THE TUNDRAS AND STEPPES OF PREHISTORIC EUROPE. 329 



Siberia — long spells of still weather, with intense frost, interrupted now 

 and again (especially at the changes of the seasons) by fierce snow- 

 storms, in which the wild animals could hardly fail occasionally to 

 perish in large numbers. 



How long these tundra conditions obtained we can not tell. All we 

 know is that eventually they gradually passed away and the climate 

 became less arctic. This is shown by the well-ascertained fact that 

 both in the loss and the contemporaneous cave accumulations remains 

 of the arctic animals are confined to the lowest beds, becoming grad- 

 ually less numerous as we trace them upward, until they finally disap- 

 pear. But before the last of the tundra forms has vanished remains 

 of a steppe fauna begin to occur. In a word, there was no sudden dying 

 out of one fauna and precipitate appearance of another, but a gradual 

 replacement, consequent, doubtless, upon changing climatic conditions. 



All the animals already mentioned as most characteristic of the 

 subarctic steppes are represented in the caves and alluvial deposits 

 of west and middle Europe. Jerboas, pouched marmots, bobacs, and 

 true marmots, tailless hares and others, all formerly flourished in those 

 latitudes. Besides these most characteristic steppe animals occurred 

 many other forms which were not restricted to steppe lands, such as 

 mammoth and woolly rhinoceros, marsh lynx, cave lion, hyena, wolf, 

 common fox, ermine, weasel, badger, reindeer, urus, bison, etc. Many 

 birds also were present— all of them species which in our own day 

 frequent the steppes of southeast Russia. Land shells are also very 

 often found in less or greater abundance along with the relics of the 

 steppe animals just mentioned, most of the shells representing forms 

 that now live in dry steppes, while some are denizens of wooded 

 regions. 



The plant remains associated with relics of the steppe fauna are quite 

 in keeping with the latter, but are upon the whole seldom met with, 

 the conditions not being favorable to their preservation. Trunks and 

 branches of trees occur very rarely, the most common remains being a 

 few thin layers and seams of peaty matter, apparently consisting chiefly 

 of grasses. Nevertheless, we need have no doubt that a steppe flora 

 formerly flourished in middle Europe, for (as Engler, Ascherson, Petry, 

 and other botanists have shown) many well-known steppe plants survive 

 in the existing flora of that region. 



Among the animals associated with the true steppe forms were some 

 which, as we have seen, had already invaded central Europe in tundra 

 times. Of these, perhaps the most notable are the mammoth and the 

 woolly rhinoceros. Probably they were only summer visitors, but in 

 the subsequent steppe epoch they became truly indigenous and very 

 abundant. The broad valleys and open spaces of central Europe were 

 at that time treeless plains, although woods seem to have existed here 

 and there, especially along the margins of lakes and streams. The 

 climate, we need not doubt, was much like that of the subarctic steppes 



