Chapter Five

1
Chapter Five

• Weathering, Soil, and Mass Movements

2
Weathering

• Weathering is a basic part of the rock cycle and
  a key process in the Earth system.
• Weathering The breaking down and changing of
  rocks at or near Earths surface.
• There are two types of weathering
• Mechanical Weathering
• Chemical Weathering
• Even though they are different, they at are work
  at the same time.

3
Weathering

• Mechanical Weathering
• Occurs when physical forces break rock into
  smaller and smaller pieces without changing the
  rocks mineral composition.
• Each piece has the same composition.
• Breaking a rock into smaller pieces increases the
  surface area of the rock.
• In nature, three physical processes are
  especially important causes of mechanical
  weathering
• Frost wedging
• Unloading
• Biological activity

4
Weathering

• Frost Wedging
• When liquid freezes, it expands by about 9,
  exerting a tremendous outward force.
• When water freezes in the cracks of rocks, it
  enlarges the cracks.
• This process is known as frost wedging.
• It is most common in mountainous regions in the
  middle latitudes.
• Sections of rock that are wedged loose may tumble
  into large piles called talus, which typically
  form at the base of steep, rocky cliffs.

5
Weathering
6
Weathering

• 2. Unloading
• Large masses of igneous rocks may be exposed
  through uplift and erosion of overlying rock.
• When this happens, the pressure exerted on the
  igneous rock is reduced.
• This is known as unloading.
• Unloading causes the outer layers of the rock to
  expand more than the rock below.
• Slabs of outer rock separate like layers of an
  onion and break loose in a process called
  exfoliation.
• Especially common in granite.
• It often produces large, domed shaped rock
  formations.
• Ex Stone Mountain in Georgia and Liberty Cap in
  Yosemite National Park.

7
Weathering
8
Weathering

• 3. Biological Activity
• The activities of organisms, including plants,
  burrowing animals, and humans can also cause
  mechanical weathering.
• Examples
• Tree roots.
• Burrowing animals move rocks to the surface.
• Decaying organisms produce acids which cause
  chemical weathering.
• Humans accelerate weathering through
  deforestation and blasting.

9
Weathering
10
The process that occurs when physical forces
break rock into smaller pieces without changing
the rocks chemical composition is called

• Differential Weathering
• Chemical Weathering
• Mechanical Weathering
• Erosion

11
Which of the following weathering processes
involves the constant freezing and thawing of
water?

• Unloading
• Frost Wedging
• Exfoliation
• Spheroidal Weathering

12
Which of the following is not associated with
mechanical weathering?

• Frost Wedging
• Unloading
• Biological Activity
• Reactions with Oxygen

13
What is responsible for the formation of
exfoliation domes?

• Frost Wedging
• Biological Activity
• Reactions with Oxygen
• Unloading

14
What type of mechanical weathering is most common
in mountainous regions in the middle latitudes?

• Frost Wedging
• Biological Activity
• Oxidation
• Unloading

15
When water freezes, its volume

• Decreases slightly.
• Increases.
• Stays the same.
• Decreases greatly.

16
Weathering

• Chemical Weathering
• Chemical weathering is the transformation of rock
  into one or more new compounds.
• The new compounds remain mostly unchanged as long
  as the environment in which they formed does not
  change.
• Water is the most important agent of chemical
  weathering.
• Water promotes chemical weathering by absorbing
  gases from the atmosphere and the ground.
• These dissolved substances then chemically react
  with various minerals.
• Oxygen dissolved in water reacts easily with
  certain minerals , forming oxides.
• Ex Iron-rich minerals get a yellow to
  reddish-brown coating of iron oxide (rust) when
  they react with oxygen.

17
Weathering

• Water also absorbs carbon dioxide when rain falls
  through the atmosphere.
• Water that seeps into the ground also picks up
  carbon dioxide.
• The dissolved carbon dioxide forms carbonic acid,
  which reacts with many common minerals.
• Carbonic acid is a weak acid found in carbonated
  drinks.

18
Weathering

• Water can also absorb the sulfur oxides in the
  atmosphere produced by the burning of fossil
  fuels (coal and petroleum).
• Through a series of chemical reactions, these
  pollutants are changed into acids that cause acid
  precipitation.
• Acid precipitation accelerates the chemical
  weathering of stone monuments and structures.

