A HISTORY OF BERKSHIRE 



Further earth movements took place at the close of the Lower 

 Greensand period, and the sea gradually extended until in Chalk times 

 it stretched far and wide over south Europe. There was however still 

 in all probability a land area to the west, including Cornwall, part of 

 Wales and Ireland. 1 



After the deposition of the newest beds of Chalk now remaining 

 in Berkshire there is a very long break in our geological history, which 

 can however be filled in by a study of the rocks in other parts of 

 England, in Belgium and Denmark. Our next formation, the Reading 

 Beds, records a time when, though sea water flowed over at least the 

 south and east of the county, it was water of a great estuary and not of 

 the open sea. 



The succeeding deposits of Eocene age are more marine in character 

 taken as a whole, but land was never far off, and possibly they may even 

 in a small part be of fluviatile origin. 



During or soon after the close of the Eocene period further great 

 earth movements took place, and as the result of the consequent folding 

 of strata the London and Hampshire Basins were separated from one 

 another and Berkshire eventually emerged from the sea and has remained 

 land until the present day. 



A list of works relating to the geology of Berkshire was compiled 

 by Mr. W. Whitaker, F.R.S., and will be found in the Report of the 

 British Association for 1882, p. 340. This list, as well as the 'Geology 

 of parts of Oxfordshire and Berkshire' (GeoL Survey, 1861) by Messrs. 

 Hull and Whitaker, and the 'Geology of the London Basin' (GeoL Survey, 

 1872) by Mr. Whitaker, have been largely used in the preparation of 

 the present history. 



OXFORD CLAY 



As has been already stated, the Oxford Clay is the oldest geological 

 formation which comes to the surface in Berkshire, and it forms a 

 narrow strip of low-lying land extending from the river Cole to the 

 Thames at the northern end of the county. Buscot, Eaton Hastings and 

 Dencourt stand on it. It is a good deal hidden by Gravel and Alluvium, 

 and is mainly grass land. 



It consists of dark-coloured, often shaly clay, with bands of sep- 

 tarian nodules and sometimes a little clayey limestone. Its thickness 

 has been estimated by Mr. H. B. Woodward at 450 feet, the lower part 

 of which represents the Kellaways Rock of other areas. Carbonaceous 

 matter, selenite and pyrites are common. It is a marine mud, and a 

 large oyster (Grypbaa dilatata), a characteristic fossil, has been recorded 

 from Fyfield Marsh. It is not a water-bearing formation. 



The Oxford Clay dips underground to the east and is covered by 

 newer rocks, the first of which is the Corallian. 



For further details reference should be made to Mr. H. B. Wood- 

 ward's monograph on the 'Jurassic Rocks of Britain' (Geol. Survey, 



1 W. F. Hume, 'The Genesis of the Chalk,' Pnc. Geol. ASM. (1893-4), xiii. 211. 



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