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



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

 relative position. They 7iiust 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 neighborhood 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 bui'ied 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 incumbent loam with 

 land shells, or through fine sand with fresh-water mollusks, 

 before we get into the beds of gravel containing hatchets. 

 Occasionally a weapon used as a projectile may have fallen 

 into quiet water, or may have dropj^ed from a canoe to the 

 bottom of the river, or may have been floated by ice, as are 

 some stones occasionally by tlie 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 Society Koy. d'Emulation d'A.bbe¥ille>.1834, p. 197. 



