i88 



Sierra Club Bulletin 



their head-walls are sheerer; and in general, because the main axis 

 of the Sierra has a northwesterly direction, the summit peaks are 

 more precipitous on the eastern than on the western sides. 



In the case of ice-wombs on the north side of a mountain equally 

 shadowed on the east and west, it will be found that such wombs, 

 other conditions being equal, curve back in a direction a little to the 

 west of south, because forenoon sunshine is not so strong as after- 

 noon sunshine. The same admirable obedience to shadows* is con- 

 spicuous in all parts of the summits of the range. Now, glaciers are 



the only eroders that are thus 

 governed by shadows. 



Figure 6 is a section illus- 

 trating the mode in which the 

 heads (H H) of tributaries of 

 the Tuolumne and Merced gla- 

 ciers have eroded and segre- 

 gated the mountain mass (LM) 

 into two mountains — namely, 

 Lyell and McClure — ^by mov- 

 ing backward until they met at C, leaving only the thin crest as it 

 now exists. 



Mount Ritter lies a few miles to the south of Lyell, and is readily 

 accessible to good mountaineers by way of the Mono plains. The stu- 

 dent of mountain-building will find it a kind of text-book, abound- 

 ing in wonderfully clear and beautiful illustrations of the principles 

 of Sierra architecture we have been studying. Upon the north flank 

 a small active glacier may still be seen at work blocking out and sep- 

 arating a peak from the main mass, and its whole surface is covered 

 with clearly cut inscriptions of the frost, the storm-wind, and the 

 avalanche. Though not the very loftiest, Ritter is to me far the 

 noblest mountain of the chain. All its neighbors stand well back, en- 

 abling it to give full expression to its commanding individuality; 

 while living glaciers, rushing torrents, bright-eyed lakes, gentian 

 meadows; flecks of lily and anemone, shaggy thickets and groves, 

 and polleny zones of sun-filled compositae, combine to irradiate its 

 massive features, and make it as beautiful as noble. 



The Merced spur (see Fig. 5), lying about ten miles to the south- 



* For further illustrations of the above observations on shadows, I would refer the 

 reader to Gardiner and Hoffman's map of the Sierra adjacent to Yosemite Valley, or, 

 still better, to the mountains themselves. 



Fig. 6 



