478 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1950 



the other hand, we cannot gainsay that the nomadic hunters of that 

 time used the mountain passes during periods of glacial regression. 

 These same passes over the divide were used recently — in fact, are 

 still being used at the present time — by herbivorous mammals, 

 principally caribou in their annual migratory wanderings. 



There is a sharp ecological border between the tundra-covered north 

 slope and the timbered country on the southern side of the divide. The 

 north slope, however, was not always treeless and desertlike, because 

 spruce logs have been found in deposits of Pleistocene age on the 

 coastal plain and along inland rivers (Smith and Mertie, 1930, p. 254) . 

 In contradiction to prevailing beliefs, Skarland feels that the spruce 

 timber could have grown during a glacial stage of the Pleistocene 

 rather than in an interglacial stage or stages (Skarland, n. d., p. 82). 

 He also believes (ibid., pp. 79-81) that the Bering Sea and Arctic 

 regions were warmer during glacial stages than they are today. 



A minor period of warmth in the Arctic in more recent history is 

 called by the geologists and climatologists a Climatic Optimum. It 

 dates back about 7,000 years. This period was marked by a general 

 amelioration of the temperature when it was apparently warmer in 

 the Arctic than it is now (Brooks, 1949, pp. 364, 370). However, we 

 do not have any geological or paleobotanical evidence that it was warm 

 enough to induce the growth of timber on the Arctic slope. Since 

 the time of the period of transitory warmth, the climate had appar- 

 ently become somewhat colder, a fluctuation that recently seems to 

 have swung in the other direction. Investigations have shown that 

 the timber line is again moving northward in Alaska. Griggs 

 (1937, pp. 252-253) has given positive evidence of this. 



There are fossil remains showing that Arctic Alaska had been 

 inhabited during Pleistocene and post-Pleistocene times by many large 

 and small mammals of which many are now extinct. These include 

 the mammoth, horse, bison, bear, moose, musk ox, caribou, and deer 

 among others (Smith and Mertie, 1930, pp. 251-254). According to 

 Skarland (n. d., p. 114) the musk ox became extinct on the Arctic slope 

 of Alaska only about 80 or 90 years ago. 



THE ARCHEOLOGY 



From our consideration of the ecological setting of the problem, 

 we ai"e in a better position to interpret the archeology of northern 

 Alaska against the broader perspective of North American prehistory. 

 Geological interpretations of the archeological work indicate that man 

 dwelt in the High Plains area of the United States over 10 millennia 

 ago. An early cultural horizon, the Folsom, so named from the orig- 

 inal finds at Folsom, N. Mex., falls principally within this category. 

 The Folsom culture is typified mainly by its projectile points. How- 



