MAN AND THE GLACIAL PERIOD. 675 



Abundance at the base of the deposit of " black soil" which 

 overlies the gravel to an average depth of about one foot. 

 ;i The flint implements known as Indian relics belong to this 

 superficial or black soil," and they are found abundantly on 

 the surface, more sparingly near the surface, and u more 

 sparingly still the deeper we go," until, on reaching the 

 gravel proper, they disappear entirely. 



In this connection it is interesting to note that at the 

 mouth of Kaaman's Creek, the nearest point on the river from 

 the shelter-cave just described, Mr. Cresson has also discovered 

 remains of prehistoric wooden structures below the level of 

 low tide. These consist of the ends of rude piles which had 

 evidently been fashioned by stone implements, but for what 

 purpose intended it is not evident. In dredging here, he 

 found numerous rude argillite implements of the palaeolithic 

 type, which, in the vicinity of two of the structures, were 

 mingled with those of a modern type. 



Thus the valley of the Delaware would seem to contain 

 a record of the passage of the race on the Atlantic coast 

 from the Palaeolithic to the jSTeolithic age. Here, about as 

 far below the ice-front at that time as the shore of Greenland 

 now is, the hardy hunters who had been driven before the 

 advancing cold of the great Ice age found ample space for 

 their pursuits, and excellent shelter in the dense forests which 

 everywhere bordered the southern front of the great snow- 

 tields. The proximity of the ocean furnished, doubtless, a 

 supply of fish, while numerous animals, long since extinct in 

 this region, were for a time fellow-fugitives with man from 

 the advancing northern foe. Among these companions of 

 man we may pretty certainly include the mastodon (one of 

 whose tusks, as already remarked, was found by Professor 

 Cook in the Trenton gravel itself), the walrus, the Greenland 

 reindeer, the caribou, the bison, the moose, and the musk-ox, 

 for the remains of all these animals are found either in the 

 superficial gravel deposits of southern Xew Jersey, or in the 

 adjoining region of country to the south and west. The 

 picture of human life during that period in the valley of the 



