EN Tee ge see ng Syeasasaoe aes De oR SENSES SCHED X Sa Cea Hosaka Seeks 405, RRR ESLLOSS a as Pees Cele, ee ee, Oe ibs ies eeacrteet Nee (hi Ui A See S iS NIE Rea teaiages sees ott if eases ticsetatenttnee eS SSaeeasesaesucatenysesateaisee 3 eee es ates , Ry * rates ee bs Siergcs Sait i oy ie = RS ee eRe A etg Bie 5 eee a5 ae Ses Raitt CCST ee RES od is Ses Maes ScpESA SUC) Helene RedetaNccnteeri recess Raed See Seeietans are Reread RC eeu tecdt sag Se Feoese te eeec scotia saad sia MENS AER TC ts CH eiMated USAR eR HeS Aen ECT eopeesrn thant hy SSN OM ¢ RSI MORI HeSE epg Ses EC Cee, Pe eeneesebeorhttanorhe hy be ek bah DL PePL Pye Pernhh hahahah trae be gt Lorbtyr othe brochiahshy Pe tab dy Ba SdSa od Se Sea SCS Hed Op Bee ean sere sees aia a Sate aE Ite RICCI SAN asain es Sth oe “ aE eae to bpopprpynebrer estab Nase aCe Resetesannien Net AMICI MIRON LNS eS eSe SRLS FEN Ca ea bata tea tate ssesedale ehh c$ Safa SCSED tel otese eee merrypaPaet eR aaah Suites SEAS Seale Sega ee ito Hesasiseneetn aan! CM) Reisseuteec esate’ *} peotneyhererrrre Henne yp Pe hy eee ie aaah egad COOSA 4, He heeasese tessa Ses cere Sa eate hates aaeixee esa eens GCS i % Ute i Ke (Sas hata Sahat ifehegete Seda eane esere geeks < erie seteeesesaeenc thease sas S aie ete », i sede ips ae ace ee egeepeey Perea ea tase de fate eso ae eet Me tt t < UAC Gh ay 4 Keser ece Ria staantaaatanatt Chaka Faseneiete tea sa ese reg tere Hana esed es Caen Seeetsenreentiasoeienr teh Siti eiisteaa tear gat : eesetes See Sata ‘ cS Auerey is OC aSe' G i rsPatnrs preeatae Papraree pret epererstenry eet eae ate > seehd eich he! Cohetatat tate frtotate te eps Lge F Jase bee: eee Sit ahat hate sais FORA et Sok OAM OK A Sefese sae Sescie'e a Cad 4 CL Ppa ete set ictsta lef a RR et hak hee, eoarea ease rietatcs i“ Pees Me tetrs UCT pete aan eiai 2 a ¥ f > e is i 5 rs 2 7 et iS osaeeds ead ed esos eee soaredaee Gi ri : etek oy hah, tases Cad Head od Ko Sekt id Aa TOE RAS gs aes sete ‘ aeseaes Sasa t date etn eM Ge hee esnticeite i ee i 54 Sehehc at ; ae at A fie es site es J ‘ 606% Seghe 7, és eS 7 ¢ C rt eo) o SiS tSaSeie$ Seti cteeeeet tec tatek Re Heh OL he ha ahesehacectesecaseede Sk Saha esecesess Ce atten tet (ACE A Aaa ; ee MMA AeA eh AC Chace eSegs eM Se KTS stetetattetet tre Eee alae dot id eee dod odd Sd rtae Sees seice Sasa eee ech Lett Catala Sele Coed Sree iets eee ethers Msc SaSa Sa Sahat Se Sd ed nda ited ae Aso t Maha h hk gg be iSekehesecetesesataicie ‘S eieieeiieseaetceeneotice (ieee Cantata teeice Mie Ais Hse Selah aia ieSales SSAA ene geet eS Msehesaseseseietes cies cea ate at tN RC eee dlc atta eter eh Csstgiehs (hess shah nes rf S66 ‘ 4 S < Sele ohasa Sata hates tit: ASA ad ed eh Cat ts iSies Seat haheet ed “4 Neceeataet , esata ; as eels ee totaat fet H See es 6 4 Meh Sei ahcte les ates Seieht Sef wine o ase fis ies iS Sd +, 7 ' 4 MMA OE he WE hse et Reta aa giclee Che POPPE VL DE FLY PER aCe PoP hay) ( eens alee sohettans ie OO RRMA ESA eohte is sade (Seth eSdide died sched AMA aa ECHR eH CEE ALG CCL dC Streak 4 eset Saha odie 4 ss CSAS a seh ake “é AERC e (Sede ed SAS AAS e Sead aie (55 5 eee ass Ms Nea cs ” Saat titty dS CK ASL 4 Site rstets Ss rot ‘ ath AOA ok . Scot ie ye ee te ies Ae Saate < 7‘ ea a at vy ANG Sie ee ANG See eees ‘ 6 hehe Cie G (M4 4 , s MSA AAA AA AAS Leet Nhheeg anche died ‘“ 7, CMCSA R ANd edd AULA Ahk AEE AK he AM MAAK ALAES oy Hea Seen — 6g Ae CG ic Maeda Cte CAA AA AA Om CAs 7 LRA SA ASA [Aaa Sees 4g hee SU : ‘ the ices hese Kade ee eh ase ees ah Asher : CAA BK a a SECC ¥ A “ CEE é “ f ehhh Aeneas Geka eh ea Mahe eh eM eh A deh ahh heh eas z 4 . i Z iss Metts actihe as aed ase 4 weeta Kf tt ae hee Seo aces S AeA CeA OC Mae ht hh ha Maha i } i Ke icant WORST POV O Mo VY THOTT PAT PPPOE! eicetece detects Aaa EAA Sane Aneel letersi Bite POSSE ENOL ROMTSR sRsrtted ee daa cau nete tenance z cs : Pe Lae CAEL LEL Bae Se LP AI OCR: ELLOH CELE “4 ay i Sosa ( RRA Hy MS AAS OE os, a) DENTS (FES Cornell Aniversity Library BOUGHT WITH THE INCOME FROM THE SAGE ENDOWMENT FUND THE GIFT OF Henry W. Sage 1891 AUS.G50 aise Cm! eRe ENGINEERING LIBRARY. Date Due PRINTED IN|U. 3, a, Cornell University Libra The geology of the Isle of Wight, MEMOIRS OF THE GEOLOGICAL SURVEY. ENGLAND AND WALES. THE GEOLOGY OF THE ISLE OF WIGHT, BY HENRY WILLIAM BRISTOW, F-.RS., F.G.S. SECOND EDITION, REVISED AND ENLARGED, BY CLEMENT REID, F.LS., E.G.S., AND AUBREY STRAHAN, M.A., E.G.S. RAR RARARARAARAA ARN PUBLISHED BY ORDER OF THE LORDS COMMISSIONERS OF HER MAJESTY’S TREASURY. ARR AAR RRARAAR A AAR RA LONDON: PRINTED FOR HER MAJESTY’S STATIONERY OFFICE, BY EYRE AND SPOTTISWOODE, PRINTERS TO THE QUEEN’S MOST EXCELLENT MAJESTY. And to be purchased, either directly or through any Bookseller, from EYRE anp SPOTTISWOODE, East Harpine STREET, FLEET STREET, E.C., or ADAM anp CHARLES BLACK, 6, NorTH BRIDGE, EDINBURGH; or HODGES, FIGGIS, & Co., 104, GRAFTON STREET, DUBLIN. 1889. Price Eight Shillings and Sixpence. Qk WeRtL + ee | on N.\\ 3050 PREFACE. THE onward progress of geological science during more than a quarter of a century since the first edition of the present Memoir appeared has not left the Isle of Wight unaffected. The geological formations on which the beauty of that fair Island so largely depends have been studied in great detail in all parts of the South of England, as well as in foreign countries. The coast- sections of the Isle of Wight have even become subjects of discus- sion and controversy. When, therefore, the first edition of this Memoir was nearly exhausted, and it became necessary to under- take the preparation of a second edition, I felt that no satisfactory progress could be made in this task until the Map of the Island had been first revised and brought abreast of the present con- dition of Geology. The publication of the large Ordnance Survey Maps on the scale of six inches to a mile supplied for such a. revision a far more accurate and convenient basis than was available at the time when the Island was originally mapped by the Geological Survey. Accordingly, Mr. Bristow, the Senior Director, to whom science is mainly indebted for the first Survey Map of the Isle of Wight, and for the Memoir descriptive of the structure of the Island, undertook the serious labour of superintending the pre- paration of new editions, both of Map and Memoir. In the following Prefatory Note supplied by him he has stated how this work has been carried on under his general supervision. The revision of the Map became in fact a re-survey of the Island, as all the lines were retraced on the ground. It 1s, however, due to Mr. Bristow to add that the main geological lines remain- nearly as he mapped them more than 30 years ago. In the preparation of the present edition of the Memoir so many and important have been the changes required that the work might not unfairly be described as a new one. The revision alike of Map and Memoir has been made under Mr. Bristow’s direction and with his co-operation, by two of the officers of the Survey, Mr. C. Reid, who took the ‘Tertiary area, and Mr. A. Strahan, who had assigned to him the Secondary Rocks. I have also myself personally visited the Island with Messrs. Reid and Strahan, and read over on the ground the proofs of the following chapters. I will here briefly mention some of the more important alterations and additions. In discussing the relations of the Wealden to the Upper Neocomian Rocks it is shown that these two groups are separated by a sharply-defined lithological demarcation, accompanied by a paleontological break. E 56786. Wt. 17374 a oO = iv In re-mapping the Lower Greensand Mr. Strahan has taken advantage of certain broad lithological characters, which being traceable across the Island, permitted of a convenient subdivision of that formation into groups whose respective limits could be shown on the Map. This subdivision, for which a new scheme of colouring has been adopted, is only intended for the Isle of Wight, where it is of considerable local service. Mr. Strahan found that an upper subgroup of the Lower Greensand, correspond- ing to the Folkestone Beds, existed on the Island, capable of sub- division into an upper ferruginous and slightly conglomeratic rock, the Carstone, which passes up into the Gault, and a lower sand- rock resembling in lithological characters the Folkestone Beds, and passing downwards into ferruginous sands. Another subgroup, exhibiting both the lithological and paleontological features of the Sandgate Beds, has been placed with these underlying sands (the Hythe Beds) under the name of the Ferruginous Sands. The position and extent of the Atherfield Clay remain nearly as in the first edition of the Map. A. few fossils have been added to the small fauna hitherto yielded by the Gault. A line has been engraved on the Map to mark the position of the bold topographical feature formed by the Chert beds of the Upper Greensand in the central parts of the Tsland. The subdivisions of the Chalk which can be traced on the ground have now been inserted on the Map. The Chalk-rock is so shown, but the Melbourn-rock, though frequently recog- nised in place, is not represented on the Map for want of space, In the preparation of the following Chapters it has been found necessary entirely to re-measure the cliff sections of the Secondary Rocks. This has been done in Compton Bay from the Upper Greensand downwards, in Atherfield Bay from the Chalk-marl downwards, and in Sandown Bay from the Chalk-rock down- wards. The total thickness of strata measured at the last-named locality was 1,218 feet. The results of this detailed re-exami- nation are shown graphically in Plate II, which represents the coast-section from Compton Bay to Blackgang, and in Plate III., which contains a series of comparative Vertical Sections showing the varying thickness of the Secondary formations in different parts of the Island and on the adjacent coast of Dorsetshire. In revising the Tertiary area of the Island, Mr. Reid found that only slight changes were required in the Eocene lines of the Map. In the Sections and Memoir he has somewhat modified the boundaries of the Bracklesham and Barton Beds in econ- formity with the recent researches of the Rev. Osmond Fisher and Mr. Keeping. The so-called “ Upper Bagshot Sands” of the Isle of Wight are not improbably considerably higher than the division of that name in the actual Bagshot district. Hence until the position of the glass-sands of the Island has been pistes lag z has been thought desirable not to speak of these deposits as “ er Bagshot,” but to rever name of “ Hssdon Hill Bande es Vv The classification of the Kocene formations into Upper, Middle, and Lower, adopted in the first edition of the Memoir, has been modified. ‘The so-called “ fluvio-marine beds” of the Isle of Wight are now classed as Oligocene. The most important alteration of the Map of the Tertiary part of the Island has been in the tract occupied by the Hamstead (Hempstead) Beds. These strata have been detected by Mr. Reid by means cf a boring apparatus over a large area, so that instead of covering a space of only two or three square miles, they really spread over half of the Tertiary district of the Island. They also prove to be of considerably greater thickness than has been supposed, their actual thickness being 260 feet instead of 170 feet. The sections in the Tertiary districts have been re- measured where it was thought desirable. The Chapters on the Tertiary rocks in the present Memoir have been largely extended and in great part re-written. In the recent re-survey of the Isle of Wight the superficial deposits have been mapped out in detail. They have been arranged in four groups which are based, as far as possible, on chronological order. Excluding the angular flint-gravel of the Chalk Downs, the age of which is doubtful, the oldest group, that of the Plateau Gravels, is shown to be probably as old as, and perhaps contemporaneous with, some of the Glacial deposits of the Midlands. But no conclusive evidence has been obtained in the Isle of Wight of the co-operation of coast-ice or land-ice in the formation of these deposits. The later groups (Valley Gravels and Alluvia) contain the records of successive stages in the excavation of the present system of valleys. This Geet of geological history possesses a special interest and value from the insular position of the Isle of Wight and the changes that have resulted from the cutting back of the coast-line by the sea. The drainage system of the Island, like that of the South of England generally, bas been determiaed by the great lines of anticlinal and synclinal folds into which the Secondary and Tertiary strata have been thrown. Hach main anticline became a line of watershed, but in the subsequent gradual denudation of the general surface of the land the forms and elevations of the topography have resulted, not from these underground movements, but from the relative durability of the rocks. The areas of maximum elevation at the present day are not those where the greatest amount of upheaval took place in past. time. Mr. Strahan’s survey of the superficial deposits in the south of the Isle of Wight affords a glimpse of an older and different topography before the Chalk Downs of that region had been reduced to their present limited area. An extensive sheet of river-gravel in the south-west of the Island marks the course of what must at one time have been a considerable stream, taking its rise among the Southern Downs which then stretched southwards into the English Channel. As Mr. Codrington has suggested, this stream flowed westwards and northwards by Freshwater to v1 Yarmouth. But by the gradual encroachment of the sea its drainage area has been greatly reduced, and at last its valley has actually been reached and cut across by the waves, so that the stream there enters the sea, and the lower part of the valley is left almost dry. One of the following chapters has been devoted to a description of the nature and position of the various anticlinal and synclinal folds which play so Jarge a part in the geological structure, not only of the Isle of Wight but of the whole of the south-eastern mainland. From the evidence obtainable in the Island we know that these plications of the rocks were produced at some time subsequent to the deposition of the Oligocene strata. Elsewhere we obtain proofs that they were completed before the Pliocene period. The limits of their geological date are thus fixed. The Appendices include a number of well-sections and borings collected and arranged by Mr. Reid. The fossil lists formerly dispersed through the Memoir have been thrown together into one tabular statement which has been prepared by Messrs. Reid and Strahan with the assistance of Mr, G. Sharman and Mr. E. T. Newton, Palzontologists of the Geological Survey. A geological biblicgraphy, compiled by Mr. Bristow, has been added to the Memoir. ARCH. GEIKIE, Director-General. Geological Survey Office, London, April 1889. [Since this preface was written, and while these pages are passing through the press, Mr. Bristow has been removed from us by death. We hoped that he would have lived to see the final publication of this Memoir, in the preparation of which he took so keen an interest. The correction of his “ Notice” formed his last piece of scientific work, and in returning it to me only a few weeks before the illness from which he never recovered, he expressed with characteristic courtesy his approval of all that had been done to make this new edition a fitting termination to the labours of his long career in the Geological Survey. We cherish his memory as a loyal and helpful friend and a distinguished colleague. A. G. June 24th, 1889. ] vii NOTICE (By H. W. Bristow, F.R.S.) THE original survey of the Isle of Wight on the one-inch scale was commenced under the personal superintendence of Sir Henry T. De la Beche in the year 1848, and was carried on at intervals between that year and 1856 by the late Professor Edward Forbes and myself, Mr. W. T. Aveline at the same time completing a portion of the Secondary area between Chale and Dunnose, the whole being under the direction of Professor A. C. Ramsay. During part of the time that the Island was being surveyed assistance was rendered by the late Mr. R. A. C. Godwin-Austen, Mr. Henry Keeping (now of the Woodwardian Museum, Cambridge), and by the Fossil Collectors, Richard Gibbs and John Cotton. A re-survey of the Island on the six-inch scale instituted by the present Director-General was begun in November 1886, and was completed by the end of the year 1887, the northern or Tertiary half of the Island being mapped by Mr. C. Reid, and the southern or Secondary half by Mr. A. Strahan. This re-survey, reduced to the new one-inch Ordnance Map, was published in 1888. Clean copies of the six-inch Maps have been deposited in the Geological Survey Office for reference, and a duplicate set of these sheets, mounted as a wall-map, was exhibited at the International Geological Congress in 1888, and is now suspended in the Museum of Practical Geology. The first edition of the present Memoir was published in 1862. It was written by myself by desire of the late Sir Roderick J. Murchison, then Director-General, use bemg made, when neces- sary, of the posthumous Memoir on the Fluvio-marine Formation of the Isle of Wight by Professor E. Forbes, in which some of the notes J had made had already appeared. In the preparation of the present edition of the Memoir the authorship of the revision has followed the same general distribution as in the case of the mapping. The account of the Secondary rocks has been revised and enlarged by Mr. Strahan, who, besides examining these rocks in the Isle of Wight, continued the mapping of their subdivisions into the neighbouring coast of Dorsetshire. The com- parisons with the Geology of the mainland made in the following account of the Secondary rocks are thus entirely his. The chapters on the Tertiary rocks have been revised and much enlarged by Mr. Reid. The most important change which he has been able to make in the Map, the great extension he has given to the Hamstead Beds, has been rendered possible by the application of a boring apparatus, whereby no fewer than 358 borings, ranging from 10 to 33 feet in depth, were made in the Tertiary area of the Island. vill The lists of fossils have undergone a thorough revision by Messrs. G. Sharman and E. T. Newton, who have also named the additional specimens collected during the progress of the re- survey. Professor T, Rupert Jones undertook the determination of the Ostracoda, revised the lists of these crustacea, and furnished Table V., which gives a synoptical view of their distribution. We are also indebted to Mr. J. Starkie Gardner for the account of the Flora of the Bagshot Beds of Alum Bay, and to Mr. Car- ruthers for looking over the lists (In MS.) of the plants of the Secondary rocks. Mr. W. Hill kindly undertook the examination under the microscope of nodules from the Upper Chalk of White- chff. Advantage was taken also of the intimate knowledge of the Geology of the Isle of Wight possessed by Mr. Henry Keeping to obtain his assistance in revising some of the detailed sections of the Tertiary strata. H. W. Bristow. London, March 30, 1889. TABLE OF COS EEN ED: Prerace, BY THE Direcror-GENERAL - Notice, sy H. W. Bristow, F.RB.S. - - - CHAPTER I. InrTRoDUCTION AND TaBLe or STRATA - CHAPTER [I. WEALDEN BEDS:— INTRODUCTION - a iS Brook ano Compron Bay - 5 - Brook To ATHERFIELD - Sanpown Bay - - - 2 * S CHAPTER III. LOWER GREENSAND OR UEPER NEQCOMIAN « — INTRODUCTION - Compton Bay - z 3 ATHERFIELD :— The Atherfield Clay and Perna Bed - - . The Ferruginous Sands - a < The Sand-rock Series - n - < = Sanpown TO BoONcCHURCH :— The Atherfield Clay and Henmpinoss Bands - The Sand-rock Series = Sanpown To CULVER CLIFF - PunFIELD Cove - - - CHAPTER IV. LOWER GREENSAND—continued. INLAND SECTIONS :— (1.) Antone THE CenTraL Downs - - - . (2.) AROUND THE SOUTHERN Downs - : INDICATIONS OF CoNDITIONS UNDER WHICH THESE BEDS WERE DEPOSITED - - = z CoRRELATION WITH THE MAINLAND - CHAPTER V. LOWER GREENSAND — continued. THE CARSTONE :— INTRODUCTION - Compton Bay To Rep Curee - From Niron AND BLACKGANG TO SHANKLIN AND BoNcHURCH Pace iii vil ll 16 18 21 oF 26 30 32 34 34 37 40 44 47 49 52 50 57 x CHAPTER VI. THE GAULT AND UPPER GREENSAND. Pace THE GauLt :— INTRODUCTION - - - - - - 60 LANDSLIPS S J ss 5 = - 60 DEscRIPTION OF SECTIONS - - - - -~ 62 CoRRELATION WITH THE MAINLAND - - 65 Upper GREENSAND :— INTRODUCTION - - - 65 Coast Sections :— 1. Compton Bay - - - 68 2. Blackgang i. Shanklin - - - 68 3. Culver Cliff - - « - 70 INLAND SEcTIONS :— 1. Along the Central Downs - - - 70 2. Around the Southern Downs - - - 72 CHAPTER VII. THE CHALK :— INTRODUCTION” - - - - - 73 CHLoRITIC MaRL - - _ 2 79 Upper, MippLe, anD LowER Cade — I; ‘Compton Bay along the Central Downs to Culver Cliff - 82 2. The Southern Downs - - 3 90 Division or THE Upper CHALK INTO Bowes - - 9 CHAPTER VIII. EOCENE :— INTRODUCTION : - - a - 94 Reapine Beps - - - - - 94 Lonpon Cray - - - - ‘ - 97 Lower Bacsuot Beps - & - 101 On THE FLora or Atum Bay, By J. STARKIE GARDNER - 104 CHAPTER IX. EOCENE—continued :— BrackLEsHAM AND Barton Beps:— BrackLesHAM Beps - * 3 < - 109 Barton Cuiay “ « 3 2 117 Heapon Hitt Sanps - 3 S -~ 129 CHAPTER X. OLIGOCENE :— InTRODUCTION : - - S - 124 Heapon Beps~ - é 5 . s 1P8 CHAPTER XI. OLIGOCENE—continued :— OsBoRNE Beps~ - - - a < ks - 148 BemsBripGe LIMESTONE - % - s - 158 BEMBRIDGE MaRLs - - 2 . - 170 XI CHAPTER XII. OLIGOCENE—continwed :— Hamsteap Brps = 2 - “ CHAPTER XIII. PLEISTOCENE AND RECENT DEPOSITS :— CLASSIFICATION = = = is s < I. ANGuLar Fiint Gravet or THE CHALK Downs II. Puareau Gravets :— Their Age - - - St. George’s Down to East Cowes and Odbome Parkhurst Forest to West Cowes - - Thorness and Rew Street - Hamstead - - Calbourne - - Headon Hill - Wootton Bridge to Ryde - - - Ryde and St. Helen’s— - Bembridge - Blake Down, Newchurch, Areas, aed Sandown Brook . a II]. Tue Vattey Graves anp Brick-EartH :— Mode of Occurrence The Eastern Yar - Wootton Creek The Medina Valley The Western Yar - IV. Beps Now FORMING, OR OF RECENT DaTE :— Alluvium and Peat of :— a. The Western Yar and the Coast from Freshwater to Yarmouth = - . b. The Coast from Freshwater to Blackgang - c. The Medina - - d, The Eastern Yar - Blown Sand & - a ‘ Chalk Talus - : * ie CHAPTER XIV. DISTURBANCES AND FAULTS . - 5 CHAPTER XV. PHYSICAL GEOGRAPHY - - - 7 3 CHAPTER XVI. ECONOMIC GEOLOGY - . 2 Pace 184 208 209 210 212 214 215 215 215 216 216 216 Y1y Dhy 220 220 221 929 QOD 223 208 230 235 235 237 237 239 248 251 xli APPENDIX I. PacE RAINFALL - - a : A 2 256 APPENDIX II. TABLES OF FOSSILS :— I. Wealden - s . - - 258 II. Lower Greensand - - 261 III. Upper Cretaceous - - 268 IV. Eocene and Oligocene - - 282 V. Fossil Ostracoda of the Isle of Wight, by Prof, Ts R. io E.R.S. x : 298 APPENDIX III. WELL SECTIONS AND WATER SUPPLY Ss - 800 APPENDIX JV. BIBLIOGRAPHY : - 319 INDEX - - - - - - 338 Fig. ¢ ae eee ob wl . Chara Wrightii - - . Diagram of Colwell Bay Cliffs « - . Chara Lyellii = - - - je . Section ep Binstead - - - a 3 xili LIST OF ILLUSTRATIONS. . Cypridea pitas - s < Cyrena - “ . . Paludina Havieoun Unio valdensis - Sketch of Wealden Beds between Brixton Chine and Barnes Chine - “ : Oypris cornigera and Candona Mantelli - - The Sand-rock Series in Compton Bay - . Perna Mulleti - 4 2 . Exogyra sinuata - . . Panopea plicata - - 2 z . Gervillia anceps - - ‘ . Terebratula sella . Junction of the Gault and Lower Greensand in Compton Bay - . Junction of the Upper Greensand and Gault in Compton Bay - . Freshwater Bay from the West. From a sketch by Prof. E. Forbes . Junction of the Chalk and Lower Tertiary Beds in Alum Bay eet Cutting just south of Brading Station - 8, Pholadomya margaritacea - . 9, Panopsa intermedia - : . Ditrupa plana - - 5 . Pinna affinis - - - = . Cardita planicosta - a . Turritella imbricataria & . Phorus agglutinans - . Murex asper- - Fusus pyrus - - x . Psammobia compressa - - A . Rostellaria rimosa - . Crassatella sulcata - - . Voluta luctatrix - . Fusus longeevus . Conus dormitor - . Calyptraea trochiformis - - ‘ . Typhis pungens - = . Pecten reconditus - . . Section of the north-eastern corner of Headon Hill ~ . Cytherea incrassata - - . Ostrea flabellula - - fe . Potamomya plana a 4 . Unio Solandri - . Cerithium concavum — - . Melanopsis subfusiformis - . Cerithium pseudocinctum . Planorbis evomphalus . Limneea longiscata - . Paludina lenta - - ee Oe a oe We a PLATE PLATE PLATE PLATE PLATE . Bulimus ellipticus . Helix globosa_ - . Planorbis discus . Achatina costellata - - . Section of the lower part of the Cig near Porchfield - . Chara tuberculata - - - = . Cyrena pulchra - - . Cerithium mutabile - . Cyrena semistriata . Arca Websteri - - . Hydrobia Chasteli - - - - 2. Pseudocythere Bristovii : . Potamocypris Brodiei - . Melania turritissima = - . Cyrena obtusa - - - . Melanopsis carinata - . Ostrea vectensis - . Cerithium plicatum - - - - . Corbula pisum - - . Cerithium elegans - - . Corbula vectensis - . Cyclas Bristevii - 3. Unio Gibbsii - - . Melania fasciata - . Panopeea minor . Sketch of Hamstead Clift . Ostrea callifera - . Cytheridea montosa —- - - - . Section in Valley Gravels at the eastern end of Compton Bay _- . Freshwater Bay from the East. From a sketch by Prof. E. x1V yopoeos . 1 se tb bos 8 oe ee ¥orbes - . Ss 2s . Tufaceous Deposit of Totland Bay . Sketch of Gravels with hazel nuts in Shippand’s 8 Chine. - . Section between How Ledge and Colrvell Chine - - . Diagram Section to show variation in the dip of the Strata as the Surface is lowered - = = At the end of the Book. Pace 159 159 161 162 164 169 172 172 173 173 175 175 178 181 181 182 182 185 185 185 I. Index Geological Map of the Isle of Wight, with a longitudinal section across the Island from Rocken ¥nd to Norris. II. Section along the Coast from Afton Down, near Freshwater, to St. Catherine’s Down. III. Comparative Sections of the Cretaceous Rocks of the Isle of Wight and of the Dorsetshire Coast. IV. Longitudinal Sections. No.1, From Totland Bay over Headon Hill to High Down. No 2. From near Cliff End, over Sconce, to the sea under High Down Beacon. V, Comparative Vertical Sections of the Oligocene or Fluvio-Marine Series. THE GEOLOGY OF THE ISLE OF WIGHT. THE GEOLOGY OF THE ISLE OF WIGHT. CHAPTER I. INTRODUCTION AND TABLE OF STRATA. THe Isle of Wight is of a lozenge shape, with its longer axis extending nearly east and west from the Foreland to the Needles, a distance of 224 miles, and its shorter axis nearly north and south from West Cowes to Rocken End, a distance of 13 miles. The northern apex is situated immediately opposite the mouth of Southampton Water. The two northern sides of the Island are nearly parallel with the mainland of Hanipshire, from which they are separated by the Solent on the west, and on the cast by the sea between Southampton Water and Spithead. The nearest point to the mainland is Cliff End, which is only a mile distant from the bank of shingle and sand on which Hurst Castle is situated; but the Solent is generally from two to three miles in width, while the channel east of Southampton Water reaches a breadth of four miles. The area of the Island, as deduced from the Ordnance Survey, is 155 square miles 370.209 acres, in which are included 122.684 acres of water, 9 square miles 34.076 acres of foreshore, and 434.454 acres of tidal water. It is divided into East and West Medina by the River Medina, which, rising near the southern apex of the Island, runs northwards through a gap in the chalk range, and discharges itself into the sea between East and West Cowes.* A more marked physical division is that produced by a bold range of Chalk Downs, which extends from the Needles to Culver Cliffit The area lying to the north of this range is occupied by Tertiary strata, and is chiefly characterised by the heavy and clayey nature of the land, and by the numerous woods which cover its surface, especially east of the River Medina. The tract of land south of the chalk range is occupied chiefly by the Lower Greensand, and presents a * Tho Isle of Wight was called “ Meden” in former times. The Roman name for it was Vectis. In Camden’s Saxon Chronicle and Domesday Book and in the oldest records it is written “ Wict.”—II. W. B. + Culver Cliff (after the Anglo-Saxon name “culfre,” a dove) was probably so named from its being the resort of numerous wild pigeons of asmall species (Columba saxitilis) which made it their haunt. DPcunant states that “ these birds make ata certain season most enormous flights ; they come daily in vast flocks, as far as the neighbourhood of Oxford, to feed on the turnip-fields, and return again to these and Freshwater Cliffs, where they pass the night.” (Pennant’s Journey, p. 151.) Culver Ciiff was also famous for a breed of hawks in the time of Queen Elizabeth.— H.W. B. » E 56786. A cy ip 2 GEOLOGY OF THE ISLE OF WIGHT. striking contrast to the north side of the Island im its generally light and loamy soil, and in the absence of woods. In the southern part of the Island also is found a group of hills, capped by outliers of chalk, which rise to a far greater height than any prt of the generally low Tertiary district, and in fact form the most elevated tract in the Islind. A considerable part of both the northern and southern parts of the Island is overspread by gravels and Alluvium, the former being of considerable thickness and commercial importance. The following table gives in descending order the formations shown upon the map :— Blown Sand - : Alluvium - - - ' Recent. Peat - River Terraces (Gravel) Angular flint-gravel of the Chalk Downs Pleistocene. Plateau Gravel - - - Hamstead Beds - - Bembridge Marls | otposine —_—_———- Limestone - }[‘ Fluvio-marine ” Osborne Beds - | of E. Forbes.*] Headon Beds Headon Hill Sands - = Barton Clay Bracklesham Beds 2 - Lower Bagshot Beds e London Clay | Reading Beds - = J Chalk-with-tlints 2 | | J a SSIS Eocene. Chalk Rock Middle and Lower Chalk with }- Melbourn Fock. | Chloritic Marl - | Chert Beds d Sands = Gault - Carstone B sie ae - | Lower Greensand or | ‘erruginous Sands { Upper Neocomian. + Lower Crets ee Clay pp > er Cretaceous. Wealden Beds with beds of sandstone - Upper Cretaceous. : Upper Greensan The above formations will be described in ascending order commencing with the Wealden—the lowest and oldest strata seen in the Isle of Wight. * The term ‘ Vectian’’ was proposed for this group by Prof ilh has not been generally adopted. eee errr CHAPTER LIL. THE WEALDEN BEDS. INTRODUCTION. Trest beds rise to the surface on the southern and eastern sides of the Island, where they have been elevated along the anticlinal axes of Brixton and Sandown. The entire area occupied by them is very inconsiderable, not exceeding five square miles ; and there is no good section inland. On the coast, however, for six miles from Compton Bay te Atherfield, they are well exhibited in the cliffs (see Plates I. and II.), and there is also a tolerably fair exposure of them on the coast in Sandown Bay. The lowest beds exposed in the Island are the variegated Wealden clays and sandstones of Brook Bay. Judging from the section at Swanage, where the whole of the Wealden formation is displayed, there may be about as great a thickness of these beds below the sea-level in the Isle of Wight, as is seen cropping out in the cliffs. The Wealden Beds include two difterent but perfectly conform- able types, the one consisting of dark-blue or almost black shales, evenly bedded and splitting into thin laminz, together with layers of shelly limestone and ironstone, and very thinly laminated * paper-shales,” crowded with the sheils of minute ostracoda (Cyprids). Fossils are abundant in this type, though the number of genera is somewhat limited. Paludina, Cyrena (Cyclas), and Unio occur in profusion everywhere, and licarya (= Cerithium, Mcelania, Potamides of previous writers) is abundant at Atherfield. This type is found invariably at the top of the Wealden formation, immediately under the Lower Greensand, but appears also to be interstratified with the type now to be described. Fig. 1. Fig, 2. Fig. 3. Cypridea spinigera, Sow. Cyrena. Paludina fluviorum, Sow. The other type, under which the Wealden beds appear, is that of red, green, and variegated marls and clays (curiously resembling the Keuper Marl), with numerous included bands of sandstone of variable thickness. The bedding is far from regular, and fossils are comparatively scarce. A large freshwater shell ( Unio valdensis, Mant.), dirfled wood in great abundance, the remains of fish, and the water-worn bones of terrestrial reptiles are met with throughout the group. 4 GEOLOGY OF THE ISLE OF WIGHT. The correlation of these two groups of the isle of Wight with the Wealden strata of the mainland has caused some diversity of opinion. Dr. Fitton and the older authors spoke of the gus group only as Wealden and of the lower as Hastings Sand. By the Geological Survey they were both included under the name Wealden, but in 1856 Mr. Godwin Austin® stated that the Weald Clay might be scen “to alternate with, and therefore to be synchronous with, the marine Neocomian.” Professor Judd t also in 1871 stated that he looked upon “the great mass of variegated strata containing only freshwater and terrestrial fossils Sth) a as the Wealden proper,” and that the upper group or Punfield Beds, as he called them, “may be regarded indif- ferently either as the highest member of the Wealden in our classification of terrestrial strata, or as a portion of the Neoco- mian in our grouping of the marine series.” This view of their relations was suggested by the intermingling of brackish water or marine forms such as Curdita, dwarfed oysters, and the estuarme Vicarya with purely freshwater forms such as Paludina and Unio. But unfortunately, the true base of the Lower Greensand not having been then discovered at Punfield, a large part of this forma- tion, with its highly characteristic fauna, was included in the “Punfield Beds” of Professor Judd, with the result that the fauna of these Punfield Beds was made up partly from the Lower Greensand and partly from the Wealden. This fact was first ascertained by Mr. Meyer} in the years 1871-72. He observed that the Atherfield Clay with some of its characteristic fossils occurred beneath the fossiliferous zone from which many of the marine Punfield fossils had been obtained, and that the characteristic cypridiferous shales with lmestone occurred beneath and nowhere above this marine band. His con- clusions were strengthened by observations made by the Geolozists’ Association§ in 1882, and have been fully confirmed by the exami- nation that was undertaken for the purpose of the present Memoir. The results and measurements obtained during this examination will be incorporated in the following pages, but it may be stated here that at Punfield, as in the Isle of Wight, the paleonto- logical break between the Wealden and Lower Greensand is complete, and is accompanied by evidence of considerable erosion of the former. The name of Punfield Beds, therefore, having been applied to strata belonging to two distinct groups, will not be used here. But at the same time it will be convenient to distineuish the beds for which the name was intended from the variegated Wealden type which has been mentioned above. The name Upper Wealden is scarcely suitable, for, though generally found at the top of the Wealden formation, they appear also to be interstra- * Quart. Journ. Geol. Soe., vol. xii. p. 66. { Lbid., vol. xxvii. p. 207. t Lbid., vol, xxviii, p, 248, and vol. xxix. p. 70. § Proc. Geol, Assoc,, vol. vii. p. 388, WEALDEN BEDS. 5 tified at various horizons in it.* On the other hand the most striking characteristic of the beds is their shaly character, as com- pared with the almost structureless variegated clays, and the name of Wealden Shales will perhaps be sufficiently distinctive. The Wealden Beds rise from beneath the Lower Greensand in Brixton and Sandown Bays, on the south-western and south- castern sides of the Island respectively. In both bays they rise with a steep dip from beneath the rocks which compose the central range of the Island, On receding from this central axis of disturbance the angle of dip grows less, until the beds finally assume a horizontal position, as may be seen near Brook, in Brixton Bay, and in Sandown Bay at the point where the coast-line cuts the Alluvium of Sandown Marsh. Still further south in each of these bays a gentle southerly dip sets in, and the higher beds of the Wealden series pass in succession below the beach. The structure, therefore, is similar at each locality, namely, that of a dome with a steep side to the north. Brook anp Compton Bay. (See Plates IF. and IIT.) The lowest beds displayed in the Island are those forming the shore near Brook and at Sedmore Point, half a mile south-cast of Brook Chine.t At Sedmore Point a bed of sandstone forms the foot of the cliff for about 400 yards. Above it are blue, purple, and deep-red marly, overlain about half-way up the cliff by an impersistent bed of sandstone, with a gravelly band about 18 inches thick, made up of fragments of sandstone with many small bones, at its base. Cyclas, Paludinu, and Univ are recorded by Fitton from this bed. The upper part of the cliff consists of purple and blue marls, with light-coloured bands containing much lignite. Between this Point and Brook Chine the strata have slipped, forming an undercliff, known as Roughland, along the whole length of which (some 500 yards) there is no clear exposure of rock in place, though the extent of the slip shows that the beds must be chiefly clays. As we approach Brook Chine the section becomes clear again. A greenish band may be seen to rise westwards from beneath the beach, and to run along the upper part of the cliff past Brook Chine to a small chine 180 yards south of Brook Chine, where it descends once more to the beach. This bed is easily traced by its colour, and by the fact that it is crowded with large flattened masses of lignite, especially to the south and west of Brook Chine. It shows that the strata form a * Geology of the Weald (Geological Survey Memoir), and Drew, Quart. Journ. Geol. Soc., vol. xvii. p. 283. : heh Meat + The local name for the deep fissures or gullies, which are termed chines in the Isle of Wight, is derived from the Anglo-Saxon cin, a cleft. Wyclif speaks of the “ chyne of a ston-wall.” So also, Spenscr— « Where byting deepe, so deadly it imprest, That quite it chyned his backe behind the sell.” - —Faerie Queene, b. iv., canto 6, xill. 6 GEOLOGY OF THE ISLE OF WIGIIT. gentle anticline, the centre being near Brook Chine, the deep- red and variegated marls of which are perhaps the lowest rocks seen in the Island. The lignite bed described above appears to pass out to sea south of, and therefore below, a similar bed which is ecen at Brook Point, but the strata are so variable that it is impossible to speak with certainty. The section at the Point shows upwards of 100 feet of red, purple, and blue clay with impersistent bands of sandstone, underlain by 13 feet of grey clay, the lower part of which contains numerous flattened masses of black shining lignite. This lignite band rests upon a bed of hard sandstone, to which the Point owes its existence. It is a whitish or pale-grey rock, about 6 feet thick, containing fragments of marl and clay, and with iron-pyrites abundantly disseminated through its upper part. It is irregu'arly stratified, and its surface is undulating and covered with fucoidal and hollow vertical markings. Below and partly imbedded in this rock lie the scattered trunks of coniferous trees, known as the “ Pine Raft.” They were first observed by Webster in 1811,* but were more fully described by Mantell in 1846. The trunk: lie prostrate in all directions, broken up into cylindrical fragments. They are covered by thin bark, now in the state of lignite, the wood having been con- verted into a black or greyish calcareous stone,t with much iron pyrites. Many of the trees still present traces of weody structure, and the annular rings of growth are clearly perceptible; but they are traversed also by numerous threads of pyrites. The trunks are generally of considerable magnitude, bey from one to three feet in diameter; two upwards of twenty feet in lencth, and of such size as to indicate a height of forty or fifty feet when entire, were noticed by Mantell. The “Pine Raft” can be seen at low water only. During spring tides it may be observed to rest on variegated inarls, but all attempts to trace it eastwards from Brook Point have failed, pro- bably on account of its being of local development only. The purple marls forming the cliff above it are apparently the same beds that have made the great slip of Roughland, and the Pine Raft, if 1t is continuous, should be found in the cliff near Sedmore Point ; but though many large fragments of trunks are lying on the beach, there is no bed in the cliff exactly corresponding to that of Brook Point. A: suggested by Mantell, the trees were probably drifted from a distance, in the same manner as the trunks, brought down by the Mississippi at the present day, are deposited in large rafts in the delta of that river. It is not to be expected, therefore, that * Englefield’s Isle of Wight. 1816. ft Quart. Journ. Geol. Soc., vol. ii. p. 91. 1846, t Unlike the trunks in the dirt-beds of the Isle of Portland, which ili cified. Professor Way pointed ont the probability “ that the fossil forest inkeniea in - ae ee at Brook Point is impregnated with phosphoric acid, instead of carbonic acid, as is generally as eg , ; rR aes g y assumed Tourn, Roy. Ayric. Soc. of England, WEALDEN BEDS. 7 the “ Pine Raft” is of wide range, or that the horizon at which it occurs should be recognisable when the trees are not present. There is no evidence that any of the trees in this or any other part of the Wealden series grew upon the spots where they are new found. In the cliffs of this neighbourhood there have been found also the cones to which more special reference is made in the fossil list on p. 258. Mantell records also the occurrence of Clathraria Lyellii as a pebble on the beach of Brook Bay. , The large freshwater shell, Unio valdensis, was first observed by Mantell “in the sandy clay beds immediately above the fossil forest” (op. cit., p. 94). It occurs also in some hard irony con- cretions, which have fallen to the beach on the west side of Sedmore Point. Fic. 4. A large number of reptilian bones Unio valdensis, Mant, 280 has been obtained from the cliffs. i Those on which the species Igwanodon Seelyz was founded were obtained by Mr. Hulke in the small chine 180 yards south of Brook Chine.* — Ornithopsis Hulhei also occurred in Brook Bay, and footprints, believed to be those of an Iguanodon, have been found 600 yards to the west of Brook Point, and near Sedmore Point by Mr. Beckles.t The prints occurred as casts, attached to a thin bed of hard sandrock on the shore at low water. For further information on the fossils the reader is referred to the list on p. 258. As we proceed from Brook either westwards to Compton or eastwards to Atherfield, an ascending section in the same beds is provided in the cliff, the distance to be traversed in the former case before reaching the top of the Wealden beds being less on account of the greater steepness of the dip. We will first examine the cliffs westwards, as far as the great slip which marks the position of the Atherfield Clay (Plate II.). On rounding the Point we find the cliff composed principally of red and purple marls for a distance of about 700 yards, the thickness of strata amounting to 439 feet. In the marls there occur beds of sandstone often conspicuous from their whiteness, and a few green bands containing lignite. Passing over some thin and impersistent sandstones near the Point, we meet the first noteworthy bed 170 yards further west, where there is seen in the upper part of the cliff a grey clay packed with lignite, resting on a white sandstone 5 feet thick, but thinning away westwards. This is overlain by purple and variegated clays, and 100 yards westwards a second bed of white sand-rock, 7 feet thick, succeeds. A third bed, 16 feet thick, is seen on the east side, and a fourth, Eee * Quart. Journ. Geol. Soc., vol. xxxvili. p. 185. 1882, ¢ Ibid., vol. xvii. p. 443. 1862. 8 GEOLOGY OF THE ISLE OF WIGHT. 9 feet thick, on the west side of Shippard’s* or Compton Grange Chine, the last-mentioned rock being of a pinkish hue from the abundance of grains of pink quartz in it. At190 yards distance from this chine we see the purple strata pass up into characteristic blue Wealden Shales with abundant Cyrena, Paludina, Cyprids, fish-remains, and fragments of ferns. These blue shales, which, like the Cowleaze beds, are interstratified with sands in the lower part, are about 222 feet thick, and are fully exposed up to and in a small chine 350 yards west of Compton Grange Chine, but beyond this they have been disturbed by slipping. They secm, however, to be succeeded by red marls at a point in the top of the cliff 50 yards west of the small chine, whether by a fault or natural superposition will be discusscd subsequently. Continuing along the top of the cliff, where the strata are in place, we see a thickness of 193 feet of purple marls with irregular white sand-beds and with three beds of grey or white clay and sand with lignite, the highest and lowest containing large tree trunks in addition to a great abundance of small fragments of wood. These variegated strata pass up into blue shales and sandstones with bands of ironstone, which in the exposed parts have weathered into a cinder-like rock. About 27 feet of these blue deposits are seen in place, and they are followed ly blue paper- shales with Cypris and slabs of Cyrcna limestone with fish-bones, scen only in slips, but estimated to have a thickness of 65 fect. These are overlain by the Lower Greensand. The question now arises whether the blue shales last described are the same beds as those near Compton Grange, the strata being repeated by a strike fault with a downthrow to the south; or whether there are two horizons at which this type of the Wealden eeries makes its appearance in the Isle of Wight, as on the mainland. It is in favour of the theory of a fault, that ncither at Atherficld 5 miles distant, nor at Sandown 15 miles distant, nor at Punfield 20 miles to the west, can more than one group of shales of this type be seen, and that only at the top of the Wealden series. The thickness also of the beds visible between Brook Point and the top of the lower blue shales is much the same as that between Brook Point and the top of the Wealden Shales of Shepherd’s Chine, namely, at the former locality 676 feet, of which 454 are variegated, and in the latter 754 feet, of which 562 are varicgated. ‘The blue shales, moreover, strongly resemble the beds of Cowleaze and Shepherd’s Chines. But on the other hand, the differences in the two sections of Compton Bay are so great, though only a quarter of a mile apart, that cven allowing for the variability of Wealden strata, it is difficult to suppose that the same set of strata appears in each. The variegated beds of the upper part are characterised by au abundance of lignite associated with white elays; in those below lignite is scarce, but several bands of sand-rock stand out “ Not to be confounded with Shepherd’s Chine, near Atherfield, WEALDEN BEDs. 9 conspicuously. In the uppermost blue beds the sandstones, except close to the hase, are not prominent; in the lower they form a marked feature. The thickness, moreover. of the lower set reaches 222 fect, that of the upper only about 92 feet, while, lastly, fossils occur abundantly close to the base of the lower set of blue shales, but have not been found in the 27 feet of the upper set which are clearly exposed. The evidence is therefore rather more in favour of there being two horizons in the Wealden series of Compton Bay, at which fossiliferous shales occur. Which of the two sets of shales should be compared with the Wealden Shales of Shepherd’s Chine remains doubtful. If we correlate the lower set with the shales of Shepherd’s Chine, we have nothing to represent the upper 285 feet of Wealden Beds of Compton Bay. But no evidence can be found of so great an erosion of the Wealden Beds as the absence of the strata in question would seem to imply. We may more probably view the lower shales of Compton Bay as a local intercalation of this Wealden type among the variegated beds. Before leaving Compton Bay we will refer briefly to the section of the Wealden Beds at Punfield, on the coast of Dorsetshire, already referred to. The Wealden Shales at that locality form a well-marked subdivision at the top of the Wealden group. They have a total thickness of 344 feet, cypriditerous paper-shales, hard limestone with Cyrena and Paludina, and some thin bands of sandstone being interstratificd with them. Down- wards they pass into white sandstone, grey clays with white sands or brown sandstone, and so into red marls. About 200 feet below them lie white clays and sands, with much lignite and con- cretionary lumps containing Unio valdensis, The total thickness of the variegated beds of the Wealden, near Punfield, has been estimated by various observers at 1,500 to 2,000 feet. Desecnding Section of the Wealden Beds from Compton Bay to Brook Point, (Sce Plates IL. and III.) Fr. Ivy, Perna Bed (Compton Bay). ( Beds seen only in land-slips, consisting of Cyprid shales with | a hard band, containing numerous fish-remains in the “ upper part, bands of limestone and ironstone; estimated at 65 0 2 | Blue and prey clay an sand - - - 2 a De Rn | Sand - - a w DO a< Blue shale - - - ~ a = 8 0 rs | White sand and site = - - - 3 0 @ | Ochry band (cinder-bed) passing into a soll ironstone wets e less weathered - - - - - - 0 6 Blue shale = “ “ - - - - 17 0 Cinder-bed, as above - - - « 0 6 Grey clay, with large trunks of trees - : = 9290 Purple marls - - - tl 0 White sandstone and ng tlk lignite ” - 9 0 Purple marls with sand- Tred bout 55 0 Fine white sand - - - - 3 Pale purple clay - . a # s 12 10 Wealden Shales. ahs, GEOLOGY OF THE ISLE OF WIGHT. Fr White clay, crammed with great masses of lignite and trunks of trees - - : 5 Yellow and white clay, passing down 6 Purple marls, about - 39 White sandy clay, with bones - - : 7 Deep red marls, about le Here there is possibly a large fault, repeating the Wealden Shales of Compton Bay (see p. &). ( Blue shales, not well seen, about - 20) Shales, seen in the west bank of a small chine - - 2i Paper shale, with Cyprids - - - 90 Cyrena limestone - . 