EXTINCT MAMMALS OF ALASKA 79 



conditions. Mr. Maddren urges that there are no facts to sup- 

 port the contention that the climates of the Arctic and 

 sub -Arctic regions ever had been colder than they are at 

 present. He thinks that there are no phenomena presented 

 by the past history of these regions that require a more 

 severe climate than that now existing to account for them. 

 There are no ice deposits in Alaska, he says, except those of 

 large glaciers, that may be considered of Pleistocene age. 

 There are no ice-beds, he continues, interstratified with the 

 Pleistocene deposits of Alaska. Finally he argues that the 

 various forms of land ice, together with the deposits of peat, 

 now existing throughout the Arctic and sub -Arctic regions 

 of Alaska, belong to the Kecent Period, and that these deposits 

 may be most conveniently and logically classified by their 

 position with reference to the Pleistocene and Eecent forma- 

 tions, and that the ice deposits cannot be differentiated satis- 

 factorily into deposits of snow or water origin by their 

 physical structure and character alone.* 



A second Smithsonian expedition to Alaska was dispatched 

 a few years later under Mr. Gilmore. He noticed that the 

 scattered remains of Pleistocene animals occurred throughout 

 the unglaciated region of Alaska and the adjacent Canadian 

 territory in three distinct deposits, viz., in what is locally 

 known as " black muck," which is accumulated in the valleys 

 of the smaller streams, then in the silt and clays already 

 referred to, and finally in the more recent fluvial and alluvial 

 beds. The best-preserved remains were obtained in the muck 

 deposits, and in these occurred certainly several examples of 

 primary entombment. A magnificent skull with tusks of the 

 mammoth was discovered in the muck forty-two feet below 

 the surface, near Dawson, in the Yukon territory in north- 

 western Canada. Mr. Gilmore f is convinced that the 

 determinable species of mammals found are sufficient to 

 show at once that they represent, a typical Pleistocene 

 fauna, some of them, such as the moose, caribou, musk ox, 

 sheep, bear, and beaver, having persisted down to the present 

 day. 



* Maddren, A. Gr., " Smithsonian Exploration in Alaska," pp. 65 66. 

 t Gilmore, C. W., "Smithsonian Exploration in Alaska," pp. 26 38. 



