1 'J I [. C. RUSSEL1 1 RFA< I GEOLOGY OF ALASKA. 



animal- of the Pleistocene period by the advance of continental glaciers 

 from the smith. 



I venture to suggest that a similar sequent f events will appear in the 



later geological history of Asia when the Burface geology of thai continent 

 ie more fully investigated. 



/' vation of. Fish Remains. — The annual migrations of the salmon in 

 the rivers of northwestern North America are of interest t" the geologist, 

 since they die in vast numbers and arc buried and preserved in the sedi- 

 ments now formii 



I saw lai ge numbers of dead Balmon in the upper Yukon and in the Lewes. 

 The largest number seen was. however, in the Taiya river, near its month. 

 At this place the " dog salmon " were crowding up the stream in thousands, 

 and thousands that had previously made the ascent were already dead. The 



Taiya river has several mouths, and the water in many of these was so shal- 

 low at the time of my visit that the hacks of the Balmon were exposed as 

 they persistently worked their way up stream. 'The waters were falling, so 

 that many [tools and sloughs had ceased to he connected with the main 

 stream. In these somewhat stagnant waters the fish were concentrated bo 

 a- to completely conceal the bottom. The water from the river that reached 

 these pools, already partially filled with mud. was charged with glacial silt, 

 and a deposit of tine sediment was being formed aboul the dead fish, which 

 might, under favorable conditions, completely bury them. Large numbers 



of dead fish also floated down Stream, and must finally have sunk to the 

 bottom in -alt water. As the delta of' the Taiya is growing rapidly, the 

 < ■• ' 1 1 ' I i i i> ' 1 1~ for preserving large numbers of fish, belonging to a few species, 

 are ex© edingly favorable. 



'I"le- occurrence described is in no way exceptional or novel, hut takes 

 place every year in many places. It serves, I believe, to explain the pn 

 ence of large numbers of fossil fishes in certain rock-, a-, for example, in the 

 .V wark By stem, near Boonton, N< w Jersey, where fishes of a class that now 

 inhabit rivers and lake- occur packed together by hundred-, if not by thou- 

 sands, in a fine -hale associated with coarse conglomerates. 



NAVIGATION OF THE YUKON IND ITS TRIBUTARI] 3. 



1 itain Peterson ascended the Yukon last summer with the steamboat 



' Yukon "' a- far a- the mouth of Telly river, which i^ al t one hundred 



miles farther than any steamboat ha- hitherto gone. The trip up the Por- 

 cupine wa- the first venture of a steamboat on that river. 



In ascending the Porcupine we left Port Yukon in the forenoon of August 



led the limit of navigation, about forty mile- below the Ram pari 



H • . :it i u on August ''>. Had tie ascent he. n made a f. w days earlier, 



ince COUld have l„ , Q U ;\\ igated, because the water had recently 