0 Shales with lines of sand, Cyprids fiers and fee - 1 Paper shales with Cyprids = - 2 Cyrena limestone - 0 Paper shales with Cyprids (in the east bank of the anal chine mentioned above) - - - - 14 Shales, not well seen - - - 29 Shale, with lines of sand and grit containing ferns (rises from below the beach on the east side of the small chine) - 51 | Yellow and white sand-rock, with large emus of pinkish quartz - - - - 5 Blue shale - - - - 3 Sand-rock, as above - - - ly Blue shale, with thin ironstone in the lower part : 5 Coarse grit, with grains of pink quartz Shale parting - - - : - - «= 2 Sandstone - - Blue shale - - 0 Tronstone, with Unio, Eprom Paludina, Cyprids and “Beef” 0 Blue shale - - - 6 Fine ochry and dusky sand - - 1 Fine white sand-rock - - - 2 Shales, with Pa/udinu and Cyprids - 5 Lenticular ironstone - - 0 Sandy shales, with ferns - - - - 5 Shale 2 6 Shales, full of Cues ‘and Producing 2 3 Sandstone, with lignite 2 0 White sandy clay —- = ul Blue marly clay, with large concretions and absooke fossils - 8 White and blue marly clay = 2 Pale variegated marl - 5 {White sandstone, with irregular top - 3 Purple marls, estimated at : 7S White sandstone, containing an abundance of grains of pink quartz (crops out west of Compton Grange Chine) - 9 Red, purple, and green marls of Compton ‘Grange Chine 7s White sandstone (east of Compton Grange iig) 16 Variegated marl - 30 Red sandstone - - - = 2 to 4 Greyish blue marl —- : “ 10 White sandstone - - - = 7 Purple marls - - - - - 64 White band - - . 1 Purple marls - - : 40 Grey clay packed with lignite - - ‘ Sf White sandstone, thickening eastwards - 5 0 to 5 Purple marls 2 4 a6 Red sandstone and marl, thinning ont east at Brook Point 6 Purple marls - ' - - 5 41 Red marls - - x . le Grey sandstone - 0 to 2 . In, oo Sso FeAOCW OOS { bo | Shales, with a band containing Unio, Poludina; atid Cyprids = near the middle, and sandy beds, peetanne rene! in the lower part - - - - 40 0 Sandstone of Cowleaze Chine and Barnes High, manatee, with bands of Cyrena - 8 0 Sandstone of Gonlehe Chine and Bamies High, thin-bedded, with shale - 13. 0 Blue shales,* with Bake and Pulidive’ in the is ia Cyrena and Paludina near the bottom - 19 0 White sand and clay* - - - - - 2 6 White rock - - = - 2 6 | Red sand, with bones (ppaianhedue Bed) - 3°40 Red and mottled marls, rocky and ripple-marked at ihe fope < - 44 0 White and yellow sand, with fragments and large trunks of lignite, passing westwards into sandstone, and splitting up and dying away before reaching the top of the chi - 9 0 Pale blue clay, becoming purple downwards 29 0 Hard green bed, containing lignite and bones Sen in the ice of Barnes Chine) = ~ 2 0 Deep-red marls - - - - 7 = -§ 0 Purple and mottled marls- - 35 0 Sandstone, with clayey beds (crosses Barnes Chine) + - 13 °0 Deep-red marls, purple below si - YR 6 Conglomeratic grit, with an occasional pebble of quartzite, or of sandstone - - - 2 = BO Pale mottled clay — - - 2 = 14.6 Green and white clays, with iignte - S x BO Purple mottled marls - Si - 9 0 Deep-red marls - - - - - 13 0 White sandy bed - - a . é = 3.0 Pale purple and mottled marls 21 6 Fine white sandstone (crosses the bottom of Ship Chine) 4 0 Mottled marls - 25. 6 Black bed of Brixton Chine; gna bones, “Bate vatdensis = 2 6 White sandy marl - 3.0 Mottled red marls of Brixton Chine, with a ‘igaite bed near the middle - - - 94 0 Green sandy bed, with bones - 2.0 Red and white sandstone in beds of i to 3 feet, with partings of marl, and pockets containing shale and sandstone frag- ments; a band of gravel of sandstone fragments, 3 inches thick, at the base, nae fragments uf bones - - 17 0 Mottled marls 49 0 Pebbly band, lignite atl eis oe "panei (top of east bank of Chilton Chine) - 2 -50) Red and mottled marls 23 0 Current-bedded sandstone (near the bottom ot Chilton Chine) about - - - - 12 0 * These beds give a slightly differents ection in passing from Cowleaze Chine Barnes High. See p. 13. 16 GEOLOGY OF THE ISLE OF WIGHT. Fr. In. Mottled marls - “ 7 = : = 28 0 Purple marls, with white concretions - 2 win om Red marls passing down into white sandstone, with partings of marl, current-bedded in large sweeping curves - - 9 O Massive sandstone, bands of bone and sandstone breccia running irregularly through; 6 to 18 inches of gravel at base, with bones. This bed thins away westwards, and is last seen at Sedmore Point - - - 18 0 Deep-red and purple marls (at Sedmore Point) - 20 0 Current-bedded sandstone of Sedmore Point - - - 8 OF Sanpown Bay. The Wealden formation occupies a mile and a half of coast in this bay, and extends inland for a little over a mile. The axis of the anticline, which has already been described, les nearly «breast of the stone fort, and trends a little north of west, in a direction parallel to the range of Brading and Bembridge Downs. The southern side of the anticline is entirely concealed by buildings on the cliff, and by sand on the fore-shore. The first exposure on the northern side is met with at the east end of the groins, where mottled clays with bands of sandstone form gentle undulations, with a general tendency to dip to the north-east. A short distance further on the dip increases to 11°, and finally to about 20° to the north-east, before the Wealden beds are lost to sight below the Lower Greensand of Redcliff. The Wealden series is divisible here as in Brixton Bay into a lower group of variegated clays, and an upper group of fossili- ferous shales. The lower group forms the low cliff or bank which extends as far as Yaverland Fort. It consists of mottled red, purple, and white marls, but is much obscured by slipping. The fort stands on a low escarpment formed by a bed of sandstone about 8 feet thick; possibly the same bed that forms the corresponding feature of Barnes High in Brixton Bay, for the base of the blue fossiliferous shales is found at about the same distance below it in the two localities, This sandstone is seen again in the road-side south of Yaverland, and in a sand-pit 300 yards south-west of Sandown Farm. There it exceeds 18 feet in thickness, and dips to the south-west at 9°, The details of the beds above and below the sandstone in the cliff are as follows :— Fine black shale, Cyprids very abundant. = Blue sandy shale, with lines of brown grit % - 10 Sandstone, about - - 8 Blue shale, base not seen - - a3 Ww Blue fossiliferous shales, not well seen, about 30 Purple and mottled marls. , 58 The beds above these are much obscured b ; slips, but can } seen to consist of shales of the usual type of Qe eS the upper group, WEALDEN BEDS. 17 without any of the purple variegated marls, The junction with the Lower Greensand ean be “exposed by digging, as will be deseribed, but the top beds of the Wealden are not cle: uly seen, The details in the following scetion are therefore quoted from Professor Judd’s paper on the Punfield Formation.* Fr. In. Lower Greensand. Blue paper-shales - S 3.09 os light-coloured Aad pyc - - 1 oOo e Dark-coloured paper-shules (with Cypridea mabbanshs)p and x several layers of nodular ironstone - 4 0? = |“ Beef” - Oo 7 iS 2 Limestone, crowded with Cyrena and a few oysters - 0 6 § \ “Beef” - . - - - 0 23 3 Finely laminated pynitie lay - 0 9 © | Ferruginous band, almost entirely made up of shells Ce (oysters and small univalves) - - - 0 3 Other beds of dark blue laminated shales, with geeactotel beds of limestone, imperfectly exposed; seento 30 or 40 0 The total thickness of the Wealden Shales, as estimated from the breadth of outcrop and the dip, is about 170 feet. The same assemblage of fossils occurs here as in Brixton Bay. Fragments of the thin bands of limestone containing Paludina and “Cyrena may be found in abundance upon the beach, together with pieces of lignite, while the Cyprids occur in profusion in certain bands of finely Jaminated paper-shales. A pelvis and the external metacarpal bone of the right foot of Iguanodon have been discovered in the sandstone below Yaverland Fort. + Vertebre, a femur, and ribs of the same animal are stated by Mantell to have been found near the same spot.t A femur was found also in the low cliff of Weald Clay to the west of Sandown Fort, a part that is now obscured. The beds are stated to have dipped slightly to the west.§ It will be observed that, if the sandstone under Yaverland Fort is the same bed that forms Barnes High, the horizon of the Hypsilophodon band is clearly fixed in Sandown Bay; but no remains of this reptile have yet been discovered. Mantell notes that some “ grey sandstone, interspersed with clay,” near Yaver- land Fort, “several cones of a plant allied to the Zamie, mixed with fragments of lignite, have been discovered.” || For further particulars concerning the fossils the reader is referred to the fossil lists on p. 258. * Quart. Journ. Geol. Soc., vol. xxvii. p. 220. 1871. } Rev. Dr. Buckland. Proc. Geol. Soc., vol. i. p. 159. 1826-33. t{ Geological Excursions round the Isle ‘of Wight, 3rd Ed., p. 98. § T.F. Gibson. Quart. Journ. Geol. Soc., vol. xiv. p. 175, 1858. || Geological Excursions round the Isle of Wieht, 8rd Ed., p. 99. F 56786. B 18 GEOLOGY OF THE ISLE OF WIGHT. CHAPTER III. LOWER GREENSAND OR UPPER NEOCOMIAN. INTRODUCTION. Tuts formation occupies the greater part of the southern or Cretaceous area of the Isle of Wight, and forms important escarp- ments, such as that which runs from Compton Bay by Brook, Mottistone, and Brixton, or the succession of bold shoulders which dominate the upper parts of the Medina and Yar valleys, and on one of which Godshill is situated. But the most complete sections are to be obtained in the four coast-sections of Compton Bay, Atherfield, Shanklin, and Redeliff at the east end of Sandown Bay. At Redcliff the thickness of the Lower Greensand is about 600 feet; at Atherfield it has imercascd to over 800, but at Compton Bay, about 16 miles west of Redeliff, the thickness is reduced to 399 feet. Lastly, at Punfield, 20 miles west of Compton Bay, it is no more than 198 feet. It would seem then that the direction in which the strata thicken most rapidly lies a little east of south. The Lower Greensand of Atherfield was made the subject of the most exhaustive examination by Dr. Fitton in the years 1824-47. The results of his work were embodied in a large number of papers, but chiefly ina paper read before the Geological Society in 1845.* Not only was the thickness at Atherfield found to be greater than elsewhere in the Island, but fossils were very much more abundant. ‘The rich collection made by Dr. Fitton showed that the fauna of the Lower Greensand was both distinct from that of the Upper Cretaceous Rocks above, and possessed nothing in common with the Wealden Shales below, there being in fact a complete paleontological break at the base of the formation. This is the mere noticeable in that the lower beds of the Lower (Greensand are, like the Wealden Shales, of a clayey character. Later observations have shown that this complete contrast in the fauna was caused by an abrupt change in the physical geo- graphy of the area in which the Lower Greensand was distributed, and was preceded by some erosion of the Wealden Beds. The abruptness of the change is indicated by the following evidence:— C) The division of the Lower Greensand from the Wealden Shales is everywhere absolutely sharp, so much so that the two can be cleanly separated by a knife-blade. * Quart. Journ. Geol. Soc., vol. iii. p. 289. 1847. References to his papers will be found in the Bibliography at the end of this book. sa a ae LOWER GREENSAND. 19 (2.) The base of the Lower Greensand is a thin line of coarse grit, containing rolled fragments of fossils (Amnio- nites and other marine forms) which must have been derived from some marine beds, expo-ed outside the limits of the freshwater Wealden Beds, together with a oseasional pebble of sandstone larger in size, and resembling the sandstones which are interstratified in the Wealden Beds, There are also in this grit nunierous broken bones, teeth, and scales of fish, and at Atherfield it contains fragments of Vicurya strombiformis, the gasteropod which is so abundant in the top of the Wealden Shales at this spot. ‘Che fragments oceur only in the grit, which is about three quarters of .an inch thick, and have doubtless been washed out of the sur- face of the Wealden Shales. At Punfield this grit. has yielded a well-rounded pebble of white silicified wood, precisely, similar to the wood in the Lower Purbeck Beds. (3.) The Wealden Shales, where the junction is exposed, often present the appearance of having been disturbed and broken up for a distance of a foot or two below the base of the Lower Greensand. (4.) In Wiltshire the Lower Greensand overlaps the Wealden Beds so rapidly as to indicate an actual unconformity .* As a result of this overlap it passes westwards on the Upper Oolites, a fact which provides a clue to the source of the rolled fossils of marine species, which occur as pebbles at the hase of the Perna Bed in the Isle of Wight. As far as the Isle of Wight is concerned, however, there is not sufficient evidence to establish an unconformity between the Lower Greensand and Wealden Beds. That the bedding of the two is strictly parallel is proved by the persistence of the Wealden Shales at the top of this formation, not only in the Isle of Wight, but both to the east and west on the main-land. The change of sediment is such as might have been produced by the sudden con- version of a partially land-locked estuary or lake into a bay open to the sea, whether by subsidence or by the washing away of a barrier. On this theory we must suppose that a Lower Greensand sea with its proper fauna was in existence at the time when the Wealden Shales were still being deposited in the land-locked area. This supposition is in accordance with the sequence observed in the north of England. For the Upper Neocomian deposits of Yorkshire, as shown by Professor Judd, contain the same fauna as the lowest of the Isle of Wight Neocomian beds, namely, the Atherfield Clay. We are thus compelled to suppose the Middle and Lower * Geology of England and Wales, by H. B. Woodward, 2nd Ed. 1887, pp. 352, 354, 375. B 2 20 GEOLOGY OF THE ISLE OF WIGHT. Neocomian strata of the north to have been contemporaneous with a part of the Wealden Beds of the south, the one having been depo- sited in an area open to the sca, the other in a basin that remained Jand-locked until a later part of the Neocomian period. ‘the history of the great freshwater deposits, of which in the Isle of Wight we have only the upper part, is beyond the scope of this Memoir, and will be treated more fully in the General Memoir on the Cretaceous Rocks. The Lower Grevnsand of the Isle of Wight is divisible into four groups, capable of being traecd throughout. But at Atherfield, where they are most fully developed, Fitton made six principal divisions and sixteen minor sroups. In the following table Fitton’s groups are compared with those adopted in this Memoir, and with those in use in the Weald of Kent and Sussex. The only point in which a material difference between the two classifications exists, occurs in Fitton’s Division I’, A portion of this has now been separated under the name of Oarstone, while the lower part of it is grouped with E., to which it is lithologieally allied, under the name of Sand-rock Series. The lowest member of Fitton’s Group XV., a thick bed of clay, is taken as the top of the Ferruginous Sands, in consequence of the similarity of the deposit to a band of shale which forms the top of the Sandgate Beds at Pulborough.* The Perna Bed, though paleontologically of the greatest interest, is too thin to be separately mapped. The names used have been adopted as far as possible from those who first investigated the beds. The term Shanklin Sands was proposed by Fittont for the whole of the Lower Greensand to avoid confusion between this formation and the Upper Greensand, and was used in this sense by Martin. But subsequently the name became restricted to the upper beds of the Lower Greensand, and having been made to include a varying proportion of the deposit by various authors, and its original meaning, as intended by its author, having been lost, it has been thought better to abandon it. The name Vectine, also proposed by Fitton, and subsequently modified into Vectian by Mr. Jukes-Browne,} has never come into general use. (Sve also p. 2 on the use of Vectian for the Fluvio-Marine Series.) Geological Geological Fitton, 1845, Survey, 1887. Supyey: (Atherfield.) (Isle of Wight.) (S.E. England.) XVI. Various sands and clays Carstone, : Folkestone XV. Upper clays and sandrock Sand-rock Beds. E _ Series, * Geology of the Weald (Geological Survey Memoir 136 t alan. Phil, 2, viii p. 461. neers t Geol. May. tor 1885, p. 208. LOWER GREENSAND. 21 : Geological Geological Fitton, 1845, Survey, 1887. Survey. (Atherfield.) (Isle of Wight.) (8.12. England.) XIV. Ferruginous beds of) — ) Blackgang Chine - , XII, Sands of ve Undercliff - NII, Foliated clay and na XI. Cliff-end sands X. Second Gryphea bed - s Sandgate IX. Walpen on Ladder ap oe. Beds. sands eee Iythe Beds. VIIL. Upper Crioceras group VII. Walpen clay and sands VI. Lower Crioceras group V. Scaphites group IV. Lower Gryphiea bed -) III. The Crackers - CJ Il. The Atherfield Clay - 3B) Atherfield Atherfield I. Perna Mulletibed - A Clay. Clay. These divisions pass one up into the other, without any sharp line of demarcation, except in the case of the Sand-rock Series and the Oarstone. Here the boundary is rather more sharply defined, and can be followed with little difficulty through the central parts of the Island. The Carstone everywhere passes up into the Gault. In describing the Lower Greensand it will be convenient to take the localities in order from west to east as before, commencing with Compton Bay. Compton Bay. The base of the Lower Greensand in Compton Bay is not seen in situ in consequence of a great slip of Atherfield Clay and of the upper Wealden beds described on p. 8, It is not difficult, however, to find among the ruins masses which show the junction as clearly as if it were in place. The following details were noted in a fallen mass -—— Br, In, Atherfield Clay- Clay, mottled red and grey. Caleareous and ferruginous Perna Bed - grit, with Modiolu, &e. - 1 0 Green sandy clay G 2 Wealden Shales - Blue paper-shale, broken up into a breccia for a distance of about 1 foot below the base of the Lower Green- sand - - - 38° O+ 22 GEOLOGY OF THE ISLE OF WIGHT. In every case where the junction was exposed, the same brecciated appearance in the surface of the Wealden Beds was observable, sometimes extending to a depth of 2 feet into the Wealden. There can be little doubt that it indicates that a certain amount of erosion of these beds took place before the Lower Greensand was deposited. In addition to the particles of quartz which give to the Perna Bed its gritty character, there are in it small rolled phosphatic nodules. The Atherfield Clay, excepting the top beds, can be seen only as a flowing mass of pale-blue clay, with phosphatic concretions. Its thickness consequently is difficult to determine, but so far as can be judged it is like the other beds considerably thinner than at Atherfield, and may be estimated at about 60 feet. The succeeding beds are clearly exposed, and are shown in descending order in the following detailed section :— Compton Buy. Carstone, | Brown sand, with 3-inch pebble-band at the base, 6 ft. containing rounded quartzite pebbles up to 4 inch in diameter, some phosphatic pebbles, and many pieces of wood. Cylindrical phosphatic nodules also occur - - - 6 0 ( Blue clay - : - - - 2 6 Pebble-band with quartzites, &c., 0-3 inch =] Grey and greenish sand, with a layer of pyritised wood 83 feet from the top, and scattered frag- \13 0 Sand-rock ments near the top, about 123 feet + - | Series, < Pebble-band, as above, 6 inches - -J 41 ft. G ins. | Bright-yellow sand, with an irony seam at the base - - - - 10 0 Clean white sand and blue clay, interbedded in wavy Jaminz, and giving out copious chaly- 56 O beate springs (‘‘ foliated series ”’) - - Clayey grit, weathering green, with a band of quartzite pebbles, 5 inches thick, at the base - 26 0 White sand like gannister 2-0 Dark sand and clay intermixed, with much vege- table matter in the upper part, and looking like a rootlet-bed* ~ - 3s 10) Band of small quartzite pebbles Oo 3 Sand like gannister - - - - 5 0 Very black and sooty-looking sand or silt 7 8 Lighter do. striped - lo 0 Band of soft yellow rolled phosphatic nodules, with some quartzites - - - O 1f Lighter coloured and striped ‘ sooty ’’ sand, with many small soft yellow phosphate pebbles near the base - - 4 0 “Foliated”” sand and clay as above, passing down into paper-shale - - : 5 8 ; +Very green gritty sand, with hard pale-yellow Ferruginous phosphates, some cylindrical,some rounded - 3 6 Sands, < Brown sandstone < . = 1 2 251 ft. 64 ins. | Green grit as above - i 6 * This and the other dark sands were tested by Mr. C. Tookey for manganese, but found to contain none. The colouring matter appeared to be carbonaceous. + This and {the seven beds following it crop out in the west side of Compton Chine. Its greeu colour is due to un abundance of grains of glauconite. Seep. 255 dor an analysis of a specimen from this hed. LOWER GREENSAND. 23) Fr. In. Brown sandstone - - - - ae Lo Green and grey silty sand, with fucoidal markings 1 0 Brown sandstone - - - 10 Green and grey silty sand, with faboidal markings 2 0 Brown sandstone, with small pebbles and pieces of lignite scattered throughout; an imper- t sistent band of silty sand in the middle - 42 0 Green silty sand, passing down - - = 116 Clay - - . = < =n FO Brown and red grit, made up largely of rounded grains coated by iron oxide; forms the cliff east of Compton Chine - - - 54 0 Yellow sand, much fretted by the weather in the upper part - - = - - 20 0 Pale-green sandy clay, with light-grey nodules containing fossils, and passing down into = 10° 0 Yellow sand, clayey in parts - lo: --O | Grey silty sand, with bands of soft yellow sud: | stone below - - - - Sila LO ee Pale-blue clay with Perna Bed at the base ; esti- 60 ok mated at - - - - - 60 0 399 04 The precise correlation of the beds in this section with those of Atherfield is impossible. As will be seen subsequently, the beds are not only very much thinner, but have changed their RIG ods The Sand-rock Series in Compton Bay. a. Soil and gravel. g. Ochry band. 6. Gault. h, i, k, l. Blue clay and white sand c. Carstone, or ferrugincus grit. interlaminated in varying propor- d. Pebble sand. tions. e. Blue clay and sand, with small pebbles | m. Chiefly sand, throwing ont much and lignite. chalybeate water. jf. Bright yellow sand. n. Very green and gritty clay. 24 GEOLOGY OF THE ISLE OF WIGHT. characters, Fossils are also comparatively scarce in Compton Bay. Dr. Fitton identified a “mass of brownish clay and sand which lies next above the Atherfield Clay, as the Lower Lobster Bed, or the lowest part of the Crackers sub-division of Atherfield, and a prominent portion in the lower part of the brown and red grit as the Lower Gryphwa bed of Atherticld. ; The upper beds present a general resemblance to those which form the upper part of Blackgang Chine, though they are very much thinner, and contain none of the bands of sand-rock wich form so distinctive a feature in that chine. The abundance of water strongly impregnated with sulphate of iron, which issues from them, is 2 noticeable feature. As will be seen, the chalybeate spring near Blackgang issues from the same beds. ‘The annexed wood-cut (Fig. 7) represents the general arrangement and appearance of these upper beds in the cliff. ATHERFIELD. The Lower Greensand here attains a greater development than in any other part of the Isle of Wight, and has yielded a rich suite of fossils. Its thickness has been variously estimated at 808 feet by Dr. Fitton, at 833 feet by Ibbetson and Forbes,* and at 752 feet 11 inches by Mr. Simms. The description of it will be taken from west to cast, that is in ascending order of the strata. The Atherfield Clay and Perna Bed. After leaving Compton Bay the Perna Bed is not seen again till we reach Cowleaze Chine. It is here well exposed under the Fic. 8. Perna Mullett, Desh. * The thickness given by these authors is 843, but the total obtained by adding x .t. Db up the figures given in their table is only 833, Or LOWER GREENSAND. a bridge by which the military road crosses the chine. It re- appears in the top of the cliff 300 yards south of the chine, and slants down thence to the beach 150 yards cast of Atherficid Point, the dip, as calculated from the heights and distances on the Ordnance Map, being 1 in 24, or about 24°. The section of this bed in the cliff is frequently obscured by the slipping of the Atherfield Clay, but is now (1887) admirably exposed 250 yards north-west of the point. Section of the Perna Bed near Atherficld Point. Fr. In. fossils - - - - Se DG Blue fossiliferous clay, based by a gritty seam with phosphatic nodules and fish-remains. Panopea occurs in the clay in the position of growth - - - - = 2 Wealden Shales (see p. 14). Calcareous and ferruginous stone, with many Perna Bed | NI 5 _ The brecciation of the top bed of the Wealden, which has been described at Compton Bay, is not observable here, but the line of demarcation between the blue purely argillaccous shale, with its numerous bands of fresh or brackish water shells, to the rather sandy clay with numerous marine forms, is sutticiently striking. The gritty base of the clay, moreover, points to some erosion having taken place. The grit varies in thickness rapidly, and is sometimes absent. Dr. Fitton, in allusion to it, remarked that “the remains of fishes, chiefly teeth and small fragments of Fic. 9 Exogyra sinuata, Sow. bones, are mixed with coarse quartzose gravel at the bottom of this bed [the Lower Perna Bed]; and occurring thus immediately 26 GEOLOGY OF THE ISLE OF WIGHT. over the Wealden, or even in contact with it, it is not unreason- able to suppose that the fish were killed by the change from fresh water to salt.”* Remains of fishes were identified by Sir Philip Egerton, and a smali Saurian phalanx by Professor Owen. The Perna Bed was so named by Dr. Fitton in consequence of its containing great numbers of Perna Mulleti, Desh. (Fig. 8), which hag not been found in any of the other beds. Fxogyra (Gryphea) sinuata also occurs in abundance and of a large size. The rest of the fossils will be found distinguished in the fossil list on p. 261. The Atherfield Clay, which was also named by Dr. Fitton, is of a pale-blue colour, and, unlike the Wealden Shales, is devoid of lamination; it contains numerous flat concretionary nodules. « Among the fossils the most common in the lower portion is Pinna robinaldina, VOrb. Ammonites are not unfrequent; and the remains of a turtle . . . were obtained here.” (Fitton, op. cit, p. 296.) The thickness of the Atherfiell Clay is about 60 feet, according to Fitton, but 99 feet according to Ibbetson and Forbes, who include the Lower Lobster Bed in the sub- division, The Lower Lobster Bed is an impure fuller’s earth, abounding in remains of JJeyeri (CAstacus), from which fossil it takes its name. It is now grouped with the Atherfield Clay on purely lithological grounds, the natural base of the ferruginous sands which constitute the overlying group occurring above and not below the Lower Lobster Bed. The thickness of the bed is 25 feet 6 inches according to Fitton, 29 feet according to Ibbetson and Forbes. The Ferruginous Sands. This division of the Lower Greensand attnins a thickness at Atherfield of whout 520 feet by Fitton’s measurements, or 5u8 by those of Ibbetson and Forbes. The lowest bed of the group, bed No. 5 of Fitton, and named by him the Crackers, from the noise made by the waves in the shght rocky prominence formed hy the rock, consists of coarse erey or brown sand, about 20 feet in total thickness. It contains two layers of ferruginous and calcareous concretionary masses, abounding in fossils. Some of the masses in the lower layer “are 6 or 7 feet long, and a foot to 18 inches in thickness, and umost composed of Gervillia anceps (ariculoides), with Trigonia dedalea, Ammonites Deshayesti, &e.” (Fitton, op. cit., p- 298.) In the upper laver Dr. Fitton noted coniferous wood bored by Teredo, and in the upper part of the sand, Thetis, a large Astacus, and Ammonites Deshayesi. “In the lower part, great numbers of Panopeua (Myucites) plicatu, Sow. ave found in jt standing * Quart, Journ, Geol, Suc., vol. iii. p. 294 (1847). LOWER GREENSAND. 27 obliquely upwards.” Pinza occurs also in clusters. The promi- nence formed by this rock will be found at the foot of the cliff, 600 yards east of the Coastguard Station. Ite. 10. Panopea plicata, Sow, The overlying set of beds (forming the upper part of Fitton’s Crackers Group, Nos, 6-10) embraces a thickness of about 40 feet. It consists of brown clay, 16 cr 17 feet thick, in the lower part, and of clay mixed with sand in the upper part. The beds are fossiliferous throughout, and are known as the Upper Lobster Beds, from the occurrence in them of remains of Meyeria (Astacus) vectensis. Fia. 11. Gervillia anceps, Desh. Group IV., or the Lower Gryphza [Exogyra] Group of Fitton, has at its base a bed of rust-coloured sand about 21 feet thick. This is overlain by two feet of sand containing Gervillia (Perna) aleformis, tut chiefly remarkable for the great abundance of Terebratula sella, Sow., which, though ranging from the base of the Lower Greensand to the top of the Ferrugimous Sands (Group XIV. of Fitton), is nowhere so numerous as here. 28 GEOLOGY OF THE ISLE OF WIGHT. The bed with Bzogyra sinuata, which Fig. 12. comes to the shore under Atherfield ‘ High Cliff, and forms a reef running Lerebratula sella, Sow out through the beach about 350 yards west of Whale Chine, is next in suc- cession. It is about 10 feet thick, the lower part consisting of brown and reddish sand with spherical grains of oohitic iron-ore, and containing Pinna robinaldina, D’Orb., while the upper part forms the reef in which numerous large Evogyre are conspicuous. Group V., or the Scaphites group of Fitton, has a thickness of 50 feet 4 inches, and may be divided into three beds, the lowest of which is brown and rust-coloured sand about 20 feet thick, and containing large Lxogyra sinuata, Ostrea carinata, &¢., and at the bottom layers of Serpule, Terebratule, &e. Nodules in layers containing Ancyloceras (Scaphites) gigas and A. Hillsii lie next above this sand, and are succeeded in ascending order by about 27 feet of dark-grey sandy clay, with the large Erogyra sinuata, in the upper part. A reef containing conspicuous clusters of Serpule vans out from the cliff at this point. Group VL, or the Lower Crioceras beds, contains several ranges of this fossil, imbedded in sand. The lowest range rises from the beach on the west of Whale Chine; the highest crosses the bottom of the chine. ‘The group is 16 feet 3 inches in thickness. Group VIL, the Walpen clay and sands, consists of a dark-green mud at the bottom, about 27 feet thick, with nodules including Exogyra and Ammonites Martini, and of an upper division, clayey above and sandy below, about 33 feet thick, containing Punopea (Myacites) mandibula, Pinna robinaldina, and a Dentalium. The clay-beds of this group form the undercliff, on to which Ladder Chine opens. They rise from the beach about 200 yards east of the chine, cross Whale Chine, and reach the top of the cliff 700 yards west of Whale Chine. Their position is always marked by the springs they throw out, except close to the east side of Whale Chine. Group VIIL, the Upper Crioceras beds, is 46 feet 2 inches thick, and contains four or more ranges of Crioceras Bowerbankii, with Ammonites Martini, Gervillia solenoides, Tercbratula sella, and Trigonia aleformis (TL. vectiana, Lye). The top bed of the group rises on the east of Walpen Chine, crosses Ladder Chine, and may be seen in the chasm beneath it. The whole group crosses Whale Chine also. Group [X., the Walpen and Ladder sands, consists of greenish and grey sand, about 42 feet thick, with a layer of lenticular masses of dark olive-green stone at the base, containing numerous fossils. About 6 feet higher up is a thin band, consisting for the greater part of Serpule, apparently twisted together, associated with Vercbratula sella and other fossils. LOWER GREENSAND. ty Group X., or the Upper oe eroup, includes about 16 fect* of sand, with some clay. In the lower 12 feet there are sevcral ranges of Hxogyra sinuata, and nodules with Bnallaster (Brissis) and Ammonites Martini. The ferruginous matter of this bed is in some places distinctly oolitic, like that of Group TV. ‘Lhe upper part of the group isa ereenish sand with Evogyr a sinuata, this being the highest point in the Atherfield section which has yielded that species. Small fragments of vegetable remains (Lonchopteris Muntellit) occur not only in_ these beds, but nearly throughout the entire formation. In the lower part of this group they are associated with Inoceramus. Group XL, the Chiff End sands, about 20 feet in thickness, consists of sands with a thin bed of clay with Trigonia dedalea in the lower part, and in the upper part of dark bluish and green sand, with many cylindrical stem-like and branching coner tions, containing pyrites. Group XIL, the Foliated Clay and Sand, consists of thin alter- nations of clean greenish sand, with dark-blue clay, and much pyrites. The bed includes also Jenticular masses of coarse current-bedded sand-rock. Jt is about 25 feet thick, and from its yielding nature forms an extensive undercliff on the west side of Blackgang Chine. But it is most clearly exposed to view on the buttress of rock which forms the south side of \Walpen Chine, where, however, it can be reached from above only. The dip in this part of the section may be calculated by tracing this bed down to the beach. It amounts to 1 in 26, or a trifle over 2”. In general character this group is closely allied to the Sand- rock series, and it was corrclated by Dr. Fitton with a bed which hag been taken as the base of that series at Shanklin. Traced inland this bed passes by Pyle, Corve, and Kingston, cropping out at the foot of a marked feature all the way (jostcu, p. 30), and thence striking westwards seems to die way in beds distinctly of the ferruginous type. Group XIIL., the sands of Walpen Undercliff, is about 97 feet thick. It has at its base a bed of loose white sand or sand-rock, about 10 feet thick, which rises to the top of the cliff on the south side of Walpen Chine. Above this bed, which he calls the First Sand-rock, Dr. Fitton noted the following in descending order :— Fe. Es Light green and yellowish sand, siving a bright. -green streak under the pick - - 25 9 Brown sand with Astarte Beaumont Pian, Pecten, and Terebratula - - - - - 1 6 Moist greensand . - -, - - 12 6 Sand, based by a coarse gravel with pebbles of quartz and Lydian stone - - - - - - 29 8 Above these are brown sands with polished particles of iron-ore, and sands with beds of dark-green or black cohcrent mud. * There are some slight disercpancies in this and othcr cases between the thick- nesses given in the text and in the table of Dr. Fitton’s paper. 30 GeOLOGY OF THE ISLE OF WIGHT. Group XIV., the Ferruginous heds of Blackgang Chine, forms the upward limit of the fossiliferous beds of the Lower Green- sand. The beds appeur above the shore at a point 600 yards north-west of Rocken ind, and form a vertical foot to the cliff as far as Blackgany Chine. Here the undercliff formed by Groups XII. and XIII. commences, and the harder beds of Group XIV., rising slowly in the cliff, form a step between this undercliff and a similar feature formed above by Group XV. The cascade in the lower part of Blackgane Chine, which was ascertained by Fitton to be 91 feet in height, is caused by the comparative hard- ness of the ferruginous bands of Group XIV. This group crops out in the top of the cliff on the south side of Walpen Chine, and strikes thence in a bold escarpment throueh Pyle, Corve, and Kingston. The details of the group are given by Dr. Fitton as below :— Ferruginous Bunds of Blackgung Chine. Ferruginous concretions, immediately above the cascade 1 Brown and yellow sand - 7 5 ae SFP a) Ferruginous concretions, with many vacant moulds of fossils, most abundant near Walpen High-Cliff : 1 Sand, with fossils = - - 7 90 Ferruginous sand-rock, with fossils 5 The species found in this group can be identified in several cases with those of the Perna Bed, at the very bottom of the Lower Greensand. Among them may be named Panopou plicata, Sow., P. nevcomiensis, D’Orb., Corbula striatula, Sow., Thetis minor, Sow., Trigouia caulata, Ag., Pinna robinuldina, D’Orb., &e. The next overlying bed, forming the lower member of Fitton’s Group XV., isa great mass of clay, between 35 and 40 feet thick, It occupies the shore for a distance of 350 yards, first rising into sight near a waterfall 200 yards north of Rocken End. It forms a step in the cliff as far as Blackgang Chine, where it widens out into an undercliff. The most convenient place for examining it will be found from 560 to 600 yards west of Cliff Terrace, near the top of the cliff, where the shale of which the bed largely consists has been cut back by wind and rain into a broad shelf, entirely bare of vegetation. This bed forms the top of the great division of the Lower Greensand, which we have named the Ferruginous Sands. The Sund-roch Series, This series, like the other beds of the Lower Greensand, attains its greatest development in the southern part of the Island, its thickness being 186 feet by Fitton’s measurements, or 208 by those of Ibbetson and Forbes, while at Compton Bay it amounted to 814 feet only. Here also it contains in their typical form those beds of slightly coherent white or yellow quartz sand, LOWER GREENSAND. 31 which form so conspicuous a feature in the upper part of Black- gang Chine, and to which the name sand-rock is singularly applicable. Three distinct bands of this deposit occur, namely, the beds referred to by Fitton as the fourth, third, and second sand- rock. The second or lowest occupies the beach from Rocken ind for a distance of 200 yards northwards ; but is partly concealed by slips of Chalk and Greensand. ‘Thence it may be traced continuously to the top of the cliff 500 yards west of Cliff Terrace, where it is seen overlying the great ciay-bed previously described. The third or middle bed, and the fourth at the top of the series, may be traced from the chalybeate spring to a point on the east side of Cliff Terrace, where they reach the top of the cliff. The following descending section of the serics was made in the neighbourh od of the chalybeate spring, 600 yards south-east of Southland [louse :— Section of the Sand-rock Series near the Chalybeate Spring. Carstone (for details, see p. 57). Fr. Grey sand with wood, large concretions, and seams of clay; a line of quartz pebbles at the base - - - 20 Grey and yellow sand interlaminated with clay - 7 Current-bedded yellow sand-rock, with wood; thins away southwards (4th sand-rock of Fitton) - - i Laminated sand and clay, with wood; throws out the chaly- beate spring - - : oe A variable bed; contains clay with partings of sand, some- times nearly all sand, and passes down into - 16 White sand-rock (3rd sand-rock of Fitton) about - => 0H) Variable sand and clay, with a line of nodules about the middle - - - - 60 White sand-rock (2nd sand-rock of Fitton) - 2 184 The interlaminated sands and clays in this section are identical in character with the “foliated bed ” 56 feet thick of the Compton Bay section (pp.22, 23), and like it throw out chalybeate water, derived doubtless from the decomposition of iron pyrites. The Chalybeate or Sand-rock Spring was first noticed about the year 1800. It was found to flow at the rate of 100 to 150 gallons a day, and gave the following analysis* :— 16 ounces yielded :-— Carbonic acid gas, 3 cubic inches. Solid ingredients, dried at 180°, 80°5 grains. GRAINS. Sulphate of iron - - 41-4 Sulphate of alumina 31°6 Sulphate of lime, dried at 160° - 1-1 Sulphate of magnesia - - 3°6 Sulphate of soda - 16°0 Chloride of sodium 4:0 Silica - - = - - oy 107°4 Temperature, 51°. Specific gravity, 10075. * Dr. Marcet, Trans. Geol. Soc., Ser. 1, vol. i. p. 213. 1811. vs nN GEOLOGY OF THE ISLE OF WIGHT. From the chalybeate spring eastwards the Sand-rock series is alinost entirely concealed }y the slipped Greensand and Chalk of the Undereliff. The upper beds of the series are seen in a hold bluff between Rocken End aad Knowles, and again in the lower part of the cliff below Niton. ere a white sandstone also is exposed above the beach, about 100 feet below, which seems to be the third sand-rock of Fitton. The last exposure occurs in Binnel Bay, where interlaminated sands and clays are exposed at the base of the cliff. From this pint eastwards there 1s no rock seen in place till we reach Monk’s Bay at Bonchureh. The description of the Carstone or uppermost sub-division of the Lower Greensand of this neighbourhood will be found on pp. 57, 58. SANDOWN TO BoNCcHURCH. The Atherfiel! Clay and Ferruginons Sonids. Though nearly the whole of the Lower Greensand is exposed in this coast section, the beds are not so conveniently situated for examination as at .\therfield, and have yielded far fewer fossils, The Perna Bed and Atherfield Clay rise from the beach near Sandown Pier in a low cliff, but are concealed by buildings ; nor is the former exposed now at low water, as seems formerly to have been the case. The overlying beds consist of green grey and brown sands, so far decomposed as to render the identifi- cation of the eroups of Atherfield impossible. But specimens of Crioceras were tound by Captain Ibbetson in a quarry, not now identifiable, near the shore between Small Hope Chine (the north end of Shanklin sea-wall) and the Barrack Ill, Sandown. The horizon would scem to correspond approximately with that of the Crioceras ranges of Whale Chine. Some of the sands north of Little Stairs Point are very dark-coloured, and contain small fragments of wood impregnated with pyrites. At Little Stairs Point 2 fault is clearly exposed, a rare circum- stance in the Isle of Wight. The fanlt ranges about west-north- west, and throws the beds down to the south. Soon after passing this fault the beds assume a horizontal position, or nearly so and we meet with the first marked bed in the section. It consists of ferruginous sandstone, studded with clusters of Exogyra sinuutu and Ostrea frous (= O. prionotc,) and identified by Fitton (op. ae p- 317), with part of his Second Grypheea Group X. Above it occurs a bed composed of alternations of dark slaty clay with greenish sand, which Fitton recoenised as his Group XI At the top of the cliff is an iron sand. Chalybeate water issues from these strata. The spring known as Shanklin Chalybeate Spa was first noticed by De. Pensee physician to Charles If. It hax een analysed by Dr. A. is Hassall with the following result — ; et” LOWER GREENSAND. 33 Chalybeute Spa, Shanklin Esplanade. Chemical Composition. Combined as follows :— GRAINS. Total residue - 28°46 per gallon. Carbonate of lime - 7°66 Lime - 5°64 55 +5 magnesia - 2°35 Magnesia 1°90 es a3 protoxide of Potash - 0°25 - iron 213 Soda - - 20) 3 Sulphate of lime - - 3°28 Sulphuric acid - 2°81 ss $4 magnesia - 1°32 Chlorine - 3°23 55 Chloride of potassium - 0°40 Tron - - 1°03 3 i sodium - 3°04 Silica - - 1°40 55 53 magnesium 0°85 Nitrogen as nitrates Silica - - - 1°40 and nitrites = Volatile and combustible Free ammonia - — matter - - - 0:14 Organic nitrogen 0°01 e Hardness, 9°30. The horizontality of the beds (excepting in a very gentle anticline south of Little Stairs fault) is maintained as far as Shanklin Chine. Here a south-south-westerly dip sets in, which gradually brings the upper strata down to the beach in succession, the anyle of dip, as calculated from the heights on the Ordnance Map, «nounting to 1 in 30, or a trifle less than 2°. The strata last described contain oolitic iron ore, and are identified by Fitton with a part of his Group XIII. They sink below the beach on the south of Shanklin Chine, and are succeeded upwards at a few feet distance by a richly fossiliferous bed, in which Fitton obtained Vermécularia, Serpula, Waldheimia (Terebratula) pseudgjurensis, Leym., T. sellu, Sow., Rhynchonella suleata, Park. (T. multiformis, Fitton), Rhynchonella gibbsiana, Sow. (TZ. gébbsianu, Fitton), and Anomia, Exogyra, Pecten, Limu, &c. Ten feet and eighteen and a half feet higher up respectively are two ranges of Exogyra sinuata, first discovered by Captain Ibbetson.* Next above these lies the sandstone which forms a reef called Horseledge by Fitton, and which yields ferruginous nodules with Panopea plicata, Sow., Trigonia aleformis, Park., Thetis minor, Sow., Gervillia anceps, Desh., Terebratula sella, Sow., Rostellaria vobinaldina, D’Orb. This was said by Fitton to resemble his Group XIV. A. clay-band, 8 feet thick, which rises from the beach about 300 yards north of Luccomb Chine, corresponds to the thick clay which lies next above the cascade in Blackgang Chine (the lower part of Group XV. of Fitton). It makes a small undercliff or ledge in the cliff, and crops out 300 yards south of Shanklin Chine, whence it may be traced through the brick pit at Lower Hide, by Apse Farm, to the brick pit, now disused, at Sandford. ‘This band forms the top of the Ferruginous Sands. * Rep. Brit. Assoc. for 1844 (Sections), p. 43. { This scems to be the reef marked Yellow Ledge on the Six-Inch Ordnance Map, and is about 350 yards south of the reef marked as Horse Ledge. E 56786. C 34 GEOLOGY OF THE ISLE OF WIGHT. It will be noticed that the fossiliferous sroup described above corresponds to beds at Blackgang, in which only a few. fossil= occur. On the other hand, the strata between Little Stairs and Sandown, though corresponding to richly fossiliferous beds at Blackgang, have yielded no fossils. These differences are princi- pally due to the condition of the rock. Fozsils are seldom pre- served in any part of the series near the surface of the ground, but only in the deep-seated strata that are exposed at the foot of the cliffs, and the weathering of the beds, which has reached a depth varying according to local circumstances, has extended below the level exposed in the Sandown cliffs. This weathering consists chiefly in the replacement of carbonate of lime by car- bonate of iron, and the conversion of the latter into peroxide of iron, the effect being to destroy the coherence of the rock and to impart to it a brown colour. The original condition of the rock was probably that of the hard greyish and calcareous concretions, in which alone fossils are found in perfection, even at Atherfield. The Sand-rochk Series. This division is finely exposed in the cliffs from Bonchurch to Knock Cliff. Its base is very clearly marked by the ledge or undercliff formed by the clay last described. “A second, but smaller ledge, is formed by a bed of very green clayey grit, at times more clay than grit, which lies about 20 feet higher up. A descending section is as follows :— Sand-rock Series at Luccomb und Knock Chiff. Carstone (p. 59). Fr, ( Bright yellow and white sand with lamins of blue clay in planes of current-bedding. A few bands of very green sand throwing Sand-rock Series < a chalybeate water : - 35 hite and grey sand - - 50 Very green clayey grit, forming a ledge in the cliff, and throwing out water 8 | White and ashy grey sand and sand-rock 20 Ferruginous Sand, &c. 113 The lower part of the series may be most conveniently studied at the top of Knock Cliff, and in Luccomb Chine. The upper beds are accessible in the cliff between Luccomh and Bonchurch, the last exposure being in Monk’s Bay. The inland sections of these beds in the neighbourhood of Shanklin are unusually eood, and will be described subsequently (p. 46). = SANDOWN TO CULVER CLIFF, The position of the base of the Lower Greensand is marked here as in Compton Bay by a great founder of the cliff, and at the LOWER GREENSAND. 