Erosion and Weathering
What is erosion?
•
(geology) the mechanical process of wearing or
grinding something down (as by particles washing
over it)
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The wearing away of the earth’s surface by
natural processes
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corrosion: erosion by chemical action
Types of Erosion
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•
•
•
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Water
Wind
Glacier
Soil
Sea
Water
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Occurs from chemicals in the water and the
force and flow of water
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Chemicals break down certain rocks like
limestone or chalk
•
Force of water creates cracks and
crevasses
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These get bigger and bigger as it gets
eroded, particles of the rock get carried in
the water and further aid erosion
Wind
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The wind picks up smaller particles of rock
(pebbles and sand)
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These hit landforms and take pieces off
them
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This friction causes the break up of
landforms
Glacier Erosion
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What is a GLACIER?:
A huge mass of ice slowly flowing over a land mass,
formed from compacted snow in an area where snow
accumulation exceeds melting
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•
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These large bodies of ice that pick up rocks
and earth and erode the earth’s surface
Powerful eroding machine, picking up pieces
of rock the size of houses in some places
Glaciers are so powerful they can carve
valleys and create landforms
Sea Erosion
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Salts and other chemicals in the water erode
coastal rocks
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These are dragged out to sea and deposited
in other areas (Long shore Drift)
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Wave power creates erosion. Also particles
of rock and sediment aid to the erosion
process
Soil Erosion
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Biggest problem for farmers
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Wind and rain remove topsoil and nutrients
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Makes the soil infertile and it breaks up
leaving dongas
TASK
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You are a forester in South Africa and you have just acquired some land and you are faced with a
problem with soil erosion due to poor farming techniques:
YOUR PROBLEM:
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DONGAS CASUED BY EROSION HAVE TAKEN UP CRITICAL SPACE FOR YOU TO PLANT AND GROW
TREES
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•
WHAT STEPS ARE YOU GOING TO TAKE TO REPAIR THE DONGAS?
WHAT IMPROVED PLANTING TECHNIQUES ARE YOU GOING TO USE?
RUBRIC
Rubric for task
1
2
3
4
5
Steps to combat
problem
Just outline
Just points
No steps good points
Good outline good points
Very good step by step
outline with
relevant points
and techniques
Repair Dongas
Just technique no
explanation
No technique vague
explanation
Adequate technique and
vague explanation
Good technique, adequate
explanation
Relevant techniques and
clear explanation
of techniques
Improved faming
methods
Little effort made
Adequate methods no
explanation
Adequate methods and
adequate
explanation
Good methods and good
explanation
Excellent methods and
explanations
Total
15