UC-NRLF B M 173 MOIRS OF THE GEOLOGICAL SURVEY, ENGLAND AND WALES. EXPLANATION OF SPECIAL OXFOED SHEET. THE GEOLOGY OF THE COUNTRY AROUND OXFOKJ3. BY T. I. POCOCK, M.A. WITH CONTRIBUTIONS BY H. B. WOODWARD, F.E.S., AND G. W. LAMPLUGH, F.R.S. PUBLISHED BY ORDER OF THE LORDS COMMISSIONERS OF HIS MAJESTY'S TREASURT. LONDON: PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE BY WYMAN AND SONS, LIMITED, 'FETTER LANE, B.C. ^And to be purchased from E. STANFORD, 12, 13, AND 14, LONG ACRE, LONDON; W. & A. K. JOHNSTON, LTD., 2, ST. ANDREW SQUARE, EDINBURGH ; HODGES, FIGGIS, AND CO., 104, 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 and Threepence. BERKELEY LIBRARY UNIVERSITY OF CALIFORNIA EARTH SCIENCES LIBRARY EXCHANGE MEMOIRS OF THE GEOLOGICAL SURVEY, ENGLAND AND WALES. EXPLANATION OF SPECIAL OXFORD SHEET, THE GEOLOGY OF THE COUNTRY AROUND OXFORD. BY T. I. POCOCK, M.A. WITH CONTRIBUTIONS BY H. B. WOODWARD, F.R.S., AND G. W. LAMPLUGH, F.R.S. PUBLISHED BY ORDER OF THE LORDS COMMISSIONERS OF HIS MAJESTY'S TREASURY. LONDON: PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE BY WYMAN AND SONS, LIMITED, TETTER LANE, B.C. And to be purchased from E. STANFORD, 12, 13, AND 14, LONG ACRE, LONDON; W. & A. K. JOHNSTON, LTD., 2, ST. ANDREW SQUARE, EDINBURGH ; HODGES, FIGGIS, AND CO., 104, 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 and Threepence. AM ' U/L- c* 08 PKEFACE. THE original geological survey of the area included in the new Oxford Sheet was carried out during the years 1857 to 1863 by Messrs. E. Hull, H. Bauerrnan, W. Whitaker, T. R. Polwhele, and A. H. Green. Their work was published on the Old Series Sheets 13, 45 S.W. and 45 S.E., and in accompanying Explanatory Memoirs. Some revisions at Islip (45 S.E.) were made in 1867 by H. W. Bristow. The re-survey on the six-inch scale was commenced in 1896 by the late Mr. John Hopwood Blake and continued until the time of his death early in 1901. It was aftsrwards decided to complete the field-work over an area sufficient for the publica- tion of a map with Oxford^as a centre, and Mr. T. I. Pocock was deputed to do this work under the superintendence of Mr. H. B. Woodward, who personally surveyed portions of the country near Wheatley. Aid was also given in the examination and revision of the Lower Cretaceous areas by Mr. G. W. Lamplugh, whose observations have led to a separation of the freshwater Shotover Sands, now regarded as of Wealden age, from the marine Lower Greensand with which they were formerly grouped by the Geological Survey. The preparation of the Memoir was entrusted to Mr. Pocock, who has dealt very fully with the Pleistocene and Recent deposits, to which he has given especial attention. The chapters dealing with the Jurassic Rocks have been partly written by Mr. Woodward, those on the Lower Cretaceous rocks have been contributed by Mr. Lamplugh, and that on the Upper Cretaceous rocks is based on the published observations of Mr. Jukes-Browne. Owing to the resignation of Mr. Pocock in ' 1906, a larger share of the work than was expected has fallen to Mr. Woodward, who has written the Introductory Chapter and prepared the Appendix.^ We are indebted to Mr. T. Codrington for a section of the railway-cutting near Horsepath, and to Mr. W. W. Fisher, Mr. R. H. Tiddeman, of Oxford, and Mr. George Winship. of Abingdon, for records of well-borings. The fossils collected during the progress of the geological survey have been named in the Palseontological Department. A list of the six-inch geological maps with the authors and dates of survey is appended. MS. copies of these maps are deposited in the Office for public reference. J. J. H. TEALL, Geological Survey Office, Director, 28, Jermyn Street, London, 5th November, 1907, IV LIST OF SIX-INCH GEOLOGICAL MAPS. BERKSHIRE. 6 S.W. (Oxford 39 S.W.). Bessels Leigh. By J. H. Blake, 1899, and T. I. Pocock, 1904. 9 N.W. Hinton Waldrisb, Kingston Bagpuize. By J. H. Blake, 1899. N.E. Fyfield, Marcham. By J. H. Blake, 1899,' and T. I. Pocock, 1905. BUCKINGHAMSHIRE. 26 S.E. (Oxford 28 S.E.). Muswell Hill. By H. B. Woodward, G. W Lamplugh, and T. I. Pocock, 1904-05. S.W. (Oxford 28 S.W.). Ot Moor. By T. I. Pocock, 1905. 27 S.W. (Oxford 29 S.W.). Brill. By H. B. Woodward and G. W. Lamplugh, 1904-05. 31 N.E. (Oxford 34 N.E.). Oakley. By H. B. Woodward and T. I. Pocock, 1904-05. S.E. (Oxford 34 S.E. ). Worminghall, Waterperry. By H. B. Woodward, 1904-05. 32 N.W. (Oxford 35 N.W.). Ixhill. By H. B. Woodward, 1905. S.W. (Oxford 35 S.W.). Little Ickford. By H. B. Woodward, 1905. OXFORDSHIRE. 26 S.W. Wilcote, North Leigh. By T. I. Pocock, 1904. S.E. Bladon, Church Hanborough. By T. I. Pocock, 1904. 27 S.W. Begbroke, Kidlington. By T. I. Pocock, 1904. S.E. Islip, Oddington. By T. L Pocock, 1905. 32 N.W. Eynsham Hall. By T. I. Pocock, 1904. N.E. (Berks 1 N.E.) . Eynsham, Cassington. By T. I. Pocock, 1904. S.W. South Leigh, Hard wick. By T. I. Pocock, 1904. S.E. (Berks 1 S.E.). Swinford. By J. H. Blake, 1897, and T.I. Pocock, 1904. 33 N.W. (Berks 2 N.W.). Yarnton. By J. H. Blake, 1899, and T. I. Pocock, 1904. N.E. Woodeaton, Elsfield. By J. H. Blake, 1898, and T. I. Pocock, 1904. S.W. (Berks 2 S.W.). Wytham and Binsey. By J. H. Blake, 1898, and T. I. Pocock, 1904. S.E. N. Oxford and Headington. By J. H. Blake, 1898, and T. I. Pocock, 1905. 34 N.W. Stanton St. John, Beckley, and Studley. By T. I. Pocock, 1904-05. S.W. Forest Hill and Holton." By J. H. Blake, 1897 ; H. B. Woodwapd, G. W. Lamplugh, and T. I. Pocock, 1904-05. 38 N.W. Brighthampton and Standlake. By J. H. Blake, 1897, and T. I. Pocock, 1904. N.E. (Berks 5 N.E.). Stanton Harcourt, Northmoor and Eaton. By J. H. Blake, 1897, and T. I. Pocock, 1904. S.W. (Berks 5 S.W.). Shifford. By T. I. Pocock, 1904. S.E. (Berks 5 S.E.). Appleton. By J. H. Blake, 1897, and T. I. Pocock, 1904. 39 N.W. (Berks 6 N.W.). Cumnor. By J. H. Blake, 1897, and T.I. Pocock, 1904. N.E. (Berks 6 N.E.). S. Oxford, Cowley. * By J. H. Blake, 1897, and T. I. Pocock, 1904. S.E. (Berks 6 S.E. ). Littlemore, Sandford-on-Thames. By J. H. Blake, 1899, and T. I. Pocock, 1905. 40 N.W. Wheatley, Horsepath. By J. H. Blake, 1897, H. B. Woodward and G. W. Lamplugh, 1904. N.E. Waterstock, Tiddington. By J. H. Blake, 1898, and H. B. Wood- ward, 1904-05. S.W. Garsington, Denton and Toot Baldon. By J. H. Blake, 1897, and H. B. Wood ward, 1907. S.E. Great Milton, Great Haseley. By J. H. Blake, 1897, and H. B. Woodward, 1905. 41 N.W. Albury. By A. J. Jukes-Browne, 1885, and H. B. Woodward, 1905. S.W. Latchford. By J. H. Blake, 1898, and H. B. Woodward, 1905. 45 N.W. (Berks 10 N.W.). Abingdon. By J. H. Blake, 1896, and T. I. Pocock, 1905. N.E. (Berks 10 N.E.\ Nuneham Gourtenay. By A. J. Jukes-Browne, 1887, J. H. Blake, 1897, T.I. Pocock, 1905, and H. B. Woodward, 1907. 46 N.W. March Baldon. By A. J. Jukes-Browne, 1886, J. H. Blake, 1899, and H. B. Woodward, 1907. N;E. Stadhampton. By J. H. Blake, 1899. 47 N.W, Easington. By A, J. Jukes-Browne, 1886, CONTENTS. PAGE PREFACE BY THE DIRECTOR iii. CHAPTER I. INTRODUCTION ... 1 CHAPTER II. LOWER OOLITES. Inferior Oolite Upper Estuarine Series Great Oolite 7Forest Marble Oornbrash ... ... ... ... ... ... ... 10 CHAPTER III. MIDDLE OOLITES. Oxford Clay and Kellaways Beds 23 CHAPTER IV. MIDDLE OOLITES (continued}. Corallian ,. ... 26 CHAPTER V. UPPER OOLITES. Kimeridge Clay 46 CHAPTER VI. UPPER OOLITES (continued). Portland Beds Ptirbeck Beds . rt 50 CHAPTER VII. LOWER CRETACEOUS. Shotover Sands 64 CHAPTER VIII. LOWER CRETACEOUS (continued). Lower Greensand 75 CHAPTER IX. UPPER CRETACEOUS. Gault Upper Greensand 79 CHAPTER X. SUPERFICIAL DEPOSITS PLEISTOCENE AND KECENT. Alluvium Valley Gravels 81 CHAPTER XI. DEVELOPMENT OF THE RIVER VALLEYS 106 CHAPTER XII. ECONOMIC GEOLOGY. Water Supply Building Stone Lime- -Road Metal Sand Brickearth Fuller's EarthOchre 120 APPENDIX. LIST OF PRINCIPAL WORKS ON THE GEOLOGY OF THE DISTRICT 133 INDEX 137 9813. 600 Wt. 3815. 1/08. Wy. & 8. * V % .^ INTRODUCTION. Geological Formations. The geological formations represented at the surface are as follows : RECENT AND PLEISTOCENE UPPER CRETACEOUS LOWER CRETACEOUS Upper Oolitic Middle Oolitic Lower Oolitic [ Alluvium I Brickearth | Valley gravel ... [ Plateau gravel Upper Greensand Gault (clay) Lower Greensand Wealden Shotover Sands (with clay, and ironstone) C Purbeck Beds (clay and limestone) J Portland Beds f Limes tone and sands 3 \SandsandHartwellClay... [Kimeridge Clay f ( Coral Rag and^l ^ | Corallian I Oolite ! Ampthill U n , ; Beds 1 Calcareous grit f Clay j D1 j ^ and sands J ) | Oxford Clay and Kellaways Beds (sands and I clay) f Cornbrash (limestone) 9 to j Forest Marble (clay and limestone) ... 12 to a 3 H K O *j ^\ ?^ ^ ^^ PQ * j* If * 3 Ft. in. Ft. in. Ft. in. Ft. in. Ft. Ft. in. Alluvium ... Gravel " '.'* I 15 30 '} 11 Oxford Clay and Kellaways Beds ... .. . 258 210 265 2 Cornbrash 17 17 O^i 13 Forest Marble ... 43 26 6 32 8 | 20 6 Great Oolite Upper Estuarine Series 62 6^ 141 6 | 96 i 88 f* 28 6 | 155 s 141 6 39 Inferior Oolite ... 27*" 8 30 35 6 16 4J 7 Upper Lias Middle Lias Lower Lias 81 6} 98 IV 447 43 55 6+| 14 6 170 6 + 17"'o :! 233 0+ Rhsetic and New Red Marl 466 11 ... ... Coal Measures ... 226 ... ... ... ... ... 1410 270 633 439 6 420 467 1 Read before the Ashmolean Society, 1876. 2 H. B. Woodward, " Jurassic Rocks of Britain," vol. iii. " Lias of Eng- land and Wales," p. 269. 3 F. A. Bather, Quart. Journ. Geol. Soc., xlii., p. 144. 4 The details of the Burford boring were given in "Memoir 071 Jurassic Rocks of Britain," vol. iv.. pp. 303, 304 ; those of Witney, Wytham, and St. Clement's in vols. iv., pp. 372, 513, v., pp. 42, 43 ; and an abstract of the City Brewery boring, Oxford, in the " Summary of Progress" for 1898. p. 139. 5 The thickness of rock-beds passed through has usually been given as 135 ft., but Prestwich ascertained at the St. Clement's Brewery "that the depth was 155 ft. tteol. Mag., 1876, pp. 238, 239. INTRODUCTION. 5 Physical Features and Soils. The strike of the Lower Oolites is from north-east to south- west, with a gentle south-easterly inclination of the strata. This is modified locally by the faulted anticline which brings in the Cornbrash and other rocks at Islip. With this excep- tion the general strike and dip are maintained not only in the succeeding Oolitic strata, but in the Lower and Upper Cretaceous rocks which have transgressed unconformably on to some of the older divisions. The N.W. and S.E. faults that accompany the anticline disturbance at Islip, are con- tinued by Forest Hill to Wheatley, and are probably con- nected with the inlying tract of Kimeridge Clay at Great Milton, and with the faulted tract of Shotover Sands at Great Haseley. The Lower Oolites rise to nearly 450 feet in the north- western part of the area, and they lie a little over 30 feet beneath O.D. at Oxford, about eleven miles distant. The features which characterise the outcrops of the successive strata are well marked, and at the same time, owing to the irregularities in the distribution of the over- lapping Cretaceous strata, and the varied influences on the agents of denudation, considerable diversity of scenery has resulted. The nature of the soil, as might be expected, is very change- able. The area comes within that described by Arthur Young 1 under two broad divisions, namely : (1) The district of the Stonebrash and (2) that of Miscellaneous loams ; and the greater part of it was included by him in this mixed group. The former would include only the limited areas of the Lower Oolites ; the latter would include the great clay-tracts and the impersistent band of Corallian limestones, belonging to the Middle and Upper Oolites, with the outlying masses of Portland Beds, the Cretaceous tracts, and the larger areas of Valley drift. Thus grouped a remarkable diversity of soil is encountered, and of land in arable cultivation and pasture, including much good dairy-land and tracts of woodland. In a general description where no attempt can be made to deal in detail with the soils, the above grouping is convenient. The Stonebrash region commences with the Great Oolite of the country bordering the Evenlode above Hanborough. It there forms the margin of a tract of fairly level upland that descends steeply to the river. Stone-fences divide the fields, and the soil is a brashy or rubbly loam or clay. Fragments of ironstone were met with in the soil bordering the Alluvium, on the spur east of Ashford Bridge ; and it was at first thought likely that the Fawler iron-ore, beneath a thin representative of Upper Lias, might occur there below the Inferior Oolite. Some excavations were made, and these proved that Yalley gravel fringed the Oolite at the southern end of this spur. (See p. 10.) i "View of the Agriculture of Oxfordshire," 1809, p. 3. See also article " On the Farming of Oxfordshire," by Clare Sewell Read, Journ. Hoy. Agric. Soc. t vol. xv., 1854, p. 189. 6 INTRODUCTION. The area occupied by Oxford Clay is for the most part gently undulating ground, with here and there a low escarp- ment, above the Cornbrash, where the sandy strata of the Kellaways Beds are developed. A good deal of the ground is low-lying and almost Alluvial in aspect; the soil is a stiff and heavy clay, except where lightened by thin coverings of gravel or downwashes from the scarps of Lower Calcareous Grit ; and the slopes are damp and rushy in places. The hedgerows, as a rule, are well-timbered, with oak and elm, ash, willow, and poplar. The Corallian Beds yield a variable soil, for the most part light and brashy. Much of it is a rich, friable, sandy loam, generally brown, but sometimes of red colour. The ground is mostly under cultivation for corn and roots, and to some extent as meadow-land, but there are occasional rabbit-warrens on the sandy areas of the Lower Calcareous Grit. An analysis of soil taken from Little Hill field, Wick Farm, Headington, has been made at Reading College. The soil, which lies on the Calcareous Grit, is described as a light sandy loam, 6 to 9 inches deep, and very free from stones. " The nitrogen and organic matter of this soil are very low, but there is a good supply of phosphoric acid and potash." The subsoil is " free sand, with the rock of the Calcareous Grit in many cases coming near the surface. Although the underlying rock contains limo, the soil is, as a rule, poor in lime, except where the rock comes near the surface." 1 Near Littlemore the Upper Corallian Beds are very argillaceous, and the soil is comparatively stiff. The grass- lands on the Corallian clays in the area north-east of Wheatley are generally good, modified as the soil is here and there with thin gravelly patches ; indeed, the higher tracts of meadow T -land near Ickford, Waterperry, and Holton are regarded as among the best grazing and dairy-lands in the western part of the Yale of Aylesbury. The lower-lying ground at Ickford Village, as well as the Alluvial flats, are liable to floods, portions of the village being flooded in 1894, and again in June, 1903. The Upper Oolites, consisting of the Kimeridge, Portland, and Purbeck divisions, occupy a smaller superficial area than the Corallian, as they are partially concealed by the overlap of Cretaceous strata. The Kimeridge Clay, overlain directly by Gault, occupies the northern part of the Yale of White Horse, and passes into our region along the Ock Valley at Marcham and Abingdon. Thence it extends to Radley, and rises north- wards on the flanks of Boars and Cumnor Hills, where it is cut off by the deep valley of Botley. On the other side of the river it forms the banks below the sands of Nuneham Park, and rising eastward completely encircles the vShotover Hills, passes into the Thame Yallev, and spreads out north- ward, to form the base of Brill and Muswell Hills. Notice- able landslips of recent date may be seen along the slopes of Kimeridge Clay, south-west of Wheatley railway-station ; 1 "First Ann. Rep. on the Soils of Dorset, &c./'Ly D. A. Gilchiist and C. M. Luxmore. 1899, pp. 26, 27, 40. INTRODUCTION. 11. Corallian Beds. 10. Oxfordian Beds. 9. Cornbrash. 8. Forest Marble. 41 II SI o h * ^ ^ 5 ^ a 'S 2 > ^ D INTRODUCTION. and there are evidences of older slips on Shotover Hill and Red Hill. It forms a stiff clay soil that is locally improved by downwashes from bordering hills of Portland Beds and Shotover Sands. Along the eastern tract alone are remnants of the Portland and Purbeck strata preserved. Eesting on a foundation of clay, and themselves supporting sands and clays of the Cretaceous system, these strata form groups of isolated hills and winding ridges trenched by many combes, and thus they stand out in bold relief from the vales of Jurassic clay and Gault around them. They form the outliers of Shotover (516 feet) and Brill (over 600 feet), and the hills about Great Milton. The Portland Beds yield a calcareous and sandy soil, much of it under arable cultivation. Between Great and Littlo Milton a considerable area of fairly open country is occupied by these strata. Milton field was described by A. Young as " one of the finest soils I have met with in the county ; a dry, sound, friable loam on gravel [rubble] convertible land, as they call it in Oxfordshire." 1 The Purbeck division has only been detected in a few places, and is but a few feet thick. The Shotover Beds and Lower Greensand yield a variety of soils, the texture, composition, and colour alike differing. The higher beds of ironsand form a red ferruginous earthy soil, as on Red Hill and parts of Shotover Hill. Loamy or clayey beds form the surface in places, near the windmill at Great Milton, and between Great Haseley and Little Haseley. The Gault which forms the slopes near Latchford, gives rise to a stiff clay-soil. The land is mostly under grass. On the Alluvial areas of the Yale of Isis, between Eynsham and Standlake, where the low-lying gravels are composed largely of rolled fragments of limestone, there is a reddish- brown brashy soil not unlike that of the Cornbrash. This is fairly dry considering the situation, and furnishes good corn-land. . An analysis of a sample of soil from Stanton Harcourt made in 1870 by Dr. A. Yoeleker, showed 32 per cent, of carbonate of lime. He described the soil as a clay-marl with a gravelly subsoil, and considered that it should " be used as arable rather than as meadow land." Some of the gravelly tracts in this neighbourhood, at Standlake, Northmoor, and Eynsham, were liable to serious floods, especially from the Windrush, but considerable protection has been afforded by embankments made during 1866-67. 2 Elsewhere the Alluvial meadows form excellent grazing grounds. The industries are chiefly agricultural, but they include stone-quarrying, lime-burning, and brickmaking for local purposes. The city of Oxford stands at the southern extremity of a long " Agriculture of Oxfordshire," 1809, p. 8. S. B. L. Druce, Journ, Roy.Aqric. Soc., ser. 2, vol. vi., 1870, p. 373. INTRODUCTION. 9 insulated tract mostly of Oxford Clay, capped by gravel, and surrounded by Alluvium. This tract extends from Kidlington on the north to the confluence of the Thames and Cherwell, above which is the bank of gravel on which the city is placed. Of the history of the occupation of the site we learn from Mr. James Parker that there is no evidence of any settlement of importance in British times, and the site was not traversed by any of the old Roman ways; that the founding of a nunnery by St. Frideswide about the year 727 " upon the spot now occupied by Christ Church," is legendary, although not improbable; but that nothing about Oxford is known with certainty prior to " A.D. 912, when King Edward the Elder took possession of the place." The name then recorded of Oanaforda is the earliest form of spelling, and " distinctly represents c the ford of the Oxen ' " ; but it has been held " that the name is a corruption of Ouse-ford or Ousen-ford," that is, " the ford over the river." On this subject authorities are not agreed. ; ' The earliest foundation provided for scholastic purposes in Oxford " dates from 1249, and is represented by University College ; l but Merton College claims to have been the first to establish the college system in 1274. 