1. Weathering, Erosion, and
Soil
CHAPTER 7

2. Weathering
SECTION 7.1

4. Introduction

5. Introduction
weathering -the process by which rocks on
or near earth’s surface break down and
change

6. Introduction
weathering -the process by which rocks on
or near earth’s surface break down and
change
erosion - the removal and transport of
weathered materials from one location to
another

7. Mechanical Weathering

8. Mechanical Weathering
mechanical weathering (physical weathering)
- the process by which rocks and minerals
break down into smaller pieces

9. Mechanical Weathering
mechanical weathering (physical weathering)
- the process by which rocks and minerals
break down into smaller pieces
no change in rocks composition

10. Mechanical Weathering
mechanical weathering (physical weathering)
- the process by which rocks and minerals
break down into smaller pieces
no change in rocks composition
only changes size and sometimes shape

11. Temperature

12. Temperature
when water freezes it expands and increases
in volume

13. Temperature
when water freezes it expands and increases
in volume
water in rocks freezes, expands, exerts
pressure on rocks and causes to split

14. Temperature
when water freezes it expands and increases
in volume
water in rocks freezes, expands, exerts
pressure on rocks and causes to split
frost wedging - the repeated thawing
and freezing of water in the cracks of
rocks

15. Temperature
when water freezes it expands and increases
in volume
water in rocks freezes, expands, exerts
pressure on rocks and causes to split
frost wedging - the repeated thawing
and freezing of water in the cracks of
rocks
responsible for formation of potholes
in rocks

17. Pressure

18. Pressure
bedrock @ great depths is under pressure
from overlaying rock

19. Pressure
bedrock @ great depths is under pressure
from overlaying rock
when layers removed, former layers
buried can now expand (cracks form)

20. Pressure
bedrock @ great depths is under pressure
from overlaying rock
when layers removed, former layers
buried can now expand (cracks form)
exfoliation - the process by which outer rock
layers are stripped away

21. Pressure
bedrock @ great depths is under pressure
from overlaying rock
when layers removed, former layers
buried can now expand (cracks form)
exfoliation - the process by which outer rock
layers are stripped away
roots of trees can grow in cracks and
further split rocks

23. Chemical Weathering

24. Chemical Weathering
chemical weathering
- the process by
which minerals
undergo changes in
their composition as
the result of
chemical reactions

25. Chemical Weathering
chemical weathering
- the process by
which minerals
undergo changes in
their composition as
the result of
chemical reactions

26. Chemical Weathering
chemical weathering
- the process by
which minerals
undergo changes in
their composition as
the result of
chemical reactions

27. Chemical Weathering
chemical weathering 5 significant agents:
- the process by
which minerals
undergo changes in
their composition as
the result of
chemical reactions

28. Chemical Weathering
chemical weathering 5 significant agents:
- the process by
which minerals water
undergo changes in
their composition as
the result of
chemical reactions

29. Chemical Weathering
chemical weathering 5 significant agents:
- the process by
which minerals water
undergo changes in
their composition as oxygen
the result of
chemical reactions

30. Chemical Weathering
chemical weathering 5 significant agents:
- the process by
which minerals water
undergo changes in
their composition as oxygen
the result of
chemical reactions carbon dioxide

31. Chemical Weathering
chemical weathering 5 significant agents:
- the process by
which minerals water
undergo changes in
their composition as oxygen
the result of
chemical reactions carbon dioxide
acids

32. Chemical Weathering
chemical weathering 5 significant agents:
- the process by
which minerals water
undergo changes in
their composition as oxygen
the result of
chemical reactions carbon dioxide
acids
temperature

33. Water

34. Water
can dissolve many kinds of minerals and
rocks

35. Water
can dissolve many kinds of minerals and
rocks
has active role in some reactions

36. Water
can dissolve many kinds of minerals and
rocks
has active role in some reactions
serves as medium through which other
reactions occur

37. Water
can dissolve many kinds of minerals and
rocks
has active role in some reactions
serves as medium through which other
reactions occur
hydrolysis - the reaction of water w/
other substances

38. Oxygen

39. Oxygen
can combine w/ other substances

40. Oxygen
can combine w/ other substances
oxidation - the chemical reaction of oxygen
w/ other substances

41. Oxygen
can combine w/ other substances
oxidation - the chemical reaction of oxygen
w/ other substances
ex. iron readily combines w/ oxygen in
atmosphere to form minerals w/ oxidized
form of iron

42. Carbon Dioxide

43. Carbon Dioxide
produced by living organisms during
respiration

44. Carbon Dioxide
produced by living organisms during
respiration
when combined w/ water in air, it forms
weak carbonic acid that falls to earth’s
surface as precipitation

