Mass Wasting: The Work of Gravity > Concept #2 Quiz
may be the last of many causes that added up to slope instability
causes materials to cross the threshold between stable and unstable
weathering producing loose blocks available to fall downslope
situations that make a slope more susceptible to the pull of gravity
Match the following trigger of mass wasting with the appropriate description:
Using the pulldown boxes, match each item on the left to the corresponding item at right.
causes the reduction of internal resistance of materials to flow downslope by gravity
adds weight to a mass
causes loss of cohesion between unconsolidated particles
small amounts of water destabilizes a slope
water reduces the strength of clays but raises the cohesion of the soil
water lowers the strength and cohesion
water increases the strength and cohesion
water does not affect the cohesion but lowers the strength
Match the trigger of mass wasting with the situation in which it most likely occurs:
an unstable slope, the shallowest angle of which is determined by the gravitational pull on the material
a stable slope, the steepest angle of which is determined by material
a stable slope when unconsolidated material has films of water around each grain
an unstable threshold, the steepest angle of which is determined by the amount of water
amount of water
shape of particles
size of particles
steepness of slope
moist, clay-rich shale layers
moist, sandy soil with a clay-rich matrix
water-filled pore spaces in consolidated materials create a reduction in friction in an inclined layer
water-saturated surface materials are shaken into a fluid form by earthquakes. It usually occurs without warning
water-filled pore spaces in unconsolidated materials create a higher-than-normal stability to a slope, so it gives way in one solid block
water-saturated surface materials are melted in hot groundwater and thus flow downhill as a fluid
Slope materials suddenly give way without warning due to the rapid influx of water.
Slope materials gradually strengthen over time under the influence of gravity settling, and suddenly give way due to increased density.
Slope materials suddenly give way without warning due to the impact of a tsunami on the slope.
Slope materials gradually weaken over time under the influence of gravity and other factors.