35 present time (1887) the junction is easily accessible throughout the greater part of the hollow from which the slip has taken place. The section of the Perna Bed is similar to those which have been described before. The base line of the Lower Greensand is sharp and definite, the lower beds are conglomeratic, and the surface of the Wealden Shales shows signs of disturbance and_ slight erosion. Lastly, the fossils characteristic of each formation are found close up to, but never transgressing the boundary. The Perna Bed is not only visible in the cliff, but reappears in the foreshore below Redcliff Foot, and forms a long straight reef running out to sea a little south of east. Southwards from the slip caused by the Atherfield Clay, the cliff consists of ferruginous sands and becomes mural, continuing so until the softer beds of the Sand-rock series are reached. On the yellow and white sands and blue clays of this series there rests a great thickness of Carstone, which passes up into the Gault. A small fault crosses the cliff at an oblique angle at this point, running W.30°N., and throwing the beds down to the north. It is best seen in the base of the Carstone, which it crusses about half way up the cliff. The Gault forms a small gully descending the clitf obliquely, and occupied by a footpath. This formed a convenient starting point for the following section :— Section of the Lower Greensand at Redcliff: Fr, In. Gault, blue micaceous clay passing down into (Brown clayey grit, becoming more sandy below; small scattered pebbles, and a line of pale phosphatic concretions made up of grit and grains of iron oxide 9 feet from Carstone, theta” s eS #9 t%. Vins. 4 Pebbly band, with anil quartzites 7 (0 6 eel Brown sand with many scattered quartzite pebbles, and phosphatic concretions as above at several horizons, Wavy lines of iron oxide, and some beds with many grains of oxide - - - - 60 0 | Loose brown sand and grit - = 2.) White sand and blue clay interlaminated - 12 0 Do. — with occasional lines of blue clay 32 0 Striped sand and clay = - 9 0 Sunil -roek Series, Do. ehielly clay and very ; base uncertain, sulphury - 4 if rout Wah, Glas: Seam of iron oxide - 0 Bright-yellow and white sand, with ferru- ginous band at base - 31 0 Grey striped sand and clay 2 0 | White sand - 3°40 (Blue and striped candy clay (P=40 feet clay of Blackgang) 21 Hard brown sandstone - 3 6 Grey sand, “* soot-coloured ” - - 6 0 Pebbly bands, containing small guartzites, phosphates, “and iron oxide - or 30) C2 36 GEOLOGY OF THE ISLE OF WIGILT. Fr. In. | Dark-green or bluish clay and sand - - 1 0 Ferruginous pebbly band with small phos- i phates and pebbles of iron oxide - 1 6 Soft yellow sand - - - 6 6 Dark clayey sand - - 6 9 Pebbly band, containing many rolled phos- phatic casts of ammonites and bivalves a4 Pale-brown ferruginous sand - - - 3 0 Pebbly band, with small quartzite and numerous flakes of iron oxide oe Oh Pale-brown sand with flakes of iron oxide - 11 9 Brown pebbly grit with small quartzites and grains and flakes of iron oxide = 24 0 Loose pale-green sand - 17 9 Greenish grit with many wavy seams of iron FerruginousSands, 2 oxide - - - : 3.0 about 367 ft. 6ins.) Brown and green gritty sand 3°40 Dark-green or nearly black clayey sand - 6 0 Brown sand with flakes and grains of iron oxide - : 680 Greensand, with a vivid green streak ; lines of clay occasionally ; a layer of broken oysters 9 tt. from the base. Forms a smooth vertical wall . Z =: 160-0 Brown and reddish brown sandstone with erains of iron oxide very abundant about 2) feet from the top; forms the cliff on which Redcliff Fort stands - 114 0 Green sandy clay with wood and a line of large nodules - ee et) Fine and very clayey sand with wood; lines of nodules in the upper part, and veins of iron oxide - : - - - 4 0 Seam of brown iron oxide 0 5 Fine grey clayey sand - 20 Band of blood-red iron oxide oO 1 Fine grey clayey sand - 10 0 | Fine white clayey sand 20 Pale-blue clay with pale-blue nodules, weathering brown - - =p 0 Calcareous and ferruginous grit with | many fossils, 1 ft. 6 ins. to - 2. 10) oo Passing down into pale-blue sandy Atherfield Clay, 2 a clay with fossils = - - 3 6 83 ft. 4 ims. ie tis d Impersistent grit, with scales and Se | bones of fish and phosphatic pebbles, fe i some of which are rolled ammonites | and bivalves ; about : 0 3 | Pale-blue sandy clay with fossils - 0 6 L LGrit, as above % ~ ©O O}—1 617 1 It will be observed from this section that the thickening of the Carstone, which was noted between Compton Bay and Blackgang, and still more between Blackgang and Shanklin, is still progressing in an easterly direction. The Sand-rock Series and Ferruginous Sands on the contrary, as previously noted, thicken in a southerly direction. In the series of comparative sections forming Plate III. these differences are clearly presented. : LOWER GREENSAND. 37 The occurrence of a band of rolled phosphatic nodules in the upper part of the Ferruginous Sands has attracted the attention of several observers.* The nodules seem to be on the same horizon as those noted at Compton Bay, but in the « coprolite bed” + inches thick at Redcliff, are larger, harder, and better preserved. Among the specimens Mr. Keeping identified Ammonites biples, Sow., 4. cordatus, Sow., Pleurotomaria sp., Curdium striatuluim ? Lucina sp., Myueites sp., Cytherea rugosa? Area contract, Phill, all being fragmentary and much rolled. There occurred also quartzite and other pebbles, as large as walnuts. Up to the present this bed has not been discovered near Shanklin or at Blackgang, nor is its horizon marked by any break in the sequence of the strata. It was probably a near-shore deposit, and did not extend southwards in the direction in which presumably the deeper portions of the Lower Greensand sea lay. Near Godalming, on the contrary, itis largely developed according to Mr. Meyer, who describes it as resting ou an apparently eroded surface of the sands beneath, and as constituting a well-marked basement- bed to an upper division of the Lower Greensand (op. cit., p. 10). Punrietp Cove. Before quitting the description of these fine cliff sections of the Lower Greensand, we will briefly notice the sequence of beds in Puntield Cove. Lying 20 miles west of the Isle of Wight, this locality gives further opportunity of observing the changes in the strata which we have already seen in progress within the limits of the Island. The section of the Lower Greensand in Puntield Cove is as follows. (See also Plate IIL.) :— Fr. In. Gault. ; Carstone, seen only in lumps lying about; apparently about 0 4 { Yellow sand, not well seen, about : : - 10 0 Very sandy dark clay with selenite (perhaps the Zz | thick clay of Blackgang) 2 15 0 & a | White sandstone with white quartz pebbles 20 0 3G 2g Brown sandstone, and yellow sandstone with shales 15 0 Si 2 .© | Interlaminated sands and clays, the latter traversed Que by pnumbers of small tubes filled with sand aeT (? worm-burrows) Lee - 15 0 2% 3 | Ferruginous sand and hard sandstone with Leda 12 0 ‘aa | Interlaminated sands and clays with some thicker BA =p bands of yellow and white sand : 61 0 s Limestone with wavy seams of lignite and many fossils (the ‘“‘ Marine Bed” of Professor Judd), lL variable, but about 0 10 * Meyer, On the Lower Greensand of Godalming. (Geologist’s Assoc.), 1869. Woods, Geol. Mag. for 1887, p. 46. 38 GEOLOGY OF THE ISLE OF WIGHT. Fr. In ( Reddish clay, becoming pale-blue below, very fos- siliferous in the lower part - - 28 0 ~ . | Soft yellow sandstone, with a few fossils - 1 O 22! Pale-red clay, biuish in parts, a few fossils x 6 ~s | Fone bands of very hard grey sandstone; ne fussils 2 9 co-* + Red clay, a few fossils in the lower part _ - «= 6 4) ae ss Dark-green sand, with small pebbles oo and grit, many fossils - - 1 oO 22) Poe Bed Pale-blue sandy clay with many small pebbles (rolled bivalves, Ammonites, &c.), and larger pebbles of sandstone, wood, &c., at base; many fossils - 2 G6 Wealden Shales (see p. ‘)). -_- Tox 5 The lumps of Carstone contain many pebbles, up to half an inch in length. Tts thinness is in accordance with what has been indicated in the Isle of Wight, where it thins from about 70 feet at Sandown to 30 feet near Bonchurch, to 12 feet near Blackgang, and to 6 feet in Compton Bav. The Sand-rock Series is not easily distinguished unless the dark clay with selenite, 15 feet thick, be taken as the represen- tative of the thick clay of Blackgang Chine (35-40 feet thick), A large part of the Ferruginous Sands has assumed a character which in the eastern part of the Isle of Wight is seen only in the Sand-rock Series, namely, that of interlaminated white sand and blue clay (the “foliated sands and clays” of Fitton). In Compton Bay this change is foreshadowed by the appearance of thin beds of this type, interstratified with ferruginous sands considerably below the base of the Sand-rock Satay. : The very forsiliferous limestone, 10 inches thick, corresponds in position with the Crackers, the most fossiliterous zone in the Atherfield section. The Atherfield Clay presents no unusual features, except that there are beds of sandstone at two horizons in it. The recoc- nition of the Perna Bed, and of the usual sharply defined line dividing it from the Wealden Shales, was a satisfactory point. The rolled phosphatic pebbles in the Perna Bed are slichtly larger and more abundant at Puntield than in the Isle of Wie. and more frequently recognisable as the casts of bivalves and Ammonites. This, as well as the changes in the overlying beds indicates that in working westwards we approach the old shore line of the Lower Greensand sea. The fossils in the following list, except where otherwise noted were collected for the Survey by John Rhodes, and have bec identified by Messrs. G. Sharman and E. T. Newton The specimens marked thus “ are inserted on the streneth of their having been recorded from the “ Marine Bands of Punticld eae Prof. judd in the Qywart, Journ. Geol. Sor, vol, xxvii. p aie, Those marked } we added on the authoriiy of Mr, Me a iid, vol. xxviii. p. 252 and vol. xxix. p. 73. : pone LOWER GREENSAND. 39 Fossils from the Lower Greensand of Punfield, The Atherfield Cluy and the limestone above it. Wood. Crustacean, fragment. *Serpula. +Terebratula sella, Sow. tAnomia levigata, Sow. by the Survey also). +Arca cornueliana, D’Ord. * 4, cymodyce, H. Coquand (young). + ¥, Raulini, Leym. (collected » Sp. *+Astarte, sp. +Cardita neocomiensis, D’Orb. +Cardium (Arca) Austeni, Forbes. ep, impressum, Desh. a subhillanum?, Leym. (collected by the Survey also). Corbula striatula ?, Sow. + 55 Sp. +Cyprina, sp. +Cytherea parva, Sow. 7 {Exogyra Boussingaultii, D’Orb. ep, sinuata, Sow. a tombeckiana, D’ Orb. *Tsocardia nasuta, H. Coq. aa SP: *Leda scaphoides, P. and C. Lima, sp. +Lucina, sp. *Modiola giffreana, P. and R. + 4, simplex, Leym. *Orthostoma Verneuili, Vil. +Ostrea Leymerii, D’Orb. +Panopaa neocomiensis, Leym. + ,, Prevosti, Leym. » sp. (=P. plicata, var. of Atherfield). +Pecten (Neithia) neocomiensis, D’ Orb. Fo es $s robinaldinus, D’Orb. t oo» % s p- ,, (very small). * Perna rauliniana, P. and R, *+Pholadomya semicostata, Ag. 6 sp. *+Plicatula asperrima, D’Orb. ee carteroniana, D’Orb. +Solecurtus Warburtoni, Forbes. *Tellina? gibba, H. Coq. Pe sy vectiana, Forbes. +Thetis laevigata, D’Orb. +Trigonia (Atherfield sp.). + Venus, sp. *Actzonella oliviformis, H. Coq. *Actzeon Hsquere, De Verneuil and De Loriere. * 4, pradoana, De V. and De I. *Cerithium Pailleti, De V. and De L. * Qs Vilanoves, De V.and De L. *Fusus? neocomiensis, D’Orb. pean laevigata, Desh. », pradoana, Vil. achat minima, De V.and De Ih. *Pleurotoma Utriliasi, De V. and De L. *Trochus Esquerw, De V. and De L. *Turritella Tournali, H. Coq. ee Lujani, De V. and Coll. » pizquetana, Vil. (collected by the Survey also). * 4, Pradoi, De V. and De L. Ammonites Deshaysii, Leym. *Lamna (teeth). *Pycnodus (teeth). A band of soft sandstone in the Atherfield Clay. Arca Raulini, Leym. Exogyra, sp. Panopzea plicata, Sow. Solecurtus (cast of). The Perna Bed, Multizonopora rimosa, D’ Orb. Arca corneueliana ?, D’Orb. » Raulini, D’ Orb. Astarte, sp. Avicula depressa, Forbes. Cardita fenestrata, Forbes. Cardium subhillanum, Leym. Cypricardia undulata ?, D’Orb. Exogyra subplicata, Rim. Lima lingua ?, Forbes. + SP. Lucina, sp. Panopea plicata, Sow. Pecten interstriatus ?, Leym. P. quinquecostatus, Sow. Tellina, sp. 40 GEOLOGY OF THE ISLE OF WIGIIT. CHAPTER IV. LOWER GREENSAND—coutinued. INLAND SECTIONS. (1.) ALone THE CrenTRAL Downs. The Atherfield Clay. No section of any importance occurs in this division away from the coast, and the tracing of a base-line has consequently been a matter of some difficulty The clue to the position of the boundary is provided by the topographical feature and change of soil produced by the Ferruginous Sands above. The Ferruginous Sands and Sand-rock Series. These two groups will be conveniently taken together in de- scription, As previously remarked, they pass one into the other. Commencing our description on the west, we find the Ferruginous Sands rising into a characteristic escarpment, slightly lower than the Chalk Downs, which runs eastward from Compton Bay on the north side of Brook, Mottistone, and Brixton. The higher part of the ridge is formed by the iron-sand which comes down to the beach on the west side of Compton Chine. The more massive iron-sand which forms the cliff on the east side of Compton Chine crops out in the soutkern slope of the hill, and gives rise to the terrace of deep-red sand on which Brook Church stands. The position of the Sand-rock Series is marked by the abundance of white sand in the soil. At Mottistone a ravine has been cut through the Ferruginous Sands. The top of the Atherfield Clay seems to occur at the Church. he clay 3s overlain by a great thickness of ferruginous clayey sands with a marked bed of brown iron-sand, which seems to be the same as that on the east side of Compton Chine. At the top of the ravine the following descending section may be traced in beds which form the passage between the Sand-rock Series and the Ferruginous Sands :— Near the Long Stone, Mottistone. White sand, about - é ee Tronstone * é ‘ - = fis Grey and “sooty ” silt and sand « - 1s” Grey silt - - - “ 6 Red clay, grit, and sand - Z - 10 Ferruginous grit - - % 4 9 Dark “sooty ” silt - - 12 Ferruginous grits, &c. LOWER GREENSAND. 41 These beds are seen again, but less clearly, in the Inne to Calbourne by Black Barrow, this hill itself being composed of very fine white and grey sand of the Sand-rock Series. But tie best section occurs by the road-side at Rock. ‘Phere the Sand- rock Series consists of current-bedded crimson, pink, brown, buff, yellow, and whitish sand; a beautiful combination of colours, the crimson being very rich. Above this sand lies a band of pebbly iron-stone constituting the base of the Carstone. The Lower Greensand escarpment is breached at Rock by the stream from Bottlehole Spring, but rises again on the east of this valley into a bold hill, many of the lanes up which provide good sections. The upper boundary of the Atherfield Clay -eems to run along the upper road in Brixton, aud the strata next above it consist of yellow sandstone, brown or reddish in places, and with a few thin clayey bands. At the foot of the steeper and unculti- vated part of the hili there runs a bed of deep-red iron-sand with abundant spherical grains of iron-oxide as well as rounded quartz grains, which seems to be the same bed that extends from the east of Compton Chine under Brook Church. Immediately over it lies a bed of yellow and white sand, with wavy lamine of clay, closely resembling the Sand-rock Series. This series, however, comes on nearer the top of the hill, where bright-pink, pale-red, yellow and white sand-rock is repeatedly exposed. The escarpment becomes insignificant south of Shorwell, where it is crossed by the stream from which this village takes its name. Yafford stands on the Atherfield Clay, but a slight rise in the ground, and the brown sandy soil indicate the base of the Ferru- ginous Sands, and show that the strike has changed to nearly south. Near Yafford Mill, a pit shows buff sand and loam overlain by a little gravel, and at Wolverton iron-sand rests on greensand, the dip being north-north-east at 10°. The Shorwell and Atherfield road-cutting near this farm is made through brown and green current-bedded sand at a slightly higher horizon ; while at Haslett brown sand appears with bands of ferruginous grit, and in the upper part a band of white sand. It is difficult to detect here the horizon of the iron-sand which we traced as far as Brixton. It might be expected to run near Woiverton, and through Smallmoor, connecting itself there with a well-defined bed which we shall subsequently follow up from near Blackgang. The sections in the Sand-rock Series are more numerous. The beds of rock, which become a noticeable feature above Brixton, increase in number and thickness eastwards, and form small features along the strike near West Court and Presford. They are generally white, though tinged here and there with red or yellow. So abundant is the white sand soil on these strata that some of the fields on the east side of Bucks had the appearance of being partly covered with snow in the dry summer of 1887. The dip of the rocks in this neighbourhood has diminished to 8°, and grows less as we proceed eastwards. The various sub- divisions accordingly each occupy a wider belt, and at the same time display more fully their characteristic features in the form of 42 GEOLOGY OF THE ISLE OF WIGHT. the ground. The Ferruginous Sands stretch away in a broken table-land to the cliffs of Atherfield and to the southern hills of the Island. The Sand-reck Beds form a series of rounded hills, capped by the Carstone, and fringing the more continuous escarp- ments formed by the Chert Beds of the Upper Greensand and by the Chaik, while a belt of ground, characterised by its gentle slopes and generally by its comparative lowness, marks the position of the Gault. These features are all well displayed in the valley followed by the Chillerton road near Billingham. The best section in the Sand-rock Series occurs by that road-side ; the Ferruginous Sands are well exposed in the road-cuttings at Kingston. Near Cridmore the upper part of the Ferruginous Sands con- tains beds of bright-yellow and white sand, much like the Sand- rock Series, and making it difficult to decide on a boundary line. After passing the \ledina, however, the base of the Sand-rock Series is marked by a bed of coarse white quartz-grit. The bed is seen south of the Star Inn and near Upper Yard, but more clearly in a small pit, 300 yards north-west of Birchmore. There, and in the road-cutting close by, it may be described as a fine gravel, su large are the grains of quartz. The sands above this bed are seen in a pit south of Pagham; they are white and current-bedded with lenticular ferruginous beds. The few sections in the beds below show brown and yellow ferruginous sands, The next section occurs in the Sand-rock Series in the lane runuing east from Blackwater Station. Here white sand and sand-rock were formerly dug. The base of the series is marked by springs and other indications of clay-beds. The same beds are repeatedly exposed in the lanes about Marvel, and are now being dug in a large sand-pit in Marvel Wood, where the followine section is exposed :— r Marvel Wood Sand-pit. : : rer. Carstone ; a ferruginous grit, cemented irregularly in bands by iron-oxide; some of the lower beds contain small pebbles. ‘Top not seen. - - - - 2 ( Grey sand with fragments of clay, with the ap- aevdveule pearance of being a reconstructed bed (sce unis also p. 56), resting on the edges of the cur- rrr rent-bedding planes of i 2 13 White sand with lines of blue clay Z - 30+ 45 — The strata dip, so far as can be judged, to the south-west at a ecntle angie; but a few yards further on rapidly roll over and plunge down to the north. From this point eastwards the serics runs in a narrow belt neer and parallel to the central Downs of the Tsland. ‘I'he centre of the anticlinal axis described above seems to LOWER GREENSAND. 43 strike nearly east from Little Whitcombe to the north side of Marvel Farm, and thence towards Torringford, where further evidence of its position may be seen, A large sand-pit at Standen provides the following section of the Sand-rock Series :— Standen Sand-pit. Fr. In. Green and grey sand, suneni-badiest - 12 0 Yellow sand-rock - 20 Tronstone with a few small pebbles - - 0 6 Yellow and grey loamy sand and lay - - 10 0 Dark-blue clay - 15 0 Ironstone, about - - 0 6 Grey pebbly sand, passing domi - - 6 @ Loose yellow and white grit 12. 0 Fine sand - - - - 8 0 Clay-bed - 0 6 Fine white sand-rock - - 9 O+ 75 6 The bottom of the pit is probably about 15 or 20 feet above the base of the Sand-rock Series, but a considerable thickness of beds, consisting in part of fine-grained buff and brown sand, occurs in the hill-side above, before we reach the base of the Carstone. The dark-blue clay may be the upper of the two clays secn near Shanklin, but correlation in so variable a series is mere guess- work, Almost the only section of the Ferruginous Sands in the Black- water valley occurs in the road-side near Stone, where green an‘ ferruginous sand and deep-brown sand with many grains of iron oxide, are exposed, Similar sands extend along the southern slopes of St. George's Down. On the north side of the Down, 300 yards south of Garrett’s, a sand-pit has been opened near the top of the Ferruginous Sands; the beds exposed are dull-green sands with lines of soft concretions, and are traversed by several small faults, which run nearly east and west, and throw the beds down a foot or two to the south. The dip is northwards at 23°. The next sections occur near Arreton and Merston. A road- cutting south-west of the former place exposes red sand containing many grains of iron oxide, the dip being north-east at 13°, while 300 yards north of Mezston Cross pale sand is seen, dipping south-south-west at 7°. Here then we have the continuation of the anticlinal axis, which we noticed at Marvel. Obscure casts of fossils occur in a band of ironstone on the road to Merston, 600 yards south-west of Arreton Church. At Redway and near Horringford Station red and brown irony sand may be seen, the latter locality yielding specimens of Venus and other fossils according to Mr. Norman.” Apparently the same beds are exposed in the road in Neweliurch. Here and * A Popular Guide to the Geology of the Isle of Wight, p.56. (1887.) 44 GEOLOGY OF THE ISLE OF WiIGILT. wherever elsewhere visible, namely, east of Wackland, and on Skinner’: Hill, they are nearly horizontal, but the Sand-rock Series, on the other hand, near Heasley Lodge dips north at 20°, The anticlinal axis therefore mnst run nearly along (or a little north of) the River Yar at Newchurch. At Knighton a little irregularity occurs in the trend of the great central axis of the Island, in consequence of which the Lower Greensand dips at a more gentle angle, and the characteristic features of its subdivisions are better shown. The Sand-rock Series is seen in a deep lane and pit, 400 yards east of Knighton Mill, and in many spots around Kern, as a brown, red and white sand, while above it the Carstone makes a fairly pro- nounced feature. Good exposures of the Ferruginous Sands occur about Alverstone Farm and on the road to Brading. At the former place, grey and green sand passes under red and brown sand, with many grains of iron oxide. The dip is westerly at 5°-10°, but sweeps round to north at 21° at Adgestone. Here then we fix another point on the line of the Marvel .Anticline, and join it on to the fold which brings up the Wealden Beds of Sandown Bay. The dip of all the strata increases, and their outcrops become proportionately narrow near Yarbridge. A pit in the lowest of the Ferruginous Sands, near Morton Farm, shows brown sand- stone dipping north-north-east at 35°, while the Nand-rock Series appears in a pit and road-cutting 400 yards west of Morton as a white sand with traces of blue clay. (2.) ArounpD THE SourHERN Downs. In describing the Athertield section we spoke of a bold escarp - ment or terrace formed by the ferruginous beds of Blackgang Chine (Group XIV. of Fitton), which runs through Pyle, Corve, and Kingston. There are many sections in the roads descending the hill at these places. On the top and extending nearly to the brow of the terrace, soft, brown, buff, and white sand appears similar to the sand at Cridimore (p. 42), and approaching the type of the Sand-rock Series. Lower in the hill-side, ereyish-green sand follows, weathering brown, and of considerable thickness, On descending to the foot of the escarpment, we find a line of springs and a belt of peaty ground marking the outcrop of a soft and clayey bed, doubtless the * foliated sand and clay ” of Walpen Chine (Group XII. of Fitton). The escarpment spoken of runs through Kingston, and, sweeping thence to the south-west round Gun Hill, points for Haslett and Wolverton, but becomes obscure in that neighbourhood. A second terrace is formed locally by a thick bed of red and brown sand with numerous grains of iron-oxide. This feature includes the bold brow known as Warren Hill, three quarters of a mile west of Corve, and stretches thence by Dungewood towards Small Moor. There, Jike the other terrace, it also becomes obscure, so that whether it is a continuation of the bed which we traced by Brook Church most be left in doubt, LOWER GREENSAND. i) It will be noticed that the source of the Medina at Chale Green is situated on the upper of these two terraces. The valley of the river gains in depth northwards, while the strata, except for some very gentle undulations, remain horizontal. It is probable that the depth thus cained is sufticient to let the stream reach the “ foliated sand and clay,” and that this may account for the width of the alluvial flat; but there is no gure! to prove it. The hills are capped by buff and white sand , while their sides are formed of brown and erey sands with an occasional seam of iron-oxide. The Sand-rock Series is exposed at Chale Farm, Gotten, and at the north end of St. Catherine’s Down, with its usual character of fine soft white sand. But its outcrop, though broad, is partly overspread by Gault, which, owing to the influence of percolating water, has flowed down over the intervening Carstone. We now enter the drainage area of the (East) Yar. Blake Down, here forming the watershed between this river and the Medina, is a Jong spur of the uppermost beds of the Ferrucinous Sands, capped with flint-gravel. As the river is about 100 feet below the highest strata of this spur, the “foliated sand and clay” might be expected to be reached. There can be little doubt that this is the case, for 1 terrace, closely resembling that of Pyle, Corve, and Kingston, runs through Godshill, aprile of Sandford, towards Lealans, and perhaps to Banstead, From the foot of the bold brow which terminates this terrace at Gods- hill springs wander through wide peaty marshes, as at Corve, while the brow itself is “composed of a ferruginous sand and greyish green sand, exposed to considerable depth in the road- cuttines. | ; The lower beds of the Sand-rock Series are scen in a pit near Sibbecks, which gives the following section :— Freer. Soft sand with seams of clay - - 20 Soft yellow and white sand-rock (perhaps the third sand-reck of Fitton) - 18 Thin-lbedded yellow an white sand with brown loamy partings - - 6+ Similar beds are seen in the grounds of Wydcombe, Redhill, Fairfields, and under the gravel at Ford Farm. Near Itchall a pit exposes the top of ‘We series, namely, white sandstone, more than fifteen feet thick, overlain by eight feet of Carstone. The base of the series is difficult to fix throughout the neighbour- hood of Chale Green, but a blue clay seen in the teak south of Roud, in the lane at Russell’s Farm, and in the high-road north-east of this farm, is presumably the same bed avicch we have already noticed at the top of the Ferruginous Sands at Shanklin. The characteristic scenery produced hy the Sand-reck Series and the overlying Carstone is admirably shown around Sainham and Godshill Park. The base line of the Carstone, the beds being nearly horizontal, meanders round a number of short but deep 46 GEOLOGY OF THE ISLE OF WIGIIT. valleys, the sides of which are composed of bright-white sand and sand-rock, A remarkably coarse grit has been already described as occur- ring at the base of this series near Blackwater; a somewhat similar bed may be noticed in a lane south of Sandford, but not elsewhere. The clay-bed of Roud, however, referred to above, seems to have been well developed at Sandford, where it was formerly worked for bricks, and where it is still exposed to a depth of S feet. An outlier of the Sand-rock Series occurs here, its top capped with gravel, its sides showing the usual white sand soil, while a line of springs around its base marks the position of the clay-bed. Crossing the Wroxall stream, we find a sand-pit near Winstone, showing 10 feet of white sand, and another by the side of the railway half a mile east of Winstone, presenting more than 18 feet of white sand with thin lines of clay. The neighbouring railway cutting is much overgrown, but reveals some white sand in the upper part. The base of the series is marked near Rill by a fall in the ground and the issue of springs. In Apsecastle Wood and the adjoining valleys, the features of the Sand-rock Series are finely shown, a remarkably good section having been opened out in the railway cuttings. We may con- veniently take up the description at the east end of the cuttings, where we left it in speaking of Shanklin. It will be remembered that two clay-beds occur in Knock Cliff. The upper «appears to be the one worked in a brick-pit west of Gatten, where, how- ever, it seems to be impersistent. The lower bed is worked by the side of the railway at Lower Hide, where it is a stiff dark-blue clay. The sand hetween the two beds is dug in a pit on the opposite of the line, which exposes :— Freer. Brown irony sand - - - - 4to6 Coarse grit or fine gravel - - - lto3 White sand - - - - - 144 The railway cutting commencing 500 yards east of Lower Hide gives a more complete section of these sands and of the upper clay, which has here again developed itself. A descending section runs as follows :— Railway Cutting three-quarters of « mile west of Shanklin, Fret, Dark clayey sand - : - - - 4 Dark-green sandy clay with scattered grit and pyritised wood - - - - 15 Brown pebbly and ferruginous grit with wood, about - cs White sand with black grains - - Z 2 2 Hard brown pebbly rock - . yo oD Coarse brown grit with numerous concretions - - 5 Grey sand or white sand with black grains —- - 5 White sand-rock with bright-yellow and brown staining 14 Dark sands - - : - x a Bue 503 —— LOWER GREENSAND. 47 The strata dip gently (at about 2° to 3°) a little to the south of west, and the green clay slopes down to the level of the rails in the next cutting. The sands lying upon this clay are dark and ferruginous, but are not well seen. The upper clay-bed, seen near Upper Hide, runs along the valley in Apsecastle Wood, where it has caused a good deal of slipping ; the lower clay-bed occurs at Apse Farm, but elsewhere is overspread by a downwash of sand. The Ferruginous Sands between these localities and the River Yar form an undulating tract, in part overspread with river-gravel, but in part rising into flat-topped hills, capped with gravel. The dip, if any exists, is too gentle to be detected in the small sections that vecur, except on Blackpan Common. The features of this tract suggest that the same beds which form the escarpments of Pyle and Kingston, and of Godshill, extend here across the valley of the Yar in a neck of about a mile in breadth. The base line of the beds on the east side of the neck seems to run from the cliff near Little Stairs Point, by the west of Lake, past Borthwood, across the river near Alverstone, and thence eastwards. The western boundary which we have already traced through Godshill to near Branston, seems to be continued in the hill on which Newchurch stands, and to trend thence eastwards, but all evidence of its position is lost in the valley. INDICATIONS OF CONDITIONS UNDER WHICH THE Lownr GREENSAND WAS DEVOSITED.* “ At the close of the deposition of the Wealden, there appears to have been a sudden depression of the bed of the great fresh- water estuary, and an influx of the sea. The first effect of such an influx would be the destruction of the animals in the estuary not adapted for living in salt water; hence we find a total de- struction of the Wealden animals, the remains of which accumu- late towards the point of the junction of that formation with the Lower Greensand,—a fact which indicates the nature of the change. Even the Cerithium [Vicarya], although belonging to a genus many species of which are capable of living in the depths of the sea, was destroyed, notwithstanding that its appearance, only in the uppermost beds of the Wealden, indicates that its presence there was due to the commencement of the very state of things which eventually destroyed it. That the depression was of some extent, though not, perhaps, of very many fathoms, is indicated by the nature of the animals which lived in the first-formed sea- bed, and which, when they died, were often embedded in the fine and probably fast-depositing mud, in the vertical position which it * On the Section between Blackgang Chine and Atherfield Point, by Capt. L. L. B. Ibbetson and Prof. Edw. Forbes. @roc. Geol. Soc., vol. iv. p. 409 (1844). 45 GEOLOGY OF THE WLE OF WIGHT. is the habit of animals of such genera as Pinna and Panopea to assume when alive.* “ After this a temporary change followed, when an influx of sand, mingling with the calcareous mud, caused a state of sea- bottom peculiarly favourable to the presence of animal life. In this way were called into existence a multitude of species which were added to those which had appeared before thera. ‘This was, in fact, such a state of sea-bottom as is now presented by great shell-banks; but it does not seem to have lasted long, and new depositions of mud appear to have extinguished some forms, whilst others suffered by the change only in the diminution of their numbers. In the midst of this muddy epoch, a temporary and peculiar condition of sea-bottom, forming what are now called the Crackers, called forth the presence of numerous mollusea, at first of various species of the genus Gervillia, and afterwards of Auricula [Avellana], Cerithium, Dentalium, and other univalves, which appear to have enjoyed but a brief existence (as species) in this locality, since similar conditions were never afterwards repeated. The greater number of the Gasteropodous mollusca of the English Lower Greensand are found within this very limited range. At the close of the deposition of this great mass of clay there was for a time a great multiplication of the individuals of certain Brachio- poda, which had commenced their existence in the lowest beds. Thus Terebratula Gibbsii [Rhynchonella gibbsiana| suddenly appears in immense abundance, covering the bottom of the sea, and predominating over the animals among which it had previously been but thinly scattered. “ This lowest zone of Terebratu/e marks the commencement of a new state of sea-bottom where sands predominated over the clays, each interval of deposition being usually marked by the presence of a layer of Gryph@a [Exogyra] sinuata, the period of rest being almost always sufficient to enable the Grypheu to attain its full growth. Other bivalves are found with it, but in comparatively small numbers, and not such as are of gregarious habits. During the whole of this period enormous Cephalopoda, including species of Crivcerus aud Scaphites [-dneyloceras], fre~ quented these seas, and when dead formed the nuclei round which calearcous and sandy matter collected avd formed nodules. The death of these animals seems to have been connected with the periodical charging of the sea with sediment ; hence we find them usually alternating with the zones of Gryphea, and forming irregular bands in the intervening sedimentary depoxits. fi * « The sawe decided change from dark-coloured fresh water marls containin Melunopsis (or Metania) [Vieurya] and Cypris to marine beds, oecurs round he edge of the Weald, and was very well exposed at Haslemere during the cutting of the London and Portsmouth Railway,a few years back. In company with Piero Ramsay and Mr. ¥. Drew, I examined the passage beds, and found in the brown clay abundant tracks of marine worms, and the Panopea, vertical in their old burrows, withiu au inch or two of the dark marls. A ereut Perna, a coral (Holo- cystis elegans), and uumerous other fossils, occur in plenty just above hess “ J.W.Sasrer. Sve Geology of the Weald, p. 114 (Alem. Geol, Survey). LOWER GREENSAND. 49 “{n the midst of this epoch of Gryphea there is a sudden reappearance of the muddy deposits, during the predominance of which those animals adapted for suth a sea-bottom, and which had survived the deposition of the fullers’ earth, again multiplied, but the species which had become extinguished were not replaced by representative forms. This, however, did not last long, the sand again predominating with its zones of Gryphea and lines of Crioceras nodules. “A temporary multiplication of Terebratula sella suddenly marks a change in the zoological conditions,—for the Cephalopoda disappear, although the zones of Gryphea, which animal does not appear to have been affected by the change, (probably a change in the depth of the sea,) go on as before, there being, however, no alternating lines of nodules. It would seem that the sea began to shallow, probably from elevation of the sea-bottom, until at last the Gryphea itself disappears, the bands exhibit traces of the influence of currents, and become more gravelly ; lignites, indica- ting a shallow sea, become common, form belts in the ferruginous sand, and in one place a bed in the wavy blue sand, at a time when much iron was deposited. The deposition of the peroxide of sron appears to have been connected with the disappearance of the majority of mollusca, though Trigoniu, Thetis, and Venus occa- sionally occur in considerable numbers. In the uppermost strata scarcely any animal remains are found, and everything appears to indicate a barren and shallow sea, previous to a new state of things, when a fresh series of clays (forming the Guult) being deposited, the majority of the animal forms which characterise the clays of the Lower Greensand disappear, and are replaced by distinct species, representative in time.” CORRELATION WITH THE MAINLAND AND THE CONTINENT. Dr. Fitton first pointed out the identity of the fossils in the Atherfield Clay of the Isle of Wight with those of a clay in Sussex and Kent,* which corresponded to the Atherfield Clay, except in the absence of the fossiliferous stone known in the Isle of Wight as the Perna Bed. The calcareous nodules of the * Crackers Rock” were considered by him to represent the thick limestone (Kentish Rag) of Hythe, Maidstone, &c. The Carstone and Sand-rock Beds of the present Memoir were identi- fied by him as the upper division of the Lower Greensand which he had described at Folkestone, that is to say, the Folkestone Beds of the Geological Survey; while the great mass of beds intervening between the Sand-rock Series and the Crackers group were correlated with his middle division at Folkestone, now known as the Sandgate Beds. Lastly, he noticed that the Ferruginous Beds of Blackgang Chine (Group XIV.) and the corresponding bed of Horseledge, near Shanklin, contain the same species as are found in the Sandgate Beds at Parham Park » Proc. Geol. Soc., vol. iv. pp. 198, 208, and 396 (1848). E 56786. D 50 GEOLOGY OF THE ISLE OF WIGHT. and other places in Sussex, and near Sandgate,* thus obtaining further evidence of the correctness of the correlations given above. According to Mr. Meyer +t ‘the coprolite bed at Redchiff (de- scribed on p. 87) corresponds to a pebble-bed at Godalming which he considered to represent “a break in the hitherto continuous deposition of the Greensand,” and which he traced by Dorking, Nutfield, and Maidstone towards Folkestone. This bed he took as the base of his Folkestone Beds or upper division of the Lower Greensand. It cannot, however, be followed through the Isle of Wight, nor, when present, is it accompanied by any appearance of a break. But while this line fails us, we find that the base of the Folke- stone Beds, as drawn by the Geological Survey,{ corresponds well with the line at the base of the Sand-rock Series, which was inde- pendently selected as a boundary capable of being traced through the Isle of Wight. During the present year a brief visit was paid to that part of the Lower Greensand outcrop in the Weald, which lies nearest the Isle of Wight, for the purpose of comparing the strata in the two areas, the result being to confirm in every par- ticular the conclusions arrived at by Fitton. Lithologically, the brightly coloured clean quartz-sands of the Folkestone Beds at Pulborough, Midhurst, and Petersfield closely resemble the Sand- rock Beds of the Isle of Wight. In beth Sussex and the Isle of Wight, moreover, these sands pass down into a group in which beds of shale are conspicuous, and which is more evenly bedded and more mixed with loam than the Folkestone Beds.§ At Pulborough a band of shale, 30 feet thick, and taken by Mr. Gould as forming the top of the Sandgate Beds, corre- sponds closely in character and position to the thick clay-band of Blackgang Chine, and of the railway cutting near Shanklin, described on p. 46. The identification on the mainland, however, of the rock now mapped in the Isle of Wight under the name of Carstone is attended with some difficulty. The description of this rock and its probable relations will form the subject of the succeeding chapter. The great devclopment of beds of corresponding age on the Continent has been pointed out by Professor Judd, of whose conclusions the following is an abstract. The Rhodunien of Switzerland, which forms a complete link between Upper Neoco- mian (Apticn) and Middle Neocomian (Uryonien), has been shewn by M. Renevicr** to be the equivalent of the Perna Bed, Athevfield Clay, and Crackers of the Atherfield section. Among the fossils * Quart. Jour, Geol. Soc. vol. iti, p. 811. 1847. Sce also Geolovy of the Weald (Geological Survey Memoir), pp. 136, 137. : { On the Lower Greensand of Godalming (Proc. (#.ol. Assoc.), 1869, p. 10. f Geology of the Weald (Geological Survey Memoir), 1875, pp. 138-144, § The difference is greater than appears at the first view of sand-pits in the two subdivisions. The Folkestone Beds are used commercially for building sand, the Sandgate Beds for mouldiny purposes. || Geology of the Weald, p. 136. © Quart. Journ. Geol. Soc., vol. xxvii. pp. 223-5. 1871. ** Bull, de la Soc. Gcol. de France, 2me scr, tome xii. p. 89. . LOWER GREENSAND, 51 Ammonites Deshaysii, which occurs in the “marine band” at Punfield [the top of the Atherficld Clay] abounds in the higher beds of the Neocomian, but is not known in the Urgonien or any lower bed. Vicarya Lujani and several other of the Punfield shells are well-known and characteristic Rhodanicn forms. In the east of Spain* the upper and middle Neocomian rocks are greatly developed, and contain beds of coal and jet which are extensively worked. They are divisible into three series, namely :-— An upper series of variegated clays and brightly coloured sands (crimson, grey, violet, and white), 600 feet in thickness, probably in great part freshwater, but containing a few marine shells of Upper Neocomian affinities. A middle series, consisting of ferruginous sandstones and lime- stone, alternating with sandy clays, and containing ten beds of coal, lignite, or jet at Utrillas, where they are 530 feet thick. These beds contain the same fossils as the “ marine band” of Punfield. They are characterised by six species of the gasteropod Vicarya, three of which occur at Punfield, and one in the Rhodanien of Switzerland. Hardly a fossil is found in the “ marine band” of Punfield [the top of the Atherfield Clay] which does not also occur in these Spanish beds. A third and lowest series, consisting of about 500 feet of alternations of limestones, sandstones, and marls, with jet and coal, and containing Urgonien fossils. * See also H. Coguand. Description géologique de la formation crétacée de la 9 Province de Teruel. Bull. Soc. Géol. de France, sr. 2, tome xxiv. p. 144 (1868). 52 GEOLOGY OF THE ISLE OF WIGHT. CHAPTER V. LOWER GREENSAND—continued. THE CARSTONE. INTRODUCTION. Tris name has been given to a coarse and highly ferruginous grit, which may be traced continuously at the base of the Gault through the Isle of Wight. Wherever fully exposed the Carstone is seen to pass up into the Gault; on the other hand a fairly sharp line at its base separates it from the Sand-rock Beds, with an appearance even of slight erosion at times, though we have no evidence of an actual unconformity. The feature produced by this comparatively hard grit, capping the soft sands of the Sand- rock Beds, is especially prominent where the beds are nearly horizontal. It is most marked at Marvel Wood, near Shide, and in the neighbourhood of Godshill. The Carstone varies considerably in thickness within the Island. From 6 feet at Compton Bay it expands to 12 feet near Blackgang, to 30 feet near Bonchurch, and to no less than 72 feet at Red Clif. At Punfield, on the other hand, it seems to be represented by a few inches only of pebbly grit, but is not seen there in place. The Carstone, therefore, thickens towards the north-east, while the other subdivisions of the Lower Greensand increase towards the south. The Carstone corresponds to the upper part of Fitton’s Group XVI. The present name* has been adopted on account of the resemblance the rock bears to the Carstone of Lincolnshire and Norfolk, of which there is reason to suppose it to be the stratigraphical equivalent. For the Carstone of those Counties passes up into the Red Chalk, which there occupies the position of, and partly represents the Gault. Moreover, further south we find that the Gault when it makes its appearance passes down into a grey clay with phosphatic nodules, which in its turn shades into a lower light brown sand with phosphatic coneretions and numerous fossils. f These fossils, as pointed out by Mr. Teall, are found in the south of England to occur in the Gault, and in the dmmonites mammillurts zone, which lies next below the Gault. Ie infers, therefore, that “ the Norfolk Neocomians [Carstone] are found to resemble both stratigraphically and paleontologically the Folke- stone Beds of the South” (op. cit, p. 22). But we have already pointed out that the Folkestone Beds asa whole are comparable to the Sand-rock Series. It remains to be seen whether any sub- * The name is applied locally in the Weald to the portions of the Folkestoue Beds, which have been cemented hy brown iron oxide into a hard rock, t The Potton and Wicken Phosphatic Deposits (Sedgwick Prize E f by Mr. J. J. H. Teall. Cambridge, 8vo., 1875, p. 20. ? tn LOWER GREENSAND. 53 division of the Folkestone Beds corresponding to the Carstone of the Isle of Wight can be recognised on the Mainland. The Carstone thickens in the Isle of Wight towards the north-east, yet in the part of the Weald which is nearest to the Island, the Folkestone Beds preserve their character of fine-grained quartz sand up to within a foot or two of the base of the Gault. But on the other hand the base of the Gault invariably consists of a more or less pebbly grit, or of a sand with phosphatic nodules. At Steep Common, near Petersfield, the Gault is green and sandy towards the base, contains phosphatic nodules, and rests on a “brown and green sand, with large pebbles, and at one place phosphatic nodules at base.”* Further east, near Midhurst and Pulborough, the base is formed by a pebbly grit, varying from 8 to 10 inches only in thickness, but conspicuous from its extreme hardness and from its deep-brown or blood-red colour. The pebbles in this band range up to half an inch in length, and their presence, together with the gritty character of the rock, dis- tinguish it, even apart from its hard ferruginous cement, from the fine-grained sand of the Folkestone Beds. Elsewhere in the Weald the base of the Gault is marked by nodules of phosphate of lime or of iron pyrites, the hard pebbly grit described above being confined to the neighbourhood of Midhurst and Pulborough. Associated with the nodules, and likewise in a phosphatic state, there are fossils of Gault affinities, viz., Ammonites Beudanti’, A, mammillaris, Exogyra conica, Inoceramus Salamoni, Naticu gaultinc, and others, which have led to the remark that the Folkestone Beds are more closely connected with the Gault than with the underlying Sandgate Beds. In 1859 Professor A. Gaudry remarked that the sands at the top of the Lower Greensand at Folkestone and Wissant in the Bas-Boulonnais contain lmmonites mammilliris, and proposed to group these sands with the Gault on that account.t In 1868 Mr. Topley noticed that at Folkestone the Folkestone Beds both pass lithologically up into the Gault, and also contain in their upper part “nodules with Gault-like fossils,” { and the same view of their relationship was taken by M. Barrois, who mentions that not only are several fossils of the Ammonites mammillaris zone, which in France is included in the Gault, found in the upper part of the Folkestone Beds, but that the brachiopods which occur in this zone are especially abundant in the lower part of the same strata. He concludes that unless the Folkestone Beds, like the A. mammillaris zone, are classed with the Gault, there is no satisfactory upper limit to the Aptian in England.