1. Interactions Between the Climate and Plate Tectonic Systems
Grotzinger • Jordan
Understanding Earth
Seventh Edition
Chapter 16:
WEATHERING, EROSION,
AND MASS WASTING
Interactions Between the Climate and Plate Tectonic Systems
© 2014 by W. H. Freeman and Company

2. Weathering, Erosion, and Mass Wasting:
Chapter 16
Weathering,
Erosion, and Mass Wasting:
Interactions
between the Climate and Plate Tectonic Systems

3. About Weathering, etc.
Weathering produces all the soils, clays, sediments, and dissolved substances.
Erosion is the removal of sediments by natural processes such as wind and rivers.
Mass wasting is the downslope movement of masses of Earth materials.

4. Lecture Outline Weathering, erosion, mass wasting, and the rock cycle
2. Controls on weathering
3. Chemical weathering
4. Physical weathering
5. Soils: the residue of weathering

5. Lecture Outline 6. Mass wasting 7. Classification of mass movements
8. Understanding the origins of mass movements

6. Weathering, Erosion, Mass Wasting, and the Rock Cycle
● Weathering is the process of
converting rock into sediment and
forming soils, a main process in the
rock cycle.
● Erosion and mass wasting are the
processes that loosen and transport
soil and rock downhill.

7. ● Properties of the parent rock ● various minerals weather at
2. Controls on Weathering
● Properties of the parent rock
● various minerals weather at
different rates
● a rock’s structure affects
its susceptibility to cracking
and fragmentation

8. ● Other important factors ● climate (rainfall and temperature)
2. Controls on Weathering
● Other important factors
● climate (rainfall and
temperature)
● soil (presence or absence)
● time (length of exposure)

9. 2. Controls on Weathering

10. ● Occurs when minerals react with air and water
3. Chemical Weathering
● Occurs when minerals react
with air and water
● role of water (hydrolysis)
● carbon dioxide (carbonic
acid)
● moist soils

11. The Disintegration of Granite
3. Chemical Weathering:
The Disintegration of Granite

12. The Disintegration of Granite
3. Chemical Weathering:
The Disintegration of Granite

13. The Role of Increasing Surface Area
3. Chemical Weathering:
The Role of Increasing Surface Area
2 cm
2 cm

14. 2 cm
1 cm
1 cm
2 cm

15. 2 cm
1 cm
1 cm
2 cm
Large rocks have less
surface area for chemical
weathering …

16. 2 cm
1 cm
1 cm
2 cm
Large rocks have less
surface area for chemical
weathering…
… than small rocks do,
so smaller rocks weather
more quickly.

17. 3. Chemical Weathering:
Carbon Dioxide

19. ● Chemical stability: a speed control for weathering ● solubility
3. Chemical Weathering
● Chemical stability: a speed
control for weathering
● solubility
● rate of dissolution
● relative stability of common
rock-forming minerals

21. ● Role of oxygen in weathering: from iron silicates to iron oxides
3. Chemical Weathering
● Role of oxygen in weathering:
from iron silicates to iron oxides
● ferric and ferrous iron
● hematite, a common mineral
● red and brown – the colors of
oxidized iron

22. Chemical Weathering: Iron and Oxygen
Pyroxene dissolves,
releasing silica and
ferrous iron.
Pyroxene (FeSiO3)
Silica
Ferrous
iron
Ferrous iron is oxidized,
forming ferric iron.
Ferric iron
Ferric iron precipitates
a solid, iron oxide.
Iron oxide (hematite)
Fe2O3

23. 3. Chemical Weathering: Red Means Iron

24. Thought questions for this chapter
Which igneous rock would you expect to weather faster, a granite or a basalt? What factors influenced your answer?
Assume that a granite with crystals about 4 mm across and a rectangular system of joints spaced about 0.5 to 1 m apart is weathering at the Earth’s surface. What size would you ordinarily expect the largest weathered particle to be?

25. Thought questions for this chapter
Rank the following rocks in order of the rapidity with which they would weather in a warm, humid climate: a sandstone made of pure quartz, a limestone made of pure calcite, a granite, and an evaporite deposit of halite.
What would a planet look like if no weathering occurred at the surface?

