GLACIAL EROSION IN ALASKA 



"5 



of a Colorado Canyon. The objections to ice as an agent of profound 

 erosion remind one very much of the objections which, in the early 

 days, were urged against water as an agent of erosion. In this con- 

 nection reference may be made to a short note, signed H. G., on page 

 249 of the National Geographic Magazine, Vol. 16, 1905. This little 

 squib, which we may fairly safely ascribe to Henry Gannett, although 

 written in a humorous and somewhat sarcastic vein, is really a note- 

 worthy contribution to the discussion on glacial erosion. In it, as a 

 sort of reply to a recent arraignment of glacial erosion, he applies to 

 the now accepted belief in river erosion some of the same class of 

 arguments as those which have been urged against glacial erosion, and 

 with telling effect. 



Since the establishment of the theory of profound glacial erosion 

 is the work of the last fifteen years, and since the full force of the 

 evidence has only recently been accepted by some of our leading physi- 

 ographers, it is natural that as yet there should not be universal accept- 

 ance of so new an idea, carrying with it such tremendous consequences. 

 But the fact that some workers have not yet accepted the doctrine does 

 not necessarily constitute a strong argument against it, and certainly 

 not enough to counterbalance the overwhelming evidence in its favor. 

 When a large number of people are involved, ultraconservatism is 

 always to be expected among some of them. There are, for example, 

 even at the present day, some highly intelligent men who are writing 



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Fig. 13. The North Wall of Hidden Glacier Valley, a Tributary to the Yakutat 

 Bay Inlet, the Glacier Terminus Showing in the Midground. Note the smoothed, 

 striated lower walls due to glacial erosion as contrasted with the irregular topography of the 

 higher slopes due to ordinary weathering and stream erosion. A hanging valley enter- at 

 about the level between these two classes of slopes about a third of the way from the right 

 margin above the glacier. Photograph by R. S. Tarr. 



