co.'s Works, Lowestoft. Sum. Prog. Geol. 

Surv. for 1912, pp. 87-8. 

, 1913. Batsford (or Lower Lemington) Boring, near Moreton in Marsh. Sum. 

Prog. Geol. Surv. for 1912, pp. 90-1. 

, 1916. On a Deep Boring for Coal near Little Missenden, in Buckinghamshire. 

Sum. Prog. Geol. Surv. for 1915, pp. 43-6. 

THOMPSON, B., 1890. The Bletchley Boring. Journ. Northants N.H.S., vol. v, 

pp. 20-5. 

WHITAKER, W., 1889. On the Extension of the Bath Oolite under London, as shown 

by a Deep Boring at Streatham. Rept. Brit. Assoc. for 1888, p. 656. 

WOODWARD, H. B., 1886. Account of a Weil-Sinking made by the Great Western 

Railway Co. at Swindon, with lists of Fossils by E. T. Newton [Kim. Clay-Forest 

Marble]. Q.J.G.S., vol. xlii, pp. 287-308.


CONTEMPORANEOUS TECTONICS AND SEDIMENTATION 

ANDREE, K., 1908. Ober stetige und unterbrochene Meeressedimentation, ihre 

Ursachen, sowie iiber deren Bedeutung fur die Stratigraphie. Neues Jahrb. fur 

Min., &c., B.-B. xxv, pp. 366-421. 

BEILBY, E. M., 1930. The Market Weighton Axis in Middle Jurassic Times. Trans. 

Leeds Geol. Assoc., xx, pp. 10-12. 

BERTRAND, M., 1893. Sur la continuite du phenomene de plissement dans le bassin 

de Paris. Bull. Soc. geol. France [3], vol. xx, pp. 118-65. 

BEURLEN, K., 1927. Stratigraphische Untersuchungen in Weissen Jura Schwabens, 

Neues Jahrb. fur Min., &c., B.-B. Ivii, pp. 78-124, 161-230. 

BRINKMANN, R., 1925. Ober die sedimentare Abbildung epirogener Bewegungen, 

sowie iiber das Schichtungsproblem. Nachr. Gesell. Wissensch. Gottingen, 

Math.-nat. Klas., pp. 202-28. 

Cox, A. H., & TRUEMAN, A. E., 1920. Intra-Jurassic Movements and the Underground 

Structure of the Southern Midlands. Geol. Mag., vol. Ivii, pp. 198-208. 

DAHLGRON, F., 1921. Tektonische, insbesondere kimmerische Vorgange im mittleren 

Leinegebiet. Jahrb. Preuss. Geol. Landesanst., vol. xlii, pp. 723-64. 

DAVIES, A. M., 1929. Morphology; England and Wales. Handbook of the Geology 

of Great Britain, ch. i, pp. 1-4. 

FREBOLD, H., 1925. Ober cyclische Meeressedimentation. Leipzig. 

, 1926. Zur Frage der epirogenen Bewegungen im unteren Jura Mesoeuropas und 

der fur ihre Ableitung wichtigen stratigraphischen Unterlagen. Centralblatt fur 

Min., &c., B., 1926, pp. 73-8. 

, 1927. Die palaogeographische Analyse der epirogenen Bewegungen und ihre 

Bedeutung fur die Stratigraphie. Geol. Arch., 4 Jahrg., pp. 223-40. 

GRACHT, W. A. M. VAN W. VAN DER, 1913. Proeve eener Tektonische Schetskaart van 

het Belgisch-Nederlandsch-Westfaalsche Kolenveld en hetaangrenzende noordelijke 

Gebied tot aan de breedte van Amsterdam. Jaarverslag der Rijkopsporung van 

Delfstoffen over 1913. Amsterdam. 

GRUPE, O., 1926. Die Einzelphasen der saxonischen Gebirgsbildung am Deister. 

Jahrb. Preuss. Geol. Landesanst., vol. xlvii, pp. 357-82. 

HAUG, E., 1900. Les geosynclinaux et les aires continentales. Bull. Soc. geol. France 

[3L vol. xxviii, pp. 617-711. 

HAWKINS, H. L., 1918. Notes on the Geological Structure of the Vale of Kingsclere. 

Proc. Hampshire F.C., vol. viii, part ii, pp. 191-212. 

KENDALL, P. F., 1905. Sub-Report on the Concealed Portion of the Coalfield of 

Yorkshire, Derbyshire and Nottinghamshire [with table of borings]. Final Report 

of the Royal Commission on Coal Supplies, Part IX, Appendix 3, pp. 188-205 

(18-35). 

KLUPFEL, W., 1916. Uber die Sedimente der Flachsee im Lothringer Jura. Geol. 

Rundschau, vol. vii, pp. 97-109. 

, 1926. Beziehungen zwischen Tektonik, Sedimentation und Palaogeographie in 

der Weser-Erzformation des Ober-Oxford. Zeitschr. Deutsch. Geol. Gesell., 

vol. lxxviii, pp. 178-92. 

LAMPLUGH, G. W., 1919. The Structure of the Weald and Analogous Tracts. 

Q.J.G.S., vol. Ixxv, pp. lxxiii-xcv. 

, 1920. On Differential Earth Movement in North-East Yorkshire during the 

Jurassic Period. Proc. Yorks. Geol. Soc., N.S., vol. xix, pp. 383-94. 

MOLENGRAAFF, G. A. F., & GRACHT, W. A. M. VAN W. VAN DER, 1913. Tektonik und 

Bau des posttriadischen Mesozoikums in den Niederlanden. In 'Niederlande'; 

Handb. Reg. Geol., vol. i, Abt. 3, pp. 33-6. 

PHILIPPI, E., 1908. Ober das Problem der Schichtung und iiber Schichtbildung am 

Boden der heutigen Meere. Zeitschr. Deutsch. Geol. Gesell., vol. lx, pp. 346-77. 

PRUVOST, P., 1930. Sedimentation et Subsidence. Livre jubilaire, Soc. geol. France, 

vol. ii, pp. 545-64. 

RASTALL, R. H., 1925. On the Tectonics of the Southern Midlands. Geol. Mag., 

vol. lxii, pp. 193-222. 

STILLE, H., 1902. tJber pracretacische Schichtcnverschiebungen im alteren Meso-

TECTONICS 629 

zoikum des Egge-Gebirges. Jahrb. Preuss. Geol. Landesanst., vol. xxiii, pp. 296- 

322. 

STILLE, H., 1905. Uber Strandverschiebungen in hannoverschen oberen Jura. 

Zeitschr. Deutsch. Geol. Gesell., vol. lvii, Monatsber., pp. 515-34. 

, 1905. Zur Kenntniss der Dislokationen, Schichtenabtragungen und Transgressionen 

im jiingsten Jura und der Kreide Westfalens. Jahrb. Preuss. Geol. 

Landesanst., vol. xxvi, pp. 103-25. 

, 1910. Senkungs-, Sedimentations- und Faltungsraume. Compte rendu, 

Congres g£ol. int., Session ix, Stockholm, pp. 819-36. 

, 1913. Die saxonische 'Faltung'. Zeitschr. Deutsch. Geol. Gesell., vol. lxv, 

Monatsber., pp. 575~93- 

, 1913. Die Kimmerische (vorcretacische) Phase der saxonischen Faltung des 

deutschen Bodens. Geol. Rundschau, vol. iv, pp. 362-83. 

, 1922. Studien uber Meeres- und Bodenschwankungen. Nachrichten kgl. 

Gesell. Wiss. Gottingen, M.P. Klasse, pp. 83-95. 

, 1924. Grundfragen der vergleichenden Tektonik. Berlin. 

STRAHAN, A., 1904. [Discrimination of Periods of Earth-Movement in the British 

Isles.] Rept. Brit. Ass. for 1904, Pres. Address Section C; reprinted Geol. Mag. 

[5], vol. i, 1904, pp. 449-62. 

TOPLEY, W., 1874. On the Correspondence between some Areas of Apparent Upheaval 

and the Thickening of Subjacent Beds. Q.J.G.S., vol. xxx, pp. 186-95. 

TWENHOFEL, W. H., 1926. Treatise on Sedimentation. London. [See review, Geol. 

Mag. 1927, vol. lxiv, pp. 180-4.] 

, 1931. Environment in Sedimentation and Stratigraphy. Bull. Amer. Geol. 

Soc., vol. xlii, pp. 407-24, 

VAUGHAN, T. W., SCHUCHERT, C., and others, 1920. Researches on Sedimentation. 

Bull. Amer. Geol. Soc., vol. xxxi, pp. 401-32. 

VERSEY, H. C., 1929. The Tectonic Structure of the Howardian Hills and Adjacent 

Areas. Proc. Yorks. Geol. Soc., N.S., vol. xxi, pp. 197-227. 

, 1931. Saxonian Movements in East Yorkshire and Lincolnshire. Proc. Yorks. 

Geol. Soc., N.S., vol. xxii, pp. 52-8. 

GENERAL WORKS, ON BRITAIN AS A WHOLE AND ON CERTAIN 

DISTRICTS 

ARKELL, W. J., 1929. Jurassic; Encyclopaedia Britannica, ed. xiv, vol. xiii, pp. 193-6. 

BARRETT, C., 1878. The Geology of Swyre, Puncknowle, Burton Bradstock, Loders, 

Shipton Gorge, Litton Cheney, Longbredy, Littlebredy and Abbotsbury, Dorset. 

8vo, Bridport. 

BEESLEY, T., 1877. The Geology of the Eastern Portion of the Banbury and Cheltenham 

Direct Railway [Upper Lias to Great Oolite]. P.G.A., vol. v, pp. 165-85. 

BONNEY, T. G., 1872. Cambridgeshire Geology. Cambridge. 

BOSWELL, P. G. H., 1917. Rhaetic and Jurassic of Scotland. Handb. Reg. Geol., 

vol. iii, pp. 211-12, 233-4. 

BRYCE, J., & ARMSTRONG, J., 1876. The Jurassic Strata of Skye and Raasay: with 

List of the Jurassic Fossils of Skye, Raasay and Mull. In 'Catalogue of the Western 

Scottish Fossils'. Glasgow. 

BRYCE, J., & TATE, R., 1873. On the Jurassic Rocks and Palaeontology of Skye and 

Raasay. Q.J.G.S., vol. xxix, pp. 317-51. 

BUCKLAND, W., & DE LA BECHE, H. T., 1835. On the Geology of the Neighbourhood 

of Weymouth and the adjacent parts of the Coast of Dorset. Trans. Geol. Soc. [2], 

vol. iv, pp. 1-46. 

BUCKMAN, J., 1843. Geological Chart of the Oolitic Strata of the Cotteswold Hills, 

and the Lias of the Vale of Gloucester. Folio, Cheltenham. 

, 1858. On the Oolite Rocks of Gloucestershire and North Wilts. Q.J.G.S., 

vol. xiv, pp. 98-103. 

CROSS, J. E., 1875. The Geology of North-West Lincolnshire. Q.J.G.S., vol. xxxi, 

pp.115-30. 

DAMON, R., I860. Geology of Weymouth and the coast of Dorset, and Supplement 

(with 11 plates of fossils).


DAVIES, A. M., 1909. Buckinghamshire: in Geology in the Field, vol. i, ch. vi, 

pp. 179^91. 

, 1917-29. Jurassic; England and Wales, Handb. Reg. GeoL^yol. iii, pp. 213- 

45. Re-written in Handbook to Geol. Great Britain, 1929. 

DAVIS, J. W., 1892. On Some Sections in the Liassic and Oolitic Rocks of Yorkshire. 

Proc. Yorks. Soc., vol. xii, Lias, pp. 170-89; Oolites (Lower-Upper), pp. 189-214. 

DOUGLAS, J. A., 1909. The Oxford and Banbury District: in Geology in the Field, 

vol. i, ch. vii, pp. 192-209. 

FEARNSIDES, W. G., 1904. The Geology of Cambridgeshire. In Marr and Shipley's 

Handbook to the Natural History of Cambridgeshire, pp. 9-50. Cambridge. 

FOX-STRANGWAYS, C., 1892. The Jurassic Rocks of Britain, vol. i, Yorkshire. Mem. 

Geol. Survey. 

GEIKIE, A., 1858. On the Geology of Strath, Skye; and Notes on the Fossils from 

the Lias of the Isles of Pabba, Scalpa and Skye, by T. Wright. Q.J.G.S., vol. xiv, 

pp. 1-36. 

HERRIES, R. S., 1906. The Geology of the Yorkshire Coast between Redcar and Robin 

Hood's Bay. P.G.A., vol. xix, pp. 410-45. 

, 1910. East Yorkshire: in Geology in the Field, vol. iii, pp. 592-623. 

HUDLESTON, W. H., & MONCKTON, H. W., 1910. Dorset: in Geology in the Field, 

vol. ii, pp. 365-413. 

IBBETSON, L. L. B., 1848. Notice of the Geology of the Neighbourhood of Stamford 

and Peterborough [Upper Lias-Oxford Clay]. Rept. Brit. Assoc. for 1847, pp. 127-31. 

JUDD, J. W., 1873-8. The Secondary Rocks of Scotland. 

I. [Introduction and East Coast]. Q.J.G.S., vol. xxix, pp. 97-197 (1873). 

II. On the Ancient Volcanoes of the Highlands and the Relations of their Products 

to the Mesozoic Strata. Ibid., vol. xxx, pp. 220-301 (1874). 

III. The Strata of the Western Coast and Islands. Ibid., vol. xxxiv, pp. 660-743 

(1878). 

JUKES-BROWNE, A. J., 1910. Lincolnshire: in Geology in the Field, vol. iii, pp. 488- 

517. 

KENDALL, P. F., & WROOT, H. E., 1924. Geology of Yorkshire. Printed for the authors, 

pp. 1-995. 

LEE, G. W., & BUCKMAN, S. S., 1913. [Palaeontological notes on the Lias, Inferior 

Oolite and Oxford Clay of the Isle of Mull.] Sum. Prog. Geol. Surv. for 1912, 

PP- 74^5, and 35. 

LEE, G. W., 1914. Mesozoic Rocks: West Highland District [Notes on Rhaetic, 

Upper Lias and Great Estuarine Strata of Raasay and Skye]. Sum. Prog. Geol. 

Surv. for 1913, pp. 39-43. 

LEE, G. W., & PRINGLE, J., 1932. A Synopsis of the Mesozoic Rocks of Scotland. 

Trans. Geol. Soc., Glasgow, vol. xix, pp. 158-224. 

LLOYD MORGAN, C., & REYNOLDS, S. H., 1909. Sketch of the Geology of the Bristol 

District. Proc. Bristol Nat. Soc. [4], vol. ii, pp. 5-26. 

LONSDALE, W., 1832. On the Oolitic District of Bath. Trans. Geol. Soc. [2], vol. iii, 

pp. 241-76. 

LYCETT, J., 1857. The Cotteswold Hills. Handbook introductory to their Geology 

and Palaeontology, London. [Inferior Oolite-Cornbrash.] 

MANSEL-PLEYDELL, J. C., 1873. A Brief Memoir on the Geology of Dorset. Geol. 

Mag., vol. x, pp. 402-13, 438-47. 

MORRIS, J., 1853. On Some Sections in the Oolitic District of Lincolnshire. Q.J.G.S., 

vol. ix, pp. 317-44. [Inferior Oolite-Oxford Clay.] 

, 1869. Geological Notes on Parts of Northampton and Lincolnshire. Geol. 

Mag., vol. vi, pp. 99-105. [Upper Lias-Great Oolite.] 

MURCHISON, R. 1, 1827-8. On the Coalfield of Brora, Sutherlandshire, and some 

other Stratified Deposits in the North of Scotland. Trans. Geol. Soc. [2], vol. ii, 

pp. 293-326, and Supplementary Remarks on the Strata of the Oolitic Series . . . 

in the Counties of Sutherland and Ross, and in the Hebrides, Ibid., pp. 353-68. 

, 1834-45. Outline of the Geology of the Neighbourhood of Cheltenham, 1834. 

2nd edition, with palaeontological appendix by J. Buckman, 1845. 

PHILLIPS, J., 1829. Illustrations of the Geology of Yorkshire, part i: The Yorkshire 

Coast.

GENERAL WORKS 631 

PHILLIPS, J., 1855. The Neighbourhood of Oxford and its Geology. Oxford Essays 

for 1855. 8vo, Oxford. 

, 1858. On Some Comparative Sections in the Oolitic and Ironstone Series of 

Yorkshire [Mid. Lias-Kim. Clay]. Q.J.G.S., vol. xiv, pp. 84-98. 

, 1871. Geology of Oxford and the Valley of the Thames. Oxford. 

PORTER, H., 1861. The Geology of Peterborough and its Vicinity. Peterborough. 

RASTALL, R. H., 1909. Cambridgeshire, Bedfordshire and West Norfolk: in Geology 

in the Field, vol. i, ch. v, pp. 124-78. 

REYNOLDS, S. H., & VAUGHAN, A., 1902. On the Jurassic Strata cut through by the 

South Wales Direct Line between Filton and Wootton Bassett [Rhaetic-Corallian]. 

Q.J.G.S., vol. lviii, pp. 719-52. 

RICHARDSON, L., 1910. The Neozoic Rocks of Gloucestershire and Somerset: in 

Geology in the Field, vol. ii, pp. 329-64. 

SCROPE, G. P., 1859. Geology of Wiltshire. Wilts. Arch. N.H. Mag., vol. v, 

pp.89-113. 

SEDGWICK, A., 1846. On the Geology of the Neighbourhood of Cambridge, including 

the Formations between the Chalk and the Great Bedford Level. Rept. Brit. 

Assoc. for 1845, Sections, p. 40. 

SOLLAS, W. J., 1926. The Geology of the County round Oxford, in 'The Natural 

History of the Oxford District*, edited by J. J. Walker, pp. 32-59. Oxford. 

THOMPSON, B., 1910. Northamptonshire and Parts of Rutland and Warwickshire: in 

Geology in the Field, vol. iii, pp. 450-87. 

VERNON, W., 1826. An Account of the Strata North of the Humber, near Cave. Ann. 

Phil. [2], vol. xi, pp. 435-9. 

WALCOTT, J., 1799. Descriptions and Figures of Petrifications found in the Quarries, 

Gravel-Pits, &c. near Bath. Hazard, Bath. 

WEBSTER, T., 1816. Geological Observations on the Isle of Wight and Adjacent Coast 

of Dorsetshire [written 1811-12]; in Englefield, H., 1816. Description of the Principal 

Picturesque Beauties, &c., of the Isle of Wight, pp. 117-238. [Kimeridge Clay- 

Purbeck Beds.] 

WEDD, C. B., 1902. [Notes on the Jurassic Rocks—Lower Lias-Corallian—of Skye.] 

Sum. Prog. Geol. Surv. for 1901, pp. 142-4. 

WHITE, H. J. O., 1910. Berkshire and Part of the Thames Valley: in Geology in the 

Field, vol. ii, pp. 210-35. 

WITCHELL, E., 1882. The Geology of Stroud and the Area Drained by the Frome. 

Stroud [Lower Lias-Forest Marble.] 

WOODWARD, H. B., 1893-5. The Jurassic Rocks of Britain (Yorkshire excepted): 

vol. iii, The Lias of England and Wales (1893); vol. iv, Lower Oolitic Rocks of 

England (1894); vol. v, Middle and Upper Oolitic Rocks (1895). Mems. Geol. Surv. 

, 1897. Geology of the London Extension of the Manchester, Sheffield, and 

Lincolnshire Railway. Part II: Rugby to Quainton Road, near Aylesbury. Geol. 

Mag. [4], vol. iv, pp. 97-105. 

, 1899. South Wales Direct Railway [Notes on Rhaetic-Corallian, Filton to 

Wootton Bassett]. Sum. Prog. Geol. Surv. for 1898, pp. 188-92. 

, 1910. Wiltshire: in Geology in the Field, vol. ii, pp. 293-307. 

YOUNG, G., & BIRD, J., 1822. A Geological Survey of the Yorkshire Coast: describing 

the strata and fossils occurring between the Humber and the Tees, from the German 

Ocean to the Plain of York. Whitby, 1822; 2nd ed. Whitby, 1828. 

RH7ETIC BEDS 

ADAMS, W., & HARRISON, W. J., 1877. On the Penarth or Rhaetic Beds of Glamorganshire, 

Leicestershire, &c. Trans. Cardiff. Nat. Soc., vol. viii, pp. 96-106 [largely 

reprinted from Harrison, Q.J.G.S., vol. xxxii, 1876, pp. 212-18]. 

BATES, E. F., & HODGES, L., 1886. Notes on a recent Exposure of the Lower Lias and 

Rhaetics in the Spinney Hills, Leicester. Trans. Lit. and Phil. Soc. Leicester [2], 

parti, pp. 22-3. 

BATHER, F. A., 1909-10. Fossil Representatives of the Lithodomous Worm, Polydora 

[at the base of the Rhsetics]; and Some Fossil Annelid Burrows. Geol. Mag. [5], 

vol. vi, pp. 108-10, and vol. vii, pp. 114-16.


BRISTOW, H. B., 1864. On the Rhaetic or Penarth Beds of the neighbourhood of 

Bristol and the South-West of England. Geol. Mag., vol. i, p. 236; and Rept. 

Brit. Assoc. for 1864 (1865), p. 50. 

BRODIE, P. B., 1874. Notes on a Railway-section of the Lower Lias and Rhaetics 

between Stratford-on-Avon and Fenny Compton, &c. Q.J.G.S., vol. xxx, 

pp. 746-9. 

, 1886. On two Rhaetic Sections in Warwickshire. Q.J.G.S., vol. xlii, pp. 272-5. 

, 1888. On the Range, Extent and Fossils of the Rhaetic Formation in Warwickshire. 

Proc. Warwicks. N.F.C. for 1887, p. 19. 

BROWNE, M., 1893-6. Vertebrate Remains from the Rhaetic Beds of Britain. Rept. 

Brit. Assoc. 1893, pp. 748-9; 1894, pp. 657-8; 1894 (and Rhaetic Bone Bed of Aust 

Cliff, &c.), pp. 804-5. 

BURTON, F. M., 1867. On the Rhaetic Beds near Gainsborough. Q.J.G.S., vol. xxiii, 

pp. 315-22. 

CALLAWAY, C., 1901. The Pre-Rhaetic Denudation of the Bristol Area. Proc. Cots. 

N.F.C., vol. xiv, pp. 47-58. 

COLE, G. A. J., 1917. Rhaetic; Ireland. In Handb. Reg. Geol., British Isles, p. 212. 

DAVIS, J. W., 1881. Notes on the Fish-Remains of the Bone Bed at Aust. Q.J.G.S., 

vol. xxxvii, pp. 414-25. 

DAWKINS, W. B., 1864. On the Rhaetic Beds and White Lias of Western and Central 

Somerset, &c. Q.J.G.S., vol. xx, pp. 396-412. 

ETHERIDGE, R., 1865. On the Rhaetic or Avicula contorta Beds at Garden Cliff, 

Westbury-upon-Severn. Proc. Cots. N.F.C., vol. iii, pp. 218-34. 

, 1872. On the Physical Structure and Organic Remains of the Penarth (Rhaetic) 

Beds of Penarth and Lavernock; with description of thfe Westbury-on-Severn 

Section (with Plates). Trans. Cardiff Nat. Soc., vol. iii, pp. 39-64. 

GRONWALL, K. A., 1906. On the Occurrence of the [Lamellibranch] Genus Dimyodon 

Mun. Chalm. in the Mesozoic [Rhaetic] Rocks of Great Britain. Geol. Mag. [5], 

vol. iii, pp. 202-5. 

HARRIS, T. M., 1931. Rhaetic Floras. Biological Reviews and Proc. Cambridge Phil. 

Soc., vol. vi, pp. 133-62. 

HARRISON, W. J., 1876. On the Occurrence of the Rhaetic Beds in Leicestershire. 

Q.J.G.S., vol. xxxii, pp. 212-18. 

HOWARD, F. T., 1895. The Geology of Barry Island. Trans. Cardiff Nat. Soc., 

vol. xxvii, pp. 42-55. 

, 1897. Notes on the Base of the Rhaetic Series at Lavernock Point. Trans. 

Cardiff Nat. Soc., vol. xxix, pp. 64-6. 

, 1899. The Geology of the Cowbridge District. Trans. Cardiff Nat. Soc., 

vol. xxx, pp. 36-47. 

JONES, T. R., 1894. On the Rhaetic and some Liassic Ostracoda of Britain. Q.J.G.S., 

vol. 1, pp. 156-68. 

MISKIN, F. F., 1922. The Triassic Rocks [including Rhaetic] of South Glamorgan. 

Trans. Cardiff Nat. Soc., vol. Iii, pp. 17-25 and plates. 

NEWTON, E. T., 1899. On a Megalosauroid Jaw from Rhaetic Beds near Bridgend, 

Glamorganshire. Q.J.G.S., vol. Iv, pp. 89-96. 

PARIS, E. T., 1906. Additional Notes on the Denny-Hill [Rhaetic] Section near Minsterworth, 

Gloucestershire. Proc. Cots. N.F.C., vol. xv, pp. 263-6. 

PEACH, B. N., GUNN, W., & NEWTON, E. T., 1901. On a remarkable Volcanic Vent 

of Tertiary Age in the Island of Arran, enclosing Mesozoic Fossiliferous Rocks 

[Rhaetic and Lower Lias]. Q.J.G.S., vol. Ivii, pp. 226-43. 

RAMSAY, A. C., 1871. On the Physical Relations of the New Red Marl, Rhaetic Beds 

and Lower Lias. Q.J.G.S., vol. xxvii, pp. 189-99. 

REYNOLDS, S. H., & VAUGHAN, A., 1904. The Rhaetic Beds of the South-Wales Direct 

Line. Q.J.G.S., vol. Ix, pp. 194-214. 

RICHARDSON, L., 1903. The Rhaetic Rocks of North-West Gloucestershire. Proc. 

Cots. N.F.C., vol. xiv, pp. 127-74, and Supplement, pp. 251-7. 

, 1903. Two Sections of the Rhaetic Rocks in Worcestershire. Geol. Mag. [4], 

vol. x, pp. 80-2. 

, 1903. The Rhaetic and Lower Lias of Sedbury Cliff, near Chepstow, Monmouthshire. 

Q.J.G.S., vol. lix, pp. 390-5.

RH/ETIC BEDS 633 

RICHARDSON, L., 1903. Observations on the Rhaetic Rocks of Worcestershire. Trans. 

Worcester Nat. C., vol. iii, part 2, pp. 92-101. 

, 1904. The Evidence for a Non-Sequence between the Keuper and Rhaetic 

Series in North-West Gloucestershire and Worcestershire. Q.J.G.S., vol. lx, 

PP-349-58. 

, 1905. The Rhaetic Rocks of Monmouthshire. Q.J.G.S., vol. Ixi, pp. 374-84. 

, 1905. The Rhaetic and Contiguous Deposits of Glamorganshire. Q.J.G.S., 

vol. Ixi, pp. 385-424. 

, 1905. On the Occurrence of Rhaetic Rocks at Berrow Hill, near Tewkesbury. 

Q.J.G.S., vol. Ixi, pp. 425-30. 

, 1906. On the Rhaetic and Contiguous Deposits of Devon and Dorset. P.G.A., 

vol. xix, pp. 401-9. 

, 1906. On the Occurrence of Ceratodus in the Rhaetic at Garden Cliff, Westburyon-Severn, 

Glouccstershirey with some remarks upon its distribution in British 

Formations. Proc. Cots. N.F.C., vol. xv, pp. 267-70. 

-——, 1909. The Rhaetic Section at Wigston, Leicestershire. Geol. Mag. [5], vol. vi, 

pp. 366-70. [See also A. R. Horwood, Rept. Brit. Assoc. 1911, Portsmouth, p. 388.] 

, 1911. The Rhaetic and Contiguous Deposits of West, Mid, and part of East 

Somerset. Q.J.G.S., vol. lxvii, pp. 1-74. 

, 1912. The Rhaetic Rocks of Warwickshire. Geol. Mag. [5], vol. ix, pp. 24-33. 

, 1917-29. Rhaetic: England and Wales. Handb. Reg. Geol., vol. iii, 1917, 

pp. 207-11. And in Handb. Geol. Great Britain, 1929, pp. 341-6. 

RICHARDSON, L., & TUTCHER, J. W., 1914. On Pteromya crowcombeia Moore, and some 

species of Pleuromya and Volsella from the Rhaetic and Lower Lias. Proc. Yorks. 

Geol. Soc., N.S., vol. xix, pp. 51-8. 

SHORT, A. R., 1903. On the Cotham Marble. Proc. Bristol Nat. Soc., N.S., vol. x, 

pp. 3-54 and Plates. 

, 1904. A Description of some Rhaetic Sections in the Bristol District, with considerations 

on the Mode of Deposition of the Rhaetic Series. Q.J.G.S., vol. lx, 

pp. 170-93. 

SOLLAS, I. B. J., 1901. Structure and Affinities of the Rhaetic Plant, Naiadita. 

Q.J.G.S., vol. Ivii, pp. 307-12. 

STORRIE, J., 1895. Notes on the Tooth of a Species of Mastodonsaurus, found with 

some other bones near Lavernock. Trans. Cardiff Nat. Soc., vol. xxvi, pp. 105-6. 

STRAHAN, A., 1903-4. Cutting on the South Wales Direct Railway, near Chipping 

Sodbury [Rhaetic Beds]. Sum. Prog. Geol. Surv. for 1902, pp. 192-4, and for 1903, 

pp.171-2. 

TATE, R., 1867. On the Liassic affinities of the Avicula contorta Series. Geol. and Nat. 

Hist. Repertory, vol. i, pp. 364-9. 

TAWNEY, E. B., 1866. On the Western Limit of the Rhaetic Beds in South Wales and 

on the position of the Sutton Stone, with a note on the Corals by P. M. Duncan. 

Q.J.G.S., vol. xxii, pp. 68-93. 

THOMPSON, B., 1894. Landscape Marble. Q.J.G.S., vol. 1, pp. 393-410. 

TOMES, R. F., 1884. A Comparative and Critical Revision of the Madreporaria of the 

White Lias of the Middle and Western Counties of England, and of those of the 

Conglomerate at the Base of the South Wales Lias. Q.J.G.S., vol. xl, pp. 353-75. 

, 1903. Description of a Species of Heterastrcea from the Lower Rhaetic of 

Gloucestershire. Q.J.G.S., vol. lix, pp. 403-7. 

WICKES, W. H., 1900. A New Rhaetic Section at [Redland], Bristol. P.G.A., vol. xvi, 

pp. 421-3. Also Proc. Bristol Nat. Soc., N.S., vol. ix, 1901, pp. 99-103; and Additional 

Observations by J. Parsons, ibid., pp. 104-8. 

WILSON, E., 1882. The Rhaetics of Nottinghamshire. Q.J.G.S., vol. xxxviii, 

pp. 451-6. 

, 1891-4. Section of the Rhaetic Rocks at Pylle Hill (Totterdown). Q.J.G.S., 

1891, vol. xlvii, pp. 545-9; and Proc. Bristol Nat. Soc., N.S., vol. vii, 1894, 

pp. 213-31. 

WIN WOOD, H. H., 1876. Notes on a Rhaetic and Lower Lias Section on the Bath and 

Evercreech Line near Chilcompton. Proc. Bath F.C., vol. iii, pp. 300-4. 

WINWOOD, H. H., & RICHARDSON, L., 1910. Notes on a White Lias Section at Saltford 

near Bath. Proc. Cots. N.F.C., vol. xvii, pp. 45-50.


WOODWARD, H. B., 1889. Notes on the Rhaetic Beds and Lias of Glamorganshire. 

P.G.A., vol. x, pp. 529-38. 

, 1892. Remarks on the Formation of Landscape Marble. Geol. Mag. [3], 

vol. ix, pp. 110-14. 

WOODWARD, H. B., & BLAKE, J. H., 1872. Notes on the Relations of the Rhaetic Beds 

to the Lower Lias and Keuper Formations in Somersetshire. Geol. Mag., vol. ix, 

pp.196-202. 

WRIGHT, T., i860. On the Zone of Avicula contorta and the Lower Lias of the South 

of England. Q.J.G.S., vol. xvi, pp. 374-411. 

, 1864. On the W T hite Lias of Dorsetshire. Geol. Mag., vol. i, pp. 290-2; and 

Rept. Brit. Assoc. for 1864, p. 75. 

LOWER LIAS 

BECHE, H. T. DE LA, 1822. Remarks on the Geology of the South Coast of England, 

from Bridport Harbour, Dorset, to Babbacombe Bay, Devon [Lower Lias and 

Keuper]. Trans. Geol. Soc. [2], vol. i, pp. 40-7. 

, 1826. On the Lias of the Coast in the Vicinity of Lyme Regis. Trans. Geol. 

Soc. [2], vol. ii, pp. 21-30. 

BEESLEY, T., 1877. The Lias of Fenny Compton, Warwickshire, Proc. Warwicks. 

N.F.C. for 1877, pp. 1-22; and 8vo, Banbury. 

BLAKE, J. F., 1871. Foraminifera from the Lias of Cliffe, near Market Weighton. 

Proc. Yorks. Nat. Club for 1871, p. 13. 

, 1872. On the Infralias in Yorkshire. Q.J.G.S., vol. xxviii, pp. 132-46. 

, 1887-8. On a Starfish [Solaster] from the Yorkshire Lias. Rept. Brit. Assoc. 

for 1887, p. 716; Nature, vol. xxxvi, p. 591; Geol. Mag. [3], vol. iv, pp. 529-31. 

, 1891. The Geology of the Country between Redcar and Bridlington. P.G.A., 

vol. xii, pp. 115-44- 

BRISTOW, H. W., 1867. On the Lower Lias or Lias-Conglomerate of a part of 

Glamorganshire. Q.J.G.S., vol. xxiii, pp. 199-207. 

BRODIE, P. B., 1857. On Some Species of Corals in the Lias of Gloucestershire, 

Worcestershire, Warwickshire, and Scotland. Edinburgh New Phil. Journ., N.S., 

vol. v, pp. 260-4. 

