GEOS 1034 Lecture Notes - Lecture 7: San Bernardino, California, Riprap, Portuguese Bend
18 Aug 2016
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Document Summary
Downslope movement of solid or saturated material: rock, mud, debris, snow. Term is over-simplified: not always land, doesn"t always slide. Areas with moderate relief suffering from soil degration. Areas covered with thick layers of loose, fine-grained materials. At some angle shear = friction: angle of repose. Dependent on material size and water content. Slide: motion along a well-defined surface: translational vs. Transtitional: material slides downslope over top of stronger surface (loose material such as soil over stronger material such as bedrock). Some tree roots may penetrate deep enough to movement. Rotational landslide: deep, homogenous material moves as a relatively coherent mass. Tree roots don"t penetrate deep enough to hinder movement. Flow: moving as a fluid: tongues or lobes a tell-tale clue. Moving randomly as discrete particles: rotational slide + flow = slump. Proportional to drop height: typical values of 1-3x. Slowest form of flow: mm/year: widespread & destructive, yet readily observed.
