Deck 4: Weathering, Soil, and Mass Wasting

Question 1

Which term best describes an accumulation of angular rock fragments at the base of a steep, bedrock slope or cliff?

A) trellis slope
B) taliche slope
C) tellus slope
D) talus slope

Answer 1

D

Question 2

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

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

Answer 2

C

Question 3

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

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

Answer 3

C

Question 4

Which of the following best describe the E soil horizon?

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

Question 5

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

Question 6

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

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

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

Question 8

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

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

Question 9

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 process by which weathered rock and mineral particles are removed from one area and transported elsewhere
D) the combined processes of leaching, eluviation, and mass wasting

Question 10

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

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

Question 11

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

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

Question 12

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) removal of soluble chemical constituents from the A and B soil horizons
D) feldspar decomposition and leaching of the soluble products from the C soil horizon

Question 13

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

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

Question 14

The finely divided, red, brown, and yellow soil-coloring minerals originate by what process?

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

Question 15

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

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

Question 16

Which term best describes those processes that move weathered rock materials and soils downslope?

A) podzolization
B) slope sheeting
C) mass wasting
D) talus transfer

Question 17

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

A) 0, A, E, B, C, bedrock
B) A, B, C, D, E, bedrock
C) E, A, B, C, 0, bedrock
D) D, E, C, B, A, bedrock

Question 18

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

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

Question 19

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

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

Question 20

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

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

Question 21

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

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

Question 22

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
A. C-horizon B. A horizon C. E horizon D. B-horizon

Question 23

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 and dropping them a slight distance downslope.
D) Eventually, these cause the soil and regolith to suddenly slide down the slope.

Question 24

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

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

Question 25

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

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

Question 26

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

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

Question 27

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
A. surface area B. rock characteristics C. geologic age D. climate

Question 28

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 29

The most rapid type of mass movement is a ________.

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

Question 30

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 31

Which of the following statements concerning mudflows is NOT true?

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

Question 32

________ involves movement on a zone of compressed air.

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

Question 33

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

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

Question 34

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

Question 35

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.

Question 36

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

A) Mass wasting affects particles of all sizes whereas the others affect only smaller particles.
B) Mass wasting does not require a transporting medium.
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 37

Which statement best describes slumping, a mass wasting process?

A) a block or blocks of unconsolidated regolith slide downhill along a curved slip surface
B) blocks of hard bedrock rapidly slide downhill along fracture surfaces
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 38

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
A. oxidation B. dissolution C. hydrolysis D. sheeting

Question 39

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
A. frost wedging B. mass wasting C. sheeting D. oxidation

Question 40

Which mass wasting process has the slowest rate of movement?

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

Question 41

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

Question 42

Solifluction occurs during the warmer summer months.

Question 43

Like most other liquids, water decreases in volume when it freezes.

Question 44

Quartz is quite resistant to weathering and is an important component of sands in riverbeds and on beaches.

Question 45

Abundant moisture and warm temperatures result in high rates of chemical weathering.

Question 46

Lahars are essentially mudflows associated with volcanoes and volcanism.

Question 47

Chemical weathering in bedrock below the land surface often begins along joints and sheeting fractures.

Question 48

Removal of inorganic soil components from a soil is termed leaching.

Question 49

Ferromagnesian minerals (like olivine and pyroxene) that crystallize at high temperatures in Bowen's reaction series are generally much less susceptible to chemical weathering than quartz.

Question 50

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

Question 51

Sheeting is mainly a process of mechanical weathering.

Question 52

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
A. slope angle B. water C. vegetation D. earthquake

Question 53

Quartz weathers readily to aluminum-rich clay minerals.

Question 54

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
A. earthquake B. lahar C. liquefaction D. landslide

Question 55

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
A. rockslide B. debris flow C. creep D. slump

Question 56

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
A. wind B. water C. mass wasting D. ice

Question 57

Very fine-grained, iron oxide particles account for nearly all red, yellow, and brown soil colors.

Question 58

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

Question 59

The solum or true soil includes all horizons above the C-horizon.

Question 60

Feldspars commonly decompose during weathering to clay minerals, silica, and soluble constituents.

Question 61

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

Question 62

The very fine-sized, clay mineral particles move downward from the E to the B-horizon of some soils. What is this process called?

Question 63

Which form of chemical weathering specifically affects the iron contained in ferromagnesian, rock-forming, silicate minerals?

Question 64

What term describes a soil that has developed from silt and clay deposited by a flooding river?

Question 65

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

Question 66

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

Question 67

________ is the fan-shaped pile of broken rock fragments at the base of a steep, bedrock slope or cliff.

Question 68

________ denotes the downslope movement of soils and regolith.

Question 69

What term refers to removal of soluble inorganic components from soils?

Question 70

Which process of mass wasting occurs primarily in permafrost regions?

Question 71

What kind of weathering involves only a reduction in the sizes of bedrock, regolith, and mineral particles?

Question 72

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

Question 73

What is the most abundant, naturally produced, weak acid involved in chemical weathering and soil formation?

Question 74

Which term denotes the true soil above the zone of partly weathered bedrock?

Question 75

________ involves the downslope movement of a block or blocks of unconsolidated soil and regolith along a curved, slip surface.

Question 76

________ is the basic force that moves or accelerates soil and regolith down a slope.

Question 77

Unconsolidated, granular materials such as gravel and sand will support maximum slope angles of about 33 to 35 degrees. What is the name for this maximum slope angle?

Question 78

As a geologist working in a foreign country for the first time, you are asked to assess the potential for mass wasting in a particular region. What aspects or characteristics (geologic, geographic, biologic, etc.) of the region are you interested in for your assessment? Also, how could you possibly determine if mass wasting has been active in the recent geologic past (100's or 1000's of years)?

Question 79

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

Question 80

Half Dome in Yosemite National Park, California, and Stone Mountain in Georgia, are shaped mainly by what mechanical weathering process?