, i860. Remarks on the Lias of Barrow, in Leicestershire, compared with the 

Lower Part of that formation in Gloucestershire, Worcestershire and Warwickshire. 

Proc. Cots. N.F.C., vol. ii, pp. 139-41. 

, 1861. On the Distribution of Corals in the Lias. Q.J.G.S., vol. xvii, pp. 151-2, 

and Rept. Brit. Assoc. for i860, pp. 73-4. 

, 1864-5. On the Lias Outliers at Knowle and Wootton Wawen in S. Warwickshire, 

and on the Presence of the Lias or Rhaetic Bone Bed at Copt Heath. Q.J.G.S., 

vol. xxi, pp. 159-61; and Rept. Brit. Assoc. for 1864, p. 52. 

, 1866. Notes on a Section of Lower Lias and Rhaetic Beds near Wells, Somerset. 

Q.J.G.S., vol. xxii, pp. 93-5. 

• , 1867. On the Correlation of the Lower Lias at Barrow-on-Soar in 

Leicestershire with the same strata in Warwickshire, Worcestershire and Gloucestershire. 

Ann. Mag. Nat. Hist. [3], vol. xix, pp. 31-4. 

BROWN, T., 1843. Description of some New Species of the Genus Pachyodon [= Cardinia]. 

Ann. Mag. Nat. Hist., N.S., vol. xii, pp. 390-6. 

BUCKLAND, W., 1829. On the Discovery of Coprolites, or Fossil Faeces, in the Lias 

at Lyme Regis, and in other Formations. P.G. Soc., vol. i, pp. 96-8. Trans. Geol. 

Soc. [2], vol. iii, pp. 217-22. 

BUCKMAN, J., 1842. On the Lias Beds near Cheltenham. Geologist (Moxon's), 

pp. 14-20. 

, 1879. On Belemnoteuthis montefiorei [from the Lower Lias between Charmouth 

and Lyme Regis]. Proc. Dorset N.F.C., vol. iii, pp. 141-3. 

BUCKMAN, S. S., 1906. Some Lias Ammonites: Schlotheimia and Species of other 

Genera. Proc. Cots. N.F.C., vol. xv, pp. 231-54. 

, 1907. Some Species of the Genus Cincta. Proc. Cots. N.F.C., vol. xvi, 

pp. 41-63. 

, 1915. A Palaeontological Classification of the Jurassic Rocks of the Whitby

LOWER LIAS 635 

District, with a Zonal Table of Lias Ammonites. In Fox-Strangways and Barrow, 

Geol. Whitby and Scarboro., Mem. Geol. Surv., 1915 (2nd edition). 

BUCKMAN, S. S., 1917-20. Jurassic Chronology; I. Lias. Q.J.G.S., vol. lxxiii,pp. 257- 

327; and Supplement: West of England Strata. Q.J.G.S., vol. lxxvi, pp. 62-103. 

COLE, G. A. J., 1917. Jurassic [Lower Lias]; Ireland. In Handb. Reg. Geol., British 

Isles, pp. 245-6. 

Cox, L. R., 1928. Gastropods and Lamellibranchs from the Belemnite Marls. 

Appendix to paper by W. D. Lang. Q.J.G.S., vol. lxxxiv, pp. 233-45. 

COYSH, A. W., 1931. U-shaped Burrows in the Lower Lias of Somerset and Dorset. 

Geol. Mag., vol. lxviii, pp. 13-15. 

CRICK, G. C., 1920. On Nautilus pseudotruncatus n.sp. from the Liassic Rocks of 

England. Proc. Cots. N.F.C., vol. xx, p. 245. 

CRICK, W. D., & SHERBORN, C. D., 1891-2. On Some Liassic Foraminifera from 

Northamptonshire. Journ. Northants. N.H.S., vol. vi, pp. 208-14, and vol. vii, 

PP-67-73. 

DAY, E. C. H., 1865. On the Lower Lias of Lyme Regis. Geol. Mag., vol. ii, pp.518-19. 

DUNCAN, P. M., 1867. On the Madreporaria of the Infra-Lias of South Wales 

[chiefly from the Sutton and Southerndow r n Series], Q.J.G.S., vol. xxiii, pp. 12-28. 

, 1886. On the Structure and Classificatory Position of some Madreporaria from 

the Secondary Strata of England and South Wales. Q.J.G.S., vol. xlii, pp. 113-42. 

, 1886. On the Astrocoeniae of the Sutton Stone and other Deposits of the 

Infra-Lias of South Wales. Q.J.G.S., vol. xlii, pp. 101-12. 

ETHERIDGE, R., 1864. Description of New Species of Mollusca, &c. [from the Lower 

Lias near Belfast, Ireland]. Q.J.G.S., vol. xx, pp. 112-14. 

GAVEY, G. E., 1853. On the Railway Cuttings [in Lower Lias] at the Mickleton 

Tunnel and at Aston Magna, Gloucestershire. Q.J.G.S., vol. ix, pp. 29-37. 

GROOM-NAPIER, C. O., 1868. On the Lower Lias Beds occurring at Cotham, Bedminster 

and Keynsham, near Bristol. Q.J.G.S., vol. xxiv, pp. 204-5. 

HOLMES, T. V., 1881. The Permian, Triassic and Liassic Rocks of the Carlisle Basin. 

Q.J.G.S., vol. xxxvii, pp. 286-98. 

JONES, J., & TOMES, R. F., 1865. The Sutton Beds of Glamorganshire. Proc. Cots. 

N.F.C., vol. iii, p. 191. 

JUKES-BROWNE, A. J., 1908. The Burning Cliff and the Landslip at Lyme Regis. 

Proc. Dorset N.F.C., vol. xxix, pp. 153-60. 

LANG, W. D., 1913. The Lower Pliensbachian—'Carixian*—of Charmouth. Geol. 

Mag. [v], vol. x, pp. 401-12. 

, 1914. The Geology of the Charmouth Cliffs, Beach and Foreshore. P.G.A., 

vol. xxv, pp. 293-360. 

, 1917. The Ibex-Zone at Charmouth, and its Relation to the Zones near it. 

P.G.A., vol. xxviii, pp. 30-6. 

LANG, W. D., SPATH, L. F., & RICHARDSON, W. A., 1923. Shales-with-'Beef: a 

Sequence in the Low r er Lias of the Dorset Coast. Q.J.G.S., vol. Ixxix, pp. 47-99. 

LANG, W. D., 1924. The Blue Lias of the Devon and Dorset Coasts. P.G.A., vol. 

xxxv, pp. 169-85. 

LANG, W. D., SPATH, L. F., COX, L. R., & MUIR-WOOD, H. M., 1926. The Black 

Marl of Black Ven and Stonebarrow in the Lias of the Dorset Coast. Q.J.G.S., vol. 

lxxxii, pp. 144-87. 

, 1928. The Belemnite Marls of Charmouth, a Series in the Lias of the 

Dorset Coast. Q.J.G.S., vol. lxxxiv, pp. 179-257. 

LANG, W. D., 1932. The Lower Lias of Charmouth and the Vale of Marshwood. 

P.G.A., vol. xliii, pp. 97-126. 

LUCAS, S., 1862. Section of the Lias Clay in a railway-cutting near Stow on the 

Wold. Geologist, vol. v, pp. 127-8. 

LUCY, W. C., 1886. On the Southerndown, Dunravcn, and Bridgend Beds. Proc. 

Cots. N.F.C., vol. viii, pp. 254-64. 

LYCETT, J., 1863. On Gryphcea incurva and its varieties. Proc. Cots. N.F.C., vol. iii, 

pp. 81-96; and Correspondence as to Geological Position, by J. Jones and R. F. 

Tomes, ibid., pp. 191-4. 

LYDEKKER, R., 1891. Note on a nearly perfect Skeleton of Ichthyosaurus tenuirostris 

from the Lower Lias of Street, Somerset. Geol. Mag. [3], vol. viii, pp. 289-90.


MCDONALD, A. I., & TRUEMAN, A. E., 1921. The Evolution of Certain Liassic 

Gastropods, with Special Reference to their Use in Stratigraphy. Q.J.G.S., vol. 

lxxvii, pp. 297-344. 

MOORE, C., 1867. On Abnormal Conditions of Secondary Deposits when connectcd 

with the Somersetshire and South Wales Coal-basins, and on the Age of the Sutton 

and Southerndown Series. Q.J.G.S., vol. xxiii, pp. 449-568. 

, 1877. The Liassic and other Secondary Deposits of the Southerndown Series. 

Trans. Cardiff Nat. Soc., vol. viii, pp. 53-60. 

MORTON, G. H., 1864. On the Lias Formation as developed in Shropshire. Proc. 

Liverpool Geol. Soc., Session 5, pp. 2-6. 

PARIS, E. T., 1908. Notes on some Echinoids from the Lias of Worcestershire, 

Gloucestershire and Somerset. Proc. Cots. N.F.C., vol. xvi, pp. 143-50. 

PORTLOCK, J. E., 1843. Report on the Geology of the County of Londonderry and of 

parts of Tyrone and Fermanagh [Lower Lias]. Dublin. 

QUILTER, H. E., 1881. Exposure of the Middle Series of the Bucklandi Beds in 

Leicestershire. Mid. Nat., vol. iv, p. 265. 

, 1886. The Lower Lias of Leicestershire. Geol. Mag. [3], vol. iii, pp. 59-65. 

READE, T. M., 1876. The Lower Lias of Street, Somerset. Proc. Liverpool Geol. 

Soc., vol. iii, pp. 97-9. 

RICHARDSON, L., 1905. The Lias of Worcestershire [almost entirely Lower Lias]. 

Trans. Worcestershire Nat. C., vol. iii, part iv, pp. 188-209. 

, 1906. On a Section of Lower Lias at Maisemore, near Gloucester. Proc. Cots. 

N.F.C., vol. xv, pp. 259-62. 

, 1906. Liassic Dentaliidae. Q.J.G.S., vol. lxii, p. 573. 

, 1908. On a Section of Lower Lias at Hock Cliff, Fretherne, Gloucestershire. 

Proc. Cots. N.F.C., vol. xvi, pp. 135-42. 

, 1918. The Geology [Lias and Superficial Deposits] of the Cheltenham-Stratford 

on Avon Railway (G.W.R.). Trans. Woolhope N.F.C. for 1916 (1918), pp. 137-53. 

, 1926. A Deep Boring at Rooksbridge, East Brent, Somerset [Alluvium and 

Lower Lias]. Proc. Somerset Arch. N.H. Soc. [4], vol. lxxii, pp. 73-5. 

RICHARDSON, L., WALTERS, R. C. S., & TRUEMAN, A. E., 1922. Lower Lias Section 

at Hayden, near Cheltenham, with notes on the Ammonites. Proc. Cots. N.F.C., 

vol. xxi, pp. 167-76. 

SEELEY, H. G., 1870. On Zoocapsia dolichorhamphia, a Sessile Cirripede from the Lias 

of Lyme Regis. Ann. Mag. Nat. Hist. [4], vol. v, p. 283. 

SIMPSON, M., 1855. The Fossils of the Yorkshire Lias. Whitby; 2nd edition, 1884. 

SOLLAS, W. J., 1881. On a Species of Plesiosaurus (P. conybeari) from the Lower Lias 

of Charmouth; with Observations on P. megacephalus Stutchbury and P. brachycephalus 

Owen. Q.J.G.S., vol. xxxvii, pp. 440-80. 

, 1882. On a Rare Plesiosaur from the Lias at Bridport. Proc. Bristol Nat. Soc. 

[2], vol. iii, pp. 322-3. 

SPATH, L. F., 1914. The Development of Tragophylloceras loscombi [Lower Lias]. 

Q.J.G.S., vol. lxx, pp. 336-62. 

, 1922. On Lower Lias Ammonites from Skye. Geol. Mag., vol. lix, pp. 170-6. 

, 1922. On the [Lower] Liassic Succession of Pabay, Inner Hebrides. Geol. Mag., 

vol. lix, pp. 548-51. 

, 1923. Correlation of the Ibex and Jamesoni Zones of the Lower Lias. Geol. 

Mag., vol. lx, pp. 6-11. 

, 1924. The Ammonites of the Blue Lias. P.G.A., vol. xxxv, pp. 186-211. 

, 1925. Notes on Yorkshire Ammonites: 

I. On the genus Oxynoticeras Hyatt, Naturalist, 1925, pp. 107-12. 

II. On a Deroceratid, ibid., 1925, pp. 137-41. 

III. On the 4 Armatus Zone', ibid., 1925, pp. 167-72. 

IV. On Some Schlotheimidae, ibid., 1925, pp. 201-6. 

V. Arietitesy Asteroceras, and allied Genera, ibid., 1925, pp. 263-9. 

VI. On Ammonites planicosta J. Sow., ibid., 1925, pp. 299-306. 

VII. On Ammonites semicostatus Y. & Bird, ibid., 1925, pp. 327-31. 

VIII. More Lower Liassic Forms, ibid., 1925, pp. 359-64; 1926, pp. 45-9, 137-40, 

169-71. 

IX. On Recent Criticisms, ibid., 1926, pp. 265-8.

LOWER LIAS 637 

SPATH, L. F., 1929. Corrections of Cephalopod Nomenclature [includes Deroceras, 

Microceras, Palceoechioceras (Protechioceras), &c.] Naturalist, 1929, pp. 269-71. 

STODDART, W. W., 1868. Notes on the Lower Lias-Beds of Bristol. Q.J.G.S., 

vol. xxiv, pp. 199-204. 

STRICKLAND, H. E., 1842-4. On the Genus Cardinia Agassiz, as characteristic of the 

Lias Formation. Rept. Brit. Assoc. for 1841, pp. 65-6, and Ann. Mag. Nat. Hist., 

vol. xiv, 1844, pp. 100-8. 

STUTCHBURY, S., 1839. Description of a new fossil [Oxytoma longicostata] from the 

[Lower] Lias Shale of [Saltford], Somersetshire. Ann. Mag. Nat. Hist. [2], vol. iii, 

pp. 163-4. 

STUTCHBURY, S., 1842. On a New Genus of Fossil Bivalve Shells [Pachyodon Stutchbury 

-- Cardinia Agass.] Ann. Mag. Nat. Hist., N.S., vol. viii, pp. 481-5. 

SWINTON, W. E., 1930. Preliminary Account of a New Genus and Species of Plesiosaur 

[Macropterus tenuiceps, Low r er Lias, Harbury]. Ann. Mag. Nat. Hist. [10], 

vol. vi, pp. 206-9. 

TATE, R., 1864. On the [Rhaetic and] Liassic Strata of the Neighbourhood of Belfast. 

Q.J.G.S., vol. xx, pp. 103-11. 

, 1867. On the Lower Lias of the North-East of Ireland. Q.J.G.S., vol. xxiii, 

pp.297-305. . . . 

, 1867. On the Fossiliferous development of the zone of Ammonites angulatus 

Schloth. in Great Britain. Q.J.G.S., vol. xxiii, pp. 305-14. 

, 1871. A Census of the Marine Invertebrate Fauna of the Lias. Geol. Mag., 

vol. viii, pp. 4-11. 

, 1875. On the Lias about Radstock. Q.J.G.S., vol. xxxi, pp. 493-510. 

TATE, R., & BLAKE, J. F., 1876. The Yorkshire Lias. London. 

THOMPSON, B., 1899. The Geology [Lower Lias and Superficial] of the Great Central 

Railway: Rugby to Catesby. Q.J.G.S., vol. Iv, pp. 65-88. 

THOMPSON, C., 1925. An Addition to the Ammonites of the Yorkshire [Lower] Lias 

[Wcehnoceras sp.], Naturalist, 1925, pp. 43-4. 

THORNTON, W., 1881. The Liassic Strata in the Western Highlands of Scotland. 

Journ. Northants. N.H.S., vol. i, pp. 170-8. 

TOMES, R. F., 1888. On Heterastrceay a New Genus of Madreporaria from the Lower 

Lias. Geol. Mag. [3], vol. v, pp. 207-18. 

, 1893. Description of a new Genus of Madreporaria from the Sutton Stone of 

South Wales. Q.J.G.S., vol. xlix, pp. 574-8. 

, 1878. On the Stratigraphical Position of the Corals of the Lias of the Midland 

and Western Counties of England and of South Wales. Q.J.G.S., vol. xxxiv, 

pp.179-95. 

TRUEMAN, A. E., 1915. The Fauna of the Hydraulic Limestones in South Notts. 

Geol. Mag. [6], vol. ii, pp. 150-2. 

, 1918. The [Lower] Lias of South Lincolnshire. Geol. Mag. [6], vol. v, 

PP- 64-73, 101-3. 

, 1918. The Evolution of the Liparoceratidae. Q.J.G.S., vol. lxxiv, pp. 247-98. 

, 1920. The Liassic Rocks of the Cardiff District. P.G.A., vol. xxxi, pp. 93-107. 

, 1922. The Liassic Rocks of Glamorgan. P.G.A., vol. xxxiii, pp. 245-84. 

, 1922. The Use of Gryphcea in the Correlation of the Lower Lias. Geol. Mag., 

vol. lix, pp. 256-68. 

, 1930. The Lower Lias (Bucklandi Zone) of Nash Point, Glamorgan. P.G.A., 

vol. xii, pp. 148-59. 

, 1930. Records of some Ammonites from the Lower Lias of Gloucestershire 

and Worcestershire. Proc. Cots. N.F.C., vol. xxiii, pp. 245-51. 

TRUEMAN, A. E., & WILLIAMS, D. M., 1925. Studies in the Ammonites of the Family 

Echioceratidae. Trans. Roy. Soc. Edinburgh, vol. liii, pp. 699-739. 

, 1927. Notes on some [Lower] Lias Ammonites from the Cheltenham District 

[Cheltenham-Honeybourne Railway]. Proc. Cots. N.F.C., vol. xxii, pp. 239-53; 

also in Geol. Moreton in Marsh, by L. Richardson, Mem, Geol. Surv., 1929. 

TUTCHER, J. W., 1917. The Zonal Sequence of the Lower Lias (Lower Part). Q.J.G.S., 

vol. lxxiii, pp. 278-81. 

TUTCHER, J. W., & TRUEMAN, A. E., 1925. The Liassic Rocks of the Radstock 

District, Somerset. Q.J.G.S., vol. lxxxi, pp. 595-666.


UPTON, C., 1913. On the abundant occurrence of Involutina liassica (Jones) in the 

Lower Lias at Gloucester. Proc. Cots. N.F.C., vol. xviii, p. 72. 

VAUGHAN, A., 1903. The Lowest Beds of the Lower Lias at Sedbury Cliff. Q.J.G.S., 

vol. lix, pp. 396-402. 

VAUGHAN, A., & TUTCHER, J. W., 1903. The Lias of the Neighbourhood of Keynsham. 

Proc. Bristol Nat. Soc., N.S., vol. x, p. 22. 

VEITCH, W., 1886. Three new Species observed in the Yorkshire Lias. [Chonetes 

clevelandicus Veitch, Pleuromya navicula Veitch and the coral Isis liasica Veitch.] 

Proc. Yorks. Geol. Soc., vol. ix, p. 54. 

WEDD, C. B., 1920. Frodingham [Iron Ore] (Lower Lias); in Lamplugh, Wedd and 

Pringle, Spec. Repts. Min. Resources Gt. Brit., vol. xii—Bedded Ores, ch. iv, 

pp. 71-105. Mem. Geol. Survey. 

WHIDBORNE, G. F., 1881. On a new Species of Plesiosaurus (P. Conybeari) from the 

Lower Lias of Charmouth, with observations on other species. Q.J.G.S., 


WILSON, E., 1887. British Liassic Gasteropoda. Geol. Mag. [3], vol. iv, pp. 193-202, 

258-62. 

WITHERS, T. H., 1920. The Cirrepede Subgenus Scillcelepas; its Probable Occurrence 

in the Jurassic [Lower Lias] Rocks (S. gaveyi sp. n.). Ann. Mag. Nat. Hist. [9], 

vol. v, pp. 258-64. 

WOODWARD, A. S., 1890. Notes on some Ganoid Fishes from the English Lower Lias. 

Ann. Mag. Nat. Hist. [6], vol. v, pp. 430-6. 

, 1895. On the Liassic Fish Osteorachis macrocephalus. Geol. Mag. [4], vol. ii, 

pp. 204-6. 

WOODWARD, H., 1866. On a new Crustacean (Aeger marderi) from the Lias of Lyme 

Regis, Dorset. Geol. Mag., vol. iii, pp. 10-13. 

, 1888. On a New Species of Aeger from the Lower Lias of Wilmcote, Warwickshire. 

Geol. Mag. [3], vol. v, pp. 385-7. 

, 1888. On Eryon antiquus Broderip sp., from the Lower Lias of Lyme Regis, 

Dorset. Geol. Mag. [3], vol. v, pp. 433-41. 

, 1892. On a Neuropterous Insect from the Lower Lias, Barrow-on-Soar, 

Leicestershire. Geol. Mag. [3], vol. ix, pp. 193-8. 

WOODWARD, H. B., 1905. Notes on the Railway-cuttings [in Lower Lias and some 

Rhaetic Beds] between Castle Cary and Langport, in Somerset. Sum. Prog. Geol. 

Surv. for 1904, pp. 163-9. 

MIDDLE AND UPPER LIAS 

BATHER, F. A., 1886. Notes on some Recent Openings in the Liassic and Oolitic Rocks 

of Fawler in Oxfordshire, and the Arrangement of those Rocks near Charlbury. 

Q.J.G.S., vol. xlii, pp. 143-6. 

BEESLEY, T., 1872. A Sketch of the Geology of the Neighbourhood of Banbury. 

Proc. Warwicks. N.F.C., 1872, pp. n-34, and Geol. Mag., vol. ix, pp. 279-82. 

BLAKE, J. F., 1887. On a new Specimen of Solaster murchisoni from the Yorkshire 

Lias. Geol. Mag. [3], vol. iv, p. 529. 

BOSWELL, P. G. H., 1924. The Petrography of the Sands of the Upper Lias and Lower 

Inferior Oolite in the West of England. Geol. Mag., vol. lxi, pp. 246-64. 

BRADY, H. B., 1865. On the Foraminifera of the Middle and Upper Lias of Somersetshire. 

Rept. Brit. Assoc. for 1864, p. 50. 

BRODIE, P. B., 1843. Notice on the Discovery of the Remains of Insects in the Lias 

of Gloucestershire. Proc. Geol. Soc., vol. iv, pp. 14-16, and Rept. Brit. Assoc. for 

1842, p. 58. • , • 

, 1849. Notice on the Discovery of a Dragon-fly and a new Species of Leptolepis 

in the Upper Lias near Cheltenham, with a few remarks on that Formation in 

Gloucestershire. Q.J.G.S., vol. v, pp. 31-7. 

, i860. Remarks on the Inferior Oolite and Lias in parts of Northamptonshire 

compared with the same formations in Gloucestershire. Proc. Cots. N.F.C., 

vol. ii, pp. 132-4. 

BUCKMAN, J., 1843. On the Occurrence of the Remains of Insects in the Upper Lias 

of the County of Gloucester. Proc. Geol. Soc., vol. iv, pp. 211-12.

MIDDLE AND UPPER LIAS 639 

BUCKMAN, J., 1853. Remarks on Libellula Brodiei (Buckman), a Fossil Insect from the 

Upper Lias of Dumbleton. Proc. Cots. N.F.C., vol. i, pp. 268-70. 

, 1875. On the Cephalopoda-Bed and the Oolite Sands of Dorset and Part of 

Somerset. Proc. Somerset Arch. Soc., vol. xx, pp. 140-64. 

, 1877. The Cephalopoda-Bed of Gloucester, Dorset and Somerset. Q.J.G.S., 

vol. xxxiii, pp. 1-9. 

, 1879. On the so-called Midford Sands. Q.J.G.S., vol. xxxv, pp. 736-43. 

BUCKMAN, S. S., 1887. On Anunonites serpentinus, Am.falcifer, Am. elegans> &c. Geol. 

Mag. [3], vol. iv, pp. 396-400. 

, 1889. On the Cotteswold, Midford, and Yeovil Sands, and the Division between 

the Lias and Oolite. Q.J.G.S., vol. xlv, pp. 440-73. 

, 1890. On the so-called 'Upper Lias' Clay of Down Cliffs. Q.J.G.S., vol. xlvi, 

pp. 518-21. 

, 1890. On the Jurense-Zone. Journ. Northants. N.H.S., vol. vi, pp. 76-80. 

, 1892. The Reported Occurrence of Ammonites jurensis in the Northampton 

Sands. Geol. Mag. [3], vol. ix, pp. 258-60. 

, 1903. TheToarcian of BredonHill, and a Comparison with Deposits elsewhere. 

Q.J.G.S., vol. lix, pp. 445-64. 

, 1905. On Certain Genera and Species of Lytoceratidce. Q.J.G.S., vol. Ixi, 

pp.142-54. 

, 1910. Certain Jurassic (Lias-Oolite) Strata of South Dorset; and their Correlation. 

Q.J.G.S., vol. lxvi (Upper Lias), pp. 80-9. 

, 1911. Comparison of the Upper Toarcian Beds in Yorkshire and the Cotteswold 

Hills. Appendix to paper by L. Richardson. Proc. Yorks. Geol. Soc., N.S., 

vol. xvii, pp. 209-12. 

, 1922. Jurassic Chronology; II. Preliminary Studies. Certain Jurassic Strata 

near Eypesmouth (Dorset); the Junction Bed of Watton Cliff and Associated Rocks. 

Q.J.G.S., vol. lxxviii, pp. 378-475- 

BURTON, J. J., 1913. The Cleveland Ironstone. Naturalist, 1913, pp. 161-8, 185-94. 

CARR, W. D., 1883. The Lincoln Lias [Middle and Upper]. Geol. Mag. [2], vol. x, 

pp.164-9. 

COOKE, J. H., 1897. On a New Section in the Middle Lias of Lincoln. Geol. Mag. 

[4], vol. iv, pp. 253-9. 

CRICK, G. C., 1920. On some Dibranchiate Cephalopoda from the Upper Lias of 

Gloucestershire. Proc. Cots. N.F.C., vol. xx, pp. 249-56. 

DAY, E. C. H., 1863. On the Middle and Upper Lias of the Dorsetshire Coast. 

Q.J.G.S., vol. xix, pp. 278-97. 

DUNN, J., 1831. On a Large Species of Plesiosaurus in the Scarborough Museum [from 

the Upper Lias near Whitby]. P.G.A., vol. i, pp. 336-7. 

GORHAM, A., 1930. The Upper and Lower Junctions of the Midford Sands at Limpley 

Stoke, south-east of Bath. Geol. Mag., vol. lxvii, pp. 289-97. 

HAWELL, J., 1897. Description of two New Species of Gasteropoda from the Upper 

Lias of Yorkshire. Proc. Yorks. Geol. Soc., vol. xiii, pp. 199, 200. 

HINDE, G. J., 1889. On a true Leuconid Calcisponge from the Middle Lias of 

Northamptonshire. Ann. Mag. Nat. Hist. [6], vol. iv, pp. 352-7. 

HULL, E., 1860-1. On the Blenheim Iron-ore and the thickness of the formations 

below the Great Oolite at Stonesfield. Geologist, vol. iii, pp. 303-5, and Rept. 

Brit. Assoc. for i860, pp. 81-3. 

HUNTON, L., 1836. Remarks on a Section of the Upper Lias and Marlstone of Yorkshire, 

showing the limited vertical range of the Species of Ammonites and other 

Testacea, with their value as Geological Tests. Trans. Geol. Soc. [2], vol. v, 

pp.215-21. 

JACKSON, J. F., 1922. Sections of the Junction-Bed and Contiguous Deposits. Appendix 

to Jurassic Chronology, II, by S. S. Buckman. Q.J.G.S., vol. lxxviii, pp. 

436-48. 

, 1926. The Junction-Bed of the Middle and Upper Lias on the Dorset Coast. 

Q.J.G.S., vol. lxxxii, pp. 490-525. 

LAMPLUGH, G. W., 1920. Cleveland District (Lias and Oolite) [Iron Ores]; in Lamplugh, 

Wedd, and Pringle. Spec. Repts. Min. Resources Gt. Brit., vol. xii—Bedded 

Ores, chs. i and ii, pp. 1-64. Mem. Geol. Surv.


LYCETT, J., 1862. On some Sections of the Upper Lias recently exposed at Nailsworth, 

Gloucestershire. Proc. Cots. N.F.C., vol. ii, pp. 155-63. 

, 1862. On the Sands intermediate the Inferior Oolite and Lias of the Cotteswold 

Hills compared with a similar Deposit upon the Coast of Yorkshire. Proc. Cots. 

N.F.C., vol. ii, pp. 142-9; and Notes on the Ammonites of the Sands. Vol. iii, 

pp. 3-10. 

MACMILLAN, W. E. F., 1925-31. Yeovilian Ammonites in the Inland Area of the 

Yorkshire Moors. Naturalist, 1925, pp. 236, 316; 1926, pp. 51-3; and 1931, p. 345. 

MELMORE, S., 1931. A Reptilian Egg from the [PUpper] Lias of Whitby. Proc. 

Yorks. Phil. Soc. for 1930, pp. 1-3. 

MOORE, C., 1853. On the Palaeontology of the Middle and Upper Lias. Proc. Somerset 

Arch. Soc., vol. iii, pp. 61-76. 

, 1867. On the Middle and Upper Lias of the South-West of England. Proc. 

Somerset Arch. Soc., vol. xiii, pp. 119-244. 

NEWTON, E. T., 1888. On the Skull, Brain and Auditory Organ of a new Species of 

Pterosaurian (Scaphognathus purdoni) from the Upper Lias near Whitby. Proc. Roy. 

Soc., vol. xliii, pp. 436-40; Phil. Trans. Roy. Soc., vol. clxxix B, pp. 503-37. 

PARKIN, C., 1882. On Jet Mining. Trans. N. Eng. Inst. Mining Eng., vol. xxxi, 

pp. 51-8. 

PRESTON, H., 1903. On a new Boring at Caythorpe, Lincolnshire [mainly in Middle 

and Upper Lias]. Q.J.G.S., vol. lix, pp. 29-32. 

PRESTON, H., & TRUEMAN, A. E., 1917. Oolite Grains in the Upper Lias of Grantham. 

Naturalist, 1917, p. 217. 

RASTALL, R. H., 1905. The Blea Wyke Beds and the Dogger in North-East Yorkshire. 

Q.J.G.S., vol. lxi, pp. 441-60. 

RICHARDSON, L., 1902. Notes on the Geology of Bredon Hill. Trans. Woolhope 

N.F.C. for 1902, p. 65. 

, 1906. On a Section of Middle and Upper Lias Rocks near Evercreech, Somerset. 

Geol. Mag. [5], vol. iii, pp. 368-9. 

, 1906. On a Well-Sinking in the Upper Lias at Painswick, near Stroud. Proc. 

Cots. N.F.C., vol. xv, p. 208. 

, 1909. On some Middle and Upper Lias Sections near Batcombe, Somerset, 

Geol. Mag. [5], vol. vi, pp. 540-2. 

, 1921. Ammonites from the Upper Lias, Railway-cutting, Bloxham, Oxon. 

Geol. Mag., vol. lviii, pp. 426-8. 

SCHINDEWOLF, O. H., 1928-31. T)ber Farbstreifen bei Amaltheus {Paltopleuroceras) 

spinatus (Brug.). Pal. Zeitschr., vol. x, pp. 136-43; and vol. xiii, pp. 284-7. 

SEELEY, H. G., 1865. On Plesiosaurus macropterus, a New Species from the Lias of 

Whitby. Ann. Mag. Nat. Hist. [3], vol. xv, pp. 49-53, 232. 

, 1880. Notes on the Skulls of a large Teleosaurus and an Ichthyosaurus from the 

Whitby Lias, preserved in the Museum of the University of Cambridge. Q.J.G.S., 


SEWARD, A. C., 1902. The Structure and Origin of Jet. Rept. Brit. Assoc. for 1901, 

Glasgow, p. 856. 

SMITHE, F., 1865. Geology of Churchdown Hill. Proc. Cots. N.r.C., vol. iii, 

pp. 40-9. 

, 1877. On the Middle Lias of North Gloucestershire. The Spinatus Zone. And 

on the Occurrence of Plicatula Icevigata d'Orb. in the Middle Lias. Proc. Cots. 

N.F.C., vol. vi, pp. 341-404. 

, 1895. On the [Middle and Upper] Liassic Zones and Structure of Churchdown 

Hill, Gloucester. Proc. Cots. N.F.C., vol. xi, pp. 247-56. 

SMITHE, F., & LUCY, W. C., 1892. Some Remarks on the [Middle and Upper] Lias 

of Alderton, Gretton and Ashton-under-Hill. Proc. Cots. N.F.C., vol. x, pp. 202-12. 

SORBY, H. C., 1857. On the Origin of the Cleveland Hill Ironstone. Proc. Yorks. 

Geol. Soc., vol. iii, pp. 457-61. 

SPATH, L. F., PRINGLE, J., TEMPLEMAN, A., & BUCKMAN, S. S., 1922. The Upper 

Lias Succession near Ilminster, Somerset, and Correlation. In Buckman, Q.J.G.S., 

vol. lxxviii, pp. 449-55. 

STRICKLAND, H. E., 1840. On the Occurrence of a Fossil Dragon-fly, from the Lias 

of Warwickshire \JEschna liassina], Ann. Mag. Nat. Hist. [2], vol. iv, pp. 301-3.

MIDDLE AND UPPER LIAS 641 

TATE, R., 1870. Note on the Middle Lias [fossils from the Drift] in the North-East 

of Ireland. Q.J.G.S., vol. xxvi, pp. 324-5. 

, 1870. On the Palaeontology of the Junction Beds of the Lower and Middle Lias 

in Gloucestershire. Q.J.G.S., vol. xxvi, pp. 394-408. 

, 1875. On some New Liassic Fossils [Ammonites acutus and gastropods from 

Middle Lias]. Geol. Mag. [2], vol. ii, pp. 203-6. 

