A HISTORY OF BERKSHIRE 



importance, for very similar beds at Shotover Hill in Oxfordshire con- 

 tain fossils of freshwater origin. 



The patches of Lower Greensand near Cumnor consist of pebbly 

 sand and ironstone. Mr. Whitaker notes that at Broom Hill these beds 

 fill in and cover the eroded surface of the Kimeridge Clay. 1 



The Lower Greensand is absent under Wantage, for a boring passed 

 from the Gault directly into the Kimeridge Clay. This shows that the 

 patchy character of the formation is largely due to erosion at an early 

 period, before the next bed, the Gault, was deposited. 



At Shillingford the thickness was 25 feet, and the water obtained 

 from it was saline, containing 98 grains per gallon, 54 of which was 

 chloride of sodium. 8 



The Lower Greensand has been found in a boring in east Berk- 

 shire, so that it probably occurs in patches large or small under much of 

 the county. 



The boring was at New Lodge in the parish of Winkfield rather 

 more than 3! miles west-south-west of Windsor Castle. 3 The Lower 

 Greensand was reached at a depth of 1,234 feet (or 1,016 feet below the 

 sea), and consisted of fine sharp light brown sand and contained water. 

 It was penetrated to a depth of 9 feet only. The supply of water was 

 good and it rose to a height of 7 feet 8 inches above the level of the 

 ground. It was found to be remarkably pure so far as regards organic 

 matter, but it contains a large quantity of common salt. This, Dr. B. 

 Dyer, who made the analysis, remarks, is of course not prejudicial to 

 health, though persons of delicate palate might detect a faint trace of 

 salt. The hardness is only 3, so that for laundry purposes the water 

 would be economical. It would be excellent for boiler purposes in the 

 sense that it would not form a crust, though a steam boiler would want 

 occasional blowing out owing to the concentration of salt. 



GAULT AND UPPER GREENSAND 



The Gault and Upper Greensand have been grouped together by 

 Mr. Jukes-Browne under the name Selbornian, 4 and as they are very 

 intimately related to one another they may well be taken together. 

 There was, as has been explained above, a great unconformity between 

 the Lower Greensand and the Oolitic rocks which underlie it, and there 

 is again evidence of a break in the continuity of deposition between 

 the Lower Greensand and the Gault, for the latter overlaps the former 

 in many places and rests directly upon older formations. This overlap 

 is not so noticeable in Berkshire as in other districts, but one instance of 

 Gault resting on Kimeridge Clay has been already mentioned as occur- 

 ring at Wantage. 



The Selbornian crosses Berkshire in a nearly east and west direction 

 from Wallingford to Ashbury, and together with the Kimeridge Clay 



i W. Whitaker, 'Geology of Parts of Oxfordshire and Berkshire,' Geol. Survey (1861), p. 15. 



H. B. Woodward, 'Jurassic Rocks of Britain,' Geol. Survey, v. 127. 

 3 W. Whitaker and A. J. Jukes-Browne, Quart. Journ. Geol. Sx. (1894), 1. 496. 

 ' See A. J. Jukes-Browne, 'The Cretaceous Rocks of Britain,' Geol. Survey (1900), i. 



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