ROCK GLACIERS IN ALASKA^ 



STEPHEN R. CAPPS, JR. 



It is a generally admitted fact among observers of present-day 

 geologic processes in high latitudes, but one upon which too little 

 emphasis has been placed, that processes of weathering and removal 

 of rock waste in sub-arctic regions are different from the controlling 

 processes of degradation in more temperate regions. Among the 

 better-known special agents of erosion active at high altitudes in tem- 

 perate regions as well as in lower altitudes in sub-arctic regions, is the 

 action of glacial ice. Of the processes not so well understood or 

 appreciated is that of- the flow of soils, or "solifluction," described for 

 Bear Island of the North Atlantic Ocean by J. G. Andersson.^ 

 Mr. Andersson considers " solifluction" to be an important agent in 

 the peneplanation of areas in high latitudes, and the process is without 

 question a most important one in many parts of Alaska. Other 

 processes which, according to Daly,^ may be effective in producing 

 an accordance of summits in mountainous regions, accordances which 

 are generally referred to as indicating dissected peneplains, are frost 

 action, glaciation, and wind erosion, all of which are relatively more 

 effective above the vegetation line than below it. The accordance of 

 summits, it is suggested, is produced by the selective action of these 

 agents in attacking most vigorously the higher peaks. Even the 

 ordinary processes of stream erosion are different from those of tem- 

 perate climates, for the streams are frozen for about seven months 

 a year, and during the open months their action upon the detritus 

 is greatly influenced by the permanently frozen character of the soil, 

 and by ground-ice. 



The special agents of degradation with which I wish to deal at 



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



2 J. G. Andersson, "Solifluction, a Component of Subaerial Denudation," Jour. 

 GeoL, XIV (1906), 91-112. 



3 Reginald A. Daly, "Summit Levels among Alpine Mountains," Jour. GeoL, 

 XIII, No. 2 (1905), 105. 



359 



