GLACIAL CANONS. 



Historical Note. — This paper was presented before the Ameri- 

 can Association for the Advancement of Science at the Minne- 

 apolis meeting", where it was kindly read by Mr. Warren Upham 

 in the absence of the author. A brief abstract was printed in 

 the proceedings of that body for 1883, page 238. Subse- 

 quently, Dr. J. E. Hendricks, long editor of The A?ialyst, did the 

 favor of reviewing the mathematical portions, and his sugges- 

 tions are embodied in a note. 



The paper is the fruit of field studies in the Sierra Nevada, 

 mainly in the region about Lake Mono, and of subsequent ofifice 

 work in Salt Lake City, under the direction of L C. Russell, then 

 of the United States Geological Survey, in 1882 and 1883. The 

 paper was not published because it was recognized that one of 

 the most important phases of ice work {i. e., the work at the bot- 

 tom of the Bergschrund involved in the formation of cirques 

 and rock basins) was not adequately treated. It was then, as 

 it is now, the opinion of the author that ice work is concentrated 

 and culminates in effectiveness in cirques, whether at the heads 

 of water-carved tributaries (cyms or coombes) or in amphitheatres 

 below ice-falls due to varigradational irregularities in the ante- 

 cedent water-cut profiles, and that this concentration is proved 

 and the correct analyses of the process suggested by the Bergs- 

 schrund in the one case and by seracs in the other ; but the 

 analysis is difificult, and neither then nor later have opportunities 

 occurred for working it out. Recently this phase of ice work 

 has been taken up by Mr. Willard D. Johnson, who brings to the 

 work a rich fund of observation and an acute and vigorous mind, 

 while at the same time the author finds the promise for the desired 

 opportunity for further study fading away ; so it is deemed 

 best to publish in the present form, leaving extension and appli- 

 cation to others. It may be observed that, while the treatment 



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