BOUGHT WITH THE INCOME FROM THE SAGE ENDOWMENT FUND THE GIFT OF ilcnrg W, Sage 1891 Um^K airmk Cornell University Library QE 262.H5J93 1908 The geology of the country around Henley 3 1924 004 542 076 Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924004542076 MEMOIRS OF THE GEOLOGICAL SDRYEY. ENGLAND AND WALES. EXPLANATION OP SHEET 254. THE GEOLOGY OF THE COUNTRY AEOUND HENLEY-ON-THAMES AND WALLINGFOED. BY A. J. JUKES-BKOWNE, B.A., F.G.S., AND H. J OSBORNE WHITE, F.G.S. PUBLISHED BT OBDEB OF THE LORDS C0MMI3SI0BERS OF BIB UAJESIY'S IBEASCBY, LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE BY WYMAN & SONS, LIMITED, FETTER LANE, E.C. And to be purchased from E. STANFORD, 12, 13, and 14, Long Aoeb, London; W. & A. K. JOHNSTON, Ltd., 2, St. Andrew Square, Edinbueoh; HODGES, FIGGIS & Co., Grafton Street, Dublin; From any Agent for the sale of Ordnance Survey Maps ; or through any Bookseller from the Ordnance Survey Office, Southampton. 1908, Price Two Shillings. LIST OF MAPS, SECTIONS, AND MEMOIRS OF THE GEOLOGICAL! SURVEY OF ENGLAND AND WALES, AND MUSEUM OF PRACTICAL GEOLOGY. J. J. H. Teall, M.A., D.Sc, F.B.S., Director of the Geological Survey and Museum, Jermyn Street, London, S.W The Ifaps and Mfmoirs are now issued by the Ordnance Survey. They can be obtained from Agents or direct from the Ordnance Survey Office, Southampton, Museum , Catalogues, Guides, &c., are sold at the Museum, 28, Jermyn Street, London. A Complete List of the Publications can be obtained from the Ordnance Survey Office, Southampton. Price Gd. INDEX MAP (25 Miles to the inch), Map of the British Islands. Price— Coloured, 2s., uncoloured, Is. GENERAL MAP (one inch to 4 miles). ENGLAND AND WALES.— Sheet 1 (Title) ; 2 (Northumberland, &c.) ; 3 (Index of Colours) ; 4 (I. of Man) ; 5 (Laki District) ; 6 (E. Yorkshire) ; 7 (North Wales) ; 8 (Central England) ; 9(Eastern Counties) ; 10 (South Wales and N. Devon)! 11 (\V. of England and S.E. Wales) ; 12 (London Basin and Weald) ; 13 (Coniwall, &c.) ; 14 (South Coast. Torquay to I. of Wight) ; 15 (S. Coast, Havant to Hastings). Sheet 1, 28. : sheets 2 to 15, 25. 6d. each. Printed in colours. NEW SERIES.— Drift, Sheet 8 (FLimborough and Grimsby), 2s. ; Sheet 12 (Peterborough, Norwich), 2s. id. Sheet 16 (Cam bridge, Colchester), 2s. 6ci. Sheets 20 and 24 (London, Dover and Brighton), 2s. 6(Z. 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MACCLESl'JBLD STOKE • UPON - TEENT LOUGHBOROUGH ATHEESTONE LEIi-ESTER HUNTINGDON BEDFORD AMMiNFOED MEETHYR TYDFIL ABEHGAYENNY Solid. .. d. 66 and 57 8 6 Drift. 8. d. 1 6 1 6 123. 141. 165. 166. 187. 203. 230. 231. 232. 246. 247. 248. 249. 254. WOK MS HEAD 16 SWANSEA PONTYPRIDD.. NEWPORT (MON.) HEKLBY-ON-THAMES 261 and 2f 2. BRIDGEND 263, CARDIFF aJid WORLE, SOJIER- SET 267. NEWBURY 268. READING 282. DEVIZES 283. ANDOVER 284. BASINGSTOKE 296. TAUNTON and BRIDGWATER 298. SALISBURY 299. WINCHESTER " 300. NEW ALRESFORD .. 311. ■\\ ELLINGTON and CHARD Solid, s. d. 814. 315. 316. 317. 325. 826 329. 330. RINriWOOD SOUTHAMPTON HAVANT CmCIIESTEBr EXETER and 340. SIDMOUTH and LYME REGIS .. DORCHESTER .. BOUENKMOUTH, WIMBOENE . Parts NEW FOREST and I. OF WIGHT.. Drift! s. 1 1 1 1 331. POinsMDUTH and part of ISLE OF \\IGHT(Drift, Colour printed) 8 ISLE OF WIGHT (lu one Sheet) . . 332. I'.DGNOK, Ac; 1 333. AVORTflING, ROTTINGDEAN 334. NEU'HAVBN, EASTBOURNE 339. NEWTON A PBOT 341. WEST FLEET 842. PORTLAND, WEYMOUTH 843. SWANAGE, CORFE CASTLE 346. NEWQUAY 348. PLYMOUTH 349. PLYMOUTH and I VYBRIDGB 860. TORQUAY 361 and 363. LAND'S END DISTRICT .. 362. FALMOUTH * TRURO 863. MEVAlilSSEY .. 366. KIXGSIiEIDGK 886. START POINT 367 and 360. ISLES OF SCILLY.. MAPS (six-inch). The Coalfields and other mineral districts of the N. of England (the N. Staffordshire and S. Wales) Coalfields, and Leioesterl shn-e and Deibyshn-e, are m part published on a scale of six inches to a mile. MS. (•..I.inrnl Copies of other six-inch mansj not iTiteu-led tor publication, are deposited for reference in the Geological Survey Office, Jermyn Street, Loudon and conii can be supplied at the cost of drawing and colouring the same, , " up =», HORIZONTAL SECTIONS. VERTICAL SECTIONS. 1 to 140, 146 to 148, price 6s. each. 1 to 86, price 3s. U. each. MEMOIRS OF THE GEOLOGICAL SURVEY. ENGLAND AND WALES. EXPLANATION OF SHEET 254. THE GEOLOGY OF THE COUNTRY AEOUND HENLEY-ON-THAME^. AND WALLINGFORD. BY A. J. JUKES-BROWNE, B.A., F.G.S., AND H. J OSBORNE WHITE, F.G.S. PUBLISHED BT ORDER OF TBE LORDS OOMMISBIOHERB OF HIS MAJESTY'S TRBA9URT, LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE BY WYMAN & SONS, LIMITED, FETTER LANE, E.C. And to be purchased from E. STANFORD, 12, 13, and 14, Long Acke, London ; W. ife A. K. JOHNSTON, Ltd., 2] St. Andrew Squaee, Edinburgh; HODGES, FIGGIS & Co., Grafton Street, Dublin; From any Agent for the sale of Ordnance Survey Maps j or through any Bookseller from the Ordnance Survey Office, Southampton. 1908. Price Two Shillings. PREFACE. The original geological survey of the area was made on the old series one-inch maps, and~^ubUshed on Sheets 7 and 13 (without drift) in 1861 and 1859, by E. Hull, H. Bauerman and W. Whitaker, and on Sheet 7 (with drift) in 1871, by H. B. Woodward, J. H. Blake and F. J. Bennett. ' The area" was re-surveyed on the six-inch scale by the late J. H. Blake and Mr. A. J. Jukes- Browne, and published on the new series one-inch map, Sheet 254, in 1905. The_ geology of the area has been described in the separate memoirs on Sheets 7 and 13, in the larger memoirs on the Geology of the London Basin and Geology of London by Mr. Whitaker, and in the Memoir on the Cretaceous Rocks of Britain, by Mr. Jukes-Browne. The north-western portion of the area has been more recently described in the explanatory memoir accompanying the Special Oxford Sheet, and some modifications in the grouping of the strata (as- noted on p. 7), have been made on that map. The area includes a considerable portion of the Chiltern Hills, and part of the Thames Valley. The superficial deposits and their relation to the scenery have perhaps attracted most attention from geologists, from the days of BucMand and Conybeare, to those of Prestwich, who has been followed by Messrs. R, S. Herries, H. W. Monckton A. E. Salter, 0. A. Shrubsole, Osborne White, and others. The Cretaceous chapters of the present memoir were written by Mr. .Jukes-Browne, prior to his retirement from the Geological Survey; and his' observations on the zonal divisions in the Chalk have been supplemented by thoSe of Mr. Osborne White and Mr. Llewelyn Treacher. Short notes on the Jurassic and Lower Cretaceous formations are contributed by Mr, H. B. Woodward, and Mr. G. W. Lamplugh. For the chapters on the Eocene and superficial deposits we are indebted to Mr. Osborne White, who has incorporated notes made by the late J. H. Blake. Mr. H. H. Thomas has contributed some notes on rock- specimens, and we are indebted to Mr. A. S. Kennard for identifying specimens of mollusca from the Alluvial deposits. J. J. H. TEALL, Director. Geological Survey Office, 28, Jermyn Street. London. 5 August, 1908. 10322, ."inO.—Wt. 29091/ 9/08.-Wy. & S IV NOTE. The following is a list of the six-inch Geological Maps included in the area, of which MS. coloured copies are deposited for public reference in the Library of the Geological Survey and Museum of Practical Geology : — BERKSHIRE. 15 N.E. Didcot. By A. J. Jukes-BroM'ne, 1886 15 S.E. East Hagbourne. „ 1886 16 S.W. N. & S. Moreton. 1886 21 n;.e. Blewbuiy. 1887 21 S.E. Aston Upthorpe Downs. By A. J. Jukes-Browne and F. J. Bennett, 1885-87 23 (Bucks. 51, Oxfordshire 54) Henley-on-Thames By J. H. Blake, 1896 OXFORDSHIRE. 39 S.E. (Berks. 6S.E.)N. of Radley. By J. H. Blake,- 1899, and T. I. Pocook, 1905 40 S.W. Toot Baldon. By J. H. Blake, 1899, and H. B. Woodward, 1907 40 S.E. Hangman's Bridge, By J. H. Blake 41 S.W. N. Wheataeld Park. 41 S.E. Postoombe. 42 S.W. (Bucks. 37 S.W. ) Chinnor Hill. 45 N.E. (Berks. 10 N.E.) Nuneham Courtenay. 45 S.E. (Berks. 10 S.E.) Clifton Hampden 46 N.W. Chislehampton 46 N.E. Chalgrove, Ascot. 46 S.W. (Berks. 11 S.W.) Dorchester. 46 S.E. Berrick Salome. 47 N.W. Stoke Talmage. 47 S.W. Watlington. 49 N.W. (Berks. 16 N.W.) Bi-ightwell. 49 N.E. ( ^, 16N.E.)Ewelme. 49 S.E'. ( „ 16 S.E.) WallLngford. 30 N.W. Britwell Salome. By A. J. Jukes-Browne, 1885-86. By A. J. Jukes-Browne, 1887, and J. H. Blake By A. J. Jukes-Browne, J. H. Blake, 1897, T. I. Pocock, 1905, and H. B. Woodward, 1907 By A. J. Jukes-Browne, 1887, and J. H. Blake, 1897 By A. J. Jukes-Browne, 1887, J. H. Blake, 1899, and H. B. Woodward, 1907 By J. H. Blake, 1899 By A. J. Jukes-Browne, 1886, and J. H. Blake, 1899 By A. J. Jukes-Browne, 1886 By A. J. Jukes-Browne, 1886, and J. H. Blake, 1^9 By A. J. Jukes-Browne, 1886 1886 1886 1886 ., ,, 1886 50 S.W. Nuffield. By A. J. Jukes-Browne, 1886, and J. H. Blake 0-2 N.W. (Berk.s. 22 N.W.) Moulsford By A. J. Jukes-Browne, 1886. 52 N.E. ( ,, 22 N.E.) Ipsden. J) )j 1886. 52 S.W. ( „ 22 S.W.) Goring. By A. J. Jukes-Browne and J. H. Blake, 1891 52 S.E. Woodoote. JBy J. H. Blake, 1889 63 (Bucks. 50) Stoke Row, Net- tlebed. 1896 BUCKINGHAMSHIRE. 37 S.E. N. of Saunderton Lee. By A. J. Jukes-Browne, and J. H. Blake 1885 40 N.E. (Oxford 47 N.E.) Aston By A. J. Jukes-Browne, 1886, Rowant. and J. H. Blake 40 S.E. (Oxford 47 S.E.) Shirburn By A. J. Jukes-Browne, 1886, Hill. and J. H. Blake, 1899 41 N.W. (Oxford 48 N.W.) Radnage. „ 1899 41 N.E. Saunderton Lee. By J. H. Blake 41 S.W. Stokenchurch. J) 41 s.e; Chawley Manor Farm. 3) 45 N.E. (Oxford 50 N.E.) Northend. 1891 45 S.E. ( „ 50 S.E.) Stonor Park 1890 46 N.W. Fingest, Cadniore End. 1900 46 N.E. Lane End. 1900 46 S.W. (Oxford 51 S.W.) Skirmett. 1900 46 S.E. Moor End. 1, 1900 CONTENTS. PAGE Preface by the Dieectoe iii Chaptee I.— Inteoduction 1 Chapter II.— Jurassic. Oxford Clay— Corallian— Kimeridge Clay— Portland Beds ... Chapter III. — Lower Cretaceous. Lower Greensand Chapter IV. -Upper Cretaceous. Selbornian — Gault and Upper Greensand 11 Chapter V. — Upper Cretaceous {continued). Lower Chalk 19 Chapter VI. — Upper Cretaceous (continued). Middle Chalk 29 Chapter VII. — Upper Cretaceous (continued). Upper Chalk -36 Chapter VIII.— Eocene. Heading Beds — London Clay 58 Chapter IX.— Scenery and Superficial Deposits. Pebble Gravel— Clay- with-Flints 77 Chapter X.— Superficial Deposits (continued). Plateau Gravel 84 Chapter XI.— Superficial Deposits (continued). Valley Gravel — Alluvium 93 Appendix. — Bibliography. List of Principal Works on the Geology of the District ... 104 Index 107 ILLUSTEATIONS. PAGE Fig. 1. — Map showing outcrop of the Chalk Kock north of Henley- on-Thames Frontispiece. Fig. 2.— Fault between Berrick Salome and Cuxham 22 Fig. 3. — Section from Swyncombe Downs to Brightwell Baldwin .. 23 Fig. 4.— View of a Quarry on Chinnor Hill 41 Fig. 5. — Section of Sand-pit on the south-east side of Lane End Church 63 Fig. 6. — Section across the Lane End Outlier 66 Fig. 7.— Sections in the Nettlebed Outlier 69 Fig. 8.— Diagrammatic view and section of the Thames Valley north of Henley-on-Thames 87 Fig. 9. — Section from Brightwell Baldwin to the River Thame near Drayton St. Leonard S9 Fig. 10. — Section at Turner's Court Gravel-pit, Wallingford ... 91 Fig. 11.— Fan of Chalky gravel at Greenlands, south-west of Hambleden 96 Fig. 12. — Section across the valley west of Harpsden 100 Fig. 13. — Section of Alluvium at Wallingford 102 Greys x asrTHAMEi •Oudh MidcOe ChaOs^XlEIIil^ SJujrt hloyck UnesincHcate exposurescfCfidlhRock Fig. 1 — Map Showing the, Outcrop of the Chalk Mock north of Henley-on-Thames. CHAPTER I. INTRODUCTION. By A. J. Jukes-Beowne. The area included within Sheet 254 of the Geological Survey- mar) is about 216 sc[uare miles. It comprises parts of Berkshire and Oxfordshire, with a small portion of Buckmghamshire. The chief towns are Henley, Wallingford, and Watlington, but in former days the Roman station of Dorocina (now Dorchester), and the British settlement on Sinodun Hill were places of importance. Physical Features. The area under description exhibits two very different types of scenery, all the western part of it consisting of low-lying land through which rivers and streams meander in sinuous courses, while the eastern part presents a network of hills and ridges separated by deep and generally dry valleys. These two areas are divided from one another by the slope which culminates in the long range of the Chiltern Hills, this range crossing the district from S.S.W. to N.N.E., and gradually increasing in height as it is followed from south to north. Thus east of Ipsden the highest point is 661 ft. ; at Nuffield the ground rises to 675 ft., on Brightwell Hill to 753 ft., and on Christmas Common east of Watlington to 790 feet. The Downs above Shirburn and Lewknor rise to heights of 825 and 837 ft., and Crowell Hill, near the northern border of the area, is 806 ft. The principal river is the Thames, a portion of which traverses the western part of the area, and after taking a southward bend appears again in the south-east corner of the map. The Thame, coming from the north* joins the Thames or Isis at Dorchester, and other small streams flowing outward from the foot of the Chiltern Hills pour their waters either into the Thame or the Thames above Streatley. The drainage from the eastern slopes of the Chiltern Hills is gathered into valleys, the chief of which open into the northerly bend of the Thames near Henley. Forirnations. The formations which enter into the structure of the district belong to four distinct geological systems ; these in descending order of superposition are — 4. The Pleistocene ; 3. The Eocene; 2. The Cretaceous ; 1. The Jurassic. Below is a tabular view of the subdivisions which have been made in these rock-groups, and are indicated by colours on the 10322. B INTRODUCTION. published geological map; the maximum thickness which each attains in the district is also given. Table of Geological Formations. Groups. Sub-divisions. Thickness in Feet. Recent and Pleistocene Lower Eocene Upper Cretaceous - Lower Cretaceous - Upper Jurassic Alluvium - Valley Gravel tlateau Gravel Pebble Gravel Clay-with-flints - London Clay Reading Beds Upper Chalk Middle Chalk Lower Chalk SelbornianjgPft'^^''^^^''!^"'^ Lower Greensand Portland Beds Kimeridge Clay - Corallian^ Oxford Clay^ 30 ■ 20 15 50 60 to 70 260 to 300 200 200 to 220 100 . 