Deck 8: Weathering, Soil, and Mass Movement

Question 1

What is the major distinction between internal and external Earth processes?

A) Internal and external processes can occur inside and outside Earth, but external processes must also include the oxidation of Earth materials.
B) Internal processes are driven by processes like plate tectonics, and external processes are driven by the Sun.
C) Internal processes involve heat while external processes involve oxygen.
D) Internal processes can only occur inside the Earth, but external processes can occur inside or outside Earth.

Answer 1

Internal processes are driven by processes like plate tectonics, and external processes are driven by the Sun.

Question 2

Centuries ago quarrymen learned that when quarrying granite it was usually easiest to break the rock along a nearly horizontal surface. We now know this arises because ______.

A) chemical weathering of granite makes the material expand, pulling it away from the underlying rock
B) uplift and exhumation of granites produces an unloading, which produces sheeting joints like the quarrymen used
C) frost wedging for hundreds of thousands to millions of years have produced cracks parallel to the ground surface
D) it was a false observation; the quarrymen in those days couldn't measure resistance, and it just seemed easier to wedge blocks of this type

Answer 2

uplift and exhumation of granites produces an unloading, which produces sheeting joints like the quarrymen used

Question 3

Frost wedging is the major weathering process contributing to the formation of which regolith material?

A) clay minerals
B) talus slopes
C) soil horizons
D) tropical soils

Answer 3

talus slopes

Question 4

Which one of the following statements best describes erosion?

A) disintegration and decomposition of rocks and minerals at the surface
B) movement of weathered rock and regolith toward the base of a slope
C) the combined processes of leaching, eluviation, and mass wasting
D) the process by which weathered rock and mineral particles are removed from one area and transported elsewhere

Question 5

Below is an image of two tombstones that were both emplaced in 1863. Why would the left tombstone be so much better preserved than the right tombstone? Select the best answer.

A) Two tombstones may be in the same location and be of the same rock type, but one just happened to weather faster than the other.
B) The two tombstones may be made of different rock types, and thus rates of weathering would differ.
C) The two tombstones may be located in different locations and thus have different climates.
D) It is possible that they are both in different climates and are made of different rock types.

Question 6

Chemical weathering rates are highest in ______ .

A) cold wet climates
B) cold dry climates
C) hot dry climates
D) hot wet climates

Question 7

Under similar warm, moist climatic conditions, why would basalt and gabbro generally have higher chemical weathering rates than rhyolite and granite?

A) The plagioclase feldspars in the granite and rhyolite decompose readily to clay minerals and iron oxides.
B) The potassium feldspars and quartz in the rhyolite and granite are more susceptible to cracking by frost wedging.
C) The ferromagnesian minerals in the gabbro and basalt are subject to oxidation and chemical breakdown.
D) The quartz in the gabbro and basalt decomposes very quickly.

Question 8

Which of the following is not a physical weathering process?

A) tree root growth
B) frost wedging
C) salt crystallization
D) rocks reacting with organic acids from plants

Question 9

Which of the following best describes sets of fractures in relatively fresh bedrock, such as granite, that are roughly parallel to the land surface?

A) hydrolytic failures
B) columnar joints
C) thermal expansion cracks
D) sheeting fractures

Question 10

Mass wasting, a process that often occurs between weathering and erosion, involves ______.

A) the mechanical breakdown of minerals due to exposure to the Sun and atmosphere
B) the transport of material by water, wind, or ice
C) the transport of material due to gravity
D) the chemical dissolution of minerals due to water

Question 11

Rounding of angular edges of rock outcropping and formation of in situ, spherical boulders are both indications of ______ .

A) dissolution of the rock surface by acid rain
B) humans and animals walking across the Earth's surface, wearing away the surface
C) chemical weathering and associated spheroidal weathering
D) rock fall onto sharp edges breaking of angular corners of rock outcrops

Question 12

Assume that water filling a crack in a rock undergoes cycles of freezing and melting. Which of the following statement is true?

A) Water shrinks as it freezes, causing the crack walls to be drawn closer together.
B) Water expands as it melts, causing the crack walls to be pushed apart.
C) Water expands as it freezes, causing the crack walls to be pushed apart.
D) Water shrinks as it melts, causing the crack walls to be pulled closer together.

Question 13

Clay minerals formed from gabbro or diorite bedrock illustrate which kind of weathering?

A) mechanical
B) chemical
C) syntropical
D) proactive

Question 14

Which one of the following is an important, mechanical weathering process for enlarging fractures and extending them deeper into large boulders and bedrock?

A) eluviation
B) oxidation
C) frost wedging
D) hydrologic cycling

Question 15

Red, brown, and yellow soil- coloring minerals originate by what process?

A) mechanical weathering of very fine- grained, blue- gray clays
B) precipitation of iron oxides from chemical weathering
C) chemical weathering of quartz and feldspars
D) mechanical weathering of the feldspars and micas in granite and rhyolite

Question 16

Which of the following is most resistant to both chemical and physical weathering?

A) limestone
B) clay minerals
C) quartz
D) granite

Question 17

Which one of the following statements concerning mechanical weathering is not true?

A) is important in the formation of talus slopes
B) allows for faster rates of chemical weathering
C) reduces grain sizes of rock particles
D) involves a major change in the mineral composition of the weathered material

Question 18

All of the following are factors that affect rates of weathering except for______ .

A) geologic age of Earth materials
B) climate
C) rock characteristics
D) surface area

Question 19

What two factors speed up rates of chemical reaction and weathering in rocks and soils?

A) warm temperatures; very moist
B) high temperatures; very dry
C) low temperatures; very moist
D) low temperatures; very dry

Question 20

One important relationship between chemical and mechanical weathering is______ .

A) mechanical weathering forms more brittle materials that are easily broken down by chemical weathering
B) mechanical weathering can produce smaller pieces of rock that have more surface area for chemical weathering to work on
C) chemical weathering can produce smaller pieces of rock that can then be modified by mechanical weathering
D) chemical weathering can form brittle materials that are easily broken into smaller pieces by mechanical weathering

Question 21

Which term describes a soil formed by weathering of the underlying bedrock?

A) transformational
B) relict
C) residual
D) transported

Question 22

Features like rock ledges in badlands or rock fins standing above adjacent valleys are all examples of ______.

A) river erosion
B) glacial erosion
C) differential weathering
D) chemical weathering

Question 23

Engineers refer to any loose material on the surface of the Earth as soil. How does this differ from the definition Earth scientists prefer?

A) Earth scientists only use the word soil to refer to the inorganic part of weathered, surface materials.
B) There is no difference, the definition is the same.
C) Earth scientists use the term soil only for the organic part of the surface materials.
D) An engineer's "soil" is equivalent to what Earth scientists call regolith; but for Earth scientists soil has a more specific meaning.

Question 24

The longer a soil has been forming, the______ it becomes.

A) thicker
B) more fine grained
C) darker
D) less weathered

Question 25

Limestone and marble weather faster than granite because______ .

A) limestone and marble can be dissolved by weak acids in rain
B) granite is more resistant to physical weathering because of its large crystals
C) granite does not react with rainwater and only weathers by physical erosion
D) limestone has many cracks and holes that allow water to infiltrate and weather the rock

Question 26

Organisms contribute to soils formation by ______ .

A) stirring the soil to allow air infiltration
B) degrading organic matter to form humus
C) contributing organic matter to the soil
D) all of the above

Question 27

The weather conditions that least favor chemical weathering are ______ and ______,

A) warm; wet
B) cool; wet
C) warm; dry
D) cool; dry

Question 28

Which of the following best describes the process of eluviation?

A) removal of very fine- sized silt and clay particles from the A and E soil horizons
B) buildup of calcite in the B- horizon of pedocal soils
C) feldspar decomposition and leaching of the soluble products from the C soil horizon
D) removal of soluble chemical constituents from the A and B soil horizons

Question 29

Why is soil structure important to know?

A) It is an indicator of future climate.
B) It is an indicator of how susceptible the soil is to erosion.
C) It reveals composition.
D) It is not that critical; what matters is organic content.

Question 30

The word topsoil is commonly used, but not always correctly. The proper definition of topsoil is ______.

A) the entire soil down to the base of the C horizon
B) the dark, organic rich layers of O and A
C) the A, E and B horizons
D) only the O horizon

Question 31

A soil that has nearly equal amounts of clay, silt and sand is called______ .

A) loam
B) clayey
C) rich
D) lane

Question 32

Which of the following best describe the E soil horizon?

