Deck 14: Mass Wasting: The Work of Gravity

Question 1

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

A)Water does not affect the cohesion but lowers the strength.
B)Water reduces the strength of clays but raises the cohesion of the soil.
C)Water increases the strength and cohesion.
D)Water lowers the strength and cohesion.

Answer 1

D

Question 2

When descending cohesive material moves "en masse" along a curved surface of rupture that just formed, it is termed a ________.

A)creep
B)flow
C)slump
D)sag

Answer 2

C

Question 3

What will the long term effect of mass wasting be on oversteepened slopes?

A)It will cause the steep slopes to retreat uniformly, widening the valley but keeping the steep slopes at the margins.
B)It will eventually restore an equilibrium profile by reducing the slope angle.
C)It will fill in the lowland up to the level of the surrounding highland region.
D)It will perpetuate catastrophic mass failures until the entire highland region is removed

Answer 3

B

Question 4

The angle of repose in unconsolidated materials varies from ________ depending on the size and cohesion of particles.

A)2)5° to 4.0°
B)5° to 14°
C)25° to 40°
D)50° to 90°

Question 5

Which statement best describes slumping, a mass wasting process?

A)A block or blocks of rock and/or unconsolidated regolith slide downhill along a curved slip surface.
B)Blocks of hard bedrock rapidly slide downhill on the slope surface.
C)The soil and regolith move downhill very slowly.
D)A mass of soil or regolith becomes saturated with water and suddenly flows downhill to the base of the slope.

Question 6

Which one of the following materials has the maximum, sustainable, slope angle, as determined by the angle of repose?

A)unfractured granite
B)moist, sandy soil with a clay-rich matrix
C)dry sand
D)unsorted, crushed rock used for highway paving

Question 7

Which natural factors routinely weaken slope materials and make them more prone to mass wasting and failure?

A)ablation, chemical weathering, and terracing of slopes
B)devegetation, oversteepening, saturation, and vibrations
C)erosion, sedimentation, and lithification
D)temperature changes and tidal variations in gravitational acceleration

Question 8

What is the major and immediate controlling force in mass wasting?

A)Chemical weathering as bonds fall apart, weakening minerals.
B)Convection, as this drives mantle convection and tectonic uplift.
C)Coriolis force, as it controls cyclonic winds and transport of precipitation.
D)Gravity, as this pulls matter downhill.

Question 9

How do forest or wild fires contribute to mass wasting?

A)by removing stabilizing vegetation
B)via wind transport of fines during the fire
C)by unloading the slope and reducing the rate of mass wasting
D)Human disturbance caused by fire fighting activities is the most destructive and leads to further slope failures.

Question 10

All of the following are factors affecting mass wasting except for ________.

A)gravity
B)water
C)slope angle
D)geologic age

Question 11

How does water affect the internal cohesion of clay-bearing soils and regolith?

A)The soil or regolith has more internal cohesion when wet than when dry.
B)The soil or regolith has less internal cohesion when wet than when dry.
C)The soil or regolith has equal internal cohesion when wet or dry.
D)The soil or regolith has no internal cohesion when wet or dry.

Question 12

Excavated road cuts or quarry faces, and eroding natural river bluffs and sea cliffs, are all examples of ________ which can lead to mass wasting.

A)landscape stabilization
B)oversteepening
C)lithospheric hydration
D)vivisection

Question 13

How are talus slopes built?

A)by glacial transport
B)by rock falls
C)by debris flows
D)between major earthquakes by intense low temperature chemical weathering

Question 14

________ describes the downslope movement of cohesive material along a well defined surface such as a joint or a bedding plane.

A)Avalanche
B)Fall
C)Slide
D)Woo hoo!

Question 15

How do mass wasting processes differ from erosional ones?

A)Mass wasting is always very fast and catastrophic whereas erosion is always slow and gradual.
B)Erosion usually requires steep slopes whereas mass wasting can happen even on flat terrains.
C)Mass wasting is a spring and summer phenomenon while erosion is year around.
D)Mass wasting does not require a transport agent such as wind, water, or glacial ice.

Question 16

Frost wedging and thawing on vertical cliffs produces ________.

A)alluvial fans
B)debris flows and torrents
C)fast moving rock glaciers
D)talus cones

Question 17

What two properties of rain water and snow melt have the greatest effect on soil strength and slope stability?

A)acidity and strong dipole forces
B)electric conductivity and viscosity
C)increased lubrication and added weight
D)solvation properties and surface tension

Question 18

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?

A)It will increase as the slope angle is decreased.
B)It will decrease as the slope angle is decreased.
C)It is not affected by the slope angle.
D)It will decrease as the slope angle is increased.

Question 19

Which statement best describes liquefaction?

A)Upon intense shaking, surface materials lose their strength and behave as fluid-like masses that flow.
B)High volumes of liquid are injected into the ground, eliminating its cohesion.
C)Coal beds are heated and liquified for fuel.
D)Deep-sea sediments lose water during subduction which liquefies overlying mantle rock.