26. ● What determines how rock breaks? ● natural zones of weakness
4. Physical Weathering
● What determines how rock breaks?
● natural zones of weakness
● activity of organisms
● frost wedging
● exfoliation

27. 4. Physical Weathering: Joints in Rocks

28. 4. Physical Weathering: Frost Wedging

29. 4. Physical Weathering: Exfoliation

30. ● Physical weathering and erosion ● duration of weathering
● bedrock type
● climate
● topography

31. 4. Physical Weathering

32. Thought questions for this chapter
Why do you think a road built of concrete, an artificial rock, tends to crack and develop a rough, uneven surface in a cold, wet region even when it is not subjected to heavy traffic?
Pyrite is a mineral in which ferrous iron is combined with sulfide ions. What major chemical process weathers pyrite?

33. ● Soils as geosystems ● input material ● transformations and
5. Soil: The Residue of Weathering
● Soils as geosystems
● input material
● transformations and
translocations
● output material

34. ● The basic soil-forming processes result in losses
5. Soil: The Residue of Weathering
● The basic soil-forming
processes result in losses
(transformations) and
additions (translocations).

35. Losses Additions Organic material Airborne dust Water erosion
Chemicals
and
minerals
from
bedrock
Wind
Leaching
BEDROCK

36. Losses Additions Organic material Airborne dust Water erosion
Chemicals
and
minerals
from
bedrock
Wind
Leaching
BEDROCK
Minerals, grains,
and aggregates
may move
through the soil.
TRANSLOCATION

37. Losses Additions Organic material Airborne dust Water erosion
Chemicals
and
minerals
from
bedrock
Wind
Leaching
BEDROCK
Minerals are transformed
into other minerals.
Minerals, grains,
and aggregates
may move
through the soil.
Other minerals
precipitate from fluids.
TRANSLOCATION
TRANSFORMATION

38. Losses Additions Organic material Airborne dust Water erosion
Chemicals
and
minerals
from
bedrock
Wind
Leaching
BEDROCK
Minerals are transformed
into other minerals.
Minerals, grains,
and aggregates
may move
through the soil.
Other minerals
precipitate from fluids.
TRANSLOCATION
TRANSFORMATION
Transformation and translocation
occur throughout the soil profile.

39. Part 1 of 2

40. Part 2 of 2

41. ● Paleosols – ancient soils ● climate history ● ancient atmosphere
5. Soil: The Residue of Weathering
● Paleosols – ancient soils
● climate history
● ancient atmosphere
● history of erosion

42. Thought questions for this chapter
In northern Illinois, you can find two soils developed on the same kind of bedrock: one is 10,000 years old and the other is 40,000 years old. What differences would you expect to find in their compositions or profiles?

43. 6. Mass Wasting
● Mass wasting includes all processes by which masses of rock and soil move downslope.
● Mass movement occurs when the force of gravity exceeds the strength of the material and it moves downslope.

44. ● Three primary factors ● nature of slope materials (angle of repose)
6. Mass Wasting
● Three primary factors
● nature of slope materials
(angle of repose)
● amount of water
● steepness and stability

45. 6. Mass Wasting

46. ● Nature of slope materials ● unconsolidated materials ● sand and silt
6. Mass Wasting
● Nature of slope materials
● unconsolidated materials
● sand and silt
● rock fragments, sand,
silt, and clay

47. The Behavior of Dry and Wet Sand
6. Mass Wasting:
The Behavior of Dry and Wet Sand

50. The
Behavior
of Wet
Sand

51. ● Nature of slope materials ● consolidated materials ● rock
6. Mass Wasting
● Nature of slope materials
● consolidated materials
● rock
● compacted (cohesive)
sediments and soils

52. ● Steepness and stability ● angle of slope ● accumulation of rubble
6. Mass Wasting
● Steepness and stability
● angle of slope
● accumulation of rubble
● breakage into large blocks

53. The Accumulation of Rubble on a Slope
6. Mass Wasting:
The Accumulation of Rubble on a Slope

54. 6. Mass Wasting
● Water content
● lubrication
● liquefaction

55. ● Triggers of mass movements ● earthquake vibrations
6. Mass Wasting
● Triggers of mass movements
● earthquake vibrations
● rainfall and water infiltration
● overloading

56. 6. Mass Wasting

57. Mass
Wasting:
Triggered by
Earthquake

58. Thought questions for this chapter
Would a prolonged drought affect the potential for landslides? How?
What factors weaken rock and enable gravity to start a mass movement?

