PLEISTOCENE PERIOD 201 



had been the recipient of a blow on the head, probably 

 from a hatchet. " First Aid," apparently, was available, 

 for medical experts, after careful examination of the skull, 

 declare that some rude sort of operation was performed. 

 What success attended this primitive surgery is unknown. 



A glance must now be taken across the Atlantic, where NORTH 

 North America was left under thick ice. As the ice-sheet AMERICA 

 extended its range, a course of events similar to that of 

 Europe must have taken place, involving great migrations 

 to lower latitudes. 



Not far south of the fringe of the ice-sheet arctic willows, 

 dwarf birches, and other cold-climate vegetation furnished a 

 meagre adornment to the landscape. Here, too, were mam- 

 moths, musk-oxen, reindeer, and other animals inured to 

 cold. Further south, horses, lamas, bison, and mastodons 

 found quarters pleasant enough, save for the wolves and 

 " sabre-toothed " cats that followed them to exile. Cali- 

 fornia, there is reason to believe, became a great rendezvous 

 at this time for glacial refugees. Some of the tapirs, peccaries, 

 mule-deer, and many of the mastodons probably migrated 

 across the Isthmus into South America. In that direction 

 also towards the ancestral home must many descendants 

 of the Pliocene emigrant sloths and armadillos have been 

 retreating. Even in southern latitudes the cold must 

 occasionally have been very severe ; for mammoths- 

 denizens of chilly regions were at times down south as far 

 as Mexico. 



Numerous must the migrations have been ; and there is no 

 reason to suppose that the destruction of animal life was 

 absolutely appalling. The oncoming of the ice was gradual, 

 and the facilities for migration were great. 



In course of time, after several occasional relaxations, ICE RETREAT 

 a persistent rise of temperature set in, and better days were IN NORTH 

 in dawn. AMERICA 



At no time had the thick ice originating in Canada advanced 

 very far into the western States of North America. But in 

 the eastern States it travelled down over five hundred miles. 

 As the ice yielded, Illinois, Iowa, Indiana, Ohio, Michigan, 

 Wisconsin, Minnesota, Pennsylvania, New York, and other 



