chapter 10 mass wasting

consider a weathered rock or soil particle lying on a slope. how will the gravitational force pulling the particle downward along the land surface vary with the inclination of the slope?

it will decrease as the slope angle is lessened

how do the strength and cohesion of clay-rich regolith or soil change with the addition of water?

water lowers the strength and cohesion

which of the following types of mass movement often travels as a coherent mass down a curved surface?

slump

some landslides include a mixture of loose sediment and debris called…

regolith

consider a steep highway cut made by removing slightly weathered to fresh, fractured, granite bedrock. which of the following situations is most stable against rockslides?

one set of widely spaced sub-horizontal fractures

which statement best describes slumping, a mass wasting process?

a block or blocks of unconsolidated regolith slide downhill along a curved slip surface

the principal difference between a debris flow and a debris slide is…

that a debris flow contains abundant water, whereas a debris slide is dry

which of the following increases the risk of mass movement?

flooding the sediment with water to the point of saturation

moisture among sediment grains…

can promote stability if present in small amounts

why does adding a small amount of water to a substance increase its cohesion but adding a lot of water decreases its cohesion?

a small amount of water increases surface tension and holds the grain together, too much water between the grains will eliminate surface tension

all of the following are factors affecting mass wasting except for…

geologic age

as an erosional process, how is mass wasting unique from wind, water and ice?

mass wasting does not require a transporting medium

which of the following statements concerning mudflows is NOT true?

mudflows deposit talus slopes

all of the following are possible indicators that creep is occurring except for…

an extremely thick soil profile

which of the following situations may lead to slope failure?

undercutting a slope by a bulldozer

which of the following factors decreases the risk of mass movement?

adding vegetation to the side of a hill

_______ is a region that is plagued by mass wasting events

california

a(n) __________ area would be most likely to experience a slope failure

rugged

a slope in a _______ environment would be much more likely to experience … and thus be more susceptible to slope failure

humid; weathering

which of the following situations is the most likely candidate for the occurrence of mass movements?

a mountain terrain in a humid environment

slope failures are more likely to occur in ____ than in…

mountains; deserts

________ are evidence of the toe of a landslide

hummocky ridges

imagine you have just bought some property and notice that the trees on the slope have curved trunks. what type of landslide event do you likely have on your property?

creep

how can you use a landslide hazard map to help buy a piece of property?

to determine if the property is in a high risk zone for landslide

after finishing a new construction project, why is the first task often to install new landscaping around the area?

the roots will grow into the slope and work to keep the slope intact