Deck 10: Mass Wasting

Question 1

How does gravity affect a slope?

Answer 1

Gravity has a component that operates parallel to the slope,causing instability.Steeper slopes have a greater component of force in that direction,and so a greater chance of mass wasting.

Question 2

What are some ways by which a slope can become oversteepened? How can oversteeping cause mass wasting?

Answer 2

Slopes are oversteepened by undercutting by streams or waves,or excavations by human activities at their base.When the slope's base is removed,the slope angle increases,and the gravitational force acting parallel to the slope increases as well.

Question 3

In what ways are slope-stability maps useful to planners and developers?

Answer 3

Slope-stability maps are used to determine where certain types of buildings and other structures should or should not be built,and to indicate how slope stability might be improved,if structures are built where stability is compromised.

Question 4

Why is the California coastline so susceptible to losses due to mass wasting? Put together what you've learned so far for the answer.

Question 5

Briefly explain why saturated clay is a very unstable slope material.

Question 6

How would reducing the slope of a hillside help to stabilize it? What two methods can be used to reduce a slope's angle?

Question 7

What is shear strength? What factors collectively define a slope's shear strength?

Question 8

What role does weathering play in mass wasting?

Question 9

How does the geology (dip of rock layers or joints)on a slope affect slope stability?

Question 10

What factors played a role in the tragic rock slide at Frank,Alberta,Canada,in 1903?

Question 11

What is the effect of reducing water on a slope to mass movements? How can this be done?

Question 12

How does vegetation affect slope stability? What happens if vegetation is removed from the slope?

Question 13

What is the angle of repose for a slope? What forces are acting? What numerical value does this angle have?

Question 14

Compare and contrast rapid mass movements and slow mass movements.

Question 15

What factors contribute to mass wasting in tropical versus arid and semiarid climates?

Question 16

What is permafrost,and what problems are associated with construction in a permafrost environment?

Question 17

What are quick clays,and how do they cause damage?

Question 18

Compare and contrast mudflows,debris flows,and earthflows.

Question 19

Why is there sometimes wire mesh covering a steep slope? What are the characteristics of the type of mass wasting this is meant to prevent?

Question 20

How can areas with high potential for slope failure be identified?

Question 21

What is a slope-stability map?

Question 22

What human activities contribute to or cause mass wasting?

Question 23

How can slow mass movements be detected?

Question 24

What types of changes in a slope can lead to mass wasting?

Question 25

How does weathering promote mass wasting?

Question 26

What geologic conditions are usually present in the areas where most block slides occur?

Question 27

How does a slump differ from a rock slide?

Question 28

How does water content affect mass wasting?

Question 29

Give an example of a way in which mass wasting can affect human activity.

Question 30

If you were surveying hillside property on which you planned to build a home,what is some of the evidence of former mass wasting you would look for?

Question 31

How does a mudflow differ from a debris flow?

Question 32

What is the most important step that can be taken to minimize or eliminate mass wasting or damage from it?

Question 33

Because water can be so important in mass movement,what is one of the most effective and inexpensive ways of reducing mass wastage risk and damage?

Question 34

How can overloading affect slope stability?

Question 35

How can vegetation affect the likelihood of mass wasting?

Question 36

What methods can be used to stabilize a hillside?

Question 37

What is mass wasting?

Question 38

What is meant by the term "flow" when used with reference to mass movements?

Question 39

What climatic conditions are most conducive to solifluction?

Question 40

On the basis of what three criteria are mass movements classified?

Question 41

Creep is most effective and significant in a(n)____________________ climate.

Question 42

Movement that is made of more than one type of mass wasting,each of which are more or less equally involved,is called ____________________ movement.

Question 43

Clays that spontaneously liquefy and flow like water are called ____________________ clays.

Question 44

In the ____________________ and ____________________ method of protecting slopes,material is removed from the top of the slope and used as fill at the base.

Question 45

Additional weight added to a hillside,which is always the result of human activities,is called ____________________.

Question 46

Geologists call the downslope movement of material under the direct influence of gravity ____________________.

Question 47

Mass movements in which material flows as a viscous fluid or displays plastic movement are termed ____________________.

Question 48

In the ____________________ method of protecting slopes,steps are cut into a hillside to reduce the overall average slope and catch small landslides or rockfalls.

