148 



ALASKA GLACIERS 



to cut down its bed far below the profile which limits the 

 action of running water. 



The essence of the explanation is contained in Gan- 



nett's theorem 

 that the glacier- 

 made valley is 

 homologous, not 

 with the river- 

 made valley, but 

 with the chan- 

 nel made by the 

 river. The bot- 

 tom of a river 

 channel is not 

 evenly graded 

 like its flood 

 plain, but it 

 abounds in hol- 

 lows and hills, 

 and the bottom 

 of a glacier chan- 

 nel has irregu- 

 larities that are 

 similar but on a 

 larger scale. 



A phase of the 

 Pleistocene con- 

 dition of these 

 passages is illus- 

 trated along the 

 base of the Fair- 

 weather Range 

 from Icy Cape to Cape Fairweather. A foothill ridge, 35 

 miles long, is separated from the range by a nearly con- 

 tinuous groove. A dozen alpine glaciers descend to the 



FIG. 73. NORTH WALL OF LOWE INLET. 



The inlet occupies a glacial trough entering Grenville Channel 

 from the east. 



