OF WESTERN EUROPE AND THE MEDITERRANEAN COASTS. 
909 
and is the one which has been propelled to the greatest distance. A view of part of 
this fine section* is given in fig. 1. The section, however, varies with every fall of the 
cliff. The partial uprooting of a portion of the beach (c) is a noticeable feature. 
The following diagram will show the successive increments of growth,! supposing 
them to have been regular and defined. 
Fig. 2 .—Diagram to illustrate the mode of formation of the ‘ Head' 
E w 
The dark bands represent coarse debris, and the light, fine rubble and loam, or derived Loess. The 
uppermost bed has lost much of its calcareous matter through filtration of the surface waters. 
Except at Folkestone and Portland, land Mollusca are very scarce in the English 
coast sections. At Sangatte they are numerous in places, though limited to the few 
following species, and to the finer portions of the rubble — 
Helix concinna. Pupa marginata. 
„ pulchella. Avion ater. 
Succinea ohlonga. Limax agrestis. 
On the other hand. Mammalian remains are scarcer than with us. I have found a 
few indeterminable fragments of bone, and M. Robbe had in his collection part of 
the lower jaw of Elephas primigenius. Of paleolithic flint implements, several 
specimens have been found on the shore, and one in situ in the rubble. 
Another point calling for notice is the distance to which the flint rubble spreads 
out into the plain, which extends from the foot of the chalk hills to near Calais 
and Guines. Here, as in the coast-plain between Brighton and Selsea, the calcareous 
portion of the rubble decreases in amount as the drift ranges from its base on the slope 
of the hills to the more distant points to which it has been carried. The chalky 
portion is lost either through solution or broken up by friction and incorporated with 
the loess or brick-earth. In a j)it near Hames I found in the thin beds of ochreous 
flint, gravel, and brick-earth, to which the rubble-drift is there reduced, fragments of 
a tooth of the Mammoth, and a few specimens of Pupa marginata, as in the analogous 
beds at Upchurch, in Kent. 
The dry chalk valleys at the back of Blanc Nez exhibit that phase of this drift, so 
* I have described this section with its land shells in detail in ‘ Quart. Journ. Geol. Soc.,’ vol. 7, 
p. 274,1861, and vol. 21, p. 440, 1865. 
t It is the same in the Brighton Cliff (see ‘ Quart. Journ. Geol. Soc.,’ vol. 48, p. 263). 
