'58 



ALASKA GLACIERS 



visit; they are known to me only through photographs, 

 the contour maps of the Canadian Boundary Commission, 

 and the soundings of the United States Coast Survey. 

 As already mentioned, they are judged to be transverse 

 to the strike, because they make wide angles with the 

 general trend of the coast and because they are charac- 



terized by many short 

 turns (fig. 80). Be- 

 ing independent of 

 strike, their courses 

 are also independent 

 of variations in rock 

 texture, and this 

 character makes 

 them specially avail- 

 able for the study of 

 glacial erosion. 

 Their walls are steep; 

 photographs give the 

 impression that they 

 are decidedly steeper 

 than those of Lynn 

 Canal and its 

 branches, but this 

 impression is pos- 



FIG. 80. MOUTH OF spEEL RIVER. 



The river is rapidly filling its deep trough with alluvium, gjpjy due tO the 

 Glacial rounding extends above the base of clouds, which 



cut off the view at about 3,000 feet. ency of photOgraph- 



ers to select localities exhibiting bold scenery. The 

 walls stand well apart, after the habit of glacial troughs, 

 and exhibit notable parallelism (fig. 62). Hanging valleys 

 abound, ranging in height up to 3,000 feet or more and being 

 more numerous at the greater altitudes. Some, like the 

 Stikine and Whiting, are occupied by rivers ; others, like 

 the Taku, Speel, Unuk and Skeena, contain rivers in their 

 upper parts and admit the sea below; others, like Tracy 



