Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/185

Rh gradient of 1 in 25 in that part. Only 48 feet in height is shown in fig. 23. The sketch is to natural scale; so that the angles of the escarpment of chalk are not exaggerated.

Fig. 23.—Section in Crayford Pit. Fig. 24 is a view near the curved line E F, of the eroded surface of the chalk (A), with rearranged Thanet sands (B) 4 or 5 feet thick.

Fig. 24.—Section in Crayford Pit.

enclosing large flints from the basement-bed. The deposition of 6 feet of coarse flint-gravel (C), on the bed B, in a hollow of the chalk excavated prior to the gravel-period, is well exposed just where the tramway cuts through it.

The brick-earths above the gravel have been excavated. The brick-earth generally is more valuable than the sand and gravel, and the workmen often leave the lower beds in the state shown in fig. 24