026 GEOLOGY 



and when the adjacent country was filled with game and when the 

 glacial gravels were exposed in bluffs and channels, these streams 

 must have afforded abundant material for stone implements. 



The demonstration of two stages in the manufacture of arrow- 

 points, spear-heads, knives, etc., as practiced by the aborigines of 

 the country, raised the question whether there are any true paleo- 

 lithic artefacs in North America. The difficulties of discriminating 

 between "paleoliths" and " rejects," if indeed they can be discrim- 

 inated, is illustrated by Fig. 604. One of the chipped blades 

 represented has been regarded as a typical "paleolith, " while the 

 other forms are "rejects." 



It has been found that most of the artefacs in valley gravels 

 are in their superficial portions, in their talus slopes, or in secondary 

 deposits, many of which are of recent origin. Of the less superficial 

 finds, many have been shown to be cases of relatively recent burial 

 by natural means. The processes of streams in cutting down their 

 channels in valley gravels are such that superficial material may 

 be buried to very considerable depths. In their meanderings, they 

 cut into the bordering terraces or uplands, developing steep bluffs. 

 When the meanders shift, as they are sure to do, the bluffs grade 

 down to a slope by the falling, or sliding, or washing of the top to 

 the bottom, as illustrated in Figs. 605-607. The material which 

 was in the top originally, may get into the base of the talus, and be 

 buried deeply. Similar secondary burial takes place in all sorts 

 of loose material of eolian, pluvial, and fluvial origin. It is to be 

 noted that this is a normal process, not an exceptional one. There 

 are other ways, too, notably scour and fill (p. 184), in which human 

 relics may be buried in river gravels. 



Without further details, it may be said that human relics have 

 not been found, in America, in gravels known to have been deposited 

 in the glacial period, or before. All that have been reported from 

 glacial gravels, have been found either in such positions as to slum* 

 that they were buried in post-glacial time, or in such position 

 to make this inference tenable. The existence of man in America 

 in the glacial period or before is therefore not demonstrated. 



Sources of good evidence. There are two classes of formations 

 in which good evidences of glacial man, if there was such man in 



