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Chapter 8

Concept #2 Quiz

Concept #2 Quiz
Choose the best possible answer to the following questions about Key Concept 2 "Triggers of mass wasting."

This activity contains 10 questions.

	Which of the following is NOT considered a “trigger” of mass wasting?   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 pull-down menus, match each item in the left column to the corresponding item in the right column. reduction of internal friction in materials due to lubrication produce ground shaking increases the gravitational instability of materials its absence removes underground binding of soil and regolith it can remove stability of slopes due to destruction of plants 2.1 earthquakes A B C D E 2.2 fire [hint] A B C D E 2.3 vegetation A B C D E 2.4 oversteepened slopes A B C D E 2.5 water A B C D E

	Which of the following is NOT a way in which water may trigger or cause mass wasting?   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

	How do strength and cohesion of clay-rich regolith or soil change with the addition of water?   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: Using the pull-down menus, match each item in the left column to the corresponding item in the right column. a stream or waves undercutting a valley or cliff wall all of these a hurricane occurring over steep slopes of unconsolidated soil in locations where forest removal has destroyed the binding of soil in dry areas where forest is found on steeper slopes 5.1 fire A B C D E 5.2 vegetation A B C D E 5.3 oversteepened slopes A B C D E 5.4 water A B C D E 5.5 people A B C D E

	Which of the following best describes “angle of repose,” and what is its significance to mass wasting?   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

	Which of the following does the “angle of repose” depend upon for a given material? Choose the two that apply.   steepness of slope shape of particles size of particles amount of water

	Which of the following materials has the maximum sustainable slope angle, as determined by the angle of repose?   unfractured granite moist, clay-rich shale layers moist, sandy soil with a clay-rich matrix dry sand

	What is “liquefaction,” and why is it a major cause of property damage, potentially?   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

	How might an event of mass wasting occur without a triggering cause?   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.

Some questions in this exercise may have more than one correct answer. To answer such questions correctly, you must select all the correct answers. Also note that answer choices in this exercise appear in a different order each time the page is loaded.

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