320 THE GEOLOGIST. 
the contrary, possesses an open and unobstructed view of some distance 
around, and is then separated, by a slight depression, from the higher hills to 
the southward. The pits are of considerable extent, and have been long 
worked for brick-earth, sand, and gravel. The total thickness of all the beds, 
which-repose upon a very irregular and eroded surface of chalk, varies from 
about twenty to thity feet. The worked flints are found chiefly in the lower 
bed of gravel, more particularly in the lower part of it or near the chalk, where 
also the greater number of bones are found, but this is by no means a general 
rule. A considerable number of teeth and bones are also met with in the 
sand and marl above the gravel. 
Fig. 5.— Section in a pit at St. Acheul, on tlie side nearest the Cagny road. 
Fig. 6.— Section in a pit at St. Acheul, on the side nearest the Cagny road. 