TATE, R., BLAKE, J. F., & LECKENBY, J., 1872-3. Notes on the Discovery of the oldest 

know r n Trigonia (T. lingonensis Dum.) in Britain [Spinatum zone, Yorks.]. Geol. 

Mag., vol. ix, p. 306, and vol. x, pp. 135, 186. 

THOMPSON, B., 1889. The Middle Lias of Northamptonshire, considered 1, stratigraphically; 

2, palaeontologically; 3, economically; 4, as a source of water-supply; 

5, as a mitigator of floods. (Reprinted from the 'Midland Naturalist'.) London. 

, 1892. Report of the Committee to work the very Fossiliferous Transition Bed 

between the Middle and Upper Lias in Northamptonshire. Rept. Brit. Assoc. for 

1891, pp. 334-51. 

THOMPSON, C., 1909. The Ammonites called A. serpentinus [with descriptions and 

figures of allied forms]. Naturalist, 1909, pp. 214-19. 

THORNEYCROFT, W., I914. Note on the Upper Lias of the Western Islands in Reference 

to the Iron-ore Deposit therein. Trans. Geol. Soc. Edin., vol. x, p. 196. 

TOMES, R. F., 1882. Description of a New Species of Coral from the Middle Lias of 

Oxfordshire. Q.J.G.S., vol. xxxviii, pp. 95-6. 

, 1886. On the Occurrence of Two Species of Madreporaria in the Upper Lias 

of Gloucestershire. Geol. Mag. [3], vol. iii, pp. 107-11. 

TRUEMAN, A. E., 1918. The [Middle and Upper] Lias of South Lincolnshire. Geol. 

Mag. [6], vol. v, pp. 103-11. 

UPTON, C., 1906. On a Section of Upper Lias at Stroud. Proc. Cots. N.F.C., 

vol. xv, pp. 201-7. 

WALFORD, E. A., 1879. On some Upper and Middle Lias Beds in the Neighbourhood 

of Banbury. Proc. Warwicks. N.F.C., Supplt. for 1878, pp. 1-23. 

, 1887. Notes on some Polyzoa from the [Middle] Lias. Q.J.G.S., vol. xliii, 

pp.632-6. 

, 1894. On Cheilostomatous Bryozoa from the Middle Lias. Q.J.G.S., vol. 1, 

pp. 79-84. 

, 1889. The Lias Ironstone of North Oxfordshire. Banbury. 

, 1902. On some Gaps in the Lias. Q.J.G.S., vol. lviii, pp. 267-78. 

WALKER, J. F., 1892. On Liassic Sections near Bridport, Dorsetshire. Geol. Mag. [3], 

vol. ix, pp. 437-43- 

WATSON, D. M. S., 1909. A Preliminary Note on two new Genera of Upper Liassic 

Plesiosaurs [Microcleidus and Sthenarosaurusy from Whitby], Mem. Manchester 

Lit. Phil. Soc., vol. liv, no. 4, pp. 1-28. 

, 1910. Upper Liassic Reptilia: the Sauropterygia of the Whitby Museum. Mem. 

Manch. Lit. Phil. Soc., vol. liv, no. 11, pp. 1-13. 

WEDD, C. B., & PRINGLE, J., 1920. Marlstone (Middle Lias) Ores of Lincolnshire, 

Leicestershire, Northamptonshire, Oxfordshire and Warwickshire; in Spec. Repts. 

Min. Resources Gt. Brit., vol.xii—Bedded Ores, ch. v, pp. 106-40. Mem. Geol. Surv. 

WILSON, E., & CRICK, W. D., 1889. The Lias Marlstone of Tilton, Leicestershire, 

with Palaeontological Notes. Geol. Mag. [3], vol. vi, pp. 296-305 and pp. 337-42. 

WITCHELL, E., 1865. On some Sections of the Lias and Sands exposed in the Sewerage 

Works at Stroud. Proc. Cots. N.F.C., vol. iii, pp. 11-14. 

WOODWARD, A. S., 1891. Pholidophorus germanicus: An Addition to the Fish Fauna of 

the Upper Lias of Whitby. Geol. Mag. [3], vol. viii, pp. 545-6. 

, 1896-9. On the Fossil Fishes of the Upper Lias of Whitby. Proc. Yorks. Geol 

Soc., part 1, vol. xiii, pp. 25-42, 155-70/325-37, 455~72- 

, 1911. Euthynotus: a Fossil Fish from the Upper Lias of Dumbleton, Glos. 

Proc. Cheltenham Nat. Sci. Soc., N.S., vol. i, part v, pp. 322-3. 

, 1911. On a New Species of Eryon from the Upper Lias, Dumbleton Hill. 

Geol. Mag. [5], vol. viii, pp. 307-11. 

, 1929. Note on a Specimen of the Ganoid Fish, Lepidotus elvensis (Blainville), 

from the Upper Lias near Ilminster. Proc. Somerset Arch. Soc. [4], vol. xv, 

pp. 91-3, and plate.


WOODWARD, H., 1878. On Penceus Sharpii, a Macrurous Decapod Crustacean, from 

the Upper Lias, Kingsthorpe, near Northampton. Geol. Mag. [2], vol. v, pp. 164-5. 

WOODWARD, H. B., 1872-88. Notes on the Midford Sands. Geol. Mag., vol. ix, 1872, 

pp. 5i3~i5; and [3], vol. v, 1888, pp. 650-1. 

, 1887. Notes on the Geology of Brent Knoll, Somerset. Proc. Bath Nat. Hist. 

Club, vol. vi, pp. 125-30. 

, 1887. Notes on the Ham Hill Stone. Ibid., pp. 182-4. 

, 1893. On a Bed of Oolitic Iron-ore in the Lias of Raasay. Geol. Mag. [3], 

vol. x, p. 493. 

, 1914. Notes on the Geology of Raasay. Trans. Geol. Soc. Edin., vol. x, part 2, 

p. 164. 

WRIGHT, T., 1856. The Palaeontological and Stratigraphical Relations of the so-called 

'Sands of the Inferior Oolite'. Q.J.G.S., vol. xii, pp. 292-325. 

INFERIOR OOLITE SERIES 

BARROW, G., 1877. On a new Marine Bed [Eller Beck Bed] in the Lower Oolites of 

East Yorkshire. Geol. Mag. [2], vol. iv, pp. 552-5. 

BATHER, F. A., & STATHER, J. W., 1925. U-shaped Burrows [of Arenicolites] on [Lower] 

Estuarine Sandstone near Blea Wyke. Proc. Yorks. Geol. Soc., vol. xx, pp. 182-99. 

BRODIE, P. B., 1851. The Basement Beds of the Inferior Oolite in Gloucestershire. 

Q.J.G.S., vol. vii, pp. 208-12. 

BRODIE, P. B., & STRICKLAND, H. E., 1850. On Certain Beds in the Inferior Oolite 

near Cheltenham (Brodie) with notes on a section at Leckhampton Hill (Strickland). 

Q.J.G.S., vol. vi, pp. 239-51. 

BRODRICK, H., 1909. Notes on Footprint Casts from the Inferior Oolite near Whitby, 

Yorkshire. Proc. Liverpool Geol. Soc., vol. x, pp. 327-35; and Rept. Brit. Assoc. 

for 1908 (Dublin), pp. 707-8. 

BUCKMAN, J., 1877. On the Fossil Beds of Bradford Abbas and its Vicinity. Proc. 

Dorset N.F.C., vol. i, pp. 64-72. 

, 1879. On a Series of Sinistral Gastropods [Cirrus spp. from the Inferior Oolite]. 

Proc. Dorset N.F.C., vol. iii, pp. 135-40. 

, 1880. On the New Genus of Bivalve, Curvirostrum striatum [= Isoarca, from 

the Sowerbyi zone of the Inferior Oolite, Halfway House, near Yeovil]. Proc. Dorset 

N.F.C., vol. iv, pp. 102-3. 

, 1881. On the Trigonia bella from [the Inferior Oolite of] Eype, near Bridport, 

Dorset. Proc. Dorset N.F.C., vol. v, pp. 154-6, and plate. 

BUCKMAN, S. S., 1878. On the Species of Astarte from the Inferior Oolite of the 

Sherborne District. Proc. Dorset N.F.C., vol. ii, pp. 81-92. 

, 1880. Some New Species of Ammonites from the Inferior Oolite. Proc. Dorset 

N.F.C., vol. iv, pp. 137-46. 

, 1880. The Brachiopoda from the Inferior Oolite of Dorset and a portion of 

Somerset. Proc. Dorset N.F.C., vol. iv, pp. 1-52. 

, 1881. A Descriptive Catalogue of some of the Species of Ammonites from the 

Inferior Oolite of Dorset. Q.J.G.S., vol. xxxvii, pp. 588-608. 

, 1886. Notes on Jurassic [Inferior Oolite] Brachiopoda [Rhynchonella liostraca 

Buck, and Terebratula euides Buck.]. Geol. Mag. [3], vol. iii, pp. 217-19. 

, 1886-1907,1908. A Monograph of the Ammonites of the 4 Inferior Oolite Series'; 

and illustrations of Type Specimens of Inferior Oolite Ammonites (edited by the 

Secretary; 1908). 

, 1887. The Inferior Oolite between Andoversford and Bourton on the Water. 

Proc. Cots. N.F.C., vol. ix, pp. 108-35. 

, 1887. Some New Species of Brachiopoda from the Inferior Oolite of the 

Cotteswolds. Proc. Cots. N.F.C., vol. ix, pp. 38-43. 

, 1889. The Descent of Sonninia and Hammatoceras. Q.J.G.S., vol. xiv, 

pp.651-63. 

, 1890. The Relations of Dundry with the Dorset-Somerset and Cotteswold 

Areas during part of the Jurassic Period. Proc. Cots. N.F.C., vol. ix, pp. 374-87. 

, 1890. Some New Species of Brachiopoda from the Inferior Oolite of the Cotteswolds. 

Proc. Cots. N.F.C., vol. ix, pp. 38-43.

INFERIOR OOLITE 643 

BUCKMAN, S. S., 1892. The Sections [of Inferior Oolite] exposed between Andoversford 

and Chedworth: a Comparison with Similar Srata upon the Banbury Line. 

Proc. Cots. N.F.C., vol. x, pp. 94-100. 

, 1892. The Morphology of 'Stephanoceras' zigzag. Q.J.G.S., vol. xlviii, 

PP- 447-52. 

, 1893. The Bajocian of the Sherborne District. Q.J.G.S., vol. xlix, pp. 479-522. 

, 1893. 'The Top of the Inferior Oolite' and a Correlation of 'Inferior Oolite' 

Deposits. Proc. Dorset N.F.C., vol. xiv, pp. 37-43. 

, 1895. The Bajocian of the Mid-Cotteswolds. Q.J.G.S., vol. Ii, pp. 388-462. 

, 1897. Deposits of the Bajocian Age in the Northern Cotteswolds; the Cleeve 

Hill Plateau. Q.J.G.S., vol. liii, pp. 607-29. 

, 1901. The Bajocian and Contiguous Deposits in the North Cotteswolds: the 

Main Hill-Mass. Q.J.G.S., vol. Ivii, pp. 126-55. 

, 1906. A Cotteswold Brachiopod [.Rhynchonella acutiplicata Brown]. Proc. Cots. 

N.F.C., vol. xv, pp. 209-14. 

, 1910. Certain Jurassic (Lias-[Inferior] Oolite) Strata of South Dorset, and 

their Correlation. Q.J.G.S., vol. lxvi, pp. 52-89. 

, 1910. Certain Jurassic (Inferior Oolite) Species of Ammonites and Brachiopoda. 

Q.J.G.S., vol. lxvi, pp. 90-110. 

, 1912. Ammonites from the Scarborough Limestone. Appendix to paper by 

L. Richardson, Proc. Yorks. Geol. Soc., N.S., vol. xvii, pp. 205-8. 

BUCKMAN, S. S., & WILSON, E., 1896. Dundry Hill: its Upper Portion, or the Beds 

Marked as Inferior Oolite (g 5 ) in the Maps of the Geological Survey. Q.J.G.S., 

vol. Iii, pp. 669-720. 

BUNBURY, C. J. F., 1851. On some Fossil Plants from the Jurassic Strata [Lower and 

Middle Estuarines] of the Yorkshire Coast. Q.J.G.S., vol. vii, pp. 179-94. 

CRICK, G. C., 1898. Descriptions of new or imperfectly known Species of Nautilus 

from the Inferior Oolite, preserved in the British Museum. Proc. Malacol. Soc., 

vol. iii, pp. 117-39. 

DAVIDSON, T., 1877. On the Species of Brachiopoda that occur in the Inferior Oolite 

at Bradford Abbas and its Vicinity. Proc. Dorset N.F.C., vol. i, pp. 73-88. 

DUNCAN, P. M., 1886. On a New Species of Axosmilia (A. elongata) from the Pea 

Grit of the Inferior Oolite. Geol. Mag. [3], vol. iii, pp. 340-2. 

EVANS, J., 1879. On some Fossils from the Northampton Sands. Rept. Brit. Assoc. 

for 1878, pp. 534-5. 

GRAY, J. W., 1925. Leckhampton Hill, Gloucestershire: The Wellington Quarry and 

other Sections. Proc. Cots. N.F.C., vol. xxii, pp. 33-42. 

HALLE, T. G., 1912. On the Fructification of Jurassic Fern Leaves of the Cladophlebis 

denticulata; and Cloughtoniay a Problematic Fossil Plant from the Yorkshire [Inferior 

Oolite]. Arkiv fur Botanik, vol. x, nos. 14, 15. Stockholm. 

, 1913. On Upright Equisetites Stems in the Oolitic [Lower Estuarine] Sandstone 

in Yorkshire [Peak]. Geol. Mag. [5], vol. x, pp. 3-7, with note on Stratigraphical 

Position by P. F. Kendall. 

HAWELL, J., 1903. On an Oolitic Plant Bed in North Cleveland. Naturalist, p. 312. 

, 1904. Bajocian Plant Beds of Yorkshire. Proc. Cleveland N.F.C. for 1902, 

pp. 229-34. 

HEPWORTH, E., 1923. The [Lower] Estuarine Series of the Yorkshire Coast. Trans. 

Leeds Geol. Soc., part xix, pp. 24-8. 

HOLL, H. B., 1863. On the Correlation of the several Subdivisions of the Inferior 

Oolite in the Middle and South of England. Q.J.G.S., vol. xix, pp. 306-17. 

HUDLESTON, W. H., 1874. The Yorkshire Oolites. Part I, The Lower Oolites: 

P.G.A., vol. iii, pp. 283-333. 

, 1887-96. A Monograph of the Inferior Oolite Gasteropoda. Pal. Soc. 

IBBETSON, L. L. B., 1847. On three Sections of the Oolitic Formations [chiefly 

Inferior Oolite] on the Great Western Railway at the West End of Sapperton 

Tunnel. Rept. Brit. Assoc. for 1846, p. 61. 

JACKSON, J. W., 1911. A New Species of Unio [U. kendalli] from the Yorkshire 

[Lower] Estuarine Series. Naturalist, 1911, pp. 211-14. 

JONES, J., i860. On Rhynchonella acuta and its Affinities. Proc. Cots. N.F.C., vol.ii, 

pp. 1-8.


KENDALL, P. F., 1908. Reptilian Footprints in the Lower Oolites at Saltvvick. 

Naturalist, p. 384. 

KENT, A. U., & WALKER, J. F., 1879. The Finding of Terebratula morieri [in the 

Inferior Oolite] at Bradford Abbas, and on its Occurrence in England. Proc. 

Dorset N.F.C., vol. iii, pp. 39-47. 

LUCY, W. C., 1889. Remarks on the Dapple Bed of the Inferior Oolite at the Horsepools. 


LANE, G. J., 1909. Jurassic Plants from the Cleveland Hills. Proc. Cleveland N.F.C., 

vol. ii, pp. 172-3, also Naturalist, 1909, p. 81. [Lists from Carlton Bank, Marske 

and Upleatham.] 

, 1910. Notes on the Jurassic Flora of Cleveland. Proc. Cleveland N.F.C., 

vol. ii, p. 206. 

LANE, G.J. ,&SAUNDERS, T.W., 1910. Oolitic Plant Remains in Yorkshire. Naturalist, 

1910, p.15. 

LUCY, W. C., & TOMES, R. F., 1889. Notes on the Jurassic Rocks at Crickley Hill, 

with an Amended List of the Madreporaria. Proc. Cots. N.F.C., vol. ix, pp. 289-308. 

LYCETT, J., 1850. Tabular View of Fossil Shells from the Middle Division of the 

Inferior Oolite in Gloucestershire. Ann. Mag. Nat. Hist. [2], vol. vi, and Proc. 

Cots. N.F.C., vol. i, pp. 62-86. 

, 1853. On some New Species of Trigonia from the Inferior Oolite of the Cotteswolds, 

with Preliminary Remarks on that Genus. Proc. Cots. N.F.C., vol. i, 

pp. 246-61. 

, 1853. Note on the Gryphcea of the Bed called Gryphite Grit in the Cotteswolds. 

Proc. Cots. N.F.C., vol. i, pp. 235-6. 

MANSEL-PLEYDELL, J. C., 1881. Notes on a Cone [Araucaria cleminshawii] from the 

Inferior Oolite Beds of Sherborne. Proc. Dorset, N.F.C., vol. v, pp. 141-3. 

MOORE, C., 1855. On New Brachiopoda from the Inferior Oolite of Dundry, &c. 

Proc. Somerset Arch. Soc., vol. v, pp. 107-28. 

MURCHISON, R. I., 1832. On the Occurrence of Stems of Fossil Plants in Vertical 

Positions in the Sandstone of the Inferior Oolite in the Cleveland Hills. Proc. Geol. 

Soc., vol. i, p. 391. 

MURRAY, P., 1828. Account of a Deposit of Fossil Plants discovered in the Coal 

Formation near Scarborough [Gristhorpe Plant Bed]. Edin. New. Phil. Journ., 

vol. v, pp. 311-17. 

NEWBITT, T., 1911. Catalogue of Oolite Fossil Plants found in the Whitby Cliffs, 

together with the Museum Numbers of the Specimens exhibited in the Whitby 

Museum. Rept. Whitby Lit. Phil. Soc., no. 88, for 1910, pp. 23-6. 

PARIS, E. T., 191 I. Notes on some Yorkshire Echinoids [from the Bajocian]. Appendix 

to paper by L. Richardson, Proc. Yorks. Geol. Soc., N.S., vol. xvii, pp. 213-15. 

PARIS, E. T., & RICHARDSON, L., 1915. Some Inferior Oolite Pectinidae. Q.J.G.S., 

vol. lxxi, pp. 521-35. 

RICHARDSON, L., 1902. On the Sequence of the Inferior Oolite Deposits at Bredon 

Hill, Worcestershire. Geol. Mag. [4], vol. ix, pp. 513-14. 

, 1903. On a Section at Cowley, near Cheltenham, and its Bearing upon the 

Interpretation of the Bajocian Denudation. Q.J.G.S., vol. lix, pp. 382-9. 

, 1905. Excursion to Leckhampton Hill. Proc. Cots. N.F.C., vol. xv, pp. 182-9. 

, 1907. On the 'Top-Beds' of the Inferior Oolite at Rodborough Hill, near Stroud. 

Proc. Cots. N.F.C., vol. xvi, pp. 71-80. 

, 1907. The Inferior Oolite and Contiguous Deposits of the Bath-Doulting 

District; and appendix on their correlation with those of Dorset by S. S. Buckman. 

Q.J.G.S., vol. Ixiii, pp. 383-426. 

, 1907. The Inferior Oolite and Contiguous Deposits of the District between 

Rissington and Burford. Q.J.G.S., vol. Ixiii, pp. 437-44. 

, 1907. On New Species of Amberleya and of Spirorbis (from the Upper Inferior 

Oolite). Q.J.G.S., vol. Ixiii, pp. 434-6. 

, 1907. On the Stratigraphical Position of the Beds [Inferior Oolite] from 

which Prosopon richardsoni H. Woodward was obtained. Geol. Mag. [5], vol. iv, 

pp.82-4. 

• , 1908. On the Phyllis Collection of Inferior Oolite Fossils from Doulting. Geol. 

Mag. [5], vol. v, pp. 509-17-

INFERIOR OOLITE 645 

RICHARDSON, L., 1908. The Geology of Ebrington Hill, North Cotteswolds. Proc. 

Cots. N.F.C., vol. xvi, pp. 129-34. 

, 1909. Note on Pollicipes aalensis Richardson. Proc. Cots. N.F.C., vol. xvi, p. 265. 

, 1910. The Inferior Oolite and Contiguous Deposits of the South Cotteswolds. 

Proc. Cots. N.F.C., vol. xvii, pp. 63-136. 

, 1910. On the Sections of Inferior Oolite on the Midford-Camerton Section of 

the Limpley Stoke Railway, Somerset. P.G.A., vol. xxi, pp. 97-100. 

, 1910. On the Stratigraphical Distribution of the Inferior Oolite Vertebrates 

of the Cotteswold Hills and the Bath-Doulting District. Geol. Mag. [5], vol. vii, 

pp. 272-4. 

, 1910. Excursion to Stonesfield and Fawler. [Description of Inferior Oolite and 

Upper and Middle Lias.] Proc. Cots. N.F.C., vol. xvii, pp. 28-31. 

, 1911. The Inferior Oolite and Contiguous Deposits of the Chipping Norton 

District, Oxfordshire. Proc. Cots. N.F.C., vol. xvii, pp. 195-231. 

, 1911. The Lower Oolitic Rocks of Yorkshire. Proc. Yorks. Geol. Soc., N.S., 

vol. xvii, pp. 184-204. 

, 1914. The Chronological Succession of the Echinoid Faunas in the Inferior 

Oolite Rocks of the Stonesfield-Burton Bradstock District. Proc. Cots. N.F.C., 

vol. xviii, pp. 251-6. 

, 1915. The Inferior Oolite and Contiguous Deposits of the Doulting-Milborne- 

Port District (Somerset). Q.J.G.S., vol. lxxi, pp. 473-520. 

, 1916. On the Stratigraphical Distribution of the Inferior Oolite Vertebrates of 

the Cotteswold Hills and the Bath-Burton Bradstock District. Proc. Dorset N.F.C., 


, 1918. The Inferior Oolite and Contiguous Deposits of the Crewkerne District, 

Somerset. Q.J.G.S., vol. lxxiv, pp. 145-73. 

, 1920. Remains of Macrurous and Brachyurous Crustacea in the Inferior Oolite 

of the Stonesfield (Oxon.)-Burton Bradstock (Dorset) District. Proc. Cots. N.F.C., 

vol. xx, pp. 243-4. 

, 1922. Certain Aalenian-Vesulian Strata of the Banbury District, Oxfordshire. 

Proc. Cots. N.F.C., vol. xxi, pp. 109-32. 

, 1923. Certain Jurassic (Aalenian-Vesulian) Strata of Southern Northamptonshire. 

P.G.A., vol. xxxiv, pp. 97-113. 

, 1926. Certain Jurassic Strata of the Duston Area, Northamptonshire. Proc. 

Cots. N.F.C., vol. xxii, pp. 137-52. 

, 1928-30. The Inferior Oolite and Contiguous Deposits of the Burton Bradstock 

-Broad Windsor District, Dorset. Proc. Cots. N.F.C., vol. xxiii, pp. 35-68, 149-86, 

and 253-64. 

, 1932. The Inferior Oolite and Contiguous Deposits of the Sherborne District, 

Dorset. Proc. Cots. N.F.C., vol. xxiv, pp. 35-85. 

RICHARDSON, L., & PARIS, E. T., 1908-13. On the Stratigraphical and Geographical 

Distribution of the Inferior Oolite Echinoids of the West of England. Proc. Cots. 

N.F.C., 1908, vol. xvi, pp. 151-89, and Supplement, ibid. 1913, vol. xviii, pp. 73-82. 

RICHARDSON, L., & THACKER, A. G., 1920. On the Stratigraphical and Geographical 

Distribution of the Sponges of the Inferior Oolite of the West of England. P.G.A., 

vol. xxxi, pp. 161-86. 

RICHARDSON, L., & UPTON, C., 1913. Some Inferior Oolite Brachiopoda. Proc. Cots. 

N.F.C., vol. xviii, pp. 47-58. 

SEWARD, A. C., 1903. On the Occurrence of Dictyozamites in [the Lower Estuarine 

Series of Yorks.], with remarks on European Mesozoic Floras. Q.J.G.S., vol. lix, 

pp.217-33. 

, 1906. Jurassic Plants from the [Inferior Oolite] Rocks of East Yorkshire. Rept. 

Brit. Assoc. for 1905, p. 568; and Geol. Mag. [5], vol. iii, p. 518. 

SHARP, S., 1869. Notes on the Northampton Oolites. Geol. Mag., vol. vi, pp. 446-8. 

, 1870-3. The Oolites of Northamptonshire. Q.J.G.S., vol. xxvi, pp. 354-93 

(and appendix on a starfish by T. Wright); and ibid., vol. xxix, pp. 225-302. 

, 1874. Sketch of the Geology of Northamptonshire. P.G.A., vol. iii, pp. 243-52. 

SKERL, J. G. A., 1926-8. The Petrography of some Jurassic 'Sands' from the North 

Cotteswolds. Proc. Cots. N.F.C., vol. xxii, pp. 153-60; and 'Rocks', ibid., pp. 281-6, 

and vol. xxiii, pp. 25-30.


SKERL, J. G. A., 1927. Notes on the Petrography of the Northampton Ironstone. 

P.G.A., vol. xxxviii, pp. 375-94. 

SOLLAS, W. J., 1883. Descriptions of Fossil Sponges from the Inferior Oolite, with 

a Notice of some from the Great Oolite. Q.J.G.S., vol. xxxix, pp. 541-54. 

STODDART, W., 1867. Geology of Dundry Hill. Proc. Bristol Nat. Soc. [2], 

vol. ii, pp. 29-33. 

STODDART, W., 1877. List of Characteristic Fossils of the Dundry Oolite. Proc. Cots. 

N.F.C., vol. vi, pp. 297-300. 

TAWNEY, E. B., 1874. Museum Notes: Dundry Gasteropoda. Proc. Bristol Nat. Soc. 

[2], vol. i, p. 2. 

THOMAS, H. D., 1930. On a New Sponge [Stelletta] from the Inferior Oolite of 

Gloucestershire. Proc. Cots. N.F.C., vol. xxiii, pp. 265-7. 

THOMAS, H. H., 191 I. On the Spores of some Jurassic Ferns [in the Lower Estuarine 

Series of Yorkshire]. Proc. Camb. Phil. Soc., vol. xvi, pp. 384-8. Abstracts in 

Nature, p. 472, and Naturalist, p. 347. 

, 1911-13. Recent Researches on the Jurassic Plants of East Yorkshire [Mainly 

Inferior Oolite]. Naturalist, 1911, pp. 409-10, and Rept. Brit. Assoc. for 191 x 

(Portsmouth), pp. 569-70; and ibid, for 1912 (Dundee), pp. 294-5. 

, 1911-22. On some New and Rare Jurassic Plants from [the Lower and Middle 

Estuarine Series of] Yorkshire: 

(1) Eretmophyllum, a new type of Ginkgoalean leaf. Proc. Camb. Phil. Soc., 

vol. xvii, pp. 256-62. 

(2) The male flower of Williamsonia gigas; ibid., vol. xviii, pp. 105-10. 

(3) Fertile specimens of Dictyophyilum rugosum; ibid., vol. xxi, pp. 111-16. 

, 1912. Stachypteris hallei; a new Jurassic Fern [from the Lower Estuarine Series 

of Yorkshire]. Proc. Camb. Phil. Soc., vol. xvi, pp. 610-14. 

, 1913. The Jurassic Plant-Beds of Roseberry Topping [Yorkshire]. Naturalist, 

1913, p.198. 

, 1913. The Fossil Flora of the Cleveland District of Yorkshire: (1) The Flora of 

the Marske Quarry [Lower Estuarine Series]; with notes on the Stratigraphy by 

G. J. Lane. Q.J.G.S., vol. lxix, pp. 223-51. 

, 1915. The Thinnfeldia Leaf-Bed of Roseberry Topping. Naturalist, 1915, 

p. 7. 

, 1915. On Williamsoniella, a New Type of Bennettitalean Flower [from the 

Middle Estuarine Plant-Bed of Gristhorpe]. Phil. Trans. Roy. Soc., vol. ccvii B, 

pp. 113-48. 

, 1925. The Caytoniales, a New Group of Angiospermous Plants from the 

[Middle Estuarine Series] of Yorkshire. Phil. Trans. Roy. Soc., vol. ccxiii B, 

pp. 299-363. 

THOMPSON, B., 1921-8. The Northampton Sand of Northamptonshire. Journ. 

Northants. N.H.S., 1921-8. Reprinted in book form 1928; Dulau, London. 

, 1924. The Inferior Oolite Sequence in Northamptonshire and Parts of Oxfordshire. 

P.G.A., vol. xxxv, pp. 67-76. 

TOMES, R. F., 1878. A List of the Madreporaria of Crickley Hill, Gloucestershire, 

with Descriptions of some New Species. Geol. Mag. [2], vol. v, pp. 297-305. 

, 1879. On the Fossil Corals obtained from the [Inferior] Oolite of the Railway 

Cuttings near Hook Norton, Oxfordshire. P.G.A., vol. vi, pp. 152-65. 

, 1882. On the Madreporaria of the Inferior Oolite of the Neighbourhood of 

Cheltenham and Gloucester. Q.J.G.S., vol. xxxviii, pp. 409-50. 

, 1886. On some New or Imperfectly Known Madreporaria from the Inferior 

Oolite of Oxfordshire, Gloucestershire and Dorsetshire. Geol. Mag. [3], vol. iii, 

PP. 385-98, 443-52. 

, 1889. Notes on an Amended List of Madreporaria of Crickley Hill. Proc. Cots. 

N.F.C., vol. ix, pp. 300-7. 

TONKS, L. H., 1923. Recent Notes on the Dogger Sandstone of the Yorkshire Coast. 

Trans. Leeds Geol. Soc., part xix, pp. 29-33. 

UPTON, C., 1899-1905. Some Cotteswold Brachiopoda. Proc. Cots. N.F.C., vol. xiii, 

pp. 121-32, and vol. xv, pp. 82-92. 

WALFORD, E. A., 1883. On the Relation of the so-called 'Northampton Sand' of 

North Oxon. to the Clypeus Grit. Q.J.G.S., vol. xxxix, pp. 224-45.

INFERIOR AND GREAT OOLITE 647 

WALFORD, E. A., 1889-94. On some Bryozoa from the Inferior Oolite of Shipton 

Gorge, Dorset. Q.J.G.S., vol. xlv, pp. 561-74 (1889), and vol. 1, pp. 72-8 (1894). 

WALKER, J. F., 1878. On the Occurrence of Terebratula Morieri in England. Geol. 

Mag. [4], vol. v, p. 552. 

WALKER, J. F., & BUCKMAN, S. S., 1889. On the Spinose Rhynchonellce (Genus 

Acanthothyris d'Orbigny) found in England. Rept. Yorks. Phil. Soc. for 1888, 

PP- 41-57- 

WEDD, C. B., 1920. Northampton (Inferior Oolite) Ironstone of Mid and South 

Lincolnshire, Rutland and Northamptonshire; in Lamplugh, Wedd & Pringle. 

Spec. Repts. Min. Resources Gt. Brit., vol. xii—Bedded Iron Ores, ch. vi, 

pp. 141-207. Mem. Geol. Surv. 

WETHERED, E. B., 1891. The Inferior Oolite of the Cotteswold Hills, with Special 

Reference to its Microscopical Structure. Q.J.G.S., vol. xlvii, pp. 550-70. 

WETHERED, E. B., & WITCHELL, E., 1886-7. The Pea-Grit of Leckhampton Hill. 

Geol. Mag. [3], vol. iii, p. 525, and vol. iv, pp. 46-7. 

WHIDBORNE, G. F., 1883. Notes on some Fossils, chiefly Mollusca, from the Inferior 

Oolite. Q.J.G.S., vol. xxxix, pp. 487-540. 

WILLIAMSON, W. C., 1855-70. On the Restoration of Zamites gigas from the Lower 

Sandstone and Shale of the Yorkshire Coast. Rept. Brit. Assoc. for 1854, p. 103, 

and Trans. Linn. Soc., vol. xxvi, 1870, p. 663. 

WITCHELL, E., 18S0. On a Section of Stroud Hill, and the Upper Ragstone Beds of 

the Cotteswolds. Proc. Cots. N.F.C., vol. vii, pp. 118-35. 

, 1886. On the Basement Beds of the Inferior Oolite of Gloucestershire. Q.J.G.S., 

vol. xlii, pp. 264-71. 

, 1886. On the Pisolite and the Basement Beds of the Inferior Oolite of the Cotteswolds. 

Proc. Cots. N.F.C., vol. viii, pp. 35-49. 

, 1887. The Pea Grit of Leckhampton Hill. Geol. Mag. [3], vol. iv, pp. 46-7. 

, 1890. On the Genus Nerincea and its Stratigraphical Distribution in the Cotteswolds. 


WITHERS, T. H., 191 I. On the Occurrence of Pollicipes [a Cirripede] in the Inferior 

Oolite. Proc. Cots. N.F.C., vol. xvii, p. 275 (with list of references). 

WOODWARD, H. B., 1908. The New Great Western Branch Railway from Camerton to 

Limpley Stoke, Somerset. Sum. Prog. Geol. Surv. for 1907, pp. 155-7. 

WRIGHT, T., i860. On the Subdivisions of the Inferior Oolite in the South of 

England, compared with the Equivalent Beds of that Formation in Yorkshire. 

Q.J.G.S., vol. xvi, pp. 1-48. 

WRIGHT, T., & LYCETT, J., 1853. Contributions to the Palaeontology of Gloucestershire 

:—On the Strombidce of the Oolites, with the Description of a New and Remarkable 

Pteroceras. Proc. Cots. N.F.C., vol. i, pp. 115-19. 