Question 20

What do slumps, rockslides, debris flows and earthflows all have in common?

A)They all happen in frozen soils on steep slopes.
B)They all require water for lubrication.
C)They all transport on a cushion of compressed air.
D)They are all forms of mass wasting.

Question 21

Which of the following mass movements is most likely to occur in a geologic setting where the rock strata are inclined?

A)debris flow
B)slump
C)creep
D)rockslide

Question 22

What kind of feature is commonly found at the base of slump blocks?

A)Debris flow
B)Talus slope
C)Creep ridge
D)Earthflow

Question 23

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?

A)one set of widely spaced, sub-horizontal fractures
B)two sets of fractures, one inclined toward the road and the other into the slope
C)two sets of fractures, one widely spaced and sub-horizontal, the other inclined towards the highway
D)three sets of closely spaced angular fractures

Question 24

What term denotes the exposed slip (fracture)surface beneath a slump block?

A)scoop
B)sole
C)toe
D)scarp

Question 25

What are the most serious mass wasting hazards in mountain valleys?

A)airborne rockslides
B)debris flows
C)glacier bursts
D)rock bursts

Question 26

During wet weather or times when snow is melting, what sometimes happens to the downhill toe of a slump?

A)It turns into a rock avalanche.
B)It becomes an earthflow.
C)It stops moving because water makes the clay sticky.
D)It collapses and is deposited as talus at the base of the slope.

Question 27

________ of soil and regolith commonly flow gradually downhill in humid areas following heavy rain.

A)Earthflows
B)Glowing avalanches
C)Turbidity currents
D)Lahars

Question 28

Which mass wasting process has the fastest rate of movement?

A)slump
B)rockslide
C)solifluction
D)earthflow

Question 29

Rockslides tend to be more common ________.

A)as soon as hot weather comes and rock surfaces dry out so they can slip freely
B)during the spring thaw when heavy rains and melting snow are prevalent
C)in the winter because ice is so slippery and prone to pressure induced melting
D)where rock layers are horizontal or gently inclined and more easily made to slip

Question 30

What is the physical mechanism that drives creep?

A)erosion and sedimentation
B)freeze/thaw or wet/dry cycles
C)gravity fluctuations during earthquakes
D)overbearing slopes

Question 31

What two geologic factors prepared Turtle Mountain or made it prone to slides like that of April 29, 1903?

A)active volcanism and an earthquake
B)heavy rain and snowpack melt, causing debris flows
C)oversteepening of the mountain by glacial erosion and well-developed joints in the rocks
D)Blackfoot hex on the mountain, and excessive game trails

Question 32

Slumps characteristically have ________ and move downslope ________ in a series of ________.

A)steep talus cones, in sudden jumps, inclined planes
B)flat planar sheets, in discreet slip events, earthquake induced movements
C)headwall scarp, coherent mass, rotational blocks
D)overlapping lobes, by very slow creep, annual to decadal events

Question 33

How do freezing, thawing, wetting, and drying contribute to soil creep?

A)The soil becomes much weaker when dry and frozen.
B)Gravity exerts a much stronger force when the soil is wet and thawed.
C)The soil expands and contracts, lifting particles then lowering them a slight distance downslope.
D)Eventually these cause the soil and regolith to suddenly slide down the slope.

Question 34

Slumps are a common form of mass wasting particularly in ________.

A)angular rocky rubble on steep bedrock slopes
B)cohesive water saturated unconsolidated soils and clayey sediments
C)fluidized debris in steep canyons
D)granular sands and gravels

Question 35

Which of the following remedies are not used to stabilize rock faces along the Sea-to-Sky highway?

A)rock bolts
B)metal screens (mesh)
C)sprayed cement
D)fluid injection

Question 36

Which mass wasting process has the slowest rate of movement?

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

Question 37

Which of the following statements concerning debris flows is not true?

A)Debris flows may be caused by heavy rains or melting snow.
B)In hilly areas, debris flows move down the canyons and stream valleys.
C)Debris flows deposit talus slopes.
D)Debris flows can move and carry very large boulders and other coarse debris.

Question 38

Which rockslide dammed the Madison River and buried a campground?

A)Montana 1959
B)Alberta 1903
C)Missouri 1811
D)Quebec 2010

Question 39

Which mass-wasting event involves movement on a zone of compressed air?

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

Question 40

Which of the following travels on compressed air and are usually triggered by earthquakes?

A)rockfall
B)slump
C)solifluction lobe
D)rockslide

Question 41

The significance of mass wasting processes can be seen in that most river valleys are broad rather than "V shaped" because mass wasting slope failures exceed stream erosion.

Question 42

The steepest, stable, slope angle possible in unconsolidated, granular materials like sand and gravel is called the angle of retention.

Question 43

All of the following are possible indicators that creep is occurring except for ________.

