GLACIATION 
I 4 I 
Chilkoot Lake (fig. 77), and 3,500 to 4,000 feet near 
Brady Glacier (fig. 61). In the neighborhood of Sitka it 
is about 2,000 feet. 
In a general way this limit records the extreme height 
locally attained by the confluent ice of the Pleistocene. 
As the line often runs among modern neves and glaciers, 
where glacial erosion has been in progress ever since the 
maximum ice flood, there is possibility that the later 
development of cirques has, in places, carved out sharp 
blades and pinnacles from summits that had been rounded 
by the earlier flood, but this qualification is not believed 
to be important. The upward diminution of the paring of 
salient angles is such as would naturally obtain near the 
upper limit of ice action. 
My observations of the limit of rounding are not so dis¬ 
tributed as to give a comprehensive picture of the extent 
of the maximum ice-sheet, 
but they agree fully with 
Dawson’s conclusion that 
the whole district was oc¬ 
cupied. Where now are 
sounds and channels the 
ice depth was probably 
from 3,000 to 6,000 feet, FIG . 67. A FIORD OF THE INSIDE PASSAGE. 
but many summits were The tops of distant mountains were smoothed 
. r o r i 1 and blunted by overriding ice. 
ice-free, borne of the un¬ 
covered peaks were nunataks, about which ice currents 
parted to unite again. Others were the culminating 
points of mountain masses which served as centers of 
glaciation. 
Cirques . — Other features due to ice sculpture are cir¬ 
ques. These occur at all altitudes above 1,000 feet, being 
most abundant in the higher regions. Those above 3,000 
to 3,500 feet now contain neves, and it is probable that they 
have been occupied not only since the last maximum of 
