REPORT OF THE SECRETARY. 15 



liave not I)00ii roiiorted witli those of tlic m;imiiiotli in Alnsk;i, as in Siberia, and 

 it also appears that tho i-eniains of tlie mannnoth in AlasUa are not in as fresh a 

 state of preservation as those found in Sil)eria. which ptiints to the surmise that 

 the mannnoth l)efanie extinct in Alaska before? the last of the species succumbed 

 in Siberia. Associated with the niamniuth were herds of large l)ison and hor.ses. 

 This species of horse may have been tlie last native to North America, the rear 

 guard of the last migration of these animals across the region of Bering Straits 

 to Asia before the land connection disappeared. There was a species of musk-ox, 

 together with sheep and bear. Descendants of the.se last three forms have by 

 adaptive ch.inges survived in these northern regions down to the present time. 

 The relation that the fann.i and flora north <if the area occui)ied l)y glaciers 

 bore to that region in the United States before, during, and after separation by 

 the snow and ice fields; also the relation of forms in .\Iaska to those of Sii)eria, 

 with the time and duration of the hind connection across Bering Straits and 

 their subsequent separation, form a complex problem, the solution of which will 

 re»iuire the accumulation of much material. 



JVIr. Mnddren summarizes his conclusions as follows: 



I. That while I'emnants of the large Pleistocene niainnial herds may have 

 survived down to the Recent period and in some casc;s their direct descendants, 

 as the musk-ox. to the present, most of them became extinct in Alaska with the 

 close of Pleistocene. 



II. The most rational way of explaining this extinction of animal life is by a 

 gradual changing of the climate from more temperate conditions, permitting of 

 a forest vegetation much farther north than now, to the more severe climate of 

 to-day. which, subduing the vegetation and thus reducing the food supply, besides 

 directly discomforting the animals themselves, has left only those forms capable 

 of adajiting themselves to the Recent conditions surviving in these regions to 

 the present. 



III. There are no facts to support the contention that the climate of the Arctic 

 I'ud sub-Arctic regions ever has been colder than it is at present. There are no 

 phenomena presented in those regions that reciuire a more severe climate than 

 that noM- existing to account for them. There are no ice deposits in Alaska, 

 except those of large glaciers, that may be considered of Pleistocene age. There 

 are no ice. beds interstratified with the Pleistocene deposits of Alaska. 



IV. That the various forms of land ice, together with the dei)0sits of peat, 

 now existing through the Arctic and .sub-Arctic regions of Alasi^a belong to the 

 Recent period, and these deposits may be most conveniently and logically classi- 

 lied by their position with reference to the Pleistocene and Recent formations 

 and the ice deposits, cau not be differentiated satisfactorily into deposits of 

 'iiiow or of water origin by their physical structure and character alone. 



THE SMITHSONIAN GIJVCIER EXPEDITION. 



The expedition dispatched by the Smithsonian Institution to the 

 Canadian Rockies and Selkirks, under the immediate direction of 

 Prof. AVilliam H. Sherzer, of the Michigan State Normal School, 

 had a successful season's work on the glaciers along the line of the 

 Canadian Pacific Kaihvay. A selection was made of tho.se five gla- 

 ciers which are at the present time most readily accessible to the tour- 

 ist or the student of glacial geology, and these were found to exhibit, 

 more or less strikingly, tlie characteristics of glaciers throughout 