§ Mr. Price, on the other hand, would retain the zone of A. mammillaris in the Upper Neocomian.| * Geology of the Weald, p. 142. 2 + Bull. Soc. Géol. de France, séx. 2, vol. xvii. p. 32. 1860. On the Lower Cretaceous Rocks of the Bas-Boulonnais, &c. Quart. Journ. Geol. Soc., vol. xxiv. p. 474. 1868. i Mf $ L’Age des “ Folkestone Beds” du Lower Greensand. Anna, Soc. Géologique du Nord, t. iii. p. 23. 1875. || Monograph of the Gault, 1880, p. 35. 54 GEOLOGY OF THE ISLE OF WIGHT. The nodules and fossils referred to above occur in three to four feet of sand, which form the top only of the Folkestone Beds. This sand, which both passes up into, and possesses this palaonte- logical affinity with the Gault, seems to be an expanded repre- sentative of the grit-band of Midhurst and Pulborough, which also passes up into the Gault. The grit-band, as before explained, is sharply marked off from the underlying mass of the Folkestone Beds; if the sand with Gault fossils could also be separated from the Folkestone Beds, we should no longer have to face the anomaly of the upper member of the Neocomian group being characterised bya Gault fauna, and should also be able to point in the Wealden area to a basement-bed to the Gault corresponding to the Carstone of the Isle of Wight. At present, however, it must remain uncertain whether an upper portion of the Folkestone Beds ean be separated off, as an equivalent to the Carstone of the Isle of Wight, or whether the Carstone changes horizontally into a sand of the usual Folkestone Beds type during its passage north- eastwards below the Hampshire Basin. The fossils of the Carstone of the Isle of Wight, so far as they go, indicate as cloxe a relationship with the Upper Neocomian as with the Gault. Two forms, however, occur which are not known lLelow the Folkestone Beds, viz., Lima parallela, Sow., which ranges through the Gault, and Ammonites Beudantii, Brong., which occurs in the 4. mammillar’s zone both in England and France, as well as in the zone between the Upper and Lower oe to which it gives its name. The following is the complete ist -— Fossils of the Carstone, Wood (Bonchurch and Dunnose). Echinoderm, fragment (Bonchurch). Enallaster (Hemipneustes) Fittoni, Forbes; as a pebble (Bonchurch). Crustacean fragment (Bonchurch). Hoploparia longimana, Sow. (Sandown and Dunnose), Avicula (Bonchurch and Blackgang). Astarte (Sandown). Cardium (Bonchurch and Sandown). Exogyra (Sandown and Blackgang). Leda scapha?, D’Orb. (Sandowni. Lima (Blackgang). Lima parallela, Sow. (Blackgang). Nucula (Blackgang). Panopea ?P (Fitton, Blackgang). Pecten orbicularis, Sow. (Bonchurch, Dunnose, Sandown, Blackgang). Pecten quinquecostatus, Sow. (Sandown). Plicatula carteroniana, D’Orb. (Sandown). Tellina (Sandown). Venus ? (Fitton, Blackgang). Actzeon (Sandown), Pleurotomaria (Blackgang). Solarium (Forbes, Blackgang). Trochus (Bonchurch). Ammonites, fragment (Blackgang). we Beudantii, Brong. (Blackgang). Lamna, tooth of (Dunnose). LOWER GREENSAND. 55 Comrton Bay To Repcrire. At Compton Bay the Carsione is a brown sandstone, having as its basement layer a band, three inches thick, of quartzite pebbles, ranging up to three-quarters of an inch in leneth, with rolled phosphatic pebbles, many bits of wood, and cylindrical concretions which seem to have been formed in place. Though the beds below also contain pebbly bands, they appear to be more of the type of the Sand-rock Series, and to be divided from the Carstone by a hard and fast line. Upwards the Carstone passes gradually into the Gault, the nature of the junction being shown in Fig. 7 (p. 23) and in the accompanying sketch by Professor E. Forbes. Fia. 13. Junction of the Gault and Lower Greensand in Compton Bay. Fr, In. a. Dark blue sandy clay (Gault). ; b. Brown sand with a pebble-band, three inches thick, at the base, containing quartz-pebbles, many pieces of wood, and some phosphatic pebbles (Carstone) - 60 c. Blue sandy clay - - 2 6 d, Grey and greenish sand with small quartzite pebbles at the top and the bottom, and with a layer of pyritised wood, 4 feet from the base = 5 - 13 e. Bright-yellow sand - - - - 9 f. Aferruginous band, about es - : : = g. Irregularly interlaminated white sand and blue clay (for the continuation of this section, see p. 22). ooo Eastwards from Compton Bay there is no section of the Car- stone, though its position can be determined with some accuracy by the nature of the soil. In the section of the Sand-rock Series at Rock (p. 41) the base of the Carstone is exposed, but no re. ; There are indications, however, of the steady thickening of this subdivision eastwards. Not only does the outcrop widen, but south of Coombe Tower the rock begins to form a distinct escarp- ment, which gradually becomes the best marked feature in the Lower Greensand. Wherever exposed the rock consists of a brown and ferruginous grit. 56 GEOLOGY OF THE 18SLE OF WIGILT. By the side of the high road from Chale to Chillerton a pit shows the base of the Carstone, consisting there of a ferruginous grit with a few pebbles at the baze, and resting on sand and cliy with markings resembling fucoids, about 6 feet thick, under which fies white sand. The escarpment continues to grow in importance, but excepting in a lane near Roslin, presents no sections till we reach Rookley Green, the road-cutting south of which place shows yellow and white laminated sand and loam (Sand-rock Series) in the lower part, and ferruginous sand and loam with some clay nearer to Rookley Green. Thence the Carstone sweeps round to the east and north of Rookley, and crosses the same road south of Blackwater, in a cutting where it rests on white sand. It is next seen in small pits near Park Cottage, but is better exposed in a road-cutting at Sandway, 300 yards east of White- croft, where it rests on the white sand previously alluded to (p. 42). A short distance to the north, at Marvel Wood, the Carstone rises into one of the boldest escarpments in the Isle of Wicht, of which the section was given on p. 42. It here rests on sands in which current-bedding is very conspicuous. The definitencss of its base, taken together with the manner in which it crosses the edges of the current-bedding planes of the strata below, gives a strong appearance of unconformity, which is heightened by the fact that the grey sand, 3 feet thick, on which the Carstone reposes, looks as if it had been “reconstructed” from the clays and white sands of the Sand-rock Series. ‘The mapping of the Island as a whole did not, however, support the idea of an un- conformity at this horizon, though there may have been local erosion and redeposition. The lase of this subdivision may be followed along Marvel Woo to the head of the valley on the west side, where two small pits give a similar section. The Carstone is next seen in the lanes near Newclose House, but, owing to the rapidly increasing dip, the outcrop becomes narrow, and the escarpment insignificant. On the east side of the Medina it is seen in the Jane leading up the hill past Standen. The upper beds of the Sand-rock Series are also brown here, but may be distineuished without difficulty from the coarse ferruginous grit of the Carstone. B = From St. George’s Down eastwards the position of the Carstone is marked by a slight rise in the ground,and the highly ferruginous soil. The rock is exposed in the road-side at Great East Standen, but does not appear again till we reach a small opening 300 yards south-east of Heasley Lodge, where it rests on buff sand. At Knighton it forms a fairly well-marked feature, and is exposed in the wooded bank on the east side of the stream, and again in the valley a quarter of a mile west of Kern, East of Kern the dip increases and the outcrop narrows down to a mere line. There is a small exposure 250 yards north-west of the Roman Villa at Brading. LOWER GREENSAND. 57 This brings us to the coast section at Redcliff, the section of which was given on p, 35. The Carstone here, as everywhere, passes up into the Gault, and shows at this locality a greater thickness than in any other part of the Isle of Wight, namely, 72 feet 9 ches. A small fault, previously alluded to, is clearly shown in the Carstone, and in some of the beds below it. Such phosphatic concretions as occur consist of cemented masses of grit, and seem to have been formed in place. The whole rock is markedly ferruginous. From Niron anp BLackGANG TO SHANKLIN AND Boncnurcy. We will now trace the course of the Carstone around the southern hills of the Island, proceeding as before from west to east. The exposures about the Undercliff near Blackgang are numerous and easily accessible. The Carstone forms the brow of a shelf in the cliff, which is occupied by the Gault, or more usually by the débris of Upper Greensand and Chalk that has slid down over the Gault. This brow may be traced continuously from Chale to the Chalybeate Spring. It reappears above Knowles, and near the foot of the cliff below Niton presents its most eastern exposure. Still further east the southerly dip is believed to carry the Carstone down to the level of the beach, but no rock appears zz situ to determine the point. The following section was noted above the Chalybcate Spring :— Fr. In. Gault; blue clay passing down. Brown grit, interbedded with grey clay, and containing phosphatic nodules in the upper part = - - & O Capes Blue clay - - - - - 38 0 arstone\ Reddish-brown grit, very red in parts - 10 Line of small quartz pebbles with rolled phosphatic nodules up to 2 inches in diameter - - - - - 0 2 Sand-rock Series (for details, see p. 31). 12: 2 In the cliff below Niton we find the following details :-— Fr, In. Gault; blue clay passing down. Brown grit = si - < i. “B08 Clay-parting - - ~= - - Ol Carstone< Brown grit with phosphatic noaules - - 14 | Brown sand and clay je 7 ‘ : J | Pebbly and ferruginous band - Sand-rock Series; grey sand with scams of blue clay, seen to 44 ft. 58 SEOLOGY OF THE ISLE OF WIGIT. In Blackgang Chine, and on either side of it, the Carstone with the base of the overlying Gault is repeatedly exposed, but a little north of the Chine, reaching the top of the cliff, it strikes inland, its base being exposed in the bill on the south sile of the high road near Cliff Terrace. On proceeding inland along the outcrop of the Carstone, we are soon «truck with the fact that it is more often than not ovér- spread with Gault clay. The appearance of the ground at once supplies the explanation. Over large areas the clay from the Gault outcrop has slid down and spread itself as a skin over a more or less even slope of Carstone, but is still easily distinguished by the hummocky appearance of the vround it occupies, as well as by the character of the soil. In some places the clay has flowed down in the form of mud-rivers, keeping usually to the lines of hollow in its descent, but overspreading also many of the higher parts of the Carstone feature. ‘The course and limits of these mud-rivers or gutters may be distinguished, for many years after they have ceased to move, by the large sods of turf which have been torn off and heaped in a little irregular bank along their edges, and by the lines which still serve to indicate where the mass of moving clay was traversed by Jong curving cracks, convex in the direction of movement. The mud-rivers extend sometimes to a distance of a quarter of a mile or more beyond the base of the Gault. The sections along the western slope of St. Catherine’s Down are few and poor, but at its extreme north end pebbly Carstone rests on buff and white sand. On its east side the guttering of the Gault, assisted by the slight easterly dip of the strata, has been more than usually extensive, but the Carstone near Wyd- combe forms a characteristic feature. It may be followed round the south side of the house, and is secn at a small waterfall 350 yards south-east of it. Near here three outliers of Carstone cap conspicuous hills, the lower portions of which consist of white sand and sand-rock. The base of the Carstone appears in two sand-pits 300 yards west, and the same distance north of Itchall, which show clayey sand and ironstone resting on white sandstone. A ‘similar section occurs at Sheepwash, where the Carstone forms a fine escarpment, corresponding to the feature at Marvel Wood, which we have already described. The strata being nearly horizontal, the Carstone runs for a long distance along the tops of steep spurs of white sand and sand-rock that jut out from the hill-side. Presenting everywhere the same ferru- ginous character, it may be readily distinguished from the series below. The slippmg down of the Gault is especially noticeable south of Godshill Park. Redhill, where there is a good section of the Carstone, has been named, like Redhill in Surrey, from the ferruginous colour of the goil. In Appuldurcombe Park and about Wroxall, a large area is occupied by slipped Gault ; but the Carstone appears by the side of the road north of the village, and its base is well exposed at Yard Farm, where it rests on white sand LOWER GREENSAND. 59 At Winstone, a fine example of a mud-slide is crossed by the railway cutting, now grassed over. Another a little to the cast has travelled down a hollow in the hill-side, and is now being dug for bricks. On. the hill-side above the brick- -pit a small opening has been made in the Carstone, From here to Shanklin occasional small sections serve to fix the position of the Carstone, but call for no particular notice. In the great cliff-section, however, which extends from Knock Cliff to near Bonchurch, this subdivision is finely shown. It strikes the coast half'a mile north of Luecomb Chine, and forms thence the brow of the cliff to Monk’s Bay, where it comes nearly to the beach. West of this, through everywhere hidden by landslips, it probably descends to the level of the beach, as is believed to be the case near Niton. Everywhere it passes up into the Gault, and rests with a sharply-marked base on the brightly coloured sands of the Sand-rock Series. The following section was noted in Monk’s Bay :— Fr. TX. Gault. Blue micaceous clay passing down. ( Blue micaceous clay with lines of grit 3.0 | Brown ferruginous rock with derived phos- | phatic concretions pentatning oolitic grains of iron oxide ‘oad ji - Sandy and grit ue clay, passing down - Gorsions 4 Glave trowel a wath npdales asabove - Brown grit - : | Brown grit with many small ‘pebbles - | Pebbly band, with quantaites up to half-an- Linch in length - - O 3-6 Sand-rock Series. Bright-yellow and white sand, Sis: Har orocoo tw 34 6 A well-rolled specimen of Enallaster (Hemipneustes) Fittoni, Forbes, was found as a phosphatic nodule in the clayey brown grit, 3 feet thick. This fossil is recorded-as occurring at Horseledge (p- 261), and more abundantly in the same beds at Atherfield, and in the Hythe Beds at Hythe. Its occurrence therefore as a derived specimen in the Carstone is significant. 60 GEOLOGY OF THLE ISLE OF WIGHT. CHAPTER VI. THE GAULT AND UPPER GREENSAND. 1. Tur GAULT. INTRODUCTION. Tir Gault, which rests quite conformably on the Carstone, may be deserihed generally as a blue or bluish grey clay, more or less sandy, and with minute spangles of mica. It contains little or no calcareous wmatter, such proportion of this material as may have been originally present having been converted into sulphate of lime, which in the form of small crystals of selenite sometimes occurs in considerable quantity. The fossils are few, and dis- tributed at rare intervals. In thickness the Gault varices from 120 feet at Culver to 146 feet at Blackenang, and 139 feet in Compton Bay. At Punfield, where, however, it is difficult of measurement, it ix about 111 feet thick. In its upper part it becomes sandy and lighter im colour than in the lower beds, so as to pass almost insensibly into the Upper Greensand. The proportion of sand increases west- wards in these passage beds, so that at Punfield the name of Gault, as indicating a clay, becomes quite inapplicable. In the extreme west (Black Down) the whole formation scems to pass into a sand. LANDSLIPS. The Gault has received the name of the “blue slipper ”* in the Isle of Wight, from its tendency to give rise to landslips, or of «“ Platnore,” a name which was in former days applied to uny close black earthy stone or clay. The beautiful and romantic scenery of the Undercliff or “ Back ” of the Islind has been mainly caused by the sliding of the Chalk and Upper Grcensand over the unctuous surface of the Gault clay, the tendency to slide being principally due to a rather pronounced seaward southerly dip, and to the outburst of springs at the junction of the porous Upper Greensand and impervious Gault. * The term “slipper” is applied in the Island to any bed which gives rise to landslips. GAULT. 61 Through the greater part of the Undercliff the slippod materials assumed a position of rest before the commencement of the historic period. It seems likely that in the belt of ground occupied by the slip, the southerly dip was steeper than it is in the existing cliff, and that the strata now forming this cliff will never be in a position to slide so readily as those portions that have already gone, Still, as the sea, in the course of centuries, removes the fallen débris which forms the coast, the movements will doubtless be renewed from time to time. Indeed, at Blackgang and Bon- church, the west and east ends respectively of the Undercliff, there have been great slips within the present century. The following account of the East End Landslip, which took place in 1810 in Bonehureh and Luccomb, is taken from one of Mr. Webster’s letters, dated May 27th, 1811, and published in Sir Henry Englefield’s Isle of Wight (p. 131) :— “T was surprised at the scene of devastation, which seemed to have been occasioned by some convulsion of nature. A con- siderable portion of the cliff had fallen down, strewing the whole of the ground between it and the sea with its ruins; huge masses of solid rock started up amidst heaps of smaller fragments, whilst immense quantities of loose marl, mixed with stones, and even the soil above with the wheat still growing on it, filled up the spaces between, and formed hills of rubbish which are scarcely accessible.” “ Nothing had resisted the force of the falling rocks. Trees were levelled with the ground; and many lay half buried in the ruins. The streams were choked up, and pvols of water were formed in many places. Whatever road or path formerly existed through this place had been effuced; and with some dittculty 1 passed over this avalanche which extended many hundred yards.” “ Proceeding eastward, the whole of the soil seemed to have been moved, and was filled with chasms and bushes lying in every direction . . . . I perceived, however, on my left hand, the lofty wall of rock which belonged to the same stratum as the Underclitf” This description of the scene is equally applicable at the present day, except that the ruins are covered with vegetation. Huge pinnacles or slices of the Upper Greensand have moved down a few feet only and remain with their upper parts resting against the parent cliff, but separated from it below by a narrow cleft, along which it is possible to squeeze one’s way. The top of the Gault is everywhere concealed by fallen rock. At the west end of the Undercliff, under Gore Cliff, a great slip took place in 1799, and the movement has been renewe from time to time ever since. A letter, dated Niton, February 9th, 1799, and published in the Isle of Wight Magazine for the same year, is quoted by Mr. Norman as follows:*—“ ‘The whole of the ground from the cliff above was seen in motion . . . . The * Geological Guide to the Isle of Wight, 8vo., Ventnor, 1887, pp. 187-189. 62 GEOLOGY OF THE ISLE OF WIGHT. ground above, beginning with a great founder at the base of the cliff immediately under St. Catherine’s Down, kept gliding forward, and at last rushed on with violence, totally changing the surface of all the ground to the west of the brook that runs into the sea, so that now the whole is convulsed and scattered about, as if it had been done by an earthquake. . . . . The cascade which you used to view from the house at first disappeared, but has now broken out and tumbled down into the withey- bed, of which it has made a lake.” Mr. Norman relates that an enormous mass of rock by the road beneath Gore Cliff “once formed part of a large pinnacle which had become loosened from the cliff and overhung in a manner extremely threatening to the safety of the public. The authorities decided upon its removal by means of gunpowder. In its fall it carried with it tons of adjacent rock and débris, entirely blocking and destroying the roadway made round the landslip of 1799” (op. cit., p. 189). The roadway has again been threatened with destruction (1887) by the constant slipping of the Gault, some of the rain gullies having cut their way into the slope as far as the seaward fence of the highway. The most striking feature in the central parts of the Under- cliff is the succession of short escarpments produced by the fall of slices of the Upper Greensand cliff’ These portions range in size from mere blocks up to slices of half'a mile in length. They have broken off along the vertical joints by which the sandstone is traversed, and as their bases slid forward over the Gault, have slowly acquired a steep landward (northerly) dip. The process has been repeated several times, thus producing at different levels in the Undercliff a series of Upper Greensand escarpments, separated by deep hollows, which have been not uncommonly occupied by natural lakes. The distance to which they have descended varies indefinitely. Above Bonchurch a very long but narrow slice has moved a few feet only, and still forms the principal face of the cliff. But many others, with a portion of Chalk above them, have descended to the beach some 300 feet below, and from a quarter to half a mile distant. Such wholesale shpping is, generally speaking, confined to the coast, but some large masses of Greensand have slid down on all sides of St. Catherine’s Down, and from the shoulder which separates Shanklin and Luccomb. The slipping down of the Gault in great mud-rivers all round the southern Downs has already been noticed (p. 58). It does not take place alone the Central Downs of the Island, where the dip is generally at a steeper angle and into the hill-side, : Drscrierion or Srorrons, The best section of the Gault is afforded in Compton Bay, where nearly the whole deposit may be examined, the section being as follows :— 2 GAULT. 63 Section of the Gault in Compton Bay, Feerr; Upper Greensand (for details see p. 68). (Hard blue clayey bands with fucoidal | markings alternating with sandy bands, Passage } containing iron pyrites - - 6 Beds. | Pale blue silty sand or sandy micaceous clay with fucoidal markings, weathering Gault < L yellow - % - 30 | Clay, as above, but of a deeper blue - = - 8 Greenish clay - - - - - 2 Blue clay as above, with fish-scales, &c. in several bands - - a - - 20 Blue clay - - - - - 73 Carstone (for details see p. 55). 139 — The passage up from the Gault is illustrated in the accompany- ing sketch (Fig. 14), made in the cliffs at Compton during the progress of the geological survey of the Island in 1852. Fig. 14. Junction of the Upper Greensand and Gault in Compton Bay. Fa, SEN. a. Upper Greensand. Hard concretionary band, with phos- phatic nodules - ct de = ee ee a, b. Passage by a bluish sand with thin fucoidal markings, or into - - - - - - 6 e. Green sandy band with afew nodules - - 0 d, Dark blue sandy clay - - < = e. Paler and darker beds with small nodules: Fossixs, Gryphea, Vermicularia, Arca (rare). The passage beds, in the former Edition of this Memoir, were included with the Upper Greensand. Lithologically, however, they are more nearly allied to the Gault, with which they have usually been grouped of later years. Downwards the Gault passes into the Carstone as described on . 55. In its lower part Mr. Norman observed Lnoceriunus sulcatus, Nautica gaultina, and Ammonites dentatus (var. of A. interruptus, D’Orb.), the last-named occurring as a brittle coal- 6-4 GEOLOGY OF THE ISLE OF WIGHT. black material, the inner whorls permeated by a phosphatic substance.* At Blackgang the numerous sections in the lower part of the Gault have been noticed in the description of the Carstone. Tnoceramus sulcatus and I. concentricus have been found in a gulley west of the hotel. The top of the Gault appears in Gore Chiff, this being the only spot in the Undereliff where it is not concealed by fallen rubbish. The beds are similar to those at Compton Bay, and the thicknesses differ but little. According to Mr. Simmst there are here 43 fect of light-coloured Gault (passage beds), and 103 of blue Gault, giving a total of 146 feet. The sections in the chif from Bonchurch to Knock Cliff show the lower beds of the Gault only. The passage downwards into the Carstone may be conveniently examined in the brow of the cliff near Bonchurch (p. 59). In Sandown Bay the position of the Gault is marked by a narrow hollow in the cliffs. The passage beds into the Upper Greensand above and the Carstone below are there exposed, but the rest of the deposit is concealed by vegetation, The top layers consist of alternations of blue sandy clays and sands with Vermiculuria, about 15 feet thick, and the lower beds of darker blue micaceous clay. The total thickness of the Gault here is about 120 feet. Through the central parts of the Island, the Gault occupies a narrow belt of low ground, separating the Upper and Lower Greensands. When not overspread by a downwash of sand, the soil of this belt is wet and rush-covered, and presents a characteristically different appearance from that of the strata above and below. But as a rule the Gault is entirely masked, and sections are exceedingly rare. The passage beds into the Upper Greensand are seen in a lane 100 yards south-west of Rill, near Chillerton. At Gossard Hill, near Rookley, where a long shoulder of Gault, capped by an outlier of Upper Greensand, juts out across the Medina, a brick- pit has been opened; but only the weathered surface of the Gault is worked, a pale-blue or nearly white structureless clay. A better section is provided in-the brick-pit at Bierley, near Niton, where the lower beds of the Gault are exposed. The brick-pits by the side of the railway between Wroxall and Shanklin are worked in Gault that has slipped down the _hill-side below the true outcrop (p. 59). One of the most noticeable features in connection with the outcrop of the Gault, is the copious supply of water which it throws out nearly all round the southern Downs of the Island. The greater part of the strata over-lying this clay being of a permeable nature, the rainfall is absorbed by them, and is thrown out in a line of springs along the top of the first imper- meable bed it encounters. ‘The springs are of course most copious along the hill-sides where the Gault is at the lowest level, the * Geological Guide to the Isle of Wight, p. 70. Tt Quart. Journ, Geol, Soc., vol. icp. 76 (1845). UPPER GREENSAND. 65 underground water naturally moving down the dip-slope of the beds; but, the dip being very gentle, there are springs along nearly the whole Gault outcrop. The most copious occur at Wydcombe, Bierley (utilised for the Niton and Whitwell Water- works), Niton, Whitwell, south and south-east of Wroxall, and in Greatwood Copse near Shanklin. The natural spring which formerly issued at the last-mentioned locality was utilised for the Shanklin Water-works, the supply of water having been some- what increased by driving a heading into the hill along the junction of the Upper Greensand and Gault. Ventnor is sup- plied by a spring issuing from the same strata, and met with in driving the railway tunnel. Several springs take their rise in the same neighbourhood, and were formerly used to drive a mill in Ventnor Cove. Along the central chain of hills the springs are less frequent, owing to the steep inward dip of the strata. But a fine spring issues at Bottlehole Well near Brixton, and another, issuing, however, in the Upper Greensand, gives its name to the village of Shorwell. About Chillerton and Gatcombe, where the dip is very gentle, numerous springs rise along the sides, and particularly at the heads of, the valleys. At Knighton there are good springs, which, supplemented by a well, are utilised for the supply of Ryde. CoRRELATION WITH THE MAINLAND. The zones into which the Gault of Folkestone has been divided by Messrs. De Rance* and Pricet have not been recognised in the Isle of Wight, and it is the opinion of the latter that the Gault of the Island is of Upper Gault age (Monograph of the Gault, p- 27). This opinion was founded on the occurrence of Juoceramus sulcatus, Ammonites rostratus, Solarium ornatum, Belemnites ulti- mus, &e. Of these Ammonites rostratus, and Inoceramus sulcatus are confined to the Upper Gault, but Belemnites ultimus ranges throughout the deposit, while Solarium ornatum occurs in the Lower, as well as in the Upper Gault. On the other hand 4m- monites dentatus is a variety of Ammonites interruptus which gives its name to the lowest zone of the Gault at Folkestone, from which it would seem that the Lower Gault also is represented in the Isle of Wight. This might be likewise inferred from the absence of any break in or below the Gault of the Island. A complete list of the fossils will be found in Table III. of Appendix IL. Uprrr GREENSAND. INTRODUCTION. This rock forms one of the most conspicuous features in the Island, namely the cliff which overhangs the Undercliff from * Geol. Mag. for 1848, p. 163. Tt Quart. Journ. Geol. Soc., vol. xxx. p. 342, 1874, and a Monograph of the Gault, 8vo. London. 1880. E 56786. E 66 GEOLOGY OF THE ISLE OF WIGHT. Bonchurch to Blackgang, and which reappears inland in thé bold brows of St. Catherine’s Down, Head Down, Gat Cliff, and St. Martin’s Down (Cook’s Castle Crag). In the central range the same rock forms the bold ridge of Rams Down, which is scarcely less conspicuous than the Chalk Downs themselves. The existence of these striking features is due to the hard- ness of a bed composed of alternations of chert and sand, and underlain throughout the central parts of the Island by a band of freestone. The position of the base of the Chert Beds has been indicated on the map by a broken line in the central and southern parts of the Island, principally on account of their topographical importance. Above the Chert Beds a variable thickness of glauconitic sands passing up into the Chalk Marl is known as the Chloritic Marl. Below the Chert Beds there lie from 70 to 90 feet of sands, called “malm,” with bands or lenticular masses of chert and cherty limestone or “rag.” Other local names of less common occurrence are “hassock” for the sands, “whills” for sandstone, “ shotter-wick ” for chert, “ firestone” for a stone formerly em- ployed for lining hearths, and “rubstone” for a stone once used for whitening hearths or dvorsteps. The thicknesses of the Malm Rock and Chert Beds are given for different localities in the Isle of Wight, and for Punfield, in the following table, the thickness of Gault at the samme spots being appended to show that the Upper Greensand and Gault thicken and thin together, and not one at the expense of the other. Punfield. Compton Bay. Gore Cliff. Culver. Feet. Feet. Feet. Chert Beds 6 13> - 27 45 86 1213 - 80 Malm Rock wot a = 944 2 Gault, - - + lil 139 - - 146 - - 120 The Malm Rock paxses downwards into the strata which have been above referred to as “passage beds” into the Gault. A convenient base for this subdivision has been selected near Ventnor by Mr. Parkinson* in a band of chert nodules from which the carapace and rib-bones of a fresh-water tortoise (Plastremys lata, Owen) were obtained by Mr. Norman, and the remains of Hoploparia Sacbyi, M‘Coy, by Mr. Saxby.t In other parts of the Island the base has been drawn where the clayey bands begin to pre- dominate over sandy beds. The zone of Ammonites inflatus occurs, according to Mr. Parkinson, ratber more than 20 feet from the base, while -Lnmouites rostratus attains its greatest development about 11 feet from the top of the Malm Rock. By Dr. Barrois, however, the Malm * Quart. Journ, Geol. Soe., vol. xxxvii. p. 370 (1881), t+ Ann. May. Nat. Hist., vol. xiv. p. 116 (1854). UPPER GREENSAND. 67 Rock (excluding a few feet at the top) was grouped with the passage-beds into the Gault as the zone of Ammonites inflatus.* The most important bed commercially is the band of freestone, from 3 to 5 feet thick, above alluded to‘as occurring a short dis- tance below the base of the Chert Beds. This freestone is not recognisable in the east or west ends of the Island, but has been largely worked as a building-stone in the southern hills, being especially conspicuous in the cliff between Blackgang and Bon- church. Between it and the Chert Beds lie one or two bands of “firestone ” and “ rubstone.” The Chert Beds attain their fullest development near Ventnor. In Sandown Bay they can scarcely be recognised. The chert, though used for road-metal, is not much worked, except in gaining access to the freestone below. Some of the beds of chert are crowded with the spicules of sponges. Dr. Hindet remarked of the Chert Beds of the quarry at Ventnor Station that they “so abound with spicules that they may be considered as a continuous sponge-bed. . . . The chert is usually of a light brown tint, and in thin sections under the microscope it is seen to be filled with spicules and spicular casts imbedded in a translucent matrix of chalcedonic silica. The spicules are likewise of chalcedony, and their canals are infilled with glauconite. Another variety of chert, also very abundant, is of a grayish or greenish-white tint; it differs from the former in that the matrix is of amorphous silica, while the inclosed spicules are of chalcedony. The chert bands . . . . are enveloped in an outer crust, of varying thickness, of white or yellow siliceous porous rock, which is interspersed with the empty moulds of spicules. “In some of the thicker masses of chert there are cavities or pockets filled with spicules, loosely mingled in a grayish siliceo- calcarous powder, in which there are also numerous well-preserved foraminifera, chiefly of the genus Textulariv. The spicules in these cavities have undergone a remarkable alteration in structure ; they appear to have lost their original silica, which has been replaced by glauconite and some other silicate of a greenish-white aspect. The replacing material has only partially filled the form of the original spicules, and thus they look like mere shadowy casts of complete spicules. These in many cases are peculiarly distorted and contracted.” Spicules occurred in the lower beds in the quarry also, but not so abundantly. By Dr. Barrois the Chert Beds and the freestone below them were correlated with the Warminster Beds, A specimen of Clathraria Lyellii, a cycadeous plant, which it will be remem- bered occurs in the Wealden Beds, has been obtained from the Upper Greensand by Capt. Ibbetson in bastard freestone at the * Recherches sur le Terrain Crétacé Supérieur de Angleterre et de l’Irlande, p. 107. { Phil. Trans., vol. 176, p. 418. 1886. B 2 68 GEOLOGY OF THE ISLE OF WIGHT. base of the Chert Beds.* Another specimen has been recorded by Mr. Parkinson from the Chert Beds at Steephill, about 10 feet below the Chloritic Marl.t A femur of a reptile is stated by Mantell to have been found at Bonchurch three or four feet above the firestone.t For the other fossils the reader is referred to the tabulated lists at the end of the volume. Coast SECTIONS. 1. Compton Bay. The following details were observed in the cliff forming the west side of Compton Bay :— Chalk Marl (see p. 83). FEET. Chloritic Marl (see p. 81). ‘ Chert Green sand with 10 or 12 bands of Beas | chert, light-brown outside, blue | : inside - 13 ( Darker green sand, light-green when Tisex | | dry, with small scattered phosphatic Guecreawa nodules and lenticular masses of Malm Z chert or rag 32 Rock. \ Sandstone, jointed and weathering | into caves at the foot of the cliff. | Many black nodules scattered {. L throughout - - - 41 Gault - - Passage Beds (see p. 63). 86 The Chert Beds are not so well developed here as in the central parts of the Island, and the chert itself is more caicareous. The freestone bed also, so marked a feature in the Undercliff, cannot be recognised. 2. Blackgang to Shanklin. Gore Chiff shows the Upper Greensand in a form that is typical of the central and southern parts of the Island. The Chert Beds form a vertical face, deeply scarred by the weather, each band of chert forming a ledge, while the soft sands between have been scooped out by the wind. At the foot of this vertical part of the cliff the 5-foot bed of freestone runs for some miles and can generally be recognised at a glance. The Malm Rock below forms a steep, often precipitous slope. * Notes on the Geology and Chemical Coiistitution of the various i Isle of Wight, p. 25. See also Quart. Journ. Geol. Soc., vol. xxxvii. ae ne specimen is incorrectly stated by Mantell (Geol. Excursions in the Isle of Wight. pp. 215, 217) to have been found in the Chalk Marl. { Quart. Journ, Geol. Soc., vol. xxxvii. p. 372. 1881. t Geological Excursions, pp. 179, 180. UPPER GREENSAND., Gore Chiff. Chloritic Marl (see p. 81). Chert Beds. Alternations of chert and sand - Firestone and rag 5 = - Hisastous eae froestone: 1 ft. el Freestone Malm Rock< Sand with rag - - »» With many ledges of rag - - Blue clayey sand - - (Blue micaceous sandstone - - Gault - Passage Beds. ee 69 A still more convenient Me for examining the upper part of the Greensand, known as the Cripple’s Path, slants up the cliff, south-east of the village of Niton. The Chioritic Marl, however, Fr. iw lo In. is not seen. At Ventnor the section of the beds is given by Mr. Norman as follows :— Section above Ventnor. Chert Beds, f Alternations of chert and sandstone beds, 21 24 feet. to 24in number - - = = Firestone - é ie Rag ea Bed (bastard i in upper part] - lee Sar isto e , Rag 3 3 Soft sandstone - - - | Black band - - Malm Rock, |} Soft yellow sandstone (“ Whills »y . 81 feet.) Rag ‘ - Compact reddish sendstone - Rag - - - - Compact reddish sandstone - - - Marmillated rag - - | Soft yellow micaceous sands ‘with concretions Dark coloured rag - ‘ | Dark clayey bed - - \ Hed blue chert, with crushed Tnoceramus - Gault Light-grey sandy micaceous clay. = =) CMH SOOM SR TIP LOWE Oe v2 — S on Sromoroooo Pooeocoococe o Near Shanklin in some quarries where the “ free-stone bed ” worked for building, and the beds above and below it for a making, the following sections were noted. Quarry on the south side of the Luccomb Valley. Fr. Alternations of chert (‘‘ shotterwick ’ ) and sand open notseen) 15 Rag in lenticular masses - - O Firestone - - - - - «~ 2 Rag - : - - - - 0 Firestone - - - - - 3 Rag - - - - O Firestone or Rub-stone (a stone formerly used for whitening hearths, &c.) - - - - - - O Freestone - - - - - - 4 Poook me at to RO _ bo on 70 GEOLOGY OF HE ISLE OF WIGHT. Quarry on the north Side of Greatwood Copse. Chert, rag, and sand (top not seen) - - 15 0 Ra g- a 7 - 0 0-6 Firestone - - - - 2 0 Rag - - 4 : 0 0-8 Firestone < 210) Rag - < z Q 0-12 Rubstone - - - 0 8 Freestone . 4 0 Rag - - - 1 0 Inferior stone or malm 5 0 Rag - - I 0 Inferior stone - 3. Culver Cliff: In this section the layers of chert, so conspicuous near Ventnor, are represented hy a few lenticular masses only, or by layers of a hard flinty stone. The freestone also can no longer be distin- guished, and the whole vroup shows a loss in thickness of 18 feet. Culver Cliff. Fr. In. Chloritic Marl (see p. 81), Chert Beds f Green sand with lenticular masses of black and { chert at 9-11 feet from the top, and some Malm Rock. bands of hard grey stone - x00 Gault Passage Beds (see p. 64). INLAND SECTIONS. 1. dlong the Central Downs. Although numerous inland sections lay open the Upper Green- sand, the whole subdivision is rarely expoxed at one spot. An exception occurs in the road-cutting north of Brook, where the following beds are seen :— Roud-cutting three-quarters of a mile north of Brook Church. ; Fr. In, Alternations of chalk and marl {top not seen), passing down - 120 0 Chills dleet Rocky chalk, very impure, and with glauco- nite, passing down - - 5 8 Chloritic Marl, 1] feet inches irregularly hardened into stone in the upper Chert Bed Cio tea Se ert Beds, 2 Upper Jro feat inches. } Cherty lumps in sand - 10 6 [ore sand with phosphatised Ammonites, &c. Greensand, Greenish sand with great len- 107 feet. Malm Rock, ticular and oval masses of 85 feet. rock 85 0 Gault - Passage Beds, not clearly seen, The Chert Beds are seen in a by-road above Dunsbury, and make a small but well-marked escarpment for about 600 yards westwards, The next exposure occurs in the road from Brixton UPPER GREENSAND. 71 to Calbourne where the Chloritic Marl, 14 feet 2 inches thick, abounds with phosphatised Ammonites. The Chert Beds appear also, but the greater part of the Malm Rock is concealed by a thick stratified talus of chalk. Proceeding eastwards we find the Chert Beds at Coombe Tower beginning to form the feature, which becomes so conspicuous in the central and southern parts of the Island. In this neighbour- hood the chert, white in colour and accompanied with much chalcedony, ix exposed repeatedly all along the crest of the escarpment to Shorwell, where it is quarried, or rather dug, for building, East of Shorwell the escarpment becomes steadily bolder, and we find blue chert associated with the white along the crest of the hill. At the east end of this hill, over the Chillerton road, free- stone is worked in a quarry below the Chert Beds, this being the most westerly appearance of the bed so prominent about Ventnor. Between the bold escarpment of Rams Down and the Chalk Downs runs the long winding valley of Chillerton Street, a slight prolongation of which would convert the Chert Beds of Rams Down into an outlier. This valley owes its existence to some springs issuing at the junction of the Greensand and Gault, along the line of a gentle syncline, which is indicated by the relative dips in Rams Down (from 4° to 5°), and in the nearly horizontal Chalk. The trough becomes more marked near Sheat, and in Gossard Hill.* Near the former place the Malm Rock dips north-east at 10°, and the Gault, striking right across the valley of the Medina, runs for nearly a mile eastwards around Rookley, while on the top of the shoulder thus formed, an outlier of Upper Greensand makes a narrow ridge, capped with chert and striking nearly due east and west, with a dip to the north of 8° to 10°. The north side of the syncline is not well defined, as the beds gradually assume a horizontal position. It might perhaps be more correctly described as a monocline, like that of the central axis of the Island, but on a small seale. (Sve also Horizontal Sections, Sheet 43, No. 2.) Numerous old quarries in the Chert Beds and underlying freestone roughen the brow of the hill above Gatcombe and Whitcombe. On mounting this eminence, we find a long dip- slope stretching away westwards to the boundary of the Chalk Downs, which is generally marked by a rise in the ground. In the valley of the Medina near Shide the Upper Greensand disappears from sight till we reach Great East Standen. In two large pits, however, long since completely overgrown, between West Standen and Great East Standen, “malm” is reported to have been dug. So far as can be judged the pits have been opened in the lowest beds of the Chalk Marl. At Arreton, while the topographical feature of the Upper Green- sand is well marked, the Chert Beds no longer form as definite a subdivision as heretofore. The stony bands, to which this feature is * A bold hill near Rookley, so named in the old edition of the Ordnance Map. 72 GEOLOGY OF ‘THE ISLE OF WIGHT. due, seem to come in at a rather lower horizon, while the chert itself is impersistent. The escarpment becomes conspicuous at Knighton, where the dip is gentle, and is separated from the Downs by a deep valley. Some old quarries on either side of the Knighton valley have exposed friable green sand with cherty luraps. The springs previously alluded to (p. 65), issue at the base of the Chalk Marl. The sand is well exposed in a lane at the east end of Knighton East Wood. This brings us to Yarbridge, where there is a fine section in the Chalk Marl, ending, however, at its junction with the Chloritic Marl. The latter can be seen in the sides of the lane which runs along the foot of the Down westwards, while the sand below it is shewn in the lane leading to Morton, 100 yards west of the High Road. The Chert Beds are not distinguishable. East of the Yar the scarped ridge of the Greensand stands out prominently, and excepting a break at Yaverland, continues to do so till it presents on the coast the section which has already been described. 2. Around the Southern Downs. On the west side of St. Catherine’s Down several small pits occur along the scarped brow formed by the chert and freestone, the former material being used for road-metal The outcrop of the Upper Greensand is narrow, but steep, and on the broader slope of Gault lie many huge masses of Greensand that have slipped bodily down, The long flat-topped spur of St. Cathe- rine’s Down which juts out to the north, and marks the line of strike, is capped with a strip of Chert Beds, about 1,300 yards in length, but only from 50 to 80 yards in breadth, and terminates northwards in a remarkable semicircular hollow, which seems to- have been formed by a landslip. The chert is worked for road- metal in small pits here, and on Head Down. West of Niton some old quarries range along the outcrop of the chert and freestone. Another fine brow, known as Gat Cliff, is formed by these beds in Appuldurcombe Park. The dip being southerly, the boldest front is presented to the north. Here also a long line of old quarries marks the outcrop of the freestone. In the valley south-east of Wroxall, along which the railway passes, several sections may be observed. The cutting by whieh the tunnel is approached has been made in the Malm Rock, the Gault, so far as can be seen, lying about the level of the rails. At the south end of the tunnel the rails are abont eighc feet below the freestone; the tunnel descends southwards at the rate of 1 in 173, and is about 1,300 yards in length. From these data it may be calculated that the dip of the strata to the south amounts to 1 in 38 or an angle of rather less than 2°. St. Martin’s Down which terminates northwards in nearly as bold a brow as that of Gat Cliff contains chert bands of exceptional thickness. 73 CHAPTER VII. THE CHALK. INTRODUCTION. Tuts formation extends completely across the Island in an east and west direction from the Needles to Culver Cliff. It may be examined both in the sea-cliffs and in the numerous pits with which its surface is covered throughout the entire distance between those points. It forms a range of elevated undulating hills, conspicuous from afar on account of their altitude, and the bold rounded outline they present to the eye, as well as from their bare and uncultivated surface, which is covered with a short grass, and is rarely used for any other purpose than the pasturage of sheep. In consequence of the high angle at which the Chalk dips throughout the greater part of its range from west to east, the breadth of surface occupied by it is inconsiderable compared with that of most of the strata above and below it, while, on the other hand, its horizontal extension increases in proportion as the inclina- tion of the strata diminishes. For this reason, from Alum Bay to Mottistone Down, and from Carisbrook to Culver Cliff, between which localities the Chalk is nearly vertical, it constitutes a mere ridge of high land, scarcely a quarter of a mile broad in Afton Down. Between Mottistone Down and Carisbrook, where the strata become less inclined, the width of the band of Chalk exceeds three miles. For the same reason, the outliers of Chalk on the south side of the Island between St. Catherine’s Down and Shanklin Down, although of inconsiderable thickness compared with the depth of the entire formation, yet in consequence of being nearly horizontal extend over a comparatively wide surface. Throughout the central range of the Island the dip of the Chalk gradually increases in amount towards its higher strata, becoming nearly vertical at its junction with the overlying Tertiary formations. The well-known rocks called the Needles are large wedge- shaped masses of Chalk standing out in the sea, isolated from the main body of Chalk by the wasting action of the waves upon the coast. 2 0 Marl (? Belemnitella Marl) - 2 O04 The pit is now occupied by forsee biuildtage, and the section somewhat obscured. The nodular bed was first noticed and * Quart. Journ. Geol. Soc., vol. xxi. p. 403. CHALK, 87 ‘described by M. Barrois in 1875.* He obtained from it Inoce- ramus labiatus, Rhynchonella Cuvieri,and Cidaris hirudo. The Chalk Marl appears on the east side of the Gatcombe road, and in an old pit midway between the two described above. On the east side of the valley a large pit exposes the Lower Chalk ; the Middle and Upper Chalk are seen, but not well, in the side of the road. Some fine sections occur at the east end of Arreton Down. On the west side of the high road, in the bottom of a disused pit, Mr. Whitaker found the Chalk Rock. It is now overgrown, but the beds above it are seen as follows :— Fr. In. Nodular chalk with a few grey flints. Smooth chalk with Terebratula semiglobosa, Inoceramus, &c. 2 6 Rough nodular chalk - - - - = 16 4 Fifty yards east of this pit, and on the opposite side of the road> a marl-pit exposes a good view of the Chalk Rock, the section being as below :— Fr. In. ( Smooth chalk - - - - 4 0 | Black clay - - - = 0 1 Upper Chalk < Rough chalk - ! - - 8 6 | Chalk jf Line of green-coated nodules 0 4 Rock { Rough nodular chalk - = 2-2 Smooth chalk - - 2.3 Marl - - - Ol Smooth chalk - - o- 2.6 Middle Chalk? Marl - - O 0% Smooth chalk - - - - 10 6 Marl - - a - 0 3 Smooth chalk = = S - 2 O4 Following the foot of the Down eastwards we find a large pit 300 yards north-west of Heasley Lodge, in the upper part of which a band of rough chalk, nodular in parts, is no doubt the Melbourn Rock. The section is as follows :— Pit on Mersley Down, Fr. In, Massive chalk with marly partings - - 60 0 ¢ Nodular chalk, the top concealed, seenupto 2 0 Melbourn Thin-bedded chalk with partings of greenish Rock. marl - - - - - 40 Hard chalk, nodular at the base = = 3 6 Alternations of chalk and marl - 3.0 P Belemnitella f Laminated marl “ = 2 0 Marl. Marly chalk with curving joints - - 2 6 The pit is worked deep into the Chalk Marl, but the rest of the section is obscured by talus. There is a large pit in the same beds by the side of the Ryde and Newchurch road, but the Melbourn Rock was not to be found. The *Chalk Marl is well seen in a large pit north of Kern. * Craie de l’'Ile de Wight, p. 16. 88 GEOLOGY OF THE ISLE OF WIGHT. At Yarbridge all the subdivisions of the Chalk are exposed. Two large pits are situated on the side of the road to Alverstone, the upper one wholly in the Chalk-with-flints, the lower one partly in this and partly in the Middle Chalk. Pit half « mile west-north-west of Yarbridge. x aon o% Rough nodular chalk, with lumps slicken- sided and weathering yellow ; fossiliferous ip the lower part - - - - White marl parting - - - - Rough chalk with Terebratula semiglobosa - Black clay - Rough chalk - a z | Smoother chalk - - - ls Rock, a single line of green-coated | Chalk with a few grey flints - Upper Chalk COorcrsS nodules lying on - Rough nodular chalk - - Middle Chatk { ee . : OnwWweo AHODOMDM rane ‘The same beds were formerly exposed in Yarbridge in some pits which are now partly hidden by building. Mr. Whitaker noted the following section* :— Chalk with a few nodular flints (shown only at the northern end of the quarry, where it is 20 to 30 feet thick). Thin seam of dark-grey clay. Chalk, about 8 feet. Inconstant layer of irregularly-shaped green-coated nodules (Chalk- rock P) Evenly and massively bedded chalk, without flints, but with seams of mar], The Middle and Lower Chalk are well exposed in a pit about 200 yards west of the upper road in Yarbridge, which shows the following section :— Pit west of Yarbridge. : Fr. In. Massive chalk in beds of 2-3 feet, iron pyrites - - - - - Thin-bedded chalk in beds of 6-8 inches, with partings of greenish marl - Melbourn {tam nodular bed - : : 30 0 Laminated greenish marl - - - Rock. Hard ‘neti bed - si ‘ = Smooth earthy chalk with curvilinear jointing ? Belemnitella passing down into : S Marl. Grey or greenish marl with curvilinear joint- ing passing down into - Hard chalk - - s Marl - - - - Alternations of marl and blocky chalk « 21 We now reach the great section afforded by Culver Cliff. There the sub-divisions are not only well exposed, and the different mOoNW Onto lo Seon OC AWoe * Quart. Journ. Geol. Soc., vol. xxi. p. 404. 1865, CHALK. 89 horizons identifiable, but by choosing the least steep parts of the cliff we have found it possible to take an unbroken series of measurements from the base of the Upper Chalk downwards, thus continuing the measurements which have already been given for all the beds down to the base of Lower Greensand. The total thickness of beds measured in this section amounted to 1,218 feet, as ‘shown drawn to scale in Plate JII. The section in the Chalk is as follows :— Culver Cliff. Fr. [v. Chalk with grey flints - - Smooth chalk with Holaster - 4 0 Chalk, splitting up into nodular masses along wavy dark lines ; Upper Chalk 2 aoe 3 . ; 3 0 Chalk as above - - - - 2 Beds, obscured by talus - 16 Chalk Hard grey chalk, with a line of Rock. green-coated nodules at top - 1 Thick-bedded white chalk with partings of marl - 7163 Shaly chalk - we oo WwW =o oo we Middle Chalk, } Melbourn Chalk split up by panting of 180 ft. 3 in. Rock. greenish marl Chalk with pellenteestied no- 2 Challe with yellow- coated no- dules 0 1 6 dules 2 0 tella Bluish marl, about = 6-0 Marl. ? Belemni- im cr Massive smooth chalk - - 86 0 (‘Thin-bedded grey chalk and marl in numerous pinnae ea) passing down - 50 0 Lower Chalk, 2 Chalk Similar beds, but rather Blier 206 ft. Marl and more marly; the chalk i bands very hard and lumpy, and containing Ammonites varians and sponges abun- dantly - - - 70 0 “Chloritic Mar] (see p. 81). An abstract of this section may be arranged as follows:— Abstract of the Section of Middle and Lower Chalk in Culver Chiff. Fr. In. : Thick-bedded chalk - 166 0 es | Melbourn Rock - - @ = 8-3 *? 1M. | Belemnitella Marl - ; ‘ - 6 0 Lower Chalk, f Massive chalk - 2 - 86 0 206 ft. Chalk Marl - - # - 120 0 386 3 The thicknesses vf these sub-divisions at Punfield compared with those given above, show a westerly attenuation of the Chalk 90 GEOLOGY OF THE ISLE OF WIGHT. as of the other Secondary Rocks. The Upper Chalk becomes devoid of flints but very nodular in the lower 20 feet, and has as its base a conspicuous band of green-coated nodules, about 4 inches thick (Chalk Rock), below which the section runs as follows -— Near Punfield Cove. Fr. IN. Hard, rough, and lumpy chalk - + 690 Smoother chalk, thick-bedded, with partings saci 5 of marl - ce _ i: oon Melbourn Rock - . _- (6 0 ooh Smooth chalk with conchoidal fracture, with several partings of marl - - 30 Fine marl (? Belemnitella Mar]) 9 0 Alternations of chalk and marl in beds of Lower Chalk, 1 to 2 feet, with an occasional line of 132 feet. nodules, some of which are green like those of the Chalk Rock - - 132 0 243 0 2. The Southern Downs. The outliers of chalk, which cap these hills, consist of the Lower, Middle, and a mere film, if any, of the Upper Chalk, the Chalk-with-flints (and according to M. Barrois the whole of the Middle Chalk) having been denuded away. The tops of the hills, however, are so thickly overspread with flint gravel, a residue of the mass of beds that have been removed by subacrial agencies, that it is not possible to say what is the highest bed present beneath this covering. In the outlier of St. Catherine’s Down the dip is at a gentle angle to the east-south-east—that is, about the same as that of the Lower Cretaceous Rocks seen in the coast.* The thickness of chalk forming the outlier amounts to about 180 feet, and must therefore belong wholly to the Lower Chalk. But it is noticeable that the hill is capped with flint gravel, a relic of the Upper Chalk, that must have been slowly let down from above by the dissolving away of the chalk. The best exposures of the beds are to be met with in a large marl-pit at the north end of the outlier. They consist of alternations of chalk and marl generally in thick beds, and are traversed by a small fault running about E. 10° N. with a downthrow to the south. A second outlier, scarcely separated from the first, occurs on the brow of Gore Cliff. The beds, well exposed along the cliff, with the underlying Chloritic Marl, are very fossiliferous. This outlier evidently forms the northern flank of a chalk-hill, of *Tt was stated by Captain Ibbetson that an unconformity between the Upper and Lower Cretaceous Rocks was visible in the Isle of Wight (Quart. Journ. Geol. Soc. vol. iii. pv. 815. See also Judd on the Punfield Formation, 7b. vol. xvii. p. 221, 1871). This statement was founded on «a mistaken idea that the Chalk of the Southern Downs is horizontal, while the easterly dip of 2° of the lower rocks, as seen in the cliff section at \therfield, was supposed to be maiutained beneath them. Neither supposition is correct. CHALK, 91 which the only other traces left are masses of fallen chalk in the Undercliff. Some of the rain-wash, however, from the slopes of this vanished chalk-down forms a conspicuous bed on the brow of the cliff (see postea, p. 237). There is a smail pocket of flint- gravel in this chalk. The same description will apply also to the chalk which caps the cliff cast of St. Lawrence. The Chalk Marl only is seen, but it is possible that the tops of the hills touch the more massive upper beds of the Lower Chalk. The base of the Chalk Marl occurs in St. Lawrence Shute and in the footpath leading up the cliff to Whitwell. The dip is southerly and south-easterly at gentle angle. In the high down which extends northwards to Appuldurcombe Park, there is a thickness of about 270 or 280 feet of chalk at a point between Week Farm and Rew Farm, and there must therefore be from 60 to 70 feet of Middle Chalk on this hill, underneath the gravel. Numerous oid pits have been opened in the Chalk Marl around Stenbury and Appuldurcombe Downs, and a pit is now worked near Ventnor Cemetery, in a more massive chalk, apparently the upper part of the Lower Chalk (the Grey Chalk). Mr. Norman remarks that a portion of the head and jaws of a large fish was dug up in the Cemetery, but unfortunately not preserved.* The junction of the Chalk Marl and Chleritic Marl is seen on the brow of the cliff 900 yards east of St. Lawrence Shute, and in the side of the zig-zag road leading up the cliff above the Royal Hotel, Ventnor. It is exposed also in the cutting ut Ventnor Station, but is more accessible by the road-side, 150 yards east of the Station, and in a road-side 300 yards east of St. Boniface Well. St. Boniface Down forms the highest ground in the Island, reaching a height 787 feet above Ordnance Datum. ‘The base of the Chalk on the north side of the Down is about 450 feet above the sea, and on the south side about 300 feet, the distance across being 1,320 yards. From these data it may be calculated that the southerly dip amounts to 1 in 264, or a little less than oN —a result which agrees with that obtained in the tunnel (p. 72). From the same data it may be calculated that the thickness of chalk and gravel under the highest point of the Down must be about 430 to 440 feet. But it will be remembered that the united thicknesses of Middle and Lower Chalk at Culver Cliff amounted to only 386 feet. Above these there were 26 feet of Chalk Rock and flintless chalk, making a total of 412 feet of chalk below the lowest band of flints. If to this we aid 20 feet for the estimated thickness of flint-gravel on St. Boniface Down, we obtain a total of 432 feet. It would seem then that, though the lowest bed of the Upper Chalk may be present, there is not room for any of the Chalk-with-flints, or at most for more than a mere film of it beneath the gravel. * Geological Guide to the Isle of Wight, p. 99. 92 GEOLOGY OF THE ISLE OF WIGHT. No section, however, occurs of the higher beds forming the Down, with the exception of a small hole on the east side of Shanklin Down, which seems to be in the massive beds of the Middle Chalk. On the very steep slope of chalk over Ventnor a small spring rises, known as St. Boniface’s Well. It was remarked by Sir H. Englefield (op. cit. p. 37) that “a spring at this height, is a most remarkable circumstance, and the only instance of the kind in the whole island. It indicates some stratum within the hill differing from the chalk, which certainly would let the water sink through its substance here, as it does everywhere else.” This spring occurs at about the height at which it may be calculated that the Melbourn Rock and Belemnitella Marl should occur. Division oF THE UvrrrR CHALK INTO ZONES. ‘Che inland section of the Chalk-with-flints presents a remarkable uniformity in lithological character. The sub-division of this great mass by M. Barrois depended therefore principally on the evidence of the fossils, which he collected himself. The following account of the four zones ig an abstract of the description published by him in 1875.* The thickness of the various zones are given by M. Barrois in round numbers of métres. The conversion of métres into feet gives a misleading impression of miauteness of measure- ment. The zones are taken in ascending order. Zone of Holaster planus. For the base of this zone the seam of black clay, described on pp. 87, 88, was chosen by M. Barrois. The zone is seen in the Military Road cutting near Freshwater, as a very hard nodular chalk abuut 65 feet thick. The nodules are of a yellowish-white and very hard, so that it is difficult to detach some urchins, which occur in them. The rock enclosing the nodules is softer, and of a greenish-grey colour; and numerous layers of homo- geneous white chalk with nodules are intercalated. Tabular layers of flint are abundant, and the zone is rich in fossils. At Watcombe Bay, near Freshwater, where the rocks are continually being scoured by the waves, there may be seen in every square yard of the cliffall the fossils characteristic of the lower part of the white Chalk. Zone of Micraster cor-testudinarium, This zone is exposed in parts of the cliffs scarcely accessible, and is rarely quarried inland. It forms the centrai part of the range of Chalk Downs. The thickness is 160 to 170 feet, but is difficult to estimate. The zone is exposed in pits at the west of Bembridge Down, south-east of Brading Down, in the road to the south of the great quarry on Arreton Down, in the road * Craie de l’Tle de Wight, pp. 22-29, CHALK, 93 from Compton Bay to Freshwater and in the cliffs known as the Nodes and the Main Bench. Zone of Micraster coranguinun. This zone has furnished but few fossils; and differences in fauna were not therefore relied upon by M. Barrois in making this sub-division of 500 to 550 feet of chalk. He correlates it with the two divisions established by Mr. Whitaker in the Chalk of the Isle of Thanet, namely the Margate Chalk above, and the Broadstairs and St. Margaret’s Chalk below. In this lower division in the Isle of Thanet he has obtained many specimens of Micraster coranguinum, and in the upper, a great abundance of Belemnites verus, Miller, Marsupites Milleri, Mani., ML. ornatus, Miller, which, according to M. Hébert, are characteristic of the upper part of the zone of Micraster coranguinum. The upper or Margate zone also contains but few flints, while the lower or Broadstairs zone contains a great number. These two zones he considers to be recognisable in the Isle of Wight. To the Margate zone he attributes the chalk of the great quarry on Arreton Down, and of that to the east of Mersley Down; while the Broadstairs and St. Margaret’s type is seen in the small quarry of Bowcombe Down. Zone of Belemnitella. The great quarry to the north of Shaleombe Down shows, in the lower part, white chalk with many large black flints, and, in the upper part, softer chalk with smoke-grey flints. These correspond respectively to the zones known in France as those of Belemnitella quadrata and of B. mucronata. There are many quarries along the north side of the Downs, all in the zone of Belemnitella, but the deepest only reach the horizon of B. guadrata. The flints of the zone of B. mucronata are often grey as at Shalcombe and the Needles, but sometimes black, as at Alvington and Mottistone. In the upper part of the lower zone (that of B. quadrata), Magas pumilus is abundant. ‘The united thickness of these zones of Belemnitella is 260 feet. The junction of the Belemnitella zone and the zone of Aficraster coranguinum may be observed on Arreton Down, but, except in their paleontological characters, there is little difference between them. They are distinguishable only by the relative abundance of flints in the Belemnitella zone, and their almost entire absence in the upper part of the Micraster zone. M. Barrois alludes also to the road-cutting near Apes Down, which extends for some three hundred yards along the junction of the Chalk and Plastic Clay. The section has now become some- what obscured by talus and vegetation, but the contrast between the red clay of the north, and the white chalk of the south side of the road, is still sufficiently striking. 94 GEOLOGY OF THE ISLE OF WIGHT. CHAPTER VIII. EOCENE. INTRODUCTION. Tur Eocene strata of the Isle of Wight may, as a whole, be more conveniently studied in the cliffs in Alum Bay* than in any other part of the Island. In this remarkable section the whole of the strata from the Chalk to the Fluvio-marine formation are displayed in unbroken succession, and that too in a manner the most favourable for close examination, in consequence of their being thrown into a vertical position by the action of the same elevatory force which has caused the Chalk to assume its present high inclination. When the face of the cliffs has been laid more than usually bare, and the colours of the various beds have been heightened by heavy rains, the aspect of the bay, always beautiful, is rendered still more striking. Every bed is then revealed to the eye from the base of the cliff to where it crops out at its summit, and while some of the beds attract the attention by their contrast in colour, others, like the coals in the Bracklesham series, the conglomerate bed dividing that series from the overlying Barton Clay, and the bed of white pipeclay in the Lower Bagshot series which is so crowded with vegetable remains, are not only rendered con- spicuous by their different colours, but, standing out from the rest of the strata, they become useful by enabling the observer more readily to perceive from a distance the positions and limits of the various formations. No drawing without the appliance of colour can do justice to the section, and even then no artist is capable of rendermg a faithful and characteristic representation of it, who does not (like the late lamented Edward Forbes) combine with a dexterous use of the pencil a thorough knowledge of the geological structure of the scene he wishes to delineate. Reapine Bens. Tue lowest member of the Tertiary Group in the Isleof Wight is the Reading Series of Prof. Prestwich, formerly called the “ Plastic Clay” from the occurrence in it of beds used in the manufacture of tiles and coarse earthenware. Owing to the strata being nearly yertical throughout the Island, this division can only be examined at Alum and Whitecliff Bays. Formerly there were pottery works at Newport in the red clays, but the pits are now filled up and overgrown. The only other inland sections now visible are near Brading; in a railway cutting at Ashey; and at Downend Brickyard, near Arreton. The last has been opened since the * So called from the quantities of alum formerly manufactured there. READING BEDS. 95 new Survey was complete, and there has been opportunity of examining it. In the Isle of Wight the Reading Beds consist almost entirely of mottled clays, in “which shades of red and purple predominate. These rest on a slightly eroded surface of the Chalk, and contain at their base small rolled flint pebbles. (Seg Fig. 16, from a sketch by Sir Andrew Ramsay.) Fie. 16, Junction of the Chalk and Lower Tertiary Beds, in Alum Bay. The following section was measured, with the assistance of Mr. Richard Gibbs, in 1852. Section of the Reading Beds in Alum Bay. Fr. In. Red and white mottled clay, with a ferruginous parting at 4feet - - = - - - 25° 0 Ferruginous- brown clayey sand - - - 14 0 Bright- red and white mottled clay fotpadlay) - 20 0 Brown and grey sandy clay (with a bed towards the muddle of dark-red clay 3 feet thick) ; most sandy in re upper 5 feet = - - 10 0 Tenacious, wet, red and white mottled clay - - 3 0 Tenacious blue and brown ferruginous clay - - 8 0 Brown sand covering an uneven eroded surface of Chalk 3to4 0 84 0 As the strata are traced eastward their thickness increases to 110 feet at Downend, 92 feet at Ashey, 140 feet at Brading, and 163 feet at Whitecliff Bay. At the last-named locality they consist principally of mottled clay, but are so hidden by landslips and mud-streams that their details cannot at present be noted and the total thickness here given is taken from the original measurement made in 1852. The section in the railway cutting at Brading is now entirely overgrown, but a sketch and description, ate by Mr. Whitaker during the construction of the line in 1878, is here given. (Fig. "17. ) GEOLOGY OF THE ISLE OF WIGHT, 96 “yeyQ ur pure ‘yynos Toqjyany sadaap st Suryyno ayy, *Avpo oy} our Suyoofoad Apaed ‘Avg unpy ut sv “aorjounl ory ye anov0 syurp Yystpuno. oSny eMOG AL[NGIL yeMowos oq ysnur ynq “UAoYs ApAVO[) Jou sv YyLyO oy} pue spog Surpeayy oy} Jo uoyounl oy, *,08 St Yonut se Suyyno 943 Jo apis (Wdazs¥a) JaYZO 94} UO pue “(09 Jo dip v Surmoys f szuIy yy ypeYD “7 ‘Avo oseyd ajdand pu Aaas umorg “yf | ‘Avy oseyd uosumtas pure Aoi) “ev | “fois payyjour ‘Avo oyseld poy ‘Alo orsv(d uosumI0 pure Ystusetx) ‘Aejo oyseyd Aotd pue uosurn, ‘depo oyserd aydand pue aan ‘pues ouy Adis-yy 51] pur yng ‘dosmIIo popyour ‘Avo oyseid Aars-apdang “Avo Jo stakvy yp ‘Spurs Addvpo auy uMorq pus yng “TOUL UL 0} JaaF OF ‘[VOIAA puL [V}TOZIIOY “y ¥ ‘Spod f s P Surpeay ‘D ‘J YseAy “2 ‘aTeag ‘(apis Susagsaar wo ‘way hry) uoyngs Supoag fo yjnos gsnl Huygny hinnpnyy AT OM LONDON OLAY. 97 Some caution is needed in estimating the true thickness of the Reading Beds in the Isle of Wight; for it must not be forgotten that the strata are nearly vertical and have been subjected to violent pressure, varying in direction and amount according to their proximity to the sharp monoclinal curve which forms such a con- spicuous feature in the geology of the Island. Where the Chalk is thrust northward, beyond the ordinary line of the Downs, the compression of these lower Tertiary strata is also greatly exagge- rated, but where the Downs recede slightly to the southward the thickness of the Reading Beds increases considerably. Allowing for this compression, and taking into account the messurements obtained on the mainland, it seems probable that the thickness we might expect to find in wells sunk beyond the limits of the most violent disturbance would be from 100 to 120 feet. The only fossils this series has yet yielded in the Isle of Wight are fragments of plants; and though the beds are probably in the main of freshwater origin, there is little direct evidence in the district. On the mainland the principal fossils found in Reading Beds of this type consist of leaves of plants and other vegetable remains, showing, according to Sir J. Hooker and Mr. J. Starkie Gardner, a temperate climate. In similar beds at Lancing, however, the mottled clays are not entirely freshwater, for they contain a line of ironstone nodules with casts of marine shells. Lonpon Ciay Like the Reading Beds, the London Clay forms a narrow belt extending across the Island, between the west and the east coast, from Alum Bay to Whitecliff. In consequence of the highly inclined position of the strata between these points, the width of the out-crop of the London Clay, or the space occupied by it at the surface, is frequently very little more than the actual thickness of the formation. The only places where it can be thoroughly examined are on the coast. : The junction of the Reading Beds and the London Clay is sharp and well defined. in Alum and Whitecliff Bays the highest part of the older deposit consists of red mottled clays, while the base of the newer one is ferruginous or blue sandy clay. At both localities the division between the two formations is indicated by a band of flint pebbles, sometimes mixed with pebbles of the underlying red clay, representing the Basement Bed of Professor Prestwich. In Alum Bay, however, this seam of pebbles is not perfectly continuous. Inland, the Basement Bed is better repre- sented by an impersistent bed of fine sand, seen in the road cuttings between Calbourne and Swainstone, and dug near Ashey Chalk Pit and close to Ryde Waterworks. This sand appears nowhere to exceed 10 or 12 feet in thickness. There is nothing especially characteristic in the fauna of these basement beds in the Isle of Wight, all the species being also found in higher zones. E 56786. G 98 GEOLOGY OF THE ISLE OF WIGHT. Junction of London Clay and Reading Beds at Alun Bay. (Observed hy Mr. Whitaker in 1865.) (Grey and brown sandy clay, with here and there a small flint-pebble :—passing down into the next bed. (Grey and brown loam or clayey sand partly with clay-lines and green grains, London Clay < Fa sueute | shells, and hard masses (sometimes bed < concretionary clayey limestone and one ironstone 6 inches thick) + or 44 feet. | Coarse pea-iron-ore 3 inches to a foot {or more. Reading Beds. Grey and crimson plastic clay. Fossils from the Basement-hed of the Loudon Clay in the Isle of Wight. = first noted by Prestwich. W= ,, 5 9 Whitaker. —_— | Alum Bay. | Whitecliff Bay. { Lamna, teeth | P P t i Aporrhais Sowerbyi, Mant. w | P *Calyptrea ? - WwW ' —_— *Fusus W : — Natica labellata, Lam. AV? | P *Pleurotoma - ay — Pyrula tricostata, Desh. - | P Rostellaria ( ? = Aporrhais Sowerbyi) W | = *Solarium = - - WwW *Arca - - Ww —_— Oardium plumsteadiense, Sow. Ww? P Corbula : - ‘ P *Cyprina Morrisii, Sow. Ww W? Cytherea obliqua, Desh. Ww 1p * » orbicularis, dw. ig | sensi *Glycimeris ? - Ww —_ *Nucula a Ww med Ostrea 4 - Pp *Panopea - Ww pes Pectunculus brevirostris, Sow. we P Ditrupa plana, Sow. Pp Pp Wood, &c. - | P * Here recorded for the first time (from the Isle of Wight). The following section was measured in July 1888 with the assis- tance of Mr. Henry Keeping. It continues the upward succession given at p. 95. LONDON CLAY. 99 Section of the London Clay in Alum Bay. Fen. Dark blue loamy clay, with ironstone nodules. Becomes sandy in the upper part - - - - - 46 Laminated dark grey loam —- - - - - 13 Loam, passing upward into fine sand - - - - 23 Blue clay, becoming more loamy above - - - 17 Line of large septaria full of Cardita Brongniatii (a conspicuous bed) Dark blue clay - - - - - - 62 Loam with scattered small flint pebbles. Panopea intermedia, Tellina, Cassidaria, Fusus, Turritella imbricataria, Natica labellata - - - - - - - 2 Brown and bluish clay, with lines of septaria - - - 35 Septaria full of Pinna affinis (a conspicuous bed) - - Brown and bluish clay, sandy in places, with lines of septaria 20 Basement Bed—Sandy glauconitic loam with a little pyrites. Ditrupa at the base - - - - - 15 Totai - - - 233 Other measurements made the total 200 feet and 220 feet. Here again it must be observed that no reliance can be placed on the minute accuracy of the measurements, for the top of the cliff will give a different result from its base. If the monoclinal curve of the Isle of Wight be carefully plotted and measured, it will be seen that the upper aud under surface of any bed affected by the disturbance cannot always be parallel, but that the thickness will vary according to the part of the curve at which it is taken, and also according to the hardness or softness of the beds affected. At Whitecliff Bay the basement pebble-bed, two inches in thick- ness, is overlain by eighteen inches of buff-coloured sands, above which there lies a bed of hard sandstone, abounding in Ditrupa plana, that appears on the shore and may be seen stretching out to sea, for a considerable distance, at low water. About thirty-five feet above the basement bed there occurs a zone of Panopea intermedia (Fig. 19), and ria, 18. Pholadomya margaritacea (Fig. 18), ria, ! ny g g Pholadomya margaritacea with their valves closed; at fitty feet a > another band of Ditrupa plana (Fig. 20) comes in, and at about eighty feet there is a well-marked band of Cardita. The remainder of the section in Whiteclitf Bay consists, in ascending order, of lignite in dark-grey clayey sand, aluminous and weathering to a brown colour; ferruginous-brown sapds; clayey sand or sandy clay as before, but darker, harder, and more clayey than the beds below, and containing Panopwu intermed:a, we 100 GEOLOGY OF THE ISLE OF WIGHT. Fia, 19. Fie. 20. Panopea intermedia, Sow. Ditrupa plana, Sow. with their valves joined, lying in the positions they occupied when alive. Succeeding these, are similar beds with sandy alternations and laminz, and « layer of large septaria. Pinna agfinis (Fig. 21) is found in the septaria.* The total thickness of the London Clay amounts to about 320 feet. A bed of flint-pebbles is found at 255 feet above the base. Fic. 21. , ees Pinna affinis, Sow. No inland sections of the London Clay are now visible in the Tsland, unless the cutting at Ashey is partly in this division. Probably, however, the clays there exposed belong almost entirely to the Bracklesham Beds, nearly the whole of the London Clay being cut out by a strike fault. The fossils of the London Clay (see Appendix) lave not yet been fully collected in this district; but as far as they go they indicate a subtropical climate, ag in the London Basin. The occurrence of occasional scattered lines of flint-pebbles in the clay is noteworthy. ‘This and the more sandy nature of the strata seem to point to a gradual shoaling of the sea towards the south, at the time when the London Clay was in course of being deposited. E * See also Caleb Evans, On the Geology of the neighbourhood of Portsmouth and Ryde. Proc. Geol, Assoc., vol. IL. p. 70. (1871.) LOWER BAGSHOT BEDS. 101 Lowrr Bacsnor Bens. In 18t7 Professor Prestwich* pointed out that the series of sands and clays between the t.ondon Clay and the Oligocene Beds in the Isle of Wight is the equivalent of the Bagshot Beds on the mainland. He also showed that in the Isle of Wight there is a similar three-fold division—into Lower Bagshot, without fossils; Middle Bagshot, with marine fossils like those found at Bracklesham ; and Barton Clay and Sands, the last two perhaps being equivalent to the Upper Bagshot of the London Basin, perhaps in part (the Barton Clay) dying out northward, or passing into the middle division. Subsequent research—especially the observations of the Rev. Osmond Fisher—has added largely to our knowledge of these strata and their fauna; but there is still considerable doubt as to the exact limits of the divisions, which in fact pass almost imperceptibly into each other. Recent observations have also indicated that the Upper Bagshot Beds in the London Basin are probably the equivalent of the lower part of the Barton Clay in the Hampshire area ; and that the glass-sands (the so-called Upper Bagshot Series of the Isle of Wight) belong to a higher zone, apparently unrepresented north of Hampshire. Owing to the Bagshot Beds being nearly everywhere vertical, it has been found impracticable to trace their subdivisions on the map, especially in the absence of fossils. The whole series has therefore been grouped together, represented by one colour, and indicated on the map by the letters i 4 to i'7. In this Memoir the term ‘Bagshot’ is only applied to the plant-bearing pipe- clays and sands formerly called ‘ Lower Bagshot.’ These Lower Bagshot Beds are highly developed in the Isle of Wight, attaining a thickness of 660 feet in Alum Bay. But it may be well at once to point out that part of this great thickness of sparingly fossiliferous beds may be the equivalent of the lower part of the marine Bracklesham Beds, which appear to thicken so greatly towards Whivecliff Bay. Lower Bagshot Beds in Alum Bay. Fr. In. Very thinly laminated pale yellow sand - - —- 100 White crimson, and rose-coloured variegated sand passing into pale brownish-yellow sand = - - - = 0 Thinly laminated light grey pipeclay - = 1 6 Pale yellow sand and white laminated clay, with crimson | streaks. 2 hat Details of the upper part of this subdivision :— Fr. In. | Yellow sand - - - -14 6 Ling o Pipeclay parting - - - we eS White sand - . - - - i 6 Yellow sand - - - «120 White and crimson sand - - . -J * Quart. Journ. Geol, Soc., vol. iii. p. 386. 102 GEOLOGY OF TILE ISLE OF WIGHT. Fr. Thinly laminated clay, chocolate-coloured in the upper part. Details :— Fr. Iv. Clay - - - 27 ~«0 Tig nite (very hivaninous) - - - 0 6 Clay, with a band of lignite 5 or 6 feet from the > 99 base - - 44 0 Thinly laminated yellow iailebene, with much carbonaceous matter - 4inchesto 0 6 Clay ; white, hard and marly - - 27 0 J ‘Tawny, variegated, pink and white sands, with brown lamin : white sand predominates. 90 (Iron bands 1 inch thick occur at 52 feet anil 79 leat trom the bottom) - - Pale grey and yellowish-brown sands, with fin isattian of a) darker grey clay, vonitaining pyrites and carbonaceous | matter (Some of the laminz, when or broken, are of a greenish © colour. These beds are darker and most laminated in the lower part, and are most sandy towards the upper part) | lught grey sandy clay, with vepetabls matter lying across the bedding - 2 Fawn coloured and whitish sands, slightly “variegated with red: the upper 10 feet slightly laminated. Details :— Fr. In. Slightly laminated white sand Trony band - - - Ol Ms 40 White, pink and yellow laminated sand, with veins of white pipeclay Ba bright red lamine of iron - + 7 6 Fine light yellow sand - - - 23 0 |) Pipeclay (full of leaves) between yellowish-white and varie- gated laminated clays. The lower 2 inches are composed of sandy white pipeclay, with laminz of yellow and crimson sand, becsmping thicker towards the upper part of the cliff - s 2 6 Bright yellow sand, with thin laminza of blue clay 13 Tron band - 2 - 2 Grey and yellow sands. Details :— Fr. In.) Yellow and grey sands - - - 15 0 Grey laminated sands and clays; mostly sands 18 0) Do. nearly all > 45 clay : very carbonaceous : - ll 0 Grey Jaminated sands and lays clay predomi- nating - - - 3 °4«G Iron sandstone band and tawny ironsand with ferru- ginous veins and strings, and pebbles of quartz -0 6 to 3 Grey sands, &c. » Details :— Pale yellow and bluish white sand, darker in the upper part and with a few lamin of clay 16 0 Blue clay with thin (¢ inch) sandy tamine ; r lod carbonaceous matter 7 -27 0 Grey and yellow sands, with thin lamines of blue clay; much pyrites and carbonaceous matter - - - 61 0 J N.B.—These beds have a slightly reversed dip towards the don of the cliff.) Bright yellow and white ‘sands, more laminated and clayey than the bed above, and containing much carbonaceous matter. ‘The lower 5 feet sand x 5 = 4 Iron sandstone 7 3 Parting of pale clay of canal thickness - - “ 0 In. 6 ovo Lot LOWER BAGSHOT BEDS. 103 Fr. In. Very thinly laminated white and yellow sand - 1 10 White sand and blue clay, becoming more clayey towards the lower part. 5 0 [On London Clay.} 662 6 At the eastern end of the Island the Bagshot Beds present a different aspect. The mass of white pipeclay has there disappeared, and the beds have either thinned from 600 feet to about 100 feet, or the upper portion has become somewhat marine and is inseparable from the Bracklesham Beds. The junction between the London Clay and the Bagshot Beds is clearly shown in Whitecliff Bay, the former being represented there by ferruginous brown clay, and the latter by pale grey sands weathering nearly white and containing occasional thin lamin of pipeclay. Thirty-seven feet of these sands, clays, and pipeclays intervene between the upper part of the London Clay, and a band of sandstone that runs out to sea at the base of the yellow micaceous sands which constitute the greater proportion of the Lower Bagshot series there. Above them there is an 18-inch band of flint pebbles, taken by Mr. Fisher as the base of the Bracklesham Series, for in the clay immediately nbove marine shells occur. The inland sections are of little interest, none of them being fossiliferous or showing satisfactorily their relation to the over or underlying deposits. Commencing at the west end of the Island, we find the sands well exposed in pits around Freshwater, especially in one close to Easton, and another on the opposite side of the marsh near some new houses. At the latter there are seams of pipeclay. The road cutting south of Farringford House also shows a good section of ferruginous sand. Continuing eastward, we learn that pipeclay was formerly dug ina piece of rough ground half a mile east-south-east of East Afton. Due north of this old pit sandy white clay is again seen in the deep channel cut by a small stream north of the high road. This is probably a higher seam—perhaps in the Bracklesham or Barton Series. About a quarter of a mile east of Chessel a pit has been dug in sand with the bedding vertical. Between this pit and the London Clay a number of flint pebbles are ploughed up in the field, but it is not atall clear from what bed they are derived, though they seem to occur low down in the Bagshot Series, possibly at its base. ; Continuing along the high road, we come to a deep cutting in sand with seams of pipe clay between the two entrance lodges belonging to Westover. Similar beds occur in the road to Shalfleet, about a quarter of a mile north of Calbourne. Higher beds are exposed in a small pit half a mile north-east of Calbourne, where sand with a dip of 40° is overlain by a bed of pebbles, and that again by clay. Probably this pebbly bed marks the base of the Bracklesham Beds. A few chains further north there are a nunber of old sand pits close to Five Houses. These were 104 GEOLOGY OF THE ISLE OF WIGHT. probably opened in the glass sands of the Barton Series, but no section can now be seen. From this point eastward no sections oceur till Newport is reached. Here the brick-yard near St. John’s Church shuws at its southern end sand, with the bedding vertical. Wells in Elm Grove reach the same bed and a house at the corner of Elm Grove and the main road, is built on the site of an old sand pit. From Newport to Downend nothing is seen of the strata, the slope being much masked by a wash of clay and flints from the higher ground to the south. At Downend, however, the beds were well seen in a small pit in Saltmoor Copse, where clay rests on a bed of pebbles overlying fine buff and red sand, the whole dipping north-north-east at 80°. The pebble bed, which perhaps forms the base of the Bracklesham Beds, is apparently only 150 feet above the London Clay. The Bagshot Beds must therefore have rapidly thinned out eastward, or else the beds of pebbles come in on different horizons in different parts of the Island. As the position of this pit necessitated the cartave uphill over a bad road of the sand needed in the brick-yard, it was pointed out by one of the writers that the same bed would be found close to the kilns, underlying the brick-earth. The pro- prietor has consequently opened a new sand pit since the survey was made, and probably the section above described will now be overgrown. At Brading Station the sands are again seen, and they re-appear in the bluffs on the eastern side of the Yar, but without any clear section. A few chains further east, close to Longlands, a pit shows a dip of 95°—z.c. reversed 5°—to the north-cast. Very little is yet known of the fossils of the Lower Bagshot Beds in the Isle of Wight, except the plants, for it is doubtful whether any other organic remains besides elytra of beetles have been found in this series. Own THE Frora oF Anum Bay. By Mr. J. Srarxir GarRpner, F.L.S., F.GS. The plant remains were found in a pocket or lenticular thickening of a seam of fine white pipe-clay in the midst of the Lower Bagshot Sands. They consist principally of most delicate impressions of leaves, rarely presenting traces of colour, and giving little indication of their texture when living. They lie with the planes of bedding and are rarely twisted or rolled. The leaflets of compound leaves, of which there are many, are almost always detached, though a few specimens exist in which they still adhere to the axis. With the leaves are twigs of a conifer, shreds of fan-palm and reed, small leguminous pods, drupes and other bodics too decomposed for identification, and very rarely, a flower like FLORA OF ALUM BAY. 105 Porana or Kydia, and the detached elytron of a beetle. All bear the appearance of long immersion and tranquil deposition, and the sediment is so fine that the disturbance in it caused by the forma- tion and passage of gas bubbles is distinctly visible. very irace of carbon has been chemically removed. This pocket must have been of considerable size, for it was known to Mantell as far back as 1844, and it continued to yield specimens of leaves abundantly down to about 1883, when they became rare, while at present scarcely any vestige of leaf-bearing pipe-clay can be found. The number of species obtained from this pocket has been variously estimated. The first critical examination of the flora was by De la Harpe in 1856, when out of 48 species seen, 43 were pronounced determinable and uamed specifically. Of these 21 of the most important were figured in the former edition of this work. Heer added a species in 1859.* Ettingshausen in 1879 spent a winter in studying collections from Alum Bay, and announcedt that the flora comprised 274 species divided among 116 genera and 63 families. Like Heer, he found considerable affinity between these and the flora of Sheppey, and further called atten- tion to the community of more than 50 species with the floras of Sotzka and Haring. We are not able to reconcile this estimated richness with our knowledge of the flora, and surmise that fossil plants from other localities must have been inadvertently included. The flora appears indeed, very restricted as to species, as we might reasonably anticipate, since we are limited to the leaves which drifted waterlogged into a single pool. The most con- spicuous and typical of these are unquestionably the Ficus Bower- bankii, De la H., Aralia primigenia, Heer, Dryandra acutiloba, Sternb., D. Bunbury?, De la H., Cussta Ungeri, Heer, and the fruits of Cesalpinia, It is not certain that these determinations are generically accurate, and indeed one of the latest specimens dis- covered proved conclusively that the Dryandra acutiloba is actually a Comptonia; but they are all well-defined species, and as such form exact bases for comparison. These, with a number of less common but scarcely less conspicuous forms, unite to give the flora of which they are the chief elements, a very special and singularly early impress, so much so that Prof. Newberry would regard them as Cretaceous, if their horizon were not stratigraphi- cally defined. The floras which it chiefly resembles are, firstly, that of Monte Bolea, as already noticed by Heer, and secondly, in a far higher degree, the flora of the Gres du Soissonnais, which though resting on the lignites of Woolwich age in the Paris Basin, are really unconformable and doubtless contemporary with our Lower Bagshot. The chief cause of the highly distinctive and interesting character of the Alum Bay flora, lies in the fact that it is the * Flora Tertiaria Helvetiz, vol. iii., fol. Winterthur, (p. 315, Drepanocarpus Dacampii, Mass.) } Proc. Royal Soc., vol. xxx. p. 228, 1880. 106 GEOLOGY OF THE ISLE OF WIGHT. most tropical of any that has so far been studied in the northern hemisphere. Following so immediately the flora of Sheppey, with its wealth of Palm fruits, some denoting the largest species, it presents us probably with an insight into the dicotyledonous vegetation which accompanied them. Sifted ay they have been by the agency of water, only those leaves and bodies endowed with certain powers of flotation were able to drift to that point; the heavy palin leaves and fern fronds, and the large leguminous pods which vive the Lower Bagshot flora its tropical aspect, have been eliminated. These were left in higher reaches of the stream, and we meet with them at Studland, where large quantities of Fern and Palm are massed together, and at Creech Barrow near Corfe, where the most magnificient opportunities for collecting fossil plants have passed away, never perhaps to recur.* The Reading flora has an exceedingly temperate facies, and thus presents to us a relatively recent aspect. The Woolwich flora is less temperate, for Palmettos appear in it. The Lower Bagshot flora is like that of the London Clay, decidedly the most tropical. The Middle Bagshot flora begins to lose its tropical elements, and these appear to drop out very gradually and without any sudden changes, down to the close of the Hamstead period, when all traces of Eocene plants disappear from this country. Allowance must be made for the facet that Jocal accumulations will of course present very different appearances and plant remains derived from a sheltered and swampy station will appear luxuriantly sub-tropical, which are not so, and conversely, leaves blown from an arid spot may seem to indicate a harsher climate than actually prevailed. The break between the London Clay flora and those which preceded it, is very great, and obviously due to a consider- able increase of temperature. he connection between that of Sheppey and of Alum Bay, though probably a good deal over- estimated, is likewise due, it appears, to the high temperature having been maintained, bringing in a vegetation that bad not been able to exist so far north since the close of the Cretaceous period ; whence the Cretaceous aspect that has struck so many observers. The break, which is very great indeed, between the floras of Alum Bay and Bournemouth, deposited as they must have been under very similar conditions, is far less easy to explain. It is not one altogether of temperature, because there are still many large palms in the latter, as Lrturteu, Phenix, Culamus, Nipa, with decidedly sub-tropical ferns. Some break or change must have driven the then indigenous flora almost completely away and brought in the new set of plants which * There are still fragments, some of them two feet in diameter, of enormous leaves of fan palms, which might casily have been extracted entire, ani parts of huge pods of Cassia and Acacia, preserved in the Dorchester and Jermyn Street Muscums and in private collections ; but for upwards of 20 years no leaf deposits of Lower Bayshot age have been found. The beds at Creech are much folded and leaf beds of Middle Bagshot age are preserved in the folds, from one of which the large series in the Oxford Museum must have been obtained, and from othcrs I have more than once myself been able to collect.—J. 8. G. FLOWA OF ALUM BAY. 107 maintained themselves and spread over central Europe, only dying out or giving way in late Miocene times. ‘Ihis is why the Flora of Alum Bay is of such immense interest 2nd importance, why its composition is so different from other Eocene floras, and why it is confined to a single horizon. Misled by its striking facies, togcther with that of the flora of Monte Bolea, which resembles it, and being unacquainted with any other type of Kocene flora, Heer set it up ax a sort of test flora, determining according to the degree in which other floras resembled it, whether they should be classed as Eocene or not. ‘Thus the floras of Mull and Bovey were discarded from the Eocene, ax those of Reading and Bournemouth would have been had they been adequately known at the time. For the same reason the representatives of the Bournemouth flora on the Continent, became his type of a Lower Miocene (now Oligocene) flora. In the present state of our knowledge no real analysis of the Alum Bay flora is possible. It is remarkable for the absence of any well authenticated ferns, except the pinne of a still some- what doubtful Marattia. Anemia subcretacea, Sap., has been recorded only as Asplentum Martinsi by Heer. As it is common in the Reading Beds and again in the Bournemouth Beds and could evidently support a high temperature, its occurrence would not be extraordinary in the Lower Bagshot Beds, but requires confirma- tion. Chrysodium lanzeanum, Visiani, which alyounds in the corre- sponding pipe-clays of Studland, has also been recorded, probably erroneously, from Alum Bav. Of Gymnosperms the Cupressites elegans of our former edition has been transferred to the genus Podocurpus. ‘Two specimens have revealed traces of fruit, but of too indistinct a character to be very reliable. The foliage greaily resembles that of Glyptostrobus which occurs plentifully in the Reading Beds beneath and the Bournemouth Beds above. There appear to be no other Conifer in the flora. Of Monocotyledons none whatever are determinable unless it be a very doubtful and unique orbicular leaf something like a Smilax. Palms are repre- sented by a few macerated fragments that may have come from the fringe of a leaf such as Sabal, and Reeds by almost equally unsatisfactory fragmeuts of sword-shaped leaves, The Dicoty- ledons are probably between 40 and 50 in number, of which almost all the most characteristic are absolutely confined to the Lower Bagshot horizon in this country. A dwarf leaf of a similar Aralia was once found in the highest Woolwich beds at Lewisham, and twice the Dryandra (Comptonia) acutiloba has been found in a small patch of pipe-clay low down in the Bourne- mouth beds, on the last occasion in the presence of that dis- tinguished paleobotanist M. de Saporta. Some of the most ordinary types of leaves look as if they may be common to other formations, but no importance attaches to them, and with the ex- ceptions just alluded to no strikingly well-marked leaf of either the Woolwich, Reading, or Bournemouth series is known to be common to the Alum Bay flora. The wealth, greater than is supposed, of leguminous plants is one of its chief characteristics, and next in order, are the large leaves ascribed to Ficus. The 108 GEOLOGY OF THE ISLE OF WIGHT. abundance of the single species of Aralia and of a larger Acer furnish a higher proportion of palmate leaves than we are accustomed to in later Eocene strata. There are the usual simple laurel and willow-looking leaves, most of which afford no characters on which we can ever base any valid determinations. The question as to whether there are any true Proteacew in the flora ix still insuspense. There are several forms of leaves in this remarkable family which are quite unmistakable, but none of these have been found fossil in Europe. Nor have any unmistakably proteaceous fruits yet been discovered, even among the tens of thousands that have been collected at Sheppey, where they most certainly must have been met with, for the supposed Petrophiloides ix proved to be an Alder.* The Australian elements in the Tertiary at one time thought to be so preponderant, grow more and more doubtful when critically examined, and it appears that it is rather to Central America on the one hand, and the Malayan Archipelago on the other, that we must look for species nearly related to those of our Alum Bay and Bournemouth floras. That there are some Australasian species cannot be questioned in presence of the Bournemouth Araucariv, and the Hordwell Athrotaris, but these Gymnosperms may well be of immense antiquity and once perhaps universal, so that their occurrence here or in Australia is of little importance. The study of Dicotyledons would alone show whether any part of the existing Australian flora had ever migrated across Europe or America, as the existing Japanese flora has most certainly done, and that study, too long postponed, will, it is to be hoped, shortly be continued in the pages of the Paleeontographical Society. ProvistonaL Lisr of the Fiora of the Prer-cuAy of ALUM Bay (revised by J. SrarKig GARDNER). Apeiobopsis Symondsii, De ia Harpe. Ayalia primigenia, De la Harpe. Cesalpinia emula, Heer. ——-—— Bowerbankii, De la Harpe. ——-—— brevis, De la Harpe. mollis, De la Harpe. —_—-—— Salteri, De la Harpe. -__-—— phaseolites, Unger. ——-—— Ungeri, Heer. Ceropetalum myricinum, De /a Harpe. Chrysodium lanzeanum, Visiani. Cluytia aglaizfolia, Mess. 6 Web. Comptonia acutiloba, Brong. Cornus, sp. Cupania, sp. Dalbergia Salteri, De la Harpe. Daphnogene anglica, Heer. ——-—— veronensis, Massal. Diospyrus, sp. Drepanocarpus Dacampii, Wassa/, Dryandra Bunbury, De /a Harpe. Eleodendron Heerii, De la Harpe. Ficus Bowerbankii, De Ja Harpe. Forbesii, De /a Harpe. Granadilla, Massai. Morrissii, De la Harpe. Grevillea La Harpii, Heer, AIS. Juglans Sharpei, De Ja Harpe. Laurus Forbesii, Unger. Jovis, Unger. ——— primigenia, Unger. — Salten, De la Harpe. Marattia Hookeri, Fert. & Gardner. Podocarpus elegans, De la Harpe. eocenica, Unger. Quercus eocenica, De /a Harpe. ——-—— lonchitis, Unyer. Rhamnus densinervis, Heer. ————_ 3 sp. Sapindus, 2 sp. Smilax, 2 sp. n. Zizyphus integrifolius, Heer. vestustus, Heer. * J.S. Gardner, On Alnus Richardson’, Journ, Linn. Soc., vol. xx. p. 417. 109 CHAPTER IX. EOQCENE—continued. BRaCKLESHAM AND Barron Brps AxBoveE the Lower Bagshot Beds a variable series of sands and clays with lignite attains a thickness of about 700 feet. There is no clear line of division between this scries and the underlying leaf-bearing beds, but the separation is often made at the point where a pebble bed occurs, or at the lowest point where marine fossils have been found. It should be remembered, however, that there is no evidence of any real break, and that the change is so gradual that it is very doubtful whether we have really taken the boundary even approximately at the same horizon at opposite ends of the Island. The difficulty of following the beds inland makes it impossible to connect the sections by tracing the boundaries on the Map. The beds now to be described are often known as the Middle and Upper Bagshot series, but recent observations have shown that the Upper Bagshot Beds of the London Basin are probably the equivalent of the Barton Clay (i.e. of the so-called Middle Bagshot of the Hampshire Basin). It has therefore been thought safer to drop these names and simply to call the groups—for the present at any rate, and having regard only to the Isle of Wight— Headon Hill Sands, Barton Clay, and Bracklesham Beds. BrackLEsHAM BeEps. In 1847, Prof. Prestwich showed that the marine bands over- lying the unfossiliferous Lower Bagshot Beds of Whitecliff Bay were probably equivalent to the fossiliferous Bracklesham Beds so well seen near Selsey.* Subsequently the Rev. Osmond Fisher worked out the paleontology of the beds in greater detail, and the following account of the sections at the two extremities of the Isle of Wight is mainly taken from his paper.t The Bracklesham Beds are represented in Alum Bay by clays and marls in the lower part, by white, yellow, and crimson sands in the middle portion, and by dark sandy clays with numerous impressions of fossils in the upper part. The latter alone have been attributed to the Bracklesham Beds in Mr. Fisher’s Memo. The lower beds are remarkable for the quantity of vegetable matter contained in them, not, however, in the shape of leaves, as is the case in some of the Lower Bagshot Beds, but in the form of coal (lignite), constituting solid beds from fifteen inches to two feet three inches thick. Four of these beds, when * Quart. Journ. Geol. Soe., vol. iii. p. 385. (1847.) ¢ Lbid., vol. xviii. p. 65. (1862.) 110 GEOLOGY OF THE ISLE OF WIGHT. fully displayed, are conspicuous objects in the cliff, where they project out of the softer strata, and on the shore, owing to their black and coal-like appearance. At the time of our survey these beds of coal were more than usually well displayed in consequence of the prevalence of long continued wet weather having worn away the soft intervening strata in which they are imbedded. On examining them during a brief visit made to the Island, in company with Sir A. Ramsay, during the autumn of 1860, it appeared evident that the beds in question occur in the manner of ordinary coal. Like true coal, each bed was based upon a stratum of clay, containing, apparently, the rootlets of plants, as in the underclay of the Coal Measures. The underclays, which occur beneath beds of coal of Carboniferous date, are thought to have been soil that supported the vegetation which, by certain chemical changes, became subsequently converted into coal: it is reasonable, therefore to infer from the presence of similar underclays beneath the coal in the Bracklesham Beds at Alum Bay, that the plants out of which thal coal was formed grew on the spot, and were not drifted from elsewhere, as was the case with the vegetable remains in the pipe-clay beds of the Lower Bagshot Series. A similar underclay was visible in Whiteclift Bay in December 1886, but, owing to the coal having been worked a few years before as far as it could be conveniently reached, the seam itself could not be examined or measured, though a sketch of the roots was made, On comparing the section of the Bracklesham Beds in White- cliff Bay with the corresponding section in Alum Bay, it will be seen that the beds are much better developed in the former locality than in the latter. It is, therefore, at the eastern ex- tremity of the Island that these deposits may be studied to the inust advantage. Indeed, this is the only locality in the country where the entire series can be seen exposed to view. The follow- ing section is taken from Mr. Fisher's paper.* Section of the Brackleshum Beds at Whitecliff Bay. No. I. is the lowest of the series occurring towards the south end of the Bay, and No. XIX. the highest of the series further to the north. The letters a bc, &c., denote the more important fossil-beds, Nos. in | Woes Fisher’s wich’s =—= Feet. Section. Section.t \ f NIX. | ( 17) | « Greenish and blue clays - < = | 162 At 24 feet from the top isa band of small shells im- | perfectly exhibited. Ostrea tlabellula. Cardita, a small species like Mytilus, a smal) species. C. oblonga, © Quart. Journ. Geol. Soc., vol. xviii. p. 67. (1862.) q Ihid., vol. ii. p. 223. (1846.) BRACKLESHAM BEDS. 111 sin | Nos. in Fisher's) Brest: a3 Heh Seotion. | soction. XVUI} (16) Dark-blue clay, weathering brown -| 22 XVII.| — | & Nummulites variolarius in blue clay. The clay is crowded with Nummulites, which are often black 10 ‘Curbinolia sulcata. Pecten corneus. Nummulites variolarius. Cassidaria nodosa. Quinqueloculina Haue- Pleurotoma inflexa. rina. plebeia. Alveolina sabulosa. — scalarata. Rotalia obscura. —— Fisheri. Fusus longeevus. Voluta nodosa. pyrus. Cardium parile ?. Mitra parva. Lucina P. —- var. Cardita planicosta. - labratula. Crassatella (the species found Turritella sulcifera. also at Brook). Dentalium politum. Corbula pisum. striatum P. cuspidata. Rissoa cochlearella. XVI. | (15) | ¢ Light-coloured sand, with two beds of sand-rock. Tel- dina and small Univalves in the bottom of the lower rock - - - 6 Natica. ‘Tellina donacialis. T. plagia. (This stratum forms a good horizon of reference being distinct in character and noticeable.) XV. | (14) Sandy clay, passing into lead-coloured compact clay | 10 Echinoderm in sand. Ancillaria canalifera in clay. ATV. — | d Dark sandy clay, with grains of black sand, full of Corbula pisum in the upper part, and with numerous shells below; passes into dark clayey sand with Pecten corneus - - - - 3 Nummulites variolarius Turritella imbricataria. (common). sulcata. Rostellaria sublucida. = Ditrupa plana. Murex asper. Pecten corneus. Fusus pyrus. Pinna margaritacea. Strepsidura turgida. Nucula Dixoni, Edw. MS. Cassidaria nodosa. Leda. Pleurotoma plebeia. Crassatella (the Brook Voluta nodosa. species). Selseiensis. Corbula pisum (abundant). Cerithium __tritropis, costata. Edw. MS. Cytherea lucida. Calyptreea trochifor- Cultellus. mis XL | — Beds not exposed ; apparently clays 39 XIU. —_ Streaked, whitish-yellow, and foxy sands - 10 XI. — | e Sandy clays, weathering grey and yellow. There is a layer of casts of shells where it passes into the next bed, Sanguinolaria Hollowaysii being extremely abundant - - - - - 4 Turritella sulcifera. Cytherea lucida. Pecten corneus. Sanguinolaria Hollowaysii. Pectunculus pulvinatus. Solen obliquus. X. _ Sand, weathering vellow and grey - ‘ 112 GEOLOGY OF THE ISLE OF WIGHT. sy | Nos. i Fisher's Prest- eae Feet, Section. Pid i IX, | (13) | f Brownish sandy clay, with shells and pebbles at the bottom. The shelly layer appears to be a lenticular mass, and not to be persistent - - - 6 Nummulites variolarius. Ostrea zonulata ?. Murex minax. Arca. Voluta nodosa. Pectunculus pulvinatus. Turritella imbricataria. Chama gigantea. sulcifera. Crassatella compressa. Natica labellata P. Cardita planicosta. Nucula subtransversa P. Corbula pisum. : Tellina plagia ?. Sanguinolaria Hollowaysii. Pecten 30-radiatus. VIR. | (12) Foliated, dark, sandy clays, weathering brown ; with vegetable matter interspersed. ‘There is a layer of casts of shells at the junction with the next bed - | 46 VIL. — | g Green sand, in which Sanguinolaria Hollowaysii is very abundant - - - - 15 (Nummulites levigatus occurs in a mass four feet from the bottom.) Nummulites levigatus. Sanguinolaria Hollowaysii. VI. | (11) | & Light-and dark-coloured green sands, with many shells in the upper part. (A spring at the base of the cliff) - - - - - -} 62 Nummulites levigatus. Pecten corneus. Fusus longevus. Mytilus. —— pyrus. Nucula. Voluta nodosa. Leda. spinosa. Lucina. Pleurotoma dentata. Cardita planicosta. Natica (small). Tellina plagia. Tuwrritella sulcata. Sanguinolaria Hollowaysii. sulcifera. Solen obliquus. terebellata. Corbula (? Gallica). Calyptraa trochiformis. —— pisum. Vv. | (10) Laminated grey clay, with some beds of calcareous green-sand, and a few beds of lignite - 76 IV. (9) k Calcareous, clayey, green, and iron sand, with numerous shells in seams. The base seems washed into the next bed - - - . 2) RS Nummulites ievigatus Calyptraa trochiformis. (rare). Ostrea flabellula. Fusus pyrus. Cardita planicosta, Metula (Buccinum) Cytherea lucida. juncea. C. suberycinoides, Pleurotoma (small), Tellina. Voluta nodosa. Panopeea. Natica, Corbula pisum. Turritella imbricataria P. Ill. | (8) Alternating beds of green sand and finely laminated clay, weathering grey and brown; with thin seams of lignite - - - ‘ . 1s Il. (7) Yellow sand - - . 2 2 -| 10 BRACKLESHAM BEDS. 118 Section. ee cee Feet. I (6) Sandy clay, weathering grey and brown, finely-lami- nated with yellow sand. There are casts of bivalve shells in a band of clay at the bottom. It is based on from 10 to 18 inches of black rounded flint pebbles, often as large as swans’ eggs - -| 95 Total thickness - - 653 The fossiliferous beds marked (2), (d), and (f) are very persistent at the various localities where one or another portion of the series is exposed. It is from them that the many splendid collections of fossils have been obtained. Of the well-known shell-beds round the Selsey peninsula, those nearest to Selsey Bill correspond with (0) and (d). The beds at The Park and Thorney, on the east and west of Selsey, correspond with (g), and those of Bracklesham itself with (A). Of the fossiliferous beds near Stubbington, that of Brown Down corresponds with (d), and that at Hill Head with (f). Fine collections of fossils, in excellent condition, have also been obtained from the neighbourhood of Brook in the New Forest, from the horizons of (4) and(d). The large collections obtained from these localities by the late Mr, F. I. Edwards are in the British Museum, and those by the Rev. Osmond Fisher are deposited in the Woodwardian Museum, Cambridge. More recently (in 1886) clear exposures have enabled Mr. Keeping to fix exactly the junction of the Bracklesham Beds and the Barton Clay.* From the Sandstone or Tellina bed (No. XVI. of Mr. Fisher’s section) to the Nummutites elegans zone the distance is 126 feet. This is about 70 feet less than the distance given by Mr. Fisher and would reduce the total to about 580 feet. About the same time the measurements given below were made by the Geological Survey of the beds associated with the coal- seam (corresponding with No, VIL, VIIL, and parts of VI. and IX. of Mr. Fisher). Section in Whitecliff Bay, measured December 1886, Fr. In, Brown loam, not well seen. Black band of powdery lignite and sand - - - 02 Laminated beds of loam, sand, and lignite - - en (23-6 Shaly clay, full of slickensides, no fossils observed ~ a 93°:0 Worked out [coal, &c.] - ie ct - 7 6 Shaly underclay, with roots half an inch thick at the top and dying out below. Some of the roots are casts in clay, some in pyrites; nearly all have a film of lignite onthe outside - - - - - - 7 Similar clay with pyritous nodules, no roots observed - 8 0 * Geol, Mag., dec. III., vol. iv. p. 70. E 56786. H 114 GEOLOGY OF THE ISLK OF WIGHT. Fr. In. Hidden by talus = z = 24 0 Glauconitic ioam with yellow joints and much selenite. Casts of small oysters and other marine shells, and oceasional pieces of lignite - 5 0 Blue loamy clay with selenite and badly preserved fossils. Turritella imbricataria, fish-scales, &c. - - - 16 6 Clayey loam full of smail quartz and flint-pebbles, and crowded with fossils, mostly small. Ostrea, Cardita, Arca, Solen, &c. 7 0 6 Hard loam and clay, full of small fossils Sas Oael - 9 6 Clay with beds of Cardita planicosta and Turritella imbricataria 2 0 Laminated loam, clay, and sand, full of lignite. The Beds are perfectly vertical. ‘The above being distances measured along the beach, an allowance must be nade for the cliff not cutting the beds at right angles. The true thickness of the measured beds will therefore be 90 feet, instead of 113 feet. One or two sections where what is perhaps the base of the Bracklesham Beds is exposed have been mentioned in the last chapter, but the only locality yielding fossils is the cutting leading to Ashey Chalk-pit, about three miles south-south-west of Ryde. Here we find, above the London Clay, beds which are full of Bracklesham fossils. It is evident that unless the Bracklesham fauna here extends to the base of the Lower Bagshot Beds and into the London Clay we can only account for the proximity of the Bracklesham Beds to the Reading Beds by a strike fault, which baz cut out the greater part of the London Clay, all the Lower Bavshot Beds, and perhaps part of the Bracklesham Beds also. ‘Lhe section is not perfectly clear, but no fault could be detected, and there being no marked line of division between the two formations it is uncertain how much belongs to the one and how much to the other. Probably if there is really a fault its position will be at the point marked in the subjoined section. Untortunately the cutting being shallow at its northern ead and a good deal ovcerzrown, it was impossible to obtain details of the higher strat. All are nearly vertical. This disturbance will be again referred to in Chapter XIV. The highest bed which can be traced is a coal or lignite seam, formerly exposed in an old sand pit close to the line. The pit is now overgrown, but the coal was proved by boring. There follow 262 feet of alternations of laminated clay, loam, sand and seams of white clay. These strata cannot be examined, only the lower portion being seen in the northern end of the cutting, which ismuch overgrown. Then follow the beds with Bracklesham fossils as below :—~ Section in the railway cutting south of Ashey. Light-blue or greenish loamy sand, crowded Bracklesham with Bracklesham fossils ([V. of Fisher P) - Beds, Dark blue loamy clay with a little lignite 3 Blackish shaly clay with a little lignite 1g Dan 222 s Probable position of a strike-fault. BRACKLESUAM BEDS. 115 London Clay { Clay overgrown - - - ll 0 : Sand (Basement Bed of the London Clay) - 6 0 Reading Beds Red and mottled clay - 92.0 Chalk, nearly vertical. In the shelly bed 160 feet from the Chalk the following species (determined by Messrs. Sharman and Newton) were obtained, mostly by J. Rhodes (the fossil-collector of the Geological Survey). B_ Arca biangula, Lam. B_ Natica acuta, Sow. LB Cardita planicosta, Lam. B obovata, Sow. LB Corbula striata, Lam. B_ Pleurotoma dentata, Lam. B_ Cytherea lucida, Lam. LB denticula, Bast. LB — suberycinoides, Desh. = L teretrium? Edw. B —. trigonula, Desh. B_ Pseudoliva obtusa, Sow. B_ Rostellaria rimosa, Sow. B. Ancillaria buccinoides, Lam. Solarium, sp. B_ Conus deperditus, Brong. LB Turritella imbricataria, Lam. B_ Fusus longevus, Lam. B sulcata, Lam. LB pyrus, Brander. Voluta, sp. (fragment). Myliobatis (fragment). The species marked B (including the whole of the forms determined, with one doubtful exception) are well-known Brackle- sham shells; those marked L are found in the London Clay. The Plenrotoma teretrium (a somewhat doubtful determination) is the only species elsewhere confined to the London Clay. Between Ashey and Alum Bay no good sections of the Brackles- ham Beds occur. When the strata are again met with, in Alum Bay, their character is so entirely altered that it becomes impossible to correlate the minor divisions, or, as already stated, to be certain whether the upper and lower boundaries have been taken in the same place at opposite ends of the Island. In the following section the upper limit of the Bracklesham Beds has been taken at the point fixed, on paleontological grounds, by Mr. Fisher, instead of at the pebble bed originally adopted as the junction in the first edition of this Memoir. This increases the thickness of the Bracklesham Beds at this point by 44 feet, making the total 155 feet instead of 111 feet. The details of the fossiliferous beds above the conglomerate are taken from Mr. Fisher’s paper,* those of the lower beds are from the first edition of this Memoir. Section of the Bracklesham Beds in Alum Bay. Fr. In. Barton Cuay.—Dark sandy clay with fossils (principally small bivalves). Dark sandy clay - - - - - 15 6 Indurated, dark-greenish, sandy clay, with impressions of fossils - - - - 1 0 Fusus undosus P Cytherea lucida. Murex asper. suberycinoides. Pyrula nexilis. Sanguinolaria Hollowaysi. Turritella imbricataria. Modiola, sp. Natica ambulacrum. Tellina plagia. * Quart, Journ. Geol. Soc., vol. xviii. p. 85. (1862.) 116 GEOLOGY OF THE ISLE OF WIGHT. Fr, In. Dentalium, sp. Tellina filosa ? Cardium parile. - Branderi ? Cardita. sp. - sp. Arca aviculina. Dark sandy clay, containing a bed of septaria ll 0 Indurated, greyish, sandy clay, with impressions of fossils 0 7 Fusus undosus ? Cardita, 2 sp. Voluta nodosa. Cytherea obliqua. Natica, sp. ——-—-~ suberycinoides. Phorus agglutinans. -— lucida. Twrritella sulcifera. Tellina tumescens Dentalium, sp. —, 2 sp. Teredo, sp. Sanguinolaria Hollowaysii. Pecten corneus. Panopea corrugata. Cardium parile. Leda, sp. —- sp. Modiola (or Mytilus) sp. Dark sandy clay, weathering greenish grey, containing bands of lignite* = 16 0 Conglomerate of flint-pebbles, cemented by iron-oxide. The pebbles are of various sizes, up to a foot in diameter - = 1 te] © Sands (principally white), light tawny-yellow :n the upper part; the lower 3 feet crimson - - 45 0 Whitish marly clay - - - - - 25 0 Dark chocolate-coloured marls and carbonaceous clay, ) with much lignite and selenite. Fr. In. Clays and marls - - - - 15 8 Lignite band - - in) Clays and marls - - - - 3.03 29 6 Lignite band - - - bi 3 i Clays and marls - - - - 6 0 Lignite band - - 2 3 Clays and marls - - - - 4.3 Lignite band =~ - - Jin. tol 0; Clays and marls - - - - BOs) Total thickness of the Bracklesham Beds 155 0 Whether the lower part of this section really belongs to the Bracklesham Beds is doubtful. Mr. Fisher takes as the base of the Bracklesham Beds at Alum Bay the bed of flint pebbles formerly adopted by the Survey as the hase of the Barton Clay. He therefore places the pebble beds at Whitecliff and Alum Bays approximately on the same horizon. The pebble bed at Alum Bay certainly appears to mark the incoming of marine conditions, after the deposition of the plant-bearing sands and pipe-clays of the Lower Bagshot Beds. Butin the absence of recognizable fossils throughout the whole of the next 500 feet of strata, it is possible that we are merely dealing with decalcified equivalents of the marine beds of Whitecliff Bay and Bracklesham. The pebble bed at Alum Bay may therefore really belong to the * This is the lowest bed attributed to the Bracklesham Series in My, Fisher’s section. BRACKLESHAM BEDS. 117 middle or upper part of the Bracklesham Series, since pebbles occur on various horizons at Bracklesham itself. Though the Bracklesham Beds of the Isle of Wight have only yielded 2 small portion of the prolific fauna found at Selsey, yeta considerable number of the most characteristic Bracklesham species oecur in both districts. Among the most conspicuous may be mentioned Mwmmulites levigatus, Turritella imbricataria (Fig. 23), and Ourdita planicosta (Fig, 22). Fia. 22. Fig. 28 Cardita planicosta, Lam. Turritella imbricataria, Lam. Specimens of the Curdita obtained from the lower portion of the beds at Whiteclitf Bay are not only much less in aize than those found at Bracklesham, but are pierced by small boring shells; showing that the animals must have perished, and the shells have remained a considerable time at the bottom of the sea before they were covered by the sediment in which they are now eee of the Bracklesham Beds of the Isle of Wight appears to show a sub-tropical climate, shoal-water, the eae of land, and perhaps estuarine conditions. The occurrence of a coal-seam, resting on an ancient vegetable soil, indicates an eleva- tion to a sufficient extent to raise the beds above the sea-level for a portion of the time. Barton Cuay. This group of strata which is displayed in the cliffs aut ean os the opposite coast of Hampshire, and is so well known to collee a for the richness and abundance of its fossils, is here ae sented by clays overlying the Bracklesham Beds = ee Whitecliff Bays. The nature of these deposits (w alo ae Coin posed of sandy clays, clays, and sands with layers of septaria) is 118 GEOLOGY OF THE 1SLE OF WIGHT. sufficiently shown in the measured sections of Alum Bay, in which locality they attain a thickness of about,250 feet. Section of the Barton Clay in Alum Bay.* (Measured in April 1851.) Fr. In. Ferruginous dark-blue clay, selenite, fragments of univalve shells, numerous fossils = - - 24 0 Pale and ferruginous yellow sandy clay, green in the upper part. Lignite, Corals, Dentalium, Ostrea, Corbula, Pleuro- toma commen and of several species. (The pathway from pe chine to the beach cuts through the lower part of these eds) - - - - - Sands, pale yellowish colour above, green below. (A layer of septaria occurs in this bed about 10 feet from the top, containing pebbles and fragments of wood, and overlying a band of small flint-pebbles) - - - 35 (0 Dark bluish-grey and ferruginous-brown sandy clay, con- taining much selenite and lignite. Corbu/a abundant. (A layer of septaria, 1 foot thick, occurs 5 feet from the top, 3 feet under which is a band about 2 inches thick of very small pebbles of white quartz, with Shark’s teeth. A second layer of septaria occurs at 28 feet; and a third, 5 feet from the bottom of the bed. There is also a band of fossils at 13 feet, and a band of lignite 10 feet from the 69 0 bottom) : - - - - - 53° 0 Pale grey loamy sand, mottled with yellow, and thinly laminated - - - - - 9 0 Dark bluish-green clay, with numerous univalves and other fossils. A ribbed Dentalium, Fusus longevus, Voluta spinosa, Solarium, Cardium, Natica (2 species), Fusus pyrus, Rostellaria, Cancellaria, Pleurotoma, Mitra (small species) - - - - 65 0 ‘Total - 255 0 The Rev. O. Fisher gives the following details of the base of the Barton Clay (including 15 feet of beds) at this point :+— Dark-greenish, coarse, sandy clay. Crowded with Nummulina Preste wichiana [now known as N. elegans]. Rostellaria ampla. Strepsidura turgida. ——- rimosa. Cassidaria ambigua. Murex asper. Ancillaria, sp. Typhis pungens. Pleurotoma turbida. Cancellaria, sp. conoides. Pyrula nexilis. ————— plebeia. Fusus bulbus. » Sp. carinella. Voluta athleta. —— errans. ——— depauperata. ——- interruptus. maga, —- longevus. ——— nodosa, —— Noe. — Mitra parva. —— regularis. Marginella, sp. ——- unicarinatus. Natica labellata. —— sp. Turritella imbricataria. * Another section, differing somewhat in details, will be found in Messrs. Gardner, Keeping, and Monckton’s paper. Quart. Journ. Geol. Soc., vol. xliv. p- 600. t Quart. Journ. Geol. Soc., vol. xviii. p. 84. (1862.) BARTON CLAY. Phorus agglutinans. Calyptreea obliqua. Dentalium, sp. Ostrea flabellula dorsata P Pecten corneus. Cardium, sp. Lead-coloured clay, with few fossils Rostellaria macroptera. 119 Corbula pisum. Pholadomya, sp. Echinoderm. Operculina, sp. Nummulina Prestwichiana, é 2 é 3.0 Corbula pisum. Dark sandy clay, with fossils (principally small bivalves) — - 9 0 Rostellaria ampla. Arca aviculina. Fusus regularis? Leda, sp. Pleurotoma exorta. Nucula, sp. Voluta nodosa. Cardium parile. Turritella imbricataria. Cardita globosa. Melania? Cultellus, sp. Calyptreea, sp. Corbula pisum. Solarium plicatum. These details of the lower beds are given to show how gradual is the upward passage, both lithological and palzeontological, from the Bracklesham Series, already described at p. 115, into the overlying Barton Clay. When the original survey of the Island was made an inland exposure of the Barton Clay was visible at Gunville. This is now overgrown, and no new sections are at present open. The Brick Yard at Gunville showed shelly clay, from which were obtained numerous sharks-teeth and some mollusca. Unfor- tunately few of these have been preserved, and the new Brick Yard on the west side of the road only shows Pleistocene Brick- earth, resting on the upturned edges of the Lower Bagshot Sands, with perhaps in one place a trace of the base of the Bracklesham Series in some green sandy clay. At the east end of the Island the Barton Clay is seldom well seen, owing to the accumulation of beach, and to the Jandslips and mud-streams which constantly obscure this part of the cliff. However in 1886 the sections were exceptionally clear and Mr. Keeping was able to examine this part of the coast and to measure the following section.* Section of the Barton Clay in Whitecliff Bay. (Measured by Mr. H. Keeping in 1886.) Fr. In. Blue sandy clays, with mottled brown patches of soft earthy ironstone near the base. The upper 15 feet consist of bluish sandy clay, containing - - - - 50 0 Terebellum sopitum, Brand. Voluta humerosa, Edw. Pyrula nexilis, Lam. Natica, sp. Calyptreea trochiformis, Lam. Ostrea flabellula, Lam. Pecten carinatus, Sow. > Sp. * See Geol. Mag., dec. III. vol. iv. p. 70. 120 GEOLOGY UF THE ISLE OF WIGHT. Fr, Iv. Lima, sp. Cypricardia, sp. Avicula media, Sow. Cardita oblonga, Sow. Arca, sp. Cytherea tenuistriata, Sow. Pectunculus deletus, Brand. Tellina ambigua? Sow. Limopsis scalaris, Sow. Corbula ficus? Brand. Nucula bisulcata, Sow. Panopwza intermedia, Sow. Chama squamosa, Brand. Cardium porulosum, Brand. Schizaster D’Urbani, Forbes. Lucina gibbosula, Lam. Crassatella tenuisulcata, Edw. Ditrupa plana, Sow. Imperfect ironstone band, not well seen - - - 3.0 Grey and pale blue clays, with light fawn-coloured bands near the base - - - : - - 36 0 Stiff laminated clay, with occasionally dark patches. Few or no fossils - - - - Ik 0 Pale blue and yellow sandy clays, with very few and badly preserved fossils = - - - - 54 0 Nummutlites elegans zone, consisting of rather dark green and blue glauconitic sandy clays, much crowded in places with Nummulites elegans. Fossils:— _ - - - - 11 Typhis pungens, Brand. Bulla, sp. Fusus bulbus, Brand. Cominella Solandri, Edw. Corbula pisum, Sow. Pleurotoma exorta, Brand. Crassatella sulcata, Brand. Voluta luctatrix, Brand. Cardium semigranulatum, Sow. ——— digitalina, Lam. Leda minima, Sow. Mitra parva, Sow. Ostrea flabellula, Lam. Calyptrea trochiformis, Lam. Dentalium striatum, Sow. Nummulites elegans, Sow. Total 162 1 The Barton Clay of the Isle of Wight yields a fauna closely corresponding to that of the typical locality on the opposite coast of Hampshire, but at present the list of fossils is much smaller. This is perhaps partly due to a greater poverty of the fauna, but in all probability it mainly arises from the difficulty in following thin fossiliferous seams where the beds are so much hidden by landslips. Another reason is that the area over which each seam can be examined is much less in the Isle of Wight than at Barton, owing to the tilting of the beds and their rapid disappearance beneath the sea-level. As in the Bracklesham Beds, the mollusca in the lower part of the Barton Clay of Alum Bay show a decidedly warm climate, but the fossils are more exclusively marine, the beds contain a smaller mixture of lignite, and show altogether less sign of the proximity of land. Among the more conspicuous fossils are Nummulites elegans, Pecten reconditus (Fig. 35), Corbula pisum, Crassatcllu sulcuta (Fig. 29), Peetunculus deletus, Psammobia compressa (Fig. 27), Calyptreu. trochiformis (Fig. 33), Conus dormitor (Fig. 32), Fusus longevus (Fig. 31), Fusus pyrus (Fig. 26), Murea usper (Fig. 25), Phorus agglutinins (Fig. 24), fiostellaria vimosa (Fig, 28), Lyphis pungens (Fig. 34), Voluta luctatrix (Fig. 30), &c. = BARTON CLAY. 1A Fia, 24. Fria, 25. Fia 26. Phorus agglutinans, Murex asper, Fusus pyrus, Desh. Brand. Lam. Fig. 28. Fria. 29. Rostellaria rimosa, Sow, Crassatella sulcata, Sow. Fic 30 Voluta luctatrix, Sow. , Fia. 32. Conus dormitor, Sow. 122, GEOLOGY OF THE ISLE OF WIGHT. Fra. 33. Fie. 34. Fria. 35. Calyptrea trochiformis, Typhis pungens, Pecten reconditus, Lam. Brand. Brand. i OW e> Herapon Hitt Sanps. Between the Barton Clay and the Headon Beds lies a mass of unfossiliferous or sparingly fossiliferous sands. These have been usually called Upper Bagshot Beds, but as they probably belong, as already mentioned, to a higher zone than the Upper Bagshot Series of the London basin, it is better to use for the present the older term “ Headon Hill Sands.” The lower part of these strata at Headon Hill consists of about 50 feet of yellow and white sand, succeeded by 60 feet of white sand, with occasional yellow stains caused by the presence of oxide of iron, The total thickness of this group in Alum Bay cannot be determined accurately, in consequence of the disturbed state of the beds there, but probably it ranges from 140 to 200 feet. The Headon Hill Sands are of considerable economic value, their whiteness and purity rendering them particularly suitable for making: glass, for which purpose they were extensively worked for many years. Mr. Squire, who rented the cliffs for several years, stated that between 1850 and 1855, 21,984 tons were shipped from Yarmouth, principally to Bristol and London, for the use of the glass-houses there; and a native author, writing im 1795, says,—‘Our trade and commerce chiefly is dealing in corn and wool. There are other commodities, such as copperas stones and white shining sand. The former are gathered up in heaps on the sea-shore, and occasionally sent to London, &e. for the purpose of producing the several species of vitriol ; the latter is dug out of some very valuable mines, which are the property of David Urry, Esq., near Yarmouth, and from thence sent to London and Bristol for the use of the glass manufactories.” , Inland there are at present few or no clear sections of these Sands, but pits, now overgrown, formerly showed the junction with the overlying clays of the Fluvio-marine beds. This junction was formerly seen in a pit about half a mile west of Swainstone, by the vide of a road to Fulholding Farm; and, again, further east, under similar circumstances, in the lane a short distance south of Great Park Farm. HEADON HILL SANDS. 123 South of Gunville about half a mile from Carisbrook in a north- west direction, the Headon Hill Sands and the Barton Clay are thrown up into a vertical position in the brick-pits, where the latter deposit constitutes the brick-earth which was formerly worked there, and, as has been already stated, contained a few fossils, In East Medina, the Headon Hill Sands showed themselves near Mornhill Farm, and in a pit at the south-east corner of the wood by the side of the road from Arreton Down to Lynn Farm, where they are pure white glass-house sands, together with some of a yellow colour. They are here also vertical, resting with a sharp, well-defined line (marked by a few small rounded flint- pebbles) on green clay—Barton Clay. The age of the strata in this last section is, however, somewhat doubtful, for they are curiously disturbed at this point, and so hidden by gravel that the sands may possibly belong even to the middle division of the Hamstead Beds. Unfortunately this pit being now entirely overgrown cannot be re-examined. The Headon Hill sands have also been observed in pits at Combley and south of Little Nunwell, as wel] as on the north side of Bembridge Down, by the side of the road to Bembridge Farm. In Whitecliff Bay the junction between the Headon Hill Sands and the Barton Clay is likewise sharp and well defined, and the former group has a thickness of 154 feet. Fossil remains are particularly scarce in this member of the Eocene series; though repeatedly searched for during the pro- gvess of the survey, no fossils were procured except in Whitecliff Bay, where a few ferruginous casts of bivalve shells were found— chiefly Tellina, Panopea, &¢—which, however, could not be preserved on account of their loose and friable condition. 124 GEOLOGY OF THE ISLE oF WIGHT. CHAPTER X. OLIGOCENE. INTRODUCTION. THE Fluvio-marine or Oligocene Beds of the Isle of Wight were first described by Webster, who divided them into Lower Freshwater, Upper Marine, and Upper Freshwater, but treated as extensions of the beds in Headon Hill a large series of fluvio- marine beds really lying above the Upper Freshwater.* It was not till the year 1853 that the complete succession was satisfac- torily made out, though Prof. Prestwich had already, in 1846,f suggested that the beds seen in Hamstead Cliff were higher than any of the beds at Headon. In 1853 Edward Forbes showed that above Webster’s “Upper Freshwater” of Headon Hill, there is found a thick series of beds divisible into several zones characterised by distinct species of fossils. A few years later, in 1856, the observations on which Forbes had been engaged up to the date of his death were published in the Memoirs of the Geological Survey, but the incomplete state in which many of the notes were left rendered it very difficult for Mr. Godwin-Austen, who edited the book, to do full justice to Forbes’ work. The divisions and mea- surements made by Forbes have been adopted with very little alteratiun in the present Memoir. Later observers have some- times grouped the beds differently ; but this grouping is so much a mat‘ r of opinion, and. there is such an entire absence of real breaks, tha: antil stronver evidence is brought torward it seems unnecessary to depart from the classification and nomenclature adopted by Edward Forbes. The following brief summary of the views taken by some of the able geologists who have written on the geology of the strata under notice, may not be out of place here. Professor Thomas Webster gave the earliest and perhaps the best account of the Fluvio-marinc series, founded on observa- tions made in the years 1811-153, and contained in Sir Tlenry Englefield’s work on the Isle of Wight,$ published in 1816. In those letters Professor Webster divided the section at Alum Bay into Lower Freshwater, Upper Marine, and Upper Freshwater * Sir H. C. Inglefield. A description of the Principal Picturesque Beauties, Antiquities, and Geological Phenomena of the Isle of Wight. With Additional Observations on the Strata of the Island, &e. by Thos. Webster. (London, 1816), pr226. . { On the Occurrence of Cypvis in a part of the Tertiary Freshwater Strata of the Isle of Wight. Rep. Brit, Assoc. for 1846, Trans. of Sections, p. 56. £ Quart, Journ. Geol. Soc., vol. ix. p. 259. S$ The letters of Professor Webster are illustrated by large copperplate views of clifts and coast scenery which, for accuracy and spirited execution, have perhaps never been surpassed as drawings illustrating geological phenomena. OLIGOCKENE—INTRODUCTION, 125 Formations; and Headon Hill was considered to comprise a com- plete section of the whole of the Flivio-marine series, Although the calcareous strata in the upper part of Headon Hill were noticed, the limestones of other parts of the Island were referred to some of the thick beds of Lower Headon limestone displayed at Headon Hill, and all the marine shells of the Fluvio-marine series to his “ Upper Marine” formation, or the Middle Headon beds of Professor Forbes. Hence the limestones of Gurnard Bay, East and West Cowcs, and Binstead were referred to the “ Lower Freshwater” formations, while the “ blocks of calcareous stone containing Limnea lying on the top, in a detritus of blue clay,” seen along the shore eastward of the latter locality, as also the limestones of Dodpits and Bembridge, were considered iden- tical with those of the “ Upper Freshwater” formation, or the thick limestones which are displayed in the Upper Headon beds at Headon Hill. Mr. G. B. Sowerby visited Headon Hill in 1821 and inferred that the Upper Marine formation had been deposited under estuarine rather than under marine conditions, in consequence of observing the occurrence together of shells of marine and fresh- water genera.* Professor Sedgwick, in a paper published in May 1822,+ referred all the strata exposed in the cliffs between Bembridge Ledge and Ryde, between Ryde and Gurnard Bay, and also the argillaceous beds between Yarmouth and Hamstead, to the Lower Freshwater formation of Professor Webster; while the oyster bed and marine marls overlying the Bembridge Limestone, and the upper argillaceous beds of Hamstead, were regarded as the equivalents of the Upper Marine formation of that author. Professor Prestwich showed,{ in 1846, that there were no grounds for the supposition of a want of conformity between the series in Alum Bay and that in Headon Hill, and expressed an opinion that no well-marked divisions could be drawn there, as proposed by Webster,§ inasmuch as marine shells of the Barton clays re-appear among the overlying freshwater strata in White- cliff Bay, and that the same freshwater species ranged through nearly the whole thickness of the Headon Hill deposits; the phenomena being such as might be purely local, the result of an accidental irruption of brackish water into a freshwater area. With respect to the age of the fluvio-marine series of the Isle of Wight, and their synchronism with the deposits of the Paris basin, Mr. Prestwich stated that he felt considerable hesitation in hazarding an opinion ; but, guided by the circumstance that all Trench and English geologists were agreed in referring the Barton group to the Calcaire grossier, as also by the consideration of the upward range of the Barton species, he was disposed to * Qn the Geological Formations of Headon Hill. . . . Ann. Phil., ser. 2 vol. ii. p. 216. ; ; : + On the Geology of the Isle of Wight. Ann. Phil., vol. xix. p. 829. £ Quart. Journ. Geol. Soc., vol. ii. pp. 223-259. § Lower freshwater Upper marine, Upper freshwater. 126 GEOLOGY OF THE ISLE OF WIGHT. consider the Headon Hill series as the upper portion of the Barton group, and, as such, to refer the whole to the Calcaire grossier. In the autumn of 1846 Prof. Prestwich communicated a paper “On the occurrence of Cypris ina part of the Tertiary Strata of the Isle of Wight,”* to the Geological Section at the Meeting of the British Association at Southampton. The place from which these fossil Cypride were obtained was the upper part of Hamstead Ciift, near Yarmouth. The author gives a section of the beds, which will be found to agree most accurately with the description contained in the subsequent por- tion of this Memoir, and notes the genera of the included shells, adding “ We have thus in the lower part of the section a deposit containing essentially freshwater testacea, becoming more mixed, as we ascend, with shells frequenting estuaries. It is a singular feature of this group, which I believe to form the upper beds of the freshwater formation of the Isle of Wight, that a large portion of the species occurring in it are new; thus the two characteristic fossils are a species of Potamides and a Melunia, neither of which do I find described. The Cypris also is peculiar to this locality.” From the passages here quoted it will be seen that Professor Prestwich had the clue to the structure of the Upper Tertiary series of the Isle of Wight, and that time and opportunity were alone wanting to enable him to work out details on which the Bembridge and Hamstead groups were shortly afterwards shown by Forbes to be clearly separable from the Headon series, with which they had continued to be confounded. In 1853 Forbes published} an outline of the results of his work in the Isle of Wight between the years 1848 and 1853. In this paper he gave a new reading of the succession, and a revised classification and nomenclature of the beds. This was followed in 1856 by his posthumous memoir “On the Tertiary Fluvio- marine Formation of the Isle of Wight,”{ and in 1862 by the first edition of the present Memoir. The only subsequent criticism tending in any way to contra- dict the work of Forbes was contained in a paper by Prof. Judd.§ This author maintained the correlation of the Headon Beds at Headon Hill with those of Totland and Colwell Bays to be erroneous and stated that “the strata exposed at the base of Headon Hill are not, as supposed by previous observers, a mere repetition, through an anticlinal fold, of the beds seen in Colwell and Totland Bays, but are on a distinct and lower horizon than the latter. ‘hese Headon-Hill beds are also found to contain a different assemblage of fossils from that which characterizes the Colwell and Totland Bay beds.” Prof. Judd also proposed a new classification of the Oligocene Beds, in which they were divided * Report Brit. Assoc. for 1846, p. 56 (Cundona Forbesti, T. R. J. in Prof. Prest- wich’s Collection). t Quart. Journ. Geol. Soc., vol. ix. p. 259. t Memoirs of the Geological Survey. § Quart. Journ. Geol, Sov., vol. xxxvi. p. 187. (1880.) OLIGOCENE—INTRODUCTION, 127 into Headon Group (estuarine), Brockenhurst Series (marine), and Bembridge Group (cstuarine). Subsequently Messrs. Keeping and Tawney maintained that the correlation of the marine beds of Fleadon Hill and Colwell Bay made by Forbes and the Survey was correct, and that the faunas at the two spots were practically identical, the slight variations being accounted for by the somewhat different conditions under which the beds were deposited.* Forbes’ correlation is followed in this Memoir, for though there are some minor points on which Prof. Judd’s criticisms are-no doubt just, yet with regard to the main difference the recent re- examinition of the Island and mapping of the beds on the scale of 6 inches to the mile have not supported Prof. Judd’s contention, but rather shown that Forbes’ correlation must still be accepted. As already observed, the subdivision and grouping of the beds in such a variable series of strata are, in the absence of any real breaks, so entirely a matter of convenience, that without stronger evidence it would be most unadvisable to upset the established nomenclature, and introduce a new mode of grouping, founded on that adopted in other districts. Here also the original nomencla- ture and grouping used by Forbes have been adopted. The principal alteration in this new edition of the Memoir is in the use of the term Oligocene for the whole of the Fluvio- marine beds formerly known partly as Upper Eocene and partly as Middle Eocene.t This term is universally adopted on the continent, and the change of conditions at the base of the Pluvio- marine series is so marked in the Isle of Wight, that the division of our Lower Tertiary Beds into two, instead of into three series, and the acceptation of the Headon Beds as the base of the upper group is very convenient. Of course the rarity of fossils in the underlying Headon Hill Sands leaves it still somewhat uncertain to which group they should belong, but the marked change of lithological character at the base of the overlying beds, and the fact, recorded by Forbes, that the Sands contain marine fossils uf Barton species, is certainly in favour of their being grouped with the Barton Clay. Tape of the OrigocENE Bens of the IsLE or WiGHT. FEET. Hamstead Series about 260 Bembridge Marls - » 100 ee Limestone » 10 Osborne Series - 4, 100 Upper Headon Series - Middle Headon Series (marine) —- = 5, 150 Lower Headon Series - - - Total - - - 620 * Quart. Journ. Geol, Soc., vol. xxxvii. p. 85. (1881.) + Lyell referred the highest portion to the Miocene. 128 GEOLOGY OF THE ISLE OF WIGHT. Owing to the high dip and absence of any topographical feature, it has been found impossible to separate the Osborne from the IIecadon Series on the Map. These two series are therefore shown by a single colour, though described separately in this Memoir. Heapon Beps. This serics, as a whole, consists of a mass of beds of fresh- water, estuarine, and marine origin, the total thickness of which varies from 147 feet at Headon Hill to 212 feet at Whitecliff Bay. It is only at the western extremity of the Island, between the river Yar and the sea, that the Headon series covers an extensive area, elsewhere it is comprised in a narrow belt of land, between the Headon Hill Sands and the Osborne Series. These beds are best displayed at Headon Hill, in Totland and Colwell Bays, and in Whitecliff Bay. There is also a small section of the upper portion—now almost entirely overgrown or hidded by the sea-wall—on the coast close to Norris Castle and Osborne. The Fluvio-marine formation, which extends over the northern portion of the Island, forms an undulating tract of country, the scenery of which presents a marked difference to that of the more open district covered by the Cretaceous rocks on the south, owing to the greater abundance of woods with which the surface is in many places covered. The land situated on the limestones is of a more fertile description than that based upon the clays or sands, but over a considerable part of the Island mapped as Fluvio-marine there is a thick deposit of flint gravel spread over the surface, which conceals the underlying strata, and causes the agricultural nature of the soil to bear no relation whatever to the rocks beneath. From the highly inclined position of the beds in the neighbourhood of the Chalk, the lower members of the formation are comprised, for the most part, within comparatively narrow limits, and the chief’ portion of the superficial area occupied by the Iluvio-marine series consists of the upper members of that group. The thick beds of limestone in this formation thin out towards the north, and nearly disappear in an easterly direction. The Headon Series was subdivided by Edward Forbes into :— Uppermost marls, with Cerithiwm lapidum ? Upper Headon freshwater and brackish beds. 2. Middle ; Headon intermarine. 