34 Smithsonian Exploration in Alaska in 1904 



freezing of even the deepest ice stratum reported in the Arctic might 

 have resulted directly from a mean annual temperature no lower than 

 now prevails in northern Alaska." 



The writer thinks it safe to reiterate that the most severe climate 

 we are justified by facts in assigning to the Arctic is that prevailing 

 there today. 



Page 132 (op. cit.) " Although the passage of heat through the 

 surface layers in Arctic regions is slow, yet it is apparent that the 

 length of time since a mild climate existed there is sufficient, even 

 under existing conditions, to allow of the freezing of strata several 

 hundred feet below the surface. The mean annual temperature of 

 the non-glaciated portion of Alaska during the Glacial epoch must 

 have been lower than at present — at least such I am confident would 

 be the conclusion of the majority of geologists — and there seems 

 good reason for believing that the freezing of the tundra began in 

 Pleistocene times and continued to the present day. An increase 

 in the thickness of the frozen layer, owing to the influence of a 

 mean annual temperature below 32° F., and the deposition of a suc- 

 cession of frozen layers, as suggested elsewhere, may have combined 

 to produce the results now observed." 



The writer cannot agree with the supposition that " The mean 

 annual temperature of the non-glaciated portion of Alaska during 

 the Glacial epoch must have been lower than at present." There 

 are no facts to support such a view. Neither is this surmise justi- 

 fied — " and there seems good reason for believing that the freezing 

 of the tundra began in Pleistocene time and continued to the present 

 day " — for there is nothing to show that a tundra mantled surface 

 of the non-glaciated area was the condition prevailing in Pleistocene 

 time. In Siberia the flora of Pleistocene time north to the present 

 Arctic coast line was not what is classed as tundra. In Alaska, too, 

 the Pleistocene lignites tend to show that a more temperate flora 

 extended considerably farther north than today and there is nothing 

 to indicate that tundra existed at all until the Recent period com- 

 menced. The Avriter considers that all of the peat and tundra of 

 Alaska belongs to the Recent. That the climatic conditions inaugu- 

 rating this period were the first of enough severity to suppress vege- 

 tation to the character called tundra. 



2. A. C. SEWARD QUOTED 



A. C. Seward '" under the heading, " Plants and Low Tempera- 



^ Fossil Plants as Tests of Climate. Cambridge Univ. Press, London, 1892, 

 p. 44. 