200 to 220 80 351 110 60 to 80 450 1 Not exposed at the surface. It should be mentioned that not one of these rock-groups is here complete, each being separated from that above by a break and unconformity. Thus between the Jurassic and Cretaceous series there is a gap represented in the south of England by the Purbeck Beds, the Wealden, and the older part of the Lower Greensand. Between Lower and Upper Cretaceous there is a smaller break. Between the Cretaceous and the Eocene is another gap, for the greater part of the Upper Chalk is wanting, as well the Thanet Sands at the base of the Eocene. Lastly, above the London Clay, all the rest of the Eocene and the Oligocene series is wanting. The physical features of the country are in great part due to the difference in the lithological composition of the rocks and to the manner in which the strata are arranged. These crop out to the surface in regular order ; the general dip of the beds being to the E.S.E., so that the strike or direction of out- crop crosses the area Irom S.S.W. to N.N.E. In consequence of this dip the lowest and oldest beds are found in the N.W. corner of the map, and anyone walking from that point in a South- easterly direction will come to and pass over beds that are successively higher in the geological scale. The existence of the Chiltern Hills is , another direct conse- quence of the dip of the strata, this range being part of the great escarpment of the chalk which runs across England, and its development is due to the greater resistance which the Chalk presents to detritive agents. The soft sands a,nd clays of the country to the west of it have been worn aiyay by the action INTRODTTCTIOX. 3 of rain and streams more rapidly than the substance of the Chalk ■which absorbs a large portion of the rain falling on its surface, and allows it to pass away underground. Some of this water is thrown out in springs on the outer slope of the escarpment, but much of it flows eastward under the London basin. The relation of towns and villages to the natural sources of water supply is well shown in the tract of country with which we are dealing. Almost all the village settlements in the western half of the area are situated either along the courses of the Thames and its tributary streams, or else near points where strong springs issue from the Chalk. Thus there is a succession of villages along the outcrop of the Lower Chalk, the sites of North Stoke, Mongewell, Crowmarsh, Ewelme, Britwell Salome, Cuxham, Watlington, Shirburn, Lewknor, Aston Rowant, and Crowell being all determined by the issue of springs which afforded a good supply of water. Within the line of the Chiltern HiUs villages are sometimes f)laced in the valleys and sometimes on the ridges, according as ocal conditions afforded some supply of water and local effort sunk wells in pursuit of it. Faults. Few faults exist in the area under description, and none oi them causes aiw great displacement. South of Moulsford, the outcrop of the Lower Chalk is terminated by a fault which strikes from west to east, and carries the Middle Chalk eastward to the alluvium of the Thames. Its throw is probably from 70 to 80 ft. Another and longer fault runs in a curving line from Berwick Prior through Cuxham and Pyrton to the neighbourhood of Lewknor. This brings the malmstone of the Upper Greensand against the Lower Chalk, but the displacement cannot be more than 40 or 50 ft. J0322. B 2 CHAPTER II. JURASSIC. By H. B. Woodward. Oxford Clay. This is the oldest formation proved to occur in the area. It consists mainly of clay and shale with occasional cement-stones or septaria ; but the lower portion, within 50 ft. of the base includes beds of sand and sandstone with, at the base, about 10 ft, of clay. These strata are grouped as the Kellaways Beds. The full thickness of the formation is about 450 ft. ; but it is nowhere exposed at the surface. Corallian. This is a variable group of limestones with clayey and sandy layers in the upper part, and of sand and sandstones in the lower. The total thickness may be as much as 80 ft., judging by a boring at Shillingford (see below). It is not exposed in the area. KiMERiDGE Clay. This formation is rather more than 100 ft. thick, and consists of dark shaly clay with earthy limestone nodules and septaria. The upper beds merge gradually into the Lower Portland Beds. Phosphatic nodules occur at the base, as noted in the following record of a boring. At ShiUingford, to the north of Wallingford in Berkshire, a boring was made in 1885 by Messrs. Isler and Company. The section has been described by Mr. Jukes-Browne, who records the strata as foUowsi : — Boring at Shillingford. Thickness. Depth. Ft. In. Ft. In. Soil, &c. - 4 Sand and gravel 15 19 Gault - 144 163 Lower Greensand - - ... 25 188 Kimeridge Stifif grey clay and stones (? septaria) 20 208 Clay. Black clay, with shells and stones, Ill ft. 6 in. I and phosphatic nodules at 296 ft. 91 6 299 6 'Eock - - . . Stony clay and shells (yellow gritty 12 9 312 3 Upper Corallian. < 44 ft. 6 in. loam) - • Kock, with some layers of clay- 5 9 8 11 317 327 11 10 Stony clay, with layers of rock- 8 ]0 336 8 ,Kock, with shell fragments {Ostrea)- 7 7 344 3 ' Sand and stone - Alternations of hard grey rock and clay Dark gritty clay and shells 7 4 351 7 Lower Corallian. - ^f^ ff *^ in 10 10 4 1 361 372 11 oo iL. o m. Hard grey limestone 2 6 374 6 , Sand and stone with water 5 379 6 Oxford Clay Blue clay, soft and slightly mottled - 4 G 384 1 Midland Naturalist, vol, xiv, p. 201. foli'fLANt) beOs. 5 The water obtained at the base of the CoraUian rose to within 60 ft. of the surface, and although palatable it did not yield a sufficient supply. Curiously enough that obtained from the Lower Greensand above was saline, containing 98 grains per gallon, 54 of which were chloride of sodium. At Culham, to the south-east of Abingdon, there is evidence of the presence of the passage-beds from Kimeridge Clay to Portland Beds, for John Phillips in 1860 noted the occurrence there of fossils like those of Hartwell, near Aylesbury. Portland Beds. The Portland Beds of the district consist of the following strata : — / Sand with, hard ferruginous bands. Upper J Whitish limestones. Portland Beds n Clays and greenish sands. l^ Glauconitic limestone with lydites. T ower f ^^^^ ^^^ brown clay with lydites, Portland Tieds \ Yellow and greenish-grey sands with concretionary 1 masses of sandstone. The upper beds yield the following fossils : — Lucina portlandica J. de C. Sow. Ostrea expansa J. Sow. Pecten lamellosus J. Sow. Trigonia gibbosa J. Sow. Perisphinctes boloniensis {de Lor:) Cerithium portlandicum J. C. Sow. Natica elegans /. de G. Sow. Cardium dissimile J. de C. Sow. Among fossils from the lower beds the following have been recorded : — Perisphinctes giganteus {J. Sow.) Perisphinctes pectinatus (Phill.) Lucina portlandica J. de G. Sow. Ostrea expansa J. Sow. Pecten nitescens Phill. Perna mytiloides Lam. Pholadomya rustica Ag. Pleuromya tellina Ag. Pinna. Trigonia pellati de Lor. The sands and limestones of the Portland Beds occur over a small area to the north-east of Stadhampton, and north-west of Warpsgrove ; but no noteworthy sections have been observed.' In his notes on the section at Culham brickyard to the south-west of Nuneham Courtenay, and beyond the limits of our map, Phillips described a bed of green sand, 9 ft. thick, below the Lower Greensand and Gault, and above the Kimeridge Clay, from which there were evidences of " an easy passage upwards from clay to sand." He obtained from this sand a few examples of the Ammonite like A. polyplocus, Gardiwn striatulum, Thracia depressa, Pecten arcuatus, Corbula, and wood ; and he suggested that the bed might be " perhaps the first stage of a change towards Port- land series." « At a later date, when the first Geological Survey was in progress, Prof. Hull found some fossils in " the road cutting at 1 General descriptions of the Jurassic Rocks, with lists of fossils, have been published in the Memoir on ' The Jurassic Rocks of Britain,' vol. v, ' Middle and Upper Oolitic Rocks of England (Yorkshire excepted),' by H. B. Woodward, 1895, pp. 167, 169, 217. 2 Quart. Journ. Geol. Son., xvi 1860 p. 310. 6 JURASSIC, Toot Baldon," north of March Baldon, and. of the area shown on the map. The discovery is thus mentioned I : — "At this place marine shells {Ammonites Deshayesii and Terebratula sella) of the Lower Greensand period were found, which are extremely valuable in determining the condition under which these beds were deposited." The late J. H. Blake, while mapping this area found some blocks of more or less cherty sandstone with casts of fossils, in a field 700 yds. east of March Baldon_ Green. , The fossils were poorly preserved, but they were examined in the Palseontological Department of the Survey by Mr. E. T. Newton, who reported that: " Although the specimens can scarcely be taken to prove the strata, to be of Lower Greensand age, yet their general facies points to this con- clusion." 2 It has been noted by Mr. Lamplugh that cherty beds are not known to occur elsewhere in the Lower Greensand of this district, and that cherty blocks since found on the slopes of Shotover Hill prove to be altered Portlandian rocks.* During his examination of the strata between Culham and Toot Baldon he had observed a change in the lithological character and colour of the beds northwards from the neigh- bourhood of March Baldon. There they consist of buff or greyish sands of finer grain than the coarse and pebbly Lower Greensand of Culham' and Clifton HampHen, and of great portion of Nuneham Park. Mr. Osborne White has likewise noted these differences. Meanwhile the Lower Cretaceous strata in this area had been described in 1898 as the "Toot Baldon Beds," by Dr. A. Morley Davies ; although he admitted the possibility that there might be a trace of the lower sandy beds of the Portlandian at Toot Baldon.* Durmg the early part of the year 1907 Dr. Davies very kindly sent to the Museum at Jermyn Street, for determination, some fossils which he had collected in 1903 from sandy strata in the lane-cutting south of Oldhouse Farm, Toot Baldon. The speci- mens include a claveUate form of Trigonia not sufficiently perfect to be identified specifically; also Cyprinal, 'JExogyra thwrinanni ? (Etallon), and Protocardia ? As the evidence supplied by these fossils was not regarded as conclusive, it was decided that Mr. .John Pringle should visit the area;^ and although he was unsuccessful at the locality where Mr. Davies 6btained his specimens, other fossils of identical matrix were obtained in the neighbourhood, some of them of similar species to those in the Lower Portland Beds at Shotover Hill, and preserved in rock of similar hthological character. Mr. Pringle 1 ' The Geology of Parts of Oxfordshire and Berkshire ' {Mem. Geol. Surv. ), 1861, p. 15. 2 'Summary of Progi'ess ' {Mem. Geol. Siirv.) for 1900, p. 120. The speci- mens refeiTed to are not preserved in the Survey collection. 3 The Cherty layers mentioned as ocoutj'ing in the Shotover Ii-on-sand and Ochre Series (see Phillips; Geol. Oxford, pp. 414, 415) were evidently at the base of the series and probably Portlandian. J'roc, Geol. Assoc, vol. xvi, p. 45. ' ' PORTLAND BEDS. 7 asoertainei that in the fields east of March Baldon and at Baldon Kow, highly fossiliferous " doggers " of sandstone are frequently met with at a depth of 6 to 8 ft. from the surface. He further noted that the sands with Portlandian fossils are fine grained and quite distinct from those of the Lower Green- sand ;_ thus confirming the suggestions made by Mr. Lamplugh. A line separating the Portland Beds and Lower Greensand has consequently been drawn in accordance with the evidence that couldbe gathered of the distribution of the different sandy deposits between the definite areas of Lower Greensand on the south, and of Portland Beds on the north. This line was inserted on the new Oxford map, but it was not shown on the map now under description, Sheet 254, which was previously printed. The following fossils were collected from the Portlandian Beds by Mr. Pringle :— Garden of house 440 yds. W.S.W. of St. Lawrence Church, Toot Baldon. [Pr. 3978-3984]. Astarte rugosa 1 (J. de G. Sow.) cf. Lucina portlandica J. de G. Sow. Corbicella ? Pecten cf. morini de Lor. Field 900 yds. N.E. of Post Office, March Baldon. [Pr. 3989-4000]. (Portlandian). Astarte rugosa {J. de G. Sow.) Pecten morini de Lor. Cyprina '! „ nitescens Phill. Leda?' ■ „ ■ sp. ' Ostrea sp. Perna sp. It should be mentioned that Mr. Pringle noted the strong resem,blanc8 of the sandy Portland bed seen at the southern end of the Culham pit, and previously mentioned, to the material composing the doggers of Portlandian sandstone met with at Toot Baldon ; and he obtained from the Culham sand-bed a doubtful Serf uld &ndi a specimen near to Isodonta longior (Blake;. I 1 These fossils [Pr. 4004-»4007] are preserved in the Museum at Jermyn Street, See also 'Geology of the Country around Oxford' {Mem. Oeol. Hurv.), 1908. In the Memoir on 'The Geology of the Country around Oxford' (1908), p. 51, raiments of an ammonite from Portland Beds at Shotover Hill were named Pensphinctes plicaiilU .» (J. Sow. ). These should not have been identified so nearly with this species, but should have been, merely recorded as '\ Ferisphinctes xp." r. L. K. CHAPTER III. LOWER CRETACEOUS. Lower Greensand. The following passages by Mr. G. W. Lamplugh are repro- duced from his description of a portion of the Lower Cretaceous rocks, in the Memoir on ' The Geology of the Country around Oxford; 1908 (pp. 77, 78) :— A broad tract of Lower Greensand was shown in the original Geological Survey map as covering Nuneham Park, and extending northward to Toot Baldon. In the new series map Sheet 254, which was colour-printed in 1905, Lower Green- sand was represented over the area of March Baldon to the northern margin of the map at Baldon Row, as surveyed by J. H. Blake. The mapping of this tract has been admitted, by all who have examined the ground, to present many difficulties, but as elsewhere noted (see p. 6), evidence has now been obtained to show that Portlandian beds occur over this part of the area, probably from the northern confines of Nuneham Park over the uplands of March Baldon and Toot Baldon, and eastwards towards Chislehampton. The evidence of fossils indicates conclusively that Lower Greensand occurs at Culham and Clifton Hampden to the south of Nuneham Park, and that Portlandian occurs at March Baldon, and also at Toot Baldon, just beyond the limits of our present area, on the north. The lithological evidence, as already pointed out, shows that the Lower Greensand locally consists of coarse and ferruginous pebbly and quartzose sand ; the Portlandian of fine-grained sands and sandstone. That the Lower Greensand is subject to rapid changes in thickness is shown in the brickyard section at Culham, where it is diminished to a few inches, though seen to a depth of 10 ft. in a sand-pit only 150 yds. farther west. In this sand-pit the strata consist of coarse gritty ferruginous sand with small pebbles, shown to a depth of 12 ft. ; and similar material, stiU more pebbly, is exposed in a low cliff on the Thames bank at Clifton Hampden. The beds in this region are locally indurated into rocky layers. In a MS. descriptive of the neighbourhood, written by Daniel Sharpe,! there is a statement that organic remains had been obtained from the sand " in a low bank by the side of the road which slopes from a turnpike in the Abingdon road down towards the ferry at Clifton : they are the following species in the state of ferruginous casts occasionally preserving the outer surface : — Exogyra conica, Terehratula ovata, EhynchoneUa octoplicata, 1 Preserved in the Library of the Geological Survey and Museum. LoWEK GREENSAjfb. .9 and Ithyn. Havipdeni, a new species found also in the Upper Greensand of Warminster." There is no doubt that these are marine deposits, as marine fossils have been found in the sandy layer between the Gault and the Kimeridge Clay in the Culham brickyard section. Phillips^ recorded a Pecten and an Exogyra from this bed ; and the present writer, in a brief examination of the pit, in the summer of 1902, found the casts of several shells, including a small oyster and a Troc/itts-like univalve. Mr. Jukes-Browne, however, considers the sandy bed of the brickyard to be the basement-bed of the Gault, which is sup- posed to cut out the Lower Greensand at this point ^- The mdurated portion of the sands in the adjacent sand-pit contain markings that appear to be the casts of fossils, and recently a large specimen of Eocogyra sinuata J. Sow has been found in a bed of coarse laminated sandstone at Culham.