Weathering and Erosion
What is Weathering?
•
•
_________________________________________________________________
Two Types
– __________________
– _______________________
What is Mechanical Weathering?
•
•
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When physical forces break rock into smaller pieces
Does not change the rock’s composition
Three Ways
– _____________
– _________
_________
– _____________
Mechanical Weathering: Frost Wedging
•
•
•
__________________________________________________
Water freezes expanding the cracks
Eventually breaking rocks into pieces
Mechanical Weathering: Unloading
•
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The uplift and weathering of rocks overlying igneous rocks
Why?
– Pressure on igneous rocks is reduced causing uplift
Exfoliation: ____________________________________________
Mechanical Weathering: Biological Activity
•
•
_____________________________________
Example:
– Plant roots wedge into rocks, breaking them apart
What is Chemical Weathering?
•
_____________________________________________
Agents of Chemical Weathering
•
Water
– ______________
______________
______________
– Picks up gases
from the
atmosphere
•
Oxygen
– ______________
______________
______________
– Ex: rusting
•
Carbon Dioxide
– Combines with
water in the
atmosphere
– ______________
______________
______________
______________
______________
Chemical Weathering in Action
•
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Granite
– _______________________________
– _______________________________
Spheroidal Weathering
– ______________________________________
Rate of Weathering: What affects it?
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Rock Characteristics
– ________________________
– ________________________
Climate
– ________________________
– ________________________
What is Soil?
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Part of the regolith that supports the growth of plants
Regolith
– ________________________________________________________________
How is Soil Formed?
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Weathering of rocks that is carried away
Factors
– ______________
– ______________
– ______________
– ______________
– ______________
– ______________
Soil Formation Factors
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•
Parent Material
– ________________
_________________
Time
– ______________
______________
– The longer a soil has
been forming, the
thicker it becomes
•
Climate
– _______________
_______________
– Influences of
temperature and
precipitation affect
rate, depth and type of
weathering
Characteristic of Soil: Soil Composition
• 45% mineral matter
• 25% air
• 25% water
• 5% humus
– _________________________________
•
•
Organisms
– ______________
______________
Slope
– Steep slopes often
have ___________
_______________
_______________
Characteristic of Soil: Soil Texture
•
_______________________________________
– Sand (large size)
– Silt (feels like flour)
– Clay (small size)
– Loam (mix of all three; best for plants)
Characteristic of Soil: Soil Structure
•
_____________________________________
Soil Types
•
•
•
Pedalfer
– _____________________________
Pedocal
– _____________________________
Laterite
– _____________________________
What is Erosion?
•
_________________________________________________________________
Agents of Erosion
•
•
•
_______________________
_______________________
_______________________
What happens to the Material?
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Deposition
– _____________________________
– _____________________________
How does Water Erode Soil?
•
___________________________________
Process of Water Erosion
1. Sheet Erosion
– ___________________________
2. Rills
– ___________________________
3. Gullies
– ____________
• Each move the soil a small distance
•
•
____________________________
____________________________
What is a Glacier?
•
Large, moving mass of ice that forms near Earth’s poles and in mountainous regions at high elevations
How do Glaciers Erode Soil?
•
•
________________________________________________
Can carry huge rocks and piles of debris over great distance
Landforms Created by Glaciers
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Glaciated Valley
– _____________________
Cirques
– Bowl-shaped depression at the head of a glaciated valley, that is surrounded on three sided by
steep rock walls
Arêtes
– _____________________
Horns
– _____________________
How does Wind Erode Soil?
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Strong in areas of little vegetation cover
Picks up and carry sediment
These particle batter other structures
Landscapes Shaped by Wind
•
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Sand Dunes
– ________________________
– ________________________
Loess
– ____________________________________
How can humans control erosion?
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Planting rows of trees called windbreakers
Terracing hillsides
Plowing along the contours of hills
Rotating crops
What is Mass Movement?
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The transfer of rock and soil down-slope due to __________________________
Triggers of Mass Movement
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Water
– ____________________________
____________________________
– ____________________________
Over-steepened Slopes
– ____________________________
____________________________
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Removal of Vegetation
– ________________________
– Removing plants increase chances of
movement and erosion
Earthquakes
– ___________________________
How to Classify Mass Movement?
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Classified by
– ________________________
– ________________________
– ________________________
Types of Mass Movement
_________________
• When rock or rock fragments fall freely
through the air
_________________
• A block of material moves suddenly along a
flat, inclined surface
• _______________
– Include segments of bedrock
• _______________
– Movement of relatively thin block of
loose soil, rock and debris
_____________________
• Downward movement of block of material
along a curve surface
____________________________
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•
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•
Dig series of tranches to divert running water
Constructing protective fences on highways
Retaining walls for weak slopes
Don’t build on steep slopes
_____________________
• Containing a large amount of water which
move downslope as a thick fluid
• _________________
– Swiftly moving mixture of mud and
water
• ________________
– Moves relatively slow
– Carry clay-rich sediment
_______________________
• Extremely rapid movement of Earth material
or snow
__________________
• Slow, downhill movement of soil
• Only noticeable over long period time
• Slowest type of mass movement