Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/172

78 which, according to Dr. Blackmore, are associated with, flint instruments of the Amiens type.

Land and freshwater shells are very abundant. The great shell-bed is near the chalk, lying upon a bed of gravel; and the Pupa-bed touches the lower surface of the covering bed of gravel, e. While the curve of the surface is on the average 3° between A and B, the dip of the lower gravel, b, where it touches the escarpment of the chalk, will probably lie at a very steep angle.

The Pupa-bed, c, a fine loess, is marked by a distinct band of colour; it is about 2 ft. thick, and slopes to the river in a gentle curve. I have marked its dip 16°, then 11°, then 9°. The bed c contains only six species of shells, Helix arbustorum (?), Helix hispida, Zua lubrica, Lymnæa palustris, Valvata piscinalis,Pisidium obtusale, besides the Pupæ in immense abundance. The lower band h contains thirty-one species of terrestrial and fluviatile shells, according to the lists of the late Mr. John Brown and Dr. Blackmore.

The chalk, a, is 30 feet from the surface at A, but in 30 yards it reaches the surface; so that the escarpment in the part not yet opened is known to be at an angle of 30°, sloping towards the river. As is usual, the brick-earth is thickest a little way from the escarpment, and passes, on the same horizon, into gravel and sand as you approach the river.

The remains of another arctic mammal (the Musk-Ox) have been recently found in the loess at Salisbury. This animal is now living in a remote part of North America. The stratification at Salisbury, shown in fig. 9, is very similar to that at Erith, fig. 17.

The mammalian gravel and Combe rock extends from Brighton, without interruption, to the point drawn, fig. 10, and presents a cliff of roughly stratified beds facing the sea, about 60 ft. in height. The escarpment of the chalk is known to be not far distant in the rear of the present face of the cliffs at any point; and an extensive fall of gravel has exposed the escarpment of chalk. In the steepest