* indirect effects- lake infilling behind dams* rate of soil loss- 7% of soil lost each decade* control of erosion- soil conserving farming practices, terracing, tree planting* the world economy- soil is nonrenewable resource Chapter EightMass Wasting: The movement of regolith and masses of rock down slope under the pull of gravity.-No Carrier: Gravity is the primary force for mass movement. Requires slope.* role of gravity* shear stress (as slope +, tc +)-perpendicular component of gravity (perpendicular to inclined surface)holds in place-tangential component of gravity (parallel to inclined surface)causes to move* shear strength: internal resistance to movement-particle cohesion and plant roots govern* role of water-capillary attraction is cohesive until saturated (failure)Mass Wasting Processes-landslides = down slope movement of rock and/or regolith.* types of mast wasting* slope failure- sudden down slope movement of coherent masses (rocks) (dry)* sediment flows- down slope flow of mixtures (sediment, water, and air)Slope Failure* slump- down/out rotational movement on tilted concave up surface-can be annual event, associated w/ heavy rains or shock (earthquakes)* falls-rockfall- sudden free falling of detached bedrock from a steep slope-debris fall- accompanying regolith and vegetation* slides-rockslide- sudden movement of detached masses across bedding plane-debris slide- accompanying movement across plane of reg. and veg.* talus-body of debris beneath a cliff; settle @ angle of reposeSediment Flows (controlled by)-relative proportion of solids, water, and air-physical and chemical properties of the sediment-steepness of slope-can start and stop* slurry flows- water saturated moving mass (soil & regolith ) (20-40% water)-solifluction- very slow (cm/yr)-debris flow- coarse * sand, poorly sorted, moves along alluvial fan (m/hr)-mudflow- highly fluid, moves along valley floor (km/hr)* granular flows- not water saturated (20%-0% wate...
