what are mass wasting and mass movement ? Describe their action with diagrams
Answers
Explanation:
MASS WASTING AND MASS MOVEMENT
mass movement - a general term used to describe the downhill movement of unconsolidated material that are known as slides, falls, slumps, flows, and creep
unconsolidated material - those that are loose or uncemented, such as sand and soil
consolidated material - those that are compacted, cemented, or vegetated soils
mass wasting - all processes by which masses of rock and soil move downhill under the influence of gravity, eventually to be carried away by other transporting agents
Factors That Influence Mass Movement
slope of material - the steepness of a slope influences instability in mass movement
the steepness of the a pile of loose material such as sand has a distinct limit - angle of repose
once the angle of repose is reached, addition of more sand will make the pile broader but not taller
internal friction - a material's total resistance to movement
consolidated dry materials are held together by cohesion (attraction of like particles) and adhesion (attraction of unlike particles)
cementation
plant roots
surface tension
moisture content
too little limits vegetation
too much can push grains apart, add weight, or provide lubrication
Triggers of mass movement
sudden addition of moisture
shaking of the ground - liquefaction
Classification of mass movement
Based upon
nature of the material (rock or unconsolidated)
speed of movement
nature of movement (sliding, falling, or flowing)
Rock Mass Movement
rockfall - free fall of boulders from a cliff
rockslides - sliding of rock down an incline
usually due to rock breaking from its host material along a bedding plane, joint, or other structural weakness
talus - debris at the bottom of the slope in a broken mass due to rockfalls and rockslides
rock avalanche - rock becomes broken into pieces before it reaches the foot of a slope
Unconsolidated Material Mass Movement
creep - extremely slow, almost imperceptible downslope movement of soil and rock debris
solifluction (soil flowage) - special type of creep that is common in polar regions where groundwater in the pore speaces of soil and rock is permanently frozen
earthflows and debris flows - consist of mixtures of rock fragments, mud, and water that flow downslope as viscous fluids
mudflows - a variety of debris flow that consist mostly of small silt and clay-sized particles
usually occur after heavy rain
as much as 30% water content
debris avalanche - fastest unconsolidated mass movement
on steep slopes in humid areas
slumps and debris slide - movement of material in which the material is not rearranged
Plate Tectonics
OC - CC boundary
causes steep slopes
volcanic activity and earthquakes
Impact of Human Activities on Mass Movement
road construction
reservoirs
