philosophy of the subject of glacial corrasion. D. W. John- 

 son's recent paper on Hanging Valleys is instructive. 1 



The Psychological Factor in the History of the Glacial 



Controversy— Those who are familiar with Johnson's 2 simple 

 statement concerning cirques and the "steps" and "treads" 

 which interrupt the floors of Alpine valleys must have felt 

 that he was on the point of making an important discovery, 

 and they must also have felt that the correct explanation 

 of the growth of such profiles would furnish the key to the 

 solution of the problems presented by the peculiar profiles 

 associated with them. Notwithstanding this ' the cirque 

 appears neither to have met with the attention it deserves 

 in literature nor does it appear even to have been treated 

 in the correct dynamical manner. The reason for this is 

 mainly a psychological one. The keenest geological intel- 

 lects appear to have approaeh.-d tin- problem of cirque and 

 " valley step" origins with the fixed idea that each is the 

 product of an uninterrupted agency. Moreover,all attempts 

 at a glacial explanation of the cirque form have been tacitly 

 based upon the assumption that the activities which pro- 

 duced the cirque profiles are in as full operation to clay as 

 in recent times. Yet by such assumption it is possible 

 that effect may have been mistaken for cause. No observer 

 appears to have seriously considered the possibility, or 

 probability, that the cirque has been formed by activities 

 now practically inoperative, neither do they seem to have 

 been aware of the fact that the base of the cirque of to day 

 is partly filled with rock rubbish, while the head is being 



' Johnson, D. W.. "Hanging Valleys," Bull. Atner. Geog. Soc, xli, 

 1909, pp. 665 - 683. 



■ W D. Johnson, " Profile of Maturity," Journ. Geol. Chicago, xn, 

 1904, pp. 569 - 578. 



* See however :— (1) Davis, W. M., " Glacial Erosion in North Wales," 

 QJ.G.S., vol. lit, 1909, pp. 281-350, and pi. xiv. (2) Hobbs, W, H., 

 " Cycle of Mountain Glaciation," Geog. Journ., vol. xxxv, pp. 268- 284. 

 References to literature of cirques are supplied in this note. 



