THE PLEISTOCENE OR GLACIAL PERIOD 925 



while the completed implements were liable to be found only about 

 the dwelling sites, or wherever, in the course of their use, they were 

 lost or thrown aside. In the light of this definite separation, it is 

 not difficult to see how the idea of two stages of art might arise, 

 and how easily the finds might be misinterpreted. 



The' most available sites for finding suitable raw material in a 

 convenient form were the river gravels and the terrace formations. 

 This was especially true in and about the glaciated regions where 



Fig. 603. A series of forms illustrating progressive steps in the manufacture 

 of arrow-points from quartz pebbles obtained mainly from shops and 

 village-sites, near Anacostia, D. C. (Holmes.) 



trains of glacial gravels led away from the ice-fields. In these, 

 quartz, flint, chert, etc., were usually abundant, in the convenient 

 form of pebbles and cobbles. 



The rude artefacs in question have been found chiefly in such 

 gravels, but gravels derived from chert-bearing limestone or quartz- 

 bearing rock are also fruitful sources. In other words, there is a 

 correspondence between the distribution of the ruder artefacs, and 

 that of the raw material. The distribution of the finished artefacs 

 is much wider and more varied. There is special infelicity in sup- 

 posing that great numbers of implements would be lost in glacial 

 rivers during the glacial epochs, for the waters of these rivers must 

 have been so cold and silty, that they contained little life. Later, 

 when the climate was milder and the streams warmer and clearer, 



