3o6 Sierra Club Bulletin 



In order that my readers may have clear conceptions of the 

 distribution and comparative abundance of the above phenom- 

 ena, I will give here a section of the west flank from summit 

 to base between the Tuolumne and Merced rivers, which, 

 though only a rough approximation, is sufficiently accurate for 

 our purposes. The summit region from D to C (Fig. 2) is 

 composed of metamorphic slates, so also is most of the lower 

 region, B to A. The middle region is granite, with the excep- 

 tion of a few small slate-cappings upon summits of the Merced 



and Hoffmann spurs. With re- 

 gard to the general topography 

 of the section, which may be 

 taken as fairly characteristic 

 of the greater portion of the 

 range, the summit forms are 

 sharp and aw^w/ar^ because they 

 have been down-Rowed ; all the 

 middle and lower regions com- 

 prising the bulk of the range 

 have rounded forms, because 

 they have been overflowed. In the summit region all the gla- 

 cial phenomena mentioned above are found in a fresh condi- 

 tion, simply on account of their youthfulness and the strong, 

 indestructible character of the granite. Scores of small gla- 

 ciers still exist on the summit peaks where we can watch their 

 actions. But the middle region is the most interesting, because, 

 though older, it contains ail the phenomena, on a far grander 

 scale, on account of the superior physical structure of granite 

 for the reception of enduring glacial history. 



Notwithstanding the grandeur of the canons and moraines 

 of this region, with their glorious adornments, stretching in 

 sublime simpHcity delicately compliant to glacial law, and the 

 endless variety of picturesque rocks rising in beautiful groups 

 out of the dark forests, by far the most striking of all the ice 

 phenomena presented to the ordinary observer are the polished 

 surfaces, the beauty and mechanical excellence of which no 

 words will describe. They occur in large irregular patches 

 many acres in extent in the summit and upper half of the mid- 

 dle regions, bright and stainless as the untrodden sky. They 



Fig. 



