136 X. H. WINX'HKLL WAS MAN IN AMERICA IN GLACIAL PERIOD 



the fingers of the two hands. What must therefore be the number of 

 3^ears required for the rotting and the canA^oning of the Tertiary gran- 

 ites of Colorado ? We may safely say they are one hundred times as 

 many as the 3^ears of post-Glacial time. 



That man was a denizen in North America during this long period or 

 any portion of it there is no affirmative evidence; but that the physical 

 conditions of the continent would not necessarily have excluded him, 

 and, on the other hand, were quite favorable for his habitation, there is 

 reason to believe. 



Pre-Glacial Geest Covering 



By the term Glacial period is meant the whole time involved in the 

 production of the drift deposits in their present attitudes. It is not nec- 

 essary to inquire into the relative importance of the periods of warm 

 and cold climates with which the Glacial period was diversified or 

 whether they shall be called phases or epochs. The thickly geest-cov- 

 ered surface suffered a profound erosion. It is but a trite remark to say 

 that the drift deposits are derived from the rocks of the country ; but it 

 should also be remembered that to a large extent, and perhaps to a 

 larger extent than is commonl}'' estimated, that derivation was second- 

 ar}^ rather than direct. Long exposure had superficially rotted the 

 rocks, as already remarked, to a considerable degree, and this rotted 

 material supplied the first contribution to the drift deposits. It seems 

 but a reasonable inference that this thick geest la3^er was first disrupted 

 and transported from the northern latitudes, and that in those latitudes 

 in which glaciation waned and finally ceased there w^as little or none of 

 that disturbance. Between these extremes all degrees of preservation 

 of the geest la3''er is still to be seen. I do not mean that the geest layer 

 is usually intact within the glaciated latitudes, but that in going toward 

 the south one finds more and more of the direct elements of that rotted 

 material, mingled with the local drift deposits, and less and less of the 

 far-transported material. Finall3^, the drift deposits cease as transported 

 material, and there is a visible and now w^ell known slow horizontal 

 transition into the loess of the region, in which there is traceable little 

 or no sign of glacial action. If a short consideration be given to the 

 variation and the geographic distribution of the geest, it will be found 

 to display several interesting and important features : 



1. The uppermost portions of the stratum, involving a thickness vary- 

 ing from zero to several feet, may be so completely leached that it has 

 the nature of a residuary clay, but below that depth more or less of the 

 alkaline earths remain. Owing to the universality of capillary attrac- 

 tion, by which the deeper ground waters are drawn to the surface w^her- 



