A HISTORY OF BERKSHIRE the county, which is surrounded by Chalk, and is known as the Shal- bourne Inlier. It consists of greyish and yellowish-brown sand with green grains (glauconite) and with beds of irregular blocks of hard grit. It is, according to Mr. J. H. Blake, probably over 45 feet thick. In east Berkshire the boring at New Lodge, Winkfield, reached the Upper Greensand at a depth of 939 feet, or 721 feet below the sea level. The thickness of the formation was 295 feet, much the same as in the west, and probably it passes under the whole of Berkshire east of its outcrop. CHALK The Chalk occupies a large part of the surface of Berkshire, and in the eastern part of the county when not at the surface it is to be found underground. It is a porous formation, and the rainfall on the large area at the surface collects and furnishes a water supply throughout nearly its whole extent. In the east earth movements have folded the Chalk into a basin shape, the middle of which is filled with clay and sand beds of Eocene age. The south side of this basin lies in Hampshire, and there the dip is steeper than on the north side, a fact of much importance from the well sinker's point of view. The Chalk was found at a depth of 603 feet at Wellington College, and at 490^ feet at Ascot Racecourse. At Wokingham the depth to the Chalk was found to be 344 feet, at Bearwood 350 feet, at Burghfield Hill 280 feet, and at St. Mary's College, Woolhampton, 2781 feet. The solid bottom of the Thames valley below the alluvium and gravel is Chalk for the whole distance from Wallingford to Bray and also at Windsor, where the Chalk is bent into an anticline. The Kennet valley is cut in Chalk from the county boundary to Newbury and from Theale to the Thames. The Lodden flows over Chalk for the last three miles of its course only. In Reading the Abbey Ward is on Chalk, and so is the whole of the Oxford road and most of the area between the river Kennet and the London road. The Chalk in the town as in many other places is nearly concealed by coverings of gravel, alluvium, etc., and wells and other sections show that it is often 1 5 feet, 20 feet, or even more below the surface of the ground. One well passed through 28 feet of drift before reaching the Chalk. In central Berkshire the Chalk is much covered by a formation known as clay with flints, the result of its dissolution by surface water, as will be explained later on. The Chalk is a light coloured limestone, sometimes soft and earthy but often very hard. Its total thickness at Winkfield was found to be 725 feet. It is divided into three divisions : 1. The Lower Chalk, about 215 feet thick. 2. The Middle Chalk with the Melbourn rock at its base, about 170 feet. 12
