Mechanical,Biological and Chemical weathering

Details on mechanical and chemical weathering

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Types of mechanical weathering

Freeze thaw/frost shattering: When water gets into cracks in rocks during the day and during the night it freezes (Total volume expansion of 9%) and this widens the rock, eventually causing the rock to shatter.

Salt Crystallisation: This is when saline water enters the pores of the rocks and then evaporates, this leaves the salt crystals behind. This process repeats a lot of times until eventually the crystals become so large that the rock disintegrates.

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Types of mechanical weathering

Exfoliation: This occurs in places with great fluctuations in temperature. The outer layer of rocks heat up and cool faster than the inner ones causing the outer layers to peel off like an onion. This process can produce exfoliation domes!

Pressure Release: This is when Granite rocks that have developed under considerable pressure and then in the future this pressure is taken away and the granite exposed and this causes a release of pressure, this weakens the rock allowing other processes to develop.

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Biological Weathering

This is basically when tree roots grow along bedding planes or extend into joints widening them until blocks of rocks become detached.

It is also said that burrowing animals may also weather rocks!

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Types of Chemical Weathering

Oxidation: When rocks that are exposed to oxygen react with it and become a browinsh color (sort of like rusting!) which weakens the rock and makes it more vunerable.

Reduction: The opposite of oxidation.

Hydration: When rocks absorb water into their structure causing them to swell and become vunerable to future breakdown.

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Types of Chemical Weathering

Carbonation: This is when rainwater (which naturally contains carbon dioxide) in solution has a carbonic acid. And this weak acid can react with rocks that contain calcium carbonate such as limestone. The limestone over time dissolves as calcium bicarbonate

Hydrolysis: When hydrogen in water reacts with minerals in rocks causing the water to combine with the mineral. This decomposes the rock and forms clays.

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