Systematic Asymmetry of Crest-Lines. 279 



SYSTEMATIC ASYMMETRY OF CREST-LINES IN 

 THE HIGH SIERRA OF CALIFORNIA.* 



By G. K. Gilbert. 



The substance of the present paper was communi- 

 cated to the Section of Physiography of the Congress 

 of Arts and Science at St. Louis last September. The 

 section had just Hstened to Mr. Johnson's paper on "The 

 Grade Profile in Alpine Glacial Erosion." Mr. Johnson 

 stated that since his first observations in the Sierra in 

 1883 his ideas as to the explanation of the phenomena 

 had undergone development, and he regretted that he 

 had been unable to revisit the region for purposes of 

 verification. It was therefore a matter of gratification 

 that I was able to supplement his presentation by the 

 statement that during two seasons of exploration in the 

 glaciated district of the Sierra I had found his hypothesis 

 of cirque development by glacial sapping of the utmost 

 utility in the explanation of the topography. It hap- 

 pened also that its utility was illustrated in my discussion 

 of the origin of the special features to which my own 

 communication referred. 



In the higher part of the Sierra Nevada the glacial 

 cirque is a conspicuous feature of the topography. Each 

 main crest of the great mountain mass, as a rule, is 

 bordered on each side by a row of cirques facing out- 

 ward. Separating the cirques on the same side of the 

 main ridge are subordinate ridges or spurs. Gradually 



* Reprinted from the Journal of Geology^ Vol. XII, pp. 579-585. 



