CLOSE OF POST- PLIOCENE ADVENT OF MAN. 283 



period of geology may be called the Glacial era. It is 

 that of a cold climate, accompanied by glaciation and 

 boulder deposits. (2) The later Post-pliocene may be 

 called the Post-glacial era. It is that of re-elevation of 

 the continents and restoration of a mild tempera- 

 ture. It connects itself with the pre-historic period 

 of the archaeologist, inasmuch as remains of man and 

 his works are apparently included in the same deposits 

 which hold the bones of Post-glacial animals. (3) The 

 Modern era is that of secular human history. 



It may be stated with certainty that the Pliocene 

 period of geology affords no trace of human remains 

 or implements; and the same may I think be 

 affirmed of the period of glaciation and subsidence 

 which constitutes the earlier Post-pliocene. With 

 the rise of the land out of the Glacial sea indica- 

 tions of man are believed to appear, along with 

 remains of several mammalian species now his con- 

 temporaries. Archaeology and geology thus meet 

 somewhere in the pre-historic period of the former, 

 and in the Post-glacial of the latter. Wherever, 

 therefore, human history extends farthest back, and 

 geological formations of the most modern periods 

 exist and have been explored, we may expect best to 

 define their junctions. Unfortunately it happens 

 that our information on these points is still very 

 incomplete and locally limited. In many extensive 

 regions, like America and Australia, while the geo- 

 logical record is somewhat complete, the historic 

 record extends back at most a few centuries, and the 