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Weathering
20
Weathering

• When granite (feldspar/quartz) is exposed to
  water containing carbonic acid, the feldspar is
  converted mostly into clay minerals.
• As the feldspar is converted into clay, the
  quartz grains are released from the granite.
• Sometimes it is then transported by rivers to the
  ocean where the tiny particles are carried far
  from shore and the quartz crystals are deposited
  near the shore where they become the main
  component of beaches and sand dunes.

21
Weathering

• When silicate minerals undergo chemical
  weathering, the sodium, calcium, potassium, and
  magnesium they contain dissolve and are carried
  away by groundwater.
• The three remaining elements are aluminum,
  silicon, and oxygen which usually combine with
  water and produce clay minerals.

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Weathering
23
Weathering

• Chemical weathering can change the physical shape
  of rock as well as its chemical composition.
• Ex When water enters along the joints in a rock,
  it weather the corners and edges most rapidly. As
  a result, the corners and edges become more
  rounded.
• This process is called spheroidal weathering.
• The rock takes on a spherical shape.
• Spheriodal weathering sometimes causes the outer
  layers of a rock to separate from the rocks main
  body.
• Similar to exfoliation except that they are
  chemically weathered.

24
Weathering
25
Which of the following is not related to chemical
weathering?

• Frost wedging.
• Dissolution
• Reactions with oxygen
• Reactions with water

26
The gradual rounding of the corners and edges of
angular blocks of rock is called

• Exfoliation
• Unloading
• Spheroidal Weathering
• Mechanical Weathering

27
Which of the following is the result of chemical
weathering?

• A rock that has been changed into one or more new
  compounds.
• A rock that has been broken into tiny pieces.
• A rock that has been split in two.
• A rock that has lost its outer layers.

28
The chemical weathering of feldspar produces

• Quartz.
• Iron oxide
• Clay minerals
• Calcium carbonate

29
Whenever the characteristics and chemical
composition of weathered materials have been
altered, they have undergone

• Chemical weathering.
• Mechanical weathering.
• Mass movement.
• Frost wedging.

30
The atmospheric gas that forms a mild acid when
dissolved in water is

• Carbon Dioxide
• Oxygen
• Aluminum
• Sulfur

31
Weathering

• Mechanical weathering affects the rate of
  chemical weathering.
• By breaking rocks into smaller pieces, chemical
  weathering is increased due to the increased
  amount of surface area of the rock.
• Two other factors that affect the rate of
  weathering are
• Rock characteristics
• Climate

32
Weathering

• Rock Characteristics
• Physical characteristics of rock (cracks) are
  important in weathering because they influence
  the ability of water to penetrate rock.
• Mineral composition also affects the rate of
  weathering.
• Ex Granite vs. Marble granite is relatively
  resistant to chemical weathering while marble is
  not very resistant to chemical weathering (reacts
  with weak acids).

33
Weathering

• 2. Climate
• Climatic factors, especially temperature and
  moisture, have a strong effect on the rate of
  weathering (mechanical and chemical).
• The climate most favorable for chemical
  weathering has high temperature and abundant
  moisture.
• Slow in arid and polar regions.

34
Weathering

• Different parts of a rock mass often weather at
  different rates.
• This process, called differential weathering, has
  several causes.
• Differences in mineral composition in one cause.
• More resistant rock protrudes as pinnacles, or
  high peaks.
• Variations in the number and spacing of cracks in
  different parts of a rock mass is another cause
  of differential weathering.

35
Weathering
36
What would cause the inscription on a marble
gravestone to become harder and harder to read
over time?

• Frost wedging
• Mechanical weathering
• Exfoliation
• Chemical weathering

37
Which of the following is not a factor that
affects the rate of weathering in rocks?

• Biological evolution
• Climate
• Rock characteristics
• Amount of exposed surface area

38
Which of these factors affects the rate of
weathering?

• Climate
• Chemical composition of the exposed rock.
• Surface area of the exposed rock.
• All of the above.

39
Rock features such as the sculpted pinnacles seen
in Bryce Canyon National Park are the result of

• Exfoliation.
• Differential Weathering.
• Unloading.
• Frost Wedging.

40
Chemical weathering would be

• Most effective in a warm, dry climate.
• Most effective in a cold, dry climate.
• Most effective in a warm, humid climate.
• Equally effective in any climate.

41
If granite and marble were exposed in an area
with a hot and humid climate,

• The granite would weather most rapidly.
• The marble would weather most rapidly.
• Both rocks would weather at the same rate.
• Neither rock would become weathered.

