weakens surface rock and makes it more susceptible to pull of gravity. Can be:
Dry or wet
Slow or fast
small or large
free-fall or gradual
function of a driving force, a resisting framework and time. TIME is key variable.
*If driving force is greater tan resisting framework = failure.
Mass movements occur when a geomorphic threshold is exceeded:
Falls and Avalanches
7.5 on Richter scale
Land was displaced 21 feet at its maximum extent
movemet along a planar surface roughly parallel to the angle of the slope.
Madison Canyon example.
occurs when surface material moves along a concave surface. Ex. Slump- when small block of land shifts downward.
When moisture content of material is high.
inplace physcial disintegration and chemical decomposition of rocks at or near the earths surface.
Physical (Mechanical weathering)
outer layers expand more than underlying rock and separate from the rock body
ex. stone mountain, half dome
general process that produces exfoliation domes
-characterized by splitting off of slablike sheets of rock
-occurs because of reduction in pressure when overlying rock is eroded away
plant roots, burrowing animals, humans, etc.
mechanical weathering makes chemical weathering more efficient by increasing surface area.
-Greater the surface = more area for chemical attack.