^ Some fossils have lately been collected for the Geological Survey, by Mr. J. Pringle, in the sand-pit west of Culham brickyard : they include the following : — Eadiopora sp. Exogyra sinuata J. Sow. cf. Venus orbigniana Forbes. G. W. L. The difference of opinion referred to in the foregoing para- graph, however, is more apparent than real, as the zone classed by Mr. Jukes-Browne as belonging to the base of the Gault is taken by Mr. Lamplugh to be the top bed of the Lower Green- sand. The zone in question — that of Douvilleiceras maramil- latum — is probably represented by the gritty band at the base of the Gault in the Culham section, as fossils recently obtained by Mr. Osborne White have indicated. (See p. 14.) J. H. Blake noted exposures of Lower Greensand north of Hill Farm and by Warren Farm, north of Culham ; also east- wards to the railway. These comprise pebbly sands of like character to the Lower Greensand before mentioned. By Rough Lodge, south-east of Nuneham Park, Blake, in 1896, recorded that a brickyard had been opened in 1852, and had since been abandoned. He noted 4 ft. of coarse quartzose sand resting on 4 ft. of thinly-bedded, coarse, ferruginous sandy rock, locally known as " Roach." Dark blue clay was said to have been dug, and clay also was said to have been obtained from Clifton Heath, where an outlier of Gault has been mapped. Coarse, pebbly and quartzose sand was observed by Blake in Lock Wood, on the western side of Nuneham Park. There the material known as " Roach " has been used for making paths. Similar sand was observed by him to the east and north- east of the Mansion in Nuneham Park. Here the diiSculties of 1 Qimrt. Joum. Geol. Soc, xvi (1860), p. 309 ; and ' Geology of Oxford,' p. 428. 2 ' The Cretaceous Rocks of Britain ' (Man. Geol Sun:) i, 1900, p. 268. See also H. J. O. White, P»w. Geol. Assoc, xviii, 1903, p. 300. 8 C. G. E. Dawkins, Geol. Mai/., 1906, p. 94. 10 LOWfift CRETACEOtTS. distinguishing Lower Greensand from Portlandian are compli- cated by the presence of patches of Drift sand and gravel, and the absence of good sections. H, B. W, . The following notes are by Mr. Jukes-Browne : — In the small riverside cliff at Clifton Hampden, the height of which is about 20 ft., the rock exposed, is a sandstone, consist- ing of coarse brown quartz sand, some of the grains being large enough to be called pebbles, but few are bigger than peas, the mass is bound together by a network of ferruginous veins or seams, and is very hard in the lower part, but the upper portion is disintegrated. The grains and pebbles are nearly all of quartz, but there are a few of a dull yellowish stone which is probably an indurated Jurassic rock (perhaps Corallian). At the brick-kilns on Clifton Heath near the south-east corner of Black Wood, pits, have been dug. to obtain sand for brickmaking purposes, and one of these exposed the following beds in 1887 :— Ft. In. Coarse pebbly sand or small gravel, like that of Clifden Hampden, but loose - - - 3 Passing down into coarse angular yellow and brown quartz sand 1 6 Pebbly sand like that above compacted by iron into a ferruginous rock -- -- - - 06 Coarse yellow sand passing down into fine sand, seen to - - - - ■ - 4 I was informed by the workmen that the fine yellow sand became grey below and harder ; a heap of such hard grey sand lay near the edge of the pit, and was said to have come from about 8 or 9 ft. below the ferruginous band. A. J. J.-B. 11 CHAPTER IV. UPPER CRETACEOUS. Selbornian (Gault and Upper Greensand). By a. J. Jukes-Beowne. The Selbornian, as indicated on p. 2, includes the Gault and Upper Greensand, and so long as these old names are used merely to designate special lithological facies of the formation there is no objection to their employment. As, however, in some localities the whole formation consists of clay and marl (Gault), while in others it is almost entirely composed of sand (Upper Greensand and Blackdown Beds), it is clear that a name for the group as a whole was wanted in order to prevent misconception. Moreover, there are large areas over which another kind of rock material forms a prominent member of the formation ; this is malm or m,ahnstone, a fine-grained sihceous rock, which cannot be properly called a sandstone, though the upper part of it often passes laterally into a fine micaceous sand or sandstone. Con- sequently it often happens that the Selbornian comprises three or four different kinds of rock- material in regular succession, and this is the case in Berkshire and Oxfordshire, where the succes- sion may be stated as follows : — Ft. In. Tinner Rreenaand ( ^K^*'°°^*^'= '^^''^ ^'^'^ ®^"'^" 20 ft. to 25 Upperljrreeusana|j^^jjjjg^.Q^g _ 50 ft. to 80 n„, ij- 5 Silty Marls - ) „„„ Gault- - 1 Grey clays - - - | 200 The clays and marls have l3een mapped by the Geological Survey as " Gault " and the beds above as " Upper Greensand," but the zonal arrangement of the beds is probably as follows : — ■ Zone of Pecten asper - - Glauoonitic marl and sand. Zone oi Schloenbachia rostrata | ^ft^^^^rk Zones of Hoplites lautus and ) ^ i //. interruptus - \ ^^^^ ''^^^^■ It should be mentioned, however^ that very Httle palffiontolo- gical evidence has been obtained in the area under description. The existence of malmstone in this part of England was first recognised in 1885, by Dr. G. J. Hinde.i It is a whitish rock, with very little true sand in its composition, consisting largely of sponge spicules and globular colloid silica, with some mica and a certain proportion of marly or calcareous matter. In some places it forms a massive grey rock, but more often there are alternating beds of compact malmstone and fine siliceous marl. 1 ' On Beds of Sponge Remains in the Lower and Upper Greensand of the South of England.' Phil. Trans., 1885, p. 416. 12 tJPPER CftE'fACEOtJS, West of Wallingford its thickness may be over SO I't., but it gradually thins eastward, becoming at the same time more and more interstratified with marl till near Chinnor its total thickness is probably not more than 40 ft. Fossils are not abundant in the malmstone, Hoplites auritus (J. Sow.), Aibcellina gryphceoides (J. de C. Sow.), and Fecten {SyTwyclonema) orbicularis J. Sow. being those most usually seen. The malmstone in its central part is a light grey sihceous and micaceous stone, which dries nearly white, and might then be mistaken for chalk when viewed from a Httle distance. Its specific gravity is small, and microscopical examination has proved that it is largely composed of organic silica derived from the dissolution of siliceous sponges.i Much of it is similar to the malmstone of Farnham, which Dr. Hinde describes as consisting almost entirely of organic siUca either in the shape of detached spicules or in the form of minute globules. He also examined specimens from WaUingford, which he thus describes: — " The rock is hard, and calcite is only occasionally present in it, but there is a greater relative amount of (juartz-sand and other mechanically derived constituents than m the malm of the Wealden district. The sponge-remains are either as empty casts or of amorphous silica, and the siliceous matrix is partly in the globular form " (op. cit, p. 416). Specimens from Cuxham, near V/atlington, which I sent to Dr. Hinde were found to be similar, and in -vvriting to me he says, " there are plenty of Foraminifera in all the specimens, principally Globigerina,, Textularia and Rotalia. In one of the specimens minute coccoliths are present." When a hand specimen of this malmstone is examined a number of glistening particles are seen, most of which are probably scales of mica, but some, as Mr. W. Hill has suggested to me, may be the broken ends of sponge spicules. The quartz- sand referred to by Dr. Hinde is in the condition of fine sUt, and is not visible to the eye ; minute grains of glauconite are also abundant in the rock. The above description applies only to the central portion of the malmstone mass, both the lower and upper parts becoming more earthy or marly, and containing a less proportion of organic silica. Above the malmstone a band of marl containing large grains of glauconite has been seen at several places, and is probably continuous for some distance. It may be from 6 to 9 ft. in thickness. The series is completed by an equally thin band of glauconitic sand, consisting entirely of quartz and glauconite grains, but no fossils have been found in these beds either near Wallingford or in Oxfordshire. 1 See Hinde, Phil. Trans., 1885, p. 403. GAULT. 13 Stratigraphiccd Details. Gault. The basset surface of the Gault in the area comprised within Sheet 254 is largely covered by gravel, and even in those tracts where it is at or near the surface there are very few exposures. At Didcot, just outside the western margin of the map, the uppermost marls are well exposed in the railway cutting near the station. At the bottom of this cutting there is tough micaceous marly clay which passes up into soft grey micaceous marl, containing Aucellina gryphceoides (J. de C. Sow.) ; small phosphatic nodules are scattered throughout the marls. In the old Geological Survey Map (Sheet 13) these marls were included in the Upper Greensand, and similar marls, with occasional floors of malmstone, are exposed in the first cutting on the Didcot and Newbury line. These are clearly the local passage beds from Upper Gault marls to the " Upper Greensand " or Malmstone group, and the line drawn on the map is of no value except as a rough boundary line between the two local lithological facies of the formation. The same marly beds can be seen at the north-western end of the long railway cutting S.W. of North Moreton, and again in the roadway up the hill south of Little Wittenham. An interesting section is exposed in the brickyard at Culham, and the section seen at the eastern end of the pit in 1887 was as follows : — Ft. In. [4. Light grey laminated clays, very micaceous in the p ,, \ lower part, Hoplites interrwptus, etc. - - 16 Liault j 3 Hard sandy clay full of small quartz pebbles, with some phosphatic nodules and casts oi fossils 2 6 16 Kim. f 2. Bright brown sandy ferruginous limestone Clay. 1 1. Dark grey clay - Prof. Phillips has recorded the following fossils from this localityi : — Ammonites dentatus [Hoplites inter- Inoceramus concentricus (large) ruptus (Brug.)} Nucula pectinata Ammontes lautus Pecten quinquesulcatus [P. quinque- Belemnites minimus costatus J. Saw.'] Dentalium, probably D. decussatum Plicatula pectinoides Eostellaria Cyclocyathus Fittoni Solarium conoideum Balanus Coniferous wood. Mr. Osborne White described the section^ visible at this place in 1903 "and his account agrees closely with that above given. The face had doubtless been cut further back and his measure- ments were probably taken more to the west than mine, for the exposure described by him includes pockets of the surface gravel, the thickness of the Gault clays being about 20 ft. and the pebbly basement bed having diminished to 13 in. He \ Quart. Journ. Geo]. Soc., vol. xvi, V. 309. ^Proc. Geo!. Assoc, vol. xviil, p. 303. 14 UPPER CRETACEOUS. remarked that the Gault here worked " formed part of a north- westerly proiecting tongue of the main mass underlying the low ground on tlie south side of the Thames, and had evidently been deposited in a trough-like hollow of which the sides consisted of Lower Greensand and the bottom in part of Kimeridge Qlay." The following fossils have recently been obtained from the Culham pit by Mr. Osborne White : — Bed S.— Pentacrinus sp. Serpula sp. Inoceramus concentricus Parle. Lima (Plagiostoma) globosa (J. de C. Sow.) Lucina sp. Pecten (Syncyclonema) orbicularis J. Sow. „ (Neitnea) quinquecostatus ? J. Sow. „ (Chlamys) robinaldinus d'Orh. Pteria sp. Fragments of two ammonites, ill-preserved; Tbese are probably Cleoniceras heudanti (Brongn.) or an allied form, and Dou- villeiceras mammillatum (Schloth.). Bed k.— Hoplites interruptus {Brug.) Belemnites minimus Lister Inoceramus concentricus ParTc. The above were named in the Palseontological Department. The only other noteworthy exposure of Gault is at the Clare Brickyard, marked " Brick Works " on the old 1 in. map, about a mile N.W. of Clare. This was visited by Mr. Blake in 1898, who contributes the following note ; the clay is of a light bluish-grey colour with a little "race," a few ferruginous concretions and small phosphatic nodules ; the face exposed was only 3 ft. deep, but other portions in previous years had been worked to a depth of 21 ft., and according to the foreman many fossils had been found. From this brickyard Mr. Blake obtained a specimen of Schloenbachia rostrata (J. Sow.). Mr. J. H. Blake noted in 1900 that " The hill to the north- west of Chislehampton has been proved by a boring 60 ft. in depth, made this year near the top of the sloping ground opposite Church Farm, to consist of bluish-grey clay, blackish in places. It is apparently Gault overlying Kimeridge Clay." ^ A small area of Gault was mapped by J. H. Blake on Pebble Hill, Toot Baldon — a hill named from a house called " The Pebbles " (now the Koebuck Inn), in the wall of which nine pebbles are inserted in the form of a diamond. . There are tracts of clayey ground on March Baldon Green, and around Windmill HUl in Nuneham Park. These may be Gault. Upper Greensand. It will be convenient to indicate first the principal exposures in the malmstone, which forms the main mass of the Upper Greensand, and then to trace the course of the narrow band of glauconitic marl and sand which lies between the malmstone and the Lower Chalk. Where the beds of malmstone begin to come in there is always a marked rise in the ground, in other words the outcfop of tftfe ^ 'Summai-y of Progress' for 1900 {Hfem. Geol. Sxri:), p. 120. UPPER OREENSAND. 15 malmstone forms a ridge with a fairly steep slope or escarpment to the north and north-west, and a gentle slope in the direction of the dip. The malmstone tract enters the area of this map between Didcot Newtown and East Hagboume. It has been dug by the roadside south of Didcot Church and there are good sections of it in the cuttings on the line to Newbury south-east of Didcot. The beds seen in the first of these have been mentioned on p. 13 ; in the next cutting at the north-west end there is at he base a dark sandy clay (Upper Gault), like that at Didcot, succeeded by grey sandy marl which passes up into soft hght grey malm with bands of hard calcareous malmstone ; these beds occupy a syncline at the base of which a nearly black sandy marl is seen, apparently replacing the upper part of the grey marl. The beds then rise to the south-east and the first bridge passes over the centre of a low anticlinal curve, this being well marked by a bed of hard siliceous stone which has a yellowish staining. South-east of this bridge there is a second syncline, and then a roUing dip which brings in higher beds of light grey siliceous stone near the second bridge. At Haddon Hill, on the road to Wallingford, there is a small pit in rnalmstone showing a hard yellowish bed like that of the cutting dipping at 3° westward. There is another pit about 6 furlongs further west by the road. Sinodun and Brightwell Hills consist mainly of malmstone, exposures of which can be seen by the roadside south-west of Little Wittenham and in a shallow cutting south of Castle Hill. Behind the farm buildings south of Brightwell Hill a bank shows 6 ft. of soft grey sandy marl with lumps of hard calcareous stone, and a small pit below is dug in massive grey siliceous and micaceous stone of a brownish- grey colour when wet, but drying to. a light chalky-looking rock. At Satwell spring-head there is a soft greenish-grey stone overlain by soft grey sandy marl, and in the lane south of the Bell Inn soft micaceous malmstone can be seen in the bank. The best exposure in this district, however, is in the road- cutting near ShUlingford Bridge, a considerable thickness of light grey malmstone is here seen, drying so white that it looks like chalk until closely examined ; below it is grey sandy marl ; it was doubtless from this exposure that the specimens examined by Dr. Hinde were taken (see p. 12) ; the stone has also been quarried in the cliffs behind the Swan Hotel. On the eastern side of the Thames valley the malmstone beds emerge from beneath the gravels near the village of Roke, and rise into a well-marked ridge which runs thence to the north- east.' The malmstone is exposed in a small pit about half a mile N.E. of Roke, and again in a larger pit where the road crosses Hollantide Bottom. From these two quarries were obtained — Hoplites auritus {J. Soiu.) Ostrea sp. Pecten (Syncyclonema) orbi- Grammatodon carinatus (J. Sow.) cularis, J. Sow. Efchinospatagus sp. Aporrhais parkinsoni (J. de G. Sow.) 16 UPPER CRETACEOUS. The base of the permeable beds is marked by the spring-head N.E. of Berrick, where a layer of hard micaceous stone rests upon soft olunchy marl. Malmstone has been dug near Whitehouse Farm, and again at tlie corner of the lane east of Cad well Farm, where the stone is grey and apparently more calcareous. At Cad well Spring there is similar stone overlying marly clay, the former containing large Aucellina gryphceoides (J. de C. Sow.). Thence the beds pass through Brightwell Park, and are exposed by the side of the road near Brightwell Rectory ; a strong spring rises in the Rectory grounds, and the water is led befleath the road and the watercourse has been widened into a watercress-bed. At Cuxham soft rotten malmstone can be seen in the watercourse below the corn-mill, and good hard whitish stone is exposed at the entrance of the field road to Pyrton Heath Farm. Between Cuxham and Easington the malmstone ridge is divided into two parts by a longitudinal valley, and the best sections occur on the outer ridge. Light grey malm of light specific gravity is exposed in a pit two furlongs S.E. of Easington and in the road cutting just above. The road cutting down Clare Hill gives a nearly complete section of this division. At the top near the guide-post there is a tough calcareous marl with a few scattered green grains, the next thing seen is hard grey malm- stone, and there is at least 40 ft. of this ; opposite the bench mark of 330 ft. a layer of malmstone is seen overlying a foot or two of softer micaceoiis marl ; no stone was seen below this, the lowest water-hole showing 3 or 4 ft. of tough grey micaceous and calcareous marl with HopUtes aiiritus, which might be classed as Malmstone marl or Upper Gault marl. Near Clare South Farm there is a pit in siliceous malmstone, which does not seem to contain any fossils except Aucellina gryphaeoides and Pecten- orbicularis. Another pit by the roadside, just south of Stoke Talmage, shows about 8 ft. of similar malmstone in regular beds, which break up into small angular blocks and pass up into a marly soU. The next exposure is at Wheatfield, on tlie south side of the angle in the road east of the church. Here a small quarry shows the following beds : — Ft. In. Soil and weathered grey marl - 2 Massive malmstone rock - - 3 Tough grey micaceous marl, becoming rather softer below, seen for - 8 At Adwell there are two fine spring-heads, the water issuing from the malmstone, but no open sections were seen. Beyond Adwell the stone forms a promontory, along which runs the main London and Oxford road and the stone is exposed in the road-cutting less than a mile S.E. of Tetsworth. Thence the feature can be followed to the springs by Copcourt Farm and Postoombe. At Chinnor by the road to Thame, about half a mile north- Avest of the church a well was sunk in 1885, and the beds passed through were said by the workmen to be as follows : — Ft. In. Soft grey marl - ... 10 Eagstone in rocky beds separated by layers of grey marl, the lowest being a bed of rock with water at its base - - - 27 Much of the material brought up lay on the ground, and the stone was seen to be an impure calcareous malmstone, some of the lower beds containing fossils in plenty, HopUtes auritus UPPER GREENSAND. l7 (J . Sow.), Desmoceras planulatum (J. de C. Sow.), and Aucellina Ijryphceoides (J. de C. Sow.), being obtained. From this section it is evident that the malmstone is splitting up and thinning out, soft micaceous marls coming in, and these are found to thicken still more at the expense of the stone beds as the for- mation is traced through the next Sheet.i Glauconitic Beds. The outcrop of these forms a narrow band in which exposures are not frequent. At West Hagbourne (Sheet 253) green sand can be found here and there along the watercourse by the orchard of Manor Farm, but near Upton it passes beneath alluvial deposits, from which it emerges between Blewbury Mill and Sheeneroft Farm, the house and buildings of this farmstead standing upon it. A little further eastward, however, it passes below the spread of gravel and alluvium near Aston Tirrold. It is next seen for a short space along the shallow cutting of the Great Western Kailway between Cholsey and South Moreton, but the whole of Cholsey Hill consists of Chalk Marl, and there is no sign of the glauconitic beds on its northern flank, while around Wallingford its outcrop is entirely concealed by the Thames vallev gravels. On the otKier side of the Thames valley the upper beds of malmstone, and presumably the green sand also, emerge from under the gravels to the east of the hamlet of Roake, but I saw no exposure of the glauconitic beds. Under favourable circum- stances green sand might be found in the ditch or watercourse which runs north-eastward to Rumbolds Lane, but this lane is on the Chalk Marl, and to the northward there is malmstone, brought up apparently by a fault, so that the green sand is cut out. The lowest portion of the glauconitic beds appears to cap the malmstone on the west side of BrightweU Baldwin, for in 1886 I found a soft marl full of green grains in the field-road leading out of the lane 160 yds. south-west of the church; and was also informed by the sexton that such marl " with green specks in it " underlay the greater part of the churchyard. This is on the north side of the supposed line of fault, and no other evidence was obtainable, the ground south of the village being obscured by a great depth of soil and gravelly wash. At Cuxham no trace of green sand could be found, and from the close proximity of exposures showing malmstone and Chalk Marl respectively, it was inferred that the intervening beds were faulted out. South-east of Cuxham there appears to be a cross fault, and it was surmised that the malmstone and green sand might be brought up on the further side of this fault at the north-east of the " Middle Mill," but no trace of the green sand could be found. The pools and rushy ground north-east of Watlington Mill may possibly indicate the base of the Chalk Marl. 1 See Whitaker, Memoir on Geology of Lomloii, vol. i. 1889, p. 52. 10322. C 18 UPPER CBETACEOUS. The green sand is first seen again at the Model Farm north of Shirburn Castle. Here I was informed by Lord Macclesfield's steward that dark green sand had been found in the orchard, and in the field to the south of it ; also that it underlay the gravel on which his house stands, and was passed through in digging the well. Thence the outcrop passes to South Weston, and can be found in the bank of the roadside south of the pillage ; curving round by Nethercroft fishpond it passes below South Weston Church, and runs thence northward through the fields above Adwell Springs ; there I proved its outcrop in the dry ditch which runs up from the Springs to the plantation on Adwell Cop. ** From Adwell the outcrop was traceable by feature to Aston Eowant, ■where the dark green sand was found in the bank of the watercourse a quarter of a mile N.N.W. of the church. Thence its course is along low and obscure ground, but it was seen along the watercourse north of Crowell for about 150 yards below the point where the streams from the various springs unite ; all these springs rising from the rocky beds in the Chalk Marl, and not from its base, as was erroneously concluded when the old geological map (Sheet 13) and accompanying Memoir were published. The outcrop of the'green sand passes through the northern part of the village of Chinnor. Oqtmeks. Here and there the malmstone plateau supports outliers ot the green sand, which are generally capped by patches of Chalk Marl. Sinodun and Brightwell Hills, north-west of Wallingford, are outUers of this kind., but the outcrop of the glauconitic beds is narrow and its presence can seldom oe detected. On the hill above Sotwell glauconitic marl was seen in the lane leading to the Hill Barn. The hill east of Easington is capped by a patch of the flauconitic beds from which the Chalk Marl has been removed, ut which are covered in part by flint gravel. In the road about two frirlongs east of Easington there is yellowish glauco- nitic sand passing up into hard glauconitic marl tvith brown patches like soft phosphatic nodules, this appears to be succeeded by soft dark green sand, but it is more Hkely that the beds have slipped over one another down the slope. At the cross-roads on Clare Hill soft grey marl full of glauconitic grains is exposed in the bank, and this evidently underlies the green sand and passes down into malmstone. Gilton Hill, near Wheatfield, is an outlier of the glauconitic beds capped with Chalk Marl, but no exposures were seen. The manner in which such outliers have been formed by the gradual isolation of a promontory through the recession of spring-heads and the wash of rain is admirably illustrated in the position of Adwell Hill, which may be regarded as a case of the arrested development of an outHer, 19 CHAPTER V. UPPER CRETACEOUS (continued). Lower Chalk. By a. J. Jukes-Browne. The Lower Chalk, as now defined, includes the beds formerly- called the Chalk Marl and the Grey Chalk, together with a certain thickness of the whitish chalk, which overlies the latter. The Lower Chalk is limited by the green sand of the Selbornian group below and the hard nodular chalk of the Melbourn Rock above, and in Berkshire and Oxfordshire its total thick- ness varies from 180 to 220 ft. It is divisible into two broad zones — (1) the zone of Schloen- hachia varians, which corresponds with the Chalk Marl or Totternhoe Marl, as defined by Mr. Whitaker in 1865 ^ ; and (2) the zone of Holaster subglobosus, which has the Totternhoe Stone at its base, and the " Belemnite Marls " or subzone of Actinocamax plenus at the summit. The zone of Schloenbachia varians does not consist entirely of soft marly chalk, for it includes many beds of hard grey chalk, which alternate with the bands of softer chalk. One of these hard beds is persistent throughout the counties of Oxford and Bucks, and being underlain by a stiff argillaceous marl, throws out water in a series of strong springs. This bed has been indurated by the infiltration of calcite, and is in some places 4 or 5 ft. thick ; its outcrop frequently forms a marked rise in the ground, and is consequently traceable as a feature. As there are good sections of it near Risborough, in Bucks, it may be called the Risborough rock-bed. Fossils are generally abundant in it. The total thickness of this zone is from 100 to 120 ft. The Totternhoe Stone has been described in several Survey Memoirs, and is a firm grey chalk which generally contains small scattered fragments of brown phosphate of lime, and frequently larger phosphatic nodules which are often greenish outside. In the area now under description it is only a thin band varying from 2 to 4 ft. thick, and it appears to die out westward in Berkshire, for it has not been traced beyond Chilton, which is a village just outside the western border of Sheet 254. The Totternhoe Stone has a gritty feel to the touch but- is not a sandy chalk, neither is it calcified like the Risborough Rock, but its character is due to the quantity of even-sized fragments of shell which enter into its composition. Rhynchonella mantelliana (J. de C. Sow.) and Kingena lima (Defr.) are generally abundant in it. X Quart. Jourii, Geol. Soc, vol. xxi, p. 398. 