2 From that date, at any rate, the city became a seat of learning; and in due course geology found a place in the curriculum. John Phillips 3 has recorded that "the Museums of the University of Oxford contain the oldest public collection ever formed in the British Isles for the illustration of natural history, antiquities, and archaeology." The Ashmolean Museum, when completed in 1683, was placed in charge of Robert Plot, and afterwards of Edward Lhwyd, to both of whom we are indebted for early knowledge of the fossil organic remains of the neighbourhood of Oxford. About a century later, systematic investigation of the strata was commenced by William- Smith, who published geological maps of the three counties, portions of which are included in our district. The study of geology was first taught by Dr. John Kidd, the Professor of Chemistry, who may be said to have inspired W. D. Conybeare, William Buckland, and others. To them, to Fitton, John Phillips, Dr. J. F. Whiteaves, J. F. Blake, Mr. W. H. Hudleston, Mr. James Parker, and to the more recent observations of Mr. A. Morley Davies, our knowledge of the local geology, apart from the work of the earlier Geological Survey, is largely due. 4 i James Parker, " The Early History of Oxford," 1885, pp. 2, 53, 63, 348, 351. "Memorials of Merton College," by the Hon. G. C. Brodrick, 1885, p. 6. 3 See Phillips, " Geology of Oxford," &c., 1871, p. 1 ; and W. J. Sollas, " The Influence of Oxford on the History of Geology," Science Progress, viii., 1898, p. 23, reprinted in " The Age of the Earth and other Geological Studies," 1905, p. 219. 4 See the Director's Preface and the Appendix. 10 LOWER OOLITES. CHAPTER II. LOWER OOLITIC ROCKS. BY T. I. TOCOCK. Along the banks of the Evenlode, above the point where it enters the Oxford plain, the oldest rocks in the neigh- bourhood come to the surface. They rise with gentle inclina- tion from beneath the Oxford Clay in nearly the same direc- tion as the valley, but at a slightly greater angle, so that as they are traced up-stream successively lower strata are brought up. Though much reduced in thickness, and wanting several of the subdivisions, the Lower Oolitic series is the same as that which, further west, forms the fine escarpment of the Cottes- wold Hills. The main divisions represented in the area are as follows: f Cornbrash. ~ ,., . Forest Marble. Great Oolite Series Great Oolite I Upper Estuarine Series. Inferior Oolite. INFERIOB OOLITE. Only the upper portion of the Inferior Oolite is present, viz. the zone of Parkinsonia Parkinsoni, the lower zones being overlapped in succession as the formation is followed east- ward from the Cotteswold escarpment. 1 Unfortunately no good sections are exposed within the limits of the map. The sections on the scarp near Stonesfield Ford, to the north of the area, showed the two upper subdivisions of the Inferior Oolite: Chipping Norton Limestone Hard, fine-grained oolitic limestone. Olypeus Grit Rubbly oolitic and pisolitic limestone, with Clypeus Ploti, Pholadomya, Trigonia, Pleuromya, and RhynchoneUa. The outcrops within the map are on either side of the river by Ash- ford Mill, that on the right bank being brought up by a fault running southward to Holly Court Farm, that on the left by a sharp upfold or a fault. The latter was proved by digging a small pit in the field next the railway, which showed ironshot oolite of the Clypeus Grit division one foot below the surface. There was also some indication in the surface soil of the buff limestone, known as the Chipping Norton Limestone. Pro- bably the whole series crops out low down on the valley slopes, the bed of the river being upon Lias, for at Fawler the maximum thickness is 37 feet, and it is most likely less here. i E. Hull, Quart. Journ. Geol. Soc., xvi., p. 72; and H. B. Woodward, "Jurassic Rocks of Britain," iv., p. 150. INFERIOR OOLITE. 11 Cl^peus Grit. Inferior f Oolite. 1 Lower Beds of - Ragstone. At Fawler, a little to the north-west of our district, the section is given as follows by Mr. Woodward 1 : Ft. in. f Oolitic limestone of variable texture, j with occasional marly layers. Few fossils occur; but Pholadomya and ne ' I Echinoids may be found 12 to 15 f Rubbly oolitic marls and coarse marly oolites, with Clypeus Ploti, Parkin- sonia Parkinsoni, Pholodomya Deivalquei, Terebratula globata, &c. 8 to 12 f Marly limestones 5 to 6 j Coarse oolitic, and almost pisolitie, ") limestones, with GeruilUa, Isocar- dia, Lima gibbosa, Modiola Lons- dalei, Pleuromya, Pecten vagans, Rhynchonella concinna, R. obsoleta, R. varians, Serpula, &c. ... ... ^ Hard iron-shot limestone, with pebbly ! layer at base ; Corals, Echinobrissus \ clunicularis, Rhynchonella spinosa, \ Terebratula global a, and T. maxillata \ (smooth form) } Upper Lias Blue Clay. From the basement-bed (above the Upper Lias Clay) Mr. E. A. Walford obtained small blocks of limestone covered with Plicatulce and pierced with Lithodomi\ and he recorded the occurrence of Trigonia products, T. angulata, &c. The section indicates that the upper beds of the Inferior Oolite overlap the lower beds and rest directly on the Upper Lias, as is also the case near Burford. The Chipping Norton Limestone, described under this name in 1878 by Mr. W. H. Hudleston, 2 forms the highest part of the Inferior Oolite in this district. Nevertheless, as pointed out by Mr. Walford and others, the fossils recorded from it present Bathonian characters. The superincumbent deposits are variable, and comprise clays and marls with Ostrea aeuminata J. Sow., 0. Soiverbyi M. & L., Nerincea Eudesi M. & L., &c., and representatives of the Stonesfield Slate. These strata may be looked upon as more or less equivalent to the Fuller's Earth (Fullonian) formation on the one hand, and the Upper Estuarine Series on the other. GREAT OOLITE SERIES. UPPER ESTUARINE SERIES. In the deep boring at the City Brewery, Oxford, beds of grey and black clay with iron-pyrites, " beef," lignite, &c., were encountered below the Great Oolite at a depth of 377 feet 8 inches, and proved to a thickness of 28 J feet. They were grouped by the late T. H. Blake (in conference with H. B. Woodward) with the Upper Estuarine Series. 1 "Jurassic Rocks of Britain," iv., p. 154. See also Proc. deal. Assoc., iv., ., p. 304 ; Hull, " Geol. Woodstock," p. 15 ; Walford, oc. t xli., p. 39 ; F. A. Bather, Ibid., xlii., p. 144. 2 Proc. Geol. Assoc., v., p. 384. See " Jurassic Rocks of Britain," iv., p. 151. p. 95; Hull, Geologist, iii., p Quart. Journ. Geol. 8oc. t xli., p 12 LOWER OOLITES. Particulars of these strata and of the fossils met with are given in the record of the boring (p. 124). Among the fossils were Cyrena?, Placunopsis socialis? M. & L. 3 Ostrea Sowerbyi M. & L., Mytilus sp., Hinnites sp., and Rhynchonella suhtetrahedra Dav. No outcrop of these strata has been observed in the region of the Oxford map, although they probably occur at the base of the Great Oolite in the north-western portion of the area. They are the clays previously referred to as overlying the Chipping Norton Limestone ; and they have since been proved to occur beneath the Stonesfleld Slate at Stonesfield by Mr. E. A. Walford, where, curiously enough, the thickness was exactly the same as that in the Oxford well, 28 \ feet. 1 From the occurrence in the clays of Necera, Mr. Walford designates them as the " Neseran Beds." GREAT OOLITE, FOREST MARBLE, AND CORXBRASH. The Great Oolite, together with the Forest Marble and Corn- brash, form the bluffs of the Evenlode between Hanborough Railway Station and Ashford Mill, and pass westward by a cross valley near Wilcote, to the Windrush. This will be referred to as the Wilcote Valley. A small area of the Corn- brash in a tributary valley of the Windrush near Witney is also included in the map. East of Hanborough the series extends by Bladon to Kidlington, where it passes northward outside our region. At Islip is a large inlier within the Oxford Clay area which shows all three divisions of the group. A smaller inlier on the north bank of the River Ray by Oddington extends to Charlton beyond the margin of the map. The divisions now to be considered are as follows : Cornbrash Zone of Macrocephalites macrocephalus, Szhlotli, Feet, tough shelly limestone in layers, without false-bedding or oolitic structure 9 to 17 Forest Marble Flaggy and shelly oolitic limestones, current- bedded and alternating with thick beds of clay and layers of gritty limestone ... ... ... ... ... ... 15 to 35 Great Oolite (Upper) White limestones with marls, evenly bedded, and with scattered oolitic grains Up to 60 Great Oolite (Lower) False-bedded oolitic freestone, shelly limestones, clays and sandy flags (Stonesfield Slate) ... Up to 40 Considerable difficulty is found in many places, as Mr. Woodward points out, in making any but conventional divi- sions between the Lower and Upper Great Oolite, and between the Great Oolite and Forest garble. It seems best, therefore, not to separate our descriptions of these formations, nor of the Cornbrash, which is also exposed in many of the pits. Witney. Near Witney the thickness of the Forest Marble, about 34 feet, is more than twice as great as it is at Hanborough, and the formation consists of false-bedded limestones covered by a bed of clay, which is persistent for several miles. Occasional small exposures of the Cornbrash may be seen by following the brook north-eastwards from Newland. The rock here, as in many other places, covers a wide area, the overlying Oxford Clay having been denuded 1 Eep. Brit. Assoc. for 1895, p. 415 ; " On some New Oolitic Strata in North Oxfordshire," 4to, Buckingham 1906, p. 18. GREAT OOLITE SERIES. 13 without any considerable destruction of the resistent beds below, so that the dip of the strata coincides almost exactly with the surface- slope. Wilcote Valley. In the Wilcote Valley the dip of the beds is slightly east of south, so that the outcrop of Forest Marble is much broader on the northern slope than on the southern. The relation of the white limestone of the Great Oolite with overlying Forest Marble may be seen in an old quarry a quarter of a mile west of Wilcote. Another section at the southern end of Holly Grove Plantation, Wilcote, showed only the hard, shelly, false-bedded oolite with clay-partings, be- longing to the Forest Marble. Near North Leigh and New Yatt the Cornbrash has been mostly concealed by the wash from the drift-beds at the top of the hill, and perhaps partially dissolved away at its outcrop by weathering. East of Bridewell Farm the white limestone of the Great Oolite was formely quarried for lime-burning. A section may also be seen south-east of Fisher's Gate, a quarter of a mile north-east of North Leigh Church : Ft. in. f Soil and rubble 3 6 Great Oolite -I Thin-bedded white limestone 5 (Clay 6 The limestone, which was said to be in thicker beds below, has been quarried for building-purposes, but is now only used for lime-burning. From this quarry the following fossils were obtained : Cijprina ?, Tri- gonia, sp. ; Nerincea, sp. ; M.esodon, sp. 1 An interesting section should be examined near Holly Court Farm, high up on the right bank of the brook. The flaggy oolites of the Forest Marble are there seen resting on the white limestone of the Great Oolite. Between the two is a thin bed containing fragments of the underlying limestone, and affording evidence of local erosion. Evenlade Valley. Below Ashford Mill practically the whole of the Great Oolite group is included in a bluff on the right bank of the Iliver Evenlode. The thickness may be estimated at about 130 feet. The Lower Division is not exposed, but a quarry showing part of the Upper Division, and the Forest Marble, may be seen a quarter of a mile south-east of the Mill, by the road-side. The succession of beds is given by Mr. H. B. Woodward as follows : Section in a quarry by Whitehill Wood, north of North Leigh (the uppermost beds were not accessible) : Ft. in. Forest Marble \ D^k ^ ' Greenish and white rubbly marl. Pale earthy limestone. Grey marly clay 4 Hard pale earthy limestone 1 3 Sandy marl, with bands of earthy and shelly limestone 5 Great Oolite j Oolitic limestone ,. 2 (Upper Division) ^ Blue and brown clay 4 Hard brown oolitic and shelly stone ... 3 Oolite 3 Greenish marl 2 Hard brown oolitic stone 1 White and pinkish shelly and oolitic lime- stones 8 1 These were named in the Palreontological Department. 14 LOWER OOLITES, This section includes higher beds than those at Ashford Bridge, and they evidently belong to the series of white limestones and marly beds above the freestone of Taynton : such as may be seen at Milton, near Shipton- under-Wychwood, some miles west of the area. The mass of the Great Oolite between Milton and Woodstock appears to be of variable character, and the Lower Division is probably much attenuated. 1 H. B. \V. On the left bank of the Evenlode there is a quarry showing the junction of the Lower Division of the Great Oolite with the Upper Division. This quarry is close to West-field Farm on the eastern side of the river, north of the railway and north-east of the Roman Villa of East End. The section shows false-bedded shelly white oolite with a thin band of marl in the upper part. The following fossils were obtained 2 : From the strata above the marl band. Astarte ? Trapezium sp. Nerinsea ? From the marl band. Acrosalenia cf. Wiltoni Wright Lucina rotundata ? (F. A. Roemer). Clypeus sp. Pholadomya heraulti ? Ag. Echinobrissus cf. Woodwardi Pleuromya ? (Wright). Tancredia ? Terebratula maxillata J. de C. Sow. Trapezium nuculiformis ? Astarte ? (F. A. Roemer). Cyprina cf. nuciformis Lye. Chemnitzia? Homomya ? Natica sp. Lima (Limatula) gibbosa ? (J. Sow.). Trochus ? From the strata below the marl band. Echinodermal remains. Pecten sp. Terebratula sp. Pinna cf. cuneata Phill. Lima sp. Pleuromya calceiformis (Phill.). Ostrea (fragment). Trigonia ? The Great Western Railway (Worcester branch) is carried along the valley by means of deep cuttings through the projecting spurs between the bends of the Evenlode. These cuttings, though much concealed, still show good sections of the Upper Division of the Great Oolite. Mr. Woodward remarks that the beds seen in the cutting near Ashford Bridge, north of the Mill, and just beyond the limits of the map, were as follows : Ft. in. Rubble of oolite, marl, &c. Fissile and false-bedded oolites and*) marls > 15 Oolitic limestone, with corals ... j Marly and carbonaceous oolite ... ~) Great Oolite. Clay and sandy shales, with Ostrea r 5 Sowerbyi 3 Pale-grey limestone with Nerincea Eudesi, Astarte angulata, &c. ... ... ... 1 Fissile and shelly oolite, with Nerincea at top 6 to 8 The section has been described by John Phillips and others 3 ; as well as by R. F. Tomes 4 who obtained from the Coral-bed, Astrococnia Phillipsi, Cryptoccenia Pratti, Isastrcea gibbosa, I. limitata, Montlivaltia, Tliamnas- trcea Lyelli, &c. He also obtained Cijathophora Bourgueti from the bed above the JVerincea-Umestone. A number of Gasteropods and other fossils 1 "Memoir on Jurassic Rocks of Britain," iv., p. 318 ; see also Green, Geol. Banbury, p. 23. 2 The specimens obtained during the recent Survey, have been named in the Palseontological Department. 3 Phillips, Quart. Journ. Geol. Soc.. xvi., p. 116 ; A. Gaudry, Bull. Soc. Geol. France, ser. 2, tomex., p. 594 ; J. F. Whiteaves, Rep. Brit. Assoc. for 1860, p. 105. 4 Tomes, Quart. Journ. Geol. Soc., xxxix., p. 171. GREAT OOLITE SERIES. 15 were obtained, by T. J. Slatter, from the Great Oolite in this cutting : they include Fibula variata, F. eulimoides, Natica Michelini, Neridomus minutus, Ataplirus discoideus, Delphinulaalta, and Solarium varicosum. Many other fossils, together with Cypricardia nuculiformis, and C. rostrata, have been recorded by Dr. J. F. Whiteaves. The lowest bed of oolite may perhaps represent the Taynton freestone, for as remarked by Tomes, all the beds "overlie the Stonesfield Slate, which is under the line of railway." H.B.W. The Stonesfield Slate does not appear in the area, but full particulars of the strata, the method of working, and lists of fossils have been elsewhere given. 1 At East End, north-east of North Leigh, are several quarries near together, which show the white limestone of the Great Oolite, the Forest Marble and the Cornbrash. It may be noticed that the Cornbrash, though so thin, here spreads out into a plateau half a mile long, similar to the broad outcrop of the same formation near Witney. At Combe Cliff, north of the railway and of Mill Wood, Long Hanborough, the strata are of the same character. The lower division of the Great Oolite is for the most part below the level of the river, but a considerable portion of the higher strata, comprising about 70 ft., is visible in the railway-cutting north-west of Mill Wood, and in the following quarry sections : Quarry east of Grintleyhill Bridge, about mile N.W. of Mill Wood. Ft. ( Thin-bedded shelly oolite 8 | Pale marl 1 Great Oolite -I Thick white oolitic limestone 2 I Marly limestone ... ... ... ... 3 I Thick-bedded shelly limestone ... 3 A quarry in the wood above Combe Cliff near the east side, north of the road, showed : Ft. Cornbrash 3 Fnr^tATrhl /Marl 14 e \ False-bedded limestone with clay beds ... 10 Along Combe Cliff, on the south side of the road, the white limestone of the Great Oolite is exposed. On the opposite side of the river the several divisions are again exposed in two quarries by the road leading northwards from Long Hanborough towards East End, Combe. The dis- used quarry south-west of the bridge over the Evenlode, is in the white limestone of the Great Oolite ; that known as Hanborough Quarry, north of the Swan Inn, showed the following section : Ft. Oolitic gravel 2 to 3 Cornbrash 9 T?~- ^ TV/I ! i f Greenish-grey clay 4 Forest Marble | False . bed ded limestone 4 Here may be noticed a considerable reduction in the thickness of the Forest Marble limestones. According to the information of the proprietor they disappear altogether in the field on the opposite side of the road. From this quarry, in 1904, we obtained two Ammonites, presumably from the Cornbrash, but not in situ. They were seen by Professor J. F. Blake, who named them Clydoniceras hochstetteri (Oppel), and Perisphinctes subbakerice (d'Orb-.). 1 H. B. Woodward, "Lower Oolitic Rocks of England," vol. iv.of " Jurassic Rocks of Britain,'' 1894, pp. 310-317 484,485. 16 LOWER OOLITES. The following fossils were obtained from the Forest Marble 1 : Pentacrinus (columnals). Cidaris sp. Echinoid remains (spines plate fragments). Serpula sp. Diastopora diluviana ? Edw. Microthyris obovata ? (J. Sow.). Rhynchonella cf. concinna (J. Sow.). ^bsoleta ? (J. Sow.). Terebratula intermedia? J.Sow. Ostrea Sowerbyi ? M. & L. and subrugulosa ? M. & L. Pecten (Camptonectes) lens J. Sow. -cf. personatus Goldf. Placunopsis socialis M. & L. Dentalium sp. Monodonta cf. tegulata Lye. Fish-remains. The change noticed in the Forest Marble at Long Han- borough quarry is still more marked in the railway-cutting by the station. The Cornbrash can be seen at the top all the way, coming to the level of the rails at the end nearest Oxford. At the opposite end the Forest Marble division consists of about 14 feet of clay with a thin stone-band in its upper part, and, underneath, the white limestone of the Great Oolite can be followed for about 500 yards towards the road-bridge, where it dips below the rails. The base of the Forest Marble is marked by a detrital bed containing fragments of the white limestone, as was observed near North Leigh. But near the bridge thick beds of oolitic limestone come in seven feet below the Cornbrash. They are at a higher horizon than the white limestone further west, and seem to belong to the Forest Marble. In appearance, however, they are more like some beds of Great Oolite. Very similar beds are seen in the quarry at the corner of the roads north- east of Hanborough Station ; they are as follows : Ft. Cornbrash Forest ("Rubble \Hardshellylimestone ( Grey clay with " race " I Compact brown limestone ... -^ | False-bedded and fissile oolite, I \ with thin partings of clay, and ! layers of hard shelly and blue- j hearted limestone in places, i Fish-remains (palatal teeth) J 12 The grouping here adopted differs from that given by Mr. Woodward who remarked that the lower beds appear to correspond with those referred to the Great Oolite in the quarry north-east of Bladon 2 . They are, how- ever, just like the strata that occur above the white limestone of the Great Oolite in the railway-cutting to the north-west. The following fossils were obtained : From the Cornbrash. Terebratula intermedia J. Sow. Lima sp. Microthyris obovata ? (J. Sow.). Pleuromya sp. From the strata below. Clypeus. Astarte ? Serpula intestinalis Fhill. Modiola sp. Diastopora ? Ostrea sp. Rhynchonella concinna ? (J. Sow.). Placunopsis socialis M. & L. 1 These have been named in the Pala?ontological Department of the Geological Survey. 