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Sierra Club Bulletin 



summit of the range, where it reaches perfection, and is also 

 common throughout the greater portion of the middle region. 

 Avalanches are the feeders of the glaciers, pouring down their 

 dry mealy snow into the womb-amphitheaters, where it is 

 changed to neve and ice. Unless distributed by storm-winds, 

 they cascade down the jagged heights in regular channels, and 

 glide gracefully out over the glacier slopes in beautiful curves; 

 which action gives rise in summer to a most interesting and 

 comprehensive system of snow-sculpture. The detritus dis- 

 charged upon the surface of the glaciers forms a kind of stone- 

 drift which is floated into moraines like the straws and chips 

 of rivers. 



Few of the defrauded toilers of the plain know the magnifi- 

 cent exhilaration of the boom and rush and outbounding ener- 

 gy of great snow avalanches. While the storms that breed 

 them are in progress, the thronging flakes darken the air at 

 noonday. Their muffled voices reverberate through the gloomy 

 canons, but we try in vain to catch a glimpse of their noble 

 forms until rifts appear in the clouds, and the storm ceases. 

 Then in cliff-walled valleys like Yosemite we may witness the 

 descent of half a dozen or more snow avalanches within a few 

 hours. 



The denuding power of this species of avalanche is not 

 great, because the looseness of the masses allows them to roll 

 and slip upon themselves. Some portions of their channels, 

 however, present a roughly scoured appearance, caused by 

 rocky detritus borne forward in the under portion of the cur- 

 rent. The avalanche is, of course, collected in a heap at the 

 foot of the cliff, and on melting leaves the detritus to accumu- 

 late from year to year. These taluses present striking con- 

 trasts to those of rock avalanches caused by the first great pre- 

 glacial earthquake. The latter are gray in color, with a cover- 

 ing of slow-growing lichens, and support extensive groves of 

 pine, spruce, and live-oak; while the former, receiving addi- 

 tions from year to year, are kept in a raw formative state, 

 neither trees nor lichens being allowed time to grow, and it is 

 a fact of great geological significance that no one of the Yo- 

 semite snow avalanches, although they have undoubtedly 

 flowed in their present channels since the close of the glacial 