45. Carbon Dioxide
produced by living organisms during
respiration
when combined w/ water in air, it forms
weak carbonic acid that falls to earth’s
surface as precipitation
carbonic acid reacts w/ minerals to
dissolve rock

46. Acid Rain

47. Acid Rain
caused mainly by oxidation of sulfur dioxide
and nitrogen oxides released into air by
human activities

48. Acid Rain
caused mainly by oxidation of sulfur dioxide
and nitrogen oxides released into air by
human activities
2 gases combine w/ oxygen and water in
air to form sulfuric and nitric acid

49. Acid Rain
caused mainly by oxidation of sulfur dioxide
and nitrogen oxides released into air by
human activities
2 gases combine w/ oxygen and water in
air to form sulfuric and nitric acid
pH = 5.6 or lower

50. Acid Rain
caused mainly by oxidation of sulfur dioxide
and nitrogen oxides released into air by
human activities
2 gases combine w/ oxygen and water in
air to form sulfuric and nitric acid
pH = 5.6 or lower
precipitation affects wildlife

51. What Affects the Rate
of Weathering?

52. What Affects the Rate
of Weathering?
natural weathering occurs very slowly

53. What Affects the Rate
of Weathering?
natural weathering occurs very slowly
certain conditions and interactions can
accelerate or slow weathering

54. What Affects the Rate
of Weathering?
natural weathering occurs very slowly
certain conditions and interactions can
accelerate or slow weathering
climate

55. What Affects the Rate
of Weathering?
natural weathering occurs very slowly
certain conditions and interactions can
accelerate or slow weathering
climate
rock type

56. What Affects the Rate
of Weathering?
natural weathering occurs very slowly
certain conditions and interactions can
accelerate or slow weathering
climate
rock type
surface area

57. What Affects the Rate
of Weathering?
natural weathering occurs very slowly
certain conditions and interactions can
accelerate or slow weathering
climate
rock type
surface area
topography

58. Climate

59. Climate
major influence on rate of chemical
weathering

60. Climate
major influence on rate of chemical
weathering
variables of climate:

61. Climate
major influence on rate of chemical
weathering
variables of climate:
precipitation

62. Climate
major influence on rate of chemical
weathering
variables of climate:
precipitation
temperature

63. Climate
major influence on rate of chemical
weathering
variables of climate:
precipitation
temperature
evaporation

64. Climate cont...

65. Climate cont...
interaction b/c temperature and precipitation
has greatest effect

66. Climate cont...
interaction b/c temperature and precipitation
has greatest effect
chemical weathering occurs readily in
climates of warm temperatures

67. Climate cont...
interaction b/c temperature and precipitation
has greatest effect
chemical weathering occurs readily in
climates of warm temperatures
physical weathering occurs readily in cool,
dry climates

68. Rock Type and
Composition

69. Rock Type and
Composition
how hard or resistant rocks are to be broken
down, depends on their type an composition

70. Rock Type and
Composition
how hard or resistant rocks are to be broken
down, depends on their type an composition
sedimentary rocks more easily weathered
than harder igneous and metamorphic
rocks

72. Surface Area

73. Surface Area
as pieces get smaller, surface areas increase

74. Surface Area
as pieces get smaller, surface areas increase
the higher the total surface area, the
more weathering that occurs

76. Topography and Other
Variables

77. Topography and Other
Variables
materials on level areas likely to remain in place as
they undergo changes

78. Topography and Other
Variables
materials on level areas likely to remain in place as
they undergo changes
materials on slopes have greater tendency to move as
result of gravity

79. Topography and Other
Variables
materials on level areas likely to remain in place as
they undergo changes
materials on slopes have greater tendency to move as
result of gravity
as move down slope, exposes underlying rock
surfaces and provides more opportunities for
weathering to occur

80. Topography and Other
Variables
materials on level areas likely to remain in place as
they undergo changes
materials on slopes have greater tendency to move as
result of gravity
as move down slope, exposes underlying rock
surfaces and provides more opportunities for
weathering to occur
organisms affect weathering

81. Topography and Other
Variables
materials on level areas likely to remain in place as
they undergo changes
materials on slopes have greater tendency to move as
result of gravity
as move down slope, exposes underlying rock
surfaces and provides more opportunities for
weathering to occur
organisms affect weathering
decaying organic matter

