Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/174

80 the intermediate series of stratified gravels, with the lower beds called Combe rock, a mixture of chalk and flint with yellow clay, have been pitched and washed by pluvial action over the escarpment. These materials, derived from the high ground behind the escarpment, and thrown over it, have not been sufficiently water-washed, nor perhaps even placed within the reach of water flowing sufficiently fast, to remove the angles of the soft chalk fragments; nor has the act of deposition abraded the edges of the flint, which are often splintered before being bedded in the Combe rock.

Fig. 11 is another view of the structure of the Brighton gravel-bed, at a point a little to the west of fig. 10, where the escarpment of the chalk must be very near the face of the cliff. The raised shingle-beach is 6 ft. thick, and falls at 8° south to the sea. The position of the present beach is shown 9 ft. below the ancient one. Dr. Mantell first obtained remains of Elephas, from these deposits, near Sussex Square; but no shells have yet been found in them.

Fig. 12 has been, by mistake, reversed in the drawing, and is a vertical section of the Brighton gravel-beds at a point intermediate between that shown in fig. 10 and Sussex Square. By means of a footpath up the cliff, I was enabled to determine the dip of part of the middle series of gravels (d) to be 25° west. The covering bed and gravel (e) and the raised beach deposited at the bottom (b) appear quite horizontal at that point.

The old beach (b) is about 7 ft. thick, and the chalk boulder-bands (c) interstratified with flints about 9 ft. thick, the cliff being about 63 ft. high.

Fig. 13, on a larger scale, exhibits a front view of the cliff 100 yards east of the Rottingdean landing-place, three miles east of Sussex Square, Brighton. This is near the termination of the Brighton gravel-deposit; and I have drawn it to show the manner in which the gravel reposes in a hollow of the chalk, formed by a stream which reached the sea at Rottingdean in the gravel-period.