2 " Jurassic Rocks of Britain," iv., p. 319. GREAT OOLITE SERIES. 17 Similar beds of Cornbrash and false-bedded limestone may be seen in an old quarry on the opposite side of the river near the bridge. The false-bedded limestones shown in these sections can be followed southward in a series of quarries near the road as far as the Mill, where the Corn- brash comes down to the river-bank and can be seen under the gravel terrace. By Pinsley Wood a slight upfold appears to bring the Forest Marble again to the surface, though it is not exposed in section. The Cornbrash, however, is seen in old quarries at the southern corner of the wood, and at Goose Eye Cottages by the river side. In a deep brook-bed west of Church Hanborough, Cornbrash is exposed for a distance of half a mile between banks of Oxford Clay. Below Hanborough. the steep bluffs which are characteristic of the river-course through the Lower Oolite rocks, gradually disappear, and the valley broadens out on the plain of the Oxford Clay. The white limestone extends to the mouth, of the Glyme by Bladon. Two miles to the south the top beds of the Great Oolite Series are finally lost at the foot of the slope by Purwell Farm. Glyme Valley. The following notes are by Mr. H. B. Woodward 1 : A quarry north-east of Bladon showed the following section : Ft. in. Soil Brown brashy loam 2 fHard brown and grey rubbly lime- Cornbrash < stones, with Terebratula intermedia C Sow 4 Blue and brown clay, with thin bands of shelly and oolitic limestone ... 3 6 False-bedded brown oolitic limestones with Rhynchonella 2 Blue clay (of irregular thickness), with lignite and compressed shells ... 8 Blue and grey marly oolitic limestone (of irregular thickness) 10 Dark blue and grey clay 1 6 Buff and blue false-bedded oolite. Bottom beds used for building ... 36 I Thin clay (impersistent). fBuff and blue oolitic and shelly lime- Great Oolite < stones without clay-partings. (Build- (. ing-stone.) Fish-remains ... about 10 [" Soft limestone, not worked."] The above grouping corresponds with that adopted by Professor Hull. 2 Although just beyond the confines of the map, the succession recorded in the railway-cuttings oil the branch railway to Woodstock will be useful for comparison : Ft. in. ( Fine yellow and grey sands 5 I Dark bluish-grey, and stiff mottled Kellawavs brown cla ^' with " race " and Roia -I much ferruginous matter at the base 10 I Thin layer of sand overlying seam of clay 5 1 " Jurassic Rocks of Britain," iv., 1894, pp. 373, 446448. 2 Geol. Woodstock, p. 23 ; see also Green, Geol. Banbury, p, 25. 9813 ,1 Forest Marble 18 LOWER OOLITES. Ft. in. f Rubbly and fissile marly limestone, with lignite : Waldheimia lagenalis (Schloth.), large O.streo 1 Impure limestones with lignite and pyrites : Rhynchonella varians (Schloth.) 1 2 Hard mottled limestones : Modiola, Pecten' lens Sow., Trigonia, Wald- heimia lagenalis, W. ornithocephala (Sow.) 1 6 Soft earthy and shelly marl and mottled blue and grey limestone : Astarte elegans Sow., Avicula Cornbrash { echinata Sow., Isocardia, Homomya Vezelayi (Laj.), Pleuromya, Ostrea, Pecten vagans Sow., Pholadomya Phillipsi Mor., Trigonia, Micro- thyris obovata (Sow.), &c. Hard bluish-grey limestones with marly patches : Avicula echinata, Gresslya, Pleuromya, Pecten vagans, Trigonia, Echinobrissus clunicularis (Lhwyd) Fissile marly beds and tough brown and grey shelly limestone, with Avicula echinata, and Terebratula intermedia (very abundant) fBlue and greenish-grey clay with J nodules of limestone... Shelly oolitic and marly limestone, false-bedded .. ... 1 ft. to , Blue and grey shaly clay and marly oolitic beds, with irregular layers of blue flaggy and false-bedded oolitic limestone f Oolites, presenting a somewhat mott- led appearance (like some beds of Cornbrash), with pale-grey, blue, and greenish tinges, due to irregu- lar staining and weathering : Nerincea (abundant), Ostrea and Corals 1ft. 6 in. to 2 Limestone 1 f t. to 1 6 Shelly limestone, with Astarte, Ger- villia, and some Gasteropods ... 1 Pale grey earthy limestone (blue- ^j hearted) I . ~ Compact limestones with scattered j grains of oolite J \ G reen and grey racy clay, passing down i into black carbonaceous and racy clay with much lignite 3 ft. 6 in. to 6 Earthy oolitic limestone, with Cy- prina, Ostrea Sowerbyi ; and gritty oolitic clay 5 Clay, Ostrea abundant 1 Slightly oolitic limestone, compact and shelly 1 ft. 8 in. to 2 Oolitic limestones 4ft. to 4 Fossil bed : marly limestone, occasion- ally oolitic, with Terebratula maxil- lata very abundant (all sizes and conditions), Lima cardiiformis, &c. 3ft. to 4 4 2 2 6 2 6 11 Great Oolite (Upper Division) GEE AT OOLITE SERIES. 19 The fossil-bed at the base merges irregularly into the bed above. The green and black clay recalls beds of Great Oolite Clay in the country to the north-east. It is difficult to correlate the strata with those of the Bladon Quarry ; indeed the limestones of the Great Oolite vary much in character, and there appear to be evidences of overlap and reconstruction at the base of the Forest Marble, suggesting local unconformity. (See also pp. 13,16.) The thickness of the Cornbrash was from 12 to 14 ft. Its basement-bed, crowded with fine specimens of Terebratula intermedia, was a noticeable feature ; and it was interesting to compare these forms with the allied and even more abundant specimens of T. maxillata found in the Great Oolite below. The limestones of the Cornbrash, as seen in this railway- cutting, were variable in character and induration ; where under the Kellaways Clay the rock was usually a hard dark blue or bluish-grey stone, much of it having a mottled appearance, not unlike some beds of Great Oolite. The mottled layers are caused by irregular admixture of marly matter. 1 H. B. W. The white limestones of the Great Oolite were well exposed in the old quarry at Hensington, by Bladon. In Blenheim Park the boundaries drawn between Forest Marble and Great Oolite, north of the Glyme, are conjectural owing to lack of evidence. A section north of the new bridge below the lake showed the following beds : Ft. Forest Marble ... Flaggy limestone 3 C White marl 3 Great Oolite I Hard white oolitic limestone 2 (. Fine-grained oolite On the drive between the High Lodge and Lince Lodge there are occa- sional openings in the Forest Marble ; one near High Lodge showed the Cornbrash as well ; and another, a quarter of a mile N.W. of Lince Lodge, showed the underlying White Limestone. These sections exhibit the flaggy and highly oolitic limestones characteristic of the Forest Marble, and their general persistence in this region, though they appear to thin away locally at Long Hauborough. Cherwett Valley. To the east of Bladon the Cornbrash spreads in a broad slightly inclined plane to the Cherwell. The Forest Marble crops out along the brooks north of Begbroke, and again west of Kidlington, but no lower beds come to the surface. These strata dip under the Oxford Clay between the two villages, and are not seen again towards the south. At Campsfield Farm, one-third of a mile north-west of Kidlington Station, the following quarry section was to be seen : Ft. Cornbrash 9 Forest Marble False-bedded limestone with thin clays... 20 In the adjacent railway-cutting the same two divisions have been exposed, the Cornbrash extending from the top at the north end down- wards towards the station, where it is concealed by river gravel. 1 "Memoir on the Jurassic Rocks of Britain,' iv., pp. 321, 373 and 447. c2 20 LOWER OOLITES. Half a mile due east of the railway-cutting, in an old quarry, Mr. H. B. Woodward recorded the following section, which is now partially concealed by slipping 1 : Ft. in. (Rubbly limestone, with Avicula echinata (abundant) 4 Grey racy clay 8 Cornbrash <( Rubbly limestone : with fine examples of IMicrothyris obovata in upper portion, and Terebratula intermedia in lower I part 3 f Blue-hearted gritty limestone 6 PY>t Mar.hi J Laminated calcareous sands and clays ... 1 ] Fissile shelly and oolitic limestone :' false- [ bedded. Seen to depth of 3 A large collection of Cornbrash fossils, including about 76 species, was made in this neighbourhood by Dr. J. F. Whiteaves. 2 The Ammonite Clydoniceras discus (J. Sow.), has been recorded from Kidlington. 8 Within a short distance of the sections above described the Lower Oolitic rocks disappear under the flood-plain of the Cherwell. Ray Valley. Along the northern margin of Ot Moor there is a remark- able series of inliers of the Great Oolite Series that protrude in isolated ridges surrounded by low alluvial tracts, over which wander the almost stagnant waters of the Ray and its tributaries. These inliers are situated along a line of upheaval, approxi- mately parallel to the general strike of the formations of the region taken as a whole. But there are minor disturbances in a direction at right angles to this, which cause undulations in the strata of smaller amplitude and wave-length. The structure is further complicated by faults, which in one case have displaced all the strata up to the Shotover Sands along a line extending from Islip across the Thame Valley, 12 miles away. The line of upheaval extends north-eastward into Buckinghamshire far beyond the limits of the map. In the opposite direction it may be clearly traced in the structure of Wytharn Hill, though the disturbance is much less intense ; but further on it appears to die out, for no Lower Oolites are brought up within the main outcrop of the Oxford Clay towards the south-west until we reach the neighbourhood of Trowbridge in Wiltshire. The largest and most disturbed of the inliers is approxi- mately bell-shaped, the length from north-west to south-east being rather over two miles, and the breadth somewhat less. It supports the villages of Islip, Noke, and Woodeaton. The general structure is an anticlinal dome dislocated by faults, but the complication of detail is too great to be determined with exactitude by such field-evidence as was available. The 1 "Jurassic Rocks of Britain," iv., p. 448. 2 Rep. Brit. Asfoc. for 1860, p. 107. See also Hull, Geol. Woodstock, p. 25 ; and Phillips, Geol. Oxford, p. 238. 3 J. F. Blake, " Monograph of the Fauna of the Cornbrash," Pal. Soc. 1905, p. 54. GREAT OOLITE SERIES. railway-cutting, of which a diagram is here given (see Fig. 2), though much overgrown, shows all the strata involved in the anticline. FIG. 2. Section of Islip Railway-cutting. Bridge. F Bridge. Railway Station. 4. Oxford Clay. 2. Forest Marble. 3. Cornbrash. 1. Great Oolite. F. Faults. Length of section, 600 yards. On the west, south, and east sides of the inlior the Cornbrash is seen to dip normally towards the clay tract beyond. North of Islip, however, the beds appear to strike tow r ards the Oxford Clay, as if the inlier were bounded by a fault in that direction. At the summit of Noke Hill and at Islip the Forest Marble emerges in irregular outcrops, faulted for a considerable distance on the east side against Oxford Clay. The White Limestone of the Great Oolite crops out on the west slope of Noke Hill, where it appears to dip normally under the Forest Marble towards the Kiver Cherwell, but on the other side the junction is probably a fault, though there are no sections to prove this. The two divisions are shown in a quarry at the cross-roads on the top of the hill between Noke and Woodeaton. The strata are nearly horizontal : Ft. in. {gj^Sg Z " ' 6 ...White limestone. Forest Marble Great Oolite Between this quarry and Islip the Forest Marble was formerly worked for road-metal, but there is now only one pit open about 200 yards south of the bridge over the Ray. It showed the following strata : Ft. in. Soil and Cornbrash ..................... 2 6 r Blue clay ............... 1 iWhiteinarl ............... 1 Forest Marble \ Oolitic brash (" pendle ") ......... 1 | Marly limestone with corals, Ostrea, Lima, I and large Pecten. At Islip quarry, one-third of a mile S.W. of the railway- station, close to the cutting, is the following section described by Mr. H. B. Woodward: Cornbrash Forest Marble and Bradford Clay Great Oolite f Rubbly limestone with Waldheimia (now \ Microthyris) obouata, Homomya, &c. ... 5 Grey clay with thin bands of limestone (impersistent) 1 Fissile layers of brown sandy and false- bedded limestone, ripple-marked ; with clay-bands j Blue and grey laminated clay 1 I Hard grey marl with dark oolitic grains and many fossils (impersistent) 1. Grey marly clay f Blue and yellow oolitic limestone, much \ false-bedded 5 Ft. in. 22 LOWER OOLITES. The fossil-bed yielded much lignite, also Lima cardiiformis, Ostrea Sowerbyi, Pecten lens, P. vagans, Waldheimia cardium, W. digona, Rhyn- chonella concinna, Serpula, Polyzoa, and spines of Echini. Numerous fossils were collected many years ago by Dr. J. F. Whiteaves from the Forest Marble at Islip and Kidlington. 1 Many of the specimens are now in the Oxford Museum ; they include, from Islip, Avicula costata, Corbula islipensis, Modiola irnbricata, Terebratula maxillata, Terebellaria rarnosissima, and Cidaris bradfordensis, forms indicative of the Bradford Clay, as suggested by Lycett. Another section north of Islip, showing about 5 ft. of Forest Marble, was noted by Mr. W. Whitaker, but is now covered. 2 Besides these there is a section of the flaggy false-bedded oolites in a quarry at the Home Farm, Woodeaton, and the Cornbrash is well exposed by a barn a quarter of a mile to the south-west. The marked dip of the strata to the south shows clearly the structure of the hill on this side. At the quarry east of Noke village the Cornbrash dips to the north-east. Between here and the Ray it is bent up into a subsidiary dome about half a mile in diameter, separated by a depression from Noke Hill, which probably marks the continuation of one of the faults in the Islip railway-cutting. On the other side of the river the villages of Oddington and Charlton stand on separate domes of Lower Oolite, each a mile long and a quarter of a mile broad, raised about 20 feet above the Alluvium of Ot Moor. The Cornbrash occupies the greater part of the surface, but the Forest Marble comes up in the middle, at the crests of the domes. They were shown in separate pits at Log Farm near the Ray. The white limestone does not crop out at Oddington, but it was seen by Prof. Green in a quarry, now disused, south-west of the Church. Ft in. ( Flaggy oolitic limestone, full of broken shells 1 Forest Marble ... -j Sandy clay and rubble 1 i Flaggy limestone (as above), with Ostrea I 3 l ~Pale blue clay 3 r- of n r . /White clay, mixed with limestone-rubble 1 "' ( Solid whitish limestone, very oolitic. The same author has given the following section at Charlton : FIG. 3. Diagram section through Charlton. (A. H. Green)? Windmill 2 Church Fault 1 Ft. in. 2. Cornbrash ... Rubbly limestone 2 f Flaggy oolitic limestone 6 1 Fnr^t MarblP I Yellowish marl 3 L * 1 Soft whitish oolitic limestones 3 ^ Pale blue clay 1 Rep. Brit. Assoc. for i860, p. 106 ; Green, Geology of Banbury, p. 29 ; Lycett, Supp. to Great Oolite Mollusca, p. 64 ; Phillips, Geol. Oxford, p. 153. 2 Green, op. cit., p. 35; Hull, Explan. of Hor. Sections, Sheets 71 and 72; Geol. Survey, p. 3. Geology of the country round Banbury, &c., 1864, p. 36. OXFORD CLAY. 23 CHAPTER III. MIDDLE OOLITIC EOCKS. BY H. B. WOODWARD AND T. I. POCOCK. OXFORD CLAY AND KELLAWAYS BEDS. This formation takes its name from the county of Oxford, where it enters extensively into the structure of the ground; moreover, it is exposed in the neighbourhood of the City of Oxford in several brickyards which appropriately furnish some of the larger inland sections of the formation. The Oxford Clay consists of bluish or greenish and lead- coloured clay, which usually becomes brown or yellowish-grey at the surface. In many places, and more especially in the upper part, the bedding fn the clay is not distinct, and is marked only by bands of septaria and occasional layers of earthy limestone; but lower down the formation is usually more shaly, and this character is maintained even when the beds come near the surface. The shale is grey and reddish- brown or purple in colour. Both clay and shale are often calcareous, and occasionally bituminous; and lignite is some- times met with. Septaria occur at irregular intervals and they may attain a large size, having a diameter of 3 feet or more. The beds contain much iron-pyrites and selenite; and many of the fossils are of a pyritic character. The hard sandstones near the base of the Oxford Clay, to which the name Kellaways rock was originally applied in Wiltshire, are represented in the neighbourhood of Oxford by sandy and loamy beds that have been exposed near Bicester, and on the branch railway to Woodstock, to the north of the area. (See p. 17.) Here, as in many other localities, there is from 10 to 12 feet of clay at the base of the Kellaways Beds. Doggers of calcareous sandstone often occur in the sands of this sub- division. The Oxford Clay, which is estimated to be nearly 400 feet thick in this region, occupies an area almost as great as that of all the other strata taken together. Rising in somewhat bold and rounded hills above the Great Oolite Series, the lowest zone of this formation spreads from the Windrush, near Witney, by Osney Hill and North Leigh to Hanborough on the Evenlode, and thence by Bladon Heath to the Cherwell, beyond which it passes northward outside our region. The upper zone forms the lower slope of the Corallian escarp- ment, which runs with broad curves from Hinton Waldrist to Cumnor, and round Wytham Hill to the Hinkseys, and from Iffley by Elsfield, Beckley and Studley, to the north of Muswell Hill. South-eastward of Ot Moor the outcrop is pro- 24 MIDDLE OOLITES. longed, by Hie removal of the overlying Corallian Beds, almost to the Thame at Waterperry. Through the middle of this broad tract flows the Kiver Thames as far as the gap in the Corallian formation below Iffley, and much of the surface of the clay is covered by sediments laid down by the river at former stages of its history. The Oxford Clay has been divided into the following Ammonite zones : f Clay with septaria and ironstone nodules. Cardioceras cordatum \ Clay with pyritic fossils (subzone of Quenstedto- C ceras Lamberti). Cosmoceras ornatum ] Shales *' ith Pyritic f Ssils < 3llbzone of Cosmoceras (_ Jason). f Cla ^ and shale with sand-beds and concretionary 1 masses near the base (Kellaways Rock). (Clay (Kellaways Clay). The lowest zone may be said generally to be that part which comes to the surface north-west of the Thames alluvium as far as Yarnton, and in the vicinity of the Lower Oolite inliers by Ot Moor. The middle zone is, to a large extent, covered by alluvial deposits, while the upper zone forms the sloping land leading up to the Corallian escarpments. The sands of the Kellaways Beds are seldom to be seen; they are marked by a belt of marshy ground with springs, which is usually found shortly after passing from the Corn- brash to the Oxford Clay area ; - and they are accountable for the somewhat sharp feature with which this formation rises above the rocks below, as in Burleigh Wood, south-west of Bladon, and to the east of Church Hanborough. From time to time these basement-beds have been opened in the railway-cut- ting at Islip Station, where they are faulted against an inlier of Lower Oolitic rocks. Numerous doggers have been found with Kepplerites calloviensis. Between Long Hanborough and North Leigh at " the Demesnes," where drift-gravel is obtained for road-metal, a few feet of the lowest zone of Oxford Clay are exposed. Two distinct types are to be seen. Below are dark purplish shales, while directly under the drift is a tough clay of paler greenish colour with mottled veins of red. No fossils were observed here, but in the foundations of the new hall in Eynsham Park, where similar beds were to be seen, some fragile Ammonites were obtained. The brick pits at the north-east corner of the Park and on the top of Combe Hill also show clay at nearly the same horizon. North of the city of Oxford deeper excavations have been made, of which the following particulars