Deck 15: Weathering, soil, and Unstable Slopes

Question 1

Some rocks and minerals are not stable at the surface because they:

A)are exposed to water
B)formed in high-temperature environments
C)formed in high-pressure environments
D)are exposed to oxygen
E)all of these

Answer 1

E

Question 2

The joints in the photograph mimic topography,indicating that they formed:

A)while the granite was still molten
B)while the rocks were still buried at great depth
C)when the weight of overlying rocks was unloaded,allowing expansion along the joints
D)along a subduction zone

Answer 2

C

Question 3

Joints in the landscape:

A)mostly form at depth and are uplifted to the surface
B)can detach thin slices of rock parallel to the land surface
C)cause highly jointed areas to be less resistant to weathering than more jointed ones
D)all of these

Answer 3

D

Question 4

What should have warned the people of coastal Venezuela that they were in a hazardous zone?

A)the cities were built upon alluvial fans
B)the houses had been built on debris flow deposits
C)the areas above the city had steep unstable slopes
D)all of these

Question 5

What is a common rock that can be dissolved by water and weak acids?

A)quartzite
B)quartz-rich sandstone
C)limestone
D)all of these

Question 6

What events caused so much damage along the north coast of Venezuela in 1999?

A)a landslide shook loose a large piece of the mountains that caused the water in the reservoir to flood local towns
B)torrential rains caused debris flows and flash floods that raced through cities
C)the slow movement of slopes downhill broke apart houses but did not kill any people
D)overgrazing caused a loss of grass cover and resulted in severe soil erosion

Question 7

What concepts can be explained using this diagram?

A)the movement of water between the oceans and the land
B)how precipitation ends up in rivers or groundwater
C)how weathering causes the seas to become saltier
D)all of these

Question 8

What happens to the surface area of exposed rock if a rock is fractured?

A)there are more pieces,but the surface area does not change
B)the surface area does not change because the volume does not change
C)the surface area increases as the rock is fractured
D)the surface area decreases as the rock is fractured

Question 9

Which of the following factors control how minerals weather?

A)whether the mineral has ionic or covalent bonds
B)what type of mineral is present
C)the temperature at which the original minerals formed
D)whether a mineral typically crystallizes early or late in Bowen's Reaction Series
E)all of these

Question 10

The layer of quartzite in this photograph would mostly weather by:

A)dissolution
B)hydrolysis
C)physical weathering
D)spontaneous combustion

Question 11

What is the main reason why the oceans are salty?

A)the early oceans were salty because comets are dirty snowballs
B)salt deposits that formed early in Earth's history become dissolved by modern oceans
C)weathering of rocks releases chemical elements that make the oceans salty
D)blowing salt crystals become incorporated into clouds and falls with the rainfall

Question 12

Which of the following does NOT commonly occur when dark-colored mafic rocks weather?

A)mafic minerals weather to clay minerals by hydrolysis
B)iron-bearing minerals can oxidize to form the iron oxide mineral hematite
C)the abundant quartz in the rocks dissolves and forms silica-rich spring deposits
D)some minerals weather at different rate than other minerals

Question 13

Where does the quartz in granite typically end up?

A)as small clay minerals that are deposited in lakes and the sea
B)quartz does not weather and so it keeps the granite from weathering
C)it ends up as sand in rivers,dunes,and beaches
D)it is converted into feldspar and weathers into clays

Question 14

What is the dominant type of weathering is shown in this photograph?

A)dissolution
B)chemical weathering
C)debris flow
D)hydrolysis
E)physical weathering

Question 15

Which of the following does NOT physically loosen rocks on the surface?

A)water contracting as it freezes
B)crystals of salt and other minerals that exert an outward force on fractures
C)roots that pry apart fractures as the root grows in size
D)joints that form when rock pressures are released
E)rodents and other burrowing organisms

Question 16

What happens when rocks oxidize near Earth's surface?

A)minerals in the rock release oxygen that can break down adjacent rocks
B)oxygen combines with water to create weak acids that weather rocks
C)minerals,especially those with iron,combine with oxygen
D)oxygen combines with silica to make quartz

Question 17

Which of the following is valid for how rocks weather?

