EXPLORATION IN ALASKA IN I907 GILMORE 25 



selected for distribution in deposits from which all other large frag- 

 ments of detrital materials are absent. 



It might be explained, however, on the supposition that the bones 

 have been carried out from muck deposits in which there is no heavy 

 detrital material. In that event many of these deposits might be 

 considered older than are the silts ; or, the presence of interbedded 

 layers of lignite at the "Palisades" and in the silts of Cooleen basin 

 (which would indicate a local drainage or elevation of these beds at 

 one time) might furnish the necessary conditions for the accumu- 

 lation of animal remains, followed by subsidence and further depo- 

 sition. 



Up to this time the best-preserved remains have been found in 

 the deposits of muck accumulated in gulches and the valleys of the 

 smaller streams. Typical examples of the occurrence of this muck 

 may be seen on Little Minook Creek, near Rampart, Alaska, and 

 Bonanza and other creeks, near Dawson, in Canadian territory. 

 Only a single skull of bison with the horn sheaths preserved is 

 recorded as coming from the silt, while they are of common occur- 

 rence in the muck. Their presence here may be accounted for on 

 the supposition that the animals became mired in the bogs before 

 they became solidly frozen as they are now. This naturally raises the 

 question: If mired down in such a place, why is it that the remains 

 should be so universally scattered? The writer suggests that they 

 may have been separated by the creeping of the muck or peat — a 

 phenomenon familiar to all students of deposits of this nature. By 

 such creeping the muck may have moved considerable distances, 

 particularly where the floor is inclined, as in many of the gulches. 

 From the fact that most of the bones occur in the lower layers of 

 the muck, no matter what the depth of the deposits may be, it is 

 apparent that their specific gravity has caused them to sink to their 

 present resting places. Thus it would not be necessary for the 

 extermination of the fauna to have taken place at one time, as might 

 be inferred by their occurrence at one level. 



It was from the muck forty-two feet below the surface that the 

 skull and tusks, surrounded by other bones of the skeleton of Blephas 

 primigenius shown in plate vn, was obtained. Mr. A. H. Brooks, 

 of the U. S. Geological Survey, tells me of seeing a portion of a 

 skeleton of Elcphas from Woodchopper Creek, Alaska, probably 

 taken from a similar deposit. 



The two instances just cited undoubtedly represent places of 

 primary entombment, and the manner of their occurrence appears to 

 approximate the conditions found in the bogs and swamps in the 