GREAT OOLITE SERIES AND CORNBRASH 

ARKELL, W. J., 1931. The Upper Great Oolite, Bradford Beds and Forest Marble of 

South Oxfordshire, and the Succession of Gastropod Faunas in the Great Oolite. 

Q.J.G.S., vol. lxxxvii, pp. 563-629. 

, 1933. The Geological Results of a Boring into the Great Oolite at Latton, near 

Cricklade, Wilts. Proc. Cots. N.F.C., vol. xxv (in the press). 

, 1933. A New Section of the Upper Great Oolite at Bladon, near Woodstock, 

Oxon. P.G.A., vol. xliv (in the press). 

ARKELL, W. J., RICHARDSON, L., & PRINGLE, J., 1933. The Lower Oolites exposed in 

the Ardley and Fritwell Railway-cuttings, Oxon. P.G.A., vol. xliv (in the press). 

BARROW, G., 1908-9. The New Great Western Railway from Ashendon to Aynho, 

near Banbury. Sum. Prog. Geol. Surv. for 1907, pp. 141-54, and P.G.A., vol. xxi, 

1909, PP- 35-45- 

BEAN, W., 1836. Description and Figures of Unio distortus and Cypris concentrica from 

the Upper Sandstone and Shale of Scarborough. Ann. Mag. Nat. Hist., vol. ix, 

PP-376-7. 

, 1839. Catalogue of Fossils in the Cornbrash of Scarborough. Ann. Mag. Nat. 

Hist., N.S., vol. iii, pp. 57-62. 

BLACK, M., 1923. Fossil Plants from the Upper Estuarine Series. Naturalist, p. 57.


BLACK, M., 1928. 'Washouts' in the Estuarine Series of Yorkshire. Geol. Mag., 

vol. lxv, pp. 301-7. 

, 1929. Drifted Plant Beds of the Upper Estuarine Series of Yorkshire. Q.J.G.S., 

vol. lxxxv, pp. 389-437. 

BLAKE, C. C., 1863. On Chelonian Scutes from the Stonesfield Slate. Geologist, 

vol. vi, pp. 183-4. 

BLAKE, J. F., 1905-7. A Monograph of the Fauna of the Cornbrash. Pal. Soc. 

[incomplete]. 

BRODERIP, W. J., & FITTON, W. H., 1828. Observations on the Jaw of a Mammiferous 

Animal found in the Stonesfield Slate, and on the Strata from whence the Fossil . . . 

was obtained. Zoological Journal, vol. iii, pp. 408-18. 

BRODIE, P. B., & BUCKMAN, J., 1845. On the Stonesfield Slate of the Cotteswold Hills. 

Q.J.G.S., vol. i, pp. 220-5 ; and Proc. Geol. Soc., vol. iv, pp. 437-42. 

BROWETT, A., 1889. The Bath Oolite and Method of Quarrying it. Midland Naturalist, 

vol. xii, pp. 187-90. 

BUCKLAND, W., 1824. Notice on the Megalosaurus, or Great Fossil Lizard of Stonesfield. 

Trans. Geol. Soc. [2], vol. i, pp. 390-6. 

, 1838. On the Discovery of a Fossil Wing of a Neuropterous Insect in the 

Stonesfield Slate. Proc. Geol. Soc., vol. ii, p. 688. 

BUCKMAN, J., 1853. On the Cornbrash of the Neighbourhood of Cirencester. Proc. 

Cots. N.F.C., vol. i, pp. 262-7, and Ann. Mag. Nat. Hist. [2], vol. xii, pp. 324-9. 

, 1854. On the Cornbrash of Gloucestershire and part of Wilts. Rept. Brit. 

Assoc. for 1853, pp. 50-1. 

, i860. On some Fossil Reptilian Eggs from the Great Oolite of Cirencester. 

Q.J.G.S., vol. xvi, pp. 107-10. 

BUCKMAN, S. S., 1922. Jurassic Chronology, II: Watton Cliff, between Eypesmouth 

and West Bay. Q.J.G.S., vol. lxxviii, pp. 380-9. 

, 1927. Jurassic Chronology, III: Some Faunal Horizons in Cornbrash. Q.J.G.S., 

vol. lxxxiii, pp. 1-37. 

, 1927. Troll Quarry, Thornford, Dorset [Fuller's Earth Rock]. T.A., vol. vi, 

pp. 50-1. 

BUTLER, A. G., 1873. On a Fossil Butterfly belonging to the Family Nymphalidce, 

from the Stonesfield Slate near Oxford. Geol. Mag., vol. x, pp. 2, 3. 

CARPENTER, P. H., 1882. On some New or Little-Known Jurassic Crinoids [Great 

Oolite and Kellaways Rock]. Q.J.G.S., vol. xxxviii, pp. 29-43. 

CARRUTHERS, W., 1867. On an Aroideous Fruit from the Stonesfield Slate. Geol. 

Mag., vol. iv, pp. 146-7. 

1871. On some Supposed Vegetable Fossils [Reptilian eggs from Stonesfield]. 

Q.J.G.S., vol. xxvii, pp. 443~9- 

COOKE, J. H., 1896. A Section in the Lower Oolites [Cornbrash and Upper Estuarine 

Series] of Scarborough. Naturalist, pp. 289-92. 

COTTERELL, T. S., 1905. Bath Stone. Journ. Brit. Arch. Assoc., N.S., vol. xi, 

pp. 49-58. 

CUNNINGTON, W., i860. On the Bradford Clay and its Fossils. Wilts. Arch. N.H. 

Mag., vol. vi, pp. 1-10. 

DOUGLAS, J. A., & ARKELL, W. J., 1928-32. The Stratigraphical Distribution of 

the Cornbrash. I. The South-Western Area. Q.J.G.S., vol. lxxxiv, pp. 117-78. 

II. The North-Eastern Area, ibid., vol. Ixxxviii, pp. 112-70. 

DRAKE, H.C., 1910. Asteracanthus in the Yorkshire Cornbrash. Naturalist,pp. 141-2. 

FORBES, E., 1851. On the Estuary Beds and the Oxford Clay at Loch Staffin in Skye. 

Q.J.G.S., vol. vii, pp. 104-13. 

GAUDRY, A., 1853. Note sur Stonesfield, pres Oxford (Angleterre). Bull. Soc. geol. 

France [2], vol. x, pp. 591-6. 

GOODRICH, E. S., 1894. On the Fossil Mammalia of the Stonesfield Slate. Quart. 

Journ. Micros, Sci., vol. xxxv, pp. 407-31. 

GREGSON, C. S., 1863. On a Fossil Elytron from the Stonesfield Slate. Proc. Liverpool 

Geol. Soc., Session 3, p. 8. 

HARKER, A., 1890. On the Sections in the Forest Marble and Great Oolite formations 

exposed by the New Railway from Cirencester to Chedworth. Proc. Cots. N.F.C., 

vol. x, pp. 82-94.

GREAT OOLITE 649 

HORTON, W. S., i860. On the Geology of the Stonesfield Slate and its Associate 

Formations. The Geologist, vol. iii, pp. 249-58. 

HUXLEY, T. H., 1859. On Rhamphorhynchus bucklandi, a Pterosaurian from the Stonesfield 

Slate. Q.J.G.S., vol. xv, pp. 658-70. 

JACKSON, J. W., 1909. On the Type-Specimen of Pseudomelania vittata (Phillips) 

[Cornbrash of Scarborough; now at Manchester]. Geol. Mag. [5], vol. vi, pp. 542-3. 

, 1911. On Unio distortus Bean and Alasmodon vetustus Brown, from the Upper 

Estuarine Beds of Gristhorpe, Yorks. Naturalist, 1911, pp. 104-7, 119-22. 

JONES, T. R., & SHERBORN, C. D., 1888. On some Ostracoda from the Fuller's Earth 

Oolite and Bradford Clay. Proc. Bath N.H. and Antiq. F.C., vol. vi, pp. 249-78. 

JUDD, J. W., 1871. On the Anomalous Mode of Growth of Certain Fossil Oysters 

[Ostrea undosa (Phil.) from the Cornbrash]. Geol. Mag., vol. viii, pp. 355-9. 

LANG, W. D., 1907. The Evolution of Estomatopora dichotomoides (d'Orbigny) [from 

the Cornbrash of Scarborough]. Geol. Mag. [5], vol. iv, pp. 20-4. 

LECKENBY, J., 1864. On the Sandstones and Shales of the Oolites of Scarborough, 

with Descriptions of some New Species of Fossil Plants. Q.J.G.S., vol. xx, 

pp. 74-82. 

LEE, G. W., 1913. The Occurrence of Oil-Shale among the Jurassic Rocks [Great 

Estuarine Series] of Raasay and Skye. Nature, 1913, p. 169. 

LYCETT, J., 1848. On the Mineral Character and Fossil Conchology of the Great 

Oolite, as it occurs in the Neighbourhood of Minchinhampton. Q.J.G.S., vol. iv, 

pp.181-91. 

, 1863. A Supplementary Monograph on the Mollusca from the Stonesfield 

Slate, Great Oolite, Forest Marble, and Cornbrash. Pal. Soc. 

MACKIE, S. J., 1863. Turtles in the Stonesfield Slate. Geologist, vol. vi, pp. 41-3. 

MANSEL-PLEYDELL, J. C., 1877. Notes on a Gavial Skull [Steneosaurus stephani] from 

the Cornbrash of Closworth. Proc. Dorset N.F.C., vol. i, pp. 28-32. 

MORRIS, J., 1857. Descriptions of the Figured Species of [Great Oolite] Fossils; 

in E. Hull's 'Geology of the Country around Cheltenham', Mem. Geol. Surv., 

pp. 103-4, anc * plate. 

MORRIS, J., & LYCETT, J., 1850-3. A Monograph of the Mollusca from the Great 

Oolite, chiefly from Minchinhampton and the Coast of Yorkshire. Pal. Soc. 

MURCHISON, R. I., 1843. Observations on the Occurrence of Freshwater Beds in the 

Oolitic Deposits of Brora, Sutherland, &c. Proc. Geol. Soc., vol. iv, pp. 173-6. 

ODLING, M., 1913. The Bathonian Rocks of the Oxford District. Q.J.G.S., vol. lxix, 

pp.484-513. 

OWEN, R., 1838. Description of the Remains of Marsupial Mammalia from the Stonesfield 

Slate. Proc. Geol. Soc., vol. iii, pp. 17-21. 

, 1841. A Description of a Portion of the Skeleton of the Cetiosaurus, a gigantic 

extinct Saurian Reptile. Proc. Geol. Soc., vol. iii, pp. 457-62. 

, 1883. On the Skull of Megalosaurus. Q.J.G.S., vol. xxxix, pp. 334-47. 

PARIS, E. T., 191 I. New Lamellibranchs (Gervillia and Perna) from the Neaeran 

Beds. Proc. Cots. N.F.C., vol. xvii, pp. 233-5. 

, 1911. Notes on some Species of Gervillia from the Lower and Middle Jurassic 

Rocks of Gloucestershire, and from the Scarborough Limestone. Proc. Cots. N.F.C., 

vol. xvii, pp. 237-56. 

PHILLIPS, J., i860. On some Sections of the Strata near Oxford. I. The Great Oolite 

in the Valley of the Cherwell. Q.J.G.S., vol. xvi, pp. 115-19. 

, 1866. Oxford Fossils [Dragon Flies from Stonesfield]. Geol. Mag., vol. iii, 

PP. 97-9. 

PLATNAUER, H. M., 1887. On the Occurrence of Strophodus rigauxi Sauv. in the Yorkshire 

Cornbrash. Rept. Yorks. Phil. Soc. for 1886, pp. 36-40. 

PREVOST, C., 1825. Observations sur les schistes calcaires oolitiques de Stonesfield en 

Angle terr e, dans lesquels ont ete trouv^s plusieurs ossemens fossiles de mammiferes. 

Ann. Sci. Nat. [1], vol. iv, p. 389 and plates. 

PRINGLE, J., 1909-10. On a Boring in the Fullonian and Inferior Oolite at Stowell, 

Somerset. Sum. Prog. Geol. Surv. for 1908, pp. 83-6, and for 1909, pp. 68-70. 

RICHARDSON, L., 1903. Notes on a Section of Great Oolite Beds [Chipping Norton 

Limestone] at Condicote, near Stow on the Wold. Geol. Mag. [4], vol. x, 

p. 404.


RICHARDSON, L1910. On a Fuller's Earth Section at Combe Hay, near Bath. 

P.G.A., vol. xxi, pp. 425-8. 

, 1910. The Great Oolite Section at Groves' Quarry, Milton-under-Wychwood. 

Geol. Mag. [4], vol. vii, pp. 537~42. 

, 1911. On the Sections of Forest Marble and Great Oolite on the Railway 

between Cirencester and Chedworth, Gloucestershire. P.G.A., vol. xxii, pp. 95- 

, 1925. A Boring at Lewis Lane, Cirencester [Great Oolite]. P.G.A., vol. xxxvi, 

PP- 93-9; an d Proc. Cots. N.F.C., vol. xii, p. 53. 

, 1925. Excursion to the North Cotteswolds [Stonesfield Slate, Neceran Beds and 

Chipping Norton Limestone]. Proc. Cots. N.F.C., vol. xxii, pp. 67-73. 

, 1930. Excursion to the Mid Cotteswolds [Great Oolite and Forest Marble]. 

Proc. Cots. N.F.C., vol. xxiii, pp. 209-13. 

, 1930. The Fosse Lime and Limestone Quarry and Works [in Great Oolite]. 

Proc. Cots. N.F.C., vol. xxiii, pp. 269-72. 

RICHARDSON, L., & ARKELL, W. J. The Fuller's Earth of England [in preparation]. 

RICHARDSON, L., & WALKER, J. F., 1907. Remarks on the Brachiopoda from the 

Fuller's Earth. Q.J.G.S., vol. Ixiii, pp. 426-34. 

SEELEY, H. G., 1880. On Rhamphocephalus prestwichi Seeley, an Ornithosaurian from 

the Stonesfield Slate of Kineton, Glos. Q.J.G.S., vol. xxxvi, pp. 27-35. 

STOPES, M. C., 1907. The Flora of the Inferior [Great] Oolite of Brora, Sutherland. 

Q.J.G.S., vol. Ixiii, pp. 375"82. 

TATE, R., 1870. The Fuller's Earth in the South-West of England. Quart. Journ. Sci., 

vol. vii, pp. 68-71. 

TAUNTON, J. A., 1872. Sapperton Tunnel on the Thames and Severn Canal. Proc. 

Cots. N.F.C., vol. v, pp. 255-70. 

THOMPSON, B., 1891. The Oolitic Rocks at Stowe-Nine-Churches. Journ. Northants 

N.H.S., vol. vi, pp. 295-310. 

, 1924. The Geology of Roade Cutting [near Blisworth, Northants]. Geol.Mag., 

vol. lxi, pp. 210-18. 

, 1930. The Upper Estuarine Series of Northamptonshire and Northern Oxfordshire. 

Q.J.G.S., vol. lxxxvi, pp. 430-62. 

TOMES, R. F., 1883. On the Fossil Madreporaria of the Great Oolite of the Counties 

of Gloucester and Oxford. Q.J.G.S., vol. xxxix, pp. 168-96. 

, 1885. On some new or imperfectly known Madreporaria from the Great Oolite 

of the Counties of Oxford, Gloucester and Somerset. Q.J.G.S., vol. xii, pp. 170-90. 

VERSEY, H. C., 1928. Cornbrash at Kepwick, N.E. Yorkshire. Naturalist, pp. 117-18. 

VINE, G. R., 1892. Notes on the Polyzoa, Stromatopora and Proboscina Groups, from 

the Cornbrash of Thrapston, Northants. Proc. Yorks. Geol. Soc., N.S., vol. xii, 

PP. 247-58. 

WALFORD, E. A., 1883. On some Crinoidal and other Beds in the Great Oolite of 

Gloucestershire, and their probable equivalents in North Oxfordshire. Proc. 

Warwicks. N.F.C. for 1882, pp. 20-7. 

, 1895-7. Stonesfield Slate. Report of the Committee appointed to open further 

sections in the Neighbourhood of Stonesfield in order to show the relationship of the 

Stonesfield Slate to the underlying and overlying strata. Rept. Brit. Assoc. for 1894 

(Oxford), pp. 304-6; 1895 (Ipswich), p. 415; 1896 (Liverpool), p. 356. 

, 1906. On some New Oolitic Strata in North Oxfordshire. Buckingham (and 

abstract in Q.J.G.S., vol. lxi, 1905, p. 440). 

, 1917. The Lower Oolite of North Oxfordshire. Banbury. 

WELCH, F. B. A., 1926. On the Further Extension of the Great Oolite in the North 

Cotteswolds. Proc. Cots. N.F.C., vol. xxii, pp. 219-38. 

WESTWOOD, J. O., 1854. Fossil Beetle and Dragon-fly from the Stonesfield Slate; in 

'Contributions to Fossil Entomology', Q.J.G.S., vol. x, pp. 379-81. 

WHITEAVES, J. F., 1861. On the Invertebrate Fauna of the Lower Oolites of Oxfordshire. 

Rept. Brit. Assoc. for i860 (Oxford). Trans. Sect., pp. 104-8. 

WINWOOD, H. H., 1913. Well Sinkings on Lansdown, Bath [in Great Oolite]. Proc. 

Cots. N.F.C., vol. xviii, pp. 83-7. 

WITCHELL, E., 1875. On a Bed of Fuller's Earth at Whiteshill, near Stroud. Proc. 

Cots. N.F.C., vol. vi, pp. 144-6.

OXFORD CLAY AND CORALLIAN 651 

WITCHELL, E., 1886. On the Forest Marble and Upper Beds of the Great Oolite between 

Nailsworth and Wotton-under-Edge. Proc.Cots.N.F.C., vol. viii,pp.265-80. 

WOOD, H. H., 1877. Notes on some Cornbrash Sections in Dorset. Proc. Cots. N.F.C., 

vol. i, pp. 22-7. 

WOODWARD, A. S., 1910. On a Skull of Megalosaurus from the Great Oolite of 

Minchinhampton (Gloucestershire). Q.J.G.S., vol. lxvi, pp. 111-15. 

WOODWARD, H., 1866. On the oldest known British Crab (Palceinachus longipes) from 

the Forest Marble, Malmesbury, Wilts. Q.J.G.S., vol. xxii, pp. 493-4. 

, 1868. On a New Brachyurous Crustacean (Prosopon mcimmillatum) from the 

Great Oolite, Stonesfield. Geol. Mag., vol. v, pp. 3-5. 

, 1890. On a New British Isopod (Cyclosphceroma trilobatuni) from the Great 

Oolite of Northampton. Geol. Mag. [3], vol. vii, pp. 529-33. 

WOODWARD, H. B., 1887. Note on some Pits near Chipping Norton, Oxon. Essex 

Naturalist, vol. i, pp. 265-6. 

, 1888-9. The Relations of the Great Oolite to the Forest Marble and Fuller's 

Earth in the South-West of England. Geol. Mag. [3], vol. v, pp. 467-8, and Rept. 

Brit. Assoc. for 1888, pp. 651-2. 

, 1902. Further Notes on the Cuttings along the South Wales Direct Railway 

[Forest Marble], Sum. Prog. Geol. Surv. for 1901, pp. 59-60. 

WRIGHT, T., 1882. On a New Species of Star Fish from the Forest Marble of Road, 

Wilts. (Uraster spinigera Wright). Proc. Cots. N.F.C., vol. viii, pp. 50-2. 

OXFORD CLAY AND CORALLIAN BEDS 

ANDREWS, C. W., 1895. Note on a Skeleton of a young Plesiosaur from the Oxford 

Clay of Peterborough. Geol. Mag. [4], vol. ii, pp. 241-3. 

, 1895. On the Development of the Shoulder-Girdle of a Plesiosaur (Cryptoclidus 

oxoniensis Phil.) from the Oxford Clay. Ann. Mag. Nat. Hist. [6], vol. xv, 

PP. 333-46. 

, 1909. On some New Steneosaurs from the Oxford Clay of Peterborough. Ann. 

Mag. Nat. Hist. [8], vol. iii, pp. 299-308. 

, 1910-13. A Descriptive Catalogue of the Marine Reptiles of the Oxford Clay, 

parts 1 and 2. Brit. Mus., London. 

, 1915. Note on a Mounted Skeleton of Opthalmosaurus icenicus Seeley [ex Leeds 

coll., Oxford Clay, Peterborough]. Geol. Mag. [6], vol. ii, pp. 145-6. 

ARKELL, W. J., 1926. Studies in the Corallian Lamellibranch Fauna of Oxford, Berks, 

and W T ilts. Part I—Limidae; Part II—Pectinidae. Geol. Mag., vol. lxiii, pp. 193- 

210 and 534-55. 

, 1926. The Corallian Period. Appendix to Chapter by W. J. Sollas in 'The 

Natural History of the Oxford District', edited by J. J. Wâlker. Oxford. 

, 1927. The Corallian Rocks of Oxford, Berks., and North Wilts. Phil. Trans. 

Roy. Soc., vol. ccxvi B, pp. 67-181. 

, 1927. The Red Down Boring, Highworth, and its Geological Significance; with 

notes on Neighbouring Wells. Wilts. Arch. Nat. Hist. Mag., vol. xliv, pp. 43-8. 

, 1928. Aspects of the Ecology of Certain Fossil Coral Reefs. Journ. of Ecology, 

vol. xvi, pp. 134-49. 

, 1929- . A Monograph of the British Corallian Lamellibranchia. Pal. Soc. 

, 1931. The Age of the Natica Band in the Corallian of Cumnor, near Oxford; 

and Descriptions of two New Sections at Cothill, Berks. P.G.A., vol. xlii, pp. 44-9. 

, 1932. An Unknown Kellaways Locality in Dorset? [The West Fleet near 

Langton Herring]. Geol. Mag., vol. lxix, pp. 44-5. 

BAILY, W. H., I860. Description of a New Pentacrinite from the Oxford Clay of 

Weymouth, Dorset. Ann. Mag. Nat. Hist. [3], vol. vi, pp. 25, 152. 

BLAKE, J. F., & HUDLESTON, W. H., 1877. The Corallian Rocks of England. Q.J.G.S., 

vol. xxxiii, pp. 260-405. 

BRINKMANN, R., 1929. Statistisch-biostratigraphische Untersuchungen an Mitteljurassischen 

Ammoniten iiber Artbegriff und Stammesentwicklung. [Kosmoceratids 

from the Oxford Clay of Peterborough.] Abh. Gesell. Wissensch. zu Gottingen, 

M.P. Klasse, N.F., vol. xiii, 3, pp. 1-250. [Review in Geol. Mag., vol. lxviii, 1931, 

PP. 373-6.]


BRINKMANN, R., 1929. Monographic der Gattung Kosmoceras. Abh. Gesell. 

Wissensch. Gottingen, M.P. Klasse, N.F., vol. xiii, 4, pp. 1-123- 

BUCKMAN, J., 1878. On some Slabs of Trigonia clavellata from Osmington Mills, 

Dorset. Proc. Dorset N.F C., vol. ii, pp. 19-20 and plate. 

BUCKMAN, S. S., 1913. The Kelloway Rock of Scarborough. Q.J.G.S., vol. lxix, 

pp.152-68. 

, 1924-7. Oxford Clay and Corallian Chronology. T.A., vol. v, 1924-5, 

PP. 34-55, 62-73; and vol. vi, 1927, p. 49. 

CAMERON, A. C. G., 1888. The Clays of Bedfordshire. P.G.A., vol. x, pp. 446-54. 

, 1890. Note on the Recent Exposures of Kellaways Rock at Bedford. Rept. Brit. 

Assoc. for 1889, pp. 577-8. 

, 1892. On the Continuity of the Kellaways Beds over extended Areas near 

Bedford. Geol. Mag. [3], vol. ix, pp. 66-71. 

CARTER, J., 1886. On the Decapod Crustaceans of the Oxford Clay. Q.J.G.S., 

vol. xiii, pp. 542-59- 

CHADWICK, S., 1886. Asteracanthus ornatissimus in the Corallian Oolite near Malton. 


COBBOLD, E. S., 1880. Notes on Strata exposed in laying out the Oxford Sewage Farm 

at Sandford-on-Thames. Q.J.G.S., vol. xxxvi, pp. 314-20. 

CRICK, W. D., 1887. Note on some Foraminifera from the Oxford Clay at Keyston, 

near Thrapston. Journ. Northants N.H.S., vol. iv, p. 232. 

CUNNINGTON, W., 1847. On the Fossil Cephalopoda from the Oxford Clay constituting 

the genus Belemnoteuthis (Pearce). Lond. Geol. Journ., pp. 97-9. 

DAVIES, A. M., 1907. The Kimeridge Clay and Corallian Rocks of the Neighbourhood 

of Brill (Buckinghamshire). Q.J.G.S., vol Ixiii, pp. 29-49. 

, 1916. The Zones of the Oxford and Ampthill Clays in Buckinghamshire and 

Bedfordshire. Geol. Mag., voh liii, pp. 395-400. 

, 1926. An Oolitic Rhaxella Chert from Little Hayes, South-East Essex. Geol. 

Mag., vol. Ixiii, pp. 273-4. 

DOUVILLE, R., 1912. Etudes sur les Cardioceratides de Dives, Villers-sur-Mer et 

quelques autres gisements, Mem. Soc. geol. France, vol. xix, no. 45, pp. 1-77. 

DRAKE, H C., 1907. Remains of Gyrodus from the Coral Rag of East Yorkshire. 

Trans. Hull Field Nat. Club, vol. iii, p. 290. 

, 1909. Remains of a Chimaeroid Fish from the Coral Rag of North Grimston. 


, 1911. Asteracanthus in the Coralline Oolite [at Seamer, Yorks.]. Naturalist, 

1911, p. 130. 

FOX-STRANGWAYS, C., 1897. Filey Bay and Brigg. Proc. Yorks. Geol. Soc., N.S., 

vol. xiii, pp. 338-45. 

HARKER, A., 1884. On a Remarkable Exposure of the Kellaways Rock in a Cutting 

[at South Cerney] near Cirencester. Proc. Cots. N.F.C., vol. viii, pp. 176-87. 

HEALEY, M., 1904. Notes on Upper Jurassic Ammonites, with Special Reference to 

Specimens in the University Museum, Oxford. [Mainly Corallian, 1 Kimeridge.] 

Q.J.G.S., vol. lx, pp. 54-64 

HINDE, G. J., 1890. On a new Genus of Siliceous Sponges from the Lower Calcareous 

Grit of Yorkshire [Rhaxella perforata]. Q.J.G.S., vol. xlvi, pp. 54-61. 

HUDLESTON, W. H., 1876-8. The Yorkshire Oolites [Middle Oolites: Oxford Clay 

and Corallian]. P.G.A., vol. iv, pp. 353-410 (1876), vol. v, pp. 407-94 (1878). 

, 1880-1. Contributions to the Palaeontology of the Yorkshire Oolites; Corallian 

Gastropoda. Geol. Mag. [2], vol. vii, pp. 241-8, 289-98, 391-404, 481-8, 529-38, 

and vol. viii, pp. 49-59, 119-31. 

1885. The Geology of Malton and Neighbourhood. Ann. Rept. Malton Nat. 

Soc., no. 2, for 1884-5, PP« 5~"3 0 - 

JACKSON, J. W., 1911. Strophodus teeth in the Corallian Beds of Malton. Naturalist, 

I9II,P. 151. 

KEEPING, W., 1878. On Pelanechinus, a new Genus of Sea-Urchins from the Coral Rag. 

Q.J.G.S., vol. xxxiv, pp. 924-30. 

KEEPING, W., & MIDDLEMISS, C. S., 1883. On some New Railway Sections and 

other Rock Exposures in the District of Cave, Yorkshire. Geol. Mag. [2], vol. x, 

pp.215-21.

OXFORD CLAY AND CORALLIAN 653 

KENDALL, P. F., 1915. On an Artesian Well at Oswaldkirk [in Corallian and Oxford 

Clay]. Proc. Yorks. Geol. Soc., N.S., vol. xix, pp. 284-5. 

LECKENBY, J., 1859. On the Kelloway Rock of the Yorkshire Coast. Q.J.G.S., 

vol. xv, pp. 4-15. 

LEEDS, E. T., 1908. On Metriorhynchus brachyrhynchus (Deslong.) from the Oxford 

Clay near Peterborough. Q.J.G.S., vol. lxiv, pp. 345-57. 

LYDEKKER, R., 1888. On the Skeleton of a Sauropterygian from the Oxford Clay near 

Bedford; Q.J.G.S., vol. xliv, pp. 89, 90; and on others: Geol. Mag. [3], vol. vt 

pp.350-6. 

, 1890. On a Crocodilian Jaw from Oxford Clay of Peterborough; and 

on Ornithosaurian Remains from the same. Q.J.G.S., vol. xlvi, pp. 284-8, 

429-31. 

• , 1893. On the Jaw of a New Carnivorous Dinosaur from [the Oxford Clay of] 

Peterborough. Q.J.G.S., vol. xlix, pp. 284-7. 

, 1899. Note on a Fossil Crocodile [Steneosaurus] from [the Oxford Clay of] 

Chickerell, Dorset. Proc. Dorset N.F.C., vol. xx, pp. 171-3. 

MANTELL, G. A., 1848. Observations on some Belemnites and other Fossil Remains 

of Cephalopoda, discovered by Mr. R. N. Mantell in the Oxford Clay near Trowbridge, 

Wiltshire. Phil. Trans. Roy. Soc., vol. cxxxviii B, pp. 171-83. 

MANTELL, R. N., 1850. An Account of the Strata and Organic Remains exposed in 

the Cuttings of the Branch Railway from the G.W. line near Chippenham, through 

Trowbridge to Westbury in Wiltshire. Q.J.G.S., vol. vi, pp. 310-15. 

MARCH, M. C., 1911. Studies in the Morphogenesis of Certain Pelecypoda: (3) The 

Ornament of Trigonia clavellata and some of its Derivatives. Mem. Manchester 

Lit. Phil. Soc., vol. Iv, no. 15, pp. 1-13. 

M'COY, F., 1848. On some new Mesozoic Radiata [from the Corallian]. Ann. Mag. 

Nat. Hist. [2], vol. ii, pp. 397-420. 

MORRIS, J., 1845. On the Occurrence of the Genus Pollicipes in the Oxford Clay [of 

Christian Malford]. Ann. Mag. Nat. Hist., vol. xv, pp. 30-1. 

, 1850. List of Organic Remains [and descriptions of new Oxford Clay and 

Kellaways Mollusca] obtained by R. N. Mantell, Esq., from the railway cuttings 

near Chippenham, through Trowbridge to Westbury, in Wiltshire. Q.J.G.S., 

vol. vi, pp. 315-19. 

NEAVERSON, E., 1925. The Zones of the Oxford Clay near Peterborough. P.G.A., 


NEWTON, E. T., 1878. Notes on a Crocodilian Jaw from the Corallian Rocks [Sandsfoot 

Grit] of Weymouth. Q.J.G.S., vol. xxxiv, pp. 398-400. 

, 1907. Note on Specimens of 'Rhaxella Chert* or 'Arngrove Stone' from Dartford 

Heath. P.G.A., vol. xx, p. 127. 

OWEN, R., 1844. A Description of certain Belemnites, preserved with a great proportion 

of their soft parts in the Oxford Clay at Christian Malford, W T ilts. Phil. Trans. 

Roy. Soc., vol. cxxxiv B, pp. 65-85. 

PRATT, S. P., 1841. Description of some New Species of Ammonites found in the 

Oxford Clay on the Line of the Great Western Railway, near Christian Malford. 

Ann. Mag. Nat. Hist., N.S., vol. viii, pp. 161-5. 

PRESTWICH, J., 1876. The Thickness of the Oxford Clay [at Oxford]. Geol. Mag. 

[2], vol. iii, pp. 237-9. 

PRINGLE, J., 1920. Wiltshire [Westbury Iron Ore]; in Lamplugh, Wedd and Pringle, 

Spec. Repts. Min. Resources Gt. Brit., vol. xii—Bedded Iron Ores, pp. 216-20. 


RICHARDSON, L., 1922. A Boring [in Oxford Clay and Kellaways Beds] at Calcutt, 

near Cricklade, Wiltshire. Geol. Mag., vol. lix, pp. 354-5. 

ROBERTS, T., 1889. The Upper Jurassic Clays of Lincolnshire. Q.J.G.S., vol. xlv, 

PP.545-6o. 

, 1892. The Jurassic Rocks of the Neighbourhood of Cambridge. Sedgwick 

Prize Essay for 1886, Cambridge. 

SALFELD, H., 1909. Die Beziehung zwischen Oxford Clay and Kellaway Beds (Rocks) 

Geol. Abt. Naturhistor. Gesellsch. Hannover, vol. ii, pp. 65-8. 

, 1914. t)ber einige stratigraphisch wichtige und einige seltene Arten der 

Gattung Perisphinctes aus dem oberen Jura Nordw ? estdeutschlands [P. antecedens


&c. figured]. Jahresbericht des Niedersachsischen geologischen Vereins zu 

Hannover (Geol. Abt. Naturhistor. Gesellsch. Hannover), 1914. 

SALFELD, H., 1917. Monographic der Gattung Ringsteadia (gen. now) Palaeontographica, 

vol. lxiii, pp. 69-84. 

SEELEY, H.G., 1861. Notice of the Elsworth and other New Rocks in the Oxford Clay, 

and of the Bluntisham Clay above them. The Geologist, vol. iv, pp. 460-1. 

, 1861. On the Fen Clay Formation. Ann. Mag. Nat. Hist. [3], vol. viii, 

PP- 503-4. 

, 1862. Notes on Cambridge Geology: 1. Preliminary Notice of the Elsworth 

Rock and Associated Strata. Ann. Mag. Nat. Hist. [3], vol. x, pp. 97-110. 

, 1874. On Murcenosaurus leedsii and on Opthalmosaiirus, from the Oxford Clay. 

Q.J.G.S., vol. xxx, pp. 197-208, 696-707. 

, 1875. On the Femur of Cryptosaurus eumerus Seeley, a Dinosaur from the 

Oxford Clay of Great Gransden. Q.J.G.S., vol. xxxi, pp. 149-51. 

