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Show C. Snowslides and Avalanches: I. Types. a. Wild snow; chaotic, formless snow movements occasionally reaching large proportions. Take place as result of abnormal quantity of new, very dry snow. b. Dry: Composed of any or all forms of dry snow. Have distinct pattern, generally starting at a point or narrow break- off, becoming wider and deeper in descent. Move rapidly and when of major proportions can develop destructive air blast. Come down during or shortly after a major storm but cycle may be prolonged by cold weather which retards normal settling. c. Slab: Composed of windpacked slabs and may be soft or hard. Especially prevalent on lee slopes. Unstable condition may persist for long periods. Generally break off on a wide front with angular lines of fracture, descend with great power and speed. Typically, the entire slope moves at once, j- iost dangerous type to skiers. d. Damp: Similar in some characteristics to dry snow avalanches; the break- off at a point, the gradual increase in size during descent. Travel at lower rates of speed, form snow balls and boulders, have a tendency to stop in a pile rather than spread out. Damp type slides which break off on a wide front, like slab, are actually temperature release of slab snow, and would be so classified. e. Wet: Caused by rain, sun action, prolonged thawing conditions. Move comparatively slowly but can attain great size and power. Produce snow boulders and have tendency to become channelized. Sun slides are those directly attributable to sun action generally in connection with a reflector. Largest wet avalanches are produced by rain and general thawing conditions which penetrate to greater depth than sun action. f. Combination: - 125 - |