A)quartz is very soluble during weathering at low temperatures
B)limestone weathers rapidly in wet climates but can form cliffs in dry ones
C)as a granite weathers,quartz rapidly decomposes into clay minerals
D)most minerals in granite weather at nearly the same rate and so granite has smooth surfaces

Question 18

What is the main type of weathering illustrated by this weathered limestone?

A)physical weathering
B)dissolution
C)oxidation
D)exfoliation

Question 19

How does the character of a rock influence weathering

A)Fractures and other discontinuities block the entry of water into a rock and so make the rock more resistant to weathering.
B)Minerals that are soluble can be dissolved and reprecipitated and so are resistant to weathering.
C)Rocks that are broken have more surface area and so weather faster.
D)Rocks that are easily weathered and eroded generally form steep cliffs.
E)None of these.

Question 20

Why does weathering of granite bedrock produce rounded shapes?

A)the rounded shapes are pillows formed at depth in the granitic magma
B)weathering removes corners and edges,as in spheroidal weathering
C)burrowing animals eat away parts of the granite
D)roots rub against the edges of the granite

Question 21

A soil that has little or no O-horizon but a thick accumulation of calcium carbonate (caliche)most likely forms in:

A)a tropical climate
B)a temperate climate
C)an arid climate
D)an area with abundant rainfall
E)a short amount of time

Question 22

Which of the following is NOT a common trigger for slope failure?

A)adding water to a slope
B)volcanic eruption
C)shaking during an earthquake
D)oversteepening of cliffs or hillslopes during road construction
E)all of these are common triggers for slope failure

Question 23

Which of the following is true about how weathering affects fractured rocks?

A)weathering affects rocks from the outside in,forming an outer weathered zone or rind
B)weathering attacks corners from three sides and so these are preferentially removed
C)preferential weathering along fractures can cause blocks to become rounded
D)all of these

Question 24

Which of the following is NOT a source of material for soil?

A)weathered rock and sediment
B)leaves and other plant debris
C)CO₂ gas from roots
D)water from precipitation and snowmelt
E)all of these are a source of material in soil

Question 25

Which of the following are problems related to soil?

A)individual grains lose contact with one another as water squeezes between them
B)certain clay minerals increase in volume when they become wet
C)soils that do not compact uniformly because of varying amounts of clay
D)erosion due to loss of plant cover,such as from overgrazing
E)all of these

Question 26

Which of the following is an expression of the angle of repose?

A)talus slope
B)some slopes of sand dunes
C)angle of slopes on scoria cones
D)all of these

Question 27

Which of the numbered soil horizons is most likely to have clay or calcium carbonate?

A)1
B)2
C)3
D)4
E)5

Question 28

How does material in soil move?

A)the upper part of soil loses material downward
B)clay minerals and other fine particles are carried downward
C)chemical ions leached from above can accumulate in the underlying zone
D)calcium carbonate can accumulate in the soil,especially in dry environments
E)all of these

Question 29

People reshape steep slopes,a practice called terracing,in order to:

A)help capture and retain rainfall
B)provide a level place on which to farm
C)promote soil formation
D)protect soil from erosion
E)all of these

Question 30

The main feature shown in this photograph illustrates:

A)weathering
B)flooding
C)permafrost
D)slope failure

Question 31

Which of the numbered soil horizons are most likely to represent an accumulation of organic debris?

A)1 and 2
B)2 and 3
C)3 and 4
D)4 and 5
E)all of these

Question 32

Which of the numbered soil horizons is most likely to have remnants of weathered bedrock?

A)1
B)2
C)3
D)4
E)5

Question 33

Soil that is reddish,intensely leached,and rich in iron and aluminum minerals most likely forms in:

A)tropical climate
B)temperate climate
C)arid climate
D)an area with only minor soil development
E)a short amount of time

Question 34

What is the angle of repose?