A) leaching zone
B) residual zone
C) erosion zone
D) regolith zone

Question 33

From the land surface downward to the unweathered bedrock, which of the following is the correct order of the different soil horizons?

A) D, E, C, B, A, bedrock
B) A, B, C, D, E, bedrock
C) E, A, B, C, O, bedrock
D) O, A, E, B, C, bedrock

Question 34

In the Rocky Mountain region of the United States, north- facing slopes downhill direction is toward the north. are typically moister and more heavily forested than south- facing slopes. Why?

A) North- facing slopes receive about the same amount of precipitation as south- facing slopes; less moisture evaporates from north- facing slopes.
B) South- facing slopes receive less moisture, yet rock weathering is faster.
C) South- facing slopes receive more moisture and sunlight; rock weathering is slower.
D) North- facing slopes receive more sunlight in the summer; snow melts faster and more soil moisture is available for the trees.

Question 35

Which type of soil would typically be the richest soil?

A) upland slope
B) residual
C) transported
D) desert

Question 36

In which area would weathering by frost wedging probably be most effective?

A) in cool high desert areas
B) where the subsoil is permanently frozen
C) in moist, temperate climates
D) in a moist, tropical forest

Question 37

Given enough time, what factor is typically most important in soil formation?

A) bedrock type
B) months of snow cover
C) slope direction
D) climate

Question 38

In much of what is now Canada, glaciers covered the land as little as 12,000 years ago and glacial erosion scoured the land surface leaving very thin soil or bare rock over large areas. The Midwestern United States was also covered in ice at this time, yet this area contains some of the richest farm land in the world with thick soils. These soils are formed on glacial sediments and windblown dust deposits from the ice age. Why are the soil conditions between these areas so different when the soils are virtually identical in age?

A) Sea level rose following the ice age and covered the Midwest with an inland sea, rapidly forming soil.
B) It is much colder in Canada so chemical weather is much slower; thus and soils have not had time to form.
C) The Midwestern soils are transported soils with soil development on materials that were already loose, unconsolidated materials.
D) The Midwestern U.S. is much flatter than Canada, allowing soils to develop more quickly.

Question 39

Digging downward through a soil profile, how deep would you have to go before you found recognizable fragments of the parent rock for the soil?

A) A
B) B
C) C
D) E

Question 40

Deep soils are characteristic of tropical regions whereas thin rocky soils are characteristic of high latitudes. This is a natural demonstration that______ .

A) humans living at high latitudes have destroyed the soils by bad farming practices
B) chemical wreathing rates are much higher in the tropics than high latitudes
C) physical weathering and erosion rates are higher at high latitude, removing soil faster than it can form
D) all of the high latitude regions lost their soil in recent times

Question 41

Which of the following is not a significant factor triggering mass wasting events?

A) mine tailings filling a valley
B) forest fire
C) heavy rainfall
D) earthquake

Question 42

Which soil horizon represents the lowest part of the zone of accumulation, also referred to as the subsoil?

A) soil
B) sol
C) solt
D) dirt

Question 43

A mass wasting process that involves slip of solid rock above a distinct sliding surface is called______ .

A) a slump
B) a rock avalanche
C) a rock fall
D) a rock slide

Question 44

Most insurance companies will not insure property with a known landslide hazard. Why?

A) They are known to always occur during major disasters like earthquakes and hurricanes, and they don't want the exposure to a large disaster.
B) The risk is negligible on human time spans, but they are unwilling to take the risk because of liability.
C) They are just being cheap.
D) The risk is high on human life time scales, and the hazard is difficult to assess.

Question 45

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 is not affected by the slope angle.
B) It will increase as the slope angle is lessened.
C) It will decrease as the slope angle is lessened.
D) It will possibly increase or decrease as slope angle is lessened, depending upon other factors.

Question 46

Deforestation of rain forests exposes tropical soils that are famous for their low fertility, despite the fact that they had previously hosted a lush tropical forest. Which soil type would describe these soils?

