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What is it? Two types:
- Mechanical weathering
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less easily weathered
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Two main types:
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Two main types:- Mechanical weathering- Chemical weathering
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Frost wedging
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Frost wedging Thermal Expansion
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Frost wedging Thermal Expansion Unloading
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Frost wedging Thermal Expansion Unloading
Biological Forces
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Why does this happen?
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Why does this happen? Water e x p a n d s when it freezes!
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Why does this happen?
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Why does this happen?- Change in pressure or temperature
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Why does this happen?- Change in pressure or temperature
Breaks along planes of weakness
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Why does this happen?- Change in pressure or temperature
Breaks along planes of weakness
If rock is homogeneous (no weakness), then
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Why does this happen?- Change in pressure or temperature
Breaks along planes of weakness
If rock is homogeneous (no weakness), then- Fractures form sheets parallel to surface
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Why does this happen?- Change in pressure or temperature
Breaks along planes of weakness
If rock is homogeneous (no weakness), then- Fractures form sheets parallel to surface- "Exfoliation"
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Root wedging Humans!
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1-frost2-thermal3-jointing
4-biological
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1-frost2-thermal3-jointing
4-biological
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Dissolution- enhanced by acidity
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Dissolution- enhanced by acidity
Hydrolysis-
like dissolution, but different mineral is left behind.
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Dissolution- enhanced by acidity
Hydrolysis-
like dissolution, but different mineral is left behind. Oxidation (rust!)
- important for Fe-bearing minerals
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Especially important for calcite, CaCO3(limestone) [demo of limestone + acid]
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Forms clays from most silicates
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Forms clays from most silicates- but not quartz
Clays->shale
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Forms clays from most silicates- but not quartz
Clays->shale- most common
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Forms clays from most silicates- but not quartz
Clays->shale- most common- sedimentary rock
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Forms clays from most silicates- but not quartz
Clays->shale- most common- sedimentary rock feldspar
feldspar altered to
clay
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How does mechanical weathering help chemicalweathering?
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How does mechanical weathering help chemicalweathering? How does chemical weathering help
mechanical?
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Jim Myers,U W
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U Wyo.
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Small and large rainstorms strip weatheredmaterial away
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J. Abraham, Dept.of Soil Sci., SLU
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