668 THE PLEISTOCENE PERIOD 



warm climate also. It likewise outlived the glacial period. Willis- 

 ton suggests that while mammoths were abundant on treeless plains, 

 mastodons were confined mostly to valleys and forests, notably those 

 of the eastern states, the eastern part of the Mississippi basin, and 

 the Pacific coast. 



Several species of horses have been found in western beds 

 referred to the Pleistocene period. A gigantic elk ranged from 

 Mississippi to New York. Two or three species of buffaloes roamed 

 over the Ohio valley and southward to the Gulf, and remains of the 

 musk-ox and reindeer, distinctively arctic animals, have been found 

 as far south as Virginia and Kentucky. 



The southern group. Besides this assemblage of more or less 

 boreal forms pushed southward by glacial advances, there was the 

 group of South American immigrants, the monster sloths, and a 

 gigantic armadillo with a strong carapace and a massive tail plated 

 with spiked ossicles (Fig. 543). The remains of this group have 

 been found chiefly in caverns, in the muck and mire about salt 

 springs, and in fluvial deposits, the precise ages of which are difficult 

 to fix. In the climate of such an interglacial stage as that which 

 permitted pawpaws and osage oranges to flourish about Toronto, 

 there was apparently nothing to prevent these animals from ranging 

 northward to Pennsylvania and Oregon. 



Life in Eurasia 



The faunas of Europe underwent changes similar to those already 

 sketched for America. During the first glacial epoch, an arctic 

 fauna lived in the North Sea, while during the first recognized inter- 

 glacial epoch, the arctic fauna retreated northward. At this time 

 a flora comparable to that now living in England was found in the 

 British Isles, while the hippopotamus, elephant, deer, and other 

 mammals invaded Britain by way of the land bridge which then 

 connected it with the continent. A similar flora and fauna ad- 

 vanced to corresponding latitudes on the mainland. A luxurious 

 deciduous flora lived in the valleys of the Alps, and up to heights 

 which it no longer attains. Toward the close of this interglacial 

 epoch the temperate flora gave place to an arctic flora. 



During the second glacial epoch, according to Geikie, 1 the ice 

 reached its maximum extent in Europe, and arctic-alpine plants 

 occupied the low grounds of central Europe, while northern mam- 



1 The Great Ice Age, Third Edition, pp. 607-615. 