have been given by Mr. Woodward. On the Woodstock road near Summertown, there is a large pit, where, beneath eight or ten feet of valley- gravel, the Oxford Clay, consisting of bluish-grey or lead- coloured clay with occasional scattered septaria, has been dug to a depth of about 40 feet. Some of the septaria contain lignite. The clay is slightly calcareous, and many of the Ammonites are pyritized. Cardioceras cordatum occurs in the upper part, together with Gryplicea dilatata, and lower down we find Cosmoceras Duncani, Qitenstadtoceras Lamberti, 'B'elemnites hastatus, B. sulcatus, &c. ; likewise, Kepplerites OXFORD CLAY. 25 callovwnsis, Macrocephalites macrocephalus, Peltoceras William* soni, and Nucula ornata. Thus portions of the chief zones of the Oxford Clay are here represented. The occurrence of fossils belonging to the three main zones is confirmed by specimens in the Oxford Museum and in the collection of Mr. James Parker. These include, in addition to some of those mentioned above, Peltoceras athleta, (ETcotraustes crenatus, Cosmocwas gowerianum, Cosmocems Jason, Quenstedto- ceras Marice, &C. 1 No doubt the beds at Suinmertown should be grouped mainly as the zone of Cosmoceras ornatus regard- ing that as a general palaeontological horizon. Close by the railway-tunnel at Upper Wolvercot, there is another large pit showing 40 feet of Oxford clay, with gravel and loam on top, similar to the section at Summertown. The septaria are scattered, there being no conspicuous band of them. Among the fossils Gryphcea dilatata and Belemnites sulcatus are most abundant. K&pplerites calloviensis also occurs. Half a mile further on the Woodstock road 20 feet of clay has been dug at the brickyard on Peartree Hill. In St. Clement's, south-east of the city, owing to the prevalent dip of the strata in that direction, the higher zone of the Oxford Clay is exposed in the brick pits. From the pit near the workhouse on the Cowley road, Mr. H. B. Wood- ward obtained Cardioceras vertebrale, Belemnites eacentricus, B. Oweni, and Gryphcea dilatata.. Other species from this locality in the Oxford Museum and in the collection of Mr. James Parker, include Cardioceras cordatum, Quenstedtoceras Lamberti, Belemnites hastatus, B. sidcatus, Rhynchonella varians,.Pentacrinus Fisheri\ also AsteracantliMs and Hybodus, as well as Saurian and Crustacean remains, the latter com- prising Glyphea, Eryma, and Goniocheirus. The pit by the roadside, half-way between Magdalen Bridge and Marston, showed 20 to 30 feet of clay belonging to the Upper Zone. In the great tract of Oxford Clay south-east of Ot Moor there is only one section to record. This is the small brickyard by the roadside half a mile south-east of Studley. The clay belongs to the Upper Zone and yields Gardioceras vertebrate, and the characteristic Gryphcea dilatata. But though sections are few in number, the gryphaeas occur in such profusion that it is only necessary to walk over land directly below the Corallian escarpment to pick them up in abundance from the ploughed fields, ditches and ponds. 1 See Phillips, Geol. of Oxford, p. 304. 26 MIDDLE OOLITES. CHAPTER IV. MIDDLE OOLITIC ROCKS (continued). BY T. I. POCOCK, WITH NOTES BY H. B. WOODWARD. CORALLIAN. Between the Oxford Clay and the Kiineridge Clay there is a variable series of sands and rock-beds that are well shown in quarries near Abingdon, and in the neighbourhood of Oxford. They are again seen at Upware, near Cambridge; but over the chief part of the area between Wheatley, east of Oxford, and North Lincolnshire, this intermediate formation is repre- sented mainly by the Ampthill Clay. Buckland, in 1818, divided the rock-beds near Oxford into Calcareous Grit, Coral Rag, and Upper or Oxford Oolite. 1 Since then, our knowledge has been largely amplified by Fitton, John Phillips, and especially by Prof. J. F. Blake and Mr. W. H. Hudleston, who, in 1877, gave a very full description of the strata and their fossils. 2 Grouped now as Corallian, the rocks admit, near Oxford, of the following general divisions : Upper / Coral Kag and Coralline \ Zone of Perispkinctes Corallian \ Oolite (12 to 40 ft.) f plicatilis Lower J Calcareous Grit and 1 Zone of Aspidoceras Corallian \ Sands (20 to 60 ft.) j perarmatum At Marcham and Oxford the upper division comprises rubbly coral-limestones, with local sandy and clayey inter- calations; and with calcareous grit and sands beneath. In some places these are so intimately connected that we can fix no definite plane of separation ; elsewhere they are clearly marked off one from the other, and there are indications of local erosion. Near Wheatley beds of oolite and shelly limestone are intercalated in the Upper Corallian division. Among the fossils of the Calcareous Grit perhaps the most remarkable is the Ammonite Aspidoceras perarmatum, which occurs at Marcham and other localities, with the chambers only preserved in the form of casts. Specimens of this kind were named " Ammonites catena." 3 The interior of the Ammonite was filled with ferruginous and calcareous mud or sand, and ihe shell and septa have subsequently been dis- solved away, leaving only the casts of chambers in a loose form or linked together so as to resemble a rough tapering chain. Cardioceras cordatum also occurs in the form of casts. Among Corals, the " Honeycomb Coral," Isastrcea explanata, so abundant at Headington, also Thecosmilia annularis, and Thamnastrcea arachnoides, are those more commonly to be obtained. 1 Table appended to the Outline of the Geology of England and Wales, by William Phillips, 1818. 2 Quart. Journ. Geol. Soc., xxxiii. p. 389 ; Geol. Mag., 1878, p. 91. 3 See Sowerby, " Mineral Conchology," v., p. 21. CORALLIAN. 27 Dr. J. F. Whiteaves many years ago zealously collected the fossils from the Corallian rocks of Headiiigton, Bulling- don, Cumnor, Bessels Leigh, and Marcham, but he did not separate the species from the Lower Calcareous Grit and the Coral Rag, as the boundary between the divisions had " not been accurately defined." 1 Subsequent research shows that there is indeed no definite boundary, and that the divisions, though marked in some places, are for the most part arbitrary. H. B. W. Longworth and Kingston Bagpiiize. One of the best sections of the Corallian rocks was exposed in a quarry by the Lamb and Flag Inn, south of Longworlh, and about two miles west of Kingston Bagpuize 2 : Soil about Upper Corallian 12. Reddish-brown earth r ll. Marly bed | 10. Flaggy and gritty oolitic stone ... 9. Oolitic sandy debris, with dark clayey streaks, and occasional lydite pebbles : EcMnobrissus 8. Laminated clay and sand with irregular white calcareous seams 7. Oolitic limestone ; few fossils 6. Marly oolitic layer : Pleuromya 5, Hard pale grey shelly limestone. Trigo- nia-bed : Cardioceras cordatuw, Trichites, and casts of shells at base 4. Brown earthy rock with casts of shells, Pleuromya, &c. : passing down into blue rubbly pisolitic rock, and this merges into bed below 3. Grey shelly limestone, oolitic and piso- litic, with rolled fragments of hard limestone, bored by Lithodomi and encrusted with Serpuhe: small pebbles of lydite and quartz ... Calcareous / 2. Hard grey calcareous grit, impersistent Grit 1 1. Buff sands. Ft. 3 1 1 1 8 2 The main mass of shelly and oolitic limestones varies from about seven to twelve feet in thickness. Among the fossils from the beds 3 to 7, but chiefly from bed 5, are Perisphinetes plioatilis, Cardioceras cordatum, Belemnites aUbreviatus, Modiola cancellata, Trigonia perlata, T . Meriani, Trichites, Gerwllia avi&idoides, Alectryonia grogwria, Perna mytHoides, Hinnites tumidus, H. velatus, Pecten demissus, P. ftbrosus, P. lens, Lima pectiniformis, L. rigida, Echinobrissus scutatus, &c. Many of these and other species were recorded by Messrs. Blake and Hudleston. 3 They noted that the upper sandy and clayey beds (8 and 9) rested uncon- formably on the limestones below. There is also indication of a local break at the base of bed 3. 1 Ann. and Mag. Nat. Hint , ser. 3, riii., 1861, p. 142. ' H. B. Woodward, " Jurassic llocks of Britain/' v., pp. 122, 123. 3 Quart. Journ. Geol. Soc., xxxiii., p. 304. 28 MIDDLE OOLITES. Prof. Hull 1 here grouped the top strata of sand and clay as " Upper Calcareous Grit," but there appears no justifica- tion for tracing such a subdivision on the map. No Coral-beds were observed hero, but they may have been removed by contemporaneous erosion. The whole section is a good illustration of the rapid alternations of different sedi- ments that took place in the shallow waters of the Corallian period. Other sections may be seen near Pusey Lodge Farm, and three-quarters of a mile south of Lower Lodge Farm. Eastwards, along the plateau, by the road from Kingston Bagpuize to Fyfield, the Calcareous Grit is quarried in several places for building-stone. A brown sandy and loamy soil covers much of the area in this neighbourhood. Professor Hull figured a section a quarter of a mile east of Kingston Bagpuize, where the Lower Calcareous Grit is very obliquely bedded and pebbly. He estimated the total thickness of the Calcareous Grit at from 20 to 80 feet, and the Upper Corallian at about 10 feet. 2 FIG. 4. Quarry near Kingston Bagpuize., west of Alrincjdon. (Prof. E. Hull.) A. Upper Corallian (Coral Rag). Rubbly and shelly limestone, with casts of shells ; few Corals. B. Lower Corallian (Calcareous Grit). Irregular beds of calcareo- siliceous rock, conglomeratic ; fossils fragmentary ; alternating with coarse brown siliceous sand, with pebbles of quartz, lydian-stone, &c. Beds obliquely laminated. This is probably the quarry at the cross-roads south of Woodhouse Farm. Very similar beds were shown in a pit half a mile further on towards Abingdon. A mile east of Tubney, near the cross-roads, a good section showing the Calcareous Grit has recently been reopened after the quarry had been disused for many years. The beds are mostly yellow sand, but they are indurated in bands and irregular masses, which are much broken and iron- stained. At a depth of about 10 feet is an intensely hard blue gritstone with shale-galls, lignite, and casts of shells ; this rock was quarried for building-purposes. The sand is in part the decalcified remnant of cal- careous sandstone. Marcham and Appleton. The well-known quarries of Harcham show the most complete series of Corallian strata to be found in the district. In the pit by Sheepstead Farm is seen for the first time the Coral reef, which, from here till the formation dies away to the north-east of Shotover Hill, is a characteristic feature of the rock-plateau overlooking the Oxford plain. In the same quarry the TY^oma-limestone, which was seen at 1 Geol. Parts of Oxfordshire and Berkshire, p. 7. 2 Geol. Parts of Oxfordshire and Berkshire, p. 6 ; see also Explan. Hor. Sec., sheet 72, p. 7. CORALLIAN. 29 Kingston Bagpuize, and the Calcareous Grit are shown below the Coral-beds. The two former divisions only are found in the next quarry to the east, near Gosford, but a mile to the west of Marcham the complete sequence occurs again near the Noah's Ark Inn, though it is not so well seen as formerly. The general section at Marcham noted by Mr. Woodward is as follows 1 : (See Fig. 5.) Ft. in. 7. Red and brown earthy soil. 6. Impure, slightly oolitic limestone, passing down into rubbly coral-rock and clay 6 5. Oolitic and sandy marl, passing down into earthy oolitic limestone and rubbly oolite, with Trigonia-bed 4, at base. This fossil-bed tapers away towards the western part of the Sheepstead Farm quarry ... ... ... ... 2 6 3. Reddish brown and white shelly sands, with indurated fissile beds and lami- nated clay ; pebbly layer at base, Upper when resting directly on the Calcare- Corallian 1 ous Grit 2ft. Gin. to 4 2. Oolitic, flaggy and gritty limestone, 1 foot, tapering away eastwards in the Sheepstead Farm quarry, and replaced by rubbly oolite, and by a conglome- ratic band with pebbles of lydian stone, oolite and bored limestone. In the quarry to the north-west this fossil-bed is again seen, where it is 2 feet thick and conglomeratic. It contains Serpula, Trigonia and many Lamellibranchs ; also Natica marcha- mensis 1 ' 1 . Hard calcareous sandstone (1 ft.), Natica- ") bed (of Blake and Hudleston), with I N. marchamensis : in some places ! united to the fossil-bed above, in I other places separated by a thin bed of shelly sand (6 in.), with Exogyra nana, Gervillia, Pecten fibrosus, and Ostrea solitaria... ... ... ... ! I False-bedded buff and ochreous sands with Lower Corallian (Calcareous ] Grit) ironstone concretions, streaks of clay, } 8 pebbles of quartz, and lydian stone : ] Alectryoniagregaria, lignite, &c. Here and there the mass of the strata up to the base of the Upper Division con- sists of layers of fissile calcareous sandstone occasionally ripple-marked ; in other places there are only imper- sistent and irregular layers and dog- gers of sandstone In the Upper Corallian Beds the higher Trigonia-bed yields Peris- pliinctes plicatilis, Belemnites abbreviatus, Astarte ovata (Smith) 2 , Lima pectiniformis, Trigonia perlata, Alectryonia gregaria, Echinobrissus scutatus, Pygaster umbrella, Lignite, &c. The lower fossil-bed is also a Trigonia- bed. The presence of sandy beds among the fossiliferous Upper Corallian 1 "Jurassic Rocks of Britain," iv., p. 124. The pit at Sheepstead Farm was formerly known as the Oakley House quarry. 2 Preserved in the Museum of Practical Geology. 30 MIDDLE OOLITES. 1 s a * s o -2 1 * I 8-3 I rocks, and the occurrence of the two fossil-beds and their im per- sistent character, form interest- ing features. The sands of the Calcareous Grit at this locality have been famous for fine examples of Aspi- doceras perarmatnm (see p. 26). Casts of Cardioceras cordatum are also met with. Here, too, Hemipedina marchamensis occurs. The sections at Marcham, in- cluding a quarry at Noah's Ark further south, have been de- scribed by Messrs. Blake and Hudleston, who record many fossils. 1 They drew attention to the evidences of local erosion, but the lower fossil-bed was not exposed at the time of their visit. The irregular cementation of the sands of the Calcareous Grit into doggers and into bands of sandstone was well shown in the quarries near Marcham. H. B. W. Northwards from Abingdon, along the Cumnor road, small openings show the Coral beds with a variable thickness of weathered rock at the top. At Dry Sandford, to the west, the two Corallian divisions are again seen as follows : Ft. Coral Rag... Coral rock and rubble ... 3 C Buff sand with tufaceous rock containing uni- valve shells . 3 Calc. Grit- "Si ee'S AV These show that the Trigonia- limestone beds, very well deve- loped farther west, have com- pletely died away, so that the Coral-bed reposes directly on the sands and grits of the Lower Division. Sections of the Lower Division may be observed at Cothill and to the south-east of Appleton, where 12 feet of buff sand with shelly rock were exposed. Cumnor. Tothe south-east of Cumnor, ^ y> tt)+** and near Bradley Farm, as 1 Quart. Journ. Geol. Soc., xxxiii., pp. 305, &c. ; see also H. B. Woodward, Proc. Geol. Assoc., xii., p. 331. H3 A d d " = o ,31 11 8 * * .1 mm 1 -b 1 1 .2 (SS^^JO t [15 but few corals = " Coral beds"".*. J Shelly sand, with Natica corallina 2 "I Hard calcareous sandy bed... 10 in. to 1 I Sand 2 | Shelly calcareous grit (employed for I building railway bridges).... ...2ft. [to 2 fBuff sands with spherical and elongated concretionary masses of hard calcareous sandstone (blue hearted), 4 X 5 X 2 ft. and less in size, like the " doggers " in the Bencliff Grits of Weymouth : I occasional streaks of clay 15 Upper Cor.'illian Lower Corallian (Lower Calcareous Grit) in. 7] 6 6 6] 1 ft Mineral Conchology," i., p. 86. 36 MIDDLE OOLITES. Here, as at Bullingdon, we have a difficulty in making any separation between Upper and Lower Corallian Beds; there seems to be no evidence of any local break, and the sandy strata below the Coral-beds are doubtfully referred to the Upper Corallian, though they appear to represent the fossili- ferous beds of Fyfield and Marcham. The beds undulate very much in the railway-cutting west of Littlemore Station, but the general inclination is west- wards. In 1867 Mr. T. Codrington noted that there were numerous small faults in the cutting. " They show as faults in the rocky bands, but above, the clayey rubble-beds appear as if contorted this is due wholly to the faults." 1 The clayey Coral-beds make heavy land on the slopes to the west. The section at Littlemore was described by Mr. E. S. Cobbold, on whose authority we insert the thickness of the upper clayey and marly beds. He states that, in laying the sewage-pumping main along the road up Sandford Hill, there was a thickness of about 12 feet 6 inches of very hard fine- grained limestone above the marls; it occurred in three or four layers with hardly any fossils. Above this, again, there was a stratum of very sandy limestone, 2 feet 6 inches thick, suggesting a trace of "Upper Calcareous Grit." (See p. 28.) A trial-hole on the Sewage Farm about a mile east of Sandford, showed the following section 2 : Ft. in. Soil ........................ 2 6 [Upper Corallian] Brown earth ... ... ... ... ... 1 Black earth ............... 1 2 Marl, rubble ............... 1 Hard blue stone ......... ... 1 Marly clay ............... 9 Blue stone ............... 6 Marly clay ............... 5 The Corallian Oolite was not present, but in the opinion of Mr. Cobbold, " it had entirely changed its character in the short distance (one mile) from Sandford." He suggests that " the influx of clay may have been due to the muddy discharge from some river which might hinder or altogether check the growth of corals, while it was favourable to that of oysters," and that " the supposed river cannot have been very large or very far off." ... "It seems therefore probable that the Paleozoic rocks known to exist beneath London may have been above water in the later Oolite period, and have had considerable extension to the S.W. and E."- In the several sections from Littlemore onwards we have indications of similar changes to those which the Corallian strata undergo to the north-east of Wheatley, and which presumably take place also to the south-east of that locality, and of Sandford. H. B. W. 1 MS. note communicated to Mr. Whitaker. 2 No. 3, Fig. 7, in paper by E. S. Cobbold, Quart. Jown. Geol. Soc., xxxvi., p. 319. See also Prestwich, Hid., p. 431 ; H. B. Woodward, ibid., xlii., p. 307. CORALLIAN. 37 Elsfield and BecTdey. North of Headington the Corallian escarpment is deeply indented by a stream rising at Forest Hill, near Wheatley, which, with its tributaries gathered from the rock-beds, forms a considerable extent of marsh-land at the foot of the slopes. Near Wick Farm the Calcareous Grit has a narrow outcrop, and is evidently much thinner than on the opposite side of the valley at Headington. At a small pit one-third of a mile N.N.W. of the farm, the Coral Kag is seen to consist of limestone-beds full of corals and crinoid stems, with also Exoyyra and other fossils. In Wick Copse, hard by, the thickness of the lower division can scarcely exceed 20 feet; but near Elsfield it increases again. Indeed, so much of the formation appears to consist of sand, that no satisfactory boundary-line could be drawn between the two divisions. At a pit a quarter of a mile from Stow Wood, on the road to Elsfield, 5 ft. of Coral-limestone, overlying a similar thickness of shelly limestone, was seen. This quarry is close to the line of disturbance which was mentioned in the account of the Lower Oolites of Islip (p. 20). The faulting appears to be complicated, but owing to the meagre field-evidence it could not be deciphered in detail. The general effect in this region has been to throw down all the beds some 50 ft. on the south-west side of the disturbed area, as may be seen if the escarpment is viewed from the top of Noke Hill, near Islip. The crest is observed to be much higher on the left side of the road to Wheatley than on the right ; this road being coincident with the fault where it reaches the brow of the hill. If the ground be examined more closely it will be seen that from the corner of Stow Wood, south-eastwards for about a mile, the rising ground on the one side consists of sands belonging to the Calcareous Grit, while at a lower level on the other side is the Coral Rag. Beyond this the evidence is not so clear, though the fault is very conspicuous in the vicinity of Forest Hill. The rolling character of the surface in the disturbed area contrasts with the prevailing flatness of the Corallian plateau at Headington. Between Stow Wood and Woodeaton the Upper Corallian is thrown down almost to the bottom of the hill in a trough between the main fault and one close by on the south-west side, the displacement being probably nearly 2 )0 ft. on one side, and upwards of 80 ft. on the other. At Druns Hill is a small outlier in which the beds have a well-marked inclination to the south, and are cut off abruptly in that direction against the Oxford Clay in the bottom of Woodeaton Wood. A disused quarry at the top of Druns Hill showed 6 ft. of well-bedded shelly limestone, with partings of marl full of specimens of Exogyra. North-east of the faulted belt there is again much difficulty in drawing a line between the two Corallian divisions, on account of the sandy character of the whole series. A thickness of 40 or 50 feet of Calcareous Grit is shown near Beckley, but there is not more than 30 feet at Woodperry and Stanton St. John. In the road-section, now overgrown, at Woodperry, south-east of Beckley, Prof. A. H. Green observed a hard lime-cemented sandstone at the base of the formation, with a thin band of clay in the middle ; the coral limestone at the base of the upper division is seen for the last time in a small quarry close to Woodperry House. At the top of the hill, half a mile along the road to Oxford, there is another quarry, in which higher beds of limestone are seen: they contain no coral growths, but are full of sea-urchins. 