A) Andisols-young soils formed on volcanic ash and volcanogenic sediment.
B) Oxisols-Soils that occur on old land surfaces unless parent materials were strongly weathered before they were deposited. Rich in iron and aluminum oxides, Oxisols are heavily leached, hence are poor soils for agricultural activity.
C) Vertisols-Soils containing large amounts of clay, which shrink upon drying and swell with the addition of water. Found in subhumid to arid climates.
D) Histosols-Organic soils with little or no climatic implications. Can be found in any climate where organic debris can accumulate to form a bog soil. Dark, partially decomposed organic material commonly referred to as peat.

Question 47

After the drought of the 1930's farmers in the Great Plains were encouraged to plant rows of trees across fields to decrease soil erosion. How would this reduce soil erosion?

A) The trees helped shade the ground, retaining moisture.
B) Tree roots would retard runoff and prevent erosion.
C) The trees can serve as windbreaks to slow wind erosion.
D) The trees had no effect; they were just used to improve the land appearance after the great depression.

Question 48

As an erosional process, how is mass wasting unique compared to wind, water, and ice?

A) Mass wasting does not require a transporting medium.
B) Mass wasting affects particles of all sizes whereas the others affect only smaller particles.
C) Mass wasting affects much larger geographic areas than does wind, water, and ice.
D) All of the above make mass wasting unique compared to wind, water, and ice.

Question 49

What type of sand holds its shape the best?

A) wet sand
B) dry sand
C) saturated sand
D) moist sand

Question 50

Most stream valleys have a V shaped cross section because______ .

A) water washing down the slope makes straight channels
B) mass wasting of weathered rocks on the slope maintain an angle of repose slope
C) vegetation on the slopes forces this profile
D) none of the above

Question 51

You buy land in the tropics on steep mountain slopes covered by large trees and deep soil. You want to build a house on the land. Which of the following building plans is a not adviseable because of the danger of triggering mass wasting?

A) Terrace the slope, building on the terraces, and constructing a rock retaining well with voids to allow drainage of water.
B) Excavate the soil from the building site, install drainage systems, and backfill with gravel to prevent water accumulation.
C) Sell the land because it will always be prone to mass wasting.
D) Excavate a flat bench on the slope for the house, pushing the debris to the slope below and leave a cut bank above the flat bench with grass planted on the steep slope.

Question 52

In terrain with steep hill slopes, which crop and cultivation technique will minimize soil erosion?

A) apples; land between the trees is planted in grass and not cultivated
B) bean; rows are spaced wider than on a level field
C) winter wheat; after the harvest, the field is plowed and left idle until next fall
D) corn; rows trending straight down the slope, frequent cultivation

Question 53

Climate change and human activity like overgrazing of grasslands is leading to large areas subject to "desertification" where native grass cover dies out during drought periods, exposing soil to erosion. What is potentially the greatest initial soil erosion potential during this type of an event?

A) loss of topsoil by wind erosion on a large scale
B) local gullying produced by intermittent rain storms
C) growth of shrubs shading the ground, further killing the grasses
D) sand blown in from adjacent deserts

Question 54

In North America "no till farming" has become a widespread practice made possible by genetically modified GM. crops that can be sprayed with herbicide that kills everything but the GM plant. Evaluate the following statements on the role of GM crops on soil conservation issues?

A) They have no effect one way or the other on soil erosion.
B) The no till practice dramatically improves soil conservation by providing loose organic matter cover to the soil surface, breaking up wind and runoff, lowering erosion rates.
C) They are problematic because by killing all plants except the GM organism they expose the soil to increased erosion.
D) The herbicides kill beneficial plants and animals and eventually will make the soil sterile.

Question 55

A mass wasting process that involves rotational motion of material sliding above a distinct slip surface is called ______.

A) a slump
B) a rock avalanche
C) a rock fall
D) a rock slide

Question 56

Water runoff is a major factor in soil erosion, what is a common land use practice on slopes to minimize soil erosion?

A) planting row crops with rows running downhill, to minimize channelization of flow
B) planting trees
C) adding a rock mulch layer to slow water runoff
D) terracing slopes to stop downslope runoff and rill formation

Question 57

Which soil horizon represents the lowest part of the zone of accumulation, also referred to as the subsoil?

A) A
B) B
C) C
D) E

Question 58

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

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

Question 59

Landslides commonly occur when hurricanes hit steep terrain. Why?