42
Weathering
43
Soil

• Soil is an important product of weathering.
• All life depends on a dozen or so elements that
  come from Earths crust.
• Weathering produces a layer of rock and mineral
  fragments called regolith.
• Soil is the part of the regolith that supports
  the growth of plants.
• Three important characteristics of soil are its
• Composition
• Texture
• Structure

44
Soil

• Soil Composition
• Soil has four major components
• Mineral Matter (Broken-down rock)
• Organic Matter (Humus decayed organisms)
• Water
• Air
• The percentages of the four major components
  varies greatly.
• In most soils, organic matter (humus) is an
  essential component for plants nutrients and the
  soils ability to retain water.

45
Soil
46
Soil

• 2. Soil Texture
• Most soils contain particles of different sizes.
• Soil texture refers to the proportions of
  different particles sizes.
• To classify soil texture, the U.S. Department of
  Agriculture has established categories based on
  the percentages of clay, silt, and sand in soil.
• Texture strongly influences a soils ability to
  support plant life.

47
Soil
48
Soil

• 3. Soil Structure
• Soil particles usually form clumps that give
  soils a particular structure.
• Soil structure determines how easily a soil can
  be cultivated and how susceptible it is to
  erosion.
• Soil structure also affects the ease with which
  water can penetrate the soil and thus influences
  the movement of nutrients to plant roots.

49
Which of the following is not a major component
of soil?

• Mineral matter
• Air
• Humus
• Earthworms

50
A soils texture is determined by

• Mineral composition
• Type of humus
• Water content
• Particle size

51
The main source of organic matter in soil is

• Water
• Plants
• Fungi
• Bacteria

52
Soil

• Soil forms through the complex interaction of
  several factors.
• The most important factors in soil are
• Parent material
• Time
• Climate
• Organisms
• Slope

53
Soil

• Parent Material
• The source of the mineral matter in soil.
• May be either bedrock (residual soil) or
  unconsolidated deposits such as those in a river
  valley (transported soil).
• The nature of the parent material influences
  soils in two ways
• It affects the rate of weathering and the rate of
  soil formation.
• The chemical makeup of the parents material
  affects the soils fertility.
• Fertility influences the types of plants the soil
  can support.

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Soil
55
Soil

• 2. Time
• The longer a soil has been forming, the thicker
  it becomes.
• The parent material largely determines the
  characteristics of young soils.
• As weathering continues, the influence of the
  parent material can be overshadowed by the other
  factors, especially climate.

56
Soil

• 3. Climate
• Climate has the greatest effect on soil
  formation.
• Variations in temperature and precipitation
  influence the rate, depth, and type of
  weathering.
• The influence of climate is so great that soil
  scientists have found that similar soils can be
  produced from different parent materials in the
  same climate.
• Dissimilar soils can be produced from the same
  parent material in different climates.

57
Soil

• 4. Organisms
• The types of organisms and how many there are in
  a soil have a major impact on its physical and
  chemical properties.
• Scientists name some soils such as prairie
  soil, forest soil, and tundra soil based on the
  soils natural vegetation.
• Plants are the main source of organic matter in
  soil (animals/microorganisms are other sources).
• Microorganisms (fungi, bacteria, and
  single-celled protozoans) play an active role in
  decomposing dead plants and animals (nitrogen gas
  into nitrogen compounds).
• Burrowing animals mix the mineral and organic
  matter in soil.
• Example Earthworms can mix thousands of
  kilograms of soil each year in a single hectare
  (10,000 square meters).

58
Soil

• 5. Slope
• The slope of the land can vary greatly over short
  distances, which results in different soil types.
• Many of the differences are related to the amount
  of erosion and the water content of the soil.
• On steep slopes, erosion is accelerated.
• Little water soaks in, little to no plants, which
  results in thin or nonexistent soils.
• In flat areas, there is little erosion and poor
  drainage.
• Resulting in waterlogged soils that are typically
  thick and dark (large amounts of organic matter).

59
Soil

• The direction the slope faces also affects soil
  formation.
• In the temperate zone of the Northern Hemisphere,
  south-facing slopes receive much more sunlight
  than do north-facing slopes.
• Soils on south-facing slopes are usually warmer
  and drier, which influences the types of plants
  that grow in the soil.