, 1893. On Omosaurus phillipsi (Seeley) [from the Corallian near Slingsby, Yorks.]. 

Ann. Rept. Yorks. Phil. Soc. for 1892, pp. 52-7. 

SHEPPARD, G., 1913. The Kellaways Rock of South Cave, East Yorkshire. Naturalist, 

I9i3. PP- 359-6I. 

SHEPPARD, T., 1900. Notes on some Remains of Cryptocleidus from the Kellaways 

Rock of East Yorkshire. Geol. Mag. [4], vol. vii, pp. 535-8, and Trans. Hull. Geol. 

Soc., vol. v, pp. 23-4. 

, 1914. Teeth of Diplopodia versipora [from the Corallian of Seamer, Yorks.]. 


SHERBORN, C. D., 1888. Note on Webbina irregularis from the Oxford Clay of Weymouth. 

Proc. Bath N.H. and A.F.C., vol. vi, pp. 332-3 and plate. 

SORBY, H. C., 1851. On the Microscopical Structure of the Calcareous Grit of the 

Yorkshire Coast. Q.J.G.S., vol. vii, pp. 1-6. 

SPATH, L. F., 1926. Notes on Yorkshire Ammonites, no. x: On some Post-Liassic 

Ammonites and a New Species of Bonarellia [principally Kellaways Beds and Oxford 

Clay]. Naturalist, 1926, pp. 321-6. 

, 1929. Ammonites [Peltomorphites] williamsoni Phillips, and some Allied Forms 

[from the Yorkshire Corallian]. Naturalist, 1929, pp. 293-8. 

TEISSEYRE, L., 1889. Cber Proplanulites n. g. Neues Jahrb. fur Min., &c.,B.-B.vi, 

pp.148-76. 

TILL YARD, R. J., 1923. Tarsophlebiopsis mayi, a Dragon-fly, found in the Bodychamber 

of a Corallian Ammonite. Geol. Mag., vol. lx, pp. 146-52 and plate. 

TOMES, R. F., I 883. On some new or imperfectly known Madreporaria from the Coral 

Rag and Portland Oolite of the Counties of Wilts., Oxford, Cambridge, and York. 

Q.J.G.S., vol. xxxix, pp. 555-65. 

, 1900. Contributions to a History of the Mesozoic Corals of the County of York. 

Proc. Yorks. Geol. Soc., xiv, pp. 72-85. 

WALKER, J. F., 1888. On the Occurrence of Terebratula gesneri in [the Corallian of] 

Yorkshire. Ann. Rept. Yorks. Phil. Soc. for 1887, pp. 33-4, and plate. 

WEDD, C. B., 1898. On the Corallian Rocks of Upware, Cambridgeshire. Q.J.G.S., 

vol. liv, pp. 601-19. 

, 1901. On the Corallian Rocks of St. Ives (Huntingdonshire) and Elsworth. 

Q.J.G.S., vol. Ivii, pp. 73-85. 

WHITEAVES, J. F., 1861. On the Palaeontology of the Coralline Oolites of the Neighbourhood 

of Oxford. Ann. Mag. Nat. Hist. [3], vol. viii, pp. 142-7. 

WILSON, V., 1932. A Borehole Section in the Upper Jurassic [mainly Corallian] at 

Irton, near Scarborough. Trans. Leeds Geol. Assoc., vol. v, part 1, pp. 20-2. 

WOODWARD, A. S., 1897. On a New Specimen of the Mesozoic Ganoid Fish, Pholidophorus, 

from the Oxford Clay of Weymouth. Proc. Dorset F.C., vol. xviii, p. 150. 

WRIGHT, T., 1882-7. On a New Species of Brittle Star from the [Sandsfoot Grit] 

of Weymouth [Ophiurella nereida Wright]. 1882, Proc. Cots. N.F.C., vol. viii, 

PP- 53-5 ; and 1887, Geol. Mag. [3], vol. iv, pp. 97-8.

KIMERIDGE AND PORTLAND 655 

KIMERIDGE CLAY AND PORTLAND BEDS 

ANDREWS, C. W., 1921. On a New Chelonian [Tholemys passmorei] from the Kimmeridge 

Clay of Swindon. Ann. Mag. Nat. Hist. [9], vol. vii, pp. 145-53. 

ANDREWS, W. R., 1881. Outline of the Geology [Portland and Purbeck Beds] of the 

Vale of Wardour. Proc. Dorset N.F.C., vol. v, pp. 57-68. 

BAILEY, E. B., & WEIR, J., 1932. Submarine Faults as Boundaries of Facies [Kimeridgian 

Boulder Beds of Sutherland]. Rept. Brit. Assoc. for 1931 (London), 

PP.375-6. 

BATHER, F. A., 1911. Note on Crinoid Plates from the Penshurst Boring [Saccocoma 

from the Kimeridge Clay]. Sum. Prog. Geol. Surv. for 1910, pp. 78-9. 

, 1916. A Cidarid from the Hartwell Clay. Geol. Mag. [6], vol. iii, pp. 302-4. 

BLAKE, J. F., 1875. On the Kimmeridge Clay of England. Q.J.G.S., vol. xxxi* 

pp.196-237. 

, 1880. On the Portland Rocks of England. Q.J.G.S., vol. xxxvi, pp. 189-236. 

, 1880. The Portland Building Stone. Pop. Sci. Rev., N.S., vol. iv, pp. 205-12. 

, 1902. On a Remarkable Inlier in the [Kimeridgian] Rocks of Sutherland, and 

its Bearing on the Origin of the Breccia-Beds. [The 'Fallen Stack'.] Q.J.G.S., 

vol. lviii, pp. 290-312. 

BRODIE, P. B., 1853. Notice of the Occurrence of an Elytron of a Coleopterous Insect 

in the Kimmeridge Clay at Ringstead Bay, Dorset. Q.J.G.S., vol. ix, pp. 51-2. 

BRODIE, W. R., 1876 Notes on the Kimmeridge Clay of the Isle of Purbeck. P.G.A., 

vol. iv, pp. 517-18. 

BUCKMAN, S. S., 1922-6. Kimmeridge-Portland Chronology. T.A.,vol.iv, 1922-3, 

pp. 26-45; vol. vi, 1926, pp. 9-16, 24-40. 

CHATWIN, C. P., & PRINGLE, J., 1922. The Zones of the Kimmeridge and Portland 

Rocks at Swindon, Sum. Prog. Geol. Surv. for 1921, pp. 162-8. 

Cox, L. R., 1925. The Fauna of the Basal Shell-Bed of the Portland Stone, Isle of 

Portland. Proc. Dorset N.F.C., vol. xlvi, pp. 113-72. (See also Q.J.G.S., 1925, 

pp. cxxvii-viii.) 

, 1929-30. A Synopsis of the Lamellibranchia and Gastropoda of the Portland 

Beds of England. Proc. Dorset N.F.C., vol. 1, pp. 131-202. 

DANFORD, C. G., 1906. Notes on the Belemnites of the Speeton Clays. Trans. Hull 

Geol. Soc., vol. vi, part 1, pp. 1-14. 

, 1907. Notes on Speeton Ammonites. Proc. Yorks. Geol. Soc., vol. xvi, pp. 101- 

DAVIES, A. M., 1899. Contributions to the Geology of the Thame Valley [Kimeridge 

Clay, Portland and Purbeck Beds]. P.G.A., vol. xvi, pp. 15-58. 

DAVIES, W., 1876. On the . „ . large Reptile, Omosaurus armatus Owen, from the 

Kimmeridge Clay of Swindon, Wilts. Geol. Mag. [2], vol. iii, pp. 193-7. 

DOUVILLE, R., 1909. Sur VAmmonites mutabilis Sow. et sur les genres Proplanulites 

Teisseyre et Pictonia Bayle. Bull. Soc. geol. France [4], vol. ix, pp. 234-48. 

FITTON, W. H., 1836. Observations on some of the Strata between the Chalk and 

the Oxford Oolite in the South-East of England. Trans. Geol. Soc. [2], vol. iv, 

pp. 103-388. 

GODWIN-AUSTEN, R A. C., 1850. On the Age and Position of the Fossiliferous Sands 

and Gravels of Farringdon. QJ.G.S., vol. vi, pp. 454-78. [Includes descriptions 

of the Portland Beds of Swindon and Bourton.] 

GRAY, W., 1862. On the Geology of the Isle of Portland. P.G.A., vol. i, pp. 128-47. 

GRIFFITHS, J., 1921. Description of Portland Stone Quarries. The Quarry, 1921, 

pp 217-22. 

GROVES, T. B., 1887. The Abbotsbury Iron Deposits. Proc. Dorset N.F.C., vol. viii, 

pp.64-6. 

HUDLESTON, W. H., 1881. Note on some Gastropoda from the Portland Rocks of the 

Vale of Wardour and of Bucks. Geol. Mag. [2], vol. viii, pp. 385-95. 

, 1883. On the Geology of the Vale of Wardour. [Portland and Purbeck Beds.] 

P.G.A., vol. vii, pp. 161-85. 

HULKE, J. W., 1869-72, Notes on Saurians from Kimmeridge Bay. Q.J.G.S., 

vol. xxv, pp. 386-400, vol. xxvi, pp. 167-74, 611-22, vol. xxvii, pp. 440-3, 

vol. xxviii, pp. 34-5.


HULKE, J. W., 1880. Iguanodon Pre$twichiiy a New Species from the Kimeridge 

Clay ... at Cumnor. Q.J.G,S., vol. xxxvi, pp. 433-56 [and see Seeley, 1888, Rept. 

Brit. Assoc. for 1887, p. 698]. 

ILOVAISKY, D., 1923-4. Pavlovia, un nouveau genre d'Ammonites. Bull. Soc. des 

Naturalistes de Moscou, sect, geol., vol. ii (no. 4), pp. 329-60. 

JUDD, J. W., 1868. On the Speeton Clay. Q.J.G.S., vol. xxiv, pp. 250-5. 

KITCHIN, F. Iv., 1926. A new Genus of Lamellibranchs (.Hartzvellia, gen. nov.) from 

the Upper Kimmeridge Clay of England, with a Note on the Position of the Hartwell 

Clay. Ann. Mag. Nat. Hist. [9], vol. xviii, pp. 433-55. 

LAMPLUGH, G. W., 1896. On the Speeton Series in Yorkshire and Lincolnshire. 

Q.J.G.S., vol. Iii, pp. 179-220. 

, 1924. A Review of the Speeton Clays. Proc. Yorks. Geol. Soc., N.S., voL xx, 

pp. 1-31. 

LATTER, M. P., 1926. The Petrology of the Portland Sand of Dorset. P.G.A., 


MACGREGOR, M., 1916. A Jurassic Shore-line [in the Kimeridgian of Sutherland], 

Trans. Geol. Soc. Glasgow, vol. xvi, pp. 75-85. 

MANSEL-PLEYDELL, J. C., 1890. Memoir upon a New Ichthyopterygian from the 

Kimmeridge Clay of Gillingham, Dorset, Opthalmosaurus pleydelli. Proc. Dorset 

N.F.C., vol. xi, pp. 7-15. 

, 1892. Kimmeridge Coal-Money and other Manufactured Articles from the 

Kimmeridge Shale. Proc. Dorset N.F.C., vol. xiii, pp. 178-90. 

, 1894. Kimmeridge Shale. Proc. Dorset N.F.C., vol. xv, pp. 172-83. 

MASON, J. W., 1869. On Dakosaurus from the Kimmeridge Clay of Shotover Hill. 

Q.J.G.S., vol. xxv, pp. 218-20. 

MELMORE, S., 1931. Plesiosauridae from the Kimeridge Clay of Yorkshire Naturalist, 

1931, PP-337-8. 

MORRIS, J., 1849. On Neritomay a Fossil Genus of Gasteropodous Mollusks allied to 

Nerita [from the Portland Limestone of Swindon]. Q.J.G.S., vol. v, pp. 332-5. 

NEAVERSON, E., 1924. The Zonal Nomenclature of the Upper Kimmeridge Clay. 

Geol. Mag., vol. Ixi, pp. 145-51. 

, 1925. The Petrography of the Upper Kimmeridge Clay and Portland Sand 

in Dorset, Wiltshire, Oxfordshire and Buckinghamshire. P.G.A., vol. xxxvi, 

pp. 240-56. 

, 1925. Ammonites from the Upper Kimmeridge Clay. University Press, 

Liverpool. 

NEWTON, E. T., 1881. Notes on the Mandible of an Ischyodus townesendii found at 

Upwey, Dorset, in the Portland Oolite. P.G.A., vol. vii, pp. 116-19. 

OWEN, R., 1861-89. Monograph on the Reptilia of the Kimmeridge Clay and Portland 

Stone. Pal. Soc. 

PAVLOW, A., 1889. fitudes sur les couches jurass. et crEtacEes de la Russie: Jurassique 

sup. et cr£t. inf. de la Russie et d'Angleterre; et suppl. Bull. Soc. Nat. Moscou, 

N.S., vol. iii. 

, 1896. On the Classification of the Strata between the Kimeridgian and Aptian. 

Q.J.G.S., vol. Iii, pp. 542-55. 

PAVLOW, A., & LAMPLUGH, G. W., 1895. Argiles de Speeton et leurs Equivalents. 

Bull. Soc. Nat. Moscou, N.S., vol. v, p. 181. 

PHILLIPS, J., i860. Notice on some Sections of the Strata near Oxford. 2: Sections 

South of Oxford. Q.J.G.S., vol. xvi, pp. 307-11. 

PRESTWICH, J., 1879-80. Note on the Occurrence of a New Species of Iguanodon in 

a brickpit of the Kimeridge Clay at Cumnor Hurst, three miles W.S.W. of Oxford. 

Q.J.G.S., vol. xxxvi, pp. 430-2, and Geol. Mag. [2], vol. vi, pp. 193-5. 

PRINGLE, J., 1919. Palaeontological Notes on the Donnington Borehole [Lines.] of 

1917. [Kimeridge Clay.] Sum. Prog. Geol. Surv. for 1918, pp. 50-2. 

, 1920. Dorset [Abbotsbury Iron Ore]; in Lamplugh, Wedd and Pringle, Spec. 

Repts. Min. Resources Gt. Brit., vol. xii—Bedded Iron Ores, pp. 221-3. 

PRUVOST, P., 1925, Les subdivisions du Portlandian boulonnais d'apres les Ammonites. 

Ann. Soc. g6ol. du Nord, vol. xliv, pp. 187-215. 

RAISIN, C. A., 1903. The Formation of Chert and its Micro-Structures in some 

Jurassic Strata. P.G.A., vol. xviii, pp. 71-82.

KIMERIDGE AND PORTLAND 657 

SALFELD, H., 1915. Monographic der Gattung Cardioceras, Neumayr und Uhlig, Teil 1. 

Die Cardioceraten des oberen Oxford und Kimmeridge. Zeitschr. Deutsch. 

Geol. Gesell., vol. lxvii, pp. 149-204. 

SEELEY, H. G., 1871. On a New Species of Plesiosaurus from the Portland Limestone. 

Ann. Mag. Nat. Hist. [4], vol. viii, p. 181. 

, 1888. On Cumnoria, an Iguanodont Genus founded upon the Iguanodon prestwichi 

Hulke [from the Kimeridge Clay of Cumnor]. Rept. Brit. Assoc. for 1887, 

p. 698. 

SEWARD, A. C., 1911. The Jurassic [mainly Kimeridgian] Flora of Sutherland. 

Trans. Roy. Soc. Edinburgh, vol. xlvii, pp. 643-709. 

, 1912. A Petrified Williamsonia from [the Kimeridgian of Ethie], Scotland. 

Phil. Trans. Roy. Soc., vol. cciiiB, pp. 101-26. 

SEWARD, A. C., & BANCROFT, T. N., 1913. Jurassic [Kimeridgian] Plants from 

Cromarty and Sutherland, Scotland. Trans. Roy. Soc. Edin., vol. xlviii, pp. 867-88. 

SHEPPARD, T., 1902. Note on a Nearly Complete Specimen of Ichthyosaurus thyreospondylus 

from the Kimeridge Clay of Speeton. Geol. Mag. [4], vol. ix, p. 427, 

and Hull Museum Publications, no. 10, pp. 1-7. 

SPATH, L. F., 1924. On the Ammonites of the Speeton Clay and the Subdivisions of 

the Neocomian. Geol. Mag., vol. lxi, pp. 73-89. 

, 1925. Ammonites and Aptychi [Kimeridgian] from Somaliland [with a zonal 

table of the Kimeridgian and Portlandian]. Mon. Hunt. Mus. Glasgow, vol. i, 

part vii, pp. 111-64. 

STRAHAN, A., 1918. Kimmeridge Oil-Shale; Spec. Repts. Min. Resources Gt. Brit., 

vol. vii, ch. 2, pp. 24-40. Mem. Geol. Surv. 

WOODWARD, A. S., 1890. On a Head of Eurycormus from the Kimmeridge Clay of 

Ely. Geol. Mag. [3], vol. vii, pp. 289-92. 

, 1890. On a New Species of Pycnodont Fish (Mesodon damoni) from the Portland 

Oolite. Geol. Mag. [3], vol. vii, pp. 158-9. 

, 1892. On some Teeth of New Chimaeroid Fishes from the Oxford and Kimmeridge 

Clays of England. Ann. Mag. Nat. Hist. [6], vol. x, pp. 13-16 and 94-6. 

, 1895. Note on Megalosaurian Teeth discovered by Mr. J. Alstone in the 

Portlandian of Aylesbury. P.G.A., vol. xiv, pp. 31-2. 

, 1906. On a New Chimaeroid Fin-Spine from the Portland Stone. Proc. Dorset 

N.F.C., vol. xxvii, pp. 181-2 and plate. 

, 1906. On a Pycnodont Fish of the Genus Mesodon from the Portland Stone. 

Proc. Dorset N.F.C., vol. xxvii, pp. 183-7 and plate. 

WOODWARD, H., 1876. On some New Macrurous Crustacea from the Kimmeridge 

Clay of the Sub-Wealden Boring, Sussex. Q.J.G.S., vol. xxxii, pp. 47-50. 

WOODWARD, H. B., 1888. Note on the Portland Sands of Swindon and elsewhere. 


PURBECK BEDS 

ANDERSON, F. W., 1932. Phasal Deposition in the Middle Purbeck Beds of Dorset. 

Rept. Brit. Assoc. for 1931, pp. 379-80. 

ANDREWS, W. R., & JUKES-BROWNE, A. J., 1894. The Purbeck Beds of the Vale of 

Wardour. Q.J.G.S., vol. 1, pp. 44-69. 

BRODIE, P. B., 1839. A Notice on the Discovery of the Remains of Insects and a new 

genus of Isopodous Crustacea ... in the [Purbeck] Formation of the Vale of Wardour, 

Wilts. Proc. Geol. Soc., vol. iii, pp. 134-5. 

, 1847. Notice of the Existence of Purbeck Strata with Remains of Insects and 

other Fossils, at Swindon, Wilts. Q.J.G.S., vol. iii, pp. 53-4. 

, 1854. On the Insect Beds of the Purbeck Formation in Wilts, and Dorset. 

Q.J.G.S., vol. x, pp. 475-82. 

, 1867. On the Presence of the Purbeck Beds at Brill, in Buckinghamshire, &c. 

Q.J.G.S., vol. xxiii, pp. 197-9. 

CHAPMAN, F., 1896. Notes on the Microzoa from the Jurassic Beds [Kimeridge Clay 

and Purbeck Beds] at Hartwell. P.G.A., vol. xv, pp. 96-7. 

, 1900. Remarks upon the Ostracoda [chiefly Lower Purbeck forms from the 

Thame Valley]. P.G.A., vol. xvi, p. 58.


CHAPMAN, F., 1906. Note on an Ostracodal Limestone from Durlston Bay, Dorset. 

P.G.A., vol. xix, pp. 283-5. 

DAVIES, W., 1887. On New Species of Pholidophorus from the Purbeck Beds of Dorset. 

Geol. Mag. [3], vol. iv, pp. 337-9. 

ETHERIDGE, R., 1881. On a New Species of Trigonia from the Purbeck Beds of the Vale 

of Wardour. Q.J.G.S., vol. xxxvii, pp. 246-53. 

FALCONER, H., 1857. Description of two Species of the Fossil Mammalian Genus 

Plagiaulax from Purbeck. Q.J.G.S., vol. xiii, pp. 261-82. 

, 1862. On the Disputed Affinity of the Mammalian Genus Plagiaulax. Q.J.G.S., 

vol. xviii, pp. 348-69. 

FISHER, O., 1856. On the Purbeck Strata of Dorsetshire. Trans. Cambridge Phil. Soc., 

vol. ix, pp. 555-81. 

FITTON, W. H., 1835. Notice on the Junction of the Portland and Purbeck Strata on 

the Coast of Dorsetshire. Proc. Geol. Soc., vol. ii, pp. 185-7. 

FORBES, E., 1851. On the Succession of Strata and Distribution of Organic Remains 

in the Dorsetshire Purbecks. Rept. Brit. Assoc. for 1850, pp. 79-81, and Edinburgh 

Phil. Journ., vol. xlix, pp. 311-13, 391. 

HAWKINS, H. L., 1925. [Note on the finding of thirty-eight tests of Hemicidaris purbeckensis 

in Durlston Bay.] Q.J.G.S., vol. lxxxi, pp. cxxviii-ix. 

HULKE, J. W., 1878. Note on two Skulls from the Wealden and Purbeck Formations 

indicating a new Sub-group of Crocodilia. Q.J.G.S., vol. xxxiv, pp. 377-82. 

JONES, T. R., 1878. Notes on some Fossil Bivalved Entomostraca: iv [Purbeck and 

Wealden Ostracoda]. Geol. Mag. [2], vol. v, pp. 103-10, 277-8. 

, 1885. On the Ostracoda of the Purbeck Formation. Q.J.G.S., vol. xii, pp. 311- 

53- 

, 1890. On some Fossil Estherice: B. Purbeck Estherice. Geol. Mag. [3], vol. vii, 

PP- 385-90. 

KOERT, W., 1898. Geol. u. pal. Untersuch. der Grenzschichten zwischen Jura u. 

Kreide auf der Sudwestseite des Selter. [Successful application of the Ostracod 

zones to the N.W. German Purbecks and comparison with England, with list of 

fossils common to the two.] Inaug.-Dissert. Gottingen, pp. 1-57. 

LYDEKKER, R., 1889. On Certain Chelonian Remains from the Wealden and Purbeck. 

Q.J.G.S., vol. xlv, pp. 511-18. 

LYDEKKER, R., & BOULENGER, G. A., 1887. Notes on Chelonia from the Purbeck, 

Wealden and London Clay. Geol. Mag. [3], vol. iv, pp. 270-5. 

MAILLARD, G., 1884. Invertebres du Purbeckien du Jura. [Descriptions of many 

English Purbeck fossils and detailed comparisons of the strata.] Mem. Soc. pal. 

Suisse, vol. xi. 

MANSEL-PLEYDELL, J. C., 1885. A Fossil Chelonian Reptile [Pleurosternon ovatum 

Owen] from the Middle Purbecks. Proc. Dorset N.F.C., vol. vi, pp. 66-9 and plate. 

, 1896. On the Footprints of a Dinosaur (.Iguanodon ?) from the Purbeck Beds of 

Swanage. Proc. Dorset N.F.C., vol. xvii, p. 115. 

MERRETT, E. A., 1924. Ostracoda found in the Purbeck Beds of the Vale of Aylesbury 

(Fossil Ostracoda in Stratigraphy). Geol. Mag., vol. Ixi, pp. 233-8. 

OWEN, R., 1854. On some Fossil Reptilian and Mammalian Remains from the 

Purbecks. Q.J.G.S., vol. x, pp. 420-33. 

, 1879. On the Association of Dwarf Crocodiles with the Diminutive Mammals 

of the Purbeck Shales. Q.J.G.S., vol. xxxv, pp. 148-55. 

PHILLIPS, J., 1858. On the Estuary Sands in the Upper Part of Shotover Hill. Q.J.G.S., 

vol. xiv, pp. 236-41. 

SEELEY, H. G., 1869. Note on the Pterodactylus macrurus (Seeley) a New Species from 

the Purbeck Limestone. . . . Proc. Camb. Phil. Soc., parts vii-x, p. 130. 

, 1875. On an Ornithosaurian (Doratorhynchus validus) from the Purbeck Limestone 

of Langton, near Swanage. Q.J.G.S., vol. xxxi, pp. 465-8. 

, 1893. On a Reptilian Tooth with two Roots [Nuthetes, from the Purbeck Beds]. 

Ann. Mag. Nat. Hist. [6], vol. xii, pp. 227-30, 274-6. 

SEWARD, A. C., 1897. On Cycadeoidea gigantea, a New Cycadean Stem from the Purbeck 

Beds of Portland. Q.J.G.S., vol. liii, pp. 22-39. 

WEBSTER, T., 1826. Observations on the Purbeck and Portland Beds. Trans. Geol. 

Soc. [2], vol. ii, pp. 37-44.

PURBECK BEDS 659 

WESTON, C. H., 1852. On the Sub-escarpments of the Ridgway Range, and their 

Contemporaneous Deposits in the Isle of Portland. Q.J.G.S., vol. viii, pp. 

110-20. 

WESTWOOD, J. O., 1854. Fossil Insects from the Middle and Lower Purbeck Beds of 

Dorset; in 'Contributions to Fossil Entomology'. Q.J.G.S., vol. x, pp. 382-96. 

WETHERED, E., 1892. On the Occurrence of Fossil Forms of the Genus Chara in the 

Middle Purbeck Strata of Lulworth, Dorset. Proc. Cots. N.F.C., vol. x, pp. 101-4. 

W T ILLETT, H., & E. W., 1881. Notes on a Mammalian Jaw from the Purbeck Beds at 

Swanage, Dorset. Q.J.G.S., vol. xxxvii, pp. 376-80. 

W OOD, S. V., 1863. On the Events which produced and terminated the Purbeck and 

Wealden Deposits of England and France, and on the Geographical Conditions of 

the Basin in which they were accumulated. Phil. Mag. [4], vol. xxv, pp. 268-89. 

WOODWARD, A. S., 1890. On some New Fishes from the English Wealden and Purbeck 

Beds, referable to the Genera Oligopleurus, Strobilodus and Mesodon. Proc. 

Zool. Soc., pp. 346753- 

, 1895. A Contribution to Knowledge of the Fossil Fish Fauna of the English 

Purbeck Beds. Geol. Mag. [4], vol. ii, pp. 145-52, 401-2. 

, 1909. Note on a Chelonian Skull from the Purbeck Beds of Swanage. Proc. 

Dorset N.F.C., vol. xxx, pp. 143-4, an d plate. 

, 1912. Notes on a Maxilla of Triconodon from the Middle Purbeck Beds of 

Swanage. P.G.A., vol. xxiii, pp. 100-1 and plate. 

, 1916-19. The Fossil Fishes of the English Wealden and Purbeck Formations. 

Pal. Soc. 

YOUNG, J. T., 1878. On the Occurrence of a Freshwater Sponge in the Purbeck Limestone. 


EXCURSIONS OF THE GEOLOGISTS' ASSOCIATION 

in the course of which Jurassic rocks were studied; arranged geographically. 

Those especially important marked *. 

Isle of Purbeck: Portland-Purbeck Beds, HUDLESTON, W. H., 1882, vol. vii, 

PP> 377-90. 

*Swanage, Corfe Castle, Kimeridge, &c. Kimeridge Clay—Purbeck Beds, HUDLES- 

TON, W. H., MANSEL, O. L., and MONCKTON, H. W., 1896, vol. xiv, pp. 307-24. 

* Swanage and Lulworth Cove. Kimeridge Clay-Purbeck Beds, HOVENDEN, F., 

MONCKTON, H. W., and WOODWARD, A. S., 1910, vol. xxi, pp. 510-21. 

Weymouth. Oxford Clay-Purbeck Beds, HUDLESTON, W. H., 1889, vol. xi, pp. xlixlvii. 

Weymouth and Portland: Corallian-Portlandian, BLAKE, J. F., and HUDLESTON, 

W. H., 1879, vol. vi, pp. 172-4. 

Bridport and Weymouth: Middle Lias-Portland Beds, BLAKE, J. F., HUDLESTON, 

W. H., BUCKMAN, S. S., and MONCKTON, H. W., 1898, vol. xv, pp. 293-304. 

Bridport, Bothenhampton, Burton Bradstock and Eype: Middle Lias-Forest Marble, 

WOODWARD, H. B., 1885, vol. ix, pp. 200-9. 

*Sherbome and Bridport: Upper Lias-Inferior Oolite, HUDLESTON, W. H., 1885, 

vol. ix, pp. 187-99. 

*Bridport, Beaminster and Crewkerne: Upper Lias-Inferior Oolite, RICHARDSON, L., 

1915, vol. xxvi, pp. 47-78. 

Lyme Regis: Rhaetics-Upper Lias, WOODWARD, H. B., 1889, vol. xi, pp. xxvi-xlix. 

Lyme Regis: Rhaetic Beds and Lower Lias, WOODWARD, H. B., 1906, vol. xix, 

pp.320-40. 

*Charmouth and Lyme Regis: Lower and Middle Lias, LANG, W. D., 1915, vol. xxvi, 

pp. 111-18. 

West Somerset and North Devon: Rhaetics at Watchet, HERRIES, R. S., 1896, 

vol. xiv, pp. 433-40. 

*West Somerset: Rhaetics and Lower Lias of Minehead coast, RICHARDSON, L., 1914, 

vol. xxv, pp. 97-102. 

Yeovil District: Middle Lias to Inferior Oolite, LOBLEY, J. L., 1871, vol. ii, 

PP- 247-50.

66o BIBLIOGRAPHY 

*Dunball, Burlescombe, Ilminster, Chard, Ham Hill and Bradford Abbas; Rhaetic 

Beds-Fuller's Earth, RICHARDSON, L., USSHER, W. A. E., and others, 1911, 

vol. xxii, pp. 246-63. 

# Frome District, Somerset: Lower Lias-Fuller's Earth, RICHARDSON, L., 1909, 

vol. xxi, pp. 209-28. 

Dundry Hill: Lower Lias-Inferior Oolite, WILSON, E., 1893, v °h x iii> PP- 128-32. 

Dundry Hill: Lower Lias-Inferior Oolite, BUCKMAN, S. S., 1901, vol. xvii 

pp.152-8. 

Bristol District: Rhaetics and Lower Lias of Radstock, TUTCHER, J. W., 1919, 

vol. xxx, pp. 116-18. 

Aust Cliff: Rhaetic Beds, WINWOOD, H. H., 1901, vol. xvii, pp. 163-6. 

Bath: Rhaetic-Upper Lias, WINWOOD, H. H., 1872, vol. iii, pp. 89-92. 

Bath: General, MOORE, C., 1879, vol. vi, pp. 196-201. 

Bath and Midford: Inferior Oolite-Fuller's Earth, WOODWARD, H. B., 1893, 

vol. xiii, pp. 125-8. 

*Bradford-on-Avon: Great Oolite-Forest Marble, WINWOOD, H. H., and WICKES, 

W. H., 1893, V °K X I"> PP- I 3 2 "7- 

*Chippenham, Calne, Kellaways and Corsham: Great Oolite-Corallian, WOODWARD, 

H. B., and WINWOOD, H. H., 1896, vol. xiv, pp. 339~54- 

Westbury, Wilts.: Corallian and Kimeridge Clay, WOODWARD, H. B., 1893, vol. xiii, 

pp. 137-40. 

Mere and Maiden Bradley in Wiltshire: Corallian of the Vale of Wardour, BARTLETT, 

B. POPE, 1916, vol. xxvii, pp. 127-32. 

Salisbury, Stonehenge and Vale of Wardour: Portland-Purbeck, HUDLESTON, W. H., 

1881, vol. vii, pp. 134-42. 

Teffont Evias, Chilmark and Tisbury (Vale of Wardour): Portland-Purbeck Beds, 

ANDREWS, W. R., 1903, vol. xviii, pp. 149-58. 

New G.W.R. Line from Wootton Bassett to Filton: Rhaetics-Oxford Clay, WIN- 

WOOD, H. H., 1901, vol. xvii, pp. 144-50. 

*Mid and South Cotswolds: Lower Lias-Inferior Oolite, RICHARDSON, L., 1908, 

vol. xx, pp. 514-29. 

Cheltenham District: Rhaetic (also Inferior Oolite mentioned), LOBLEY, J. L., 1874, 

vol. iv, pp. 167-74. 

Cheltenham and Stroud: Lower Lias-Inferior Oolite, BUCKMAN, S. S., 1897, vol. xv, 

pp. 175-82. 

*Vale of Evesham and the North Cotswolds: Lower Lias-Inferior Oolite, RICHARD- 

SON, L., 1904, vol. xviii, pp. 391-408. 

Cirencester and Minchinhampton: Middle Lias-Kellaways Beds, HARKER, A., 1888, 

vol. x, pp. 157-63. 

Cirencester and District: Great Oolite, RICHARDSON, L., 1925, vol. xxxvi, pp. 80-92. 

Swindon: Portland Beds, BLAKE, J. F., 1892, vol. xii, pp. 326-7. 

*Swindon: Kimeridge Clay and Portland Beds, GORE, C. H., CHATWIN, C. P., and 

PRINGLE, J., 1922, vol. xxxiii, pp. 152-5. 

Swindon and the Vale of White Horse: Corallian-Portland Beds, HAWKINS, H. L., 

and PRINGLE, J., 1923, vol. xxxiv, pp. 233-41. 

*Swindon and Faringdon: Kimeridge Clay-Purbeck Beds, HUDLESTON, W. H., 1876, 

vol. iv, pp. 543-54- 

Faringdon: Corallian, TREACHER, L., 1907, vol. xx, pp. 115-21. 

Faringdon, [Marcham] and Abingdon: Corallian, HINDE, G. J., and WOODWARD, 

H. B., 1892, vol. xii, pp. 327-33. 

Culham and Abingdon: Corallian-Kimeridge Clay, TREACHER, L., 1908, vol. xx, 

PP- 548-52. 