Question 49

Mass movements in which rocks fall through the air are known as ____________________.

Question 50

A type of mass wasting that forms quickly,moves rapidly,and transports both small and very large objects and can be very dangerous is ____________________.

Question 51

The material accumulated at the base of cliffs where rocks fall is known as ____________________.

Question 52

All slopes are constantly adjusting to new conditions,which means they are in a state of ____________________.

Question 53

Ground that remains permanently frozen is called ____________________.

Question 54

The fundamental cause of mass wasting is ____________________.

Question 55

____________________ can be constructed to provide support to the base of a slope.They are anchored into bedrock,backfilled with crushed rock,and provided with drain holes to prevent buildup of water pressure in the hillside.

Question 56

A rapid downslope mass movement of snow and ice is called a(n)____________________.

Question 57

The downward movement of material along a curved surface of rupture,which is characterized by the backward rotation of the displaced block,is called a(n)____________________.

Question 58

The downslope movement of water-saturated surface sediment is called ____________________.

Question 59

Curved tree trunks,displaced monuments,tilted power poles,displaced and tilted fences,roadways moved out of alignment,and hummocky surfaces are all evidence of ____________________.

Question 60

A general term for mass movements of earth is ____________________.

Question 61

The removal of vegetation is a significant cause of slope failure and mass wasting.

Question 62

A rainstorm can trigger the landslide of an unstable slope.

Question 63

Mass movement that occurs along a curved surface of a rupture is known as:

A)rockfall.
B)slide.
C)creep.
D)slump.
E)none of these

Question 64

The type of mass wasting that is responsible for the greatest amount of monetary damage is:

A)creep.
B)slumps.
C)rockfall.
D)slides.
E)avalanches.

Question 65

All other factors being equal,the chance of mass wasting is increased by:

A)the amount of material involved.
B)the lack of friction on the slope.
C)the angle of the slope.
D)the kind of event that initiates the mass wasting.
E)whether there exists a positive or negative gravity anomaly.

Question 66

The most common triggering mechanism for mass wasting is:

A)vibrations due to earthquakes.
B)a sudden influx of excessive water.
C)erosion of the slope base.
D)vibrations due to earthquake and a sudden influx of excessive water.
E)vibrations due to earthquakes,a sudden influx of excessive water,and erosion of the slope base.

Question 67

Most mass wasting is enhanced or promoted by:

A)erosion.
B)weathering.
C)flash floods.
D)wind erosion.
E)plate tectonics.

Question 68

Creep occurs only on weathered or soil-covered surfaces of moderate slope.

Question 69

The type of mass movement that moves the greatest amount of material downslope is:

A)creep.
B)slumps.
C)rockfall.
D)slides.
E)avalanches.

Question 70

The slow downslope movement of water-saturated surface sediment is:

A)quick clay.
B)solifluction.
C)creep.
D)slump.
E)earthflow.

Question 71

Mass wasting does not occur on:

A)unstable material.
B)near-level slopes.
C)steep slopes.
D)gradual slopes.
E)It occurs on all of these.

Question 72

Overloading of a slope is rarely the fault of human action.

Question 73

Mudflows are particularly common in climates that are:

A)humid and warm.
B)temperate.
C)arid to semiarid
D)cool.
E)very rainy.

Question 74

Some mass wasting occurs at almost imperceptibly slow rates.

Question 75

After gravity,the major cause of mass wasting is:

A)slope angle.
B)weakening by weathering.
C)overloading.
D)vegetation loss.
E)increased water content.

Question 76

Mass wasting is more likely to occur in:

A)deeply weathered material.
B)thin layers of loose material.
C)bedrock.
D)well sorted material.
E)material of large grain size.

Question 77

Mass wasting is most likely to occur in:

A)arid warm regions.
B)humid tropical regions.
C)arctic regions.
D)temperate regions.
E)none of the above

Question 78

Permafrost lies beneath ____% of the land surface on Earth.

A)0
B)10
C)20
D)40
E)50

Question 79

Most major landslides:

A)are caused by earthquakes.
B)are caused by volcanic eruptions.
C)have natural causes.
D)are due to human activity and poor engineering.
E)none of the these

Question 80

Among the types of slides are:

A)slumps.
B)block slides.
C)mudflows.
D)slumps and block slides.
E)slumps,block slides,and mudflows.