60
Soil
61
The factor that has the greatest effect on soil
formation is

• Climate
• Parent material
• Time
• Slope orientation

62
In which of the following areas will soil
formation be greatest?

• A steep slope in a warm, wet climate.
• A flat area in a cold, wet climate.
• A flat area in a warm, wet climate.
• A north-facing area on a steep slope.

63
Soil that forms on unconsolidated deposits is
called

• Transported soil
• Humus
• Residual soil
• Bedrock

64
Soil

• The processes that form soil operate from the
  surface downward.
• Soil varies in composition, texture, structure,
  and color at different depths.
• These variations divide the soil into zones known
  as soil horizons.
• A vertical section through all of the soil
  horizons is called a soil profile.
• In some soil profiles, the soil horizons blend
  gradually from one to another, in others, they
  are quite distinct.
• Mature soils usually have three distinct soil
  horizons (A, B, and C Horizons).

65
Soil

• A Horizon
• Commonly known as topsoil.
• Upper part consists mostly of organic matter.
• Full of insects, fungi, and microorganisms.
• Lower part is a mixture of mineral matter and
  organic matter.
• 2. B Horizon
• Commonly known as subsoil.
• Contains fine clay particles washed out of the A
  Horizon.
• In some soils, the clay that accumulates in the B
  Horizon forms a compact, impenetrable layer
  called hardpan.
• Is the lower limit of most plant roots and
  burrowing animals.
• C Horizon
• Between the B Horizon and the unaltered parent
  material.
• Contains partially weathered parent material.
• Resembles parent material.

66
Soil
67
In a well-developed soil profile, which horizon
is the uppermost layer?

• The C Horizon.
• The B Horizon.
• The A Horizon.
• The Parent Horizon.

68
What kind of material is found in the C horizon
of a soil profile?

• Partially weathered parent material.
• Clay Particles.
• Hardpan.
• Mineral and organic matter.

69
How are soil horizons ordered from the top of the
profile to the bottom?

• A, C, B
• A, B, C
• C, B, A
• B, A, C

70
The B horizon is also called the

• Topsoil
• Unaltered parent material
• Partially altered parent material
• Subsoil

71
Soil

• Climate has a major effect on the type of soil
  that forms.
• Three common types of soil are
• Pedalfer
• Pedocal
• Laterite
• Pedalfer
• Usually forms in temperate areas that receive
  more than 63-cm (25 inches) of rain each year.
• Present in much of the eastern half of the U.S.,
  mostly in forested regions.
• The B Horizons in pedalfers contain large amounts
  of iron oxide and aluminum-rich clays, giving it
  a brown to red-brown color.

72
Soil

• 2. Pedocal
• Found in the drier western U.S. in areas that
  have grasses and brush vegetation.
• Generally contains less clay than pedalfers.
• Contain abundant calcite, or calcium carbonates,
  and are typically a light gray-brown.
• 3. Laterite
• Form in hot, wet tropical areas.
• Are usually deeper than soils that develop over a
  similar period in temperate areas.
• The large quantity of water that filters through
  these soils removes most of the calcite and
  silica.
• Iron oxide and aluminum oxide are left behind.
• The iron oxide gives laterite a distinctive
  orange to red color.
• When dried, laterite becomes very hard and
  practically waterproof (bricks).

73
Soil
74
Soil

• Laterite contains almost no organic material.
• With the lack of organic material, the soil
  cannot support agriculture for more than a few
  years.
• The nutrients that the soil does have are quickly
  washed out by the plentiful rainwater that
  filters through the soil.

75
A soil that is characteristic of the humid
eastern U.S. is

• Laterite.
• Pedalfer.
• Pedocal.
• Humus.

76
The soil associated with the hot and wet tropics
is

• Laterite
• Pedocal
• Pedalfer
• Bedrock soil

77
Laterite soils contain high amounts of

• Organic material
• Iron oxide
• Calcite
• Calcium carbonate

78
Pedalfer soils would most likely be found

• On an island close to the equator.
• In a tropical rainforest.
• In the dry areas of the western U.S.
• In the eastern half of the U.S.

79
Which of the following is not true of laterite
soils?

• They form in the wet tropics.
• They are red in color.
• They are enriched in iron oxide.
• They are very productive agriculturally.

80
Soil

• Soils are among our most abused resources.
• The loss of fertile topsoil is a growing problem
  as human activities disturb more of Earths
  surface.
• Water erodes soil every time it rains (tiny
  bombs).
• When water flows across the surface it then
  carries away dislodged particles, which is called
  sheet erosion.

