920 GEOLOGY 



Canada, but since it emigrated to South America and crossed the 

 tropics, it cannot have been ill-adapted to a warm climate. It 

 likewise outlived the glacial period. Williston suggests that while 

 mammoths were abundant in Kansas and on plains where forests 

 did not prevail, mastodons were mostly confined to valleys and 

 timbered regions, 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. Bears, rather recent 

 emigrants from Eurasia, were present, as were wolves and peccaries. 



The southern group. Over against this assemblage of more 

 or less boreal forms pushed southward by glacial advances, there 

 was the group of South American immigrants, the monster sloths, 

 Megatherium, Mylodon, Megalonyx, and the gigantic armadillo 

 Gli/ptodon with a strong carapace and a massive tail plated with 

 spiked ossicles (Fig. 601). The remains of this group have been 

 found chiefly in caverns and crevices, or in the muck and mire about 

 salt springs, or in fluvial deposits, the precise ages of which are 

 difficult to fix. There is apparently nothing in the climatic con- 

 ditions of such an interglacial stage as that which permitted paw- 

 paws and osage oranges to flourish about Toronto, to forbid the 

 presence of these animals in the most northerly ranges in which 

 their relics are found, Pennsylvania and Oregon. 



Pleistocene Life in Eurasia 



The changes undergone by the life in Europe, during the glacial 

 period, were similar to those already sketched for America. 



During the first glacial epoch, a thoroughly arctic fauna lived 

 in the North Sea, while during the first recogni/ed interglacial 

 epoch, the arctic fauna retreated northward. During this inter- 

 glacial interval, a temperate flora, comparable to that now living 

 in England, clothed the British Isles, while the hippopotamus, 

 elephant, deer, and other mammals invaded Britain by way of the 