38 MIDDLE OOLITES. The strata were noted by Mr. Woodward as comprising hard crystalline oolitic limestone used for road-metal and rough walling ; with also beds of " freestone," a softer rock, which hardens on exposure, and is used for building purposes. Perisphinctes plicatilis occurs here. Stanton St. John, Wh&atley, and Oakley. BY II. B. WOODWARD. Near Stanton St. John, rag-beds have been quarried, and there Messrs. Blake and Hudleston noticed the abundance of Echinoderms, Cidaris florigemma, EcMnobrissus scutatus, and P seud&diaderrta versipora\ while Corals seem to be absent or very scarce. 1 The section at the quarry, now disused, at the south- eastern end of the village of Stanton St. John, was given by Prof. A. H. Green as follows : Ft. ( Rubbly limestone, full of broken fossils 3 Yellow and brown sandy clay, with irregular beds of concretionary limestone, full of broken shells, Ostrea sandalina (= Exogyra liana), &c 10 LHard, dark-blue limestone ... ... ... 6 The sands of the Calcareous Grit have been largely worked between Elsfield and Beckley. 2 At Stanton St. John, near the school, there is an old quarry in which there are exposed about 10 ft. of rubbly limestone and marly clay, over- lying hard sandy limestone, 1 ft. to 1 ft. 4 in., and brown sands and sandy limestone, exposed to depth of 4 ft. There is here a gentle dip to the S.W. North of the George Inn there is an old limestone pit, probably in the lower part of the Upper Corallian and in subjacent sandy series. Gryphcea dilatata was here met with. Cherty sandstone occurs by the woodside east of Stanton St. John, not far from the junction of the Lower Calcareous Grit with the Oxford Clay. At Shepherd's Quarry, south-west of Stanton St. John, where the strata have also a general south-westerly dip, the following section was noted: Ft. Grey soil ... ... ... ... ... ... ... ... 1 Reddish-brown brashy subsoil I ft. to 3 Grey clay ... ... ... ... ... ... ... ... 1 Hard grey limestones, with bands of rubbly limestone and marl : spines of Cidaris florigemma, Serpula, Belemnites, Exogyra nana 12 ft. to 15 A good deal of " rock milk " coats the faces of the jointed limestones. Building blocks are obtained from the harder bands of grey limestone. On the north-western side of Wheatley there are large quarries, where Corallian limestone is worked for building- blocks and lime-burning. The rock here forms part of the faulted belt that extends from Woodeaton to the south- 1 Quart. Journ. Geol. Soc., xxxiii. , p. 310. ? Green, Geol. Banbury, &c., pp. 43, 44. CORALLIAN. 39 eastern base of Red Hill, through Wheatley Village, beyond which there is no further exposure of Corallian limestone. Near to Red Hill are the Lyehill Quarries, where about 50 feet of Corallian limestone occurs in massive beds. Harder layers of shelly oolitic and pisolitic limestone are inter- bedded with softer layers, and near the surface these are disintegrated into crumbly beds of shell-sand from which fossils may readily be extracted. These are few in kind, but include Cidaris florigemma (spines), Ettogyra nana, and Ostrea. The strata are inclined to the N.NJB., but it is not clear whether this apparent dip is the result of false-bedding, or only slightly so. In the quarries at Wheatley Tillage the stone is worked to a depth of 30 or 40 feet. The mass comprises oolitic shell- limestone, in harder and softer bands. The harder bands are the more shelly, and they are blue-hearted; the softer bands are more oolitic. The shelly stone is burnt for lime, and the oolitic freestone (which hardens on exposure) is used for building-purposes. The upper layers are fissile, and there is much decomposed shelly sand and oolite, with about 2 feet of brown brashy soil. The fossils at Wheatley include Cidaris florigewma (spines), Serpida, Exogyra nana, Chemnitzia^ Belwnnites alybrewatus, and Peris phinctes plicatilis? (J. Sow.); the last-named was found in the upper portion of the section, below the fissile bands. Exoayra nana is abundant throughout the beds* In the Oxford Museum there are remains of a Saurian jaw from this locality. The quarry by the old " lock-up " at Wheatley is utilized in part for the reception of town " rubbish," an unfortunate and ill-advised proceeding, considering that much water for the supply of houses is obtained from this mass of limestone. Rubbish has also been shot into a disused quarry in the meadow further west, in proximity to a well. In this old pit the Lower Corallian was probably reached. It is difficult to decide whether the old pits in the meadow between Wheatley Station and the town were wholly in Corallian rock or partly io Kimeridge Clay. No positive evidence was to be gathered, either from the pits or by enquiry in the village. Nor could any information be obtained respecting the pits in Shotover Park. That by the Steward's house is now a shrubbery, and dry it was probably opened for stone. The pits further south show only clay, but may have been excavated through the Kimeridge Clay into the Corallian stone. The general strike of the Corallian strata is from the north- west towards Wheatley railway-station, where the beds are faulted against the Kimeridge Clay, which lies to the south-west. This fault extends to the north of the railway towards Wheat- ley Bridge. The Corallian is likewise faulted along its eastern and north-eastern borders, between Wheatley and Holton, so that the limestones are preserved by a kind of step- faulting. The throw of the main faults is, however, modified by transverse faulting, as at Forest Hill, where the Portland and Shotover Beds are let down between Kimeridge Clay and Corallian by normal trough faulting. Moreover, the general line of fracture and displacement is continued in a south- 40 MIDDLE OOLITES. easterly direction through Great Milton, where an inlying tract of Kimeridge Clay gives indication of disturbance. The relations between the Kimeridge Clay of Waterstock, south of the Thame, with the clayey Corallian Beds on the north, were nowhere displayed. It seems evident that the Wheatley rock passes into thin sands and clays with Exogyra, and that the equivalents of this and of the lower division, with its occasional rock-bands, are not to be separated in the area to the north-east. Messrs. Blake and Hudleston remark : " We are here, then, presented with the deposits which were formed on the extreme edge, not only of the coral reef, whose thickness would not account for so much false dip (which amounts in the most easterly quarry to 12, and is even marked at 18 at another spot on the [Geological Survey] map), but probably of the Lower Calcareous Grit sandbank also a conclusion which is supported by the fact of its apparent sudden termination east- wards." They add that " the Corallian formation has died out, not gradually, but suddenly, and the normal pelolithic formation reigns supreme." 1 Since this Memoir was written Mr. A. Morley Davies has published the results of researches which he has carried on in this area since 1899. He has largely added to the previous knowledge, and particularly in respect to the cherty rock of Studley and Arngrove. 2 To this further reference will be made. In Holton Park the Corallian stone is said to lie all to the west of the Mansion, the house itself being partly on made ground. Clay was dug on the island surrounded by the moat, the site of the old Hall. Pieces of cherty sandstone occur in some of the fields to the south of Holton Wood. At Holton Rectory Oxford Clay was proved to a considerable depth. The following record of a wellsunk to the south of Church Farm Moat was noted by J. H. Blake in 1897 : Ft. in. f Brown sandy and loamy soil 2 I Brown sandy oolitic loam with irregular patches and seams of grey clay 5 n . i Rock band ... ... ... ... ... 4 Corallian -j Brown and grey clay 3 j Hard yellowish -white speckled cherty rock, called "Pendle" by the well I sinker: with Pleuromya 4 6 n f A m f Blue sandy and shaly clay, with band of rock \ 2 ft. thick, and large Gryphcca dilatata. . . G The strata appeared to dip towards the north-east. The cherty rock above noted is evidently the same as the Arngrove Stone. The boundary of the Corallian and Oxford Clays in the area north-east of Holton is very indefinite. The presence of Corallian clays is indicated in many spots by the abundance of Exogyra nana, while here and there large examples of Gryphcea dilatata are suggestive of the upper part of the Oxford Clay, in which these forms are usually abundant. From Holton through Waterperry, Worminghall, and Ickford the only sections are in ponds and ditches. The soil on the Corallian tracts is of variable texture, being here and there sandy and loamy, elsewhere clayey, but in .general It is a " deepish loam." 1 Quart. Journ. Geol. Soc., vol. xxxiii., p. 311. 2 Quart. Journ. Geol. Soc. y Ixiii., p. 29. CORALLIAN. AMPTHILL CLAY. 41 It was the opinion of Mr. T. R. Polwhele, who was engaged on the earlier Geological Survey, that along this belt there were argillaceous equivalents of the Lower Corallian Beds; while Prof. Green suggested that these clayey beds might be the equivalent of the Tetworth (Ampthill) Clay described by Prof. Seeley. 1 Lists of fossils from Ickford, Worminffhall, and Oakley were given by Prof. Green, but the particular localities and horizons were not sufficiently distinguished. At Worminghall, especially on the north side of the village, the ground has been dug up in places in " hills and hollows " as if for stone-layers. In this neighbourhood, blocks of Corallian stone are brought to preserre entrance tracks to fields, and they are strewn about the approaches to ponds. On the whole the ground is clayey cracked and fissured in dry weather and the soil is a brown loam, stiff in some places, lightened elsewhere, as on some of the allotment grounds, by sandy and gravelly patches in the soil. The soil is in part due to the decomposition of grittj and calcareous layers and stiff bluish and brown clay, with Exogyra and bits of large Gnjphcea, as seen along the ditch on the north side of the road from Worminghall to Shabbington, north of Little Ickford. Some of the hard beds from which water is obtained have probably become decomposed along their outcrop. South of Oakley, at the end of the lane east of Shabbington Wood and north of Houndsditch Barn, I obtained Alectryania gregaria (J. Sow.), Etcogyra sp., Gryphcea dilatata J. Sow., and Ostrea (fragment). Cherty sandstone occurs in a field south-east of Pasture Farm, west of Oakley. H. B. W. Studley and Boarstcdl. At Studley " a sort of argillaceous chert," which appears to have been first noticed by Buckland, was described by Prof. Phillips as containing Ammonites, Pinna lanceolata, &c. According to Prof. Green " This bed runs with a good escarp- ment by Arngrove Farm to the north of Gravel Pit Farm, beyond which point we lose sight of it altogether. It dips gently to the east, but whether it runs under the clay beds to the east of it, or passes into a clay, it is not easy to say. Immediately below this stone we find Oxford Clay with GrypJiom dilatata, and it is therefore without doubt the bottom bed of the Calcareous Grit." He recorded from it Cardioceras cordatum (J. Sow.), C. vertebrale (J. Sow.), Pecten fibrosus J. Sow, &c. 2 Mr. A. Morley Davies has applied the name Arngrove Stone to the cherty rock, as " the chief present diggings are near Arngrove Farm, and as this is the only locality from which any abundance of fossils can be obtained." 3 It will there- fore be convenient to adopt this name for local use. Mr. Davies has given detailed descriptions of the rock. The ordinary Arngrove Stone was observed by him " to be studded with innumerable minute ellipsoidal bodies, mostly of a translucent blue, but with everywhere some of an opaque white. 2 Green, Geol. Banbury, pp. 44, 45. Geol. Banbury, pp. 44, 45. 3 Quart. Journ. Geol. Soc., Ixiii., 1907, pp. 37, 38. 42 MIDDLE OOLITES. ... It is neither calcareous nor purely argillaceous . , [and] as a whole, is very light and porous, absorbing water very readily." Under the microscope he found the grains " to agree exactly in size and shape with the globate spicules of the tetractinellid sponge, Rhaxella perforata, described by Dr. G. J. Hinde from cherts in the Lower Calcareous Grit of Yorkshire." Mr. Davies further observed: "In one place only at a pond-digging at the Warren Farm, north of Studley this rock undergoes a remarkable change, becoming a limestone, though still exhibiting the characteristic structure." Omitting the more doubtful forms, the following revised list of fossils from the Arngrove Stone was published by Mr. Motley Davies 1 : Cardioceras cordatum (J. Sow.) ... ... ... D S P vertebrale (J. Sow.) D S P Alectryonia gregaria ? (J. Sow.) ... ... ... D Area quadrisulcata (J. de 0. Sou .) Avicula insequivalvis J. Sow. ... ... ... S ovalis Phil D Exogyra nana ( J. Sow.) ... ... ... ... D Goniomya literata (J. Sow.) P v.-scripta (J.Soiu.)... ... ... ... D S Lucina crassa ? (J. de C. Sow.) D Modiola bipartita J. Sow D S P cuneata J. Sow. ... ... ... ... P imbricata J. Sow. ... Pecten fibrosus J. Sow. ... ... ... ... D S lensJ. Sow D Perna quadrata J. de C. Sow ... ... ... Pholadomya sequalis J. de C. Soiv D S obsoleta Pkil , P Pinna Ian ceolata J. Sow. ... ... .. D S mitisPMZ Pleuromya recurva (Phil.) D P Trigonia clavellata ? (J. Sow.) D Serpula D S Bhaxella perforata ? flinde D D. Collected by A. Morley Davies. S. ,, Geological Survey. P. Recorded by John Phillips. Mr. Davies was enabled to observe the precise relation of the Arngrove Stone to the Oxford Clay in a well-sinking at the northern end of Studley Tillage, in September, 1899, the measurements given being approximate 2 : Soil and rubble of Arngrove Stone 3 Arngrove Stone 2 Keddish-brown sandy clav : fish-tooth, Alectryonia fragments, &c 3 Argillaceous limestone less than 1 Clay, very black and stiff: Gryphcea dilatata, Cardioceras cordatum at least 10 19 Between Beckley and Studley a deep valley connecting Ot Moor with the Thame basin, cuts off the Corallian rocks 1 Quart. Journ. Geol. Soc., Ixiii., p. 43 ; see also E. T. Newton, Free. Geol. Assoc., xx., .ssoc., xx., p. 127. 2 Quart. Jour.n. Geol, Soc., Ixiii., p. 40. COR ALLIAN. ARNGROVE STONE. 43 from the corresponding strata to the north-east ; and when they are encountered again it is found that their character has completely changed. The escarpment, indeed, overlooking the Ot Moor plain, though lower than elsewhere, is still a conspicuous feature from Studley to the north of Muswell Hill beyond the limits of the district. But only an insignifi- cant band of cherty stone 6 feet or less in thickness represents the 70 feet of strata at the top of Beckley Hill. There is no longer a continuous plateau of rock resting on Oxford Clay, but it is cut through by streams which, rising partly in the sands of Muswell and Brill, and partly in the plateau itself, have separated the rock bed into seven or eight outliers with valleys of greater or less depth in the Oxford Clay between. Further east the same bed is traceable continuously with clay- land on either side, from near Gravelpit Farm north of Boarstall, through the village, and southward past Slattery Farm, where it is lost sight of. It is clear from the manner in which the outcrop runs in V shapes up the brook-valleys, that this rock forms a gently inclined plane at the base of the clays to the east, which will be described later on under the name of Ampthill Clay. The place of the rock bed in the geological sequence is clear from its lithological character, its fossil contents, and its geographical distribution. In character it resembles almost exactly the basal beds of the Calcareous Grit at Stanton St. John. The fossils are extremely abundant, and include characteristic Lower Corallian forms. (See p. 42.) The clay immediately below the escarpment of the rock is full of the Gryphcea dilatata which characterises the top beds of the Oxford Clay. Hence there is little doubt that the Arn- grove, Studley and Boarstall stone is the dwarfed representa- tive of the Lower Corallian. There are but few sections. The rock is generally broken up into small fragments by surface weathering, and is locally called " gravel." A large pit near New Arngrove Farm (one-third of a mile south-east of the Old Farm) formerly supplied road-metal for the district. A quarter of a mile north of Studley Village, on the escarpment edge, there is a section by a pond showing 6 ft. of cherty sandstone with partings of clay. A few other places where the same rock may be seen by the side of ponds may be enumerated without further description : Studley Priory Park, close to the road. Road-side, half a mile north-east of Studley Village, opposite farm house. 200 yards south of same farm. Warren Farm. Common by New Arngrove Farm. Half a mile N.N.E. of New Arngrove Farm, near the road. One third of a mile W.N.W. of Boarstall Church. South of Decoy Pond, Boarstall. One third of a mile west of Gravelpit Farm. Holt's Farm. By moat south of Boarstall Tower. Half a mile south-east of Boarstall Church. Pasture Farm near Dane's Brook. South- west of Shabbington Wood. At Pasture Farm the rock is thrown down to the south-west by a small fault. At all these places two or three feet of broken rock can be seen, the water in the ponds being held up by the Oxford Clay below. On the east side of the outcrop of Calcareous Grit the ground is all clay up to the Portland Sands of Muswell and 44 MIDDLE OOLITES. Brill Hills. From Boarstall to the Thame the landscape is one of low relief, nowhere raised far above the streams which traverse it from north to south. Here and there slight ridges running approximately parallel with the outcrop form con- spicuous features. They are probably caused by thin stone- beds in the clay which permit the outflow of water. The moist -green pastures which prevail here present the strongest con- trast to the wide arable tracts of the Corallian plateau. As the clay at Boarstall follows with evident conformity the thin bed of Calcareous Grit, it occupies a position in the sequence of strata corresponding to higher beds of the Coral- lian formation. This is confirmed by an examination of its fossil contents. At the brick-pit of the Brill Brick and Tile Company, one mile north-east of Brill, there is the following section 1 : Ft, IT' ^:/i. m f Blue clay with Saurian bones 12 Kimeridge Clay { Pale cem ent-stone band 1 Amnthill Clav I Dark shaly cla ^ with Belemnites, oyster Jay i beds and many crushed fossils 6 The following fossils were obtained by Mr. Woodward and Mr. Lamplugh 2 : From the cement-stone band and higher beds: Plesiosaurus (vertebra), Pliosaurus (vertebra), Reineckia pseudomutabilis ? (De Lor), Belemnites nitidus Dollf., Pleuromya recurva (Phill.), Pholadomya cequalis J. de C. Sow. From the Lower Beds: Cardioceras excavatum (J. Sow.), Area sp., Gryphcea dilatata J. Sow., Ostrea discoidea (Seeley, M. S.) Kitcbin, and Serpula tetragona J. de C. Sow. Here there is a regular succession from the Kimeridge Clay downwards into clay containing forms characteristic of the Corallian Oolite, from which it is clear that while the coral banks so widely distributed in the Middle Oolitic forma- tion were growing in the western region, many other life- forms flourished in the deeper waters where the accumulation of argillaceous sediment was continuous from the close of the Great Oolite period to that of the lower Portland Beds. In the country between Boarstall and the Thame there are no sections, but the little oyster Exogyra nana, as before mentioned, may be easily found in the ploughed fields near the base of the formation, and has been invaluable in tracing the boundary. The upper boundary, however, is difficult to determine, and in the absence of sections on the west of Brill it has been necessary to use the succession in the brick- pit described above as a guide. Here the cement-stone band, which may be taken as a convenient line of division, forms a very marked feature at the base of the Kimeridge Clay slope, owing, probably, to the fact that it is the only pervious stratum within a considerable thickness of clay beds. The Kimeridge Clay stretches upwards 80 or 90 feet to the little 1 See also section by A. Morley Davies, Quart. Journ. Geol. Soc., Ixiii., 1907, p. 30, and Proc. Geol. Assoc., xx., 185. 