10322. C 2 20 UPPER CRETACEOUS. Above the Totternhoe Stone there is always a certain thick- ness of grey or greyish chalk, blocky and indistinctly bedded ; this often passes up into whiter chalk, but the change is gener ally rapid, and sometimes the grey is divided from the whitei chalk Dy a bed of hard grey chalk containing phosphatic nodules and much disseminated phosphatic matter in minute grains. Of the whitish chalk there is generally about 50 or 60 ft., and the total thickness of the blocky chalk is from 80 to 100 ft. Fossils are not abundant in any part of it, but Holaster subglobosus (Leske), Hoi. trecensis Leym., and Meticcanthoplites rotomagenee (Brongn.) may usually be found when there is a good exposure of the zone. At the top of this zone is the band which has been called the "zone o{ Beleinnitella plena," hut it is of small thickness and its small fauna is not so different from that of the beds below as to be really of zonal importance, though it may be regarded as a sub-zone of the comprehensive zone of Holaster subglobosus. In the counties of Berkshire, Oxfordshire, and Buckinghamshire this sub-zone consists of two layers of grey shaly marl, separated by a bed of firm compact white chalk ; each member varies in thickness from a few inches to 2 ft., but the whole band is seldom more than 3 ft. thick. The lower marl band is the most variable of the three, being sometimes merely a seam or marly parting, but occasionally swelling to a foot or 18 in. The hard white course appears to be of constant occurrence in this district, and the upper marl is generally about a foot thick. This upper marl has yielded the characteristic Belemnite (Actinocamax plenus Blainv. sp.) more frequently than the other beds ; but it will be convenient to speak of the whole band as "the Belemnite Marls." Rhynchonella cuvieri d'Orb. and a variety of Mh. {Mcatilis (J. Sow.) are not uncommon, and occur in all three ayers, as also does a small globose variety of Ostrea vesicularis Lam. Stratigrapliical Details. CHALK MARL. Zone ot Schloenbachia varians. Hard chalk marl can be seen at several points round the villages of Blewbury and Aston Upthorpe, but the only pit-section is near Sheencroft Farm, north-east of Blewbury. South of the farmstead there was in 1886 a small pit exposing about 7 ft. of soft grey marl, with included lumps of hard whitish glauconitio stone; this stone resembles some varieties of malmstone, is apparently very siliceous, the silica being probably organic, and the grains of ^lauconite are only just large enough to be seen without a lens. The marl in which the stony lumps occur passes down into a tough grey marl, and the tenant of the farm stated that it was much the same for another 8 it. This exposure is not far from the outcrop of the Greensand (see p. 17). North of Aston Tirrold the lower part of the Chalk Marl is concealed by valley gravel, and east of that village it is covered by alluvium, but the higher beds form the slopes of LoUington Hill south of the farm of the same name (spelt Loringdon on the old Ordnance Map) ; on the north- west side of this hill there is a small pit in tough blocky- grey chalk, but LOWER CHALK. 21 this probably belongs to the zone of Holaster suljglobosus, though the absence of fossils makes it uncertain. Half-a-mile east of this hill and by the side of the road to Cholsey, is a larger pit which is certainly in the zone of Schloenbachia varians. It is about 12 ft. deep, in hard marly chalk with a course of softer marl about 4 ft. from the surface. Fossils are not abundant but Schloenbachia varians (J. Sow.), Rhynchonella mantelliana (J. de C. Sow.), and fragments of Inoceramus were found. A very good exposure of the central part of the same zone is to be found in the railway cutting near Moulsford Station. This is about 20 ft. deep near the middle, the upper 10 or 11 ft. consisting of courses of marly chalk separated by layers of soft shaly marl ; below are about 8 ft. of soft grey marl with occasional lumps of harder material, resting on 2 or 3 ft. of very hard rocky chalk, weathering into lenticular lumps. Fossils are abundant throughout, especially Schloenbachia varians (J. Sow.), Mantelliceras mantdli (J. Sow.), and Inoceramus latus Goldf. and a Bhynchonella like Bh. grasiana d Orb. A large part of Cholsey stands on Chalk Marl, but eastward this passes beneath the gravel of the Thames valley. At the County Lunatic Asylum a boring reached the base of the Chalk Marl at 46 ft. from the surface. ^ On the eastern side of the Thames the Chalk Marl emerges from beneath the gravel at Mongewell, and hard marly rock (Risborough rock) is visible at the spring heads at the upper end of the fine millpond. Thence the outcrop runs N.N.E. through Newnham Park and Crowmarsh, and the highest beds were exposed in the quarries on Crowmarsh Hill (see p. 25). In Marsh' Wood, N.E. of Crowmarsh, there are springs, but no good section, though the water probably issues from the rock. From the water- course a deep ditch has been dug northward, and at the north end of this, just one mile N.E. of Crowmarsh, I found a dry greyish marl full of green grains, so very glauconitic as to resemble the basement green marl ; but whether it is the basal marl brought up by a fault or a glauconitic layer higher up in the marl could not be determined. In a field on the west side of Clay Lane, and about 6 furlongs S.W. of Evvelme Mill (Fyfield on the 1-in. map) a well was being dug in 1886 through soft clay marl into tough brownish sandy chalk or " clunch," with many fossils (see p. 27), the lowest beds then exposed, about 1.5 to 16 ft. from the surface, were hard and probably belonged to the top of the Risborough rook. This rock is exposed in a cutting by the roadside south of the mill house, and is here very compact, calcareous and hard. Below the millpond there is soft Chalk Marl in the watercourse. At Ewelme we find the upper and firmer beds of the chalk which underlies tlie Totternhoe Stone exposed at the fine spring heads in the garden of the house above King's Pond. It is a greyish blocky chalk drying nearly white, and the same unfossiliferous chalk is seen in a small pit by the roadside north of Ewelme. Jn Eyres Lane, north-west of Ewelme, soft marl is seen in the cutting overlain by a rubble of hard grey rock ; if this indicates the outcrop of the Risborough rock it is at a level of 300 ft., whereas at Ewelme Mill its level is 245 ft., and we may assume the existence of a fault running along the hollow north of Ewelme with an upthrow of 50 ft. on the north-east side. The existence of such a fault is confirmed by following this contour northward. The next road cutting is overgrown, but the rock was found by picking into the bank. It supports the plateau of Scald Hill, its outcrop running to an old pit by the side of Rumbolds Lane, which is now overgrown but 1 ' Water Supply of Berkshire ' (Mem. Gcol. Sim:), 1902, p. 57. 22 UPPER CRETACEOUS. formerly exposed 5 or 6 ft. of very hard calcareous stone with Schloenbachia varians and other fossils (see p. 27). Beyond and north of this old (juarry the Chalk Marl is cut off by a fault which appears to run from Berwick Prior eastwards to Brightwell and Cuxham (see Fig. 2). In 1899 Mr. Ehodes, visiting the area to collect fossils, found a new quarry open by the roadside near Kumbold's Copse, exposing about 10 ft. of gi^j chalk which probably belongs to the upper part of the Chalk Marl, and is not far below the Totternhoe Stone. He obtained a fair number of fossils from it, including Schloenbachia, varians (J. Sow.), Galycoceras navi- ciilare (lllant.), Pecten {^quipecten) beaveri J. Sow., Inoceramus latus Goldf., Rhynchonella grasiana d'Orb., and a specimen of Palcega carteri H. Woodw. At Brightwell Uppertown, above the spring-head, there is hard grey marly stone like weathered Risborough rock, with fragments of Schloen- bachia varians, and in the bank by the cottages to the eastward there is a small exposure of shaly marl with hard concretionary lumps as large as a man's head, in which I foimd Brachiolites sp. (decomposed), Inoceramus latus, Lima sji. {1 echinata), Natica sp. (? gatdtina) and Schloenbachia varians (J. Sow.). Some other fossils were subsequently found here by Mr. Ehodes. Quarry, Quarry. Eig. 2. — Fault between Berrich Salome and Cuxham. a Malmstone. i Chalk Marl, c Risborough Rock, d Gravel. Jf Fault. It would appear, therefore, that the Risborough rock continues to crop out along the 300 ft. contour which passes just above the spring-head. At Cuxham, south of Manor Farm, there are stronger springs, and here also I found fragments of the hard calcareous rock. A little beyond this, near what is known as the middle mill, the outcrop appears to be cut by a fault, with a throw of some 40 ft., for the Watling- ton springs, which probably issue from the rock-bed, are above the SSO^ft. contour. Ihere is no good exposure at Watlington, but fragments of the rock are scattered over the iield north-east of the church, and the upper beds of the rock are exposed at the bottom of the bank a quarter of a mile S.E. of Pyrton Church. The wells in Pyrton are dug through soft greyish white marl, and find water at about 25 ft. down, but the basal glauconitic marl is nowhere exposed. In Shirburn Park the outcrop of the Risborough rock is at the 360 ft. contour, and there are five springs at this level N.E. of the castle. The strike fault dies out with the north-easterly rise in the beds, and the base of the chalk marl is brought to the surface near the Model farm north of the castle. Soft grey marls are found round Moor Court, and by the roadside east of Nethercote, while the hard rock-bed can be seen above the fine springs which issue from beneath the main road at Lewknor. The feature w ade o ?5 B SQ bo LOWER CHALK. 23 m 6 bo .g o o :f I, o =? .a H ttMsii t- 24 UPPER CRETACEOUS. by the outcrop of this rock can be followed through the fields to the head of the fish-pond near Aston Rowant House. The lowest beds of the Chalk Marl can be seen in the ditch by the road- side north of Aston Church, they consist of grey sandy marls passing down into hard, grey, gritty marl, with softer marl again just before the outcrop of the green sand is reached. Returning to the outcrop of the Risborough rock, its course can be traced to the spring-head at Kingston Blount, and just above this, in the ionnda.- tions for some outhouses, 5 or 6 ft. of hard marly stone were exposed in 1885 ; the same beds were also seen in a sawpit on the north side of Crowell Church. North of Crowell there are several strong springs, but the banks were not clear enough to expose the sub-soil, and the actual outcrop of the rock probably runs between them and the road. At the point where the rivulets from these springs unite into one water- course there is soft Chalk Marl, but just below this there is dark green sand, and thence the base of the marl was traced with some diflBcuIty to the north end of Chinnor. The only exposure found at Chinnor was in the railway cutting at the station, where a few feet of rather hard white chalk were seen, and it was ascertained that the well was 45 ft. deep, being probably carried quite through the rock before finding water. The chalk seen here is not far balow the Totternhoe Stone. Zone of Holaster subglobosus. In the lanes south of Blewbury grey chalk with Holaster siihglohosus (Leske) was found, but no trace of the Totternhoe Stone could be seen, neither was any good exposure of the Belemnite Marls seen when the district was mapped. The central part of the zone, consisting of blocky grey chalk, is exposed in a pit near the main road, south of Aston Apthorpe. Similar chalk is seen in a pit on Lollington Hill to the eastward. The outcrop of the Totternhoe Stone was found by the road to Cholsey, half a mile S.E. of Lollingdon Farm ; it has the usual characters, contains many brown phosphatic nodules, and seems to be 3 or 4 ft. thick. Search was made for its outcrop in Halfpenny Lane, south-west of Moulsford Station, but without success, and the line drawn through Moulsford is entirely hypothetical. South of Moulsford there appears to be a line of fault, for the hard yellow chalk of the Rht/nchondla cuvieri zone occurs at a very much lower level on the south side of Moulsford Bottom than it does on the north side. On the east side of the Thames the outcrop of the Totternhoe Stone is concealed for some distance by river-gravel, out the highest part of the zone can be seen near the " Leathern Bottle " Inn, north of Cleeve. There is a sort of cave here in which a spring rises, and the water is said to have been formerly saline, but the river water was let in either by accident or on purpose, and no saline taste can now be discerned ; the chalk is in massive blocks and gi-eyish white. This part of the Lower Chalk occupies a considerable space to the east of South Stoke, round the slopes of White Hill and Watch Folly ; there is a small pit more than half a mile east of Stoke and another on the north slope of White Hill, but no fossils were found in either pit, nor in the road-cutting south-west of Ipsden. The summit of the zone is exposed in a small excavation by the roadside one and a-half miles east of South Stoke, the beds seen being : — Ft. In. Melbourn Eock, hard and nodular - 2 Grey marl ... . 10 Hard white rocky chalk - touched No outcrop could be found near Ipsden, but on White Hill, between LOWEK CHALK. 25 Ipsden and North Stoke, there is the following section in a pit by the roadside: — Soil and chalk rubble • - from 1 ft. to Melbourn ( Hard nodular rocky chalk in regular beds, yellowish, Koek ( but weathering nearly white ^Bufif-coloured laminated marl with Actinocamax Zone of i P^^'"-'^^ (Blainv.) - 6 in. to ^(.