93 



but is not crossed by any well denned mountain 

 range. It is somewhat uniform in appearance, 

 but affords many picturesque and even grand 

 views. Bluffs of rock of a more or less pre- 

 cipitous nature, are of constant occurrence, 

 and bold rampart-like ranges of interrupted 

 cliffs, separated and continued upward by 

 steep grassy or wooded slopes, characterize 

 the banks for long reaches. The flats are few 

 and unimportant, and as a rule the river washes 

 the base of the banks on both sides. The 

 width of the valley varies from one to three 

 miles (i -6 to 4-8 km.), and its depth from five 

 to fifteen hundred feet (150 to 450 m.). Its 

 great size, taken in connection with the hard 

 character of the crystalline rocks through 

 which it has excavated, afford evidence of 

 great age, and point to an origin long antecedent 

 to the glacial period." [50, p. 141 D.] 



Sections of the rock formations are numerous 

 along the valley, but the geology is intricate 

 and difficult. The predominant rocks are 

 schistose and gneissoid types and crystalline 

 limestone all of lower Paleozoic age or older, 

 which correspond to McConnell's Nasina series, 

 Klondike series, and Moosehide diabase of 

 Klondike district. [51, pp. 10 B-23 B]. In 

 places these older rocks have been invaded by 

 various intrusives mainly granite and diabase. 



524 m. Sixtymile River — Sixtymile river joins the 



838 km. Yukon from the west about 23 miles (36 km.) 

 below the mouth of the Stewart. About 17 

 miles (27 km.) below the mouth of Sixtymile, 

 some sandstones and shales, thought to be of 

 early Tertiary (Kenai) age, occur intimately 

 associated with andesitic and rhyolitic vol- 

 canics, and outcrop along the left limit of the 

 Yukon for about 7 miles (10 km.). [51, p. 24B]. 

 These rocks have a considerable development 

 to the west along Sixtymile river. 



571 m. Dawson — Altitude 1,049 f eet (318 m.) 



913 km. Dawson is the principal town in Yukon and is 

 the seat of the Territorial Government. It is 



