GEOL 104 Lecture Notes - Lecture 28: Permafrost, Active Layer, Solifluction
18 Apr 2016
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Movement of mass downslope, from higher elevation to lower elevation. Slopes change through time: as a landscape sages, less dramatic downslope movements occur, as time goes on, mass becomes unstable. Controls and triggers: free face cliff is geologically unstable, will become a talus slope of rock fall deposits, gravity is the controlling force, the trigger is not the sole cause; it is the last straw. I. e. cracks due to exfoliation, then water comes, freezes, cracks the rock, mass falls: force increases with slope angle, angle of repose. Can never get a steep angle when piling dry sand because keeps falling down the slope (angle of repost) As sand accumulates along a dune crest, the slope get steeper. Eventually, some sand slides down the oversteepened slope: steepening slopes. Undercutting by stream erosion, removes base of slope and increases angle. Highway cuts into slope, disturbs equilibrium, can result in frequent landslides: other contributing factors.