3. Lower Headon fresh and brackish-water beds. 1. Upper { The following sections, measured during the original survey of the Istand, will give a good idea of the nature and fossils of these beds. It must not be forgotten, however, that cach of the minor divisions is extremely variable, and many of them are found to die out or entirely change their character in short. listances. IEADON BEDs. 129 Section of the Headon Scrics of Headon Hill, measured by Edward Forbes in October 1852 (with w few Corrections mude in 1888.) a ( Blue and yellow clays and marls, passing into grey laminated clays with crushed Paludina lenta and Potamomya gre- garia - - 15 0 Variegated clays with Potamomya, espe- cially in the lower part. A 6-inch band of ironstone with Paludina occurs in the centre of the bed. Serpula - 3 3 Brown and green clays. Potamomya, Paludina lenta, Melanopsis fusiformis- 3 4 Limestone, carbonaceous at the top ; details :— Carbonaceous - - 1 0 Sandy, with crushed Linnea longiseata and Planorbis Upper Headon euomphalus - 2 0 _ Beds, < Full of fine shells; Limnea Ab ft. 7 ins. longiscata, Planorbis euom- > 8 0 phalus, P. lens, P. obtusus, P. rotundatus, P. platy- stomus, Paludina, &c. - 2.0 Rubbly, with Planorbis ewom- phalus - - - 3 0 Bluish and purplish clays, passing into Limestone. Melanopsis —_carinata, Limnea longiscata, Planurbis platy- stoma, P. obtusus, Bulimus politus - Limestone, compact in places, with many shells and lines of nedular concretions in places. Shells as in the limestone above - - - - 10 0 Greenish-white compact sands, carbo- naceous at the base. Serpula tenuis - 2 0 Blue clays and sands, crowded with univalve shells. Cerithinm ventri- cosum, C. concavum, C. pseudo-cinctum, Cyrena obovata, Ostrea, Natica. The shells are much broken at the lower part (at 2 feet down) and larger than further northward = - - - Yellow sand, with bands of lignite and clay. Cerithium concavum - - Blue-green clay with lignite. Fossils few :—Cyrena obovata, scattered Ostrea 2 Limestone. — Planorlis euomphalus, Limnea longiscata = - - i Blue, green, and brown sandy clay, with oyster-beds at about 5 feet Middle Headon from the top. A few fossils in Beds, blue clay above ; fossils mostly in 33) ft. the middle and lower part. Occa- sional flint pebbles. Ostrea, Cyrena obovata, Cytherea incras- sata, Nucula, Natica depressa, Melania, Fusus, small species. The oysters in this bed are smaller and fewer than at Colwell Bay ; the other marine shells are also fewer - - - - 16 0 E 56786. T Ci Qo to o cS 2 ww VENUS BED, ese NS ee - 130 GEOLOGY OF THE ISLE OF WIGHT. Fr. In. (Sand, clay, and lignite; with bands full of bivalves and scat- tered _univalves. Cyrena obovata, Cerithium ventricosum, C. concavum, C. pseudo-cinctum, Neritina concava, Melanopsis L. fusiformis - 1 0 Cream-coloured limestone in one bed. Limneea longiscata, Planorbis euom- | phalus, P. lens? This corresponds with the limestone of How Ledge 3.0 Sand, clay, and lignite, with seeds. At the bottom 2 feet 9 inches of strong | carbonaceous bands with seeds and univalves. Carpolithes, Melania - 20 0 Limestone with shells (much broken) | probably brackish water? Limnea NERITANA BED aa longiscata, Nematura - 1 6 Green clays ; fossils few or none 8 0 " - 2 0 | Ferruginous bands, alternating with | clays full of Paludina - 3 0 Pale sands with bands of lignite - 428 CyrENA PULCHRA Bep.—Green clays, carbonaceous at the base. Cyrena pulchra, Potamomya, Limnea 0 6 Limestone, very shelly in the middle, | and divided into two beds by a clayey parting. Limnea longiscata, L. cau- data, Planorbis euomphalus, Hoa Lower Headon of Paludina - 5 4 Green clays with parish sheeiles (from this clay to the base of the Headon Series the beds vary very much at different places) - 14 Sandy limestone, very shelly and ferru- ginous at the base. Shells crushed 0 6 White and yellow sand, with a car- bonaceous band ut the top 0 4 *Blue clay with shells; becomes sandy below. Potamomya, Cerithium - 46 Sandy limestone, passing upwards into sand. Plunorbis ewomphalus, Limnea longiscata (shells much broken) Strong band of ironstone 2 inches to 0 CyRENA CYCLADIFORMIS Brp.—Sandy green clays, Potamomya, Cyrenu cycladiformis, Cerithium i ta C. duplex - - 3 0 White sands with harder bands - - - 1 6 Green clays with a thin ferruginous band 1 inch thick at the base. No fossils? - 6 0 L Total - 146 10 ; Bright yellow sands, with white sand, Headon Hill Sands forming lenticular patches in yellow sand - - - - ll 0 as, Se Another Section measured downwards from the beds marked (*), nearer Alum Bay, is slightly different. Lower Headon Beds. HEADON BEDs. (Green clays with thick bands of Pota- | momya plana. Paludina in places. Selenite - - - | White sands, without fossils — - : Thin band of sandy limestone with | Planorbis, &e. - - White clayey band. No fossils White sand - . Green marls with lignite bands. Broken Cyrena and Potamomya, Cerithium elegans? C. duplex? - - Pink and yellow rather compact sands, with a lignite band at the top - Ferruginous ledge of dark-red sandy beds, with a strong but narrow iron- band at the base. No fossils - - | White sands (Headon Hill Sands). Fr. mete 131 In. 6 0 The Headon Beds vary so much in short distances that other measurements, made only a mile or two from Headon Hill give very different results, though the total thickness is nearly the same. The following were taken about 1852 by E. Forbes and H. W. Bristow Section of the Headon Beds in Colwell and Totland Bays. Fr. In. Upper Headon Beds, 475 feet. va Dark blue clays alternating with ferruginous and septarian bands. Paludina lenta, P. globuloides, Limnea longiscata, Serpula, Potamomya gregaria - Red and green marls - Sandy beds, greenish clays, and grey shales, with lenticular patches of broken shells and wood. Puludina lenta above, Potamomya? Cyrena obonata, var. major, fragments of Unio, Melanopsis fusiformis P and Melania muricata - - - - White, yellowish, and dark sand, with clayey streaks. MWelanopsis fusiformis, M. subcari- nata? Cyrena pulchra. Lenticular patches of dead Melanopsis and Cyrena obovata in the lower part - - Limestone. Limnea longiscata, Planorbis - Greenish clay and sand, crowded in places 2 with univalve and bivalve shells. A ferru- ginous band at 10 inches from the bottom of the bed. Potamides trizonatum, Cyrena obovata- - - - - Argillaceous limestone, passing southward into a bed of sand. A carbonaceous band occurs at the base. Paludina angulosa, Limnea longiscata, L. subquadrata?, Is. angusta?, L. arenularia?, L. tenuis ?, Planorbis euomphalus, P. rotundatus, P. obtusus, P.. lens, P. platystoma, Nematura. (This bed occupies the foreshore at Cliff End Fort) - - - : Bluish-yellow and purplish laminated sands and carbonaceous shales (under the battery, southern end) - - Laminated clay and sand, with ferruginous sandy lenticular patches and lines of Pota- momya in places. Potamomya - a 10 3 10 te 132 GEOLOGY OF THE ISLE OF WIGHT. Middle Headon Beds, 30 feet 4 inches. (Rather compact pale greenish-yellow sand, without fossils - ae, oF Verdigris-green clayey beds, abounding in Cyrena obovata, Ostrea, Melania muri- cata, Cerithium concavum, Natica - - Band of ferruginous concretions, often cal- careous internally. Small Nematura or Hydrobia, Neritina (rave), Cerithium pseudo-cinctuim, Meiunia muricata, Cyrena obovata, Modiola, Ostrea (rare) 3 inches to Bluish-green clays, often very fossiliferous. Cyrena at the top of the bed, and Ostrea in lenticular patches in the lower part, which becomes blacker and contains cal- careous nodules. Cyrena obovata, Mytilus affinis, Cerithium pseudo-cinctum, Neritine 3 feet to Lignite and clay; sand in places. Nume- yous bands of Potamomya near the base. Cerithium pseudo-cinctum, Neritina, Mela- é nopsis - . “Venus Bep.” Brownish clay full of ' marine shells. Bank of oysters varying in thickness in different places. Ostrea velata, Cytherea inerassata, Corbula | cuspidata, Cerithium pseudo-cinctum, Fusus, Murex, Voluta spinosa, Cancellaria, 2 sp., Pleurotoma, 2 sp.,Nucula headonensis, Arca, Natica, 3 sp., Bulla, 2 sp., Tellina, 2 sp. (The Oyster Bed rises a little (15 feet) south of Linstone Chine) - - - Very variable alternations of blue and red clays and yellow and white sands, becoming fossiliferous, especially near the base, and with a ferruginous band 43 inches thick in the centre. Ostrea, Alelania muricata, Cerithium pseudo-cinctum, &c. . - “Neritina Bep.’ Dark-blue sandy clay. with two well-marked bands of Cyrena. Cyrena obovata, Cerithium, 3 sp., Neritina concava, Melauopsis fusiformis, Nematura, Chara - - . ( Whitish sandy clay with crushed Linnea - Limestone. Linnea longiscata, L. pyrani- dalis, L. gibbosula, L. minima, Plinorbis enomphalus, P. rotundatus, P. obtusus ?, P. platystoma, P. lens, Puludina (rare), Chara. (This limestone forms How Ledge) - Whitish and grey calcareous clay, passing into Limestone with thick bands of crushed Linnea and lignite near the top and scat- tered Prludiua beluw. ‘Vurtle bones Blue soft sandy clay, witb bands of Paludina, small black seeds, and Uuio Solandri - Purplish-grey carbonaceous lamine with oblique root like markings. Bands of Paludina, Melania, Cyrenu, Unio, Seeds - Brown, red, and grey clays and sands, with seams of Paludina. Paler sands below - Sand, abounding with small shells above, and with a concretionary band at the base. Helix labyrinthica, Achutinu costellata, Limnea pyramidalis, L. caudata, Le. Fr. In 2) 3.0 1 0 5 2 0 9 0 6 0 Bog 2 3 oo: a) 410 4 0 0 x8 8 0 HEADON BEDS. 133 longiscata, Li. mixta ?, Ih. fusiformis, Li. Fr. ty. tumida ?, Planorbis rotundutus, P. lens, P. obtusus, ‘Melanopsis brevis, Melania, Palu- dina lenta, Cyrena eycludiformis?, C obovata, Chara 2 6 Bed partly concretionary, pankle sandy ith lenticular masses of broken SO (Forms Warden Ledge) - 3.6 Lower Headon | Pure white sand with bright gellow stripes. Beds, 82 feet ~ No fossils - 8 0 4 inches. ae grey sandswith bands of Potamomy aa Seeds - - *Carbonaccous sand and clay, with bands of Potamomya, A strong band of lignite at the base. Seeds. Puludina scarce - 6 Pale-green sandy clays - Limestone, with Potamomya at the top. Planorbis euomphalus, Limnea longiscata, DL. pyramdalis, L. suleata - - - 16 Greenish and yellowish clay with lignite 2 6 to Imperfect Limnzean limestone - - Pale-green marls, with roots in places and occasional broken Limnea and Paludina. sMelanopsis. (Numerous bands of Pota- momya near the base) - - - 14 0 Imperfect Limnzan limestone ; very soft, with crushed shells - 10 0 a = t ts an Ow an te White and yellowish sand, N oO fossils Hard greenish marl. Me/anopsis brevis, Pota- momya, Serpula - Sands - - - Greenish marl and many clay with bands of Potamomya - Limestone with Tiana and Plunorbis. Fer- ruginous outside. Cyreni ? - Purple calcareous marl, with crushed shells - Strong lignite band - - - - Limnzan limestone : = Greenish clay and sand - - Hrapvon Hix Sanps (pale grey sand) - -—— AOOCWS an CCUM > wo | Total - = 153 2 A Section measured in Weston Chine, commencing at the bed marked (*) in the foregoing differs somewhat. Fr. In. ( Lignite - - - 038 Green marls, sandy clay, ae clay 3 Gor d 0 Green clay - -3to 0 6 Hard line of crushed Potamonya in bright ochreous sand - - - 0 2 Limnzan limestone; soft and earthy » 240 Greenish tenaceous clay, with carbonaceous matter, especially at the upper part. Planorbis and Limnea at the base. Throws out water - - - - - 1 6 Soft earthy Limnzwan limestone, impure and thinning away and is then marked by a line of shells - 0 6 Pale green sandy marl, with "Paludina, Pota- momya, &c. in the lower 3 in. which bes comes harder and more marly - - 1 6 134 GEOLOGY OF THE ISLE OF WIGILT, Fr. Iv Hard irregular band of sandy marl; green and brown and containing ferruginons patches ; — 2 eto Od Lower Headon < ee with an undulating lnregur head Beds, Pale-green marly sand or sandy marl din. to 0 6 Light-grey sand, with occasional bright ferru- ginous stains in lines and patches. Pota- momya at the base - - . - I 6 Verdigris-green marls and clays, with occa- sional Paludina and lines of Potamomya in the lower 6 inches - - - 5 0 Limestone (second ledge of the Chine). Potamomya at the top, Limnea, Planorbis. 6inchesto O 8 Light-grey sands, becoming ferruginous to- wards the bottom - - - 3to 1 6 Line of lignite linch. Hard band of variable thickness 1 inch. Imperfect limestone with Limnea, Planorbis, Paludina (Lignite sometimes disappearing) 3 inches 0 9 Light-green clay weathering brown and be- coming harder and concretionary at the base +$ feet and sands, clays and marls at the upper 3 feet - - band) a ' The detailed sections given above will show how thin and variable are the minor divisions which go to make up the Headon Beds at the western end of the Island. This variability largely accounts for the difficulty that is sometimes felt in correlating the beds at Headon Hill with those in Colwell Bay. But if instead of attempting to compare isolated sections, certain marked beds are followed continuously through the cliff, the connexion becomes much clearer.* So many geologists visit this part of the Island that it will be useful to add a few notes which may assist in the tracing of the beds, and in the identification of the principal fossiliterous zones where the connexion is hidden by landslips. To obtain a general idea of the structure of the beds, it will be desirable first to examine the cliff from a boat at a distance of half or three-quarters of a mile off Totland, though a very good view may be obtained from the end of Totland Pier. By thus first examining the cliff from a distance, one is enabled to re- cognisc the true structure of the Oligocene Beds, and is not so liable to be misled by changes in the direction of the coast, or by landslips-—both fertile sources of error in estimating the relative position or dip of beds in these soft deposits. Examined this way, the coast section shows that there is a high northerly dip at the west end of Headon Hill, where the cliff runs north and south, but that directly the trend of the coast changes so that the cliff runs parallel to the axis of elevation, the dip apparently * A valuable horizontal section will be found in the paper by Messrs. Keeping and Tawney, “On the Beds at Headon Hili and Colwell Bay.” Quart. Journ. Geol. Soc., vol. Xxxyil. (1881) p. 85. ITEADON BEDS. 135 disappears. Another curvature of the coast, commencing near Widdick Chine, again shows the true northerly dip, but the angle is much lower, the distance from the line of greatest disturbance being greater. From this point there is a northward dip, till the Headon Beds sink beneath the sea-level a short distance north of the Chiff End Battery. There may be indications of a very slight anticline near the Totland Bay Hotel, but it seems scarcely more than a flattening of the beds for a short distance. When we attempt to trace the beds on the ground, the landslips at Headon Hill make it impossible to follow most of the horizons continuously, However, the thick limestone which forms so bold a feature all through the hill enables us to identify the beds above and below it. Commencing with the base, the Headon Hill Sands (the glass sands) can now only be traced for about 5 chains north of the Alum Bay Pier, though formerly they could be seen a short distance further. The extensive working of this sand in old times has much to do with the tumbled and obscure character of this part of the section. Then for a mile the foreshore is entirely occupied by fallen blocks and landslips and the sands are invisible. It is probable that they have really sunk beneath the sea-level for part of the distance, for the higher beds also apparently sink slightly in the middle uf the hill, where the distance from the line of disturbance is rather greater than at either end. At the east end of the landslip and 8 chains south-west of the boat-house at Widdick Chine, the base of the Headon Beds is again visible. The following section was measured at this point imnic- diately above the beach in May of the present year (1888) :— FEET. Lower Headon ~ Beds. } Clay. Black carbonaceous sana and brown sand : 9 Hegon fill cee ep : : ~ a Sands. Do ; 9 Fine white glass sand } proved by boring { = i 21 A similar section was seen by Prof. Forbes and H. W. Bristow when the original survey was made, and the junction of the Headon Hill Sands with the Lower Headon Beds was clearly laid open for examination. As Professor Judd had questioned the accuracy of the correla- tion of the sands seen at the base of the cliff with the glass sands at the other end of the hill, a Loring was made to a depth of 9 feet below the beach level. The buff sand in the upper part might have been referred to either division, for the upper part of the Headon Hill Sands is generally stained for a depth of several feet. But the underlying pure white sands are so unlike any- thing found in the Headon Beds, that it was not thought neces- sary to carry the boring deeper, especially as the amount of water 136 GEOLOGY OF THE ISLE OF WIGHT. Fia. 36. Vertical Section of the Beds at the North-East Corner of Headon Upper Headon. Middle Headon. Lower Headon. Fill. (Scale, 8 feet to the inch.) (Reproduced, by permission, from the Quart. Journ. Geol. Soc,, vol. xxxvii. (1851), p. 91.) 63-8 0 0 3 (9 in-2 ft. Gin, 6 in. ft. in. 110 8 6 seen, Part of thick Limnea limestone. Linnea fusiformis, &e. Laminated greenish clay, with broken Paludina. Whity-brown to buff sands, with layers of lignitie matter. 2 Potamomya, Melania murvicata, Unio paveisancds DElOWw Lora vip ty > 0; Greyer sands below < Paludina lenta. Lignite. Greenish-gr¢ 7 clays! _ C. ( Vicarya concava, Marginella vit- ventricosum bed with 4 tata,Neritina concava, Melania t muricata, ce. Limnea limestone soft ane crumbling, with a thin lignite at top. Verdigris-green clay, with rootlets. Limnea-limestones. Stiff green clays with conchoidal fracture in drying. Oyster-bed towards the base. (Pususlabiatus, Mel.fasciata M. muri- Clay becoming ereyer | cata, Nerita aperta, Cer. variabile, i olawa moose 1 C pseudocinctw, Ostrea velata, Mytilus affinis, Corbicula obovata, Lucinea colvellensis. Alternating grey and ochry clays. (Cyth. incrassata, Mactra fasti« | giata, Mya angustata, Cor- Venus-bed,” richest por- d t ( tion, contains BeNEtONee bicula obovata, Nucula lissa, flints, brown sandy clay. N. headone nsis, Trig. deltoi- becoming gr 1 | dea, Pusus labiatus, Cancell. elongata, Melanop: Susi- Jormis, Voluta spinosa, Vic. concava, Natica Sluderi. Thin grey sandy clays, weathering brown. sand beloy Cytherea incrassata, &ec. scattered throughout. Mya angustata, especially near base. Chocolate-brown or ¢ Trig. delloidea. Cer. pseudocinctum, blackish sands. @ Natica labellata, Melan. fusiformis. Trigonocelia-hed. Blackish-brown sands, Verilina bed Seas, oe a x Be E . formis, C. obovata. Very stilf tenacious clay. Limnea-limestone, “Wow-Ledge lime-¢ Z. longiscata, fusi« stone, t formis, &e. Whity-brown or yellow sands and fi sand-rock, with layers of Paludina and Potamomya. ; Ks [The base concealed by tumble and widercliff,7 NKEADON bups, 137 met with would have necessitated the use of lining tubes if it were to be continued. North of this point the dip quickly carries the base of the Headon Beds below the sea level. Returning to the western end of Headon Hill we find a thick limestone forming the top of the cliff. The position of this lime- stone is close to the base of the Upper Headon Beds, and it over- lies a series of marine clays and sands fall of Cerithium, Ostrea, and Cythercvw. These marine beds belong to the Middle Headon Series, but unfortunately they are not at the present time clearly exposed, except at the two ends of the Hill. From this point the marine beds are almost entirely hidden by landslips for about a mile but the limestone can be followed, and ina similar position below it at the north-eastern end of the hill the marine beds again occur. Part of these can be well examined at the present time, though they are not easy to find unless one has firet identified the thick Limnzan limestone. Messrs. Keeping and Tawney give a sarefully measured section at this point, which is here reproduced, Fig. 36 (sce page 136). The base of the thick Upper Headon Limnaan limestone at the point where it leaves the coast is about 120 feet above the sea, and at the north-eastern end of the Headon Hill outlier it has fallen to about 110 feet. Crossing the small valley which divides Headon Hill from a lower hill nearer Middleton, we find the thick limestone at a height of 130 feet. From this point it falls in less than a quarter of a mile to about 110 fect. Then it flattens for another quarter of a mile, and remains at the same level at the northern extremity of the outlier near Amos Full. Returning to the coast we find the Oyster Beds in the marine Middle Headon Beds about 95 feet above the sea at the point where the cliff becomes low near Widdick Chine. Half a mile to the north-east there is a small hill on the northern side of Weston Chine which just reaches 100 feet. The upper part of this hill is oceupied by a brick-yard, and 7 feet down in the clay, 1.¢., at about 93 feet, the Oyster Bed is again found. It is full of fossils, but they are not well preserved; the species noted were Ostrea velutu, Cytherea incrassata, and Buerinum labiatum. Thus the same flattening of the beds for a short distance occurs here which we have already noticed in the limestone. Still further inland, to the north-east, the Oyster Bed is again met with in a large brick-yard near Amos Cottage. Here the height is about 60 feet. In this brick-yard the fossils are all in the state of casts, and only Ostrea relate and Cytherea incrassata could be determined. Returning to Totland Bay, we find the dip to become higher and the marine beds again to strike the cliff a few chains north of the Coast Guard station, at a height of about 80 fect. From this point these beds can be followed continuously, except in the parts under Warden Battery, and over short distances where the face of the cliff is obscured by talus. A few yards north of How 138 GEOLOGY OF 11% ISLE OF WIGIUT. Ledge the base of the marine beds falls to the level of the beach, and from thix point nearly to Linstone Chine continuous sections are generally exposed, for there is little talus, and the lower part of the cliff is so full of fossils that it presents a vertical face. The thickening vf the Oyster Bed, and the way in which it cuts into the underlying clay full of Cytherea, are very noticeable in this part of the cliff. We have now reached the section which all geologists visit, and from which the majority of the marine Headon fossils have been obtained. It may therefore be well to stop for a moment to point out that even this most purely marine portion of the Headon series is full of freshwater shells. A few minutes search is sure to yield several specimens of Limnea and Cyrenw wixed with the Oysters. The underlying clay full of Cythercu is more thoroughly marine, but it also contains a good many valves of Cyrene. However there is « decided and essential difference between these marine beds with drifted freshwater shells, and the beds full of Potamomyn, Melania, and Potamides, which lie above and below them. These fossils probably point to deposition in brackish-water lagoons and not in the open sea. Like all accumulations formed in such conditions, therefore they contain abundance of individuals belonging to very few species, instead of a wonderfully varied molluscan fauna like that of the Middle Ieadon Beds. The How Ledge limestone, which underlies the marine bed, is another well-marked horizon. This stone is a band, from 3 to 5 feet thick, of freshwater rather tufaceous limestone full of well preserved Limueu and Plunorbis, belonging to many species. The perfect preservation of the fossils, the softness of the matrix, and the ease with which the bed can be examined, render this the favourite bed from which to obtain these shells. The rock is always visible between How Ledge and Warden Point, and can be traced continuously southward to the Coast Guard Station. Here it passes inland, but Messrs. Keeping and Tawney identify it with the Limnean limestone at the top of the Lower Headon Beds at the north-eastern end of Headon Hill (see section p. 136). A section of the lower part of the cliff near Colwell Chine, given at p. 242, shows the small reversed or overthrust faults developed in this limestone by lateral pressure connected with the formation of the great uniclinal fold of the Isle of Wight. A short distance below the How Ledge limestone is a mass of calcareous concretionary sandstone and sand, forming Warden Ledge. This sand is traceable at intervals for about a mile. South of Warden Ledge other thin limestones form a minor ledve ee Ok 5 on the foreshore. These limestones, full of Chara and Limnea, can be traced nearly to Widdick Chine. The sections of the Headon Beds near Clif End are, un- fortunately, semewhat obscure at present (1889), and the thinning out of the thick Upper Headon limestone renders it difficult to trace the northward limit of the Ileadon Leds. Messrs. Keeping and ‘Tawney identify the thick limestone of Headon Hill with a bed HEADON BRDs. 139 1 foot 8 inches thick at Cliff End.* This correlation is probably correct, but it has been found impossible to connect the beds by mapping. Inland sections of the Headon Beds are rare—at least sections which yield any evidence of definite horizons scldom occur. A very fossiliferous section is exposed in a miniature chine, cut between the north-east corner of Freshwater (All Saints) Church- yard and the marsh. A good deal of gravel has slipped over the beds, which are only clear at the bottom of the channel, so that it was impossible to uvbtain any measurements. The principal fossiliferous bed consists of a mass of shells in a slightly hardened sandy matrix. The species collected in 1887 were Planorbis obtusus, Neritina concava, Nematura parvula, Melania muricata, Melanopsis subfusiformis, Limnea longiscata? Hydrobia Chasteli, Cerithium elegans, Cyrena obovata, Cyrena deperdita, Serpula, Charu. The specimens of Neritina are particularly fine, being unusually large, and with the colour well preserved. Another manuscript list of fossils from ‘‘ Wheatlow Brook, near Treshwater Church” (apparently the same locality), gives Ancil- laria bueccinoides, Cerithium concavum, C. elegans, C. mutabile, Melanopsis fusiformis, M. carinata, Natica depressa, Nerita aperta, Neritina concava, Paludina lenta, Cyrena obovata. These fossils were collected about 1852.t In both cases the beds seem to belong to the base of the Middle Headon Beds—the “Neritina Bed” of the coast section. The well at Golden Hill Fort must have penetrated almost the entire thickness of the Headon Beds, but unfortunately the record of this well has been kept in such a way as to render it almost useless for geological purposes. The section will be found in the Appendix. Besides those mentioned, there were several temporary sections near Freshwater, showine clays with Potamomya and Puludine. A well at Poundgreen, 7 chains north-east of the cross-roads, seems to have reached the Headon Hill Sands. It showed :— Lower Headon f Green clay with Paludina and Potamomya. Beds. Black clay with crushed Planorbis. Sand. The thickness of the beds could not be ascertained. Crossing the Yar, the old marl pits near the Yarmouth road are in green clay, with Potamomya—probably Lower Headon, but no section is now visible. East of these pits the dip becomes high, and there are no exposures for three miles. Near Little Chessell the beds again flatten somewhat, and sections of the shelly Middle Headon Series can be seen extending for several chains along the stream course about a quarter of a * Op. cit. p- 90. nae i + I cannot learn definitely who supplied this list or who collected or determined these fossils (though Mr. Bristow thinks it was the late Mr. W. H. Baily), and am unable to find any place named Wheatlow Brook, near Freshwater.—C. R. 140 GEOLOGY OF THE ISLE OF WIGHT, mile north-cast of the farm. Here the following species were collected by J. Rhodes, the fossil collector of the Survey :— Chara. Cerithium elegans. Hydrobia, sp. (young). Cyrena obovata. Melania muricata. Cytherea incrassata. Melanopsis subfusiformis. ‘Tellina, sp. Natica labellata. Nematura parvula. Ancillaria buccinoides. Neritina concava. Buccinum labiatum. Pleurotoma headonensis. The Cerithium is very abundant, in a shelly sand, and there is also a bed of clay full of Cytherea, but it is difficult to make out the true succession. Further north, about 8 chains south of Eades Farm, a ditch section shows clay full of Potamomyu gregaria, On the opposite side of the stream fossils are ploughed up abundantly in the fields. Those collected by J. Rhodes were Cyrenu deperdita, C. obovata, Aydrohia Chasteli, Melanopsis carinata, Melania muricuta, Neriting concara, Nematura parvula, and Planorbis, There is nothing among these to show to what part of the Headon Series this shelly clay belongs. From Newbridge eastward to the Medina, the beds are nearly vertical. Not a single section of the Headon Series is now visible there. At Newport, though the beds cannot be examined at the surface, the whole thickness of the Upper and Middle Headon strata seems to have been penetrated in a well at Messrs. Mow and Company's Brewery (see Appendix, p.305). It is not easy to fix the boundary between the Osborne and the Headon Beds, but taking it as occurring at 259 feet from the surface, we have thick- ness of 189 feet down to the sand which yielded water. Of the 189 feet of Headon Beds, at least 82 feet should be referred to the Upper Headon, and the remainder to the marine Middl Headon. Any attempt to correlate the minor subdivisions would be unsafe, for the samples preserved were small, and the thickness of the different beds appears to have been greatly increased by lateral pressure. Within a few hundred yards of this well lics the area of sharpest folding. At West Cowes another well has been sunk to supply the town (see Appendix, p. 313). Here again the boundary between the Osborne and the Headon Series is very difficult to fix, but it seems to lie about 268 feet from the surface. At 365 feet, ic., 47 feet below the top of the Headon Series, the shelly “ Venus Bed,” commences, and from a sample of clay brought up from that depth the following species were obtained :—Cytherca tnerassata, Cyrena, sp. Buecinian labiatum, Natien labellata, Nemutura parruly, and an otohth of fish, From 375 feet a sample of ereen clay contained Nutiew and indeterminable shell fragments. From the spoil heap at the well a considerable number of species were obtained, and though the exact depth from which they came could not be fixed, they certainly belong to the clays at about 114 fect. The species collected were :-— HEADON BEDS. 141 Cardita simplex. Buecinum labiatum. Cytherea incrassata. Bulla, sp. Corbula cuspidata. Cancellaria elongata. — pisum, Cerithium elegans. Cyrena deperdita. Natica labellata. obovata. Pleurotoma plebia. Ostrea ventilabrum. Rostellaria, sp. Voluta geminata. The occurrence of Curditu simplex and Voluta geminata is inter- esting, for these are Brockenhurst specics previously rare or un- recorded from the Isle of Wight. Both are abundant in this well. Between 420 and 434 feet grey shelly sand with Mutica, Pleurotoma, Nematura, Potamomya, Cyrena, and Planorbis occurs, so the Middle Headon Beds seem to be at least 113 feet thick. This thickness is much greater than at the west end of the island but agrees very well with the Whitecliff Bay section. The increase of thickness of the marine beds is apparently due to the incoming of the Brockenhurst beds, which are absent towards the west. Below the sand the boring penetrated 3 feet into clay, in which no fossils were ebserved. This clay ought perbaps to be referred to the Lower Headon Series, for the occurrence of Potamomya and Planorbis in the bed above seems to indicate a change of conditions at this point, but unfortunately the boring was carried no deeper. Another well, at Woodvale (see Appendix, p. 315), a short distance from the last section, penetrates about 13 feet into the Middle Headon Beds, with Potumomya greyuria, Cyrena obovata, Ostrea, Melania murtcata, Cerithium concavum, C. trizonutuim ? The beds seem to correspond with those seen on the foreshore at Osborne. The Headon Beds reap ear for a short distance at the extreme northern point of the Islund, brought up by a local undulation connected with the rise of the beds on the north side of the Isle of Wight syncline. During the progress of the first Survey of the Island these beds were well seen at the foot of the cliff near Osborne and Norris Castle. But now the building of the sea walls and the erection of groynes has almost entirely hidden the sections, though abundance of Certthinm concavum can still be found on the beach. The following description of the beds is entirely taken from the first edition of this Memoir :— Due north of East Cowes, a little round the first Point, light- green and red sandy clays, with bands of compressed Melania costata. and bivalves, forming a shell-marl, have slipped from a higher level on to the shore, and Paludinu fenta, Cyrena obovuta, Potamides (Cerithium) concavum, often in a silicified condition, lie scattered in great profusion on the beach. Immediately under these, apparently, and seen also on the shore, are 1 to 2 feet of greenish-grey clays, with occasional sandy lamine, and numerous bands of Potamonya sparingly mingled with Paludinu lenta, Cyrena obovata, and an oceasional C. pdchra, Bands of crushed Paludina lenta oceur lower down, succeeded by bands of Melanopsis, with remains of Fish (scales, vertebra, 142 GEOLOGY OF THE ISLE OF WIGHT. and teeth). Green sandy clays follow, with thin pyritised bands of shells, a band of Limnea longiscuta and smaller subordinate layers of Potamomyu. Here the beds undulate, and towards the point above Norris lower beds make their appearance. West of the Point green clays are seen at the base of the cliff 4 inches thick, under a 2-inch band of clay-ironstone. These clays contain Jelunia turritissima t and a black Cypris, Upon the clay-ironstone lies a band of Cyrena pulehra followed by greenish clay 1 foot thick, full of Cyrena obovata, occasionally with the valves in contact, and most numerous towards the upper part. Three feet beneath the ironstone another similar band occurs, separated trom the first by green clays, with five or six bands of Potamomyu. Below the second band of ironstone green clays, with Oysters succeed, associated with Cyrena pulchra, C. oboruta, Cerithium, &e. On the shore, about 50 yards westward from the wall of Norris, pyritiferous bands of Potamomya underlie the green clay with oysters, and the section may be there continued as follows :— Fr. In. Green sandy clays, with an oyster-band 2 inches thick - 1 6 Grey sands, fossiliferous in the upper part, where they are also laminated, and passing into ferruginous grit —- 26 Light-greyish clayey sands, with 2 inches of Potamomya in the upper part - - - 4.0 Beds not seen - - 3 or 4.0 Greeuish sands, with We/lania muricata and Potamomya — - Greenish clay, with a few Potamomya 1 0 Consolidated and partly pyritised bands of Pvotomomya, Helieen which are layers of greenish sandy clay full of Chara, fish-scales, and AMelania muricata in patches - - 5.0 Light-green sandy clay, with comminuted Cyrena North of Norris, by the sea-wall, the beds on the shore at the Point are crowded with Cyrene oborata and Patumides ; Cyrena pulchra and oysters being somewhat scarce. The shells already noticed as being so plentiful on the beach nearer East Cowes are probably derived from these beds, which are most likely lower than those with consolidated bands deserihcd in the preceding section. Opposite the Point they are probably covered by the sca. Hence to the wall separating the Royal erounds from those of Norris the strata are concealed; but on the shore opposite the latter, sands with Potimnides, Cyr ene, and Oysters, again appear. East of Cowes and Newport there are no sections of the Headon Beds till Whitechff Bay is reached. However the trial borings Nos. 116, 117, and 118, about two miles east of New port, indicated feahwaier beds belongine to the Headon Series, though they yielded no characteristic fossils. At Whitecliff Bay the Headon Beds are 212 feet thick, and are divisible, as in other parts of the island, into three sections— a middle marine, and an upper and a lower treshwater and estuarine. The following section is that measured during the original Survey, with some corrections and »dditions made in 88s -— Upper Headon Beds, 58 feet. Middle Headon Beds, 126 feet. Lower Headon Beds, 28+ feet. SIEADON BEDs. Headon Beds in Whitecliff Bay. ( Grey, reddish, bluish and ash-coloured laminated clays. Layers of Potamomya gregaria, with occasional Paludina lenta, Melania 2 sp., Fish-scales, Serpula on the Paludina and Potamomya - Grey laminated clays. Unio, Cyrena obovata Sandy clay with calcareous concretions. Limnea caudata, Chara Wrightii - - Ferruginous sands and calcareous hard bands. é Hydrobia, &c. - - Green clay, with Cyrena obovata - Brown clay, without fossils - - Yellow sand, without fossils - - Marl and green clay with calcareous concre- tions. Cyrena obovata, Limnea longiscata, Planorbis ewomphalus, pieces of wood White sand with thin layers of whitish clay - Alternations of carbonaceous clays and greenish sands. Cyrena obovata, Potamides, Chara Wrightt— - - : Green sandy loam, with a few casts of marine shells. Psammobia compressa, Cytherea imerassata, Cyrena - - Blue sandy clay. Cytherea inerassata very abundant at the top; Cerithium pseudo- cinctum Stiff blue clay, full of fossils. Cytherea in- crassata, Psammobia compressa, Cyrenu obovata, Fusus labiatus, Cancellaria elongata, C. muricata, Natica labellata - Sand or sandy greenish clay weathering brown. Ironstone nodules. Casts of < _ marine shells - - Brown sandy clay, often with nodules con- taining marine shells and fish-remains. Cardita deltoidea, &c. Brown clay, containing pieces of the under- lying clay and flint-pebbles, and full of marine shells. Ostrea, Modiola, Cardium, Cardita deltoidea, Cytherea incrassata, Calyptrea, sp. Fusus, Voluta spinosa, V. geminata, &c. (Messrs. Keeping and ‘Tawney record 62 species of mollusca from this bed and compare it with the Brocken- | hurst zone of the New Forest) [Green freshwater marls, with seams of Pota- momya plana, Planorhis, Limnea, &c. Grey sandy clay - - - Hard ferruginous sandstone - - - Pale-green clays, with seams of lignite, and ironstone nodules. Palndina lenta, Limnea. Planorbis euomphalus, P. obtusus, &c. Green clay, ferruginous at the base. No fossils observed —- - | | Carhonaceous clay and lignite - - | L Total 143 Fr. In, 2 0 5 0 10 L 0 } 5 0 10 0 1b 0 4 0 5 0 2. 0 PO 0 4 0 76 0 lv 0 2 0 8 0 7 0 0 3 80 1 0 4 0 212 3 Here, as at Cowes, there seems to be « tendency in the marine bands to thicken at the expense of the estuarine Lower Headon Beds. These marine bands become more thoroughly marine, losing 144 GEOLOGY OF THE ISLE OF WIGHT. to a large extent the admixture of freshwater shells which is so conspicuous at the west end of the Island. The tufaceous fresh- water limestones have all died out, and most of the purely freshwater beds seem to be largely replaced by beds of estuarine origin. However, the occurrence of derivative fragments of the underlying freshwater clays at the base of the marine beds, shows that the thinning out of the lower series may be due to actual erosion, and not to a replacement by contemporaneous beds of marine origin. Messrs. Keeping and ‘Tawney record the occurrence of a similar line of erosion at the base of the Brockenhurst Beds in the New Forest. In Whitecliff Bay two principal horizons in the marine beds yield most of the fossils. The lowest zone is about 30 feet from the base of the Headon Series and the greater part of the fossils are crowded into a seam a few inches thick, The most abundant species are the Ostrea, Nucula, Car- Fig. 37. dita acuticosta, Cytherea incrassata Cytherea incrassata, Desh (Fig: 37), Pleurotoma, and Voluta Fs spmosa, The other bed is a shaly clay about 90 feet higher. This latter seems to correspon with the “ Venus Bed” of Colwell Bay, and contains a similar assemblage of fossils. Amone the common species are Cytherea incras- sata, Corbula deltoidea, Ostrea, San- gidtotunt ta, Certthium pseudo- cinctum, Voluta spinosa, &e. A large number of the marine mollusca of the Headon Beds range downwards into the Barton Clay, but about half are peculiar to the Oligocene. This apparent break between the Eocene and the Oligocene will probably disappear when the marine fossils of the Lomwer Headon Beds and of the Headon Hill Sands are better known, but at present it is sufficiently marked. Cytherea merassata, Fig. 38. though especially abun- Ostrea flabellula, Liam. dant in the Middle Hea- don Series, has 2 some- what extended range, from the Barton Clay: to NY the Bembridee Beds. It “\\ gives the name to the \\ \ well known “ Venus bed” \ of collectors, the C 'ytherca / having formerly been \) enowa as Venus ctneras- sate Among the other abundant marine bivalves may be mentioned the Ostrea velata, which forms thick banks in Colwell Bay, and the Ostrea fabellula ¢ (Fig. 38), a much scarcer species which ranges HEADON BEDS 145 downward into the Barton Clay but does not occur above the Headon Series. Nucula headonensis is also very plentiful in Colwell Bay. iF . ‘a . . The estuarine and freshwater bivalves most commonly met with are species of Potumomya (Fig. 39) and Cyrena. These oceur in Fre. 39. Potamomya plana, Sow. vast numbers in certain beds. Unios (Fig. 40) are more rare and are generally confined to thin seams. Fig. 40. Unio Solandri, Sow. The most plentiful univalves in the marine and estuarine beds are several species of Certthinm, including C. concarum (Fig. 41) and C. pseudo-cinctum (Fig. 43), Melanopsis subfusiformis (Fig. 42), Buccinum labiatum, Murex seadentatus, Nerita aperta, Fig. 41. Fie. 43. Cerithium Cerithium concavum, Sow. Fig. 42. pseudo-cinctum, D’ Orb, Melanopsis subfusiformis, Morris. Neritina concava, Ancillaria buccinoides, Melania muricata, and several species of Cancellaria, Nautica, Pleurotoma, and Voluta. E 56786. K 146 GEOLOGY OF THE ISLE OF WIGHT The mollusca of the freshwater limestones are nearly all Limneids belonging to the genera Limnea and Planorbis, Limnea longiscata (Fig. 45), and Planorbis euomphalus (Fig. 44), Fig. 44. Fie. 45. Planorbis ewomphalus, Sow. Limnea longiscata, Sow. NY WYNE being perhaps the most abundant and conspicuous species. Paludina lenta (Fig. 46) is a very abundant Species: throughout the Oligocene Beds, especially in the fresh- Fra. 46. water clays and marls. Nematura parvula Paludina lenta, Sow. is very plentiful, and more generally dis- tributed than is often thought, for its small size causes it to be overlooked. There is also a considerable number of species of land-shells scattered through the lime- stones, but these are not so often met with. They however point to the close proximity of the shore, Of other fossils the most commonly found are valves of Balanus unguiformis in the marine beds, and nucules of Chara, generally C. Wrightii (Fic. 47) in almost any part of the series, but especially in the Neritina-bed at the base of the Middle Fig. 47. Headon beds. Vertebrate remains are Ohara Wiese: Morten eee a Except Chara, : iere arc few recognisable plants. “ Like the other Oligocene beds, the Headon Series seems to be mainly of lagoon or estuarine origin. In the Middle division we have truly marine beds, but these are interbedded with others deposited in brackish water. The Upper and Lower Headon Beds are mainly fresh, or brackish-water deposits, and there seems to be an entire absence in them of purely marine genera, such as Voluta, Ancillaria, Pleurotoma, Natica and Cytherea, IIEADON BEDs. 147 Every variation in the amount of salt in the water seems to have been marked by a change in the fauna. The purely freshwater beds contain few mollusca except Limnea, Planorbis, Paludina, Unio, and land-shells. The different species of Potumomya, Cyrena, Cerithium (Potamides), Melania, and Melanopsis wppear nearly all to have liked water containing more or less salt. So we have a gradual change to beds containing Oysters, and then to beds with Volutes. Besides these indications of varying conditions, it is interesting to observe a general tendency in the beds to become more fresh- water towards the south-west, while tufaceous limestones appear in that direction. The land-shells also point to the proximity of land, as do the pebbles of flint.* Unfortunately at the point wherv the most rapid changes are taking place—at Headon Hill—the beds have been cut off by denudation. We cannot therefore see whether the beds show any tendency to overlap each other, or to overlap the underlying Eocene. * Pebbles of Chalk have been recorded, but they appear to be really white flints. The flint pebbles in the Headon Beds are sometimes weathered to the centre 148 GEOLOGY OF THE ISLE OF WIGHT. CHAPTER XI. OLIGOCENE— continued. OsBoRNE Beps. Between the Upper Headon beds, containing Potamomya and the Bembridge Limestone, intervenes a series of strata to which the name of “ St. Helen’s Series” was originally applied by Professor Forbes in consequence of the “ conspicuous features presented by them between St. Helen’s and Ryde.” This designation was, however, subsequently changed by Professor Forbes to “the Osborne Series,” on account of their being displayed in the cliffs and grounds of the Royal demesne,—a small distance to the east underlying the Bembridge Limestone, and a little to the west in conjunction with the Upper Eeadon beds, with which they do not appear in connexion at the locality after which they were named in the first instance. The total thickness of the Osborne Beds varies from about 80 feet at each end of the island to 110 feet at Cowes and Newport. Commencing at the western end of the island it will be per- ceived, on comparing the sections of the Osborne beds at Headon Hill with those at Clit? End, that the thick bed of concretionary limestone seen in the former locality altogether disappears in the latter, where it is most probably represented by the mottled clays and marls in which the remains of Z'wrtle are found, and by the clays with paie-green nodular concretions containmg Limuea longiscata, Paludinu globulvides, &e. Osborne Series ut Headon Hill. Fr. In Whitish (passing into red and blue) marls, with occasional hard bands, and courses of nodular concretions of light-grey argil- Jaceous limestone in which occur traces of shells and turtle bones. In the concretions are Linnea longiscata, Planorbis discus, P. obtusus, P. oligyratus, Paiudina, sp. - - = 4o 0 Grey shale, with crushed Paludina lenta, fish-vertebrae, &c. - Ferruginous and nodular band - : “ a Grey shale, Paludina lenta, Melunopsis carinata, Melania costata. 