81
Soil
82
Soil

• After flowing as a thin sheet for a short
  distance, the water forms tiny streams called
  rills.
• As more water enters the rills, they erode the
  soil further, creating trenches known as gullies.

83
Soil
84
Soil

• Human activities that remove natural vegetation,
  such as farming, logging, and construction, have
  greatly accelerated erosion.
• Without plants, soil is more easily carried away
  by wind and water.
• Scientists can estimate the rate of erosion due
  to water by measuring the amount of sediment in
  rivers.
• These estimates indicate that before humans
  appeared, rivers carries about 9 trillion
  kilograms of sediment to the oceans each year.
• The amount of sediment currently transported to
  the sea by rivers is about 24 trillion kilograms
  per year.

85
Soil

• Wind generally erodes soil much more slowly than
  water does.
• During a long drought, strong winds can remove
  large quantities of soil from unprotected fields.
• Example 1930s Great Plains Dust Bowl.
• The rate of erosion depends on soil
  characteristics and on factors such as climate,
  slope, and type of vegetation.
• In many regions, including about one-third of the
  worlds croplands, soil is eroding faster than it
  is being formed.
• This results in lower productivity, poorer crop
  quality, and a threatened world food supply.

86
Soil

• Another problem caused by erosion is the
  deposition of sediment.
• Rivers that accumulate sediment must be dredged
  to remain open for shipping.
• As sediment settles in reservoirs, they become
  less useful in storing water, controlling floods,
  and generating electricity.
• Some sediments are contaminated with agricultural
  pesticides.
• Sediments also contain soil nutrients, which may
  come from natural processes and from added
  fertilizers.
• Excessive nutrient levels in lakes stimulate the
  growth of algae and plants, which accelerates a
  process that eventually leads to the early death
  of the lake.

87
Soil

• We can significantly slow erosion by using soil
  conservation measures
• Preserve environments
• Protect the land.
• These measures include planting rows of trees
  (windbreaks), plowing along the contours of
  hills, and rotating crops.
• Preserving fertile soil is essential to feeding
  the worlds rapidly growing population.

88
Compared to the past, rates of soil erosion are

• About the same.
• Faster.
• Slower.
• More unpredictable.

89
Which of the following human activities has
caused an increase in soil erosion?

• Clear-cut logging.
• Clearing land for construction.
• Plowing land for farming.
• All of the above.

90
The rate of soil erosion depends on

• Climate.
• Slope steepness.
• The type of vegetation.
• All of the above.

91
Since humans have appeared, the amount of
sediments carried by rivers has

• Increased dramatically.
• Increased slightly.
• Stayed about the same.
• Decreased by about half.

92
What is the correct order for water eroding soil?

• Gullies, rills, sheet erosion.
• Sheet erosion, rills, gullies.
• Sheet erosion, gullies, rills.
• Rills, sheet erosion, gullies.

93
Mass Movements

• The transfer of rock and soil downslope due to
  gravity is called mass movement.
• Ex Landslides
• The combination of weathering and mass movement
  produce most landforms.
• Once weathering weakens and breaks rock apart,
  mass movement moves the debris downslope.
• There a stream usually carries is away.
• Stream valleys are the most common of Earths
  landforms.

94
Mass Movements

• Several factors make slopes more susceptible to
  the pull of gravity.
• Saturation of surface materials with water.
• Oversteepening of slopes.
• Removal of vegetation.
• Earthquakes.
• Water
• Heavy rains and rapid melting of snow can trigger
  mass movement by saturating surface materials
  with water.
• When the pores in sediment become filled with
  water, the particles slides past one another
  easily.

95
Mass Movements

• 2. Oversteepened Slopes
• Loose soil particles can maintain a relatively
  stable slope up to a certain angle (25 to 40),
  depending on the size and shape of the particles.
• If the steepness of the slope exceeds the stable
  angle, mass movement is likely.
• Such slopes are said to be oversteepened.
• This can result when
• Streams undercut a valley wall.
• Waves pound against the base of a cliff.
• People, through excavation during construction of
  roads/buildings.

96
Mass Movements

• 3. Removal of Vegetation
• Plants make slopes more stable because of their
  root systems.
• When plants are removed, mass movements are
  likely.
• 4. Earthquakes
• Earthquakes are one of the most dramatic triggers
  of mass movements.
• They can dislodge rock and unconsolidated
  material, which can cause more damage than the
  earthquake itself.

