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Sierra Club Bulletin. 



a disposition to believe that preglacial forms, including 

 the great canons, had been merely swept clean of decay 

 products and talus, and sound bed-rock smoothed and 

 polished. Of the class of features to which I have to 

 refer as anomalies of grade, only isolated, striking exam- 

 ples received attention; and these were given place in a 

 catalogue of wonders, without attempt at correlation or 

 explanatory description. In the general denial of quanti- 

 tative efficiency in glacial erosion they were left uncon- 

 sidered. 



As a maker of topographic maps, I had the topog- 

 rapher's familiarity with the erosion aspects of moun- 

 tains, though of unglaciated mountains only. By 

 fortunate field association I had acquired as well some- 

 thing of the inquisitiveness of the physiographer as to 

 the origin and development of topographic forms. Yet 

 the scheme of degradation disclosed from the widely 

 commanding summit of Mt. Lyell — the first station 

 occupied in my work of survey in the High Sierra — 

 was one for which I had in no way been prepared. In 

 its dominant characters of ground-plan and grades it was 

 unintelligible. Stream erosion was plainly to be excluded. 

 It is no less clear to me now than upon that first com- 

 prehensive view from Lyell that the development of such 

 characters by the agency of running water is theoretically 

 impossible. 



Most conspicuously in evidence were remnants of 

 an old topography. These were tabular and high-walled, 

 though on closer examination their seemingly flat sur- 

 faces proved to be variously graded. Of inconsiderable 

 area, even collectively, they were none the less striking.* 



* The Dana, Gibbs, and Koip crests, to the northeast of Mt. Lyell, are 

 good examples. In the Bighorn Mountains, in Wyoming, they are larger 

 and more connected. 



