64 



Sierra Club Bulletin 



the process of upheaval ; therefore, a portion of the moun- 

 tain bottom must have suddenly fallen out, letting the super- 

 incumbent domes and peaks fall rumbling into the abyss, 

 like coal into the bunker of a ship. This violent hypothesis, 

 which furnishes a kind of Tophet for the reception of bad moun- 

 tains, commends itself to the favor of many, by seeming to ac- 

 count for the remarkable sheerness and angularity of the walls, 

 and by its marvelousness and obscurity, calling for no investiga- 

 tion, but rather discouraging it. Because we can not observe the 

 bed-rock to ascertain whether or not it is fractured, this engulf- 

 ment hypothesis seems to rest safely under cover of darkness, 

 yet a film of lake gravel and a meadow blanket are its only con- 

 cealments, and, by comparison with exposed sections in other 

 Yosemites where the sheer walls unite with the solid, unfissured 

 bottom, even these are in effect removed. It becomes manifest, 

 by a slight attention to facts, that the hypothetical subsidence 

 must have been limited to the valley proper, because both at the 

 head and foot we find the solid bed-rock. 



The breaking down of only one small portion of the mountain 

 floor, leaving all adjacent to it undisturbed, would necessarily 

 give rise to a very strongly marked line of demarcation, but no 

 such line appears ; on the contrary, the unchanged walls are con- 

 tinued indefinitely, up and down the river cafion, and lose their 

 distinguishing characteristics in a gradual manner easily ac- 

 counted for by changes in the structure of the rocks and lack of 

 concentration of the glacial energy expended upon them. That 

 there is comparatively so small a quantity of debris at the foot 

 of Yosemite walls is advanced as an argument in favor of sub- 

 sidence, on the grounds that the valley is very old, and that a 

 vast quantity of debris must, therefore, have fallen from the 

 walls by atmospheric agencies, and that the hypothetical "abyss" 

 was exactly required to furnish storage for it. But the Yosemite 

 Valley is not very old. It is very young, and no vast quantity of 

 debris has ever fallen from its walls. Therefore, no abyss was 

 required for its accommodation. 



If, in accordance with the hypothesis, Yosemite is the only 

 valley furnished with an abyss for the reception of debris, then 

 we might expect to find all abyssless valleys choked up with the 

 great quantity assumed to have fallen ; but, on the contrary, we 



