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. 
