OSBOKN, REVIEW OF THE PLEISTOCENE 219 



together with some discussion as to the period when we should consider 

 that the Quaternary proper begins. The fullness and precision of Eu- 

 ropean faunistic investigation is in very strong contrast to the prelim- 

 inary results of American work, and in no other period may we anticipate 

 more weighty inductions from correlation between the history of the Old 

 and New Worlds. It is absolutely clear that a final and positive time 

 scale and subdivision of the earlv Age of Man are not far distant and 

 that the vast labors of European and American geologists, botanists, 

 zoologists, palaeontologists and anthropologists will finally be rewarded 

 with a harmonious theory of all the phenomena of the Quaternary 

 Period, the determination of the chronology of the various races and an 

 approximate estimate of the duration of the entire Quaternary Period 

 itself. The reader will observe that this correlation, derived from at 

 least five distinct branches of natural science, is based on evidence of four 

 kinds. 



1. Geological : glacial deposits and erosions, which furnish the chief data for 



estimates of time. 



2. Botanical : plant deposits, alternations of northern, arctic, steppe, temperate 



and southern floras, which furnish the chief data for estimates of tem- 

 perature. 



8. Palseozoological : evolution and extinction of mammal and bird life, which 

 furnish the chief divisions of the Quaternary time scale and afford sup- 

 plementary knowledge of conditions of moisture, temperature and foresta- 

 tion. 



4. Anthropological : the successive stages of human culture and implements, 

 the skeletal remains of man, which combined furnish the minor sub- 

 divisions and correlations of Quaternary time. 



Pliocene and Pleistocene Life oe Asia and North Afeica 



life of asia 



The region of the rich Tertiary flood plains of India 2 was one of the 

 main sources of the large mammals which wandered into northern Africa 

 and southern Europe in Pleistocene times; in other words, the large 

 mammals — the elephants, the rhinoceroses, the hippopotami — were all in- 

 vading forms from Asia and Africa. The relations between these three 

 geographic regions are, in fact, so close that they might be embraced in 

 a single zoogeographic realm were it not that throughout the Pleistocene 

 the forests and meadows of southern Europe also maintained a northern 

 Eurasiatic fauna which is entirely absent from southern Asia. 



See p. 323. English edition of "The Age of Mammals. 