59. ● Three characteristics used ● nature of material
7. Classification of Mass Movements
● Three characteristics used
● nature of material
(rock or unconsolidated)
● velocity of movement
(slow, moderate, or fast)
● nature of movement
(flow, slide, or fall)

60. Classification
of Mass
Movements
Material

61. Classification
of Mass
Movements
Material
Nature of
motion

62. Classification
of Mass
Movements
Material
Nature of
motion
Velocity

63. 7. Classification of Mass Movements

65. ● Rock mass movements ● rock falls ● rock slides ● rock avalanches
7. Classification of Mass Movements
● Rock mass movements
● rock falls
● rock slides
● rock avalanches

66. 7. Classification of Mass Movements:
Rock Falls

67. 7. Classification of Mass Movements:
Rock Slides

68. Classification
of Mass
Movements:
Rock Slides

69. 7. Classification of Mass Movements:
Rock Avalanches

70. Classification of Mass Movements:
Rock Avalanche

71. ● Unconsolidated mass movements ● creep ● earthflow ● debris flow
7. Classification of Mass Movements
● Unconsolidated mass movements
● creep
● earthflow
● debris flow
● mud flow
● debris avalanche
● slump
● debris slide

72. 7. Classification of Mass Movements:
Creep

73. Classification of Mass Movements:
Creep

74. 7. Classification of Mass Movements:
Earthflow

75. Classification
of Mass
Movements:
Earthflow

76. 7. Classification of Mass Movements:
Debris Flow

77. Classification of Mass Movements:
Debris Flow

78. 7. Classification of Mass Movements:
Mud Flow

79. Classification of Mass Movements:
Mud Flow

80. 7. Classification of Mass Movements:
Debris Avalanche

81. Classification of Mass Movements:
Debris Avalanche

82. Classification of Mass Movements:
Debris Avalanche

83. 7. Classification of Mass Movements:
Slump

84. 7. Classification of Mass Movements:
Debris Slide

85. Classification
of Mass
Movements:
Debris Slide

86. 8. Understanding the Origins
of Mass Movements
● Examples of landslide disasters
● Gros Ventre valley, Wyoming
(1925)
● Vaiont Dam, Italy (1963)

87. Origin of Mass Movement: The Gros
Ventre Disaster, 1925

88. Origin of
Mass
Movement:
The Gros
Ventre
Disaster,
1925

89. Origin of
Mass
Movement:
The Gros
Ventre
Disaster,
1925

90. Origin of
Mass
Movement:
The Gros
Ventre
Landslide
area today

91. 8. Understanding the Origins
of Mass Movements
● The Vaiont Dam disaster (Italy)
● one of world’s largest man-made
lakes was formed by this dam
● steep valley walls were made of
weak, broken, and layered rock

92. 8. Understanding the Origins
of Mass Movements
● The Vaiont Dam disaster (Italy)
● A small rock slide in 1960 should
have been a warning.
● In 1963, 240 million m3 of rock
fell into the lake, bursting the
dam and killing 3,000 people.

94. Thought questions for this chapter
What geologic conditions might you want to investigate before you purchase a house at the base of a steep hill of bedrock covered by a thick layer of soil?
What evidence would you look for to indicate that a mountainous area had undergone a great many prehistoric landslides?
What factors would make the potential for mass movements in a mountainous terrain in the humid tropics greater or less than the potential in similar terrain in a desert?

95. Thought questions for this chapter
What kind(s) of mass movements would you expect on a steep hillside with a thick layer of soil overlying unconsolidated sands and muds after a prolonged period of heavy rain?

96. Key terms and concepts Chemical stability Consolidated material Creep
Angle of repose
Chemical stability
Consolidated material
Creep
Exfoliation
Frost wedging
Hematite
Humus
Kaolinite
Liquefaction
Mass movement
Mass wasting
Slump
Soil
Soil profile

97. Key terms and concepts
Talus
Unconsolidated material