A) The correlation with hurricanes is coincidental.
B) The high winds produce a shear stress on the slopes, triggering mass movements.
C) Heavy rain from the tropical system can saturate slopes, triggering mass wasting events like mudslides.
D) The high winds uproot trees, weakening the slope and inducing mass wasting.

Question 60

How does deforestation by fire or human activity contribute to mass wasting?

A) It allows the wind to blow across the slopes, imparting a stress that triggers landslides.
B) It kills tree roots that help hold the slopes in place, allowing mass movement.
C) It allows excess rainfall runoff to erode the landscape, triggering mass wasting.
D) It allows farming activity that exposes soil to erosion and mass wasting.

Question 61

Of the following, which one would most likely be triggered by an earthquake?

A) rock avalanche
B) solifluction
C) soil creep
D) slump

Question 62

The mass wasting process in steep mountain areas that causes accumulations of rock debris called talus is called______ .

A) a slump
B) a rock avalanche
C) a rock fall
D) a rock slide

Question 63

When a large cloudburst creates a sudden flow of soil and regolith, we refer to it as ______.

A) a rock fall
B) a slump
C) a debris slide
D) a rock avalanche

Question 64

______involves movement on a zone of compressed air.

A) Soil creep
B) A slump
C) A mudflow
D) A rock avalanche

Question 65

______denotes the exposed, crescent- shaped rupture surface at the head of a slump.

A) Scarp
B) Sole
C) Scoop
D) Toe

Question 66

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

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

Question 67

In the late 1950's the Hebgen Lake earthquake outside of Yellowstone triggered a mass wasting event. The landslide originated on steep mountains slopes where rocks slid off a surface and descended to the valley floor in a few seconds, burying a campground and many people staying there. This type of landslide would be called ______.

A) a rockslide
B) a mudflow
C) an earthflow
D) a slump

Question 68

In deserts of southwestern North America developers often build houses in dry stream beds and build only minimal subsurface drainage systems to handle a flow of water comparable to the size of the dry stream channel. Is this a reasonable development model in the interest of public safety?

A) Yes, although flash floods can occur, using the channel size is a reasonable estimate of the maximum flood size.
B) Yes, any potential flooding catastrophe would be a 100 year flood event and would have adequate warning to evacuate people for safety, so the drainage system is adequate.
C) No, flash floods can produce high viscosity mudflows that would not be captured by the drainage system and could flow out over the valley, destroying everything in its path.
D) No, giant rock avalanches could come down the valley covering houses.

Question 69

A rancher overgrazes his land in an area underlain by heavy clay soils and regolith developed from weathering of claystone. After a series of heavy rains small creeks develop deep gullies along their length. A light steady rain develops and continues for several days. What should the rancher be concerned about on his overgrazed lands?

A) increasing gully development because of the rain
B) slumps along the creeks
C) rock avalanche
D) lahars filling cascading down his creeks, wiping out his cattle

Question 70

What is the greatest danger from earthflow?

A) loss of water quality by mud flowing into river drainages, polluting the water
B) loss of life by rapid downslope movement of the earthflow
C) loss of property along the path of the earthflow
D) deforestation along the earthflow path

Question 71

A geologist is looking at deposits along a river below a large volcano. She finds large boulders mixed with sand and mud, and all of the material is comprised of volcanic rocks, particularly the mud which is volcanic ash. She quickly realizes these deposits represent an ancient ______.

A) rock avalanche
B) lahar
C) earthflow
D) slump

Question 72

Which of the following statements concerning mudflows is not true?

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

Question 73

The most rapid type of mass movement is a ______.

A) slump
B) rock avalanche
C) debris flow
D) lahar

Question 74

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

A) rock avalanche
B) soil creep
C) mudflow
D) solifluction

Question 75

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

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

Question 76

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 lowers the strength and cohesion.
D) Water increases the strength and cohesion.

Question 77

A mass wasting process that involves rapid down- slope movement of debris aided by a cushion of air is called______ .

A) a slump
B) a rock avalanche
C) a rock fall
D) a rock slide

Question 78

Which statement best describes slumping, a mass wasting process?

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

Question 79

Which mass wasting process has the slowest rate of movement?

A) rock avalanche
B) slump
C) rock fall
D) creep

Question 80

Which of the following poses the greatest risk of massive loss of life and property along its path due to how rapidly it moves?

A) earthflow
B) rock avalanche
C) slump
D) rock fall