THE 



POPULAR SCIENCE 



MONTHLY 



FEBRUARY, 1907 



GLACIAL EBOSION IN ALASKA 1 



By Professor RALPH S. TARR 



CORNELL UNIVERSITY 



TTT HEN" Henry Gannett made the statement that " thousands of 

 v ' cubic miles " of rock had been removed from the fiords of south- 

 eastern Alaska by glacial erosion, and that " the relief features of this 

 region, its mountains and its gorges partly filled by the sea, are all of 

 glacial origin," - it is probable that many readers had the feeling that 

 he had greatly exaggerated the case of glacial erosion. For my own 

 part, I distinctly remember reading this with the feeling that, although 

 glaciers are unquestionably capable of doing great work of erosion, it 

 would require the most convincing evidence to satisfy me of even the 

 approximate accuracy of this statement. Having now made four 

 trips over a part of the route upon which Mr. Gannett based his 

 statements, and having examined the phenomena attentively, there and 

 elsewhere, I have the conviction that in reality his statement of the 

 case is in close harmony with the truth. It is the purpose of this paper 

 to state the argument upon which this conclusion is based. 



It is a well-known fact that it is possible to go from Seattle to 

 Sitka, along a series of ' Channels/ i Canals ' and ' Reaches ' without 

 once entering the open ocean. In addition to this unique ' Inside 

 Passage' of upwards of 1,000 miles, there is a maze of branches of 

 such enormous extent that the whole system of channels has not yet 

 been charted. Everywhere these arms of the sea are enclosed between 



1 Published by permission of the Director of the U. S. Geological Survey. I 

 am indebted to Lawrence Martin and 0. von Engeln, members of my expeditions, 

 for photographic work, as indicated under the illustrations, and to Mr. Martin 

 and B. S. Butler for valuable assistance in my field investigations. 



2 Harriman Alaska Expedition, Vol. II., History, Geography, Resources, 

 1902, pp. 258-259. 



