"The Discovery of Glacier Bay 



At the mouth of the bay a series of moraine islands 

 show that the trunk glacier that occupied the bay 

 halted here for some time and deposited this island 

 material as a terminal moraine; that more of the bay 

 was not filled in shows that, after lingering here, it re- 

 ceded comparatively fast. All the level portions of 

 trunks of glaciers occupying ocean fiords, instead of 

 melting back gradually in times of general shrinking 

 and recession, as inland glaciers with sloping channels 

 do, melt almost uniformly over all the surface until 

 they become thin enough to float. Then, of course, 

 with each rise and fall of the tide, the sea water, with 

 a temperature usually considerably above the freez- 

 ing-point, rushes in and out beneath them, causing 

 rapid waste of the nether surface, while the upper is 

 being wasted by the weather, until at length the 

 fiord portions of these great glaciers become compara- 

 tively thin and weak and are broken up and vanish 

 almost simultaneously. 



Glacier Bay is undoubtedly young as yet. Van- 

 couver's chart, made only a century ago, shows no 

 trace of it, though found admirably faithful in general. 

 It seems probable, therefore, that even then the en- 

 tire bay was occupied by a glacier of which all those 

 described above, great though they are, were only 

 tributaries. Nearly as great a change has taken place 

 in Sum Dum Bay since Vancouver's visit, the main 

 trunk glacier there having receded from eighteen to 

 twenty-five miles from the line marked on his chart. 

 Charley, who was here when a boy, said that the 

 place had so changed that he hardly recognized it, so 



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