Travels in Alaska 



vent; some of them so small the trees growing on them 

 seem like single handfuls culled from the neighbor- 

 ing woods and set in the water to keep them fresh, 

 while here and there at wide intervals you may notice 

 bare rocks just above the water, mere dots punctuat- 

 ing grand, outswelling sentences of islands. 



The variety we find, both as to the contours and 

 the collocation of the islands, is due chiefly to differ- 

 ences in the structure and composition of their rocks, 

 and the unequal glacial denudation different portions 

 of the coast were subjected to. This influence must 

 have been especially heavy toward the end of the 

 glacial period, when the main ice-sheet began to 

 break up into separate glaciers. Moreover, the moun- 

 tains of the larger islands nourished local glaciers, 

 some of them of considerable size, which sculptured 

 their summits and sides, forming in some cases wide 

 cirques with canons or valleys leading down from 

 them into the channels and sounds. These causes 

 have produced much of the bewildering variety of 

 which nature is so fond, but none the less will the 

 studious observer see the underlying harmony the 

 general trend of the islands in the direction of the flow 

 of the main ice-mantle from the mountains of the 

 Coast Range, more or less varied by subordinate 

 foothill ridges and mountains. Furthermore, all the 

 islands, great and small, as well as the headlands and 

 promontories of the mainland, are seen to have a 

 rounded, over-rubbed appearance produced by the 

 over-sweeping ice-flood during the period of greatest 

 glacial abundance. 



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