(.jj^g^^g j Hard compact white chalk - 1 ft. to ■ ' Greenish shaly marl, with Ostrea vesicularis Lam. and Rhynchonella - - about Ft. 2 in. 5 1 1 3 Zone of Hoi. sub- fflobosus. ( Firm blocky white chalk, with patches and mottlings i of grey material near the top, giving it a brecci- ( ated appearance 10 The strong spring at North Stoke cannot be far above the horizon of the Totternhoe btone. At the south end of the wood by the side of the main roa,d north of this spring-head is a pit exposing some 20 ft. of the firm white chalk belonging to the upper part of the zone, and beyond Mongewell Farm there is another pit in the same kind of chalk. At the bottom of the road-outting north of this place there is rough-feeling grey chalk which cannot be far above the horizon of the Totternlioe Stone. By the road along the south side of Newnham Park there is a small pit in greyish-white marly chalk containing Metacanthoplites rotomagensis (Brongn.) and Iiuxerwmus latus Goldf. which can hardly be more than 30 ft. above the Totternhoe Stone, and the road cutting to the east of this gives a nearly continuous though shallow exposure of the greater part of the zone. The large quarries by the side of the main road on Crowmarsh Hill are now abandoned, but in 1885 they exposed a nearly complete section of this zone, including the Totternhoe Stone and 18 ft. of the Chalk Marl below. The highest face still shows about 30 ft. of nearly white blocky chalk, between the foot of this and the level on which the kiln stands there must be from 30 to 40 ft. of similar chalk, whitish above but passing down into grey, and containing Metacanthoplites rotomagensis. The bedding is obscure and irregular, but the general inclination is eastward. In the two lower levels below the kiln the following section was seen in 1886 :— Middle Level. Ft. Base of zone of Holaster subglobosus. Chalk marl. Zone of Schloen- bachia varlans. Bubble - .- -. Blocky grey chalk with oblique jointing Discoidea cijlindrica (Lam.), Terebratida bijjU- cata J. Sow., Teredo. Passing down into hard brownish-grey gritty chalk with many phosphatic nodules near the base (Totternhoe Stone) Hard bluish-grey marl, breaking into blocks with a curved or semi-conchoidal fracture Loivest Level. Dull grey sandy stone, rather hard, but splitting into shaly layers and without phosphates Soft grey marl without definite bedding 6 The dip appeared to be S.E. at about 2 de^. I was informed that the Totternhoe Stone was sometimes used for building barns and outhouses and for lining cisterns, etc. North-east of the Crowmarsh Quarry and oast of Coldharbour Farm the 26 UPPER eRETA^EOtrS. cutting for a cart road exposes the junction of the Lower and Middle Chalk, the succession being : — Ft. In. Brown gravelly soil - 10 Bubble with pockets of gravel - - 2 Melbowrn Bock, hard nodular rocky chalk 3 T, 7 -J r Soft grey laminated marl 1 ^«^,f*™;^« J Hard compact white chalk- 1 Marls. (_ rpj^-jj gga^^ j,f gjgy jjiarl 1 Hard white chalk, seen for - - - - 5 Lower beds consisting of hard whitish blocky chalk are exposed in the limekiln quarry on Beggarsbush Hill, the depth of which is between 30 and 40 ft. This chalk contains veiy few fossils, Mr. Ehodes' search yielding only Ostrea vesicularis Lam., Terebratula semiglobosa J. Sow., a Plocoscyphia, and a fish bone. The next exposure of this zone is in the cutting for Day's Lane, south of Ewelme, this is through the lowest beds and the Totternhoe Stone, but is much overgrown. North-east of Ewelme part of the chalk surface is obscured by a deep covering of flint-gravel, and even where this is absent there are few exposures. The springs near Britwell Priory appear to rise from the grey chalk which overlies the Totternhoe Stone. At the spring-head south-east of Watlington, grey gritty stone was found which was taken to be Totternhoe Stone, though the exposure was too small for certainty. It is, however, on the line to which its outcrop would be shifted by the fault which is believed to run south-eastward from Cuxham. There is no traceable feature beyond this, but the line is drawn on by contour to the next exposure. The white chalk, which forms the highest part of the zone of Holaster subglobosus, may be seen in the railway cutting south-west of Lewknor, and in a pit by the road south of that vUlage. The same chalk is exposed in the cuttings near Aston Rowant Station. By the side of the road less than half a mile south of Crowell there is an exposure of tough grey chalk, 3 or 4 ft. thick, resting on crumbling marl ; this may be Totternhoe Stone or the bed seen in Crowmarsh Quarry 8 ft. below it. South-east of the point where this road crosses the Icknield way, the Belemnite Marls were seen dipping sharply into the hill side. From the higher of two pits on the north-east side of the lane leading from Crowell to Crowell Hill, Messrs. C. P. Chatwin and T. H. Withers have lately obtained small subangular pieces of light brown, and of dark glauconitic, sandstone ; also the following fossils : — Exogyra haliotoidea {J. Sow.) Discoidea cylindrica [Lam.) Ostrea vesicularis Lam. Holaster trecensis Leym. Lima globosa {J. de C. Sow.) „ subglobosus (Leske) Terebratulina striata Bav. Fossils from the Lower Ghalk. The following is a list of the fossils which have been found at different localities in the area described. All have been obtained either by myself or the fossil collector, Mr. Rhodes, except those from Pyrton, which were found by Mr. Montague Smith, who presented them to the Woodwardian Museum, Cambridge, and those from Crowell above mentioned. The localities in the zone of Schloenbachia varians are indicated by letters thus : m^- = Moulsford cutting, c = Crowmarsh, . e = Clay Lane near Bensington, r = Eumbold Lane and Bright- well, p = Pyrton. 1 A few (ill) were found by Mr. LI. Treacher and by Messrs. Chatwin and Withers, LOWfiR caALK. m Beryx sp. FiSCES. Grustaoei. g a' o >3 Cytherella? Palaega carteri H. Woodiv. Pollicipes glaber F. A. Roemer Gepsalopoba. Anisoceras armatum % {J. Sow.) - Calycoceras naviculare (Mant.) Hoplites falcatus (Mant.) - Mantelliceras mantelli (/. Soto.) Metacanthoplites rotomagensis (Brongn.) Schloenbacnia varians {J. Soiv.) „ coupei Brongu. Turrilites costatiis Lam. - „ mantelli Sharps „ tuberculatus Bosc. Actinocamax plenus (Blainv.) Nautilus elegans /. Sow. Gasteropoda. Aporrhais cf. carinata {J. de C. Sow.) Avellana cassis d'Orb. Natica vulgaris Betiss Pleurotomaria perspectiva ? (Mant.) „ [flat.] . Turbo sp. - - - - LAMELtlBR INCHIATA. Aucellina gryphaeoides (J. de G. Sow.) Cardita cf. tenuicosta (J. de C. Sow.) Exogyra naliotoidea (/. Sow.) - Grammatodon carinatus (/. Sow.) [Cucullsea Auctt.]- Hinnites sp. Inoceramus latus Gold/, (non Mant.) „ striatus J. de G. Soiv. ,, sp. I/ima aspera (Mant.) % ^' „ \ „ (Mantellum) elongata (J. de C. Soiv.) . „ var. echinata Eth. ,',' (Plagiostoma) globosa (/. de G. Sow.) Ostrea vesicularis Lam. .... Pecten (^quipecten) beaveri J. Sow. - P m r P m e p (m) m e r p (m)e p e r r P (m) (m) rp P m c e r p m + + + + + + + + 28 UPPER CRETACEOUS. of _ \ ichia IS. S CO 1 Zone Schloenbc varioA 1. 1 g Pecten (Syncyclonema) orbicularis J. Smo. „ (Neithea) quinquecostatus J. Soiv. - Pholadomya decussata Phill. Plicatula inflata J. de C. Sow. m e r c P c r + Bbacbiopoda. Rhynchonella grasiana d'Orb. - „ mantelliana ( Exposures Along the Escarpment. By A> J. JukeS'BrownE: The outcrop of the Chalk Eock, and consequently that of the zone of Holaster planus, enters the area of Sheet 254 about three-quarters of a mile south of Blewbury, and it runs out along the promontories of Cholsey Downs, Moulsford Down, and Thurle Down. In this district surface exposures are occasionally visible, but no quarry or clear road-section was seen during the progress of the Survey in 1885. After passing southward by Streatley and Basildon,^ it re-enters our area on the eastern side of the Thames Valley to the south-ea,st ot Cleeve, and in the road-cutting about a quarter of a mile east of Fairfield House, close to the 300 ft. contour line, the following section was seen in 1885 r — Ft. 7. Soft white chalk with a thin layer of flint at base 5 / 6. Hard yellowish limestone in loose lumps 1 5. Micraster Beds, consisting of hard lumps of white chalk embedded in soft powdery chalk, with a few scattered flints - - - 12 %^\ 4. Chalk Kock. Hard white limestone without green fS[o ' grains passing down into very hard compact "-^ yellowish rock with much glauconite, and contain- \ ing several layers of green-coated nodules 5 3. Hard rocky chalk passing down in rough nodular chalk -. - - 2 2. Layer of soft shaly marl Oj 1. Firm bedded greyish- white chalk, nodular in places 4 About - 30 The Micraster Beds are here less productive than usual, but I ffiund Echinocorys scutdtus Leske, Spondylus sninosus (J. Sow.), and Terehratula carnea J. Sow. Messrs. Chatwin and Withers have obtained some fossils from the Chalk Eock here.a The outcrop of the rock can be traced round the hill into the combe by Elvendon Farm, where I found fragments of it in the bank by the roadside. It is exposed in Eed Lane three-quarters of a mile N.W. of Woodcote at a level of about 380 ft., showing in the bank as hard, cream-coloured rock, much of it with green grains from 3 to 4 ft. thick. In Garson's Lane, one mile E.S.E. of Ipsden, the base of the rock is seen in the pits by the roadside at a level of 426 ft., a hard, yellow limestone 'with green nodules, and 50 yds. further east there is white, powdery chalk, with hard lumps (the Micraster Beds). No sign- of the rock could be found in the road-cutting above Well Place, though fragments of the rock had been used for making the road, and there is a small grass-grown pit at the level where its outcrop should be. Neither could it be found east of Hailey, but on Batchelor's HUl, east of Wicks Wood, its outcrop was found at a level of about 460 ft. In 1886 it was not exposed along any of the roads between Warren Hill and Ewelme Downs, and hardly a fragment of it could be found ; thus shovnng how completely the outcrop of the rock may be hidden beneath soil and wash. Mr. Osborne White, however, states that a little of this rock, with its green-coated nodules, can be seen between the top of the talus and the turf at the upper end of the pit in TerehraUdina-chalk to 1 See ' Geology of the Country Around Reading' {Mm. Geol. Siiri:), p. 9. 2 See JP/oc. Geol. Assoc, vol. xx, j). 393. IrPPEIt CHA.LK. 39 the south-east of Potter's Farm. He also points out that the outcrop of this bed must cross the main road from Henley to Oxford nearly half a mile further to the north-west, and some 80 ft. lower than is shown on the 1-in. map ; for a small roadside excavation, rather more than a furlong north-west of Ambrose Farm, shows yellowish nodular chalk which clearly belongs to the upper half of Holaster planus zone. In view of these facts it is probable that the Upper Chalk boundary line has been mapped at too high a level throughout that part of the escarpment which lies between Warren Hill and Ewelme Downs. From the pit near Ambrose Farm, just mentioned, Mr. White obtained :— Inoceramus cuvieri J. de C. ,Sow. ^. » sp. Dimyodon nilssoni {TIag.) [= Plicatula sigillina S. F. Woodio.] Lima (Plagiostoma) hoperi {Mant.) Spondylus spinosus (J. Sow.) Rhynchonella plicatilis (/. Soiv.) Terebratula carnea J. Sow. J, semiglobosa J. Sow. Cardiaster cotteauanus d'Orb. Cidaris sp. Echinocorys scutatus Leslie (gibbous form)' Holaster placenta Ag. „ planus (Mant.) Mioraster priBcursor Howe Pharetrospongia strahani SoZ/ax. Porosphiera globularis (Fhill.) Ventriculites infundibuliformis S. Woodw. The examples of Micrasfer jmtciu-sor have "slightly inflated" inter- poriferous areas. On White Hill, north-west of Swincombe, the rock crops out in the road at a level of 521 ft. Passing out of the combe it juts out westward in the. fine promontory of Swincombe Down, and fragments may be found near the end of the Danish entrenchment, which runs along the north side of this hill. In Howe Lane (south of Howe Farm) a little of the firm, lumpy, beds at the base of the rock was visible (in 1906) in a ditch near the bottom of the hill, at about 550 ft., and a few feet higher than the pit in TereliratuUna- chalk noticed in the last chapter (p. 33). On Watlington Hill fragments of the rock occur in the deep ditch tor carrying off rain-water just above the 600 ft. contour, and there are old pits by the roadside, whence I was told that ". rag " for road mending and for building walls had been dug. The lower part of the wall in the yard of the Fox and Hounds Inn, Watlington, is built of Chalk Rock, which was also used for road material when the parish tad the care of the main road to Henley. In the roadway on the north side of Shirburn Hill the outcrop is not clear, but what appeared to be the upper bed of the rock, as seen further north, was observed at 700 ft. overlain by chalk with a layer of tabular flint. Near the road to Lewknor, down Bald Hill, and only just above the 600 ft. contour line, there is a pit exposing. Chalk Rock, but though seemingly undisturbed, this can hardly be in situ, and is probably part of a mass that has slipped down the steep slope. On the east side of Beacon Hill, which is the next promontory, fragments of rock were found at a level of about 670 ft., and this is exactly the level of its outcrop at the quarry by the London road on Aston Hill. At this quarry there was (in 1885) an excellent section showing two separate beds of Chalk Rock, with the Micraater Beds between them, as follows :— 4.0 UPPKE CRETACEOUS. Upper Rock. Micraster Beds. Chalk Rock. 4. Soft, thin-bedded chalk, with a layer of flints in the middle -- - - - -- 3. Course of compact, yellowish rock, with green nodules - - - -- 2. Dull, white, lumpy chalk, consisting of soft, mealy chalk, with hard lumps and many fossils, especially near the base, where it contains much glauconite and a layer of peculiar flints - - - - - 1. Loose, rubbly rock, with green grains, green-coated nodules, and many fossils. Passing down into Compact cream-coloured rock, with another layer of nodules about 2 ft. down (base not seen) Ft. 14 - 4 26 The bedding is nearly horizontal, and small slips or faults are numerous. There is a remarkable abundance of glauconite grains, the base of the chalk above the lower rock being in some places more of a greeusand than a chalk, and they extend upwards for at least 2 ft. The flints at this horizon are rough and carious with hollow spaces. After 1885 this quarry remained for many years unworked and obscured by talus, but was re-opened in 1907, and was visited by Messrs. Chat- win and Withers, who carefully collected from each horizon and have kindly placed the results at our disposal. In the chalk above the upper rock they found : — Micraster precursor Eoive (of the Echinocorys seutatus Leske (bits) M. cortestudinarium zone type) Holas.ter placenta Ag. Rhynchonella limbata (Schloth.) Terebratula carnea J. Sow. „ semiglobosa J. Sow. From the upper rock (3) they obtained the foUowmg : — Micraster cortestudinarium((xo^d/.) Inoceramus sp, „ prsecursor iSoitie ^' "^"" " Holaster sp. (bits) Bourgueticrinus sp. Pleurotomaria perspectiva (Mant.) Spondylus spinosus (J. Sow.) Inoceramus sp. Serpula fluctnata J. Sow. Membranipora elliptica Eeuss Ventriculites iropressus T. Smith Dimyodon nilssoni {Hag.) [ ^^ Pli- catula sigillina Woodw.] Terebratula carnea J. Sow. Serpula granulata J. de C. Soiv. Plocoscyphia convoluta {T. Smith) From the Micraster Beds they obtained ; Micraster prsecursor Howe „ leskei {Desmoul.) Holaster planus {Mant.) „ placenta Ag. Echinocorys seutatus Leahs Spondylus spinosus (■/. Sow.). ,, latus {J. Sow.) Terebratula carnea J. Soiv-. „ semiglobosa J. Sotv. Nautilus sp. Oxyrhina sp. Serpula fluctuata /. de C. Sow. „ plana S. Woodiv. Stomatopora gracilis (J/. Edw.) Proboscina augustata [d'Orb?) Berenicea disciformis {Hag.) „ cf. phlyctsenosa Kextss „ cf. contracta Sedey From the Chalk Hock (No. 1) the following were obtained ; Nautilus sp. Crioceras ellipticum {Mant.) Barbatia cf. geinitzi {Reuss) Inoceramus sp. Pachydiscus peramplus {Mant.) „ sp. Avellana cf. humboldti Muller Cerithium cuckhamsliense Woods Dentalium turoniense Woods Solariella gemmata {J. de C. Sow.) Trochus beroscirensis Woods Turbo geinitzi Woods Pleurotomaria sp. Septifer lineatus (J. de C. Sow.) Spondylus spinosus (J. Sow.) Terebratula carnea J. Sow. „ semiglobosa /. Sow Rhynchonella cuvieri c?'0r6. „ plicatilis {J. Sow.) Serpula ampullacea J. de G. Sow. Holaster planus {Mant.) Echinocorys seutatus Leske Parasmilia centralis {Mant.) Clioiia cretacea {Portlock) UPPER CHALK. 41 It may be mentioned that five specimens of th/e Nautilus were obtained from the topmost loose glauconitic bed. About a furlong east of the above, and on the lower road from Warren Farm, there is an old limekiln in a slipped mass of chalk where a similar section must have formerly been visible, out it is now much hidden by talus. The upper beds are seen again in a small pit by the road east of Kingston Grove ; here the section is : — Zone of Mivraster cortestudiiwriam. /3. Zone of Holaster planus. Ft. White chalk with scattered flints, with a line of large flint nodules at the bottom - Thin-bedded white chalk with two thin seams of tabular flint - - - 4^ Hard cream-coloured rock with green nodules and ferruginous concretions ; well defined above, but merging below into the underlying chalk - - - - - 1-2 2. Micraster Beds. — Hard yellowish chalk which becomes nodular below, consisting of hard lumps, embedded in soft greyish mealy chalk - - - - - -14 1. The Chalh Rock is hidden by talus, but is seen on the bank on the other side of the road. The upper rock bed (3) was still well exposed in 1906, but, though closely examined, yielded no fossils of interest. The base of the rock is exposed at the top of an old pit on the cart road down Crowell Hill ; and another good section of the whole group occurs in a pit by the main road on Chinnor Hill, exactly on the contour line of 700 ft. Fig. 4 is a sketch of this pit. Fi(j. 4. — View of a Quarry on Chinnor Hill. ^3 42 UPPER eRfitACtOtJS. 4. White chalk with three layers of flints, the lowest nearly continuous - - - - - - - - - --10 ' 3. Hard yellow rock, upper surface well defined, merging below into underlying chalk - 1 2. Dull white mealy chalk with lumps of hard Zone of I white chalk (Micraster Beds) - - - 14 Holaster planus. \ 1. Chalk jRocL—Haxd yellowish limestone with a layer of green-coated nodules at the top and many green and black grains, seen for -_____2 27 The contrast between the dull white tint and lumpy character of the Micraster Beds, and the whiteness, even fracture, and bedded character of the chalk above the upper rock bed is here very marked. — (A. J. J.-B.) 2. Exposures on the Dip -slope. By H. J. 0. White. The best sections in the inhers are those in the quarries opened on the northern slope of the Thames Valley, between Henley and Medmenham. Some account of their lithological features has been given in previous pubheations of the Geological Survey and elsewhere, but, so far as I am aware, no attempt to determine the limits of the Rolaster planus Zone in them has hitherto been made. The results of my own recent examination of these sections are not wholly satisfactory, for distinctive fossils are very scarce near the bottom of the zone, while the highest beds are in no case sufficiently accessible to enable one exactly to locate the junction with the overlying M. cortestudinariiim chalk. As Mr. Jukes-Browne has stated in the introduction to this chapter, the upper limit of this zone is unmarked by any persistent lithological feature. In a disused quarry at the_ lower lodge of Henley Park, and about a mile north of the town, the subjoined section is seen : — Zones of Micraster \ Ft. cortestiidinarium „ iin,-i x. ^^ -^i. a- i. ■ i ^ Wnite chalk, with many flints, m somewhat irregular courses ; a well-mai'ked flinty band, iron-stained in places, at the base. 3/icraster praicursor Rov/e - - - 12 and Ho taster plasms (junction probably between 1 and 3 ft. from base). tlPfEb CHAtk. 43 Zone of Holaster planus. 25^ It. 5, Irregularly blocky to lumpy and nodular Ft. white to greyish- white chalk, consisting of hard, ill-defined lumps in a firm to soft matrix. Some solid flint-nodules, disposed in more or less widely-open courses, and becoming notably scarcer downwards ; also scattered, small, globular flints, with thick, friable, white rinds. A more definite layer of flints at the base. Inoceramus cuvieri J. de C. Sow.; /. s/v'v Ostrea vesicularis Lam. ; 0. spp. ; Plicatula barroisi Peron ; Bimyodon nilssoni (Hag.); Spondylus latus (J. Sow.); S.spinosus (J. Sow.) ; BhynchoTiella plicatilis (J. Sow.) ; Ji. reedensis Eth. ; Terebratula carnea J. Sow. ; T. semiglohosa J. Sow.; Stoma- topora gracilis Edw. ; Serimla spji. ; (fyphosoma radiatum Sorig. ; Echino- corys scutatus Leske (gibbous and ovate forms) ; Holaster placenta Ag. ; Micraster cortestudinarium (Goldf.) ; M. prcecursor Rowe ; Ventriculites mamniillay-is T. Smith ; V. alcyonoides Mant. - 21 J 4. Chalk Rode. — Hard, yellowish, crystalline limestone, with grains of glauconite and layers of green-coated nodules, one of the latter occurring at the top. Upper limit clearly marked, but not the lower. Crooked, branching borings abundant. Heteroceras S2>. \Scaphites geinitzi d'Orb.; Cerithium sp. ; Pleurotomaria perspect iva (Mant.) ; Cuspidaria caudata Nilss. ; Ino- ceramus sp. ; Spondylus spinosus (J. Sow.) ; Teredo anvphisbana (Goldf.) ; Trapeziuvi trapezoidale (F. A. Roemer) ; Rhynclionella phcatilis (J. Sow.) ; Terebratula carnea J. Sow. ; Echinocorys scutatus Leske ; Ner- pula grantilata .J. de C. Sow. ; 2Iicraster sp. (casts of a small form); Parasmilia cen tralis (Mant.) ; Plocoscyphia convoluta T. Smith -_--__ 4 /3. Hard to firm, lumpy, greyish-white chalk, with a few small, angular, green con- cretions ; becomes irregularly blocky towards base. Inoceramus cuvieri J. de C. Sow. ; /. sp. ; Ostrea vesicularis Lam. ; Terebratida seiiii- flobosa J. Sow. ; Terebratulina striata )av. ; Blscoidea dixoni Forbes \_=D. minima] Micraster corbovis (Forbes) - 4J 2. Seam of grey marl, 1 to 3 ins. Inoceramus sp. (fragments). 1. White to greyish- white chalk; firm, harsh to the touch, and widely jointed (flaggy where weathered). Contains a thin seam of grey marl 1 ft. below top. Inoceramus sp. ; Ostrea s/). ; Spondylus spinosus (J. Sow.) ; Terebratulina lata Eth. ; Gidaris serrlfera Forbes ; Poros- phcBra globularis (PhUl.) - - seen 9 The examples of Micraster prcecursor found at many horizons between the base of bed (5) and the top of the flint band at the base of bed (6) are all of II. planus Zdne types, and a comparison of their features with those Zone of Terebratulina (top). 44 UPPER CRETACEOUS. of the tests of the same species obtained from beds at the junction of the //. jjlaiius and M. cortestudinarivmi Zones elsewhere leads me to think that the upper limit of the former zone in this section occurs between 22 and 24 ft. above the upper surface of the Chalk Rock. Tests with distinctly "sub-divided" areas — presumably from the middle or upper part of bed (6) — are found on the talus. I have met vsdth no " sutured " forms at a greater height than 3 ft. above the Rock. It may be mentioned that the example of Stoniatopora gracilis recorded from bed (5) i.-i attached to a cast of Micraster, at the upper surface of the Chalk Rock. Chalk Rock, about 3 ft. thick, is exposed at the top of the steep bush- grown talus in the old quarry north of Greenlands Telegraph Office, but I have seen no fossils in it. At the quarry north of Westfield Farm, to the west of Medmenham, where chalk was worked for building-stone in 1899, and is now burnt for lime, the foUovnng succession is exhibited :— Zones of Micraster CO ) -testudinarium and Ilolaster planus (lunction prob- ably 5 or 6 ft. above base of bed 8). Zone of Ilolaster 2}lanus. 9. White chalk with many bands of rather small flints. A conspicuous course of flints at the base - 10 ? 8. White chalk with fewer flints ; a well-marked course of flints at the base. Echinocorys scutatus Leske (gibbous form) Micraster inxecm-sor Rowe - - 12 1 7. White, irregularly-blocky to lumpy chalk (with an ill-defined nodular layer 8 in. from the top) passing down into a greyish and more nodular chalk vnth some thin marly part- ings. Flints — far apart in courses and scattered — are not uncommon near the top, but scarce towards the bottom. Small globular flints with friable rinds occur throughout. Inoceramus cuvieri J. de C. Sow. ; /. sp. ; Ostrea vesicularis Lamr ; 0. sp.; Spondylus latiis (J. Sow.) ; /S'. spinosus (J. Sow.) ; Shynchonella plicatilis {J . Sow.) ; Terebmtula carnea J. Sow. ; T. semiglohosa J. Sow. ; TerehratuliiM striata Dav. ; Serpulasp.; Bryozoa; Echinocorys scutatws Leske (gibbous, ovate, and other forms) ; Holaster placenta Ag. ; IT. planus (Mant.) ; Micraster cortestudinarium (Goldf.) ; M. prcBcursoi- Rowe ; Ventriculites sp. - - 17i 6. Chalk Rock : Hard, cream-coloured crystal- line limestone, with two well-marked and other less distinct layers of green-coated nodules. The junction with bed below is marked in some places by a joint-plane. Baculites bohemicus Fritsch and Schloen. ; Scaphites^ geinitzi d'Orb. ; Cerithiuin saimdersi Woods ; Plev/rotomaria per- spectiva, (Mant.) ; Avellana sp. ; Trochtts berocscirensis Woods ; 2'. schluteri Woods ; Turbo sp.; Area cf. galliennei d'Orb.; Spon- Mus latus (J. Sow.) ; Inoceramus sj>. ; Bhynchonella plicatilis (J. Sow.) ; R. reedensis Eth. ; Stoniatopora gracilis (M. Edw.) ; Terebratula carnea 3. Sow. ; T. semiglobosa J. Sow. ; Echinoco^i/s scutatus Leske ; Micraster praxursor Rowe (small) Echinoids, thin-tested,— seen only in section. Parasmilia centralis (Mant.) ; Ventriculites sp. - - 4 Zone of TereliratuUna (top). UPPER CHALK. 45 Ft. I 5. Hard, lumpy chalk, passing down into firm, massive chalk with fine, undulate, marly laminiE - - o.^ 4. Seam of grey marl ; 1 to 3 in. 3. Greyish-white, firm chalk, with a thin seam of grey marl at the base - - 1 2. Greyish, firm, massive chalk, becoming whiter downwards. Flints in thin lenticles and horned and finger-shaped nodules 13 1. Firm, white chalk - - seen for 3 The fossils found in beds (1-5) have already been mentioned (see above, p. 34). The beds have a slight dip to the south-east. The rate of intraformational change in the test-features of Minnster jwwcursor (and M. cortesfndirMrium) appears to be the same as in the Henley Park section. The highest test of Jficraster jyTcecwsm- obtained by me occurred about 19 ft. above the Chalk Rock. It is of the " moderately inflated " type. I think it unlikely that the upper limit of the Holaster planus Zone here is situated less than 22 ft. above the top of the rock. In his description of the J/, eortestvdinarmm Zone sections of Oxford- shire and Buckinghamshire, Mr. Jukes-Browne (Cret. Bocks of Britain, vol. iii, p. 216) quotes the following note by Mr. W. Hill : — " ' A quarry at Medmenham, north of the church, shows some 40 to 45 ft. of chalk, but the face is inaccessible except near the base. The lower 10 ft. consisted of lumpy chalk of irregular texture, and above this is a layer of large flints rather widely separated. The next 20 ft. contained many scattered flints and one prominent flint floor. The highest part consists of massive chalk with large rough flints in irregular layers.' " From the lumpy beds below the first well-marked flint course, 10 to 12- ft. above the floor of this pit, I have obtained: — Inoceramus cuvieri J. de 0. Sow.; /. sp.; Terehrntuta semiglobosa J. Sow.; Rhynchonella plicatilis (J. Sow.); Serjntla ilium Goldf. ; S. plana S. P. Woodw. ; Bourgweticrinus (columnal) ; Cidari.i xceptrifera Mant. ; Echinoeorys scutatus Leske (rather small gibbous and ovate forms) ; Metopaster parMnsoni (Forbes) ; Micraster 2^'>'c<''iriior Eowe ("slightly inflated" type, 5 and 12 ft. above floor of pit) Porosphoera globularis (Phill.) and Flocoscyphia convoluta (T. Smith). These lowest beds are, therefore, in the zone of H. jjlanus, and it is probable that the flint course at their top is a continuation of that .seen at the base of bed (8) in the section at the kiln, described above. Fragments of Chalk Rock were thrown out of a shallow well by the entrance to the quarry, and other pieces (probably nearly in situ) were formerly to be seen at the spring beside the Marlow road, a little to the south-east. On the south side of the Thames, debris of the Chalk Rock can be seen at many points in the banks of the Henley-Remenham-Aston lane, but there is no clear exposure of the limestone in position. There are remains of a shallow working on the outcrop of the rock north of Remenham Lodge. A good section of the upper part of the zone is shown in the pit east of Remenham Church. Since Mr. Jukes-Browne's Memoir on the Upper Chalk appeared (in 1904), this pit has been reworked for chalking the soil on the gravel-terrace just above, and the character of the beds can be better made out. 46 UPPER CBETACEOTTS. Zones of Jficraster cortes- fudinarium and Holastei' planus (junction is probably within 5 ft. of base of this bed). Gravel. Ft. 2. White chalk, rather soft at top, but becoming lumpy downwards, and containing ill-defined bands of harder, yellowish, lumpy and nodular chalk. Solid flints occur sparingly in open courses. The small globular flints, noticed in the preceding sections, are abundant, and there are some very thin seams of tabular flint. A conspicuous floor of tabular flint at the base. The following are from lower half of bed ; — PleurotomariapersjKctma (Mant.),/wocer- amus cuvieri J. de C. Sow., /. s/>., Upon- dylus spinosus (J. Sow.), Cidaris sceptrifera Mant., Echinocorys scutatus Leske (gibbons, ovate, and otlier forms), Holaster jda- renta Ag., Mkranter cortestiidinarium Goldf., J/, pi-amrsor Rowe, Plocoscyphia convoltita (T. Smith), Ventriculites infunai/juliforinis S. P. Woodw., V. mammillaris T. Smith- - about 18 Zone of Holaster 2>lanus. ( 1. Mixed blooky and lumpy white chalk, with undulate grey marly seams, passing down into a rough chalk, consisting of firm to hard nodules in a soft marly matrix. A few flints, scattered and in open courses. Fossils : the same species as in bed (2), with the following additions : — Corax sp., Ostrea hip2}opodiiim Nilss., Terehratula cariiea J. Sow., T. semiglobosa J. Sow., Frohoscina crassa (Rom.) var. elevata Greg., Serpula cincta Goldf., S. ]>lana S. P. Woodw., Bourgueticrinus, Pentacrinus, Parasmilia centralis (Mant.), Coscinopora quincuncialis (T. Smith)j Porosphcera globularis (Phill.) exposed 11 Micraster 2yroecursor is very abundant m bed (1), especially in a band 3 ft. from the top. The tests are mostly of the " feebly " to " moderately inflated " types ; " sutured " forms being— so far as I have seen — limited to the lower half of the bed. In bed (2) I have found only three examples of the species, all within 2 ft. of the tabular flint-seam at the bottom. Two of these are of upper H. planus Zone types, while the third approaches the "sub-divided" form of tne M. cortestudinarium Zone. Mr. H. L. Hawkins has one very broad test of M. ccyi-testudinariiim from a higher horizon. I infer that the junction of the two zones lies somewhere between 2 and 5 ft. above the base of bed (2). Holaster placenta is very common in both divisions of the section. With the exception of one example of Jficraster cortestudimariwni, some tests of Holaster placenta and Echinoc(yrys scutattis, a cast of Pleurotomaria pierspectiva, and some sponge-impres- sions, all the fossils above recorded were obtained from chalk which I refer to the zone of Holaster planus. In the Assendon Valley there are two good sections of chalk belonging to this zone. One of these is in the quarry at the back of the cottages rather more than a furlong south-east of Middle Assendon Saw Mill. The greater (and more fossiliferous) part of the chalk here is in the zone of M. cortestudinarium., but, as the beds about the upper limit of the H. planus Zone are easily accessible, it will be well to describe the section pn this page. It shows ; — UPPER CHALK. 