2 These were identified in the Paleeontological Department of the Geological Survey. CORALLIAN. AMPTHILL CLAY. 45 Portland outlier on Rids Hill, east of Brill. Applying these data to the west side, it is found that at about the same distance below the Portland Sands of Muswell Hill, there is a very marked feature where water oozes freely from the clay. There is evidently a water-bearing stratum, and though it may not be the cement-stone bed of Brill brick-pit, it is at nearly the same horizon. The foot of this slope has accordingly been taken as the boundary of the Ampthill and Kimeridge Clays. Further south the features become indistinct, and the thickness of the two clays, judging from their vertical and horizontal extent, is much reduced. This apparent irregularity may, however, be due to the greater inclination of the strata or to a small fault of which evidence could not be obtained. The physical features no longer serve as guide, owing probably to the inconstancy of the hard bands in the clay. The base of the Kimeridge Clay, west of Brill Hill, has perhaps been drawn too near the Portland outcrop, allowing too small a thickness for the formation; but this appeared the most natural position to draw the line judging by the nature of the ground. In the cuttings for the new line of Great Western Railway, north and south of Rushbeds Wood, between Ashendon and Ludgarshall, north-east of Brill, about 25 feet of Ampthill Clay with bands of pale hard marl and argillaceous limestone, have been exposed. The lowest layers contained Exogyra nana and spines of Cidaris, as observed by Mr. Morley Davies. 1 1 Proc. Geol.Assoc., xx., p. 184. 46 UPPER OOLITES. CHAPTER V. UPPER OOLITIC ROCKS. BY H. B. WOODWARD, WITH NOTES BY T. I. POCOCK. KJMERIDGE CLAY. The Kimeridge Clay consists of dark grey and black shaly clay, with, septaria, and much selenite in places. The clay weathers brown at the surface. The beds are as a rule darker, and in mass more shaly, than the Oxford Clay, and their thickness probably nowhere exceeds 100 feet in the area. The Kimeridge Clay in general owes its dark tint partly to carbonaceous matter, partly to bisulphide of iron. 1 The decomposition of pyrites by atmospheric agents leads to the formation of selenite, lime being present in the clay itself as well as in the fossils. In some cases the Oyster shells (0. deltoidea) have been converted into sulphate of lime, as noted by Dr. Kidd at Shotover. 2 The decomposition of the pyrites leads to the formation of limonite, which, in the case of the Headington quarries near Shotover, is washed from the Kimeridge Clay on to the Corallian stone beneath. 3 Mr. A. Morley Davies has drawn attention to the selenitization of belemnites from the brickyard at Kid's Hill, near Brill. 4 The best section of Kimeridge Clay is exposed in Chawley brickyard at Cumnor Hurst, where it is overlaid by Lower Greensand, Gault, and Drift in upward succession. The beds are extremely irregular, no single part of the section showing the full thickness. The Greensand fills deep hollows in the Kimeridge Clay, and extends down the slopes of Hurst Hill with a dip amounting to 30 in one case. In its turn it is cut into to a depth of about 15 feet by Gault and Drift. (See p. 80.) The following table gives the approximate thickness of the different strata, the measurements of the Kimeridge Clay being those of Sir. J. Prestwich : Ft. in. Drift ... Bedded gravel of quartzite, flint, &c., with sand... 10 f Dark bluish-grey clay with phosphatic nodules Gault < and fragments of the Ammonite Hoplites inter- (. ruptus. (Seep. 80.) 10 Lower f Coarse brown false-bedded quart zose sand with Greensand \ concretionary ironstone 20 1 G. Maw, Quart. Journ. Geol. Soc,, xxiv., p. 357 ; see also analysis by J. D. Kendall, Trans. JV. of Eng. Inst. of Mining Engineers, xxxv., p. 156. 2 " Outlines of Mineralogy," 1809, vol. i., p. 68. 3 See Report of Excursion of Geologists' Association to Oxford, 1869, p. 6 (separately printed ). 4 Quart. Journ. Geol. Soc.* IxiiL, 1907, p. 33. KIMERIDGE CLAY. 47 Ft. in. Pale grey sandy clay 2 Dark bluish-grey slightly calcareous clay, with greenish sandy seams, nodules of earthy lime- stone, and large septaria with Ammonites bi- plex* and lignite 18 Clay, with band of fossils, yielding *' PI esiosaurus," Am. biplex,* Pleurotomaria reticulata, Astarte, Cardium striatulum, Lima, Modiola bipartite, Kimeridge . Pleuromya recwrra, Pecten nitescens, Perna mi/- Clay ti/oides, Pinna lanceolata, Thracia depressa, Trigonia, and Serpula tetragona 14 Seam of clay laminated with white sand (Iguano- don-bed), with Camptosaurus [Iguanodon] Prest- wichi, Aptychus latus, Pleurotomaria, Astarte, Exogyra virgula (abundant) Trigonia, Lingula ovalis 3 Clay with large septaria, with Dacosaurus,Ichthyo- saurus, Pliosaurus, Astarte lineata 4 * Probably Holcostephanus palladaniis (d'Orb.). At Sandford, according to Mr. E. S. Cobbold, "a peculiar bright red earthy layer from 4 to 6 inches thick " occurred at the junction of the Kimeridge Clay with the Corallian Beds. From tbe clay he recorded vertebrae of Pliosaurus, good specimens of Bhynchonella inconstans and numerous crystals of selenite. 1 Besides the well-known section at Chawley Brickyard there are few sections of Kimeridge Clay in the western part of the district. It was formerly worked for bricks in the small outlier west of Marcham, but the pit is now overgrown. It has been frequently pierced at Abingdon and Radley by wells sunk to the water-bearing Corallian Beds below, but for the most part this low-lying tract is covered by river-deposits. In pits on the south of Foxcombe Hill the clay can be seen underlying the iron- sand. T. I. P. A boring at Bflldon House, March Baldon, carried out in 1883, proved the following strata, as noted by J. H. Blake, from data communicated by Mr. Edward Margrett : Thickness. Depth. Ft. Ft. [Portlandian] Yellow clay and sand about 35 35 ("Dark grey clay about 90 125 ] Rock 1 126 (.Grey clay 20 146 f Rock with veins of clay 20 166 I Rock with sand and numerous shell- -{ fragments 15 181 I Fine white sand ... 14 195 I Rock ... 1 196 Kimeridge Clay Corallian The following fossils were obtained and identified by Mr. E. T. Newton: From the depth of 40 feet Perisphinctes plicatilis (J. Sow.). < near to eupalus (d'Orb.). Exogyra. Protocardia striatula (J. de C. Sow.). Serpula. From the depth of 180 feet Exogyra nana (J. Sow.). Pecten fibrosus J. Sow. Glyphaea. Fish vertebra. Quart. Journ. Geol. Soc., xxxvi., p. 318. 48 UPPER OOLITES. The following fossils 1 were lately collected for the Geological Survey by Mr. John Pringle, from excavations in the Kimeridge Clay near the Viaduct over the Thames immediately S. of Abingdon Junction : Area longipunctata ? Blake. Astarte ? Exogyra virgula De/r. Lucina? Protocardia striatula (J. de C. Sou'.). Aptychus sp. Perispinctes rotundus ? (J. Sow.). Shotover Hill. The brickyards on the western side of Shotover Hill, near Headington, show the Kimeridge Clay resting on the Corallian rocks and overlain by Portland Beds. The thickness of the clay was estimated at 100 feet by Prof. Phillips, but only about 30 feet of it is exposed. It consists of bluish-grey and dark blue shaly clay, weathering brown at the top, with lignite and with a few layers of septaria and much selenite. (See p. 34.) Prof. Phillips noted that about 15 feet from the base there is a septarian band yielding RhyncJionella inconstans, &c. ; lower down there are layers of Ostrea deltoidea, and near the base Thracia depressa and Exogyra virgula are fairly abundant. At the base coprolites were first noticed by the Rev. H. Jelly. 2 Sowerby figured Ostrea deltoitdea from this locality, remarking that the fossils were known as " Heddington (Headington) Oysters." jfn addition to various Saurian remains, the following fossils have been recorded from the Kimeridge Clay of Shotover Asteracanthus ornatissimus. Hybodus acutus. Ischyodus Egertoni. Lepidotus- maximus. Holcostephanus pallasianus ["Ammonites biplex "]. Belemnites abbreviatus var. excentricus. Pleurotomaria reticulata. Astarte'ovata. Exogj r ra virgula. Ostrea deltoidea. Thracia depressa. Discina latissima. Rhynchonella inconstans. Serpula. Aptychus (Trigonellites). Prof. Phillips recorded Belemnites " g&planatus " [Z?. nitidu8\ from the upper part of the Kimeridge Clay at Water- stock, near Thame, and Wheatley, near Oxford, as well as from the Hartwell Clay. 4 The palatal teeth of fishes, more particularly those of Lepidotus \=Sph(Krodus gigas~], from the Kimeridge Clay, were described by old writers as Bufonites or Toad-stones, and were utili/ed in former times as ornaments, or as charms. 5 , * Numbered [Pr. 40094017] in the Geological Survey Collection. 2 Buckland, Tram. Geol. Soc., ser. 2. vol. iii., p. 232 ; see also Fitton, ibid., vol. iv.. p. 278; Phillips, Geol. Oxford, &c., pp. 329, 413, and Quart. Journ. Geol. Soc., vol. xiv , p. 238 ; and Hull, Geol. parts of Oxfordshire and Berk- shire, p. 10. 3 See " Jurassic Rocks of Britain," v., p. 168. 4 " British Belemnites," 1865, p. 128. 5 H. Woodward, Geol. Mag., 1893, p. 246. KIMERIDGE CLAY. 49 The brick and tile works at the western end of Wheatley Village, where Kirneridge Clay was worked, have long been abandoned. There, according to J. H. Blake (1898), the section showed 30 to 50 feet of blackish grey clay and shale. In the collection of Mr. James Parker, of Oxford, there is a specimen of Astarte hartwellensi* from this locality. At the present time an extensive clay pit is worked for brickmaking on the south side of the railway, north-east of Littleworth by Wheatley. Here the following fossils were obtained 1 : Ichthyosaurus (vertebra). Holcostephanus cf. pallasianus (d'Orb.) Pliosaurus (vertebra). Perisphinctes. Belemnites nitidus Dollf. Ostrea cf. duriuscula Phill. Plot mentioned in 1677 that at " Wliat elij Towns end, near the foot of the hill," some attempts had been made for coal. 2 H. B. W. Mr. A. J. Jukes-Browne noted the following section at the brickyard by the side of the high road a mile north of Great Milton: Ft. in. Sandy soil 3 Brown loamy sand from to 8 ( Dark blue clay 6 Grey argillaceous sand 3 Kimeridge j Hard blue sandy limestone 9 Clay i Fine grey sand about 12 inches, becoming argillace- ous and lilac-coloured and passing down into I strong blue clay 7 [The brown loamy sand may belong to the Shotover Sands, or Portland Beds, or may be Drift.] The blue clay contains Ammonites and Saurian bones, and at its base Protocardia strmtula, Pleuromya sp., and Exogyra sp., the first two in phos- phate like Potton fossils. The limestone weathers very sandy, but contains large Ammonites and other fossils. A. J. J.-B. Brill. At the brickyard north-west of Brill, clays were formerly dug beneath the Portland stone-beds, and numerous iridescent fossils were obtained. The clays belong in part to Kimeridge Clay and in part to the Lower Portland Beds (Hartwell Clay). (See p. 60.) Reference has been made to the brickyard of the Brill Brick and Tile Company on the eastern side of Brill (p. 44). It is outside the bounds of our area, and it will be sufficient to note that Mr. A. Morley Davies has recorded Aptychus latus (Park.), Exogyra virgvla Defr., from the higher beds of clay above two bands of creamy limestone. From these bands he records some Ammonites of doubtful species, also Pholadomya cequcdis J. de C. Sow., and Pleuromya recurva ii.). 1 Named in the Palaeontological Department of the Geological Survey. 2 Nat. Hist, of Oxfordshire, p. 57. 9813 5() UPPER OOLITES. CHAPTER VI. UPPER OOLITIC "ROCKS (continued-,. PORTLAND BEDS. I5Y H. B. WOODWARD, WITH NOTES BY H. H. THOMAS. This group consists most largely of sandy strata, with beds of limestone as well as sand and thin clay-bands in the upper part. The conventional division into Portland Sand and (overlying) Portland Stone appears applicable only to portions of this area, and even then it is better to use the terms Lower and Upper Portland Beds, 1 as both divisions contain beds of sand, and in certain tracts the Lower beds pass into a loamy clay equivalent to the Hartwell Clay. The Portland Beds are represented by one colour on the map ; but generally from Shotover Hill to Great and Little Milton the Upper and Lower Beds have been separated by a line. This is not, however, of uniform stratigraphic value. The Hartwell Clay is coloured the same as the Kimeridge Clay. In the area to the south and south-east of Oxford we find evidence of several outlying masses of Portland Beds, but it is not improbable that the rocks exposed at Great Milton are portions of a large mass continuous underground with those of Thame and Aylesbury. Shotover Hill. Shotover Hill, which lies to the east of Oxford, includes the commons of Cowley and Horsepath, and affords some famous sections of the Portland Beds. It is part of a straggling outlier stretching in a south-easterly direction to Garsington and Cuddesdon, and covered irregularly by two outliers of the Iron Sands. The old coach road to London passed over the summit of Shotover Hill, and the several groups of strata opened up from near Headington at the western foot of the hill to the " Iron Sands J? on the top, early attracted the attention of geologists. Especially noteworthy were the great " sand- bailers " or " giant ? s marbles " derived from the Portland Sands, some of these doggers beinsr from three to six feet in diameter and two feet or more in thickness. 1 See "Jurassic Rockss ftf Britain"" y., pp. 180, 181 j and preen, Geol, JSanbury, p. 46. PORTLAND BEDS. 51 The following is the general section at the western end of Shotover Hill: Shotover Sands. Portland Beds. P I I. f Sands with hard ferruginous bands, Trigonia, 20 or 30 ft | Whitish limestones, large Portlandian fossils. Cardium dissimile, &c. I Clays, loam and greenish sands. ^ ^ Rubbly glauconitic limestone, Pleurotomaria cf. 1 4 t. rngata Benett. J i Lydites. ^Blue and brown clay, with lydites and phosphates in f base of clay and top of sands, 3 to 5 f c. Yellow and greenish sands, slightly glauconitic, with " sand-bailers," h uge spheroidal doggers of calciferous sandstone, blue-hearted, and with small lydites, Peris- phinctes plicatilis -.? (J. Sow.), Exogyra sp., Lima, Lithodomus sp., Perna cf. mytiloides Lam., Phola- domya, Trigonia, &c., 20 ft. The full thickness of the lower sandy division is probably about 60 feet, while the overlying division may be from 40 to 50 feet. The total thickness of the Portland Beds at Shotover is probably rather more than 100 feet 1 ; but it is nowhere possible to measure the full thicknesses of all the subdivisions. The upper beds of Shotover yield the following fossils : Perisphinctes boloniensis (de Lor.) Cerithium portlandicum J. de C. Sow. Natica elegans J. de C. Sow. Cardium dissimile J. de C. Sow. Lucina portlandica J. de C. Sow. Ostrea expansa J. Sow. Pecten (Amusium) lamel- losus J. Sow. Trigonia gibbosa J. Sow. Among fossils from the lower beds the following have been recorded 2 : Perisphinctes pectinatus Phil. Pecten nitescens Phil. Pern a. Pholadomya turnida Ag. Pinna. Trigonia pellati de Lor. Fitton described the top layer as a "'very hard brown sand- stone, with a few Trigonice," and this was probably the bed from which Dr. Teall long ago obtained a specimen of Trigonia gibbosa var. dammiiana 3 : a form now spoken of simply as Trigonia damoniana de Lor. The suggestion made with reference to the horizon of the fossil receives confirma- tion from the researches of Mr. Lamplugh. (See p. 68.) 1 See also A. M. Davies, Proc. Geol. Assoc., xvi. ,27. 2 Phillips, Quart. Journ. Geol. Soc., xiv., p. 238, and Geology of Oxford, &c., pp. 326,413, 421 ; see also Hull, Geol. parts of Oxfordshire and Berkshire, p. 12 ; andJ. F. Blake, Quart. Journ. Geol. Soc., xxxvi., p. 213, and Plate VIII. 3 Fitton, Trans. Geol. Soc., ser. 2. iv., pp. 275, 278; Teall, " Potton and Wicken, Phosphatic Deposits," pp. 32, c., 1875; H. B. Woodward, "Jurassic Rocks of Britain," vol. v., p. 218. 52 UPPER OOLITES. More recently Mr. John Pringle has collected (for the Geological Survey) the following Portlandian fossils from the western end of Shotover Hill : Upper Pit, in ferruginous sandstones. [Pr. 3985-3988.] Lucina portlandica J. de 0. Sow. I Trigonia damoniana ? de Lor. Modiola boloniensis ? (de Lor.) \ Lower Pit y in sands ivith greed doggers. [Pr. H953-3977.] Pecten sp. Perna rnytiloides Lam. Pholadomya rustica Phill. cf. Placunopsis lycetti de Lor. Pleuromya tellina Ag. sp. Protocardia morinica (de Lor.) Perisphinctes giganteus ? (J. Sow.) Area cf. catalaunica de Lor. ,, cf. rhoraboidalis Contej. sp. cf . Astarte rugosa, ( J. de G. Sow.) Corbicella ? Exogyra bruntrutana ? (Thurm.) Lucina portlandica J. de G. Sow. Ostrea expansa J. Sow. sp. Pecten cf. morini de Lor. Lor.) cf. morinica (de Trigonia muricata ? (Goldf.) sp. Serpula sp. In the course of observations on the fauna of the Shotover Sands, Mr. Lamplugh saw reason to discriminate between the ironstone-beds with freshwater fossils, and those with marine forms ; the latter (as elsewhere mentioned) proving on Shot- over Hill to be truly Portlandian. 1 From the rock-specimens gathered by him the following notes have been drawn up. METASOMATI CHANGES IN THE PORTLAND STONE OF SHOTOVER. BY H. H. THOMAS, M.A., B.Sc. The normal Portland Stone is in general a shelly and oolitic limestone, fairly pure in composition ; but under the influence of percolating waters it has locally undergone extensive changes. The most usual change is that of partial, or more or less complete, silicification, but in many cases much of the calcium carbonate has been replaced by ferruginous compounds. In the latter case, as mentioned above, this change has caused the altered Portland Stone to be confused with the freshwater ironstone of a higher horizon. In the neighbourhood of Shotover Hill remnants of the Portland Stone are met with which have been all more or less changed from their original character by the process of silicification. On the south side of the hill a rock occurs which, under the microscope, is seen to be made up of closely packed oolitic grains set in a matrix which is almost wholly silicified. The oolitic grains themselves show all stages from partial to complete silicification, but in some of the specimens which are less changed they still consist in paxt of carbonate, and retain their original concentric structure. 