mass wasting and mass movement mass movement - a general term used to describe the downhill movement...
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MASS WASTING AND MASS MOVEMENT• mass movement - a general term used to describe the downhill movement of material that are known as slides, falls, slumps, flows, and creep
MASS WASTING AND MASS MOVEMENT1. unconsolidated material - those that are loose or uncemented, such as sand and soil2. consolidated material - those that are compacted, cemented, or vegetated soils
• Factors That Influence Mass Movement1.slope of material - the steepness of a slope influences instability in mass
movementi. the steepness of a pile of loose material such as sand has a distinct limit -
angle of reposeii. once the angle of repose is reached, addition of more sand will make the
pile broader but not taller
• Factors That Influence Mass Movement2. internal friction - a material’s total resistance to movement
i. consolidated dry materials are held together by cohesion (attraction of like particles) and adhesion (attraction of unlike particles)
ii. cementation
iii. plant roots
• Factors That Influence Mass Movement3. surface tension
4. moisture contenti. too little limits vegetationii. too much can push grains apart, add weight, or provide lubrication
• Factors That Influence Mass Movement
• Triggers of mass movement1. sudden addition of moisture
• Triggers of mass movement
2. shaking of the ground - liquefaction
• Classification of mass movement1. Based upon
i. nature of the material (rock or unconsolidated) ii. speed of movementiii. nature of movement (sliding, falling, or flowing)
• Rock Mass Movement1. rockfall - free fall of boulders from a cliff
• Rock Mass Movement2. rockslides - sliding of rock down an incline
i. usually due to rock breaking from its host material along a bedding plane, joint, or other structural weakness
• Rock Mass Movement3. talus - debris at the bottom of the slope in a broken mass due to rockfalls and rockslides
• Rock Mass Movement4. rock avalanche - rock becomes broken into pieces before it reaches the foot of a slope
• Unconsolidated Material Mass Movement1. creep - extremely slow, almost imperceptible downslope movement of soil and rock debris
• Unconsolidated Material Mass Movement2. solifluction (soil flowage) - special type of creep that is common in polar regions where groundwater in the pore spaces of soil and rock is permanently frozen
• Unconsolidated Material Mass Movement
3. earthflows and debris flows - consist of mixtures of rock fragments, mud, and water that flow downslope as viscous fluids
• Unconsolidated Material Mass Movement3. earthflows and debris flows - consist of mixtures of rock fragments, mud, and water that flow downslope as viscous fluids
• Unconsolidated Material Mass Movement4. mudflows - a variety of debris flow that consist mostly of small silt and clay-sized particles
i. usually occur after heavy rainii. as much as 30% water content
• Unconsolidated Material Mass Movement5. debris avalanche - fastest unconsolidated mass movement
i. on steep slopes in humid areas
6. slumps and debris slide - movement of material in which the material is not rearranged
Debris Slide
• Plate Tectonics1. OC - CC boundary
i. causes steep slopes
ii. volcanic activity and earthquakes
Gros Ventre
•1925•80 km / hr•Buried 30 m thick
• Impact of Human Activities on Mass Movement1. road construction
2. reservoirs