96 ALASKA GLACIERS 



part of the Harriman from the northwest (pi. xv). No 

 measurements were made, but it is evident from an inspec- 

 tion of photographs that the heights of such features in 

 this neighborhood are approximately the same as in the 

 vicinity of Serpentine and Surprise glaciers, and it is 

 possible that a number of minor glaciers observed on both 

 sides of the fiord constitute with these a general system. 

 Roaring Glacier, between the Cataract and the Harriman, 

 owes the peculiarity suggesting its name to an abrupt 

 change of grade. From a comparatively gentle slope it 

 passes to one so steep that loose masses find no lodgment, 

 and as its movement steadily projects its end beyond the 

 point of inflection, fragments of ice break away and tumble 

 down the steep incline, to gather in a heap far below, where 

 they lie until melted. 



The condition of extreme glaciation to which these phe- 

 nomena point does not belong to the series of modern 

 changes, and will be referred to again in the chapter on 

 the Pleistocene history. Were it of comparatively recent 

 date the fiord would now be destitute of trees, but such is 

 not the fact. It is true that the slopes are bare in the 

 immediate vicinity of the glaciers, and that the valley 

 walls enclosing the greater glaciers the Barry, Serpen- 

 tine, Surprise and Harriman support no trees, but the 

 lower parts of the fiord walls are elsewhere covered by a 

 hemlock forest. 



As to the proper interpretation of the peculiarities of 

 forest distribution the case is not altogether clear. In 

 other localities there has seemed good reason to ascribe 

 absence of forest to recent occupation by ice, but here 

 there is a sort of transition from forest to barren which 

 suggests climatic limitation. In the zone of transition the 

 trees are not young and vigorous, as when invading newly- 

 acquired territory, but scrawny and ill-favored, as though 

 struggling desperately against the attack of hostile condi- 