Culham and Wallingford: Kimeridge Clay, WHITE, H. J. O., 1903, vol. xviii, 

pp. 300-6. 

Corallian Rocks South-West of Oxford: Corallian, ARKELL, W. J., 1931, vol. xlii, 

PP- 50-2. 

Oxford: Corallian-Kimeridge Clay, BADCOCK, P., 1862, vol. i, pp. 155-7. 

Oxford: Middle Lias-Portland, HUDLESTON, W. H., and PARKER, J., 1874, v °h i y > 

PP. 9i-7. 

*Oxford: Corallian, HUDLESTON, W. H., 1880, vol. vi, pp. 338-44.

EXCURSION REPORTS 661 

Oxford District: Middle Lias-Portland Beds, PRINGLE, J., 1926, vol. xxxvii, 

PP. 447-58. 

Headington, Shotover and Wheatley: Corallian-Portland Beds, BLAKE, J. F., 1902, 

vol. xvii, pp. 383-5. 

Wheatley and Arngrove: Oxford Clay, Corallian and Ampthill Clay, DAVIES, A. M., 

1909, vol. xxi, pp. 234-6. 

•Dorton, Brill and Arngrove: Oxford, Ampthill and Kimeridge Clays, DAVIES, A. M., 

1907, vol. xx, pp. 183-6. 

Brill [and Blackthorn Hill]: Forest Marble-Purbeck Beds, BLAKE, J. F., 1893, 


Ashendon and Dorton Railway Cuttings: Oxford and Ampthill Clays, DAVIES, A. M., 

1909, vol. xxi, pp. 394-5- 

New Railway from Bicester to Aynho: Inferior Oolite-Cornbrash, BARROW, G., 

1908, vol. xxi, pp. 36-45. 

Thame District: Portland-Purbeck, DAVIES, A. M., 1899, vol. xvi, pp. 157-9. 

Aylesbury: Kimeridge Clay-Purbeck Beds, MORRIS, J., 1873, vol. iii, pp. 210-11. 

* Aylesbury: Kimeridge Clay-Purbeck Beds, HUDLESTON, W. H., 1880, vol. vi, 

PP- 344-52. 

Aylesbury: Kimeridge Clay-Purbeck Beds, HUDLESTON, W. H., 1888, vol. x, 

pp.166-72. 

Aylesbury, Hartwell and Stone: Kimeridge Clay-Purbeck Beds, DAVIES, A. M., and 

EMARY, P., 1897, vol. xv, pp. 90-4. 

Aylesbury, Hartwell and Stone: Kimeridge Clay and Portland Beds, DAVIES, A. M., 

1912, vol. xxiii, pp. 254-7. 

Whitchurch, Oving and Quainton: Oxford Clay-Purbeck Beds, DAVIES, A. M., 1897, 

vol. xv, pp. 207-9. 

Bedford and Clapham: Cornbrash-Oxford Clay, CAMERON, A. C. G., 1889, vol. x, 

pp. 504-10. 

Bedford: Great Oolite-Kellaways Beds, WOODWARD, H. B., 1905, vol. xix, pp. 142-6. 

Cambridge and Ely: Kimeridge Clay, MARR, J. E., and LEIGHTON, T., 1894, 


•Peterborough: Oxford Clay (with list and bibliography of Oxford Clay Vertebrata 

in the Leeds collection), LEEDS, A. N., and WOODWARD, A. S., 1897, vol. xv, 

pp. 188-93. 

Oxford University Museum, Enslow Bridge, Kirtlington and Woodstock: Great 

Oolite, ALLORGE, M. M., and BAYZAND, C. J., 1910, vol. xxii, pp. 1-5. 

Oxford, Stonesfield and Fawler: Middle Lias-Oxford Clay, BAYZAND, C. J., 1908, 

vol. xxi, pp. 25-9. 

* Chipping Norton: Lower Lias to Great Oolite, HUDLESTON, W. H., 1878, vol. v, 

pp.378-89. 

•Banbury: Middle Lias-Great Oolite, BEESLEY, T., 1873, vol. iii, pp. 197-204. 

Banbury: Middle Lias-Great Oolite, WALFORD, E. A., 1914, vol. xxv, pp. 71-7. 

Banbury, Bloxham, Edge Hill and Hook Norton: Middle Lias-Inferior Oolite, 

WALFORD, E. A., 1895, vol. xiv, pp. 177-85. 

•Banbury and Towcester Districts: Upper Lias-Great Oolite, RICHARDSON, L., 1921, 

vol. xxxii, pp. 109-22. 

•Northants: Marlstone-Cornbrash (especially Great Oolite): THOMPSON, B., and 

CRICK, W. D., 1891, vol. xii, pp. 172-90. 

•Northamptonshire: Upper Lias-Great Oolite, THOMPSON, B., 1921, vol. xxxii, 

pp. 219-26. 

•New Railway at Catesby, Northants: Lower-Upper Lias, THOMPSON, B., 1896, 

vol. xiv, pp. 421-30. 

Kettering and Thrapston: (Brief general remarks), BLAKE, J. F., and THOMPSON, B., 

1900, vol. xvi, pp. 516-17. 

•Wellingborough: Upper Lias-Great Oolite, THOMPSON, B., and CRICK, W. D., 1894, 

vol. xiii, pp. 283-91. 

Stamford, Collyweston and Ketton: Inferior Oolite, THOMPSON, B., 1906, vol. xix, 

pp.367-70. 

Weldon, Dene and Gretton: Inferior Oolite, THOMPSON, B., 1899, vol. xvi, 

pp. 226-31.

66z BIBLIOGRAPHY 

Leicestershire: Lower Lias-Lincolnshire Limestone, HARRISON, W. J., 1877, vol. v, 

pp. 142-6. 

Nottingham District: The Vale of Belvoir: Rhaetics-Upper Lias, SWINNERTON, 

H. H., 1914, vol. xxv, pp. 84-5. 

Mid-Lincolnshire: Middle Lias-Inferior Oolite, also Kimeridge Clay, PRESTON, H., 

KENDALL, P. F., and CARTER, W. L., 1905, vol. xix, pp. 114-30. 

Lincoln: Lower, Middle and Upper Lias, CARR, W. D., 1884, vol. viii, pp. 383-5. 

Lincoln: Middle and Upper Lias and Kimeridge Clay, DALTON, W. H., and others, 

1885, vol. viii, pp. 383-9. 

East Coast of Yorkshire: General, BLAKE, J. F., and others, 1891, vol. xii, pp. 207-22. 

Yorkshire Coast: Lower, Middle and Upper Lias (higher beds briefly mentioned), 

HERRIES, R. S., 1906, vol. xix, pp. 464-77. 

*East Sutherland: Lower Lias-Kimeridgian, MACGREGOR, M., READ, H. H., MANSON, 

W., and PRINGLE, J., 1930, vol. xii, pp. 63-86. 

P A L A E O N T O L O G Y 

Some palaeontological works not classifiable in the stratigraphical section. 

[Note.—This selection is added for the sake of usefulness and not with any idea of completeness.] 

VERTEBRATA 

WOODWARD, A. S., & SHERBORN, C. D., 1890. A Catalogue of British Fossil Vertebrata. 

London. 

MAMMALIA 

LYDEKKER, R., 1885-7. Catalogue of the Fossil Mammalia in the British Museum. 

5 parts. London. 

OSBORN, H. F., 1888. On the Structure and Classification of the Mesozoic Mammalia. 

Journ. Acad. Nat. Sci. Philad., vol. ix, p. 282. 

OWEN, R., 1871. Monograph of the Fossil Mammalia of the Mesozoic Formations. 

Pal. Soc. 

SIMPSON, G. G., 1928. A Catalogue [Monograph] of the Mesozoic Mammalia in the 

Geological Dept. of the British Museum. 

REPTILIA AND AMPHIBIA 

BOULENGER, G. A., 1891. On British Remains of Homceosaurus, with Remarks on the 

Classification of the Rhynchocephalia. Proc. Zool. Soc., pp. 167-72. 

LYDEKKER, R., 1888. Note on the Classification of the Ichthyopterygia, with a Notice 

of Two New Species, Geol. Mag. [3], vol. v, pp. 309-14. 

, 1888-90. Catalogue of the Fossil Reptilia and Amphibia in the British Museum. 

8vo. London. 

, 1889. On the Remains and Affinities of five Genera of Mesozoic Reptiles. 

Q.J.G.S., vol. xlv, pp. 41-58. 

, 1890. Contributions to our Knowledge of the Dinosaurs of the Wealden 

and the Sauropterygians of the Purbeck and Oxford Clay. Q.J.G.S., vol. xlvi, 

PP-37-53. 

, 1904. Vertebrate Palaeontology of Cambridgeshire; In Marr and Shipley's 

Handbook to the Natural History of Cambridgeshire. Pp. 51-70. Cambridge. 

MANSEL-PLEYDELL, J. C., 1888. Fossil Reptiles of Dorset. Proc. Dorset N.F.C., 

vol. ix, pp. 1-40. 

NEWTON, E. T., 1888. Notes on Pterodactyls. P.G.A., vol. x, pp. 406-24. 

OWEN, R., 1849-84. British Fossil Reptiles. London. 

, 1861-81. A Monograph of the Fossil Reptilia of the Liassic Formations. 

Pal. Soc. 

, 1874-89. A Monograph on the Fossil Reptilia of the Mesozoic Formations. 

Pal. Soc. 

SEELEY, H. G., 1869. Index to the Fossil Remains of Aves, Ornithosauria and Reptilia 

from the Secondary System of Strata, arranged in the Woodwardian Museum at 

Cambridge. Cambridge.

PALAEONTOLOGY 663 

WOODWARD, A. S., 1885. On the Literature and Nomenclature of British Fossil 

Crocodilia. Geol. Mag. [3], vol. ii, pp. 496-510. 

, 1886. The History of Fossil Crocodiles. P.G.A., vol. ix, pp. 288-344. 

PISCES 

WOODWARD, A. S., 1886. On the Palaeontology of the Selachian Genus Notidanus. 

Geol. Mag. [3], vol. iii, pp. 205-17, 253-9. 

,1889-1901. Catalogue of Fossil Fishes in the British Museum. Parts i-iv. 

[With full bibliography.] London. 

, 1890. On the Palaeontology of the Sturgeons. P.G.A., vol. xi, pp. 24-44; and 

The Fossil Sturgeon of the Whitby Lias. Naturalist, 1890, pp. 101-7. 

, 1890-2. A Synopsis of the Fossil Fishes of the English Lower Oolites, and 

Supplementary Observations; P.G.A., vol. xi, pp. 285-306, and vol. xii, pp. 238-41. 

, 1893. On some British Upper Jurassic Fish-remains, of the genera Caturus, 

Gyrodus and Notidanus [Oxford Clay, Corallian and Portland Stone]. Ann. Mag. 

Nat. Hist. [6], vol. xii, pp. 398-462. 

, 1906. The Study of Fossil Fishes. P.G.A., vol. xix, pp. 266-82. 

INVERTEBRATA 

ARTHROPODA 

CRUSTACEA 

DARWIN, C., 1851. A Monograph on the Fossil Lepadidae or Pedunculated Cirripedes 

of Great Britain. Pal. Soc. 

JONES, T. R., 1862. A Monograph of the Fossil Estheriae [Phyllopoda]. Pal. Soc. 

, 1884. Notes on the Foraminifera and Ostracoda from the Deep Boring at 

Richmond. Q.J.G.S., vol. xl, pp. 765-83. 

MERRETT, E. A., 1924. Fossil Ostracoda and their use in Stratigraphical Research. 

Geol. Mag., vol. lxi, pp. 228-38. 

WITHERS, T. H., 1929. Catalogue of the Fossil Cirripedia in the Dept. of Geology; 

vol. i, Triassic and Jurassic. Brit. Mus. Cat. [with full bibliography]. 

WOODS, H., 1925-31. A Monograph of the Fossil Macrurous Crustacea of England. 

Pal. Soc. [with full bibliography]. 

WOODWARD, H., 1868. Contributions to British Fossil Crustacea. Geol. Mag., vol. v, 

PP.353-7. 

, 1877. A Catalogue of British Fossil Crustacea. London. 

INSECTA 

BRODIE, P. B., 1845. A History of the Fossil Insects in the Secondary Rocks of 

England. London. 

, 1874-5. On the Correlation of Fossil Insects. Proc. Warwicks. N.F.C. for 

1873, pp. 12-28, and for 1874, pp. 16-38. 

COCKERELL, T. D. A., 1915. British Fossil Insects. Proc. U.S. Nat. Mus., vol. xlix 

(1916), pp. 469-99. [Some of Brodie's material re-described and figured.] 

Goss, H., 1878. The Insect Fauna of the Mesozoic Period. P.G.A., vol. vi, pp. 116-50. 

HANDLIRSCH, A., 1906-8. Die Fossilen Insecten und die Phylogenie der Rezenten 

Formen. Leipzig. Jurassic, vol. i, pp. 411-660. [A complete inventory and 

revision.] 

TILLYARD, R. J., 1925. Fossil Insects, No. i: The British Liassic Dragon-flies 

(Odonata). Brit. Mus. Nat. Hist., London. 

, 1930. The Evolution of the Class Insecta. Papers and Proc. Royal Soc. 

Tasmania, 1930; and Nature, vol. cxxvi, pp. 996-8. 

WESTWOOD, J. O., 1854. Contributions to Fossil Entomology. Q.J.G.S., vol. x, 

PP. 378-96. [First descriptions and figures of many insects from the Purbecks, 

Stonesfield Slate, Lias and Wealden; revised in Handlirsch, above.]

664 

BIBLIOGRAPHY 

MOLLUSCA 

LAMELLIBRANCHIA 

AGASSIZ, L., 1841-5. Etudes critiques sur les Mollusques fossiles: (1) Memoire sur 

les Trigonies, 1841; (2) Monographie des Myes, 1842-5. 

ALLEN, H. A., 1905-6. Catalogue of Types and Figured Specimens of British Lamellibranchiata 

from the Rhaetic Beds, Lias, Lower, Middle and Upper Oolites, preserved 

in the Museum of Practical Geology, London. Summ. Prog. Geol. Surv. for 1904, 

pp. 172-7, and for 1905, pp. I75~95« 

ARKELL, W. J., 1930. The Generic Position of Phylogeny of some Jurassic Arcidae. 

Geol. Mag., vol. lxvii, pp. 297-310 and pp. 337-52. 

, 1931. Berichtigungen der Identitat gewisser jurassischer Pecten-Arten. 

Centralblatt fur Min., &c., Abt. B., pp. 430-43. 

BIGOT, A., 1893-4. Contributions a Tetude de la faune jurassique de Normandie: 

(1) Memoire sur les Trigonies. (2) Memoire sur les Opis. Mem. Soc. Linn. 

Normandie, vols, xvii and xviii. 

Cox, L. R., 1929. Notes on the Mesozoic Family Tancrediidae, with Descriptions of 

several British Upper Jurassic Species, and of a New Genus, Eodonax. Ann. Mag. 

Nat. Hist. [10], vol. iii, pp. 569-94. 

DEECKE, W., 1925. Fossilium Catalogus. 1. Animalia; Pars 30. Trigoniidae Mesozoicae 

(Myophoria exclusa). 

EUDES-DESLONGCHAMPS, J. A., 1858. Essai sur les Plicatules fossiles des terrains de 

Calvados. Mem. Soc. Linn. Normandie, vol. vi, p. 220. 

GERBER, E., 1918. Beitrage zur Kenntnis der Gattungen Ceromya und Ceromyopsis. 

MEm. Soc. pal. Suisse, vol. xliii. 

GUILLAUME, L., 1927. Revision des Posidonomyes jurassiques. Bull. Soc. g6ol. France 

[4], vol. xxvii, pp. 217-34. 

JOURDY, E., 1924. Histoire naturelle des Exogyres. Ann. Paleont., vol. xiii, pp. 1-104. 

LYCETT, J., 1872-83. A Monograph of the British Fossil Trigonice. Pal. Soc. 

MANSEL-PLEYDELL, J. C., 1879. On the Dorset Trigonice. Proc. Dorset N.F.C., 

vol. iii, pp. 111-34. 

MEEK, F. B., 1864. Remarks on the Family Pteriidae (= Aviculidae) with Description 

of some New Fossil Genera. Amer. Journ. Sci., vol. xxxvii, pp. 212-20. 

MOESCH, C., 1875. Monographie der Pholadomyen. MEm. Soc. pal. Suisse, vol. 1. 

PFANNENSTIEL, M., 1928. Organisation und Entwicklung der Gryphaen. Palaeobiologica, 

vol. i, pp. 381-418. 

PHILIPPI, E., 1898-1900. Morphologie und Phylogenie der Lamellibranchier; 

Pectinidae and Limidae. Zeitschr. Deutsch. Geol. Gesell., vol. 1, p. 596, vol. Iii, 

pp. 64, 619. 

ROLLIER, L., 191 I. Les Facias du Dogger ou Oolithique dans le Jura et les regions 

voisines. Mem. public par la fondation Schuyder von Wartensee k Zurich. 

, 1912-17. Fossiles nouveaux ou peu connus des terrains secondaires du Jura 

et des contrees environnantes. M£m. Soc. pal. Suisse, vols, xxxviii-xlii. [Catalogues 

and lists of species ranged according to horizons, with many new names; also 

Echinoderma, Serpulae and Brachiopoda in vol. xxxvii, 1911.] 

SCHAFLE, L., 1929. Ober Lias und Doggeraustern. Geol. u. Pal. Abhandlungen, 

Jena, vol. xxi (N.F., vol. xvii), Heft 2, pp. 65-150. 

STOLICZKA, A., 1871. The Pelecypoda, with a Review of all Known Genera of this 

Class, Fossil and Recent. Palaeontologia Indica; Mem. Geol. Surv. India. 

WALFORD, E. A., 1885. On the Stratigraphical Position of the Trigonice of the Lower 

and Middle Jurassic Beds of North Oxfordshire and Adjacent Districts. Q.J.G.S., 

vol. xii, pp. 35-47. 

GASTROPODA 

ALLEN, H. A., 1903-4. Catalogue of Types and Figured Specimens of British Gastropoda 

from the Rhaetic Beds, Lias and Lower, Middle and Upper Oolites, preserved 

in the Museum of Practical Geology, London. Summ. Prog. Geol. Surv. for 1902, 

pp. 217-28, and for 1903, pp. 175-87. 

COSSMANN, M., 1895-1913. Contributions & la palEontologie fran9aise des terrains


jurassiques: Etudes sur les Gastropodes des terrains jurassiques. Mem. Soc. geol. 

France, vols, v, viii, xix. 

COSSMANN, M., 1895-1921. Essais de Paleoconchologie comparee. Livr. i-xii. 

HUDLESTON, W. H., & WILSON, E., 1892. A Catalogue of British Jurassic Gasteropoda. 

London, Dulau. 

CEPHALOPODA 

AMMONOIDEA 

BLAKE, J. F., 1892-3. The Evolution and Classification of the Cephalopoda. P.G.A., 

vol. xii, pp. 275-95, and vol. xiii, pp. 24-39. 

BUCKMAN, S. S., 1909-30. Type Ammonites [and Yorkshire Type Ammonites]. 

Vols, i-vii. Indices by A. Morley Davies, 1930. 

BUCKMAN, S. S., & BATHER, F. A., 1894. Can the Sexes in Ammonites be Distinguished? 

Nat. Science, vol. iv, pp. 427-32. 

CRICK, G. C., 1898. List of Types and Figured Specimens of Fossil Cephalopoda in 

the British Museum (Natural History). B.M., London. 

HYATT, A., 1889. The Genesis of the Arietidae. Smithsonian Contrib. Knowl., 1889. 

LANG, W. D., 1919. The Evolution of Ammonites. P.G.A., vol. xxx, pp. 49-65. 

SCHINDEWOLF, O. H., 1925. Entwurf einer Systematik der Perisphincten. Neues 

Jahrb. fur Min., &c., B.-B. liiB, pp. 309-43. 

, 1926. Zur Systematik der Perisphincten. Neues Jahrb. fiir Min., &c., B.-B., 

IVB, pp. 497-517. 

SCHWARZ, E. H. L., 1894. The Aptychus. Geol. Mag. [4], vol. i, pp. 454-9. 

SEITZ, O., 1929. Kritische Bemerkungen zur homoomorphen Ammoniten-Terminologie. 

Jahrb. Preuss. Geol. Landesanst., vol. 1, pp. 148-54. 

SIMPSON, M., 1843. A Monograph of the Ammonites of the Yorkshire Lias. London. 

SPATH, L. F., 1919. Notes on Ammonites [general], Geol. Mag., vol. lvi, pp. 27-35, 

65-71, 115-22, 170-7, 220-5. 

, 1923. A Monograph of the Ammonoidea of the Gault, Part I, pp. 7-13. [Glossary 

and explanation of modern terms used in ammonite descriptions.] 

, 1923. On Ammonites from New Zealand [Lias-Tithonian ammointes and 

classification discussed]: Appendix to Trechman's Jurassic Rocks of N.Z. Q.J.G.S., 

vol. lxxix, pp. 286-312. 

, 1924. On the Blake Collection of Ammonites from Kachh, India. [Review of 

Families and Genera.] Mem. Geol. Surv. India, vol. ix, Memoir, No. 1, pp. 1-29. 

, 1927-32. Revision of the Jurassic Cephalopod Fauna of Kachh (Cutch). 

Ammonoidea. Parts i-vi, Mem. Geol. Surv. India, N.S., vol. ix, Memoir, No. 2. 

[Unfortunately the sixth and final part has not become available at the time of 

going to press.] 

SWINNERTON, H. H., & TRUEMAN, A. E., 1918. The Morphology and Development 

of the Ammonite Septum. Q.J.G.S., vol. lxxiii, pp. 26-58. 

THOMPSON, C., 1913. The Derived Cephalopoda of the Holderness Drift. Q.J.G.S., 

vol. lxix, pp. 169-83. [Revisions by L. F. Spath, 1925-6, in the Naturalist.] 

TRAUTH, F., 1927-31. Aptychenstudien. Annal. Naturhist. Mus. Wien, vol. xii, 

p. 171; vol. xiii, p. 121; vol. xliv, p. 329; vol. xiv, p. 17. 

TRUEMAN, A. E., 1922. Aspects of Ontogeny in Ammonite Evolution. Journal of 

Geology, Chicago, vol. xxx, pp. 140-3. 

WADDINGTON, C. H., 1929. Notes on Graphical Methods of Recording the Dimensions 

of Ammonites. Geol. Mag., vol. lxvi, pp. 180-6. 

WRIGHT, T., 1878-86. Monograph on the Lias Ammonites of the British Islands. 

Pal. Soc. 

, 1880. On the Modern Classification of the Ammonitidae. Proc. Cots. N.F.C., 

vol. vii, pp. 170-221. 

NAUTILOIDEA 

FOORD, A. H., & CRICK, G. C., 1890. Descriptions of new and imperfectly-defined 

species of Jurassic Nautili contained in the British Museum. Ann. Mag. Nat. Hist. 

[6], vol. v, pp. 270-90 and 388-409. 

SPATH, L. F., 1927. Revision of the Jurassic Cephalopod Fauna of Kachh (Cutch). 

Nautiloidea. Mem. Geol. Surv. India, N.S., vol. ix, Memoir No. 2, Part I,


pp. 19-35. [A Systematic revision of the fossil Nautiloidea, setting forth a 

general classification.] 

WILLEY, A., 1902. Contribution to the Natural History of the Pearly Nautilus. Zool. 

Results Materials from New Britain, New Guinea, Loyalty Islands, &c.; Cambridge 

Univ. Press, vol. vi, pp. 691-826. [Contains exhaustive references to bibliography 

of the Nautiloidea J 

BELEMNOIDEA 

HUXLEY, T. H., 1864. On the Structure of Belemnitidae; with a description of a more 

complete specimen of a Belemnites than any hitherto known, and an account of 

a new genus of Belemnitidae: Xiphoteuthis. Mem. Geol. Surv., Monograph ii. 

LISSAJOUS, M., 1925. Repertoire alphabetique des Belemnites jurassiques, precede 

d'un essai de classification. Travaux du Lab. de Geologie Fac. Sci. Lyon, Fasc. 

viii, Mem. 7, pp. 1-173. 

MILLER, J. S., 1826. Observations on Belemnites. Trans. Geol. Soc. [2], vol. ii, 

pp. 45-62. 

NAEF, A., 1922. Die fossilen Tintenfische. Jena. 

PHILLIPS, JOHN, 1865-1909. A Monograph of British Belemnitidae: Jurassic. Pal. Soc. 

THOMPSON, C., 1910. The Belemnites of the Yorkshire Lias. Trans. Hull Geol. 

Soc., vol. vi, pp. 99-102. 

BRACHIOPODA 

BUCKMAN, S. S., 1899. List of Types and Figured Specimens of Brachiopoda. Proc. 

Cots. N.F.C., vol. xiii, pp. 133-40. 

, 1901. Homoeomorphy among Jurassic Brachiopoda. Proc. Cots. N.F.C., 

vol. xiii, pp. 231-90. 

, 1904. Jurassic Brachiopoda. Ann. Mag. Nat. Hist. [7], vol. xiv, pp. 389-97. 

, 1906. Brachiopod Nomenclature. Ann. Mag. Nat. Hist. [7], vol. xviii, 

pp. 321-7. 

, 1907. Brachiopod Morphology: Cinctay Eudesia, and the Development of Ribs. 

Q.J.G.S., vol. lxiii, pp. 338-43. 

, 1916. Terminology for Foraminal Development in Terebratuloids. Trans. 

New Zealand Inst., vol. xlviii, pp. 130-2. [Brief Anticipation of next item.] 

, 1917. The Brachiopoda of the Namyau Beds, Northern Shan States, Burma. 

Mem. Geol. Surv. India, N.S., vol. iii, Memoir No. 2. [Numerous British Bathonian 

and other brachiopods figured.] 

DAVIDSON, T., 1851-84. British Fossil Brachiopoda, vols, i-v; Bibliography—vol. vi. 

1886. Pal. Soc. 

, 1862. On Scottish Jurassic Brachiopoda. Geologist, vol. v, pp. 443-5 and plate. 

DAVIDSON, T., & MORRIS, J., 1847. Descriptions of some Species of Brachiopoda. 

Ann. Mag. Nat. Hist., vol. xx, pp. 250-7. 

HUDLESTON, W. H., & WALKER, J. F., 1877. On the Distribution of the Brachiopoda 

in the Oolitic Strata of Yorkshire. Ann. Rept. Yorks. Phil. Soc. for 1876, pp. 7-12. 

MARSHALL, J. W. D., 1896. Notes on the British Jurassic Brachiopoda. Proc. Bristol 

Nat. Soc. [3], vol. viii, pp. 17-40. 

MOORE, C., 1860-1. On New [Jurassic] Brachiopoda, and on the development of 

the Loop in Terebratula. Geologist, vol. iii, p. 445, vol. iv, pp. 96-9, 190-4. 

MORRIS, J., 1846. On the Subdivision of the Genus Terebratula. Q.J.G.S., vol. ii, 

pp. 382-9. 

ROLLIER, L., 1915-19. Synopsis des Spirobranches (Brachiopodes) jurassiques Celto- 

Souabes. Mem. Soc. pal. Suisse, vols, xli-xliv. 

SAHNI, M. R., 1928. Morphology and Evolution of certain Jurassic Terebratulids. 

Ann. Mag. Nat. Hist. [10], vol. ii, pp. 114-38. 

TATE, R., 1869. Additions to the List of Brachiopoda of the British Secondary Rocks. 

Geol. Mag., vol. vi, pp. 550-6. 

WALKER, J. F., 1869-70. On Secondary Species of Brachiopoda. Proc. Yorks. Nat. 

Club, 1869, p. 214; Geol. Mag., vol. vii, 1870, pp. 560-4. 

, 1889. On Oolitic Brachiopoda new to Yorkshire. Ann. Rept. Yorks. Phil. Soc. 

for 1888, pp. 37-40. 

, 1893. On the Brachiopoda recently discovered in the Yorkshire Oolites. Ann. 

Rept. Yorks. Phil. Soc. for 1892, pp. 47-51.


POLYZOA 

GREGORY, J. W., 1894. Catalogue of the Jurassic Bryozoa in the York Museum [with 

figures]. Ann. Rept. Yorks. Phil. Soc. for 1893, PP- 58-61. 

, 1895-6. A Revision of the British Jurassic Bryozoa. Ann. Mag. Nat. Hist. [6], 

vol. xv, pp. 223-8; vol. xvi, pp. 447-51 ; vol. xvii, pp. 41-9, 151-5, 194-201,287-95. 

, 1896. Catalogue of the Fossil Bryozoa in the Department of Geology, British 

Museum. Jurassic Bryozoa. London. 

LANG, W. D., 1904. Jurassic forms of the 'Genera' Sto?natopora and Proboscina. Geol. 

Mag. [5], vol. i, pp. 315-22. 

, 1905. On Stomatopora antiqua Haime and its Related Liassic Forms. Geol. 

Mag. [5], vol. ii, pp. 258-68. 

, 1913. Report of a visit to the exhibits of Polyzoa and corals in the Geological 

Department of the British Museum. P.G.A., vol. xxiv, pp. 189-93 [with many 

references]. 

LONGE, F. D., 1881. On the Relation of the Escharoid Forms of Oolitic Polyzoa to the 

Cheilostomata and Cyclostomata. Geol. Mag. [2], vol. viii, pp. 23-34. 

VINE, G. R., 1880-1. A Review of the Family Diastoporidê for the Purpose of 

Classification. Q.J.G.S., vol. xxxvi, pp. 356-61; and Further Notes: Species from 

the Lias and Oolites, vol. xxxvii, pp. 381-90. 

, 1883. Third Report of the Committee on Fossil Polyzoa. Rept. Brit. Assoc. 

for 1882, p. 249. 

, 1886-7. Jurassic Polyzoa in the Neighbourhood of Northampton [Inferior 

Oolite to Oxford Clay]. Journ. Northants Nat. Hist. Soc., vol. iv, pp. 202-11; and 

in the Gayton Boring, Northants, ibid., 1887, pp. 255-66. 

ECHINODERMA TA 

CARPENTER, P. H., 1882. On some New or little-known Jurassic Crinoids. Q.J.G.S., 

vol. xxxviii, pp. 29-43. 

CRONIES, C., & MCCORMACK, J., 1932. Fossil Holothuroidea [with useful bibliography]. 

Journ. Palaeont., vol. vi, pp. 111-48. 

DEECKE, W., 1928. Uber die Jura-Seeigel. Palaeobiologica, vol. i, pp. 419-56. 

FORBES, E., 1844. On the Fossil Remains of Starfishes of the Order Ophiuridae, found 

in Britain. Proc. Geol. Soc., vol. iv, pp. 232-4. 

HAWKINS, H. L., 1912. Classification, Morphology and Evolution of the Echinoidea 

Holectypoidea. Proc. Zool. Soc., 1912, pp. 440-97. 

, 1917. Morphological Studies in the Echinoidea Holectypoidea and their Allies. 

I. Pygaster and Plesiechinus. Geol. Mag. [6], vol. iv, pp. 160-9. 

II. Discoides and Conidus. Ibid., pp. 196-205. 

III. Holectypus. Ibid., pp. 249-56. 

IV. Pygasteridae. Ibid., pp. 342-50. 

, 1919. The Morphology and Evolution of the Ambulacrum in the Echinoidea 

Holectypoidea [with bibliography]. Phil. Trans. Roy. Soc., vol. ccix B, pp. 377-480. 

M'COY, F., 1848. On some New Mesozoic Radiata. Ann. Mag. Nat. Hist. [2], 

vol. ii, pp. 397-420. 

MOORE, C., 1873. On the Presence of [Holothuria] in the Inferior Oolite and Lias. 

Rept. Brit. Assoc. for 1872, pp. 117-18. 

UPTON, C., 1917. Notes on Chirodota-Spicules [a Holothurian] from the Lias and 

Inferior Oolite. Proc. Cots. N.F.C., vol. xix, pp. 115-18. 

WHITEAVES, J. F., 1861. On the Oolitic Echinodermata of the Neighbourhood of 

Oxford. Geologist, vol. iv, pp. 174-5. 

WRIGHT, T., 1851-3. On the Cidaridae and Cassidulidae of the Oolites, with Descriptions 

of some New Species of those Families. Ann. Mag. Nat. Hist. [2], vol. viii, 

pp. 241-80, and vol. ix, pp. 81-103 \ anc * ^53, Proc. Cots. N.F.C., vol. i, pp. 134-229. 

, 1854. Contributions to the Palaeontology of Gloucestershire. A Description and 

Figures of some New Species of Echinodermata from the Lias and Oolites. Ann. 

Mag. Nat. Hist. [2], vol. xiii, pp. 161-73, 312-24, 376-83. 

, 1857-80. Monograph on the British Fossil Echinodermata of the Oolitic 

Formations. Pal. Soc.


WRIGHT, T., i860. On a new Genus of Fossil Cidaridae (Hemipedina), with a Synopsis 

of the Species included therein, and on some New Species from the Oolites. Proc. 

Cots. N.F.C., vol. ii, pp. 121-30. 

, i860. A Description of some New Species of Echinodermata from the Lias and 

Oolites. Proc. Cots. N.F.C., vol. ii, pp. 17-48. 

COELENTERA: CORALS 

DUERDEN, J. E., 1902-6. The Morphology of the Madreporaria. [Series of papers: 

for full references see:] Ann. Mag. Nat. Hist. [7], vol. xviii, p. 226 (1906). 

FAUROT, L., 1909. Affinites des Tetracoralliaires et des Hexacoralliaires. Ann. de 

Pateont., vol. iv, pp. 69-107. 

GREGORY, J. W., 1900. Jurassic Fauna of Cutch., vol. ii, part ii, The Corals. Mem. 

Geol. Surv. India, Ser. ix. [Contains modern revision of systematics and nomenclature.] 

LANG, W. D., 1917. Homceomorphy in Fossil Corals. P.G.A., vol. xxviii, pp. 85-94. 