97
The process responsible for moving material
downslope under the influence of gravity is called

• Erosion
• Weathering
• Mass movement
• Soil formation

98
What is the force behind mass movements?

• The Suns energy
• Flowing water
• Gravity
• Moving ice

99
Which of the following is not true about mass
movements?

• Some mass movements are too slow to be seen.
• Mass movements always lead to landslides.
• Gravity is the driving force behind all mass
  movements.
• Mass movements are always downslope.

100
What factor commonly triggers mass movements?

• Saturation of surface materials with water.
• Earthquakes
• Removal of vegetation
• All of the above

101
Why can the removal of vegetation trigger mass
movements?

• The soil loses nutrients and begins the crumble.
• The plant roots bind the soil and regolith
  together.
• The shaking triggers mass movements.
• The plant roots lubricate the loose sediment.

102
Oversteepened slopes often lead to mass movements
because

• Plants cannot grow on them.
• The angle of their slope is between 10 and 20
  degrees.
• The angle of their slope is less than 20 degrees.
• The angle of their slope is greater than 40
  degrees.

103
During what season would you expect mass
movements to be a greater threat?

• A dry summer.
• A wet spring before vegetation is growing.
• A wet spring with lots of growing vegetation.
• A dry autumn after the leaves have turned.

104
Mass Movements

• Geologists classify mass movements based on the
  kind of material that moves, how is moves, and
  the speed of the movement.
• Rockfalls
• Occurs when rocks or rock fragments fall freely
  through the air.
• Common of slopes that are too steep for loose
  material to remain on the surface.
• Result from the mechanical weathering of rock
  caused by freeze-thaw cycles or plant roots.
• Sometimes trigger other mass movements.

105
Mass Movements

• 2. Slides
• A block of material moves suddenly along a flat,
  inclined surface.,
• Slides that include segments of bedrock are
  called rockslides.
• Often occur in high mountain areas.
• i.e. Andes, Alps, Rockies.
• Rockslides are among the fastest mass movements
  (speeds over 200 kmph 125 mph).
• Triggered by rain or melting snow.

106
Mass Movements

• 3. Slumps
• Is the downward movement of a block of material
  along a curved surface.
• Usually does not travel very fast or very far.
• Slumps leave a crescent-shaped cliff just above
  the slump.
• Common on oversteepened slopes where the soil
  contains thick accumulations of clay.

107
Mass Movements

• 4. Flows
• Mass movements of material containing a large
  amount of water, which move downslope as a thick
  liquid.
• Flows that move quickly, called mudflows, are
  common in semiarid mountainous regions.
• i.e. Southern California
• Follows the contours of the canyon, taking trees
  and boulders with it.

108
Mass Movements

• Earthflows are flows that move relatively slow
  from about a millimeter per day to several meters
  per day, and may continue for years.
• Occurs most often on hillsides in wet regions.
• When water saturates the soil and regolith on a
  hillside, the material breaks away, forming a
  tongue-shaped mass.
• They range in size from a few meters long and
  less than 1 m deep to over 1 km long and more
  than 10 m deep.

109
Mass Movements

• 5. Creep
• The slowest type of mass movement.
• Usually only travels a few millimeters or
  centimeters per year.
• Because it is slow, you cannot directly observe
  it.
• Alternating between freezing and thawing
  contributes to creep.
• Effects are easy to recognize
• Structures once vertical tilt downhill.
• Displacement of fences.
• Cracks in walls and underground pipes.

110
A mass movement that involves the sudden movement
of a block of material along a flat, inclined
surface is called a

• Slide
• Rockfall
• Slump
• Flow

111
When a block of material moves downslope along a
curved surface, the type of mass movement is
called

• A rockfall
• A rockslide
• A slump
• Creep

112
What is the slowest type of mass movement?

• A slump
• A rockfall
• An earthflow
• Creep

113
A relatively rapid form of mass movement that is
most common in dry mountainous regions is

• Creep
• A mudflow
• A slump
• An earthflow

114
Which of the following statements best describes
a slump?

• Slippage of a block of material moving along a
  curved surface.
• Blocks of rock sliding down a slope.
• Rapid flow of water-saturated debris, most common
  in mountainous regions.
• Slow downhill movement of soil and regolith.

115
Alternate freezing and thawing often leads to

• Creep
• Slumps
• Mudflows
• Earthflows