A)the angle of bedding on hills where layers dip parallel to the slope
B)the angle of fractures on hills where fractures dip parallel to the slope
C)the angle at which rainfall strikes an unstable slope
D)the steepest angle at which loose material remains stable

Question 35

What is the main force involved in the stability of slopes?

A)water pressure
B)sunlight
C)wind
D)gravity
E)radioactivity decay

Question 36

Which of the following factors does NOT control the stability of a slope?

A)the angle of repose for intact bedrock
B)whether the slope is rock or soil
C)the amount of water in the soil
D)the orientation of fractures,cleavage,and bedding

Question 37

As illustrated in this figure,which of the following is NOT potential trigger for slope failure?

A)precipitation that can saturate and weaken sediment
B)undercutting of steep slopes by roads and rivers
C)shaking during an earthquake
D)shaking of slopes and melting of snow during volcanic eruptions
E)all of these are illustrated

Question 38

What is the main process by which soils form?

A)deposition of silt on a floodplain
B)deposition of silt by the wind
C)weathering
D)erosion

Question 39

Which of the following are true about factors that influence weathering?

A)Chemical weathering occurs fastest in cold or dry climates.
B)Whether a slope faces toward or away from the sun is not an important factor influencing weathering.
C)Soil and other weathering products tend to accumulate more on gentle slopes than on steep slopes.
D)Time is not a critical factor in weathering because physical and chemical processes have not changed much through time.

Question 40

How can weathering form a mineral deposit?

A)extreme leaching can leave behind elements,such as aluminum,that are valuable
B)weathering can dissolve copper from the top of a mineral deposit and reprecipitate it at depth
C)heavier materials,such as gold and diamond,accumulate near the base of river gravels
D)all of these

Question 41

Which of the following is a way that slopes fail?

A)large blocks fall from cliffs
B)rocks,soil,sediment,and ice slides down steep hillsides
C)pieces of loose rock accumulate on talus slopes until the angle becomes too steep
D)soil and other loose material can flow rapidly down slopes,forming debris flows
E)all of these

Question 42

The main feature shown in this photograph illustrates?

A)weathering
B)flooding
C)permafrost
D)slope failure

Question 43

What type of slope failure is shown in this figure?

A)rotational slide
B)creep
C)debris slide
D)debris flow
E)rock fall

Question 44

What factors lead to the Viaont landslide disaster?

A)a volcanic eruption shook the ground
B)a major earthquake shook the ground
C)the sedimentary layers dipped downslope toward the reservoir
D)all of these

Question 45

Which of the following slope failures moves at the slowest rate?

A)earth flow
B)rock avalanche
C)debris flow
D)rock fall
E)debris avalanche

Question 46

The type of slope failure shown in this photograph is:

A)creep
B)a rock slide
C)a debris avalanche
D)a debris flow
E)all of these

Question 47

What type of slope failure is shown in this figure?

A)rotational slide
B)creep
C)rock avalanche
D)debris flow
E)rock fall

Question 48

Which of the following factors is typically NOT used to classify slope failures?

A)whether the material involved is rock or is unconsolidated
B)the rate of movement
C)the climate in which the failure occurs
D)the mechanism by which material moves

Question 49

Which of the following slope failures is least likely to cause casualties?

A)rock avalanche
B)debris flow
C)creep
D)rock slide
E)rock fall

Question 50

Which numbered feature on this figure is critical to enable a rock slide to start?

A)1,a linear or curved scar marking where the slide pulled away from the hill
B)2,small fractures within the sliding block
C)3,layers,fractures,or some other discontinuity inclined downslope
D)4,the front of the slide,where it overruns the land surface
E)5,a valley or other open space in front of the slide

Question 51

What type of slope failure is shown in this figure?

A)debris avalanche
B)creep
C)rock slide
D)debris flow
E)rock fall

Question 52

Which numbered feature on this figure is a scarp?

A)1,a linear or curved scar marking where the slide pulled away from the hill
B)2,small fractures within the sliding block
C)3,the intact layers below the rock slide
D)4,the front of the slide,where it overruns the land surface
E)5,a valley or other open space in front of the slide

Question 53

What type of slope failure is depicted in this photograph?

