44 BUREAU OF AMERICAN ETHNOLOGY [Bull. 182 



Here the character of the mammals is a determining factor. What is a barrier 

 for one is not for another, and conversely what is an open route for one is not 

 for another. The Asia-North American bridge oi)ened the barrier for elephants 

 (mammoths) but not for gazelles. The North America-South America bridge 

 opened the barrier for horses but not for bison. This strongly selective action 

 depending on the position and character of the bridge and the consequent envi- 

 ronmental conditions of it and of its approaches is a rule with few exceptions. 

 Another way of putting this would be to say that the true barrier in such cases 

 was not the presence of a stretch of sea but some less obvious environmental 

 factor, such as climate or vegetation, and that for these animals the apparent 

 bridging of a barrier had no meaning because the true barrier remained 

 untouched. 



Western Alaska is an outlier of Arctic Asia and it was during this 

 interval that the lowlands of Alaska were supposed to have remained 

 unglaciated, making it available for the habitation of any group of 

 people who were accustomed to living in high altitudes. 



Sauer (1944, pp. 534-536) says that : 



If man entered the New World well after the Ice Age,* there is no problem 

 in his dispersal east or south from Alaska. It is only if man came while there 

 were still continental glaciers that there is difficulty about his passage beyond 

 Alaska. 



The corridor by which man may have come from the open lowlands of Alaska 

 to the Plains of the United States is uncertain, as are the times at which this 

 may have been possible. The answer waits on the determination of glacial 

 successions in western Canada. Viewed from south of the border, a late corridor 

 through Alberta does not look promising, because of the Late Mankato drift on 

 the northern Great Plains and the probable ice center over Great Slave Lake. 

 We need to know in detail the drift history of the plains east of the Rockies 

 both in Alberta and in Yukon Territory. An alternative route may be an 

 intermontane corridor through British Columbia and the western Yukon, where 

 rain-shadow conditions possibly facilitated deglaciation or prevented glacial 

 spread. 



The remains (of Early Man) point definitely to hunting cultures. Such 

 people had high mobility and could follow herds of game animals through any 

 corridor that opened between Alaska and the United States, provided that 

 nutritious vegetation speedily reoccupied ice-free surfaces. In the case of 

 Folsom Man, the association of sites with glacial and pluvial deposits have 

 made acute, since the first discovery, the question of the earliest moment at 

 which a gap opened in the Wisconsin ice of Canada through which immigrants 

 might have squeezed. 



If we know nothing of European archeology, an estimate of those folk as 

 going back at least twenty or twenty-five thousand years, such as was made by 



* Radiocarbon dating methods have outmoded this concept. It was formerly thought 

 that the eartiest mlKmnts were hunters but evidence is now accumulating that the earliest 

 comers, dated 24,000 years or earlier, were foodgatlierers who had little knowledge of 

 chipping stone into projectile types or other stone tools but who utilized grinding stones 

 to reduce the wild seeds into monl suitable for human consumption. 



When man first began to make stone tools he pounded one rock with another hoping to 

 knock off just the right chip in the right place. This method is known as percussion 

 flaking. Not being satisfied with this manufacturing method, man then learned that by 

 using either a tine from a deer's horn, a piece of bone, or a very liard piece of wood as a 

 supplementary tool he was able to control his chlp))lug and to throw off smaller and finer 

 chips and to make his stone tools more symmetrical. This method Is called pressure 

 chipping. 



