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POPULAR SCIENCE MONTHLY 



ing photographs. They are distinctly U-shaped with smooth and 

 regular walls. In spite of their breadth, which is a normal charac- 

 teristic of mature valleys, the enclosing walls, especially in the lower 

 portions, are oftentimes exceedingly steep and even precipitous, a char- 

 acteristic of young, not of mature, stream valleys. Thus the same 

 valley has the characteristics of two stages of development, the breadth 

 of maturity and the steep-sidedness of youth. 



It is evident that such conditions as those which characterize so 

 many of the valleys of the Inside Passage can not be due to normal 

 conditions of stream valley development. The discrepancies and anom- 

 alies are altogether too numerous and striking for such an explanation. 



Fig. 7. The Rock Lip of a Hanging Valley Just West of the Nunatak in Nunatak 

 Fiord. There is a vertical difference of 700 feet between the camera site and the lip of the 

 valley. Photographs 9 and 10 were taken from this lip. Photograph by O. von Engeln. 



If this is true of the origin of the valley forms, it follows that the 

 present outline of the intricate maze of channels on this coast cannot 

 be explained as a result of the drowning of normal stream-made val- 

 leys, as has been so universally believed to be the case. 



It is now quite generally admitted that some of the features which 

 characterize the 'Peaches' of the Inside Passage do not admit of ex- 

 planation as a result of normal stream work. The feature that has 

 been most uniformly admitted, to be abnormal is that of discordance of 

 tributary and main valleys. The explanation of this hanging valley 

 condition as a result of glacial erosion, which this paper is supporting, 

 is not, however, so uniformly accepted; the chief objection of those who 

 have not yet accepted it being their belief that glaciers are incompetent 

 to perform such great work as would be required if hanging valleys are 



