Question | Answer |
Physical weathering = | Rock broken up in situ. Simply smaller bits of the same rock. No change to chemical makeup. |
Freeze-thaw 1) | Water gets trapped in joints/bedding planes & freezes. |
Freeze-thaw 2) | Expands (by 9%), putting pressure on the rock. |
Freeze-thaw 3) | If this happens repeatedly, the rock will weaken & shatter into angular fragments. e.g. Snowdon |
Freeze-thaw 4) | These fragments are deposited as scree. |
Exfoliation = | Happens in area with hot/dry climates. |
Exfoliation 1) | Heat causes outer layers to heat faster than inner layers. |
Exfoliation 2) | Expansion causes cracks parallel with the surface. |
Exfoliation 3) | Cooling causes contraction, producing cracks at right angles to the surface. |
Exfoliation 4) | Pressure on the lower rock is released, causing surface crack. |
Exfoliation 5) | Top layer eventually peels off. |
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