47 Zone of Micraster cor- testudimirkiin. Ft. 1 3. White blocky chalk, with many courses of solid and spongeous flints (niostly the former), some layers of tabular flint, and many sub-parallel oblique veins of the same. The lowest persistent layer of tabular flint in the section is taken as the base of this division about 25 2. Irregularly-jointed white chalk, with scattered harder lumps of yellow tint (2 to 3 ft.), passing down into lumpy and nodular yellowish chalk (I to 1 ^ ft). There is an irregular course of solid flints IJ ft. from the top, and another, less distinct, at the base. Fossils from this division, and from the lowest third of that above, include : — Lamna a2>pendiculala (Ag.), Ptychodus mam- millaris Ag., Inoceiuiiivs /ironr/iiinrfi J. de C. Sow., /. ctuiieri .7. de C. Sow., Ostrea hijipo- podiiuit' Nilss., 0. sp., Spondylus spinosus (J. Sow.), Kiiigena lima (Defr.) (rare), Terebratula carnea 3. Sow., T. semiglohosa J. Sow., Tere- bratulina striata (Dav.), RliynxhonellajMcatilu (J. Sow.), Ottycltocella dejrressa ? Hag., Probos- ciiML i-adiolUvrmn (d'Orb.), Beptoceritites roxvei Greg., Serjiii/a ilium Goldf., '^'. gmxiialis var. serpentinus Schlotb., Boufffueticrinus, Aster- oidea, Fentacrinus, Cidaris scentrifera Mant., Echinocorys scutatus Leske (gibbous form), Holaster placenta Ag., H. pilwnns (Mant.), 'Micraster cortestudinariuni (Goldf.), J/. jn-oecursor Rowe, Plocoscyphia convoluta (T. ^ Smith), Ventriculites mammillaris T. Smith - 3^ 1. Lumpy and nodular yellow chalk, with harder bands and undulate marly partings. One of the hard bands, about 5 ft. from the top, is rich in remains of Holaster placenta and sponge casts. Nodular flints, mostly small and far apart in courses, and scattered. A few impersistent seams of tabular flint in the upper part. Inoceramus cavieri, I. sj)j>., Ostrea sp., Spon- dylus spinosris, Xhync/ionella plicatilis, Tere- bratula carnea, T. semiglobosa, Asteroidea, Cidaris scepitrifera, Holaster jilacenta, Micraster 2}r(Bcursor, Coscinopoi~a qumcuncialis, Ploco- scyphia convoluta, Porosjihcera globularis (PhiU.), Ventriculites 7-adiatus Mant. seen 17^ The Micrasters found up to within 18 in. of the flints at the base of bed (2) are of the " feebly " to " moderately inflated," //. planus Zone types. Those obtained at and above that horizon are all of the " sub-divided " and " strongly inflated " forms characteristic of the zone of M. cortestudinariuni. The beds have an apparent dip of 5 or 6 deg. to the north-west, and are broken by small faults. The Chalk Rock has been worked at this spot ' but it is no longer visible. In the western bank of Hollandridge Lane, and just within the adjoining field, at a spot rather less than three furlongs north-east of Pishill Church, there are some small and shallow excavations in the Chalk Rock, and in the lumpy, glauconitic beds immediately below it. In the beds below the rock I noticed only Terebratula carnea J. Sow. and chips of thin Inoceramus-shell. From the rock itself, and chiefly from 1 W. Whitaker, ' Geology of the London Basin ' (1872), p. 48, Zone of Holaster jilanus. \ 48 UPPER CEETACEOUS. the topmost layer of green nodules, -which is directly overlain by the thin rubbly soil, Mr. Treacher and I have obtained :— Griocerai ellipticumi (Mant.), Solariella gemmata (J. de C. Sow), TmtSo geinitsi Woods, 8pondylus latus (J. Sow.), RhyTwhormlla plicatilis (J. Sow.), S. reedensis Etn., Terebratula semiglobosa J. Sow., Jleptoceritites rowei Greg., Micraster sp. (casts of small form, common,] M. leskei), Parasmilia centralis ? (Mant.). Casts and moulds of gasteropods are fairly abundant, but most of them are too much decayed by soil-water to admit of identification. The Chalk Eock here forms a distinct terrace on the end of the Holland- ridge spur, the ground rising rather sharply across the edges of the very flinty M. cortestudinarium beds to the north. A small opening in the eastern bank of the lane in the lower part of the slope above this terrace shows greyish, lumpy chalk, with bits of thin Inoceramus and of Echinocorys, and probably belonging to the upper part of the 11. planus Zone. Similar chalk, with Terebratula carnea, has been worked just above the outcrop of the Chalk Eock by the roadside at Pishill Bank. The excava- tion is very small, and the chalk in a dirty and rubbly condition. In the Hambleden Valley I know of only one clear section of the B. planus beds, though the Chalk Eock may be seen in the banks and gutters of most of the roads which cross its outcrop, and projects through the talus in a degraded pit to the east of Calstrope, north of Hambleden. By the side of the road loading up from the hamlet of Pheasants Hill to Eockwell End, and close to the former place, there are two small pits. The higher and more north-eastern pit is in the if. cortestudinarium Zone, and will be described under the appropriate heading. The lower pit shows :— 2. Greyish-white, lumpy and nodular chalk (in a semi-rubbly con- Ft. dition), containing a few flints of the usual ff, planus Zone types. Inoceramus cuvieri J. de C. Sow., /. sp., Spondylus spinosus (J. Sow.), Terebratula carnea J. Sow., 2'. semiglobosa J. Sow., Mieraster corbovis Forbes (" sutured "), M. prcecursor Eowe (" sutured "), Coscinopora quincuncialia (T. Smith), Ventriculites inammillaris T. Smith -------_8 1. Chalh Eock. Hard, cream-coloured, massive limestone, with grains of glauconite and green-coated nodules.. Heteroceras sp., Solariella gemmata (.J. de C. Sow.), Rhynch- onella plicatilis (J. Sow.), Terebratula carnea, Parasmilia centralis (Mant.) - _____ exposed 2 Very little of the rock is visible. In 1905 it was being worked for road- metal. H. .1. O. W. The Zone of Micraster cortesludinarimn. By A. J. Jukes-Browne and H. J. Osborne White. This zone is not a very satisfactory sub-division from a strati- graphical point of view. In this part of England it does not present any distinctive lithological features, while its fauna is scanty, and does not seem to include any species that are absolutely restricted within the limits of the zone. Practically, it can only be separated from the zones above and below by the varietal mutations of the Micrasters— ■i.e., M. prcecursor and M. cortestudinarium. Mr. Osborne White has succeeded in collecting a sufficient number of specimens to enable him to recognise the lower limit of the zone where it is exposed ; but he has not been able to ascertain its exact upper boundary at UPPER CHALK. 49 any locality, for exposures at this horizon are few and fossils are rare. The lower beds of this zone are exposed in most of the quarries where the Chalk Rock is seen, but exposures of the higher part are less frequent. The lower beds, which may be -about 20 ft. thick, consist for the most part of compact firm white chalk; but there are sometimes beds of lumpy, and even of rough, nodular chalk, which weather to a yellowish tint on the surface. Flints occur in layers of large solid nodules, black inside, with thin rinds. The higher beds, which may be 30 ft. thick, consist of soft white blocky chalk, in which flints are very numerous, occurring both in layers and scattered through the mass. The majority of them are spongeous and cavernous, and small globose flmts (often hollow) are very common ; continuous seams and layers are also frequent. A. J. J.-B. Along the escarpment of the Chilterns the lowest beds of this zone are poorly exposed in the upper part of the degraded Chalk Rock quarry, at Chinnor Hill (p. 41), where the follow- ing fossils were collected by Messrs. Chatwin and Withers : — Ivoceramus sp., Ostrea vesicularis Lam., Pecten cretoaus Defr., Serpula fiuctuata J. de C. Sow., S. ilium Goldf, Micraater prcBCuraor Rowe, Ventriculitea sp. Higher beds are exposed m a road-side pit E. of Manor Farm, on Chinnor Hill; the chalk contains regular courses of solid and spongeous flint- nodules, and some layers and veins of tabular flint. Here Messrs. Withers and Chatwin obtained Dinfiyodon nilssoni (Hag.), Spondylua lafjua (J. Sow.), Idmonea alipea Greg., Proboacina radiolitorwm (d'Orb.), Holaster placenta Ag., Micraater cortestu- dinarium (Goldf), Ecliinocorys scutatus Leske, Serpula ilium Goldf, S. fiuctuata J. de C. Sow., S. plana S. Woodw. The single example of M. cortestudinarium found is of a type characteristic of beds about the junction of the M. cortestudina- rium and M. coranguinum Zones. The horizon at which it occurred is estimated by Messrs. Withers and Chatwin to be about 20 ft. above the top of the Hoi planus Zone. The best sections occur in the neighbourhood of Henley, and some of these have already been described (see pp. 42 to 47). To the south of Bix Eectory, west of Middle Assendon, there is a little opening in white chalk with many spongeous flints, and a prominent layer of carious tabular flint. Here I have noticed : — Inoceramus cuvieri J. de C, Sow., Ostrea sp,, Bhynchonella reedensis Eth.. Asteroid ossicles, Gidaris clawigera Konig, Echinocorys scutatus Leske (a tall, gibbous form, and portions of a tmn test), Pentacrinus, and Pharetrospcmgia strahani. This pit is probably 50 to 60 ft. higher than the outcrop of the Chalk Rock about one furlong distant to the north-east. In a wood by the lane leading from Mill End to Rotten Row, and rather less than half a mile from the former place, a quarry shows about 50 ft. of white chalk with many courses of carious and solid flints, and some layers of tabular flint near the bottom. Small globular flints abound between 10 and 15 ft. above the floor of the pit at the north-western end. Some disturbance, which appears to be of a strictly local order, has given the beds the rather high dip of 10° to the south-west. After Inoceramus 10322. E 50 UPPEE CRETACEOUS. cvAderi, the commonest fossil in the lower beds is Cidouris cUmigera. Examples of Micraster prmcwrsor Eowe, of forms characteristic of the Jf. cartestvdinariwm zone, were found at 7J and 16 ft. above the lowest flint- course seen in the section. The other fossils found by me in the lowest third of the section are : — Inoceramus involutus J. de C. Sow., Lima hoperi (J. Sow.), Ostrea sp., Spondylus latus (J. Sow.), Bryozoa, Serpula plana S. P. Woodw., S. ciTicta Goldf., S. pentamgulata S. Woodw., Gidaris serrifera Forbes, Echinocorys scutatus Leske (gibbous form, large), Meto- paster pa/rkinsoni (Forbes), Plinthosella squamosa Zitt., Porosphmra globula/ris (Phill.). The highest beds^ which are out of reach, are probably in the zone of Micraster corangmniim. A small but fossiliferous section of the lowest beds of the M. cortes- tudinarium Zone is seen in the higher of the two pits near Pheasants Hill, before mentioned (p. 48). This is about 13 ft. deep, and shows irregularly- jointed, greyish- white chalk, with a course of rather small _ solid flints near the top and bottom, and some scattered flints between. Six to seven feet above the floor of the pit there is a band of harder, yellowish, lumpy and nodular chalk, with impressions of sponges. The fossils found are ; — Inoceramus cuvieri J. de C. Sow. ; Inoc. sp., Ostrea hijmopodiwm 1 NUss. ; Spondylus spinosus J. Sow. ; Terebratvla carnea J. Sow. j Thecidiwm wetherelli % Morris ; Berenicea sp., Stornatp- fora gracilis (M. Edw.) ; Serpvla plana S. P. Woodw. ^ Gidaris serrifera 'orbes ; Echinocorys (bits), Micraster cortestudinarium, (Goldf.) ; M. prcecu/rsor Eowe ; Plinthosella squamosa Zitt. ; Plocoscyphia convolwta (T. Smith) ; Ventriculites ma/mmillwris T. Smith. The Micrasters found occurred between 4 and 8 ft. above the floor of the pit, which is probably rather more than 20 ft. higher than the top of the Chalk Rock exposed in the other excavation, a short distance to the south-west. Three furlongs east of Eose Hill, and about seven furlongs south-by-east of Medmenham Abbey, there is a field-pit, 18 ft. deep, in white chalk abounding in spongeous and tabular flints. The beds dip about 5° to the south-east. A little hard, yellow, lumpy chalk is seen near the floor of the working. The following forms have been found here : — Inoceramus cuvieri, Inoc. sp., Spondylus latus (J. Sow.) ; Rhynchonella reedensis Eth. : Terebrdtula semiglohosa J. Sow. ; Terebratulina striata Dav. ; Berenicea sp., Gribrilina sp., Entalophora virgula (Hag.) ; Eschara sp., Homaeosoten aculeatus d'Orb. ; Membranipora navicularis Eeuss ; Memhra/rdporq, sp., Micropora hippocrepis Goldf. ; Nodelea durobrivensis Greg. : Onyehocdla sp., Proboscina fasciculata (Reuss) ; Reptoceritites rowei Greg. ; Repto- multisparsa sp., Siphoniotyphlus tenuis (Hag.) ; Asteroid ossicles, Bov/rgueticrinus, Gida/ris hirudo Sorig. ; Echinocorys scutatus Leske (gibbous form) ; Helicodiadema fragile (Wilt.) ; Micraster (hits) • Goscino- pora sp. ; D