London road about two miles east of Beaconsfield. These with other extensive beds of the same era which occur between Bulstrode and Windsor, are in almost immediate contact above the chalk, and appear to belong to the formation of plastic clay. The Windsor fire bricks and soft sandy bricks for arches, are probably also made from beds of this same formation. Mr. Warburton has been told that at Clewer near Windsor, the Thames cuts through a bed of shells which he suspects to be the same as are found at Woolwich.
We will now leave the beds of the plastic clay formation in the London basin, to trace them in the same relative position on the coast of Sussex.
A similar deposition of sand to that of Reading containing a breccia of chalk flints as its lowest stratum, (about three feet thick) was noticed by the Honourable H. G. Bennet and myself in July, 1814, between Newhaven and Beachy Head, in the cliff at Chimting Castle half a mile on the east side of Seaford. The sand here is fawn coloured passing into olive with flakes of mica almost a line in diameter, and occasionally contains irregular veins and masses of tubular concretions of iron-stone. Its greatest thickness is under 50 feet. Mr. Warburton informs me that he has seen similar concretions in the same stratum of sand at Sudbury in Suffolk, in immediate contact above the chalk. Under this sand at Chimting the breccia of the lowest bed forms an ochreous pudding stone composed of sand and chalk flints, (the latter both rolled and angular) the whole being strongly united by a ferruginous cement, and the flints covered externally with a green coating like those in the oyster bed at Reading. Specimens of this breccia have been presented to the Society by the Hon. H. G. Bennet. At Chimting Castle there is but a small insulated portion of these strata immediately incumbent
