A HISTORY OF BERKSHIRE Hill, a mile off Reading ; in digging there they find first a red gravel, clay, chalk, flints, and then a bed of huge petrified oysters 5 yards thick 20 foot below the surface ; these shells are full of sea sand.' Above the bottom bed at Reading are some sandy beds which occur in a very irregular manner and occasionally contain layers of clay with abundant and very perfect impressions of leaves of plants. This leaf bed has also been found in the brickfields at Knowl Hill between Twyford and Maidenhead l and at Shaw Hill near Newbury. The oyster bed shows that this formation was deposited in salt or at any rate brackish water, and the leaf beds that land was not far away ; probably Berkshire was at the time in the seaward part of the estuary of a great river. Mr. J. Starkie Gardner has remarked that the plants are of a remarkably temperate aspect, the leaves and fruits of the plane tree for instance being conspicuous. 2 In some places these sands contain numerous clay galls of large size, some as much as 18 inches in diameter. Some are mottled, but the majority are grey in colour. Many are ferruginous and somewhat sep- tarian, and ferruginous nodules also are found. 8 Above the sand there is usually some 40 to 50 feet of mottled clay without fossils and above it are sometimes more sands, but the whole of the Reading Beds are irregular and no two sections are alike. They are worked for bricks, tiles and coarse pottery at many places. There is a record of an unsuccessful attempt to obtain coal at Hose Hill in the parish of Burghfield on the south bank of the Kennet valley about 4! miles south-west of Reading. 4 It was probably through alluvium and Reading Beds. LONDON CLAY The Reading Beds are overlain by the London Clay ; its basement bed, some 10 feet thick, consists of green-coloured sands and clay with bands of calcareous stone and some pebbles. It usually contains one or more lines of fossils, and in one case, Mock Beggars Brickfield on the east of Reading, it was found to be fossiliferous throughout. The shells are of marine species ; Pectuncu/us and Cardium are very common at Reading. The two valves are frequently united and the shells show no sign of rolling, so that they no doubt lived on the spot. The annelid Ditrupa plana is very abundant. In the Winkfield boring this basement bed was 6 feet thick and consisted of green-coloured sand with shells. Its stony beds, with the characteristic Ditrupa, may be seen in the Bray cut. It was 10 feet thick in the Wokingham well, and has been exposed in the railway cutting at Sonning and in many brickfields near Reading, Newbury and other places ; in short it is very persistent throughout the county. It is a water-bearing bed, but only furnishes small supplies. 1 H. J. O. White, Pnc. Geol. Assoc. (1901), xvii. 181. 8 The British Eocene flora (Palaeontographical Society), ii. I. ' T. R. Jones and C. C. King, Quart. Journ. Geol. Soc. (1875), ***' 453-
- J. Rofe, Trans. Geol. Soc. ser. 2, v. 129 (1837).
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