82. Topography and Other
Variables
materials on level areas likely to remain in place as
they undergo changes
materials on slopes have greater tendency to move as
result of gravity
as move down slope, exposes underlying rock
surfaces and provides more opportunities for
weathering to occur
organisms affect weathering
decaying organic matter
living plant roots

83. Erosion and Deposition
SECTION 7.2

84. Intro

85. Intro
erosion process that transports earth’s
minerals from one location to another

86. Intro
erosion process that transports earth’s
minerals from one location to another
running water, glaciers, wind, and ocean
currents

87. Intro
erosion process that transports earth’s
minerals from one location to another
running water, glaciers, wind, and ocean
currents
deposition - minerals are dropped in
another location

88. Gravity’s Role in Erosion

89. Gravity’s Role in Erosion
force gravity pulls materials down slope

90. Gravity’s Role in Erosion
force gravity pulls materials down slope
w/out gravity, glaciers would not move
downslope and streams would not flow

91. Erosion by Running
Water

92. Erosion by Running
Water
water has a lot of power to move large particles

93. Erosion by Running
Water
water has a lot of power to move large particles
great potential to erode materials b/c steeper
slope, faster water flows

94. Erosion by Running
Water
water has a lot of power to move large particles
great potential to erode materials b/c steeper
slope, faster water flows
small streams join into larger streams (watershed)

95. Erosion by Running
Water
water has a lot of power to move large particles
great potential to erode materials b/c steeper
slope, faster water flows
small streams join into larger streams (watershed)
rill erosion - erosion by running water in small
channels, on side of slope

96. Erosion by Running
Water
water has a lot of power to move large particles
great potential to erode materials b/c steeper
slope, faster water flows
small streams join into larger streams (watershed)
rill erosion - erosion by running water in small
channels, on side of slope
gully erosion - when channels becomes steep and
wide

97. Erosion by Running
Water
water has a lot of power to move large particles
great potential to erode materials b/c steeper
slope, faster water flows
small streams join into larger streams (watershed)
rill erosion - erosion by running water in small
channels, on side of slope
gully erosion - when channels becomes steep and
wide
problem in farming and grazing areas

98. Costal Deposition and
Erosion

99. Costal Deposition and
Erosion
weathering process continue in ocean

100. Costal Deposition and
Erosion
weathering process continue in ocean
ocean currents, waves, and tides carve
out cliffs, arches, and edges of continents

101. Costal Deposition and
Erosion
weathering process continue in ocean
ocean currents, waves, and tides carve
out cliffs, arches, and edges of continents
sand particles accumulate on shorelines
forming dunes and beaches

102. Costal Deposition and
Erosion cont...

103. Costal Deposition and
Erosion cont...
erosion occurs

104. Costal Deposition and
Erosion cont...
erosion occurs
constant movement of water

105. Costal Deposition and
Erosion cont...
erosion occurs
constant movement of water
sand repeatedly picked up and moved

106. Costal Deposition and
Erosion cont...
erosion occurs
constant movement of water
sand repeatedly picked up and moved
sandbars form

107. Costal Deposition and
Erosion cont...
erosion occurs
constant movement of water
sand repeatedly picked up and moved
sandbars form
can turn into barrier islands

108. Glacier Erosion

109. Glacier Erosion
erosional effects large-scale and dramatic

110. Glacier Erosion
erosional effects large-scale and dramatic
scrape and gorge out large sections

111. Glacier Erosion
erosional effects large-scale and dramatic
scrape and gorge out large sections
can carry huge rocks and piles of debris over
great distance

112. Glacier Erosion
erosional effects large-scale and dramatic
scrape and gorge out large sections
can carry huge rocks and piles of debris over
great distance
features left in wake of glacier movement:

113. Glacier Erosion
erosional effects large-scale and dramatic
scrape and gorge out large sections
can carry huge rocks and piles of debris over
great distance
features left in wake of glacier movement:
valleys, majestic water falls, lakes,
deposits of sediment

114. Wind Erosion

115. Wind Erosion
major erosional agent in areas that
experience limited rain and high
temperatures

116. Wind Erosion
major erosional agent in areas that
experience limited rain and high
temperatures
areas have little vegetation to hold
sediments in place

117. Wind Barriers

118. Wind Barriers
reduces effect of wind erosion

119. Wind Barriers
reduces effect of wind erosion
trees and other vegetation planted
perpendicular to direction of wind

120. Erosion by Plants,
Animals, and Humans

121. Erosion by Plants,
Animals, and Humans
as plants and animals carry on life process
they move materials from one place to
another

122. Erosion by Plants,
Animals, and Humans
as plants and animals carry on life process
they move materials from one place to
another
humans excavate areas