A)creep
B)rock fall
C)debris avalanche
D)permafrost

Question 54

What type of slope failure is shown in this figure?

A)creep
B)debris flow
C)rock fall
D)rock slide
E)rotational slide

Question 55

What type of slope failure is shown in this figure?

A)rotational slide
B)creep
C)earth flow
D)debris flow
E)rock fall

Question 56

Which of the following slope failures is most likely to cause large numbers of casualties?

A)creep
B)debris slide
C)earth flow
D)rotational slide
E)rock avalanche

Question 57

What type of slope failure is shown in this figure?

A)rotational slide
B)creep
C)earth flow
D)debris flow
E)rock slide

Question 58

What type of slope failure is shown in this figure?

A)rotational slide
B)creep
C)earth flow
D)debris flow
E)rock avalanche

Question 59

Which of the following has the lowest potential for landslides?

A)Pacific Northwest
B)southern California
C)bluffs along rivers in the central U.S.
D)Florida
E)Appalachian Mountains

Question 60

Which of the following factors favors movement of a rock slide?

A)layers that are inclined opposite to the slope of the hill
B)solid rock with few preexisting joints or faults
C)a massive rock with no bedding or other through-going discontinuities
D)a valley or other open space downslope from the rock slide

Question 61

The USGS evaluated the age of different parts of the Slumgullion feature by:

A)measuring the size of trees incorporated into the material
B)measuring the temperature of rocks soon after the feature had moved
C)examining the development of soil
D)measuring the content of moisture during different seasons
E)none of these

Question 62

Which area would most likely cause the least problems with keeping roads in good shape?

A)Bent Fence Hills
B)Wild Ride Valley
C)the flat area above the river terraces
D)a road built directly below the cliffs of Flattop Mountain

Question 63

What did the USGS discover when they studied the Slumgullion feature?

A)there were different parts with different ages
B)movement formed folds,faults,fissures,and zones of shearing
C)some parts of the material moved faster than other parts
D)all of these
E)a and b only

Question 64

What type of slope failure has occurred in the Slumgullion area of Colorado?

A)a huge rock fall that formed Colorado's second largest lake
B)a debris flow that came down Big Thompson Canyon
C)a debris avalanche that raced downhill at breathtaking speeds
D)a slow-moving earth flow

Question 65

Which of the following can we use to recognize prehistoric slope failures?

A)sedimentary deposits
B)orientation of beds and other geologic structures
C)masses of rock fragments that are unusual for an area
D)hummocky topography
E)all of these

Question 66

Which of the following areas in the investigation terrain is least likely to cause casualties in the event of a slope failure?

A)Bent Fence Hills with the leaning trees
B)flanks of Flattop Hill
C)Rock Valley
D)the area below Tilted Mountain

Question 67

Which of the following is the main hazard for areas along the river terrace?

A)shrinking and swelling of clays
B)slow movement of material downslope
C)rock falls
D)debris flows that carry large blocks from the volcano

Question 68

Based on the photographs of La Conchita,California,what type of slope failure occurred?

A)rock avalanche
B)debris flow
C)creep
D)rock fall
E)earth flow

Question 69

The landslide that destroyed La Conchita,as shown in this photograph,is probably:

A)an example of creep
B)an earth flow
C)a rock fall
D)a rock avalanche

Question 70

Which of the following factors caused some high peaks of the Cascade Mountains of the Pacific Northwest to have high potential for slope failure?

A)they are volcanoes with steep slopes
B)they experience heavy rainfall
C)they may contain loose volcanic ash and other volcanic materials
D)all of these

Question 71

Which of the following might indicate that slopes adjacent to this landslide might fail?

A)they have the same steepness as the slope that failed
B)they appear to have a similar geology setting
C)one part of the slope has already failed
D)all of these

Question 72

Which of the following is probably NOT important in assessing an area's potential for slope failure?

A)comparing the geologic setting to adjacent areas that have or have not failed
B)whether the material is loose sediment or solid bedrock
C)recent changes in slope
D)the orientation of layering and fractures
E)all of these are important