374 



THE LOWER-LEVEL GRAVEL-BEDS. 



thickness of three hundred feet. The greatest development of 

 it which I have seen in the north of France was in a pit in 

 the Hue de la Chevalerie, near Ivry, where it was twenty-two 

 feet thick ; some of this, however, may have been reconstructed 

 loess brought down by rain from the higher ground in the 

 immediate neighbourhood. Assuming that this loess is com- 

 posed of fine particles deposited from standing or slowly- 

 moving waters, we might be disposed to wonder at not finding 

 in it any traces of vegetable remains. We know, however, 

 from the arrangement of the nails and hasps, that in some of 

 the St. Acheul tombs wooden coffins were used, while the size 

 of the nails shows that the planks must have been tolerably 

 thick ; yet every trace of wood has been removed, and not even 

 a stain is left to indicate its presence. We need not, there- 

 fore, wonder at the absence of vegetable remains in the drift. 



Such is a general account of those gravel-pits which lie at 

 a height of from eighty to one hundred and fifty feet above 

 the present water-level of the valleys, and which along the 

 Somme are found in some places even at a height of two hun- 

 dred feet. 



Mr. Prestwich gives the following table of the mammalia : 



