. Elementary physical geography;. seare the cases in which the havoc is greatest. Not only iseverything destroyed along the path of the moving snow,but the effects are even more apparent along the edges; forthe blasts of wind set in motion by the avalanche, fell everyvestige of timber, perhaps a thousand feet or more on bothsides. Places that the experienced mountaineers have dis-covered to be possible avalanche tracks, are now artificiallyguarded, in order to prevent, so far as possible, the forma-tion of dangerous snowslides. Another form of avalanche occurs in the Alps at thebeginning of wa
. Elementary physical geography;. seare the cases in which the havoc is greatest. Not only iseverything destroyed along the path of the moving snow,but the effects are even more apparent along the edges; forthe blasts of wind set in motion by the avalanche, fell everyvestige of timber, perhaps a thousand feet or more on bothsides. Places that the experienced mountaineers have dis-covered to be possible avalanche tracks, are now artificiallyguarded, in order to prevent, so far as possible, the forma-tion of dangerous snowslides. Another form of avalanche occurs in the Alps at thebeginning of warm weather. Instead of light, powderysnow, its volume consists of ice and coarse snow mixed withrock waste. The lower part of the snow and ice are under-mined by water as the ground thaws. Finally the wholemass slides down the incline. These avalanches, which donot differ materially from landslides, are rarely destructive. Landslides.—The sudden descent of great masses ofloose rock waste does not differ materially from the ava-. WORK OF AVALANCHES AND GLACIERS 159 lanche. It is the sudden degradation of a highland, andthe transportation of rock waste to a lower level* The small landslides along railway cuts differ but littlefrom those that occur on a larger scale on mountain considerable volume of loose rock, undermined by water,slides to a lower level because coherence is weaker thangravity. Perhaps the loose material may rest on a slopingsurface of rock. Possibly, running water may underminea cliff until the overhang breaks and falls. In a few in-stances the landslide has been many acres in extent. Glaciers.—A great part of the snow that falls on highand steep slopes is either blown into ravines by the windor is tumbled into them by avalanches. In the upperpart of the ravine the snow is light and flaky, but fartherdown it has begun to melt, and instead of crystals it con-sists of little granules of ice, called neve. Still fartherdown the ravine, the neve has a st
Size: 1236px × 2022px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyorkcscribnerss
