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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL.51 



The working face as we saw it varied from twenty to forty feet in 

 height. It is in the bottom part of the muck that the fossils are 

 found. Those seen in place were from twelve to eighteen inches 

 above the layer of gravel, and upon inquiry it was learned that all of 

 the specimens taken out here had come from approximately the same 

 horizon. 



The muck and gravel, which rest unconformably upon the under- 

 lying rocks, is solidly frozen, but thaws rapidly under the heat of 

 the summer sun, and large pieces were continually dropping during 

 our examination of the face. This thawed material emitted the dis- 

 agreeable odor of decomposing organic matter, a phenomenon 

 observed by many others, particularly Dall, 1 who attributed it to 



Fig. 1. — Cross-section of Fox Gulch, Bonanza Creek, Yukon Territory, Canada. 



a. "White channel" gravels and quartz drift; b. Muck; c. Bed rock; d. Layer 



of logs, limbs, etc. ; x. Level where fossils occur. 



decaying animal flesh or to dung of the mammoth or other herbiv- 

 orous animals. The present writer agrees with Mr. Maddren, 2 who 

 attributes it to the gases from decaying vegetable matter, of which 

 the deposits are largely composed. 



Interbedded with the muck in Fox Gulch was a layer of wood, 

 represented by many fair-sized sticks (see (d), fig. 1), their ends in 

 many instances being much rounded and water-worn. 



Many of the fossils found here were beautifully preserved. For 

 example, several of the bison skulls had the external horn, the entire 

 dentition, and the frail, delicate bones of the anterior portion of the 

 face remaining intact. The conditions are unusual, for, as a rule, 

 only the horn cores and the heavier and stronger parts are found, and' 

 it is upon such fragmentary specimens that the descriptions of most 

 of the extinct species of bison of this continent are based. Stranger 

 still, however, is the fact that here no parts of these animals are 

 found articulated or even so associated that skeletons might be 

 assembled. All of the material is dismembered and scattered. 



1 Dall, W. H. : 17th Ann. Rept. U. S. Geol. Sun., pt. 1, 1895-96, p. 853. 



2 Maddren, A. G. : Loc. cit, pp. 64-65. 



