Weathering- Phys Geog

Summarising the types of weathering and its effects.

Cliff Collapse

Weathering

weakening or decaying of rocks
in original place
on or close to ground

caused by weather factors (rainfall and temp change)

Mechanical

disintegration of rocks
scree found at foot of cliff

Chemical

Chemical changes
Slightly acidic rainwater
Dissolves certain rock types

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Freeze-thaw weathering

Water collects in cracks in rock during day
Night- temp below 0 degrees Celsius
Water freezes & expands by around 9%
Puts pressure on surrounding rock
Widens existing cracks

Ice melts in morning- pressure removed
Repeated cycles of freezing & thawing causes rock to break up

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Salt weathering

Sea water contains salt
Water evaporates- leaving salt crystals
Salt crystals grow + expand in cracks & holes
Puts pressure on rock- bits may break off

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Chemical Weathering & Mass Movement

Carbonation

Rocks made of calcium carbonate
Dissolve in water

Rainwater- absorbs CO2 from air
Becomes slightly acidic

Contact with alkaline rock produces chemical reaction
Slowly dissolves

Mass movement

Sliding of material through influence of gravity

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