Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/292

 entire thickness of some of the pits is made up of the same sands and clays as on the opposite side, but more uniformly disseminated through the whole mass, forming a kind of loam more like No. 12 than any of the other beds that have been there described; ochreous concretions and pyritical nodules abound in it as in No. 12. The total thickness of this deposition at David's Hill above the chalk is about 40 feet. Water occurs in the subjacent chalk, as soon as they sink 30 feet into it. It is separated from the incumbent brick earth by the bed of green sand, with the same oysters as at Catsgrove.

The whole of these beds above the chalk at Reading (those at Catsgrove as well as at David's Hill) appear to be subordinate parts of one formation, the next in order of succession above the chalk, older than the London clay and calcaire grossier of Paris, and contemporaneous with the lowest strata of the plastic clay formation nearest the chalk, the general history of which we propose more fully to consider.

On the north side of the town of Reading these strata do not occur, being cut off by the great valley through which the Thames passes, and which has been excavated to a considerable depth in the subjacent chalk. But they occupy much of the ground between Reading and Newbury, and are seen at Hermitage, on the N.E. of Newbury towards Hamstead Norris, whence a range of low hills composed of them stretches eastwards towards Reading, and westward to Boxford, Wickham, and the neighbourhood of Hungerford, interrupted by vallies, which are often cut down into the subjacent chalk.

The breadth of this deposition on the north and south of Newbury, is from Beedon Hill six miles north on the road to Market Ilsley, to Whitway near Highclere four miles south of