THE RECOGNITION OF PLEISTOCENE FAUNAS * 

 BY OLIVER P. HAY 



The determination of the history of the faunas and floras of a 

 great region like North America in a geological period such as the 

 Pleistocene, during which there were numerous and extreme 

 changes of climate, great variations in elevation and therefore in 

 rates of erosion and redeposition, in cold and heat, in rainfall and 

 drought, in kind and amount of food and shelter, is a most diffi- 

 cult subject. The botanists, of course, have their special troubles, 

 but the student of the Vertebrata labors, perhaps, under greater 

 difficulties. The species which he studies are rarely represented 

 by complete skeletons, most of them by scattered teeth and dis- 

 associated bones. Most of his species lived on land and the indi- 

 vidual animals usually perished without leaving a trace of them- 

 selves. 



As in the case of other geological periods, the unraveling of the 

 history of the living beings of the Pleistocene has had to await a 

 somewhat accurate knowledge of the geology. On account of the 

 fact that in the larger part of the region studied in North America 

 the deposits are usually disconnected and relatively little differenti- 

 ated, while another region has been subjected to glaciation, a 

 perplexing phenomenon, it has been difficult to determine the 

 relations of the formations as regards synchronism and succession. 

 The labors of geologists have made great breaches in the wall that 

 stands between us and complete knowledge, but an enormous amount 

 of work is yet to be done. 



In the first edition of Dana's Manual of Geology, published in 1863, 

 this great author divided the Post-tertiary, equivalent to the term 

 Pleistocene, into two epochs, the Glacial and the Champlain. The 

 latter was followed by the Terrace epoch, " a transition epoch, in 

 the course of which the peculiar Post-tertiary life ends and the Age 

 of Man opens." As to the life of the Post-tertiary Dana says (pp. 

 458-459) : 



The Drift epoch in America has afforded no organic relics except half- 

 fossilized wood. There is as yet no evidence of any quadrupeds until the 

 milder Champlain epoch had set in. 



1 Published by permission of the Carnegie Institution of Washington. 

 SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 59, No. 20 



