Deck 15: Mass Wasting

Question 1

What is the angle of repose?

A)The angle of the slip plane from a slide
B)The steepest angle at which a material remains at rest
C)The angle of an inclined rock layer measured from a horizontal line
D)The angle of plunge into the interior

Answer 1

B

Question 2

What is the angle of repose for a sediment such as sand?

A)7°
B)12°
C)33°
D)59°

Answer 2

C

Question 3

Which of the following was the cause of the debris flow in Oso, Washington, in March 2014?

A)Volcanic eruptions generated a lahar.
B)A stream at the base of a slope eroded the toe of the slope away.
C)Heavy rains saturated the surface materials on the slope.
D)The slope was oversteepened during construction.

Answer 3

B

Question 4

Which of the following factors does not influence mass wasting?

A)Gravity
B)Geologic age
C)Water
D)Vegetation

Question 5

Stream valleys are produced through combined effects of mass wasting and running water.If running water alone were responsible for creating stream valleys, how would they appear?

A)Wide valleys with flat bottoms
B)V-shaped valleys
C)Narrow valleys with vertical walls
D)U-shaped valleys

Question 6

Which of the following will not oversteepen a slope and lead to mass wasting?

A)Quarrying
B)Coastal erosion
C)Construction
D)None of these

Question 7

Which of the following locations would be most likely to see large-scale, rapid mass wasting?

A)Florida Everglades
B)Central Illinois
C)Mojave Desert
D)The Rocky Mountains

Question 8

Which region would be most likely to produce a catastrophic landslide?

A)Old, eroded, worn-down mountains
B)V-shaped stream valley with gentle slopes
C)Flat-lying floodplains along a stream
D)Steep, geologically young mountains

Question 9

Which sediment size has the steepest angle of repose?

A)Gravel
B)Sand
C)Silt
D)Clay

Question 10

A ________ is not the sole cause of a mass wasting event, but the last of many causes that initiate the downslope movement of materials.

A)debris flow
B)slide
C)repose angle
D)trigger

Question 11

Which slope composition is the most stable?

A)Unconsolidated sediments
B)Rock layers inclined parallel to the slope
C)Solid bedrock
D)Carbonate rock affected by dissolution

Question 12

What is the controlling force of mass wasting?

A)Water
B)Gravity
C)Friction
D)Hydration

Question 13

Which of the following scenarios would lead to a mass wasting event due to an oversteepened slope?

A)Trees are planted on a slope
B)Heavy rains saturate slope materials
C)Construction of buildings on slopes
D)Baking of surface materials during a wildfire

Question 14

________ is the downslope movement of rock, regolith, or soil under the direct influence of gravity.

A)Mass wasting
B)Erosion
C)Weathering
D)Dissolution

Question 15

Which of the following is not a way an earthquake can trigger mass wasting?

A)Shaking will harden the soils at the surface, which repels flowing water.
B)Shaking creates a landslide.
C)Liquefaction caused sediments to behave like fluids and move.
D)Shaking has created rock falls that have blocked canyons, an effect that will lead to later problems during flash floods.

Question 16

What nongeologic term is commonly used to describe a sudden event in which large volumes of material move down steep slopes?

A)Mass Wasting
B)Carbonization
C)Landslide
D)Lahar

Question 17

Which of the following mass wasting disasters was triggered by an earthquake?

A)Storm King Mountain, Colorado, 1994
B)Colorado Front Range, Colorado, 2013
C)Chengdu, China, 2008
D)Oso, Washington, 2014

Question 18

A stream is flowing over a hill covered in thick soil.The stream is eventually blocked to create a small pond in order to free land downhill for construction.What will ultimately happen to the strength and cohesion of the soil in the area around this pond?

A)Strength and cohesion will decrease.
B)Strength and cohesion will increase.
C)Strength will decrease and cohesion will increase.
D)Neither will be affected.

Question 19

A piece of gravel is resting on a slope.Which of the following best describes how the gravitational force pulling the gravel downward will vary with the inclination of the slope?

A)Gravitational force is not affected by the slope angle.
B)Gravitational force will increase as the slope angle decreases.
C)Gravitational force will only change with the addition of water.
D)Gravitational force will decrease as the slope angle decreases.

Question 20

A stream is cutting into a valley wall.Which of the following is the most likely trigger for a mass wasting event?

A)The stream will saturate the slope and generate a mudflow.
B)The stream erodes the toe of the slope, which results in the slope becoming oversteepened.
C)Upslope trees will be removed, reducing slope strength.
D)The stream will deposit extra sediment on the slope, increasing the weight on the slope.

Question 21

Which type of motion will supply material to and maintain talus slopes?

A)Flow
B)Fall
C)Slide
D)Slump

Question 22

Which scenario led to the disaster that destroyed the city of Armero in 1985?