MILNE-EDWARDS, H., & HAIME, J., 1850-4. A Monograph of the British Fossil 

Corals. And Supplement by DUNCAN, P. M., 1866. 

TOMES, R. F., 1900. Contributions to a History of the Mesozoic Corals of the County 

of York. Proc. Yorks. Geol. Soc., vol. xiv, pp. 72-85. 

WRIGHT, T., 1867. On Coral Reefs Present and Past. Proc. Cots. N.F.C., vol. iv, 

pp. 97-173. 

PORIFERA (SPONGES) 

HINDE, G. J., 1883. Catalogue of the Fossil Sponges in the British Museum. 4to. 

London. 

, 1887-1912. A Monograph of the British Fossil Sponges. Pal. Soc. 

PROTOZOA: FORAMINIFERA 

CRICK, W. D., & SHERBORN, C. D., 1891. On some Liassic Foraminifera from 

Northamptonshire. Journ. Northants N.H.S., vol. vi, pp. 208-14. 

JONES, T. R., 1882. Catalogue of the Fossil Foraminifera in the British Museum. 

8vo. London. 

JONES, T. R., & PARKER, W. K., 1871. On Terquem's Researches on the Foraminifera 

of the Lias and Oolites. Ann. Mag. Nat. Hist. [4], vol. viii, pp. 361-5. 

, 1875. List of some English Jurassic Foraminifera. Geol. Mag. [2], vol. ii, 

pp. 308-11. 

JONES, T. R., & SHERBORN, C. D., 1886. On the Microzoa found in some Jurassic 

Rocks of England. Geol. Mag. [3], vol. iii, pp. 271-4. 

PLANTS 

ARBER, E. A. N., & PARKIN, J., 1907-8. On the Origin of Angiosperms. Journ. Linn. 

Soc., vol. xxxviii, p. 29, 1907. Studies on the Evolution of the Angiosperms. Ann. 

Bot., vol. xxii, p. 48, 1908. 

BROWN, A., 1894. On the Structure and Affinities of the Genus Solenopora, with 

Descriptions of New Species. Geol. Mag. [4], vol. i, pp. 145-51. 

CARRUTHERS, W., 1867. On Gymnospermatous Fruits from the Secondary Rocks of 

Britain. Journ. Botany, vol. v, pp. 1-21. 

, 1867-9. On some Cycadian Fruits from the Secondary Rocks of Britain. Geol. 

Mag., vol. iv, pp. 101-6, and vol. vi, pp. 97-9. 

, 1869. On some Undescribed Coniferous Fruits from the Secondary Rocks of 

Britain. Geol. Mag., vol. vi, pp. 1-7. 

, 1870. On the Fossil Cycadean Stems from the Secondary Rocks of Britain. 

Trans. Linn. Soc., vol. xxvi, pp. 675-708, and Geol. Mag., vol. vii, pp. 573-7. 

GARDNER, J. S., 1886. On Mesozoic Angiosperms [Williamsonia, &c.]. Geol. Mag. 

[3], vol. iii, pp. 193-204, 342-5. 

GARWOOD, E. J., 1931. Important Additions to our Knowledge of the Fossil Calcareous 

Algae since 1913. . . . Q.J.G.S., vol. lxxxvii, Jurassic, pp. xcii-xcvii [w r ith 

bibliography]. 

HARRIS, G. F., 1896. The Analysis of Oolitic Structure. P.G.A., vol. xiv, p. 59.

PALAEOGEOGRAPHY 669 

SCOTT, D. H., 1907. The Flowering Plants of the Mesozoic Age, in the Light of Recent 

Discoveries. Journ. Roy. Micro. Soc., pp. 129-41. 

SEWARD, A. C., 1892. Fossil Plants as Tests of Climate. London. 

, 1894. Notes on the Bunbury Collection of Fossil Plants. Proc. Phil. Soc. 

Cambridge, vol. viii, part 3, p. 187. 

, 1898-1919. Fossil Plants. Cambridge. 

, 1900. Notes on some Jurassic Plants in the Manchester Museum. Mem. 

Manchester Lit. and Phil. Soc., vol. xiv, part 3, p. 1. 

, 1900-4. Catalogue of the Mesozoic Plants in the Department of Geology, 

British Museum: vol. i, 1900, Jurassic Flora of Yorkshire Coast; vol. ii, 1904, 

Jurassic Flora outside Yorkshire. 

, 1901-2. Jurassic Flora of East Yorkshire. Rept. Brit. Assoc. for 1900, p. 756; 

and for 1901, p. 856; also Geol. Mag. [4], vol. viii, p. 36. 

, 1910. Comparisons of Jurassic Floras. Nature, vol. lxxxv, pp. 258-9. 

, 1911. The Jurassic Flora of Yorkshire. Naturalist, 1911, pp. 1-8, 85-94. 

, 1924. Later Records of Plant Life: Post-Carboniferous Floras. Q.J.G.S., 

vol. Ixxx, pp. lxxxix-xcvii. 

, 1931. Plant Life through the Ages. Cambridge [Jurassic Period, ch. xiv, 

PP-335-69]. 

STOPES, M. C., 1912. Petrifications of the [then] Earliest European Angiosperms. 

Phil. Trans. Roy. Soc., vol. cciii B, pp. 75-100. 

WETHERED, E., 1889. On the Microscopic Structure of the Jurassic Pisolite. Geol. 

Mag. [3], vol. vi, pp. 196-200. 

, 1895. The Formation of Oolite. Q.J.G.S., vol. Ii, pp. 196-209. 

P A L A E O G E O G R A P H Y 

ANDREE, K., 1913, Die palaogeographische Bedeutung sediment-petrographischer 

Studien. Peterm. Mitteil., Jahrg. lxi, vol. ii, p. 121. 

ARLDT, T., 1917-21. Handbuch der Palaogeographie. Berlin (Borntraeger). 

BRINKMANN, R., 1924. Der Dogger und Oxford des Siidbaltikums. Jahrb. Preuss. 

Geol. Landesanst., vol. xliv, pp. 477-513. 

BUCKMAN, S. S., 1922-3. [British Jurassic] Palaeogeography [with map]. Type 

Ammonites, vol. iv, pp. 20-5, and 52-4. 

CRICKMAY, C. H., 1931. Jurassic History of North America: its Bearing on the 

Development of Continental Structure. Proc. Amer. Phil. Soc., vol. lxx, pp. 15-102. 

DACQUE, E., 1913. Palaogeographische Karten und die gegen sie zu erhebenden 

Einwande. Geol. Rundschau, vol. iv, pp. 186-206. 

, 1915. Grundlagen und Methoden der Palaogeographie. Jena, 1915. 

DAVIS, W. M., 1895. The Development of Certain English Rivers. Geograph. Journ., 

vol. v, pp. 127-46 [peneplains described]. 

, 1896. The Peneplain of the Scotch Highlands. Geol. Mag. [4], vol. iii, 

pp. 525-8. 

DUTERTRE, A. P., 1926. Les Aucelles de terrains jurassiques superieurs du Boulonnais. 

Bull. Soc. geol. France [4], vol. xxvi, pp. 395-408 [with discussion of boreal 

connexion]. 

FREBOLD, H., 1930. Verbreitung und Ausbildung des Mesozoikums in Spitzbergen. 

Skrifter om Svalbard og Ishavet, No. 31, 1930; also No. 20, 1929. [Numerous 

palaeogeographical maps and discussion.] 

FRECH, F., 1902. Studien uber das Klima der geologischen Vergangenheit. Zeitschr. 

Gesell. fur Erdkunde, 1902, pp. 611-93. 

GOODCHILD, J. G., 1889. An Outline of the Geological History of the Eden Valley. 

P.G.A., vol. xi, pp. 277-8, and Trans. Cumb. and Westm. Assoc., no. xiv, 

pp. 73-90. 

GOTHAN, W., 1912. Die Frage der Klimadifferenzierung im Jura und in der Kreideformation 

im Lichte palaobotanischer Tatsachen. Jahrb. Preuss. Geol. Landesanst., 

vol. xxix, p. 220. 

GREEN, J. F. N., 1920. The Geological Structure of the Lake District. P.G.A., 

vol. xxxi, pp. 109-26.


GREGORY, J. W., 1907. Climatic Variations, their Extent and Causes. Compte rendu, 

Congres geol. int., 1906, Mexico, p. 474. 

GROVES, A. W., 1931. The Unroofing of the Dartmoor Granite and the Distribution 

of its Detritus in the Sediments of Southern England. Q.J.G.S., vol. lxxxvii, 

pp. 62-96. 

HUBBARD, G. D., & WILDER, C. G., 1930. Validity of the Indicators of Ancient 

Climates. Bull. Geol. Soc. America, vol. xii, pp. 275-92. 

JONES, O. T., 1931. Some Episodes in the Geological History of the Bristol Channel 

Region. Presid. Address, Sect. C; Rept. Brit. Assoc. for 1930, pp. 57-82. 

JUKES-BROWNE, A. J., 1911. The Building of the British Isles. 3rd ed. 

JUNGST, H., 1927. Die Meeresverbindung Nord-Sud-Deutschland in der Psiloceraten- 

Zeit. Neues Jahrb. fur Min., &c., B.-B. lviii, Abt. B, pp. 171-214. 

KAUENHOWEN, W., 1927. Die Faziesverhaltnisse und ihre Beziehungen zur Erdolbildung 

an der Wende Jura-Kreide in Nordvvestdeutschland. Neues Jahrb. fur 

Min., &c., B.-B. lviii, Abt. B, pp. 215-72. 

LAPPARENT, A. DE, 1906. Traite de Geologie, vol. ii. 

MARR, J. E., 1906. The Influence of the Geological Structure of the English Lakeland 

upon its Present Features. Q.J.G.S., vol. lxii, pp. lxvi-cxxviii. 

, 1929. Deposition of the Sedimentary Rocks. 

NEUMAYR, M., 1883. Ueber klimatische Zonen wahrend der Jura- und Kreidezeit. 

Denkschr. k. Akad. Wiss. Wien, M.-N. Klasse, vol. xviii, pp. 277-310. 

, 1885. Die geographische Verbreitung der Juraformation. Denkschr. k. Akad. 

Wiss. Wien, vol. 1, pp. 57-142. 

ORTMANN, A. E., 1896. An Examination of the Arguments given by Neumayr for the 

Existence of Climatic Zones in Jurassic Times. American Journ. Sci. [4], vol. i, 

pp. 257-70. 

POMPECKJ, J. F., 1908. Die zoogeographischen Beziehungen zwischen den Jurameeren 

Nordwest- und Siiddeutschlands. 1. Jahresber. Niedersiichs. Geol. Ver. Hannover, 

p. 10. 

RICHARDSON, L., 1903. Mesozoic Geography of the Mendip Archipelago. Proc. Cots. 

N.F.C., vol. xiv, pp. 59-72. 

SALFELD, H., 1921. Das Problem des borealen Jura und der borealen Unterkreide. 

Centralblatt fur Min., &c., vol. xxii, pp. 169-74. 

SAWICKI, L., 1912. Die Einebnungsflachen in Wales und Devon. Sitzungsber. 

Warschauer Gesell. Wiss., Lief. 2, pp. 123-34. 

SCHOTT, W., 1930. Palaogeographische Untersuchungen iiber den Oberen Braunen 

und Unteren Weissen Jura Nordwestdeutschlands. Inaugural-Dissertation, 

Gottingen, 1930; and Abh. Preuss. Geol. Landesanst., N.F., vol. exxxiii. 

SCHUCHERT, C., 1915. Climates of Geologic Time. Ann. Rept. Smithsonian Inst, for 

1914, pp. 277-311. 

SEMPER, M., 1908. Die Grundlagen palaogeographischer Untersuchungen. Centralblatt 

fur Min., &c., vol. ix, pp. 434-45. 

SORBY, H. C., 1852. On the Direction of Drifting of the Sandstone Beds of the Oolitic 

Rocks of the Yorkshire Coast. Proc. Yorks. Phil. Soc., vol. i, pp. 111-13. 

TRAVIS, C. B., 1914. Some Evidences of Peneplanation in the British Isles. Proc. 

Liverpool Geol. Soc. (Presid. Address), vol. xii, pp. 3-31. 

TROTTER, F. M., & HOLLINGWORTH, S. E., 1928. The Alston Block. Geol. Mag., 

vol. lxv, pp. 433-47. 

TROTTER, F. M., 1929. The Tertiary Uplift of the Alston Block. Proc. Yorks. Geol. 

Soc., N.S., vol. xxi, pp. 161-80. 

UHLIG, V., 1911. Die marinen Reiche des Jura und der Unterkreide. Mitteil. Geol. 

Gesell. Wien, vol. iv, pp. 329-448. 

WATTS, W. W., 191 I. Geology as Geographical Evolution. Q.J.G.S., vol. lxvii, 

pp. lxii-xciii. 

WILLIS, B., 1910. Principles of Palaeogeography. Science, N.S., vol. xxxi, pp. 241-60. 

WILLS, L. J., 1929. The Physiographical Evolution of Britain. London. 

WOOD, S. V., 1862. On the Form and Distribution of the Land-Tracts during the 

Secondary and Tertiary Periods respectively. . . . Phil. Mag. [4], vol. xxiii, 

pp. 161-71, 269-82, 382-93.

SUBJECT INDEX 

Note: To keep the index within reasonable bounds, place-names are not 

included, but the page headings are intended to act as a geographical as well 

as a stratigraphical guide. The order of describing each formation is from 

south to north—from Dorset to Yorkshire and Scotland, and lastly the Weald 

of Kent. 

The only personal names indexed are those of certain pioneers, whose work 

is specially dealt with in Part I. 

Aalenian Denudation, 90, 93, 191-2, 198: 

and see Bajocian Transgression 

Ages, 23-5; tables of, 24, 546 

Aires d'ennoyage (Haug), 59 

Albian Transgression, 73, 95-6, 500, 

577-9 

Alston Block, 588-90 

Alum, 181, 182, 441-3 

Ammonites: value as zonal indices, 14-15, 

35; difficulties of nomenclature, 17; 

rate of dispersal, 29, 564; distribution 

in time and space in British Jurassic, 

562-7; autochthony, 562-6; relation to 

coralline and 'estuarine' sediments, 

562-7 

Aptian Transgression, 73, 95-6, 409, 467, 

535, 545-7 

Armorican Axes, 61, 68-79, 575 

Atlantis, 567 ff. 

Axes of Uplift, 59 ff.; principal axes, 61; 

classification by directrix, 61, 87; 

periods of activity, 87; dominance over 

other movements, 575; discrimination 

from other uplifts, 575-6; in Germany, 

598; in France, 598 

Bajocian Denudation, 71, 90-1, 190-3, 

197-8, 230, 233, 238-42: and see 

Vesulian Transgression 

Bajocian Transgression,90-1,93,189,198, 

201, 212: and see Aalenian Denudation 

Bean, W., 15 

Bewcastle Anticline, 588-9 

Biochron, 22, 34 

Bioherm, 615 

Biostrome, 615 

Biozone: definition, 22; emended meaning, 

22, 34; chronological equivalent of 

(biochron), 22; use with lineages, 33, 

354 

Birdlip Axis, 75-7, 82, 174, 198-9, 240, 

278, 459 

Borings (for Wealden Borings see Weald) 

Batsford (Lower Lemington), 66, 131 

Bletchley, 40, 42-3, 46, 79-80, 350 

Bradford-on-Avon, 41 

Brantingham, 215 

Brigg, 85, 311, 356 

Borings (contd.) 

Buckland Denham, 269, 270 

Burford, 40, 133, 157 

Calvert, 40, 43, 46, 66, 93, 133, 177, 

209,324-5, 335, 350 

Caythorpe, 176 

Culford, 40 

Donnington on Bain, 469-70 

I Ferrieres-en-Bray, 49, 52-3 

Harwich, 40 

1 Hemington, 261-2, 280 

1 Highworth (Red Down), 395, 439 

i Kentish Town, 40 

j Little Missenden, 40 

London, 40, 41, 323-4 

; Lowestoft, 40 

: Lyme Regis, 41 

! Mickleton, 66, 133 

! North Ferriby, 419, 470 

j Oakham, 176 

1 Olney, 209 

Richmond, 40, 46, 323-4 

! Southampton, 41 

! Southerv, 177, 210, 325, 351, 417, 468 

i Stony Stratford, 43, 209 

Stowell, 195, 256, 258-9, 262 

j Streatham, 40, 323-4 

Sub-Wealden, see Weald 

> Swindon, 269, 344, 346, 395, 397 

| Tottenham Court Rd., 40, 323-4 

Turn ford, 40 

! Ware, 40 

| Wealden borings: see Weald 

j Westbury, 156, 200, 261-2, 281, 344, 

j 391,564 

Wincanton, 256, 258-9, 262 

Wytham, 66, 175 

Boulder Beds (in Scottish Kimeridgian), 

474-7, 480 

Bower Chalke Pericline, 72 

Brachiopods: rate of dispersal, 29; value 

as zonal indices, 30, 199; colonial 

habits, 249, 199, 328 

Bristol Channel: structure of, and palaeogeography, 

568, 570-6 

Brixton Anticline, 73 

Brongniart, A., First use of stratal names 

in -ien, 9, 11, 12 

3 A

672 SUBJECT INDEX 

Buckland, Dean William: stratal table, 7; j 

Stonesfield mammals, 296-7 j 

Buckman, S. S.: life, 19; chronology, ( 

20 ff. and 36-7; Type Ammonites, 15, ; 

1 7f 37,' on distribution of ammonites, j 

562; on tectonics, 56, 61, 65, 69, 74, 90, ! 

563-5; principal stratigraphical work: 

Lower Lias, 139-40; Middle Lias, 153- j 

5; Upper Lias, 165-70, 172-6, 181-7; ; 

Inferior Oolite, 190-1, 193, 197-200, j 

205, 221, 225-8, 233-5, 237, 239-42; ! 

Great Oolite, 257-8, 263 ; Oxford Clay, 

343, 347, 362-3, 368; Corallian, 384, 

406, 408, 409, 411, 427, 434; Kime- , 

ridge Clay, 445, 465-6, 477, 47$; : 

Portland Beds, 491, 507, 510-14; ter- | 

minology, 616 ! 

Building Stones and Freestones : Rhaetic, j 

103; Lias, 126-7, 128, 148-9, 157, 162, | 

163, 169, 173; Inferior Oolite, 192, j 

194-5, 197,201-4,208,212-16,220-8, I 

231-2, 234, 236, 238, 241-4; Great : 

Oolite, 256-8, 266-7, 271-7, 284-92, 

293-6, 301, 3° 6 , 307, 313, 317; Corn- j 

brash, 328, 330, 331, 335-6; Oxford 1 

Clay, 367; Corallian Beds, 380-1, j 

387-8, 390-1, 393-4, 397-4oi, 405, | 

415-16, 422-9; Portland Beds, 483-8, j 

493-4, 498, 5 OI -2, 503-4, 5°5'6, 511, 

513-14; Purbeck Beds, 518, 520-1, 

524-5, 529-30, 532-3, 537; Wealden, 

549 

Caistor Axis, 84-5, 311-12 ! 

Caledonian Axes, 61, 85-7 j 

Callovian Transgression, 91-2, 94, 312, j 

327 ; 

Calvert Borings, see Borings 

Chaldon Anticline, 73, 498, 530 j 

Charnian Axes, 61, 79-84 

Charnwood Axis, 79-81, 157, 335 ' 

Charnwood Forest, as land in Rhaetic, j 

111,582,583 j 

Cimmerian movements, 89-90, 92-4 j 

Cleeve Hill Syncline, 75, 198-9, 240 j 

Cleveland Axis, 84 

Coal, 218,317,319-20,441-3,447-9,470 j 

Cole Syncline, 71, 195, 236 

Conglomerates: see Pebble Beds | 

Conybeare, W., D., 3, 54, 238, 403 ! 

Coral Fauna, 397, 400, 412, 561-2 

Coral reefs: as indicators of depth, 53, j 

558; distribution in time and space in ; 

Britain, 559-61; classification, 558; , 

special fauna of, 397, 400, 412, 561-2; i 

relation to ammonite distribution, 562, • 

566-7 ; nomenclature, 615 j 

Cyclic sedimentation, 54 ff. j 

Dachbank, 56-8 i 

Dartmoor, elevation and unroofing of, 

576-9 

Dean Hill Pericline, 72 

Deister Phase, 90, 92, 94-5 

Deltaic deposits, 314-16, 216-20, 596-7 

Derivation of sediments: 

from Wales, 102-3,108,125,172,173-4 

from Dartmoor and Cornwall, 499,531, 

54o, 542, 576, 579 

from London landmass, 50, 209, 402-3, 

408, 515, 541-2, 582, 597-8 

from Fennoscandia, 581, 586, 597 

from Pennines, 580-2, 586 

from Charnwood Forest, 111, 582 

from Brittany, 174, 499 

from Mendip Archipelago, 103-5, 

125-6 

Dispersal of organisms, rate of, 29, 564 

Dissimilar Faunas, principle of, 27, 30; 

objections to, 31 ff. 

English Channel: palaeogeography, 568 

Epeirogenic movements, 88-9 

Epibole, 2i, 34 

Exmoor, tectonic history of, 574-6 

Fallen Stack, 474-5 

Faults : Pennine, Craven, Dent and Stublick 

Faults, 587-90; Glen More and 

Central Valley, 593-4; Ord Fault, 

475-6; Malvern Fault, 569-76; Peak 

Fault, 84, 180-2; Purbeck Thrust 

Fault, 49, 73; Hebrides, 50, 593~5; 

Mendips, 68; Dorset, &c. (pre-Cretaceous), 

46, 95-6, 250-1 

Faunizone, 23, 34, 56 

Fennoscandia, 586, 596-9 

Fitton, W.H., 8, 466, 489, 502, 509, 531, 

536,555 

Fossil-beds: tectonic significance, 56, 

353; chronological significance, 97-8, 

353 

Freestones: see Building Stones 

Geanticline, def., 58 

Geochron, 22 

Geosynclines: def., 58, 616; subsidence 

of, 574-6, 583,58577, 594,598-9; types 

of, 616; pre-Jurassic, 588-9 

Godwin-Austen, R. A. C., prediction of 

buried structures, 39-40, 42, 59, 69 

Goring Gap Syncline, 83-4 

Great Oolite Transgression, 94, 320, 

324-5 

Heavy Minerals: see Derivation of sediments. 

Hemera: definition, 20; stratal equivalent, 

21; time of duration, 29; criticism, 32 

Hils Phase, 90

Howardian Anticlines, 86-7 I 

Hunton, Louis, early zonal work, 8, 9, 1 

14,15 I 

Ibberton Anticline, 84 j 

Irish Sea, Jurassic in bed of, 568 \ 

Iron Ores: Lower Lias, 136-7; Middle j 

Lias, 157-8,160-1; Upper Lias, 183-7; 

Inferior Oolite, 206-9, 214, 216, 217; j 

Great Oolite, 307; Cornbrash, 337; ; 

Oxford Clay, 373"4; Corallian, 385,389, j 

395-6, 437; Kimeridge Clay, 452-3 ! 

Islip Axis, 85-7, 333 I 

Jet, 181, 182-3, I8 5 ! 

Jurolaurentia, 568 j 

Kingsclere Pericline, 69, 83 | 

Kratogen, kratogenic movements, 616 j 

Lake District, palaeogeography of, 584-91 j 

Law of Planes of Horizontality (Lamp- | 

lugh), 53 | 

Lineages, value in stratigraphy, 33~4,35, I 

353-4 | 

London-Ardennes Island or landmass: ; 

see London platform j 

London platform: structure and comparison 

with Plateau of Brabant, 41; as j 

Jurassic land, 42, 46, 574~6; borings ^ 

into, 40, 323-4; transgressions round j 

and over, 543-4, 574; as source of ! 

sediment, see Derivation of sediments 

Lonsdale, W., 55 ! 

Louth-Willoughby Axis, 84-5, 311-12 

Malvern Axis, 67-8, 82, 563-5, 569 

Malvern Fault, 569, 576 

Malvernian Axes, 61, 64-8 

Mammals, 101, 105, 296-7, 526-7, 544 

Maps, earliest geological, 3 

'Marbles': Cotham or Landscape, 107; 

Marston, 123; Banbury, 134, 559; 

Forest (of Wychwood), 286-8; Alwalton, 

306; Purbeck, 518,521; Sussex, 542 

Market Harborough Axis, 79 

Market Weighton Axis, 62-4, 111-12, 

137-8, 159, 179, 215, 311-12, 337-8, 

358-9, 419-20, 423, 470-1, 564, 591 

Martelli Transgression ,94,347-8,412,427 

Melton Mowbray Axis, 77-8 

Mendip Axis, 68-71, 104-5, 128, 131, 

156, 170-2, 195, 237-9, 261-2, 268, 

330-1, 563-5 

Migration of organisms, 12, 32-4; of 

ammonites, 564-7 

Moment or Zone-Moment, 21, 34 

North Devon Axis, 71-2, 195, 236, 563, 

565, 574-6 

Nuneaton Axis, 79-81, 110, 135, 335 

SUBJECT INDEX 673 

Oil Shale: Dun Caan, 318; Kimeridge, 

440-3, 447-9, 452, 454, 468-70, 479 

Oppel, Albert, 12, 13, 15-19; table of 

zones, 18; on stratigraphy, 327,345,363 

Orbigny, Alcide d\ 8-14; table of stages, 

11; complete list, 617 ff.; first use of 

zones, 16 

Ord Fault (movements in Jurassic), 473, 

475-6, 480 

Orogenic movements, 88-9, 616 

Oscillations, 90 

Osnabriick Strait, 598-9 

Osterwald Phase, 90, 92, 95 

Ostracods, value as zonal indices, 519-20, 

536 

Oxford Axis, 80, 81, 403-9 

Painswick Syncline, 75, 82, 198-9, 240 

Palaeogeography, 557 ff. 

Palaeozoic platform of South-Eastern 

England, 40 ff., 574-6: and see London 

platform 

Pays de Bray Anticline, 49, 52-3 

Peak Fault, 180-2 

Pebble Beds, Conglomerates and Remanie 

Beds: in Rhaetic, 102-5, 111, 582; in 

Lias, 109, 125-6, 129, 135, 151, 158-9, 

164, 167, 168, 171, 178, 185, 187, 

350-1; in Inferior Oolite, 93, 190-2, 

T 95, j 98, 201, 207, 211, 214, 216, 224, 

233, 237, 240, 244, 246; in Great 

Oolite, 253, 269, 283-4, 289, 295, 

297-300, 317, 322; in Cornbrash, 327, 

332, 336, 339; in Oxford Clay (350?), 

360, 371, 372; in Corallian, 94, 391-2, 

393, 394, 396, 398-9, 402, 408, 412, 

429; in Kimeridge Clay, 94-5, 440, 

456-7, 458, 460, 474-7, 480; in Portland 

Beds, 95, 455-6, 460, 463-7, 481, 

504-5> 507-8, 510, 513-15, 517; IN 

Purbeck Beds, 528, 530, 534, 535, 537; 

in Cretaceous, 467, 540, 54 I_ 2, 545, 

547 

Peneplains: definition and spelling, 616- 

17; in Wales, 571-3, 576, 580; under 

London, 574-6; on Dartmoor, 579; on 

Pennines and Lake District, 589-91; in 

Scotland, 592 

Pennine Axis, 67, 82, 580-90 

Phillips, John, 3, 8, 54-5 

Phillips, William, 3, 7, 54 

Pisolite, 197, 204, 381, 388 

Plains (and planes) of erosion, 616-17: and 

see Peneplains 

Plateau of Brabant, 41-2 

Polyhemeral System of correlation, 26-37 

Ports Down Anticline, 72 

Purbeck Anticline, 73-4, 441, 450-1, 453 

Purbeck Thrust Fault, 49, 73, 483, 521, 

523,528

674 

Purton Axis, 67, 80, 393~5, 4°3 

Quenstedt, F. A., 11, 14, 15, 36 

Regressions, 92 

Remanie Beds: see Pebble Beds 

Rhaetic Transgression, 92, 93, 554, 598 

Rhythmic deposition, 54-9 

Ridgeway Fault, 73 

Rigid Block of N.W. Yorkshire, 587-90 

Sandown Anticline, 73 

Saxonian movements, 46, 89, 92 : and see 

Cimmerian 

Scissum Transgression, 93, 207 

Scottish Highlands, Jurassic history of, 

591-6 

Secule, 21, 34 

Sedgley-Lickey Axis, 79-83, 135, 4°3 

Sediments, sources of: see Derivation of 

sediments 

Shalbourne Pericline, 69, 83 

Shale Line, the, 161 

Simpson, Martin, early work on Yorkshire 

Lias, 15 

Sinemurian Denudation, 131, 93 

Smith, William: 1-7, Tables of strata, 

4 and 3-5 ; first geological map of Bath 

district, 3; as palaeontologist 8; on 

stratigraphy j 230, 263, 268, 278, 288, 

326,335,346,363,395 

Sohlbank, 56-8 

Stages, d'Orbigny and origin of, 9-12; 

criticisms of, 11-13, 1; list of stage 

names applied to the Jurassic, 617-22 

Stratigraphical nomenclature, 1-2 

Subsidence, of troughs, 53 ff., 616; differential, 

59 ff. 

Tectonics, 42-96; intra-Jurassic, 51 ff.; 

epeirogenic movements, 51 ff.; orogenic 

movements, 59 ff.; discrimination and 

classification, 87 ff., 574-6; summary of 

history in Jurassic, 93-6: see also Axes 

of Uplift, Geosynclines, Faults 

Teilzone, 33-4 

Tension, in Miocene orogeny, 49 

Tertiary movements: faulting, 50; folding, 

42-6, 50; thrusting, 49, 69, 73, 483, 

528; elimination of, 42-6, 50 

Tethys, 554 

Time factor, in dispersal, 29; in relative 

values of zonal units, 35 

Time terms, list of, 34 

Townsend, Rev. Joseph, 5 

Transgressions, 91-2 

Tripartite Series, 54 

Troughs of deposition and subsidence: 

see Geosynclines. 

SUBJECT INDEX 

! Vale of Bourton Axis, 64, 199 

! Vale of Moreton Axis, 64-7, no, 157, 

| 175-6, 198, 205-6, 245, 33i, 583, 586 

; Vale of Pewsey Anticline, 69, 72, 73, 455, 

j 504-5,575 

I Vale of Wardour Anticline, 72, 73, 389, 

.454, 500-4, 531-4, 574-6 

: Vesulian Transgression, 91, 93, 189-90, 

! 199 (fig- 36), 230-1, 233-6,238-41, 243, 

245-7: and see Bajocian Denudation 

Wales, palaeogeography of, 569-76 

Washout channels, 315, 220 

Weald: structure 0^47,575-6; borings in: 

Abbotscliff, 479-80 

Ashford, 436 

Battle, 52, 515-16, 538 

Bere Farm, 320, 373, 439 

Bishopsbourne, 150, 188 

Bobbing, 320-2 

Brabourne, 320-2,150-2,164,188,246, 

373,436-9,479-8o,515-17, 538, 558 

Chilham, 320, 373, 439 

Chilton, 150-1, 164, 188, 373, 439 

Dover, 320, 152, 164, 188, 246-7, 373, 

436-9, 479-8o, 558 

Elham, 152, 164, 188, 436 

Folkestone, 150, 164, 188, 436 

Fredville, 320, 150, 373, 439 

Guildford, 339, 373, 439 

Harmansole, 320-1, 150, 164, 373 

Hothfield, 538 

Ottinge, 479, 515-16 

Oxney, 320 

Penshurst, 52, 479, 515-17, 538, 543 

Pluckley, 52, 479, 515-16, 538 

Ropersole, 188 

Snowdown Collieries, 246, 373, 439 

Sub-Wealden, 40, 538 

Tilmanstone, 320-2, 246, 339 

Wealden lake, 51, 541-4, 553~6 

Webster, Thomas, 6 

Weymouth, Purbeck and Isle of Wight 

Axis, 73-5, 168, 192, 251, 343, 377, 

384, 441, 450-1, 453) 492, 498, 53o 

Wharfe Axis, 62, 591 

Williamson, W. C., early zonal work, 8, 

?, 14, 15 

Winchcombe Axis, 67 

Windsor Anticline, 77 

Woolhope-May Hill Axis, 79-83, 395 

Wootton Bassett (Purton) Axis, 67, 80, 

393-5, 403 

Zone, first uses of, 16; refinement of, 

by Oppel, 17; definition 19; chronological 

equivalent (moment or secule), 

21; classes of, 21-3, 34 

Zone-breakers, 33

Aalensis subzone, 165 ff. 

Abbotsbury Iron Ore, 452- 

3, 480 

Acton Turville Beds, 267, 

269-71 

Acuminata Bed, 259, 261, 

280, 282, 324,252 

Acuminata-Sowerbyi Bed, 

279, 295, 300 

Acutum Bed, 179 

Aish, 529-30 

Algovianum subzone, 163 

Allt na Cuile Sandstone, 477 

Alum Shale Series, 182 

A1 wait on Marble, 306 

Ammonite Marble, 120,. 

123 

Ampthill Clay, 376, 409-11, 

417-19 

Anabacia Limestones, 230, 

241 

Anceps zone, 18, 340, 371 

Ancliff Fossil Bed, 272, 274 

Ancolioceras zone, 189 ff., 

206 ff. 

Anglica zone, 376 ff. 

Angulatum zone, ii7ff., 18, 

28 

Antecedens zone, 376 ff., 

380,406,409 

Archceoniscus Bed, 532 

Ardassie Limestones,433-4, 

435 

Ardleyensis Bed, 291 

Argile noire, 376 

Armatum zone, 117, 30; 

Bed,129 

Arngrove Stone, 395, 413x 

4,43i,433 

Astarte obliqua Bed, 230-4, 

236 

Astarte oxoniensis Limestone, 

300 

Astarte supracorallina zone, 

18 

Astarte-Trigonia Bed, 326- 

7, 330-4 

Atherfield Clay, 545 

Athleta zone, 340ff., 18,432 

Aulacostephanus zones, 440 ff. 

