CORRELATION OF THE CENOZOIC 263 



Upper. — The Upper Pliocene, or Sicilian, stage of Europe, typified 

 by the Val d'Arno fauna of northern Italy, is hardly comparable with 

 any American horizon. We are here on the border-line between 

 Pliocene and Pleistocene, and a great deal of research is still needed. 

 The Peace Creek deposits of Florida (Dall) may help us because here 

 we discover an Equus and an Elephas Zone overlaid by marine 

 Upper Pliocene molluscs. Rather primitive forms of Equus and 

 Elephas are also characteristic new arrivals of the Upper Pliocene, or 

 Sicilian, stage of Europe. The same doubt applies to the little- 

 known "Loup River" of Nebraska, in which Equus and Elephas 

 were discovered by Leidy many years ago. 



PLEISTOCENE 



Perhaps the most striking determinations which await the mam- 

 malian paleontologist are those which close comparison of the Pleisto- 

 cene stages in the New and Old Worlds will afford. In Europe we 

 have four great series of correlation data, namely: 



The geologic succession of the glacial depositions; 



The faunal succession especially among the higher mammals; 



The evolution of stone implements of human manufacture; 



Stages in the skeletal evolution of man. 



In America the two kinds of data connected with the evolution of 

 man are entirely wanting, and we are thrown back on the geologic 

 and the faunistic divisions; consequently close comparison in these 

 two lines of evidence common to both countries is all the more neces- 

 sary. In Europe it is possible to distinguish four grand faunistic 

 phases, namely: 



The first early Pleistocene fauna, Eolithic Stage of culture; 



Second or mid-Pleistocene fauna, Eolithic and early Paleolithic 

 Stages; 



Third or Upper Pleistocene fauna, late Paleolithic Stage; 



Fourth, post-Glacial fauna. Neolithic Stage. 



From close study of the Pleistocene life of North America there is 

 promise of correlation with Europe through identification of x\merican 

 with European glacial and interglacial periods, through the discovery 

 and identification of interglacial faunas, as in the Aftonian and 

 Toronto deposits, through the careful recording of the time of extinc- 