A)Heavy rains saturated the slopes of Nevado del Ruiz.
B)Flooding eroded the slope of Nevado del Ruiz, oversteepening it.
C)An earthquake shook the slope materials of Nevado del Ruiz loose, causing a landslide.
D)Heat from the eruption of Nevado del Ruiz melted the volcano's ice cap.

Question 23

How is it possible for a landslide to occur without a trigger?

A)Heating from geothermal processes weakens the rock.
B)Long-term weathering weakens the rock past the strength necessary to maintain stability.
C)Slopes are shaken by earthquakes and the materials are loosened.
D)Water migrates along the sediment particles, reducing friction between them.

Question 24

A ________ is an example of a translational slide.

A)rockslide
B)creep
C)mudflow
D)slump

Question 25

What is the slowest form of mass wasting?

A)Slump
B)Debris flow
C)Creep
D)Earthflow

Question 26

What is the crescent-shaped mark found at the top of a slump block?

A)Scarp
B)Ditch
C)Overburden
D)Earthflow

Question 27

What are three examples of preexisting slip planes for translational slides?

A)Slumps, valleys, and mudslides
B)Bedding planes, frost wedging, and permafrost
C)Faults, bedding planes, and joints
D)Water, ice, and crevasses

Question 28

Why is it possible for rock avalanches to move at speeds in excess of 200 kilometers per hour?

A)They are moving with large quantities of water.
B)They are moving with molten material such as lava.
C)They are moving with large quantities of air trapped and compressed beneath the debris.
D)They are moving with large chunks of ice compressed beneath the moving material.

Question 29

Southern California is famous for its wildfires, which are often exacerbated by the Santa Ana winds blowing through the canyons.What mass wasting event will later devastate the same fire-affected areas?

A)Mudflows
B)Rockslides
C)Slumps
D)Solifluction

Question 30

Which factor exerts the greatest control over the velocity of debris flows and the distance they will travel?

A)Debris content
B)Water content
C)Slope angle
D)Vegetation

Question 31

The creation of which sedimentary feature is controlled in part by debris flows exiting a narrow canyon?

A)Fluvial
B)Dunes
C)Lacustrine
D)Alluvial fan

Question 32

Which of the following scenarios best describes the creation of the lahars associated with the eruption of Mt.St.Helens in 1980?

A)Hot gases melted the volcano's snowcap, generating meltwater that mixed with ash.
B)A volcanic flank collapsed in a landslide, which flowed into Spirit Lake.
C)Ash deposited during the eruption was remobilized by a flood years later.
D)The eruption deposited fine ash in the Toutle River.

Question 33

Which would be the most likely location for a rockslide to occur?

A)Rock cliff with no fractures or voids
B)Inclined strata with joints and fractures parallel to the slope face.
C)A soil-covered slope with a stream flowing at the base
D)Bottom of a stream valley with a highly meandering stream

Question 34

A ________ is an example of a rotational slide.

A)rockslide
B)fall
C)mudflow
D)slump

Question 35

What is the fastest form of mass wasting?

A)Slide
B)Slump
C)Creep
D)Rock avalanche

Question 36

A ________ slide is type of mass wasting process where the surface of rupture is a concave-upward curve and descending material exhibits downward and outward motion.

A)translational
B)fall
C)rotational
D)horizontal

Question 37

Which rapid form of mass wasting is found at the base of slump blocks?

A)Debris flow
B)Rockslide
C)Lahar
D)Earthflow

Question 38

A ________ slide is a type of mass wasting process where a mass of material moves along relatively flat surfaces such as joints, faults or bedding planes.

A)translational
B)fall
C)rotational
D)horizontal

Question 39

What combination of factors was responsible for the disaster west of Yellowstone National Park on August 17, 1959?

A)Rock falls filled a lake with debris until the water overtopped the dam and eroded through the concrete.
B)Water migrating along foliation layers in the metamorphic rock destabilized a dam, which collapsed and flooded the valley.
C)A severe earthquake triggered a slide that blocked a river and flooded a campground.
D)Drainage from the reservoir generated a lahar, which destroyed small towns downstream.

Question 40

Which mass wasting process involved volcanically derived material from the eruption of Nevado del Ruiz and destroyed the city of Armero in 1985?

A)Lahar
B)Rockfall
C)Solifluction
D)Debris flow

Question 41

One main cause of creep is

A)melting of ice during a volcanic eruption.
B)oversteepening of a slope due to construction.
C)expansion and contraction of soils during freezing and thawing.
D)collapse due to weight of intense rains saturating the sediment.

Question 42

Postfire debris flows are most common in the first 2 years after a fire.

Question 43

Fast mass-wasting processes are more widespread than slow mass-wasting processes.

Question 44

Creep is a slow type of mass wasting that moves at a rate of a few centimeters per year.

Question 45

Grasses will result in more slope stability than trees.

Question 46

Rockfalls are the primary way in which talus slopes are built and maintained.

