CHAP. VITT. FLINT IMPLEMENTS, WHY FOUND IN DEEP DEPOSITS. 127 



of a rhinoceros, the bones of which were still in their usual 

 relative position. They must have been joined together by 

 ligaments, and even surrounded by muscles at the time of 

 their interment. The entire skeleton of the same species 

 was lying at a short distance from the spot.' * 



If we suppose that the greater number of the flint imple 

 ments occurring in the neighbourhood of Abbeville and 

 Amiens were brought by river action into their present 

 position, we can at once explain why so large a proportion of 

 them are found at considerable depths from the surface, for 

 they would naturally be buried in gravel and not in fine 

 sediment, or what may be termed ' inundation mud,' such as 

 No. 2 (fig. 16, p. 122), a deposit from tranquil water, or where 

 the stream had not sufficient force or velocity to sweep along 

 chalk flints, whether wrought or unwrought. Hence we 

 have almost always to pass down through a mass of incum 

 bent loam with land shells, or through fine sand with fresh 

 water mollusks, before we get into the beds of gravel con 

 taining hatchets. Occasionally a weapon used as a projectile 

 may have fallen into quiet water, or may have dropped 

 from a canoe to the bottom of the river, or may have been 

 floated by ice, as are some stones occasionally by the Thames 

 in severe winters, and carried over the meadows bordering its 

 banks ; but such cases are exceptional, though helping to 

 explain how isolated flint tools or pebbles and angular stones 

 are now and then to be seen in the midst of the finest loams. 



The endless variety in the sections of the alluvium of the 

 valley of the Somme, may be ascribed to the frequent silting 

 up of the main stream and its tributaries during different 

 stages of the excavation of the valley, probably also during 

 changes in the level of the land. As a rule, when a river 

 attacks and undermines one bank, it throws down gravel and 

 sand on the opposite side of its channel, which is growing 



* Musee Societe Roy. d'Emulation d' Abbeville, 1834, p. 197. 