7 0 The Fisu and PLrant Bups : S Yellow, red, and blue sandy clays - 30 Thick concretionary limestone, with silicious concretions sometimes of large size and used for building. ‘This band almost disappears northward. Fossils scarce. Linu lonyiseuta, Planorbis euom- phalus, P. lens, Paludina lenta : 3 : 18 0 Greenish-white calcareous clay s % : 4 0 Sandy ferruginous band - > 2 - " 2 0 7490 —— a OSBORNE BEDS. 149 C. Warden Point d. Middle Headon series. c. Upper Headon series. Fie. 48, Diagram of Colwell Bay Clif’s (by Edward Forbes). B. Colwell Bay. ce. Lower Headon series. b. Osborne series. A. Cliff End and Sconce Point. a. Sconce (Bembridge Limestone). The concretionary limestone can be traced inland towards Mid- dleton, forming « pold feature in the hill, At the old limekilns near Greens it contains Bulimus ellipticus, Limnea, and teeth 150 GEOLOGY OF THE ISLE OF WIGHT. of Paleotherium minus? This rock was formerly referred to the Bembridge Limestone, but both its lithological character and its continuity witb the concretionary limestone of the coast show that it ought to be referred to the Osborne Series. Between Headon Hill and Linstone Chine as will be perceived by Forbes’ sketch (Fig. 48, page 149) the Osborne Series has been removed by denudation, and the cliffs consist of the subjacent tleadon Beds. At Cliff End it reappears beneath the battery, and can then be traced at short intervals along the coast nearly to the river Yar. The Osborne Beds in this locality were examined by Professor Forbes and H. W. Bristow in 1852. Forbes revisited them twice in the spring and autumn of the following year (1853), and in the present year (1888) they have been re-examined and partly re-measured. Owing to the constant landslips considerable difficulty attends the determination of the relative importance of the several beds. ‘The increased thickness here accepted for the lower part agrees so well with what has been obtained at other sections, and was proved so carefully by levelling, that some of the original measurements must evidently have been taken from a slipped mass. Osborne Beds at Cliff End. FEET. Bluish sandy and marly clays. Cyrena obovata (this bed is now invisible) - - About 10 Red and blue marls, with lines of nodular concretions of agillaceous limestone in which fossils occur occasionally = - - 25 to 30 Dark-grey shales, with an ironstone band in the centre. Leaves, Insects, and Fish ; Candona, Paludina lenta, Melanopsis carinata, Melania costata, Lepidosteus, Alligator. (Probably the equivalent of the Fisu Ben.) - : - - - - 7 Reddish and bluish clayey marls, with greenish nodules containing shells; turtle; Limnea longiscata, Hydrobia, and Paludina globuloides - - - - 40 82 to 92 Following the Osborne Series eastward, we can detect inliers of mottled clay in the plateau formed by the Bembridge Limestone south of Wellow, but no measurements can be obtained. Returning to the coast, we find these beds to be concealed for four miles by newer formations which occupy the whole of the cliff. However red and green clays reappear from under the limestone on the east side of the Newtown River, and can be examined for « depth of about 30 feet in the cliff and in a brickyard. No fossils were seen. Half a mile further east the Osborne Beds again sink beneath the sea-level and are lost for two and a half miles. At Gurnard Ledge the mottled clays reappear, but between this point and Cowes they call for no detailed description, being almost unfossiliferous and generally much obscured by landslips OSBORNE BEDS. 151 The cliffs near Osborne having now been carefully sloped and planted, in this typical locality for the Osborne Series we can only follow Morbes, and the following is his description of the beds. Osborne Series near Osborne. _ “The slips and slopes at the eastern portion of the shore at Osboriie* show mottled red and green clays, overlying a limestone composed of broken shells and containing Melania costata and Melanopsis brevis. On the shore lie flags of i C . : % pes _.. sandstone with fucoidal markings, and blocks of “Wo coe a greenish sandstone containing casts of Paludina orbes. lenta, often weathered in high relief, MWelania excavata, and a large-bodied Limnea of consider- able size. Among the marls are layers containing entire shells of Melanopsis carinata, srasll Palu- dine or Hydrobie, and Chara nucules in abun- dance. This appears to be an excellent locality for fossils.” “Opposite the lawu that stretches down to the sea in the grounds at Osborne, there are no hard beds or rock masses exposed on shore, bat immediately to the west of the landing pier are strata of exceeding interest, for here we see marls and shales belonging to the upper part of the Headon Series. On the shore by the pier outcrops of beds of tenaceous greenish blue clay are exposed, full of Cyrena obovata, mingled with Paludina lenta ; and in the clay beds in which the foundations of the sea wall are placed are Cerithia, At aheight of about 20 feet above the shore is a stratum of ragstone, an imperfect limestone, 2 fect or more thick, thickening more westward and thinning out castwara. The ragstone makes but bad me. Higher up is a sandy limestone, and bands of comminuted shell stone, separated from the rag by marls. In fragments of the limestone I observed numbers of Paludina lenta, accompanied by peculiar large-bodied Limnee of considerable size, and occasional lines of OUniones, somewhat resembling U. Solandri in outline, but a larger shell. The Palu- dine were often lying loose in their cavities, and had their shells frequently preserved. I found portions of a large Planorbis, apparently P. euomphalus ; also Planorbis obtusus, and another, P. platystoma, Melania excavata and lines of broken Cyrene occurred in a gritty band. Pale blue and purple shales, about 10 feet thick, capping yellow sands that become white eastwards, surmount the grits, and are succeeded by ferruginous marly and stony bands containing casts of Paludina lenta, hollow and having their cavities lined with crystals of cale-spar, Linnea and Planorbis. Dark shales, with partings of Cyrena obovata, form the highest portions of the broken cliff The details of this important section are obscured by land slips and cultivation, but it is evident that here the ground to the surface is occupied by “ The old name of Osborne, according to Worsley, was Austerborne. 152 GEOLOGY OF THE ISLE OF WIGHT. typical beds of the Osborne Series, those on the western side of the lawn belonging to the lower or Nettlestone division, whilst eastwards we find the members of the higher or St. Helen’s group. The Osborne section is peculiarly interesting for the link that it affords between the very different aspects of these beds at Cliff End as compared with those at St. Helen’s.” A section in red and mottled clays of the Osborne Series is seen in the East Cowes Park Brick-yard. Here J. Rhodes obtained Chara, impressions of plants, casts of Linnea, Fish vertebre, scales of Lepidostens, Chelone, Trionyx, Crocodile, und the astragalus of a small mammal. During May of the present year (1888) the Osborne Beds near Ryde were re-examined, under the guidance of Mr. Colenutt, who has paid special attention to this division. The principal point of interest. was the occurrence of a bed of clay in which are multi- tudes of small fish (Clwpea vectensis), evidently suddenly killed and buried before they had time to decay. The thin seam in which these occur is difficult to find, but such has been the minuteness of Mr. Colenutt’s examination that he has been able to trace it from King’s Quay, near Osborne, tu Sea View.* The first locality at which these fish were discovered was near Ryde House, but during this visit the section was obscured at that point, though another one was measured close to King’s Quay. Here the cliff is so obseured by landslips and so much overgrown, that the exact position of the Bembridge Limestone cannot be fixed, and only the beds on the foreshore can be well seen. Though the measurements are only approximate, the changes of character and colour of the different clays are sufficiently marked to enable the different beds to be recognised, The fish-bed is generally just below the level of high-water, and being slightly harder than the other clays it often projects through the beach. Section cust of King’s Quay (measured with the assistance of Mr. Colenutt). Fret. Bembridge Limestone. Red and mottled clay (only seen in landslips) - . - About 40 Green clay, with scattered fish bones. Scales and vertebra of Lepidosteus abundant, Al/igator, Hmys, Trionyx, and Chelone, Theridomys and snake vertebra - : - . - About 4 Hard grey shaly clay, full of fish bones, and whole fish (Clupea 2 vectensis) - - - : 7 H 2 Similar clay with grass-like leaves and lenticular masses of cement stones - - - & Es 3 Blue clay, with abundance of mollusca. Puludina /enta, Melanopsis carinata, &e. = - . - 3 6 Unfossiliferous green clay, to low water, 55 * Seo Geol. Mag., dec. III., vol. v. p. 358. (Aug. 1888.) The fish, which is new to science, has reeently Icen described hy BU. T. Newton under the uxme Clupea vectensis, See Quart. Journ. Geol. Soc., vol. xlv. p. 112. (Feb, 1889.) OSBORNE BEDS. 153 West of Binsiead Point, thirty teet of red and green marls are displayed at the base of the cliff, supporting hard light-ereen marl with small white concretions ; above this suecceds a thin band of decayed shells (forming a soft shelly limestone, the greater portion of which is composed of fr agments of bivalve shells s), with a sort of Iaminated appearance. The caleareous band contains commi- nuted Cyrena, Limnea longiscata, Unio, Melania excavata, Melan- opsis, Planorbis discus, &e., with two feet of interstratified sands and sandstones and grits above it, which sre probably the equiva- lents of the silicious beds beneath the Bembridge Limestone at the Binstead quarries. Two feet of soft sand complete the section. Fig. 50. Section at Binstead. a. Gravel. d. Marl. b. Sand. e. Grit. c. Grits. At Ryde House a ripple-marked flaggy sandstone (probably bed ¢ in ‘the above woodcut) immediately. overlies the fish bed. At Binstead Point the upper calcareous portion of the thick bed at Nettlestone comes to the shore, capped with green marls, and assumes the character of a hard and compact white limestone with Melania excavata. Westward of the Point it forms a ledge on the shore, which strikes nearly due west in the direction of Osborne. About a quarter of a mile east of the Point, sandstone appears, dipping 10° W. of 8S. at 5°. Gravel and the enclosed nature of the ground now conceal the strata for a considerable distance: but a few scattered blocks of grit lie under the sea-wall opposite the first houses west of the town of Ryde, and again midway between Ryde Pier and Apley. At the west corner of Apley Wood a bed of calcareous sand- stone, about four feet thick (full, in places, of casts of Paludina, associated with numerous large Unio, Limnea, Planorbis, and occasional bones of Turtle), appears on the shore beneath the sea- wall. The shells, which are as much crowded as in Sussex marble, are sometimes filled with a greenish marl, the rock itself being somewhat ferruginous, and of a pale ochreous colour. It rests upon ragstone similar to that at Nettlestone, ten feet or more thick, under which sandstone, in iayers eighteen inches thick, con- tinues to a depth of ten or eleven fect. Under all hes a strong 154 GEOLOGY OF THE ISLE OF WIGHT. greenish-blue clay for thirty feet more, which contained, apparently, crushed Paludina. Much of the stone used in the construction of the sea-wall has been obtained from the shore here, opposite the wood. Red and white clays are based upon the upper bed of stone; they are seen im the cliffs for a considerable distance, and have furnished the earth manufactured at the brick-pits inside Little Apley Wood. ‘The strata begin to arch from about this place, and in so doipg disclose a good section of the Osborne Series, especially between Nettlestone and St Helen’s, as far as Watch House Point, where the Bembridge Limestone rapidly descends to the shore. The centre of the arch is somewhere near the old Salterns, but among the fossils found, or the strata brought into view, there is no evi- dence of any portion of the Headon series being brought to the surface. From the semicircular projection halfway along the bay, to the notch in the coast near the eastern termination of the wood, hard beds with Char appear at intervals on the shore and beneath the sea-wall, dipping W.S.W. 2°. Opposite Puckpvol Farm, and be- tween the Point further east and Nettlestone, there is a broad expanse of bright green marl, which, although dry at low water, and free from blocks of stone, is generally concealed from obser- vation by a thin layer of sand. Two hundred yards west of Nettlestone Point, thick beds of hard sandstone containing Limnea and large and small Palwdinu, and calcareous bands, sometimes formed of comminuted shells, which are the same beds as those seen further onwards beneath Priory (Summer-house) Point, appear on the shore forming a cliff, and support the path- way in front of the Crown Inn. Under the Flagstaff, the shelly limestone which constitutes the upper five feet of the bed is almost entirely made up of comminuted Melania crcarata, with bands of Paludina lenta the whole resting on flaggy siliceous grits contain- ing ripple-marks. The rocks at Nettlestone Point are thick- bedded concretionary limestones, in some places soft and conrposed of comminuted Paludina lenta, in others passing into hard siliceous grit. They constitute large blocks on the shore, eight feet thick, which weather very unequally into irregular cavities, and contain a few small rounded pebbles of flint, larger fragments of sub- angular flint, Turtle bones, and fossils with the shells preserved. The lower four feet become more indurated and cavernous (honey- combed) and pass into hard yrit; while in the freestone, about two feet six inches from the top, there is a well-defined band of Limnea, six inches in thickness. Green sand, with large flat len- ticular concretions of a yellow colour, which have an irrecular surface and resemble septaria, overlies the limestone. e : Round the Point, the upper part of the thick grit becomes an indurated marl of an ochreous colour, with greenish-grey, argillo- caleareous concretions; while further east, a short distance west of the boat-house, it becomes a limestone (containing Chara and Limnea longiseata), which has been quarried on the shore for OSBORNE BEDs. 155 building stone. This change of mineral character apparently escaped the notice of Professor Forbes, who has described the bed, both under its normal and altered aspect, in his section of the Nettlestone Gnit, at pages 74 and 75 of his memoir on the Fluvio- marine formation of the Isle of Wight, as two distinct and separate strata, Nos. 9 and 10. The following is Forbes’ detailed section of the beds in the centre of this anticline :— (1. St. HeLen’s Sanps.) 1. Immediately under the lowest bed of the Bembridge Lime- stone (here divided into three bands) occurs a band of dark greenish carb naceous clay, breaking with a sub-conchoidal fracture, and forming a truncated stratuin in the cliff; 1 fi. 6 in. 2, Pale greenish white and yellowish mar]s, with patches of caleareous sand and comminuted shells; also argillo-calcareous nodules of various sizes. In this bed a characteristic fossil, Melania excarutu, occurs in abundance, and has the shell preserved. 8 ft. 3. Pale green, yellowish, and white sands, hardening into sand- stones, with large lenticular siliceous concretions and spongoid bodies. Melania excarata is plentiful here and there, and occasionally occurs crowded. A small Hydrobiu is also present ; and from a mass of loose sand I extracted a Helix with the shell entire, apparently Helix omphalus, but unfortunately destroyed the specimen. 14 ft. 4, Greenish-yellow irregular and concretionary sandstone, with siphonoid or fucoidal bodies ; 3 ft. 5. Yellowish and whitish sands, with a line of purple (manga- nese ?) nodules and siliceous concretions below; 9 ft. 6. Laminated white sands, indurated into quartzose flags above and helow ; the upper surface exhibiting strong current marks. This band is remarkable for its contents, including Zimnea longiscata, a shorter species of Limnea, resembling L. peregra, Planorbis obtusus, and Melania exeavata, ail in the condition of casts. The fossiliferous portion is in the lower part. 3 ft. 7. White sandy clay, with a band of broken Cyrene ; 2 ft. 8. Greenish-blue clay, seen on shore at low-water, containing Cypride and traces of Melunia and Cyrene (C. obovata?), The thickness may be estimated at 8 ft. [This apparently contains the fish-bed discovered by Mr. Colenutt.] (2. NETTLESTONE GRITS.) 9. Imperfect softish bright yellow limestone, riddled by minute confervoidal cavities, hardening into a building stone by exposure 156 GEOLOGY OF THE [SLE OF WIGHT. to the weather. Not.very fossiliferous, but contained Limnea longiseata, a large full-bodied species, Hydrobie, and Chara nucules (Chara Lycllii). This limestone may be seen opposite the boathouse near Nettlestone, but as it is much carried away is not evident except at a low water. It is the equivalent of the band in the slope at Whitecliff Bay. 2 ft. 1). Bright yellow and white marly clays, with patches of ereenish sand, filled with argillo-calcareous nodules of various sizes. In these nodules the Melania cxcaruta abounds. These clays do not appear to exceed a thickness of 4 ft. 11. Freestone or rag, with siliceous concretions passing into a erit. A great part of this bed is made of comminuted univalves, the fragments smaller and finer below. In the middle portion secur bands of unbroken Paludina lentu. This is the bed of which portions are thrown up in the line of the fault below Summerhouse Point, where it is very conglomeratic and includes pebbles of flint. Similar pebbles are seen here and there in it at Seafield. Itis used for a building stone there, and for making the groins on the shore east of Ryde. In these beds the casts of Melania excavate occur in myriads, also Pauludiny lenta, Hydrohie, a short AMelanopsis apparently AL breris, Mclunopsis carinata, Planorbis rotundatus (searce), Linnea longiscata, and the short- spired species, vertebree of fish, and fragments of turtle. 8 ft. In a block in a neighbouring wall I observed impressions of a small and peculiar Ccrithium, and remains of a large shell, apparently Achatina costelluta, 12. Softer and whiter sandstone, with frequent calcareous con- eretionary bands. containing Linnea lougiscata, and separated by a thin layer of compact sandstone with impressions of Unio, form a compact flagstone with fucoidal impressions. 4 ft. 13. Shelly sandstones, often studded with angular flints; 6 in. 14. Soft calcareous stone, with Puludina lenta ; 6 in. 15. Flags of sandstone, with large ripple marks; 6 in.” At Sea-View the fish-bed occurs at the base of the cliff a short distance east of the Pier, and as the Nettlestone Grits sink beneath the sea-level close to the Pier, it is probable that the fish- bed is in the clay at the base of Forbes’ higher division, or St. Helen’s Sands. At this locality, as near Ryde House, ripple- marked flags are found immediatly above it. At Priory (or Horestone) Point, thick-bedded sandstone (No. 11 of Professor Forbes’ Nettlestone section) forms the base of the cliff, containing in some parts bands of small rounded flint pebbles; in others, layers of partially decomposed angular flints, The upper part is full of broken shells, and patches of comminuted shells occur about two feet from the top, which is calcareous, and less hard than the lower portion of the bed. There are also occasional fucoidal markings and large irregular concretions which, weathering unequally, cause the rock to assume a honey- combed cavernous appearance. OSBORNE BEDS. 157 A fault at the Point, running in a direction 30° E. of S., skirts the shore and brings up the Nettlestone division of the Osborne Beds, in a manner that at first sight appears to be very puzzling, Nothing more is seen of the Osborne strata between Watch House Point and Whitecliff Bay. The strata composing the Osborne series were better displayed at Whitecliff Bay in the summer of 1856 than at the time of Professor Forbes’s visit, when they were concealed by landslips, or in grass-covered undercliffs. The following is a list of the beds then observed :— Section of the Osborne Beds in I hitecliff Bay, Prer. Dark bituminous clay, with Limnea in patches : Grit - - Dark olive-green clayey sand - - - > 3 Red and green mottled clays, with 1 to 2 inches of clay iron- stone on the top of the bed - - 18 or 20 Green clays - - - - 3 or 4 Dark grey sandy clays - - os 3 Shelly band, large Paludinu, Melanopsis carinata : 43 Dark green marls - a 8 Olive-green clay, Melanopsis carinata, Paludina lenta - # 15 to 18 Fine cream-yellow limestone, running out to sea in a direction 10° N. of E. No fossils observed 1 Green clays; Paludina, Melanopsis - About 15 Total thickness of Osborne beds - ei 792 The foregoing sections will show how uncert iin and difficult to fix is the boundary between the Headon and the Osborne Series, When one examives the fossils also, not a single mollnse can be found that is confined to the Osborne Beds, and the only peculiar fossils are small and delicate fish and prawns, the preservation of which is due to exceptional circumstances In fact, so little is yet known of the fauna of the Osborne Series, that it still remains doubtful whether these beds ought or ought not to be separated from the Headon. ; . The paucity of species seems to be mainly due to the conditions under which the beds were deposited. ‘here is an absence of truly marine beds, though a few marine shells occur. Purely freshwater strata are also rare. The mass of the clays seems to have been deposited in lagoons, varying in saltness, in which could live brackish-water molluses like MJelania and Potumomya, and a few of the more hardy freshwater and marine species. Lagoons of this character are at the present day favourite places for turtles and alligators, like those so abundant in this deposit. No doubt the Osborne Beds have been undeservedly neglected, owing to their proximity to the much more interesting Headon and Bembridge series. But the fish-bed, especially, is well worth further examination and tracing into other parts of the Island. 158 GEOLOGY OF THE ISLE OF WIGIIT. Not only is this horizon noticeable for the occurrence in it of shoals of small fish and prawns, but the abundance of scales and vertebre of the ganoid Lepidosteus is of great interest. A bed which yields such well- -preserved fish and prawuis is likely also to contain plant-remuins and insects. A few plants have already been obtained from it near Ryde. During a recent visit to Cliff End numerous well-preserved plants were discovered on this horizon (by Clement Reidand Henry Keeping). No attempt was then made at systematic collecting, but durimg an hour or two’s search grass or sedge-like leaves of several venera, palm ?, fern, and fragments of several peculiar reticulated leaves were found. This locality would repay more minute examination, as scarcely anything is yet known about the botany of the Osborne period. BEMBRIDGE LIMESTONE. Of the Fluvio-marine strata of the Isle of Wight, the Bem- bridge Group is by far the most constant in lithological characters, and the changes exhibited by its component strata throughout their range are for the most part slight and unimportant, It is consequently everywhere easily recognizable by mineral com- position, and, as might be expected, its most characteristic fossil contents are, in the 1 main, very uniformly distributed. Its lower portion is most calcareous, and everywhere in the Island exhibits more or less compact limestones, occasionally separated by shales, and accompanied by marly beds. These limestones in the first edition of the Map and Memoir were treated merely as part of the Bembridge Series. But it has been found easy to separate them on the more accurate topographical map now available, for they form the most marked feature to be seen in any bed above the Chalk in the Island. There is also in places a distinct line of erosion between them and the overlying marls, and everywhere proof may be found of a sudden break and change in the conditions of sedimentation, from an almost purely ealearenue freshwater deposit, to amarine clay or sand. As there is an equally sharp line at the base of the limestone, where it rests on the mottled clays of the Osborne Series, the Bembridge Limestone is here treated as a separate subdivision, not necessarily differing greatly in age from the older or newer deposits, but showing a marked change of physical conditions at the time of its formation. The Bembridge Limestone includes the uppermost limestones of Headon Hill and Sconce, and the well-known limestones of Ham- stead and Gurnard Ledges, Cowes, and Binstead. On the same horizon lies the rock which, owing to a dip slope, spreads over so wide an area near Wellow and Newbridge. Headon Hill—TVhis miportant member of the Isle of Wight Tertiary series plays but an inconspicuous part in the Headon BEMBRIDGE BEDS. 159 section. Among the grassy slopes beneath the gravels that crown the summit of the Ill, white and yellowish sandy marls appear here and there in the broken ground, occasionally varied by con- taining hard white compact limestone nodules that break with a sharp- -edged, splintering fracture. A little to the north of the summit these beds, dipping northward, become rather more de- veloped, passing into concretionary and travertinous limestones. The bodies regarded by Mr. Edwards as turtle’s egos occur among them ia regular lines. The fossils found in the con- eretions are almost inv: arlably terrestrial, and consist of Jelix D Urbani, H. omphalus, HH occlusa, H. headonensis? Bulimus ellipticus, Pupa perdentata, and Cyclotus cinctus. Bulimus ellipticus (Pig. 51), Helix Fia. 51. globosa (Fig. 52), Planorbis discus Bulimus ellipticus, Sow. (Fig. 53); &c., have been obtained from these beds by the fossil collectors of the Geological Survey, mostly in the condition of casts, but the shell is sometimes replaced by cale-spar, which also occurs in a crystalline form lining and filling small cavities in the stone. As a general rule, the Bembridge Limestone may be distinguished from the thick Upper Headon Limestones, as well as from those in the lower groups, by its greater whiteness and its peculiar brecciated or tufaceous character, as well as by the fossils either being casts, or having their shells replaced by cale-spar. The Headon Limestones, on the contrary, are of a somewhat darker cream- colour, more earthy and soft in com- position, and have the shells of the Limnee and other fossils preserved. ra, 52. The total thickness of this lime- ye stone at Headon Hill is from fifteen to sixteen feet. It is surmounted by a ereenish-grey mar] with Cyrena obovata having both valves in contact, which passes upwards into a soft, unctuous, earthy limestone, containmg Planorbis and a large Limnea, which again merges upward into very tenacious grey clay, weathering brown and black, and carbonaceous on the top. In thickness these deposits are variable, eyen within short distances, the limestone being sometimes as much as three fect, while the clay resting upon it varies from three to four- teen inches. In one place, however, where the three deposits formed 160 GEOLOGY OF THE ISLE OF WIGHT‘. but a single bed, the aggregate thickness was three feet six inches ; viz., clay six inches; limestone, one foot ten inches; and green marl, one foot two inches. Above the carbonaceous clay is a soft cream-coloured earthy limestone, also containing Limnea and Planorhis, The thickness of this upper limestone, which has apparently a denuded surface, varies considerably, but from 5 to 8 feet of it appear from beneath the white sands which form the lowest member of the gravel series constituting the summit of Headon Hill. In a section pointed out by Mr. Keeping, further north, the Bulimus limestone, uneven and irregular, is covered in places with brown and black carbonaceous clay, filling irregularities in its surface. The green clay with Cyrena above the thick limestone (here from one foot nine inches to four feet thick) contains a layer of Cyrene fifteen inches from the bottom of the bed, while the limestone, which (in addition to Zimnea and Planorbis) also contains Cyreu in the lower three inches, is only one foot thick. The clays above are irregular, and of variable thickness, but average about two feet, the lower six to nine inches of which is brown clay, becoming occasionally dark and carbonaceous towards the bottom, and dark grey carbonaceous clay six to fifteen inches, the upper six to nine inches of which frequently consist of lignite ; two or three inches of sand, with carbonaceous lamin, succeeded by green marl, complete the section. Hard thick beds are quarried at the eastern extremity of this outlier. Another outlier, over three-quarters of a mile long, covers the high ground upon which Hill Farm is built. A pit has been opened in it at the end of the lane running in a north-westerly direction from the farm. In the road to More Green casts of Limuea, Planorbis, and small Heli have been found. > D’Urbani - - - - - - 12 » occlusa - - - - - - - 4 » tropifera - - - - - - 1 » _ (or Paludina) earinata, [probably Paludina angulosa] 5 Clausilia striatula? (young) - - - - - 2 Planorbis obtusus - - - - - - 3 . discus a oligyratus (young) - - - - = 25 Limna longiscata, var. 95 slender var. small. 5 ? large bodied var. Cyclotus cinctus = - - = - 6 * nudus = = - - - sal Bulimus ellipticus, Achatina costellata, and Helix globosa, are all large conspicuous species. Paludina angulosa and Achatina costellata (ig, 54) are the shells especially sought Fria. 54, for by the native collectors; but good specimens Achatina With the shell preserved are rare. The blocks costellata, Sow, Which have fallen from the crest of the hill are crowded with specimens of Planorbis and Limnea, and oceasionally Helix, the most common being Helix D’ Urbani, H. occlusa, and FL. vectensis. The Bembridge Limestone of Sconce descends below the 50-foot contour at its eastern end, and the small outlier further east nearly touches the 25-foot line. Continuing the dip shown by these outliers, we observe that the limestone ought to plunge beneath the sea within a short distance. We accordingly find an isolated rock at a quarter of a mile from the shore off Norton. This is inown as Black Rock. It is only visible at ex- tremely low spring-tides, and we have not been able to examine it, but have been told that it consists of a hard freestone. BEMBRIDGE LIMESTONE. 168 The depth of the old channel of the Yar prevents the Lime- stone from being traced continuously to the east side. But near Yarmouth Gas Works it reappears on the foreshore, and was also well seen in the railway cutting close by. Crossing Thorley Brook it gradually spreads out, so as to occupy an extensive dip slope, such as one scarcely expects from so thin and soft a bed. In the neighbourhood of Wellow, Shalcombe, and Newbridge an area of nearly 3 square miles is covered by the Limestone, which forms a bold escarpment rising to a height of about 270 feet near Shalcombe. A dip of about 2° to the north-north- east causes the Limestone to pass beneath the Bembridge Marls near the Yarmouth and Newbridge high road. Notwithstanding this large spread not many sections are now open, for brick has taken the place of limestone as a building material, and chalk is preferred for agricultural purposes. One would have thought, however, that this limestone, with its greater quantity of phosphoric acid, would have made a better manure; we have not been able to learn the reason for the substitution of chalk, even on farms where the Bembridge Limestone would be cheaper. The stone was formerly extensively dug in pits near the escarpment, but these are all overgrown, the only remaining sections being near Newclose Farm, in Thorley Street, near Marshfield, in Wellow, and near Bank Cottage, Newbridge, where the outcrop becomes more narrow. None of these pits are of much interest, or show the upper or lower surtace of the stone, Other sections are seen in the old pits between Newbridge and Fullholding, and for nearly a mile the road runs along a ridge formed by the Limestone. From chy pe eastward the bed ding becomes vertical. The limestone, therefore, occupies a very small area at the surface. There seems also to be a tendency for it, like other thin limestones, entirely to disappear for a depth of several feet from the surface, where exposed to the solvent action of rain water. For these reasons it is often difficult to follow the outcrop; but limestone has been seen south of North Park Farm; north of Swainstone; at Great Park; for nearly three-quarters of a mile west of Gunville; and in an old quarry half-a-mile east of Gunville. Returning to the coast, we find the Bembridge Limestone to sink beneath the sea at Yarmouth,* to reappear on the northern side of the syncline with a west-north-west strike. The limestone of Hamstead Ledge consists of three beds, with other softer bands between, and contains numerous specimens of Limnea longiscata, Planorbis, Chara, &c. It can be traced nearly as far as the Newtown river, making a conspicuous feature, though the old cliff is now much overgrown. * Jn ancient charters it is called Eremuth (Worslcy). L 2 164 GEOLOGY OF THE ISLE OF WIGIT. On the east side of the Newtown river it appears above the Osborne Beds at the Brick Yard, but sinks when traced in a south-easterly direction, and is lost beneath the marsh of Spur Lake, to reappear in the bed of the stream near Porchfield for a quarter-of-a-mile. Continuing eastward along the coast, the Limestone in the cliff gradually falls till it spreads out on the shore, forming two ledges with an expanse of dark green marl between. Near Thorness Wood the stone is lost, and does not rise again for about a mile and a half. The section in the cliffs near Burnt Wood is of creat interest, for it is almost the only place in the Island where the Bem- bridge Limestone contains perfectly preserved shells and not merely casts. It also shows a dis- tinct line of erosion between the Limestone and the overlying marine base of the Bembridge Marls. (See Vig. 55.) The bottom block of Limestone (not seen in the cliff at this point, 2 vut exposed on the foreshore oppo- site) calls for no remark. Jt. is merely a freshwater limestone of’ the usual character, with casts of Limnea. Above it comes a mass of dark green somewhat mottled marl, the upper nm, Melania. litt near Porchjield. a globuloides. Cyrena, Mya, Cerithi with well-preserved shi the shells here is due to the stone being sealed up ma mass of im- pervious clay. The upper surface of the limestone is much broken up and eroded, and in the cracks are found marine shells, Panopea (or Mya) minor having the valves united. In some places the erosion has cut en- tirely through the upper block of the Limestone, so that the base of the Bembridge Marls rests directly on the green marl withPaludina globulvides, In Thorness Bay the Limestone rises again, showine the same three divisions. The bottom block forms Gurnard Ledge, and A s part of which is erowded with perfect SS = specimens of the minute Paludina ss ec: 222 globuloides. On this lies the top 0 SS Il 82S block of Limestone; a soft earthy g Ss S22 stone, easily cut when first due out, ae = ~E but hardening by exposure. This x = = stone is full of uninjured specimens aes a of Limnea pyramidalis, L, miata, iS R 3 and Planorbis obtusus, but only for a ® & short distance. The preservation of ee % = L B. Bembridge Limestone —u S Black Clay, with Ostrea, Modiola C. BEMBRIDGE LIMESTONE. 165 the thin upper block makes a minor ledge nearly opposite Sticelett Farm. From (iurnard Ledge the Limestone runs as a marked feature in the cliff as far as Gurnard Bridge, but on the east side of the marsh the scetions are obscure and hidden by talus, though abundance of tallen blocks can be examined as far as Keypt Point. From this Point eastward through West Cowes another marked feature, now vvergrown or hidden by buildings, shows the outerop of the Limestone, which was formerly seen in the foundations of several of the houses. Near the West Cowes Gas Works the same rock is again met with, and from this point to Bottom Copse, where it sinks beneath the Medina, there is no difficulty in following its characteristic feature. Crossing the Medina, the Limestone is seen on the foreshore exactly opposite the point on the west bank where it was lost, thus proving that here the beds are continuous across the river and are not displaced by any fault. On the feature that marks the outcrop towards East Cowes a large abandoned quarry may be seen in Little Shambler’s Copse. The stone has also been quarried near East Cowes Park, in places now occupied by houses, and it is again seen at Elm Cottage, close to the south-western corner of the grounds belonging to Norris Castle. Here, at a height of about 120 feet, it is lost under the Plateau Gravel. At Newport the Limestone, though masked by Drift and rainwash, has been proved in several wells (see Appendix). Unfortunately the well at Mew’s Brewery—the only one that passed through the stone—was bored many years since, and the samples that have been preserved do not show the thickness of this bed. East of Newport the stone was formerly quarried about 200 yards north-east of Great Pan Farm; and again nearly due north of Little Pan Farm. It was also touched in a trial boring at Durton Farm. From this point it is lost for about a mile, owing to a covering of Gravel and wash from the Downs. Close to Combley Farm it re-appears, and can then be traced continuously, either by feature or by blocks ploughed up, as far as Little Duxmore, where it is vertical. East of the last locality the Limestone cannot now be seen for about 3 miles, though blocks were formerly ploughed up near Ashey. During the original survey, a section was also seen south of Little Nunwell, in a ditch under a newly-made fence. At Brading, where the dip becomes lower, the Limestone forms a more marked feature which passes under the Church. Wall Lane is also carried along the ridge; the stone having formerly been dug close to the road on the south side, there is now a vertical wall of rock running parallel with the lane. At the Cement Works the dip in the quarry is 5° at the northern borndary, but it increases to 10° close to the road, and to about 166 GEOLOGY OF THE ISLE OF WIGILT. 20° on the south side of the road. The flexure is as sharp as in Whitechif Bay. Wast of the Yar and Brading Harbour, the Limestone reappears at two spots at the edge of the marsh, and from Peacock Hill custward to Whitecliff Bay it forms a marked ridge. At Oshorne, the Limestone, which is lost under the Plateau Gravel, ought to reappear in the upper part of the Pier Wood, hut the grounds are so well planted, and the features so obseured by rainwash, that no trace of it is met with till King’s Quay is reached. flere, though the beds cannot he measured, part can be seen on the foreshore, and fallen blocks are abundant. [rom King’s Quay to Wootton Creek and Binstead, there is no difficulty in following the limestone-feature through the woods and tumbled ground, but there are now no open sections, even at Binstead, for the celebrated stone quarries are all worked out or abandoned, The Binstead quarries are so celebrated that the following notes, taken from the first edition of this Memoir, may be acceptable, though the sections cannot now be examined. “Jn a quarry in the wood west of Binstead Church, and opening to the sea, the upper part consists of thick-bedded, nodular, shelly limestone, with Bulimus ellipticus, Limnea, Planorhis (ike rotun- datus), Cyrena, or Cyclas, vesting on soft sandstones, and hard, calcareous, flagey beds, sometimes well-laminated, and containing teeth of duoplother/umn, claws of Lobster, Paludinw orbicularis, P. (small sp.), Lounea, and a small Planorhis, The upper part of the quarry is made up of green marls, and an irregular surface of Limnean limestone, which is covered with from one to four feet of ferruginous loam, almost free from flints. There are, however, a few small scattered flints in the loam, generally in the lower part, which is clayey, while in the upper half are lines of small fragments of limestone, with an occasional pebble. Under the rubbish, in the quarries between this and the road to Ryde, con- cretionary shelly limestone rests on sandy beds, with layers of clay, beneath which are four feet and a half of grey, flaggy sandstone, forming the bottom of the quarry, The Binstead limestone was formerly highly esteemed aga building stone, and has been used in the construction of several churches in Sussex, the interior of Winchester Cathedral, Lewes Priory, Yarmouth Castle and Quarr Abbey (I. W.), an old Saxon ruin at Southampton, noticed by Webster, &c., &c.”* In Ryde, according to Mr, Barrow, the Bembridge Limestone was met with in laying down some drains in George Street. It * The quarrics near Quarr Abbey were in estimation for many centuries. They furnished some of the stone for building Winchester Cathedral, as appears by a grant made by the Conqueror (and confirmed by William Rufus) to Bishop Waikelyne, and by two precepts from Henry I. to Richard de Redvers, Lord of the Island, for stone to be dug there for the Cathedral at Winchester ; and subscquently to Stieand when he transferred his See from Selsey to Chichester. The registers of Winchester aie William of Wykeham used this stone in building the body of Winchester athedral. BEMBRIDGE LIMESTONE. 167 is now visible near St. John’s Road Station, at a height. of about 15 feet above the sea, but it soon sinks beneath the marsh level, and is altogether Jost halla mile further south. The dip at Ryde is southward, but the amount is only about half a degree. At the west corner of Apley Wood, about 200 yards south of the sea-wall, an earthy limestone of the ordinary Bembridge type has been quarried beneath the site of some unfinished houses. This was probably the lowest bed of the Bembridge Limestone, but the place is now covered with underwood. The blocks were from fifteen to eighteen inches thick, and contained Linnea, Chara, &e. From this point the Limestone is invisible for more than a mile, reappearing in the road, and in a small pit about a quarter of a mile south of Sea View. At Horestone Point the Limestone again makes a distinct feature, traceable through the tumbled cliff as far as Watch House, or Node’s Point, where we again meet with clear sections. The dip is south-south-west. On the south side of Watch House Point the following section was measured :— Bembridge Limestone at Watch House Point: Fr. In. Limestone, irregular, marly, and most compact in the lower half of the bed, which is, also, the least fossiliferous. Full of Chara, with a few Limnea and Paludina globuloides. The upper 2 feet more ferruginous and less indurated, and is frequently marked by the abundance of Limnea - = - 2 Ss 4 0 Dark laminated clay ; the lower part of a lighter colour, and more sandy - - - - - - - - 1 3 Compact greenish clay (slightly bituminous), with fragments of Cyrena, and now and then a perfect valve - - - 9. Earthy limestone ; the upper part soft and of variable thickness. Planorbis discus in the upper part, Limnea throughout 1 Gto2 0 Hard green marl, with concretions in the lower part - - 2. 6 At St. Helen’s the Bembridge Limestone passes into the sea close to the old church tower, and reappears at Bembridge Point, The upper bed has an uneven, undulating surface, and is covered with a cap, of variable thickness, containing Oysters throughout its entire depth. From Bembridge Point to the Foreland the Limestone becomes nearly horizontal, spreading out to form extensive ledges on the foreshore, but not rising above high-water level till Whitecliff Bay is reached. Between Foreland Point and the margin of the bay it forms in great part the floor of the shore, with a hollow and slightly basin-shaped curve, dipping inwards and landwards on the east and south-east. The extension of the broken margin of this shallow trough constitutes the reef of rocks known as Bembridge Ledge, and formerly quarried at low water for building stone. Rolled fragments of the Limestone strew the bay, and mingle with the flint gravel of the drift to form the shingle. At a distance it is conspicuous among the neighbouring 168 GEOLOGY OF THE ISLE OF WIGHT. strata, owing to its general creamy-white hue, and the angular fracture of its leds. When closely inspected it is found to consist of a number of distinct strata varying somewhat in thick- ness in different parts of the bay, and yielding different measure- ments to observers in different yews, owing to the occasional swelling out of the individual beds. Their mutual relations and distinctions seem, however, to he tolerably constant at this locality. In the cliff, not far from the hotel, the Limestone rises from the shore with a rapid and sudden curve; its uppermost portion inclining ata high angle. The best point for examination will be found where the great curve of the limestones first reaches the shore, and where these strata are exhibited in their entirety with perfect clearness. Here this division of the Bembridge group is composed of the following elements :— Bembridge Limestone at Whitecliff Bay (Measured in 1856 by Professors Ramsay and Morris and H. W. Bristow). FEET. Hard white crumbly marl, with a few concretions and scattered shells, and becoming harder and more shelly for the lower 6 inches. Throws out water at the top. Planorbis discus, Limnea in places. Passes gradually into the bed below. This is No. 6. of Professor Forbes’ section (see below) 2 Hard, compact, :ery shelly limestone, sometimes forming two beds, with a harder and darker-coloured parting between. Chara tnberculata and Ch. sp.—very abundant. Paludina orbicularis at thet 2 feet from the top. Limnea, Planorbis discus, Planorbis 5 Hard bed of compact sandy limestone, weathering white; p/ant- like markings. Limnea (a few); Paludina (sm. sp.) - : 1 Dark grey and carbonaceous clays, laminated with sand in the lower part; light green in the upper 2 feet, where they are compact and marly, and separated from the lower 12 inches by a band of Cyrena obtusa with both valves joined - - 3 Cream-coloured cavernous limestone, with a hard brecciated con- cretionary cap, 6 to 4 inches thick, on the top of the bed, which weathers to a very irregular surface. Limnea, numerous Taxites and Planorbis (sm. sp.), Chara tuberculata, especially 2 feet from the top. Emits a bituminous odour when struck. 4 to 6 Soft, white, earthy limestone, with a few casts of shells; Planorbis, Limnea, Fish - 2 Concretionary cream-coloured limestone, with an uneven surface above and below; weathering irregularly, and emitting a bitu- minous odour when struck. Chara, Limnea longiscata - - 4or5 Another section mearured in 1853, near the same spot, by Professor Forbes and Mr, Bristow is interesting for comparison with the above, as it shows how the strata vary. Bembridge Limestone in Whitechiff Bay (1853). 6. Crumbly white marl, with small globular concretions. Chara tuberculata has its uppermost limit apparently in this bed. Planorbis obtusus is common in it, but, like all other shells in the Bembridge limestones, is almost always in the condition of a cast. 2 ft. 7 in. BEMBRIDGE LIMESTONE, 169 5. Greenish white limestone, very conerctionary and fossiliferous. Small patches of a white mineral are highly distinctive of this band. Linnea longiscata is the most abundant fossil. Of other shells I find in this locality Planorbis discus, P. rotundatus, P. Sowerbii, and P. obtusus, a new Paludina (identical with that in Wo. 1), Helia occlusa, H. labyrinthica, and two other species. The uppermost 6 inches are very conglomeratic. ‘This cap weathers pebbly, and contains freshwater shells; when removed by the action of the waters the stone below weathers with a rough and pinnacled surface, speckled by the white mineral and very shelly. ‘he substance of the bed is much less shelly below. The thickness at the margin of the bay is 4 ft. 3 in. 4. Pale, often white marly limestone, in some places becoming very compact ; remarkable for abounding in myriads of a small, rather globose Paludina (P. globuloides); containing also Limnea longiscata, a small Hydrobia, and, more rarely, Cyclostoma mumia, When this bed is much exposed supertficiaily it forms a flat white platform, with an undulated and much cracked surface, the cracks extending throughout its thickness. In its uppermost part is a paleish carbonaceous strip abounding in comminuted shells of Cyrene. ‘Lhe Chara tuberculata occurs in it. 3 ft. 3. Compact creamy yellow limestone, abounding in casts of Limnea longiscata, of which parts of it seem almost entirely made up; also Planorbis oligyratus 2 The nucules of Chara tuberculata occur in this bed, but not so plentifully as in No. 1. The uppermost portion of it is conglomeratic. 5 ft. 6 in. This is the bed most sought after here for building, yielding blocks of considerable dimensions. 2. Greenish grey marly clay, with an irregular and crumbling fracture ; it contains crushed shells of Limnea longiscata and Planorbides. 4 ft. 6 in. 1. Yellowish compact limestone, weathering rather darker, exhibiting in the fracture minute confervoid ramifying cavities. ‘This bed is very full of casts Limnea longiscata and nucules of Chara tuberculata are scattered abundantly through its substance. A small Paludina, a Hydrobia, and a Planorbis (oligyratus) occur occasionaliy. The average thickness is 3 ft. 6 in. Total thickness at Whitecliff Bay, as exposed in November 1853, 24 ft. 3 im. When measured near the same spot by Captain Ibbetson and Professor Forbes in 1854, it was made 27 feet. Professor Prestwich, in his section, states the thickness as 26 feet. The fauna of the Bembridge Limestone has been very carefully collected. As a rule it consists entirely of freshwater mollusca. In a few places, however, abundance of land shells have also been obtained, and in others, as at Headon Hill and Binstead, mammalian remains are not uncommon. The land shells comprise Fig. 56. tropical-looking gigantic species of Bulimus : he and