Question 47

Rapid mass-wasting events do not always need a trigger.

Question 48

Which location is likely to experience creep?

A)Horizontal plateaus
B)Steep slopes
C)Gentle slopes
D)Steep and gentle slopes
E)Vertical cliffs

Question 49

Mass wasting is possible only with the aid of a transportation agent such as water, wind, or ice.

Question 50

Thick deposits of soil over bedrock are more stable than thin deposits over bedrock.

Question 51

Slow forms of mass wasting such as creep and solifluction are considered slow because they are restricted to gentle slopes and cannot achieve a high velocity.

Question 52

Tilted retaining walls are a sign of a landscape undergoing creep.

Question 53

Solifluction occurs during the warmer months of the melt season.

Question 54

Creep is the most widespread mass-wasting process.

Question 55

Mudflows are big enough to move in any direction, regardless of the orientation of the landscape.

Question 56

How do both weathering and erosion work together to produce significant landforms such as broad valleys?

Question 57

The weathering process of frost action can make a slope less stable.

Question 58

Why won't meltwater infiltrate into permafrost?

Question 59

Low, old, rounded terrain is actively undergoing mass wasting.

Question 60

In what climate(s)is solifluction prevalent?

A)Topics
B)Tundra and subarctic
C)Arid
D)Temperate and humid

Question 61

How did the underlying geology contribute to the Gros Ventre Landslide of 1925?

A)Rains saturated the sandstone and clay that make up the slope.
B)Creep weakened the sandstone making up the slope.
C)Vegetation was removed from the slope.
D)The river that flowed through the valley dissolved the limestone.

Question 62

The great multimillionaire Rich Mahn is building a new mansion on a steep bluff overlooking a languid river below ...or, at least he could look over the river if it weren't for all the trees in the way.Whipping out his cell phone, he calls a local landscaping company and has all of the trees ripped out and the steep slope smoothed back into place.Several months later, Rich is making another phone call, this time to a construction company.It seems that the bluff is eroding away at an alarming rate and the ground that his new house is sitting on is being undermined.What event(s)led to the mass wasting at Rich's house and why?

Question 63

What role does fire play in making mass wasting more severe during subsequent rains?

Question 64

You are driving along a mountain highway built into the side of the mountain.The rock layers making up the slope are oriented parallel to the slope.What are three ways that the slope could be stabilized to reduce the likelihood of landslides?

Question 65

Which one of the following locations would be most likely to have the mass wasting process visible here? (Note: The region is underlaid by permafrost.)

A)Siberia
B)Colorado
C)Japan
D)Kansas

Question 66

How can road construction in mountainous areas exacerbate mass wasting?

Question 67

Assuming this location is near the Arctic Circle, what kind of mass wasting is visible in this image?

A)Mudflow
B)Creep
C)Solifluction
D)Rockslide

Question 68

What geologic factors contributed to the severity of the Gros Ventre Landslide of 1925?

Question 69

Compare and contrast earthflows and debris flows.

Question 70

Identify the mass-wasting event in this image.

A)Mudflow
B)Creep
C)Solifluction
D)Rockslide

Question 71

Identify the mass-wasting event in this image.

A)Fall
B)Lahar
C)Debris flow
D)Slump

Question 72

Evaluate the statement, "All lahars are mudflows, but not all mudflows are lahars."

Question 73

Identify the mass-wasting event in this image.

A)Slide
B)Lahar
C)Mudflow
D)Earthflow

Question 74

Compare and contrast rotational slides and translational slides.

Question 75

Identify the mass-wasting event in this image.

A)Solifluction
B)Lahar
C)Mudflow
D)Slump

Question 76

In which direction is mass wasting occurring in this image? (Note: The perspective is from the side.)

A)From top to bottom
B)From left to right
C)From bottom to top
D)From right to left

Question 77

Identify the mass-wasting event in this image.

A)Fall
B)Rockslide
C)Debris flow
D)Slump

Question 78

How did the debris from the Gros Ventre Landslide of 1925 lead to another disaster in the same region in 1927?

A)Loose debris resulted in a mudflow.
B)The mass movement of sediment contaminated drinking water.
C)The debris blocked the river, creating a lake that later burst.
D)The debris mixed with river water to create a lahar.

Question 79

Imagine you are at the beach, building a sandcastle.Dry sand cannot hold a form, so the addition of water is necessary to build the castle.However, too much water will destroy the sandcastle and cause the sand to flow away in a slurry.This is similar to the role pore water has on sediments in a slope.What role does water play to maintain a slope? What role does water play to cause mass wasting of the slope?

Question 80

Assume this house is located in central Alaska.What did this house do to the local landscape to end up so misaligned?

A)The house shifted because of a mudflow.
B)The weight of the house generated a debris flow.
C)A rockfall knocked the house off its foundation.
D)Heat from the house melted the permafrost below.