24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5 1 



photographed a tusk protruding from the face a few feet below the 

 top of the escarpment. 



The bases of the bluffs are washed by the stream, and during 

 stages of high water are undermined, causing large masses to break 

 off. The tusk seen by Collier five years previous had disappeared, 

 but a recent slide had exposed the distal end of a femur of Elephas 

 in place about three feet above the underlying stratum of gravel. 

 Other broken fragments were found in the loose clay of the talus 

 along the foot of the bluffs. The silt varies in thickness from thirty 

 to thirty-five feet, and broken and abraded fossil remains occur, scat- 

 tered throughout. The conditions here are not favorable for the 

 securing of good specimens. Bones of Elephas and Bison were col- 

 lected. 



Discussion 



After a review of the conditions prevailing in localities where fos- 

 sils have been found in Alaska and contiguous territory, the writer 

 feels inclined to dissent somewhat from the views expressed by 

 Maddren regarding the most promising collecting grounds. 



Mr. Maddren 1 has advanced the opinion in the following state- 

 ment that the old lake shores offer the greatest inducements : 



"That the fluvio-glacial Pleistocene lakes of Alaska were subject 

 to annual winter freezing, at least at various stages of their existence, 

 there appears no doubt, because scattered apparently indiscriminately 

 through the clays, at varying depths and considerable distances from 

 the former shore lines of these basins, are some mammal remains. 

 Their positions can only be accounted for by supposing they were 

 carried out on the waters of the lakes from the adjacent shores or 

 tributary streams by ice during spring breakups and freshets, there 

 to be dropped by its melting to their present positions interbedded in 

 the silts. There appears no other logical way of explaining the 

 presence of these bones in the lacustrine areas." . . . 



"The main point is that the remains occur in the silts as scattered 

 depositions. 



"The animals from which they were derived probably died about 

 the shores of these lakes, and it is these Pleistocene lake shores we 

 must examine carefully if we are to obtain anything like complete 

 remains of the mammals inhabiting the region at that time." 



There appears to be one objection to this hypothesis as applied to 

 these fine-silt deposits. If the great number of isolated mammalian 

 bones scattered through it were carried out from the shores and 

 tributary streams by ice, it is hard to understand how they could be 



1 Maddren. A. G. : Smithsonian Misc. Coll., vol. xux, No. 1584, 1905, p. 26. 



