HOLMES] ABORIGINAL AMEBIC AN ANTIQUITIES PART I 73 



Professors C'alvm and Salisbiuy agree with Professor Cliainborlin 

 in his very carefully drawn conclusions. 



A large })roportion of the observations relating to the geological 



anti(|uity of man in America cluster about the clos- 



Signiflcance of ing stagcs of the i>lacial period in the northern 



Terms "Glacial" ^t -x i < j. t • i i i 



and " Postglacial " United otates. It is to be noted that the expressions 

 " glacial," " postglacial," and " close of the glacial 

 period " need to be employed with discrimination. Referring to the 

 American Continent as a wdiole, the glacial period did not close until 

 the main body of the general ice sheet disappeared beyond the arctic 

 shores, and the postglacial period did not begin until the ice sheet 

 had thus disappeared. Eeferring, however, to particular localities 

 or regions, the glacial period ended when the ice abandoned that 

 locality or region and the postglacial began. If the close of the 

 glacial period in ^he Ohio or Delaware valleys, for example, should 

 be placed at 20,000 years ago, it might in the region of the Great 

 Lakes have been 10,000 years ago, and in the Mackenzie Valley and 

 Hudson P)ay region 5,000 years ago, and so on. In employing the 

 expression "close of the glacial jieriod," therefore, its particular geo- 

 gra]ihical application should be made clear. 



If, as some hold, the continent was occupied at the period of the 

 last great southward extension of the ice sheet, the 

 prlbk^iis''' ^^^ inhabitants naturally dwelt in the valleys along the 

 southern border, and traces of their presence should 

 be found there. All the peojiles occupying these valleys in post- 

 glacial times down to the present would likewise leave traces of their 

 presence — traces which would owe their characteristics to the kind 

 of culture, the materials available for the arts, and the particular 

 kind of occupation of the site as f(^r hunting, fishing, war, manufac- 

 ture of implements and utensils, dwelling or burial. The archeolo- 

 gist, no matter when the occupancy began or whether it was broken 

 or continuous, must encounter the very exacting task of arranging 

 chronologically the data — the material evidences available on each 

 site and in each district — and determining their true value. Chrono- 

 logical evidence is to be sought in successive, undisturbed deposits 

 of glacial and postglacial ages, more especially in river and lake 

 terraces and in caverns, but the record is not easily read and the 

 true sequence may be determined only by expert and experienced 

 observers. Various agencies have conspired to complicate and con- 

 fuse the record and to render the reading difficult. The unconsoli- 

 dated deposits of post-Tertiary time conform to no uniform order 

 of succession, as do the systematic geological formations. Torrents, 

 the exact period of which can not be determined, have plowed up 

 the flood-plain deposits of the rivers and intermingled them, even 

 reversing the order of original occurrence. The winds have torn 



