284 LIFE OF THE PLEISTOCENE 



succeeded by a period of aridity both in Europe and America in which the first 

 loess deposit occurred." 



That the fauna and flora advanced into the territory laid bare by the reces- 

 sion of the Kansan ice is attested by the wide-spread character of the discovered 

 remains of animals and plants, 124 species being rather definitely recorded; 

 12 plants, 20 vertebrates, and 92 mollusks. Of the plants, all are now living 

 and none is peculiar. The Spermatophytes are the leading type, the Pinaceae 

 furnishing the larger number of species. The Mollusca are largely represented, 

 92 species being recorded, 2 of which are extinct, tho having living representa- 

 tives in the drier portions of the southwest; 40 species are aquatic and 52 

 species are terrestrial. Streams and ponds, as well as rivers, must therefore 

 have been numerous, and moist woodlands as well as drier uplands probably 

 were present: 



As far as the plants and mollusks are concerned the life of the Yarmouth 

 Interglacial interval was very little, if any, different from that of today. The 

 vertebrates, however, tell a different story, for of 20 species represented, at 

 least 14 or 70 per cent are extinct. Giant sloths, horses, peccaries, tapirs, 

 elephants, deer, bison, giant beavers, hares, skunks, and wolves roamed about 

 the country and formed a vertebrate fauna quite different from that of today. 

 The insects, of which only a few wings of beetles are known, will probably tell 

 a similar story when a sufficient number have been discovered and classified. 



The presence of the peccary, giant sloth and tapir point to a climate con- 

 siderably warmer than the present. Other mammals, as the deer, rabbit, 

 skunk, and bison suggest a climate not warmer than that of the present time. 

 The pine, tamarack, and juniper suggest a cooler climate. It is probable that 

 during this interglacial period there was a succession of climates as the ice sheet 

 waned and waxed again — cold, temperate, warm; warm, temperate, cold. 

 That a portion of the country was dry is attested by the loess deposits and 

 their fossils, all pointing to periods of prolonged dryness. The fauna of the 

 loess is discussed at greater length in Chapter X. 



