GEOL 102 1st EditionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Lecture 14 Outline of Last Lecture I. Mass Movement RelevanceII. Styles of Mass MovementOutline of Current Lecture I. Mass MovementsII. Setting the Stage for Mass MovementCurrent LectureI. Mass MovementsDebris flows are a mixture of water, fine to coarse sediment, and sometimes large woodA fluidized core is resisted by friction-dominated flowCharacteristics of “flow” movementsInitiates in soils or weathered rocksTriggered by intense rainfall or snowmeltHigh water content leads to fluid-like behaviorFollows topography on high velocityDeposits on flat groundFast mass movements RockslidesDetached rock, high velocity, steep environmentTravels as a coherent mass, initiates along plane of weaknessRockfallsFailure of fractured rock on steep cliffs due to: frost processes, earthquakes, precipitation,wind, thermal stresses, lightning, tree ring growth, human activityAttain very high velocitiesRockfalls in YosemiteDetachment and rapid downward movement of rock along steep, glacier-carved cliffs2006-2013 average is about 43 rockfalls per yearMassive piles of rock debris at the base of the valley reveals active sitesII. Setting the Stage for Mass MovementsReliefDifference in elevationGravity can be exploitedCreated by geographical timescales and human timescalesFragmentation and Weathering of RockIntact rock is very strongFractures decrease strengthMountains are like big sand pilesAnalyzing StabilityGravitational forces vs frictional forcesFriction provides stability via interlocking bumps on rock
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