GLACIATION 14! 



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> ^0 6,000 feet, FIG 7< A FIORD OF THE INSIDE PASSAGE. 



but many SUmmitS Were The tops of distant mountains were smoothed 

 ^ f. .. and blunted by overriding ice. 



ice-free. Some 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 