A)tilted fences or power line poles
B)a thick soil profile
C)curved tree trunks
D)cracks in roads or sidewalks

Question 44

Triggers are the first step in a mass wasting event that leads to great damage.

Question 45

A triggering mechanism, such as heavy rains or an earthquake, are necessary for mass wasting to occur.

Question 46

Why was the Alaskan pipeline built above ground and insulated?

A)to protect the pipeline from damage by caribou migration
B)to protect the pipeline from damage by volcanism
C)to protect the pipeline from damage due to thawing ground and to keep the oil fluid
D)to protect against damage from roots of large trees uprooted in windstorms

Question 47

What is the chief mass wasting concern associated with permafrost?

A)Debris flows of ice and soils occur frequently.
B)Frozen soils fail and slide like fractured bedrock.
C)Ice in the frozen soils is low density and low strength, failing by fracture under any applied load.
D)Manmade structures tip, sag, and slide when the permafrost melts because of insulation or heating associated with the structures.

Question 48

Most sediment produced by mass wasting is eventually transported back to its source.

Question 49

A geologist wants to locate a horizontal coal bed on a soil-covered slope where soil creep is active.A distinctive sandstone bed underlies the coal bed.On the basis of weathered sandstone fragments in the soil, where is the coal bed?

A)just below the lowest piece of sandstone seen in the soil
B)just above the highest piece of sandstone seen in the soil
C)just below the highest piece of sandstone seen in the soil
D)just above the lowest piece of sandstone seen in the soil

Question 50

Which one of the following operates primarily in areas of permafrost?

A)rockslide
B)solifluction
C)slump
D)debris flow

Question 51

A ________ occurs where slopes are water saturated above permafrost.

A)slump
B)rock fall
C)solifluction lobe
D)debris flow

Question 52

Solifluction occurs wherever ________ sit upon ________ that will not allow excess water to drain away to deeper levels.

A)glaciers, frozen soils
B)loose soil, volcanic ash
C)talus cones, well jointed bedrock
D)water-saturated soils, dense clay hardpan or impermeable bedrock or permafrost

Question 53

Sometimes mass wasting triggered by major earthquakes is more destructive to property than the primary earthquake shaking itself.

Question 54

Oversteepening produces unstable slopes and mass movements in cohesive soils, regolith, and bedrock.

Question 55

Slump describes the very slow, downhill movement of soil and regolith.

Question 56

How does human activity not induce thawing of permafrost in the Arctic?

A)travelling on and removing tundra vegetation
B)building roads and railways
C)constructing buildings directly on the ground
D)flying over permafrost areas

Question 57

Frost action will make a slope less stable.

Question 58

Water saturation of soil on a slope reduces cohesion of soil particles and reduces slope stability.

Question 59

Which of the following contains ice wedges?

A)patterned ground
B)felsenmeer
C)thermokarst
D)pingo

Question 60

When and where is solifluction common?

A)rainy season in the tropics
B)monsoon season in India
C)dry season in grasslands south of the Sahara Desert
D)summer in polar regions

Question 61

Construction is most difficult in the discontinuous permafrost zone (> 54° N)because soil properties vary laterally and are hard to predict.

Question 62

Lahars are basically debris flows associated with steep volcanic valleys and unconsolidated volcanic deposits.

Question 63

Earthflows are often located downslope from slumps and triggered by the outflow of water from the slumps.

Question 64

Solifluction is an important mass wasting process in areas of permafrost.

Question 65

Solifluction occurs during the warmer summer months.

Question 66

Rockslides (dangerous, fast-moving masses of broken rock)are typically initiated by an earthquake.

Question 67

A scarp is the exposed portion of the rupture surface beneath a slump block.

Question 68

Felsenmeer is formed by melting permafrost and the expansion of talik.

Question 69

The 1811 mid-continent earthquake at New Madrid, Missouri caused 13,000 slides that dammed the Mississippi River for several weeks.

Question 70

Repeated freezing and thawing can be important in soil creep movements.

Question 71

Bedding planes and fractures can both act as slip surfaces for rockslides.

Question 72

Earthflows and slumps generally involve movement of unconsolidated or weakly consolidated soil and regolith.

Question 73

Slumps do not occur in river banks or eroding sea cliffs.

Question 74

Among the human factors which may have prepared or triggered the 1903 Frank Slide were deforestation on, and coal mining beneath, the slope that failed.

Question 75

Palsas are periglacial mounds of peat with lenses of ice.

Question 76

Volumetrically, the most important form of mast wasting is creep.

Question 77

Solifluction occurs below the active layer of permafrost.

Question 78

North of 60° N latitude the permafrost is virtually continuous whereas farther south to about 54° N it is discontinuous and very hard to predict its exact location.

Question 79

Thermokarst topography is produced by hot springs dissolving limestone terrain.

Question 80

Slumps can occur on oversteepened slopes or by overloading.