MAX AND THE GLACIAL PERIOD. 



617 



chapters of the present volume prepare the way for readily 

 understanding even a summary statement of the facts already 

 discovered con- 

 necting man 

 with the Gla 

 cial period in 

 North Ameri- 

 ca. We may, 

 therefore, with- 

 out further pre- 

 liminaries, at 

 once address 

 ourselves to the 

 subject, and de- 

 scribe the con- 

 dition sin which 



implements Of ^ig. 158. — Reverse side of the implements shown in the preced- 

 " ing figure. 



human manu- 

 facture have been found in the glacial deposits on this con- 

 tinent. 



At the outset two questions arise in the discussion : 1. 

 "Whether the implements found are really artificial and gen- 

 uine. 2. Whether the deposits in. which they occur really 

 belong to the Glacial period. 



1. That the implements are of human origin is evident 

 from close inspection, and comparison with natural frag- 

 ments. Flint and some other species of stone are specially 

 adapted for the manufacture of implements, because of their 

 hardness, and of the facility with which flakes can be struck 

 from them so as to leave a sharp, cutting edge. Many nat- 

 ural forms of flint can be appropriated as useful tools with- 

 out modification. The action of frost upon a flint nodule, 

 or the accidental falling of a stone upon it, may produce a 

 sharp-edged fragment of convenient size for use. But the 

 proof of human workmanship consists in a series of fractures 

 of such character and so arranged that they irresistibly indi- 

 cate design. One prominent feature of an artificial flake is 



