Earth Sciences 1022A/B Lecture Notes - Lecture 8: Regolith, Mass Wasting, Solifluction
27 Nov 2015
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Gravity is always pulling rock, regolith, and soil down slopes; Water saturates materials on slopes-reduces cohesion, friction and adds weight. Figure 15. 4 effect of water on mass wasting. Oversteepened slopes: from undercutting, loss of support vegetation removal: plant roots anchor and stabilize soil earthquakes: dislodge slope materials, start landslides. Slump: rotation of a block of slope materials along a sliding surface. Rockslide: common where rock structures parallel slope, provide sliding surface, or where strong rock rests on weaker rock. Figure 8-4 four rapid forms of mass wasting. Debris flow: fast flow of saturated soil and regolith down valleys following heavy rain; includes volcanic ash in lahars. Earthflow: ongoing movement of mud down a hillside after heavy rain or snowmelt. Figure 15. 11 slump occurs when material slips downslope. Creep: gradual downslope movement of soil and regolith by gravity, freezing and thawing. Solifluction: flow in saturated ground above the impermeable rock, clay or permafrost.