2 At the same time, in the more completely silicifie4 1 Rep. Brit. Assoc. for 1904 (Cambridge^, p. 548. ?See also " Jurassic Rocks of Britain," v., pp. 186, 187, PORTLAND BEDS. 53 rock, the outline of the grains is still distinct, being emphasised by dusty iron ores. The change in the oolitic grains seems to have taken place in two ways, both* by the replacement of the calcite by chalcedonic silica, and by the growth of quartz, probably on minute clastic grains of that mineral which formed the nuclei of -the oolitic structures. The quartz has grown in perfect optical continuity, but not in such a manner as to show crystal outline, the result being an irregularly-shaped mass which often entirely or only partially encloses the oolitic grain. At the same time the original outline of the oolitic structure may be traced through the quartz by means of the ferruginous inclusions. Other examples of the Portland Stone, such as those from a sand-pit east of the western brickyard, show that nearly all the oolitic grains in these cases have been replaced by crystalline quartz, with irregular or subrounded outline. That this silicification has proceeded from the centre is shown by the fact that many of the oolitic grains are not completely replaced, the outer margin, or part of it, being still formed of carbonates. From the above considerations it is obvious that all the larger quartz grains in these silicified oolites are of secondary and not of clastic origin. Occasionally the rock is highly ferruginous, and then it is seen that the iron was introduced, as was the silica, from without, and it is evident that those parts only which had not been previously silicified, both of the matrix and of the oolitic grains, have been replaced by iron oxides : probably originally deposited as carbonate. It is assumed, therefore, that the iron-bearing waters followed those carrying silica. In some examples it seems that most of oolitic grains had clastic quartz nuclei, and therefore there was a tendency to the formation of quartz rather than of chalcedonic material. In the rocks collected from a sand-pit on the eastern side of the reservoir, most of the oolitic grains are replaced by masses of secondary quartz, and these are set in a matrix con- sisting chiefly of iron oxide, causing the rock to present all the appearance of a ferruginous grit. It is evident that in this case we are dealing with a rock which, without regard to less changed specimens, would have been classed as original in character, whereas in reality all its components are of secondary origin. It is suggested that other so-called ferruginous grits may H. H. 1. During the construction of the railway through the hill between Horsepath and Wheatley, a section of the strata passed through was drawn by Mr. Thomas Codrington. A copy of this is here given (Fig. 7). Two bands of stone, 4 feet apart and l\ to 2 feet thick, generally very hard, were constant throughout the cutting, dipping 1 in 110 or 1 N.N.W. These were full of fossils, and the upper layer was in parts loose sandstone passing into compact limestone. 54 TIPPER OOLITES. FIG. 7. Section along line of railivay betiveen Horsepath and Whoatley. (T. Codrington.) 5. Shotover Sands. 4. Yellow sand Limestone Clay 1. Strong clay C Upper Portland Beds. V Lower Portland Beds. * Kimeridge Clay. The Lower Portlandian Beds (3) were noted by Mr. Codrington as " dark sandy clay " ; they are continuous with the sands with great doggers of the Shotover section. It is to be remembered, however, that these Lower Portland Beds are represented by loamy clays at Brill, and in the inter- mediate area at Eed Hill, Forest Hill ; strata that represent the Hartwell Clay of Aylesbury, but have not been separated from the Kimeridge Clay on the Geological Survey map. Springs are thrown out by the Kimeridge Clay at various places around the Portland outliers, and other springs are thrown out by the clay-band in the Portland Beds. To the north-east of Hill Farm, Horsepath, there is a spring thrown out by the clay in the Portland Beds. Above these are yellowish or orange sands, and ferruginous stones are thrown out of the rabbit-burrows. Here were found Trigonia damoniana (deLor), and other fossils, also cherty rock and whitish loamy sand. The following record of a well dug in 1893 in Horsepath Parish, by the Windmill, south-west of Wheatley, was noted by J. H. Blake (1897) : Thickness. Depth. Ft. in. Ft. in. Shotover / Brown sandy sOil 3 3 Sands \Whiteandiron-stainedsand ... 14 9 17 9 f Red sand with black pebbles (size of hazel nuts) 1 19 Seam of yellow pipe-clay ... ... 3 19 3 Nodules of ironstone 6 19 9 Hard white stone 60 25 9 Iron-ore 10 26 9 Greensand (similar to that used for moulding purposes) 10 11 37 8 Hard grey stone 16 39 2 Greensand with hard concretion- ary masses of stone 1 ft. by 1| ft. 10 49 2 Hard rock the upper 4 feet very j hard ; the lower part softer, with concretionary masses, very fossiliferous, Trigonia, &c. IWater 6 11 56 1 | Reddish-brown clayey loam ... 2 10 58 11 Portland Beds The presumed overlap of the Shotover Sands on to the Kimeridge Clay shown on the old Geological Survey map at Littleworth, near PORTLAND BEDS. 55 Wheatley, was ascertained by Mr. J. H. Blake in 1897 to be erroneous? the prolongation of the outlier being due- perhaps to the occurrence on the north of the old Wheatley and Shotover road of " a patch of choco- late coloured sand with ironstone, overlying Kimeridge Clay." As Mr. Blake remarked : " This is in all probability drifted material ; but had it been of the same age as that on the high ground to which it has a very similar appearance on the surface of the field it ought to have been shown as an outlier, not connected." 1 A similar downwash of sand, probably Portlandian, occurs on the hill one quarter of a mile north-west of Shotover House. Forest Hill. The outlier of Red Hill by Forest Hill was originally mapped as " Lower Greensand " on Kimeridge Clay ; but during the re-survey traces of Port- land Beds were proved to occur. Their presence at the new Cemetery and on the eastern side of Eed Hill was inferred in 1904 ; and definite evi- dence was subsequently obtained in a trench made during building- operations for Mr. W. C. Tyndale, where a fragment of a large Ammonite was found. The section on the hill was as follows : Shoto C Red ironstone 5 or 6 feet. < White and brown sands and occasional iron- Sands I stone 6 feet. Portland J Glauconitic limestone with Holcostephanus cf. Beds \ pallasianus (d'Orb.). The ironstone is probably faulted in the central part of the hill, as the strata at the south-eastern end are on a level distinctly lower than those of the north-western portion of the hill. At the spring south-west of the semi-circular plantation on Red Hill, soft mealy sands and loams were exposed here probably faulted against the Kimeridge Clay. Cuddesdon and Garsington. North-east of Cuddesdon Palace a small quarry showed the following section : Irregular pipes of brown loam and sand, f Oolitic and tufaceous-looking rock, crumbly, with Natica sp., also Trigonia incurva ? Portland j (Benett) at top. The beds are stained in Beds j places by pockets of overlying ironsand ... 1 or 2 feet. | Pale oolite, more or less shelly, with Ostrea ; L used for building-purposes 10 feet. The upper bed here would appear to correspond in character with the " Malm " above the Portland Stone at Garsington, that was referred to the Purbeck Beds by Fitton. 2 The above-mentioned fossils, however, indicate that the bed is Portlandian. In Fitton's time the principal stone-pits at Garsington were "in tbe western escarpment of the hill north of the village, overlooking the low ground about Langcomb and Cowley " ; Langcomb being probably the valley between Easington and Horsepath. Prof. Hull noted a section, one mile north of Garsington, showing white oolitic limestone (Portland Beds) overlaid irregularly by the Shotover Sands. 3 The limestone was much eroded at the upper surface, and con- tained Trigonia, Pinna, Ostrea expansa, &c. i Letter to H. B. Woodward, dated Oxford, November 30th, 1898. * Trans. Geol. Soc., ser. 2, iv., p. 277. 3 Geology of parts of Oxfordshire and Berkshire, p. 11. 50 UPPER OOLITES. Mr. Morley Da vies has also noticed that the Portland Beds to the north- west of Garsington near the " Red Lion " comprise 1 : Ft. in. Yellowish and bluish green sand about 16 Shelly sands passing into sandy limestone ... 1 More massive limestone ... ... ... ... 3 6 These beds appeared to him to occur but little above the Kimeridge Clay, but the evidence was not clear, and in some respects the strata compare better with the Upper Portland Beds. About half a; mile to the north-east he observed in a trench the basal Portland Sands about 35 feet thick, capped by the " lydite bed," which he found to consist of black pebbles, mostly of chert, but including spherulitic felsite and phosphatisedbone. Above this pebbly layer there was about 12 feet of glauconitic limestone (pebbly at base), with Cardium dissimile ; then 9 feet of sand, with thin course of stone, and traces of higher lime- stone beneath the Shotover Ironsands. Toot Bcddon. The possible occurrence of Portlandian strata at Toot Baldon was first suggested by John Phillips. Thus 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 feet 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, Cardium striatulum, Thracia depressa, Pecten arcuatus, Corbula, and wood ; and he suggested that the bed might be " perhaps the first stage of a change towards the Portland series." 2 At a later date, when the first Geological Survey was in progress by Prof. Hull, some fossils were found in " the road- cutting at Toot Baldon," during a tour of inspection with Prof. Ramsay and Mr. Etheridge. The discovery is thus mentioned : 3 " At this place marine shells (Ammonites Deshayesi 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 specimens are not in the Museum of Practical Geology, and they appear not to have been preserved. This is unfor- tunate, as subsequent observations have rendered most doubtful the identifications of the species. When Phillips afterwards re-examined the place he stated his results as follows 4 : "Here [at Toot Baldon], some years since, on the very summit I found sandy and stony beds in small quantity and not well exposed. They yielded me no fossils ; but my friends of the Geological Survey have since visited the locality, and obtained an Ammonite which they believed to be of the group of A. Deshayesi [on the authority of R. Etheridge]. I lately re- examined the spot, now less exposed than ever, without finding anything 1 Proc. Geol. Assoc., xvi., 19. 2 Quart. Jovrn. Geol. Soc. xvi., I860, p. 310; see also H. B. Woodward, " Jurassic Rocks of Britain," vol. v. pp. 167, 169, 217. 3 The Geology of parts of Oxfordshire and Berkshire, Mem. Geol. Survey, 1861, p. 15. 4 Quart. Journ. Oeol. Soc. xvi., p. 311; and H. B. Woodward, "Jurassic Kocks of Britain," vol. v., p. 217. PORTLAND BEDS. 57 satisfactory. But on proceeding down the sloping road to the eastward, I perceived the clay to be there also covered by ferruginous bands, and commenced a persevering search for fossils. I made a considerable exca- vation, and obtained several shells, especially a Mi/a, Pecten, Cardiiim, Trochus, and an Ammonite which appears to be of the group of A. poly- plocus, A. triplicatus, and A. giganteus. The mass is sand and sandstone with small black pebbles, and stained very brown by oxide of iron. It rests immediately on the Kimmeridge Clay, probably on the very top or upper layers." In the concluding paragraph of the same paper, Phillips adds " the Geological Survey has had only a glance at an Ammo- nite, which was supposed to be A. Deshayesi, on the summit of a hill near Oxford, from which I obtained quite a different Ammonite, apparently of an Oolitic group, with other shells not sufficient to authorize the adoption of their sandy matrix into the Cretaceous family." In his later " Geology of Oxford " (p. 420), however, Phillips classed the sandy beds of Toot Baldon with the Low^er Creta- ceous. Some further specimens wore obtained during the re-survey by our colleague the late J. H. Blake, who while mapping this area found some blocks of more or less cherty sandstone with casts of fossils, in a field 700 yards 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." 1 It was noted by Mr. Lamplugh with regard to these speci- mens, that the cherty blocks since found on the slopes of Shotover Hill prove to be altered Portlandian rocks, as already described (p. 52) ; and that cherty beds are not known to occur elsewhere in the Lower Greensand of this district. 2 There- fore, in view of the unsatisfactory nature of the palaBonto- logical evidence, the question as to the age of the sandy deposits which directly overlie the Kimeridge Clay around Toot Baldon and March Baldon, was held by him to be an open question. It should, however, be mentioned that during his examina- tion of the strata between Culham and Toot Baldon, Mr. Lamplugh had observed a change in the lithological character and colour of the beds northwards from the neighbourhood 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 Hampden, and of great portion of Nuneham Park. Meanwhile the Lower Cretaceous strata in this area had been described in 1898 as the " Toot Baldon Beds," by Mr. A. Morley Davies ; although he admitted the possibility that there might be a trace of the lower sandy beds of the Port- landian at Toot Baldon. 3 1 Summary of Progress, Mem. Geol. Survey, for 1900, p. 120. The speci- mens referred to are not preserved in the Survey collection. 2 The cherty layers mentioned as occurring in the Shotover Iron-sand and Ochre Series (see Phillips, Geol. Oxford, pp. 414, 415) were evidently at the base of the series and probably Port.landian. 3 Proc. Geol. Assoc., vol. xvi., p 45. 58 UPPER OOLITES. During the early part of the year 1907 Mr. Davies very kindly sent to the Museum at Jermyn Street, for determina- tion, some fossils which he had collected in 1903 from sandy strata in the lane-cutting south of Oldhouse Farm, Toot Baldon. The specimens include a clavellate form of Trigonia not sufficiently perfect to be identified specifically; also Cyp / rina?,Exogyra thurmanni? (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 obtained his specimens, other fossils of identical matrix were obtained in the neighbourhood, some of them of similar species to those found by him in the Lower Portland Beds at Shotover Hill (see p. 52), and likewise pre- served in rock of similar lithological character. Mr. Pringle ascertained that in the fields east of March Baldon and at Baldon Row, highly fossiliferous " doggers " of sandstone are frequently met with at a depth of 6 to 8 feet 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. Larnp- lugh. A line separating the Portland Beds and Lower Greensand has consequently been drawn on the map, in accord- ance with the evidence that could be gathered of the distribu- tion of the different sandy deposits between the definite areas of Lower Greensand on the south, and of Portland Beds on the north. The following fossils were collected from the Portlandian Beds by Mr. Pringle: Garden of house 400 yds. W.S.W. of St. Lawrence Church, Toot Baldon. [Pr. 3978-3984]. Astarte rugosa ? (J. de C. Sow.) cf. Lucina portlandica J. de C. 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 C. Sow.) Pecten morini de Lor. Cyprina ? nitescens Phill. Leda ? sp. Ostrea sp. Perna sp. It should be mentioned that Mr. Pringle noted the strong resemblance 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 Serpula and a specimen near to Isodonta iongior Blake. 1 Great Milton and Great Haseley. A mass of Portland strata appears from beneath the cover- ing of Cretaceous rocks at Great and Little Milton, and the stone-beds have been worked below those rocks at Great Haseley and near Great Milton. 1 These fossils [Pr. 4004-4007] are preserved in the Museum at Jemiyn Street. PORTLAND BEDS. 59 In a quarry on the eastern side of Great Milton the follow- ing beds were to be seen in 1886 (see also p. 72)-: & Section at Great Milton. ^Il^SffiSSi 3 Shotover Sands. Ft. (6. Brown loam (used for brickmaking) up to ... 4 i 5. Sand with bands of white and ochreous clay, j with lignite 3 to 6 ] 4. Buff and white false-bedded sand with ferru- ginous layers and concretions; and at base, lydite pebbles and ironstone 3 to 6 ( 3. Rubbly bed of sand with hard nodular calcare- ous sandstone and chert ; Ostrea expansa. This had the appearance of a remanie bed 3 Oto4 j 2. Clayey and shelly layer with hard nodules ... { 1. Hard and soft calcareous sandstone (free- stone), cherty in places, passing down into grey and greenish sandy oolitic limestone (burnt for lime) ; with Ostrea, Perna, Tri- gonia gibbosa : seen to depth of 6 From the workable stone-beds in this district Prof. Blake recorded :- in. Portland Beds. Lima rustica. Ostrea expansa. Pecten lamellosus. Pleuromya tellina. Trigonia gibbosa. incurva. From the higher rubbly beds he obtained Cerithium portlandicum, Perna, &c. In these layers some of the lumps had " the appearance of rolled masses of stone, so corsolidated by similar material that the separate pieces are scarcely recognizable." 1 The following section at Great Haseley (Fig. 9) was noted in the old pit on the north of the village, near the school house : Ft. I 5. Ironstone ......... ......... 4 4. Oehreous and white clays, with bands of iron- stone and ferruginous sand ; more sandy to- wards base and false-bedded ......... 15 3. Laminated clay and ironstone ... ... ... P 2. Fine mealy calcareous sand ......... 1. Shelly earthy and sandy oolitic limestone : Tri- gonia, &c ................... 3 The top-beds for a depth of 5 or 6 feet were contorted and nipped up. Prof. Hull noted the presence of small pebbles of lydian stone in sandy oolite, which rested on 2 feet of white sand. Above the oolite there was then exposed 5 feet of chalky limestone, with Ostrea expansa, &c. This bed, he observed, was sometimes eroded. 2 It is the layer called " Curl " by Fitton. (See p. 73.) 1 Quart. Journ. Geol. Soc., xxxvi., p. 214. 2 Geol. pares of Oxfordshire and Berks, p. 11; See also Htton, Trans. Geol. Soc., ser. 2, iv., p. 276 ; and J. F. Blake, Quart. Journ Geol. Soc., xxxvi., p 213. Shotover Sands Portland Beds in. 60 TIPPER OOLITES, FIG. 9. Section at Great Haseley. (For references see p. 59 I was informed that all the best stone at Haseley had been worked out. The beds are very variable and the good stone is not of great thickness. Portland Stone from Portland is now introduced for tombstones, &c. Between Great Milton and Little Milton, and east- wards, there is a large area of Portland Beds with few sections. The ground is flat and open, with large fields mostly under arable cultivation. The soil is a brown loam and sand with occasional pieces of limestone. Where actual evidence is obtained the rock is seen to consist of the crumbly oolitic and sandy limestone and calcareous sand, visible in pits east of Great Haseley, and by the road a quarter of a mile south- west of the church. 1 There were formerly many quarries, but the hollows are mostly covered with soil and overgrown, or filled up with soil and under culti- vation. There were old pits by Canker Leaze, west of Little Haseley, and by the plantation to the north. Other pits with much sand and decomposed stone are to be found north- east of Little Milton, some used as receptacles for dust and rubbish, and thereby liable to pollute the underground water. East of Haseley Court, on the left bank of Haseley Brook, between Peg's Farm and Upper Standhill, there is a series of old pits that were opened up in Portland Stone and Sands. A well at Haseley Court was excavated in stone-beds. BriU. In the outlier at Brill the boundary drawn at the base of Portland Beds is in reality at the junction of the Upper Portlandian and the Hartwell Clay (Lower Portlandian), which merges downwards into the Kimeridge Clay. No practical purpose would have been served by attempting to discriminate the Hartwell Clay. The junction thus taken is marked by the outflow of numerous springs, which issue at the base of the glauconitic limestones with Cdrdium di-s simile, Perna, and other Portlandian fossils. At the old brickyard, west of Springfield Farm, and in an adjoining quarry on the north-western side of the hill, the following beds were exposed: Ft. in. Upper Portland Beds f Oolitic and shelly limestone and marl with Ostrea expansa J. Sow., Trigonm 3 I Chalky rock, with Ammonites, Lucina portland- ica, Trigonia 4 Brown clay, with Ostrea Oolitic earthy rock ... Yellow sand, dark glauconitic sand and marly beds : Pecten lamel- losus Glauconitic marly limestone, be- coming sandy in lower part : Car- \ 7 or 8 dium dissirmle J. de C. Sow., Perisphinctes giganteus, Trigonia, j Ostrea, Serpula tricarinata? J. de C. Sow. Nests of green sand in | places i Lydite bed : brown clay with pebbles See also A. Morley Davies Proc. OeoL Atsoc., xvi., p. 30. PURBECK BEDS. 61 Lower Port- ( Ft. in land Beds ! Brown and greenish mealy sand 3 6 passing down { Sandy clay, passing down into stiff blue clay, into Kime- j w [th iridescent Ammonites, Thracia, Perna, 20 ridge Clay ^ Astarte hart well exsis. This section agrees in the main points with that recorded by Fitton, 1 who enumerates a number of fossils. The pits were visited by the Geologists' Association under the guidance of Prof. J. F. Blake in 1893, and he then recorded from the fossiliferous glauconitic bed the following fossils 2 : Holcostephanus " biplex." Pecten lamellosus. Perisphinctes bolonieusis. Perna Bouchardi. Cardium Pellati. Pleuromya tellina. Lima rustica. Trigonia muricata. Mytilus boloniensis. Pellati. At the base of the Portland stone-beds on Muswell Hill, as. at Brill, there is a similar glauconitic limestone with Cardiwn dissimile, &c., beneath which copious springs are thrown out at various points around these outliers. PURBECK BEDS. BY G. W. LAMPLUGH. Shotover Hill. There is no evidence of Purbeck Beds on the main portion of Shotover Hill, but in the south-eastern portion of the Portlandian outlier traces of Purbeck Beds were noted here and there by Fitton. 