MASS WASTING Flashcards
The processes by which rock, soil, or unconsolidated materials move downhill under the influence of gravity are called
mass wasting
What is the dominant force that causes mass movement?
GRAVITY
Which of the following is not an important factor in causing mass movements?
A. temperature of slope materials
B. nature of slope materials
C. amount of water in materials
D. steepness and instability of slopes
A. temperature of slope materials
A hill consisting of loose, dry sand that slopes at the angle of repose and has no vegetation ______.
A. is stable unless oversteepened by excavation
B. may flow if it becomes saturated with water
C. will be more stable if vegetation takes root on the hill
D. all of these
D. all of these
Angular pebbles form steeper slopes than coarse sand
TRUE
The angle of repose does not depend upon
particle composition
situations is most likely to undergo mass wasting?
A. a dry, moderate slope of unconsolidated material
B. a wet, moderate slope of unconsolidated material
C. a dry, steep slope of unconsolidated material
D. a wet, steep slope of unconsolidated material
D. a wet, steep slope of unconsolidated material
As the amount of water in a pile of quartz sand increases, the angle of repose will
first increase and then decrease
The accumulation of rocks at the base of a cliff is called
TALUS
Solifluction occurs in
cold regions
Which of the following mass movements is the fastest?
debris avalanche
A slow slide of unconsolidated material that travels as a unit is called
SLUMP
The most important stress opposing a slope’s shear stress is imparted by:
gravity
Water can encourage mass flow by:
reducing friction between grains
undercutting a steep slope
weathering bedrock to clay minerals
A talus cone is produced by a:
ROCK SLIDE
Loose, uncemented geologic material is said to be
unconsolidated
most important factor in causing mass movements?
water content
The process by which masses of rock and soil move downhill under the influence of gravity is called
mass wasting
One of the most effective ways to stabilize a slope is to
control and remove water
The characteristic slope of a pile of dry sand is called the
ANGLE OF REPOSE
Damp sand has a higher angle of repose than dry sand because of
surface tension
Surface tension is greatest when
sand is moist, but not saturated with water
During an earthquake, water-saturated sand can behave like a liquid, a process called
liquefaction
Which of the following statements about mudflows is false?
mudflows tend to move slower than debris flows
mudflows are most common in semi-arid regions
mudflows contain large amounts of water
mudflows can carry large boulders
mudflows tend to move slower than debris flows
round debris forms steeper slopes than angular debris
FALSE
large debris forms steeper slopes than small debris
TRUE
dry debris forms steeper slopes than water-saturated debris
TRUE
moist debris forms steeper slopes than dry debris
TRUE
Which of the following has the steepest angle of repose?
angular quartz pebbles
rock types forms the steepest slopes?
granite
Which of the following slopes is least stable?
a slope where the sedimentary layers dip
parallel to the slope
a slope where the sedimentary layers are horizontal
a slope where the sedimentary layers dip perpendicular to the slope
all of these slopes have the same stability
a slope where the sedimentary layers dip parallel to the slope
Most of the damage associated with the 1964 Anchorage, Alaska earthquake was caused by
landslides triggered by the earthquake
In the cross section above of the upper part of the Grand Canyon, units B and D are most likely composed of
SHALE
What is the difference between an earthflow and a debris flow?
Earthflows travel faster than a debris flow
Earthflows travel slower than a debris flow
Earthflows consist of finer material than debris flows
Earthflows consist of coarser material than debris flows
Earthflows consist of finer material than debris flows
How fast is soil creep?
a1 to 10 millimeters per year
1 to 10 meters per year
1 kilometer per hour
over 10 kilometers per hour
a1 to 10 millimeters per year
Which of the following types of mass movement could a person not outrun?
debris avalanche
Why are mudflows and debris avalanches common on volcanic slopes?
because there is abundant unconsolidated volcanic ash
because earthquakes associated with volcanic
eruptions can trigger mass movements
volcanic eruptions trigger melting of ice and snow
all of these
all of these
Solifluction may occur when ________..
the surface layer freezes while the deeper soil remains unfrozen
the surface soil layer thaws while the deeper soil remains frozen
rapid downhill movement of unconsolidated material moving as unit
rapid downhill movement of unconsolidated material moving like a fluid
the surface soil layer thaws while the deeper soil remains frozen
only occurs in permafrost regions.
SOLIFLUCTION
Why are few mass movement preserved in the geologic record?
mass movements have only occurred recently due to human activities
mass movement deposits erode easily
mass movements were rare in the past due to low rainfall
mas movement deposits are destroyed by large animals
mass movement deposits erode easily
Mass movements frequently occur at which of the following plate tectonic settings?
convergent
divergent
transform
all of the above
all of the above