Avicula Seam Ironstone, 

161-2 

Aylesbury Limestone, 512- 

13 

INDEX OF STRATA 

(Stage-names not indexed, see Appendix II, p. 617.) 

Bacon Tier, 529-30 

Ball Beds, 432 

Banbury Marble, 134 

Barnack Rag, 213 

Basal Shell Bed (Portland), 

481,488,496,498,503 

Basalt Stone Band, 449 

Base Bed Freestone, 494 

Basement Beds (Portland 

Sand), 504 

Bastard (= Inferior) Oolite, 

4 

Bathonica zone, 248: see 

Bradford Beds 

7, 434-9 

Biarmatas zone, 18, 341 

Bifrons zone, 165 ff. 

Birchi Nodular: Tabular, 

117, 120 

Bird's Nest Rock, 293, 310 

Black Nore Beds, 497; 

Sandstone, 497 

Blackstone, 443, 448-9 

Black Ven Marls, 117 ff. 

Bladonensis Bed, 291 

Blagdeni zone, 189 ff. 

Blea Wyke Beds, 181-2 

Blisworth Clay, 305-7, 311- 

12 

Blockley Clay, 203 

Blue Bed, 485-6 

Blue Ironshot Bed, 172 

| Bourguetia Beds, 189, 200-1 

Boxworth Rock, 410-11 

I Brachiopod Beds, 168, 192 

! Bradford Beds (& Clay), 

I 248-53, 255-6, 262, 267, 

I 269-71,275,286-8,306-7, 

: 321 

; Bradfordensis zone, 189 ff. 

Brauniamtm subzone, 165, 

176-8 

Bridport Sand, 165-7 

Brill Serpulite Bed, 462-3 

Broadford Beds, 143 ff. 

Broken Beds, 518, 527-8 

Bath (or Great) Oolite, 272; Broken Shell Limestone, 

name, 4, 6 

518,524 

Bath Stone, 262, 266-7, : Brora Arenaceous Series, 

272, 277; name, 4, 6 j ; 365-8, 433-4 

Bay lei zone, 440 ff. i ! Brora Argillaceous Series, 

Beetroot Stone, 274 

365, 368-9 

Belemnite Marls, 117 ff.; Brora Brick Clay, 368 

Stone, 117, 119 

Brora Coal, 319-20 

Bencliff Grit, 376-7, 381, 1 Brora Roof Bed, 365, 369- 

384,391,397 

I 7o,339 

Berkshire Oolite Series, 376, Brora Sandstone, 367, 433- 

381-3, 388, 391-2, 398- 

402,403,407-8, 413,426- 

4 

Brora Shales, 368-9 

! Bucklandi zone, 117 ff., 93, 

; 18, 28; Bed, 131 

Buckmani Grit, 189, 201, 

i 205-6, 215,222 

1 Burford Stone, 277, 293, 6 

| Burr Bed or Soft Burr, 

529-30 

! Caillassesd'Hesdigneul,438 

: Calcareous Grit, 4 (see 

; Lower and Upper) 

Calloviense zone, 340 ff. 

Calne Freestone, 390 

Candona ansata zone, 518 ff. 

Capricornu zone, 117 

; Caps (Purbeck), 518, 527-8, 

i 534 

; Carstone, 546-7 

Blue Lias, 117 ff.; name, 4 Castle Hill Beds (= Hack- 

Bluntisham Clay, 409 | ness Rock), 363 

Bone Bed (Rhaetic), 99, 100, i Castor and pollux zone, 

101, 105, 109, III, 112,; 340-1 , 352-5, 368 

113; earliest mammals in, Cave Oolite, 215-17, 93 

101, 105 Cementstone Series (PortjBoueti 

Bed, 250-1, 253, 256 ; land Sand), 489 

Boulder Beds (Kimerid- ' Cephalopod Bed, 165, 171; 

gian), 474-7, 480 Cotswold, 172 ff.

6y6 

STRATAL INDEX 

Chalky Series, 502-3 Cotswold Slates, 278 j 

Cheltenham Beds, 231 Crackment Limestone, 248, 

Chemnitzia Limestone, 424- 260-1, 301 i 

7 

Cream Cheese Beds, 289 j 

Chert Vein, 486,494 Creamy Limestones, 481,, 

Chertv Series, 481 ff. 505-6, 508-9, 511-12 

Chief "Beef Beds, 518, 524 Crendon Building Stone, 

Chirmark Stone, 501, 503-4 _ 5i4 

Chipping Norton Lime- j Crendon Sand, 481, 512 

stone, 248, 267, 283-6, j Crinoid Grit, 221 

298-305, 322-5 

Crushed Ammonoid Shales, | 

Cidaris florigemma zone, 18 1 44o, 447 

Cinder Bed, 518, 525, 531, ! Curf and Chert, 494 

532-3, 538: and see 95 | Cymodoce zone, 440 ff. 

Claxby Ironstone, 546-7 : Cypridea granulosa subzone, ! 

'Clays (Shales) of the Corn- : 518 ff. 

brash', 364, 375, 337, 339 . Cypridea punctata zone, j 

Cleaving or Hard Bed, 504 j 518 ff., 546, 549, 55i 

Cleveland Ironstone Series, 

160-2 

Clunch (= Oxford) Clay, 4 

Clynelish Quarry Sandstone, 

367 

Clypeus Grit, 230, 241-4 

Cockly Bed, 481, 506-8, 

513 

Collyweston Slates, 212 

Commune zone, 165 fF. 

Concava zone, 189 ff. 

Conchoidal Beds (Large 

and Small), 253-4 

Conlaxatum zone, 340-1, 

352-5 

Contorta Shales, 97 ff. 

Coprolite Bed, 546-7 

1 

! Cypridea 

: 518 ff. 

ventrosa zone, 

I Cypris Freestone, 527 j 

! Cypris purbeckensis zone, i 

: 518 ff., 546, 550-1 

I Cypris Shales, 523 

I Cyrena Beds, 503 

1 Cyrena Limestones and; 

Shales, 318 

Dagham Stone, 274 

Davoei zone, 117 ff., 18, 28 

Decipiens zone, 376 

Dew (or Dhu) Bed, 169 

Dicer as arietina zone, 18 

j Digona zone, 18: see Brad- 

; ford Beds 

Coral Bed (Great Oolite), j Dirt Beds, 518, 528-30, 

271-2; (Sharp's Hill Beds), j 534, 537 

300 j Discites zone, 189 ff., 93 

Corallian Beds, 376 ff. j Discus zone, 326 ff. 

Coralline Oolite, 422-6 j Dispansum subzone, 165 ff. 

Coral Rag, 4, 391, 393"4, i Dogger, (Yorks.) 215-17, 

397-400, 403-6, 411» 222-4,180; (Lines.) 214-15 

415-17, 422-6, 436-8 i Double Band, 140-1 

Coral-Shell Bed, 425 i Doulting Stone, 230, 236- 

Corbula and Astarte Beds, I 4i 

309 

• Down Cliff Clay, 165-7, 

Corbula Beds, 518, 524 171-2 

Cordatum zone, 376ff., 413- I Down Cliff Sands, 153-5 

14, 420, 428-9 

Cornbrash, 326 ff.; name, 4 

Coronatum zone, 340-1, 352- 

5 

Corston Beds, 330, 331-2, 

334 

Cotham Beds, 97 ff. 

Cotham Marble, 107, 98, j Dundry 

100 I 242-3 

Cotswold Cephalopod Bed, I 

172 ff., 165, 171 

; Elizabethce zone, 340-1, 

352-5, 368 

Eller Beck Bed, 217, 222-3 

Elongata Bed, 252, 256 

Elsworth Rock, 409, 411- 

13, 416-17 

Emmit Hill Marls, 491 

Estuarine Series (name), 

312. See Lower, Middle, 

and Upper 

Exaratum subzone, 165 ff. 

Exelissa Limestone, 300-1 

Exogyra Bed (Portland 

Sand), 491, 497, 499 

Exogyra Bed (Upper Kimeridge), 

457 

Exogyra nana Beds, 411-13 

Exogyra nana (and prcevirgula) 

385 

Bed, 451, 454, 

Exogyra virgula Clay, 440 

ff. 

Fairford Coral Bed, 274 

Falcifer zone, 165 ff. 

; Faringdon Facies, 400, 403 

Fascally Sandstone, 367-8; 

: Shale, 367-8 

1 Feather Bed, 525 

\ Fibulatum subzone, 165, 

; 176-8 

j Filey Brigg Calcareous Grit, 

: 427 

, Fimbriata-waltoni Beds, 286, 

289-91, 321, 325 

! Fish Bed (Rhaetic), 101,113: 

i see also Bone Bed 

j Forest Marble, 248 ff., 320 

; ff.; name, 4, 268-9,286-8; 

! of commerce, 286-8 

i Forest or Fen (= Oxford) 

i Clay, 4 

! Fossil Bed (Inferior Oolite), 

194,226 

Fossil Forest, 528-9 

Fraasi zone, 340 

Freestone Series (Portland 

Beds), 481 ff. 

! Dumbleton Beds, 175, 179 Freshwater Beds, 309-11 

Dumortierice subzone, 165 , Freshwater Limestones (of 

ff. 

Germany), 549-5 

i Dun Caan Oil Shale, 318 

! Dun Caan Shales, 183-4, 

; 186 

; Duncani zone, 340 ff. 

Freestone, 230, 

Eimbeckhauser Plattenkalk, 

Cotswold Sands, 173-4 ' 550-1, 517 

1 

Freshwater Steps Stone 

Band,449 

Fretting Bed, 504 

Frodingham Ironstone, 136- 

7 

Fuller's Earth, 248 ff., 321- 

4; name, 4; of commerce, 

280, 263; northern limit, 

283-5

Fuller's Earth Rock, 248 ff., 

254, 256-8, 261-7, 280-2; 1 

correlation, 262-6, 281-2; 

name, 4 

Fusca zone, 248 ff., 94 

Garantiana zone, 230 ff., 

93-4 

Giganteus zone, 481 ff. 

Gigas Beds, 550 

STRATAL INDEX 

Hard Lime, 512 

Harford Sands, 189, 201-3, 

206 

Hartwell Clay, 440, 463-7 

Henleyi zone, 117 

Hibaldstow Beds, 214-15, 

217 

Highworth Clay, 398-9, 

400-1 

Highworth Grit, 397~9, 

677 

Kelloway Rock, 341, 363; 

name, 4, 6 

Kelloway's Stone, 4, 6 

Kemble Beds, 248, 267, 

271-3, 286-9, 305-7,321- 

2, 3 2 5_ 

Kerberites zone, 481 ff. 

Kerberus zone, 481 ff. 

Kettleness Beds, 160 

Kimeridge Clay, 440 ff.; 

spelling of, 441; name, 4, 

6 

Kimeridge Coal, 441-3, 

447-9, 4/0 

Kimeridge Grit, 379 

Kimeridge Oil-Shale, 440- 

Glaucolithites zone, 481 ff. • 400-1 

Glaucolithus zone, 481 ff. Hils Clay, 548 

Glauconitic Beds, 481, 507- Hinton Sands, 255, 262, 

9, 5ii, 513-14,517 

267-9,6 

Globata zone, 248 ff. Holton Beds, 405 

Glos Oolite Series, 376, Hook Norton Beds, 286, 

380, 387-8, 389-90, 396, 3°3~4, 312, 322, 324-5, 3, 447-9, 452, 454, 468- 

403, 410-11, 420-2, 436-8 245 

7o, 479 

Glos Sands (Sables de Glos), Hounstout Clay, 440, 446; Kimeridgian Boulder Beds, 

376, 388, 437 

Gorei zone, 481 ff. 

Gravesia zones, 440 ff. 

Gravesiana zone, 440 ff. 

Marls, 440, 446, 497 

474-7 

House Cap, 487 

Kirton Beds, 214-15, 217 

, Hummocky Limestone, 117, Knorri Clay (and Bed), 254, 

120 

252, 260, 280,282 

Great Dirt Bed, 530 Humphriesianum zone, 18, Knotty Bed, 303 

Great Estuarine Series, 316- ; 189 

Koenigi zone, 340 ff. 

20 

Hundleby Clay, 546-8 

Great Oolite, 262 ff.; name, Hydraulic Limestones, 133- 

Lagenalis zone, 326 ff., 18 

4; Series, 248 ff. 

i Lamberti zone, 340 ff. 

5 

Green Ammonite Beds, 117 

Lambfold Hill Grit, 220 

ff.; name, 118, 578 . Ibex zone, n7ff., 18, 28 Laminated Beds, 153 ff. 

Green Bed, 504 

Inconstans Bed, 385 

Landscape Marble, 107 

Green Specked Bed, 514 Inconstant CephalopodBed, Langport Beds, 97 ff. 

Gregarium zone, 340-1, 364 179 . 

Lavernock Shales, 124 

Gres d'Hennequevillc, 376, Inferior Oolite Series, 189 Leptcena Bed, 170, 175, 

388 

, ff.; name, 4, 6, 230-1 179 

Gres de Wirwignes, 438 Insect Beds, 518, 527, 531 Lias, 117 ff.; origin of word, 

Grey Beds, 181 

| Intermedia zone, 326 ff. 4, 12; tectonics, 93. See 

Grey Limestone Series, 217, ; Irius zone, 440 ff. 

Lower, Middle, and Up- 

220-1 

. Ironshot Oolite (Dundry), . per 

Grey Marls (basal Rhaetic), j 196-7,226 

Lilli subzone, 165 ff. 

97 

Ironstone Junction Band, Lincolnshire Limestone, 

; 

Grey Shale Series, 183 308-11 

210-17, 245 

Gristhorpe Plant Bed, 218- 

Lingula Shales, 446 

19, 221, 315 

Jamesoni zone, n7ff., 18, Listy Bed, 486 

Gryphite Grit, 189,201,206 

! 28, 93 ; Limestone, 129 Littlemore Clay Beds, 381, 

Guinea Bed, 109, 135 

\ Jason zone, 340 ff. 

388, 391, 393, 394, 395, 

Jet Rock Series, 182-3, ^5, 406-7, 408, 411 

Hackness Coral Reef, 420, 14 

1 Little Roach, 494 

429 

Jordan Cliff Clays, 343 Littleworth Lydite Clay, 

Hackness Rock, 341, 363 ff. i Jordan Grit, 384 

460,465 

Hadspen Stone, 236-7 Junction Bed, 165-9, 171, Loch Aline Sandstone, 148- 

Hambleton Oolite Series, 174, 74 

; 9 

420, 427-9, 43i 

Jurensis zone, 165 ff., 18 Loch Staffin Beds, 316 

Ham Cliff Grit, 384 

Lomonossovi zone, 440 

Ham Hill Stone, 169 : Kellaways Beds, 341-2, 

Loth River Shales, 476-7 

Hampen Marly Beds, 248, 344-7, 350, 356, 258-65, 

Lower Calcareous Grit, 

267, 275-6, 286, 292-3, 369-72, 374-5 

376-7, 383-4, 388-9, 393, 

321-5; passage to Upper Kellaways Rock, 341 ff.; at 

395-6, 402-3, 408-9, 413- 

Estuarine Series, 302, 310- Kellaways, 346-7 : and see 

14, 419-20, 428-9, 431-5, 

Beds 

i 438-9,443

678 

Lower Estuarine Series, 

(Northants-Lincs.) 207-8, 

214-15, 304; (Yorks) 216- 

19, 222 

Lower Freestone, 189, 197, 

203-4 

Lower Greensand, 546-8, 

47 

Lower Lias, 117 ff. 

Lower Limestone (Corallian), 

427-9 

Lower Limestones (Inferior 

Oolite), 189,197,204-5, 

224 

Lower Lydite Bed, 440, 

456-7, 458, 460, 508 

Lower Trigonia Grit, 189, 

201, 205-6, 214, 215 

Lusa Coral Bed, 146 

Lydite Beds: see Lower- and 

Upper- 

Lyme Regis Beds, 117 ff. 

Macrocephalus zone, 326 ff., 

18 

Maes Knoll Conglomerate, 

237 

Main Building Stones, 503- 

4, 507 

Main Seam Ironstone 

(Cleveland), 161-2 

Malton Oolite, 424 

Mamillated Urchin Series, 

423-4 

Mammal Bed, 518, 526-7 

Maple Ledge Stone Band, 

450 

Margaritatus zone, 153 ff., 

18 

Marice zone, 340 

Marlstone, 153 ff., 168, 

14-15; ironstone, 157-8, 

160-1; name, 4 

Marls-with-Gypsum, 518, 

527,539,551 

Marmorea zone, 248, 253, 

267-9, 286-8 

Marnes de Port-en-Bessin, 

255 

Marnhull and Todber Freestone, 

387-8, 390, 397 

Marston Marble, 123 

Martelli zone, 376 ff., 381, 

397, 400, 409, 4 T 3, 4 l6 , 

434, 438-9 

Massive Bed (Portland 

Sand), 445-6, 491-2, 497, 

499 

Massive Beds (Inf. Oolite), 

230,232-3 

S T R A T A L INDEX 

Metacypris forbesii subzone, 1 Oolithe blanche de Lang- 

518 ff., 546, 549, 551 

Micaceous Beds, 153 ff. 

Microzoa and Sponge Beds, 

230-3 

Middle Calcareous Grit, 

426-7, 428 

Middle Estuarine Series, 

217-21 

Middle Lias, 153 ff. 

Midford Sands, 171-3 

Milborne Beds, 257-8 

rune, 253 

! Oolithe d'Heshin-l'Abbe, 

437 

Oolithe de Trouville, 438 

Opaliniforme subzone, 165 

ff. 

Opalinum zone, 165 ff. 

Ornatum zone, 340-1, 354 

Ornithella Marl, 274, 292, 

321 

Osmington Oolite Series, 

' Millepore Series, 217, 221-; 376-7, 3S0-1, 384, 386-8, 

1 2, 93 : 390-1, 393-4, 396, 397-9, 

! Minchinhampton Freestone,! 403-7, 416-17, 422-6, 

| 266-7, 277 ; 436-8 

Moorei subzone, 165 ff. ! Osses Ed, 511 

Moor Grit, 312-13 Ostracod Shales, 518, 523, 

. Munder Marls, 549-53 ! 549 

Murchisonae zone, 189 ff., ! Ostrea acuminata Bed, 259, 

! 18 

261, 280, 282, 324, 252 

Mutabilis zone, 440 ff. Ostrea 

317-18 

hebridica Beds, 

I Natica Band, 401 

Ostrea liassica Beds, 117 ff. 

j Neaeran Beds, 286,297-301, Ostrea sowerbyi Beds, 252, 

310 

268, 269, 275-6, 292-3, 

Nerinea Beds, 249, 274, 300, 305-7, 309-10, 316- 

291-2, 300 

18,322,325 

Niortensis zone, 230, 233, Oxford Clay, 341 ff.; name, 

235-6,246 

4, 7 

i Nist Bed, 486 

Oxford Oolite, 7, 405 

j Nodiferus zone, 440, 461 Oxonica zone, 248 ff. 

Nodular Coralline Rubble, Oxynotum zone, 117 ff., 18, 

381,404-5 

28,31 

j Northampton Ironstone 

j Series, 207-10, 212-15 i Pabba Shales, 143 ff. 

! Northampton Sands, 207- Pachyrisma Bed, 275 

! 10, 212-15 

Pallasianus zone, 440 

North Grimston Cement- Pallasioides zone, 440 ff. 

stone, 420-2 

Parallel Bands, 489-90, 499 

Notgrove Freestone, 189, Parkinsoni zone, 18, 234 

201, 206 

Passage Beds (Corallian), 

Nothe Clay, 376-7, 381-4,: 427-9 

387, 39I, 393, 439 Paving Bed, 194 

Nothe Grit, 376, 383-4, Pavlovia zones, 440 ff. 

385, 387 

Pea Grit Series, 189, 197, 

Nuculana ovum Clays, 177- 204-6 

Peak Shales, 182 

I Pebble Bed (Corallian), 391- 

Oakley Clay (Beds), 409, | 2, 393, 394, 396, 398-9, 

411-12 402,408,412,429,94 

Oaktree(=Kimeridge) Clay, ' Pecten Bed Ironstone (Lower 

4, 8 I Lias), 136 

I Ob Breakish Coral Bed, 146 j Pecten Seam Ironstone 

! Obovata zone, 326 ff. ! (Mid. Lias), 161-2 

j Obtusum zone, 117 ff., 18,: Pectinatus zone, 440 ff. 

28; Nodule Bed, 129-31 Pendle (Corallian), 404 

I Okusensis zone, 481 ff. Pentacrinus tuber culatus 

! Oolite Marl, 189, 197, 203, zone, 18 

! 205 

Pentacrinus zone, 117

Perarmatum zone, 376, 427 

Perna Bed (Lower Greensand), 

545 

Perna Bed (Portland Stone), 

485-6 

Perna Bed (Sharp's Hill 

Beds), 300-1 

Perrott Stone, 169 

Pettos zone, 134 

Phillipsiana Beds, 189,200- 

1 

Pierre de Taille de Ranville, 

270 

Pink Bed, 172 

Pinney Bed, 504 

Planking (Great Oolite), 

275> 277, 303; (Inferior 

Oolite), 305 

Planorbis zone, 117 ff., 18, 

28 

Pleuromya Limestone, 141 

Polyzoa Marl, 256 

Pon or Pond Freestone, 

486, 494 

Port-an-Righ Ironstones, 

434; Sandstones, 434 

Portland Beds, 481 ff. 

Portland Clay, 496-7 

Portland Sands, 445-6,481- 

2, 489 ff.; name, 6-7 

Portland Stone, 481,483 ff.; 

of Portland, 493-4; name, 

4,6 

Portree Shales, 185-7 

Posidonia bronni zone, 18 

Prcecordatum zone, 340 ff., 

412, 418, 432, 434-5 j 

439 

Pr^-planorbis Beds, n7ff. 

Preston Grit, 383 

Pronice zone, 340, 349, 355, 

368 

Provirgatites zone, 481 ff. 

Pseudogigas zone, 481, 507 

Pseudomutabilis zone, 440 ff. 

Pseudovatum subzone, 182 

Pterocera oceani zone, 18 

Punfield Beds, 545 

Purbeck Beds, 518 ff.; name, 

4; thickness, 47; junction 

with Wealden, 542-5; in 

Germany, &c., 549-55 

Purbeck Building Stones, 

518, 520-1, 524-5; name, 

4,6 

Purbeck Marble, 518, 521, 

523,538 

Purbeck-Portland Stone, 

483 

Pusey Flags, 397-8 

STRATAL INDEX 

Raasay Ironstone, 185-7 

Radcliff Grit, 384 

Rag Beds (Great Oolite), 

272-3, 277, 280 

Ragstone Beds (Great 

: Oolite), 273, 279, 280 

Ragstone Beds (Portland 

Stone), 502-3 ! 

Ragstones (Inferior Oolite), j 

198, 200-2, 206 

Raricostatum zone, 117 ff., 

18, 28, 30 

Rasenia zones, 440 ff. 

Red Band (Lower Lias), 

• 118 

Red Bed (Inferior Oolite), 

190-1, 233 

Red Beds (Corallian), 380 

Red Beds (Oxford Clay),; 

343 

Red Nodule Beds, 343 

Reginaldi zone, 340 ff. 

1 Rehmanni zone, 340 

679 

Sandsfoot Clay, 376, 380, 

384-6,411,417,437-8 

Sandsfoot Grit, 376, 379, 

385-6, 389, 437-8 

Sandy Series (Middle Lias), 

140, 160-2 

Sandy Series (Portland). 

489 

Saurian and Fish Bed, 170, 

175, 179, 187 

Sauzei zone, 189 ff., 18 

Scalpa Sandstone, 162-3, 

144 

Scarborough Beds, 217, 

220-1, 245 

Scarburgense zone, 340-1 

Schloenbachi zone, 230 ff. 

Scissum zone (and Beds), 

iSgff., 206ff., 166, 168,93 

Scroff, The, 250-1, 255, 

260, 301 

Scythicus zone, 445, 481, 

49i,5o7, 681 

! Renggeri zone, 340 ff. ; 

! Rhaetic Beds, 97 ff., 92-3 

Rhaxella Chert, 395, 414, 

I 431 i 

! Rhynchonella [Goniorhyn- j 

j chia] boueti Bed, 250-1,1 

j 253,256 ^ | 

| Rhynchonella [Kallirhyn- ! 

j chia] concinna Beds: see \ 

| Hampen Marly Beds 

i Rhynchonella [Rhactorhyn- • 

' chia] inconstans Clay, 385, 

i 44°> 451 ; Rhynchonella ringens Beds, 

j 194-5 . | 

i Rhynchonella subvariabilis \ 

Marls, 446 

1 

Semicostatum zone, 117 ff., 

28, 93 

Serpulite, 95, 549"53 

Sevenhampton Marl, 279 

Sevenhampton Rhynchonella 

Bed, 279, 294, 300 

'Shales (Clays) of the Cornbrash', 

337, 339, 364, 375 

Shales-with-Beef, ii7ff. 

Sharp's Hill Beds, 286, 

297-301 

Shell-cum-Pebble Bed, 396, 

403-5, 407-8 

Sherborne Building Stone, 

230, 234, 236 

Shirbuirnice zone, 189 ff. 

Shotover Grit Sands, 440, 

! Ringstead Coral Bed, 376, ; 455-7, 460-1, 463-6, 508; 

379,385-6,389,451-2,454! Fine Sands, 461 

; Ringsteadia zone, 376 ff. j Shotover Sands or Iron- 

j Ringstead Waxy Clay, 376, ; sands, 535, 544 

379, 385-6, 389 ' Shrimp Bed, 485, 488, 494, 

Roach, 493-4,496,498,502, 498,511 

503, 505, 507 

Siddingtonensis zone, 326 

Rope Lake Head Stone Silver Bed, 211, 213, 214 

Band, 449 

Skull Cap, 530 

Rotunda Nodules, 440,446- Slant Bed, 504 

7; zone, 440 ff. 

Slatt, 529-30 

Roundhill Clay, 283, 285 Snettisham Clay, 546-7 

Rubbly Beds (Inf. Oolite), Snowshill Clay, 189, 201-3, 

230, 234, 241 

Rubbly Limestones (Portland 

Beds), 481, 509, 513 

206 

Southerndown 

126-7 

Series, 

Saccocoma subzone, 448, 

! 452, 454, 468, 479 

Sandringham Sands, 567 

Spangle, 485-6, 487 

Speeton Clay, 546-8 

Spilsby Sandstone, 546-8, 

552

68o 

Spinatum zone, 153 ff., 18 

Spindle Thorn Limestone, 

220 

Spinosum zone, 340, 354-5 

Spiriferina Bed, 131 

Staithes Beds, 160 

St. Alban's Head Marls, 

490-1,507 

Starfish Bed, i53~5 

Steeple Ashton Coral Reef, 

389-90, 417, 423> 438 

St. Ives Rock, 412-13 

Stonebarrow Beds, 117 ff. 

Stonesfield Slate, 248, 263- 

7, 277-9, 294-7, 308-9, 

311, 323-5; of commerce, 

278, 295-6; mammals in, 

296-7; name, 4, 7 

Striatulum Shales, 181-2 

Striatulum subzone, 165 ff. 

Struckmanni subzone, 165 ff. 

Stutchburii zone, 340-1, 

349, 350, 354, 368 

Subcarinata subzone, 165, 

176-8 

Subcontractus zone, 248 ff.; 

T. subcontractus in Great 

Oolite, 273, 275, 292 

Subplanites zones, 440, 444, 

447-9, 455, 469, 480 

Sully Beds, 97 ff. 

Sun Bed, 106, 111, 112 

Sussex Marble, 542 

Sutton Stone, 126-7 

Swerford Beds, 286, 303-4, 

322,324-5 

Swindon Clay, 440, 456, 

458, 460, 463-6, 508 

Swindon Sand and Stone, 

481, 506, 508,512 

Table Ledge Stone Band, 

117, 121 

Tatei zone, 117 ff. 

Taynton Stone, 248, 267, 

273, 276-80, 286, 293-4, 

311, 324-5 

Tea Green Marls, 98 ff. 

Tealby Clay, 546-7; Limestone, 

546-7 

Tenuicostatum zone (Oxford 

Clay), 340, 348 

Tenuicostatum zone (Upper 

Lias), 165 ff. 

Tetworth Clay, 409 

Thame Sands, 463, 466-7, 

508 

The Flats Stone Band, 45 

Thorncombe Sands, 153- 

STRATAL INDEX 

| Thornford Beds, 257-8 

I Three Tiers, 153-5, 118 

1 Tidmoor Point Beds, 344 

Tilestone, 189, 201-3, 206 

Titan zone, 481 ff. 

Titanites Bed, 485-6, 488, 

! 494,498, 518;zone, 481 ff. 

' Top Beds (Inferior Oolite), 

234 

Torulosus zone, 18 

Transition (Acutum) Bed, 

! 179 

i Transversarius zone, 376, 

! 400 

| Trigonia clavellata Beds, 

; 376-7, 380, 384, 386-8, 

| 390, 396-7, 4IO-II, 416- 

; 17,423,437-8 

• Trigonia gibbosa zone, 18 

Trigonia hudlestoni Beds (and 

Limestones), 376,383, 387, 

399-401,408,413,426-7, 

i 438-9 

Trigonia navis zone, 18 

Trigonia signata Bed, 303, 

322 

Trough Bed, 504 

Truellei zone, 230 ff., 259, 

93 

Tuberculatus zone, 18 

Turneri Clay, 131 

Two-Foot Seam Ironstone, 

161 

Upper Inferior Oolite, 

230 ff. 

Upper Lias, 165 ff. 

Upper Limestone, 422-6, 

428 

Upper Lydite Bed, 455-6, 

460, 463-7, 481, 504-5, 

507-8, 510, 513-15, 517 

Upper Oolite ( = Great 

Oolite), 4 

Upper Trigonia Grit, 230, 

238, 243-4 

Upware Coral Reef, 409, 

415-17, 423 

Urchin Marls, 398-9, 400i,439 

Variable Beds, 207-8, 214- 

15, 305 

Variabilis subzone, 165 ff. 

| Vernoni zone, 340-1, 362, 

433, 434 

Vertumnus zone, 340-1, 364 

Virgatites zones, 440, 445, 

448-9 

Virgatosphinctoides zones, 

440 ff. 

Viviparus Clays, 518, 523, 

538 

Viviparus Marl, 298-300 

Viviparus scoticus Limestones, 

318,316 

Umber Bed, 254 

Wartce zone, 376 ff., 380, 

i 389, 410-n 

Under Beds (of Chilmark | Watchet Beds, 97 ff. 

Stone), 504 

j Water stone, 514 

Under Freestone, 487-8 | Watton Cliff Brachiopod 

Under (= Inferior) Oolite, ! Beds, 254, 250-1 

4 

| Wealden Beds, 47, 541-9, 

Under Picking Cap, 487 552-5 

Unio Beds, 518, 523, 532 I Wear Cliff Beds, 117 ff. 

; Uppat Cardioceras Bed, I Weatherstones or Shelly 

! 433-4, 435 

Beds, 275, 277 

i Upper Building Stones, 502 ; Westbrook Coral Reef, 392 

1 Upper Calcareous Grit, 376, Westbury Beds, 97 ff. 

378, 385-7, 389, 395, 396, Westbury Iron Ore, 376, 

1 

403, 411, 420-2, 425, 379, 385-6, 389, 395, 396, 

: 436-7, 458 

: 437 

Upper Coral Bed, 230, ! West Weare Sandstones, 

242-4 

! 497,502,507 

Upper Coral Rag, 379 ' Wheatleyensis Nodules, 440, 

Upper Estuarine Clay, 267, 461-2; zone, 440 ff. 

283-4, 297-301 

j Wheatley Limestones, 393- 

Upper Estuarine Lime- 4,403-6,411,425,7 

: stone, 310 

Whit Bed, 494 

Upper Estuarine Series, Whitbian, 165 ff. 

i 305, 308-16; name, 312 White Cementstone, 491 

i Upper Freestone, 189,197- W 

1 8, 203, 206 

Thite Ironshot (Dundry), 

196-7

STRATAL INDEX 681 

White Lias, 97 ff.; name, 4 ; Whitwell Oolite, 216-17, j Yellow Beds, 181 

White Limestone, 248, 267, j 221-2, 93 ! Yellow Conglomerate, 191-2 

272, 274-5, 286, 291-2, | Wild Bed, 192, 226 | Yellow Ledge Stone Band, 

305-8,311-12,321-5 Witchellia Grit, 189,! 440,449-50,468 

White Roach, 524 j 201 Yeovilian, 165 ff. 

White Sands, 286, 303-5, j Witchellice zone, 189 ff. 

325 "j Witchett, 511-12 

White Septarian Band, 449 : Worminghall Rock, 414 

White Sponge Limestone, | Wychwood Beds, 248, 252- j 280, 301 

Yeovil Sands, 168-9, I 7 I " 2 

Zigzag Bed, 250-1, 258-61, 

231-2 1 3, 267-9, 286-8, 306 I Zigzag zone, 249 ff., 94 

CORRIGENDA 

Pp. 390, 400. Isognomon [= Perna] mytiloides Lamk et auct. The name will have to 

be changed owing to its having been preoccupied for an Inferior Oolite species by 

Hermann (1781). W^here mentioned the species is probably I. subplana (fitallon). 

Pp. 468-70. The Astarte supracorallina of Blake, Roberts, Woodward, and others, 

is not A. supracorallina d'Orbigny but A. my sis d'Orbigny, which is probably 

synonymous with A. externa Phillips. Both these matters will be dealt with in 

forthcoming instalments of 'A Monograph of the British Corallian Lamellibranchia'. 

P. 613. Explanation of Plate XL, fig. 3. Provirgatites scythicus was first named and 

figured by Vischniakoff in 1882 ('Descr. des Planulati (Perisphinctes) jurass. de 

Moscou', pi. iii, figs. 1, 2). The types came from Mniovniki near Moscow. Michalski's 

specimens are at least chorotypes.

Untitled

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?