3 Thus above the Portland Stone at Combe Wood, south of Wheatley, he observed beds like the " Malm " of Garsington. They consisted of compact and oolitic limestone and rubble, and yielded remains of Cypris, Mytilus, Modiola, Paludina elongata and Planorbis? They are over- lain by the Shotover Beds. The following section of a stone-pit at Garsington is here abbreviated from that recorded by Fitton 4 : Ft. in. Loamy soil ... 2 [Shotover / Ferruginous brown sand and greenish sand, with Sands] 1 yellow ochre and fuller's earth 8 f Malm, soft limestone, and softer marl, much de- composed ; comprising : a. Light greenish-grey marl with,in the upper part, detached fragments of silicified coniferous wood, like that of Portland, [Purheck Beds] { and portions of bone ; b. Limestone, with some oolitic grains ; Palu- dina, Planorbis ? Mytilus, and Cypris ; c. Limestone, in some places like the I "Pendle" of the pits at Whitchurch, 1 oolitic and botryoidal in places, with ; I Paludina, &c. Portland Stone 1 Trans. Geol. 8oc., ser. 2, iv., pp. 280, 283, 299 ; see also Whitaker, in Geol. Banbury, pp. 47-49 ; J. Mitchell, Proc. Geol. Soc., ii., p. 6. 2 J. F. Blake, Proc. Geol. Axsoc., xiii., p. 73; Quart. Jorn. G -ol. S'>c., xxxvi., pp. 209, 226, &c. ; see also H, B. Woodward, "Jurassic Rocks of Britain," v.. p. 222. 3 Trans. jGeol. Soc., ser. 2, iv., pp. 272, 275. * Ibid,, ser. 2, iv p., 277. 62 UPPER OOLITES. Brtil. The presence of Purbeck Beds beneath the Ironsands of the Brill outlier was first definitely recognised by the Rev. P. B. Brodie, in 1867, l though one of tne sections (C) at Brill, published by Fitton in 1836, 2 includes the strata since found to belong to the Purbeck series. Phillips, 3 in 1871, gave the following generalized section of the series : Ft. in. White calcareous laminated band, marly and stony 1 Grey argillaceous beds ............... 3 White calcareous, marly or stony [bed] ... ... 2 Grey clay ............ ......... 6 White laminated stone ... ... ... ... ... 1 Grey clay ..................... 1 White stone .................. 1 Grey clay ...... ............... 6 10 It is possible, however, that the thickness is here over- estimated, as the sections on the lower slope of Brill Common, in which these beds are exposed, are much obscured by slips, which tend to duplicate the strata. The present exposures seem to indicate a total thickness of not more than five or six feet; but as the series is evidently very variable both in composition and thickness, it may have been locally thicker in the excavated part of the Common than in the places where it still remains. The best exposure when the ground was surveyed (in 1904) was in a small stone-pit, close to the west side of the high road that runs along the eastern margin of Brill Common, 300 yards north of Temple Farm. The beds were much slipped, and were also disturbed by previous workings, but the section appeared to be as follows 4 : Ft. in Top soil, &c .......... ............ 1 Oto2 Pale grey clay, with a pimply structure suggestive of ostra- coda, and with bits of plants : much slickensided and & i brecciated by slipping ... ... ... ... ... about 1 g J White and buff fine sand and pale grey clay, with crushed remnants of ironstone concretions : irregularly mixed and confused ..................... 3 to 4 ^ I Yellow and pale buff fine sand and sand-rock with ironstone m I concretions at base .................. 1 w ( Tough bright-green clay with rusty spots, with some earthy fragments and ironstone concretions : much crushed : called " peter " by the quarry men ......... 6 to 9 "o -{ Brecciated white stone and marl, with broken lumps of j | hard calcareous grit (" pitching-stone " of the quarrymen) a | at the top, and Portland limestone below : all crushed and ^ L mixed by slipping ....... .. ... seen for 3 The quarrymen state that the " pitching-stone " (which is dug for road- metal) occurs in two irregular beds, 4 with a parting cf sandy loam 1 Quart. Journ. Geol. Soc., vol. xxiii., pp. 197-199. 2 Trans. Geol. Soc., ser. 2, vol. iv., pp. 280-281. 3 Geology of Oxford, &c., p. 418. 4 Compare Fitton's section, op. cit., p. 281, f PURBECK BEDS. 63 between, the lower and thicker bed averaging 6 inches in thickness. From the heap of this " pitching-stone " at the entrance to the quarry some oh- scure and indeterminable fossils were obtained, apparently fragments of marine lamellibranchs. Traces of the bright- green clay that is regarded as the topmost bed of the Purbeck in the above section, were also visible in the tieep sand-pit at the more northerly windmill on Brill Common ; and there appears to be a trace of the lower part of the series at the top of the quarry in Portland limestone, 80 yards distant, at the northern edge of the Common. In an old pit, 450 yards further south, on the slope below the Congre- gational Chapel, a much-obscured section revealed Purbeck Beds of a different type, consisting of 3 or 4 inches of tough black earth or clay, suggestive of an ancient surface-soil, resting on 4 to 6 inches of tough dark- grey earthy material speckled with small bits of a paler material like decomposed white stone. A peculiar earthy breccia of similar character to the latter bed, but much thicker and coarser, forms part of the Purbeck Beds exposed in the well-known " Bugle" Pit at Hartwell 1 ; and similar material has also been recently exposed in a railway-cutting on the Great Central line, mile west of Haddenham. In the Brill section, thin shell- fragments were abundant both in the earthy breccia and in the tough black clay above it, but were not sufficiently well-preserved for identification. It is only in the above-described sections of Brill Common that the Purbeck Beds are traceable, and they are consequently indicated on the map only in this quarter. Traces of greenish clay above the Portland Stone were observed by Mr. Wood- ward to the east of Brill Church, on the scarp below Hampden House. Whether the series is prolonged northward into the Muswell Hill outlier, and southward beyond Brill, is very doubtful; for although beds so thin might be readily hidden by downwash on the steep slopes in which their outcrop would occur, it is just as probable, from their general structure, that they were originally impersistent, and, moreover, that they have been partly cut away by the stronger current that depo- sited the Ironsands. The fossils indicate that the series is of estuarine origin, marking the transition from the purely marine conditions of Portlandian times to the fresh-water conditions indicated by the Ironsands (Shotover Sands). 1 [This rubbly bed at Hartwell |* appeared to me to belong to the Drift " when I examined the section prior to the publication of the Memoir on Jurassic- Rocks (see vol. v., pp. 224, 279). The bed was then exposed only at the surface ; it has since been cut back so as to expose higher beds of Purbeck strata above it, and its position in that formation is no longer to be doubted. H. B. W.] 64 LOWER CRETACEOUS. CHAPTEE VII. LOWER CRETACEOUS. BY G. W. LAMPLUGH. SHOTOVER SANDS. The Brill and Muswell Hill Outliers* The Upper Jurassic rocks in the extreme north-eastern corner of the area, are capped by two isolated patches or out- liers of sand, with subordinate bands of clay, to which the general term of " Ironsands " has been usually applied on account of the prevalence of ferruginous material in some of the beds. From the conspicuous development of the same series on Shotover Hill near Oxford we have entitled these deposits, " the Shotover Sands." These Ironsands form the tops of prominent hills, which rise boldly to a height of 100 to 150 feet above the surrounding plain of the Upper Jurassic clays, and are evidently the relics of an originally extensive deposit, of which the greater part has been removed by denudation. On Muswell Hill, the most northerly of the outliers, the Ironsands occupy an irregularly oval area having an extreme length of 1,400 yards and an average breadth of about 500 yards. On the south- east, this tract extends to within 500 yards of the north- western edge of the Brill outlier, being separated from it only by a shallow gap of erosion in which the Kimeridge Clay is exposed. The picturesque little town of Brill stands on the well-marked plateau formed by the Ironsands of the second outlier, which owes its level summit to the cementation of the sands into tabular concretions of ferruginous grit in the uppermost remaining beds of the group. This little plateau is deeply indented on all sides by short steep-sided combes or valleys, excavated by the springs which well out from the Ironsands or from the underlying pervious Portlandian strata resting upon the Kimeridge Clay. 1 The outlier is elongated in the same direction as that of Muswell Hill, from N.W. to S.E., and is close upon one mile in its greatest length. Although, owing to the prevalence of current-bedding and lenticular stratification, it is not possible to determine the dip from particular exposures, a gentle inclination of the Ironsands towards S.S.E.. is brought out by the mapping, the base of the group falling from the 600-feet contour-line at the northern end of the Muswell Hill outlier, to the 500-feet line at the southern end of the Brill outlier. The underlying Portlandian Beds show a corresponding inclination, so that the uncon- formity between the two series, deducible from wider evidence, is not apparent in this district. The Ironsands appear also to lie in a very slight trough, of which the axis runs centrally to the major direction of the outliers; but owing to the downwash of the sands on the steep rising ground this structure cannot be demonstrated 1 [Including here the Hartwell Clay. H.B.W.] SHOTOVER SANDS. 65 with certainty. If present, it may be due either to a gentle synclinal flexure of the strata, or to a slight hollow of erosion formed previously to their deposition. In composition, the Ironsands show much local variation, while maintaining their general characters with a fair degree of constancy. This is very well seen in the numerous excavations on Brill Common which occupies the steep northerly slope of the Brill outlier, where the sands have been dug for building and other purposes, and the clays and silts for making bricks and tiles. Only a small portion of the group is seen in any particular section ; but as the excavations range from top to bottom of the hill, almost the whole sequence is exposed here, though the lowermost portion is confused by slipping. By combining this evidence, the following 1 generalized section of the Brill Ironsands in downward succession has been obtained : GENERAL SECTION OF THE IRONSANDS ON BRILL COMMON. Description. Where best seen. Average thickness. Top soil, brown sandy loam full of 1 to 3 ft. of fragments of ironstone 1. Loamy ferruginous sand and sand- Sand-pit in field 5ft. rock, with tabular concretions of at crest of hill ironstone, and much streaked with 200 yds. N.W. of smooth whitish clay Brill Police Station 2. Fine buff or white sand, with ferru- ^) ginous bands and incipient iron- | Same locality ; 10ft. stone concretions, and a few clayey and lower part streaks, passing down into [ in sand-pit 25 3. Ashy grey and brown fine loamy yds. S. of Mill 5ft. sand, silt and grey silty clay, with Cottage, Brill traces of plants J Common 4. Very fine sharp white sand with filmy Ditto 4 ft. streaks of clay 5. Shaly brown and lavender clay and Clay-pit east of 4ft. loam, with traces of plants Mill Cottage 6. Fine white or ashy-grey sand and Sand-pit at the 10ft. sand-rock, with thin laminae of clay northern Wind- and some hollow ironstone con- mill, and another cretions pit 20 yds. S. of the southern Windmill 7. Ochreous clay, with concretionary Ditto 4 in. to 6 in. ironstone showing obscure traces of fossil shells and plants 8. Ashy grey, lavender and brownish Ditto 5ft.+ loam with layers of sand, showing traces of plants Base not well seen, resting on Purbeck Beds (see p. 62) in the stone-pit adjoining high road, at east side of Common, 300 yds. N. of Temple Farm ; and in old clay (?) pit on west side of Common (see pp 62-3.) Total thickness, about 45 ft, 9813 F 66 LOWER CRETACEOUS. With the exception of indeterminable fragments of plants, fossils are very rare in these deposits, but there is clear evidence that the beds have been laid down in fresh water. From an ironstone band at Brill, the llev. P. B. Brodie obtained u a small Paludina, coarsely but strongly ribbed, and apparently distinct from any figured and described by Professor Phillips" [from Shotover]. 1 The only shells found at Brill during our survey were the obscure indeterminable casts in ironstone mentioned in the above section ; but blocks of similar ironstone, found rather abundantly at about the same horizon in the banks of the road and the adjacent ploughed fields on the south-eastern slope of Muswell Hill, within half a mile of Brill Common, were frequently crowded with recognisable casts of Cyrena media, J. de C. Sow., and in one instance with Unio porrectus, J. de C. Sow. 2 Fitton, 3 in his account of the Brill sections, describes the occurrence, in a clayey bed (probably No. 5 of the above section), of an entire tree, converted into pyritous lignite, full 40 feet long, the trunk about a foot in diameter, with branches that extended to about 10 feet beyond it on both sides. The position of the clay-pit from which this tree was obtained is given as " about 20 feet below the road on the south-west [ ?] of Brill." Besides the direct evidence afforded by these fossils, there is the further fact that the more fossiliferous Ironsands of Shot- over, which clearly belong to the same series, as will presently be shown, contain only fresh-water fossils. The occurrence of the thin band of Purbeck Beds at the base of the Iron- sands of Brill, as already described, has an important bearing upon the question of the age of the latter series. These Purbeck Beds plainly indicate the change from the purely marine conditions of the underlying Portlandian deposits to the brackish water and variable conditions following upon a recession of the sea ; and in the Ironsands we have indica- tions of the succeeding stage, when the district rose entirely above sea-level and the only deposits were those of fresh- water origin. This stage presumably followed directly upon the estuarine episode ; and the deposits are therefore only slightly newer than the Purbeck, i.e., they represent the lowermost part of the Wealden series of Kent and Sussex, and may be roughly correlated with the Hastings Beds, but are probably older than the Weald Clay. The fresh-water fossils are, unfortunately, so few in species, and these so little known, that the evidence for this correlation must rest mainly upon the stratigraphical relations of the Ironsands. The belt of silty clay which occurs in the section on Brill Common gives rise to small springs in this locality; but the main outflow of water, both from the Brill and from the Muswell Hill outlier, comes from the Portland Beds, show- 1 Quart. Journ. Geol. Soc., vol. xxiii. (1867), p. 198. 2 An example of Unio was also obtained in 1893 during an excursion of the Geologists' Association. Proc. Geol. Assoc., xiii., p. 73. 3 Trans. Geol. Soc., ser. 2, vol. iv. (1836). p. 280. SHOTOVER SANDS. 07 ing that neither the clays associated with the Ironsands, nor those of the underlying Purbeck, are' sufficiently persistent to arrest the percolation of water downward into the Port- landian strata. At the same time it is noteworthy that the Ironsands of Shotover also include a clayey zone which occurs in approximately the same position as at Brill (see p. G9). Like most river-deposits, the varied sediments tend to arrange themselves in elongated lenticles, and not in regular layers like the sediments of deeper and quieter waters. On Muswell Hill the Ironsands are scantily exposed, the only sections being the much overgrown road-cuttings at the eastern and western ends of the hill, and the small sand-pits at the two farmsteads on its south-western flank. Streaks of damp clayey soil occur in relatively the same position as at Brill, and the generalized Brill section given above is probably representative for the Muswell Hill outlier also. No indication of the presence of Purbeck Beds between the Ironsands and the Portlandian strata was, however, observed in this outlier. Shotover Hill. Shotover Hill, 2| miles east of Oxford, owes its prominence to a thick capping of more or less ferruginous sand, with some interbedded clay-beds, and much concretionary iron- stone, the latter being especially abundant in the upper part of the series. These beds form the flat crest of the long narrow ridge which extends E.S.E. for over 1J miles nearly to Wheatley. South of Littleworth the Ironsands are cut out for 300 yards or so by a depression in the ridge, but they reappear in the rise of the ground beyond this space, and are then prolonged in another ridge which sweeps round southward from Wheatley for about two miles, nearly to Grarsington. These ridges form two separate outliers of the Ironsands, surrounded by the Portlandian Beds which occupy their slopes, while a third outlier is formed by a small patch of the ironstones and sands which occupy the summit of Red Hill, one mile north of Wheatley. The springs which burst out around the margin of the two larger outliers, where the pervious Ironsands and Portland Sands rest upon the Kimeridge Clay, have deeply indented the ridges, thereby giving an irregularly lobate outline to their borders. The ferruginous sands of Shotover, along with those of the similar outliers at Brill, lying six miles to north-eastward, were originally considered as forming part of the marine Lower Greensand Series. The discovery by the Rev. H. Jelly, of Bath, that fresh-water shells belonging to the genus P4 N\V - DRIKFIELD By J. R. SB - - KEXDAL. By W . T. A v KLINE and T. Me K. HUGHES. 2nd Ed. by A. . - APPLES Y, ITLLSWATER, &c. By J. R. DAKYNS, R. H. TLDDEMAN, and J. G. GOODOHILD. 1*. 6d. - NORTH CLEVELAND. By G. BARROW. Is. 6d. - CARLISLE. By T. V. HOLMES. 1*. M. - OTTERBURN and ELSDON. By HUGH MILLER. 25. Qd. - CHEVIOT HILLS. By C. T. CLOUGH. Is.Qd. - PL ASH ETTS and KI ELDER. By C. T. CLOUGH. 1?. - WOOLER and COLDSTKEAM. By W. GuNN and C. T. CLOUGH. 1*. M. - NOR H AM and TWEED MOUTH. By W. GuNN. 6d. - COAST SOUTH of BERWICK-ON-TWEED. By W. GUNN. Qd. - BELFORD, HOLY ID, and FARNE ISLANDS. By W. GUNN, 2s. Gd. SHEET MEMOIRS OF NEW S1EIES MAPS. 110 - - - MA.CCT.E9FIELD, CONGLETON, &c. By T. I. POCOCK [and Others]. 2a. 6d. }:% . STOKK-UPON -TRENT. By W. GIBSON and C. B. WEDD. (Jnd Bd.) Price Is. Qd. - DERBY, BURTON-ON-TRE NT, Ac. By C. FOX-STRA NOWAYS. Zs. 155 . . - ATHERSTONE and CHARNWUOD FOREST. By C. FOX-STRANGWAYS. 2*. 156 . . -LEICESTER. By C. Fox-STRANGWAYS. 3-s. 230 - - - AMMANFORD. By A. STRAHAN [and others]. 2. 6(1. In - MERTHYR TYDFIL. By A. STBAHAN, W. GIBSON, and T. C. c ANTHILL, is. 6d. V3? . . - ABERGAVENNY. By A. STRAHAN and W. GIBSON. 25. 24 . - - WEST GOWER, By A. STRAHAN. 8