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 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. 10