Theory question 304
Weathering, Erosion and Mass Movement(a) Define weathering. (b) Identify three factors that affect weathering. (c) Describe the processes of exfoliation.
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(a) Weathering is the breakdown or decay of rocks in their original position (in situ) by physical, chemical or biological processes, without the material being moved.
(b) Climate (temperature and rainfall); rock type and mineral composition; rock structure (joints, bedding planes); relief/slope; vegetation and living organisms; human activities; time.
(c) Exfoliation (onion weathering): in hot deserts rocks are heated strongly by day and cooled quickly at night; rocks are poor conductors, so the outer layer expands and contracts more than the inside; repeated stress creates cracks parallel to the surface; the outer shells peel off like the layers of an onion; moisture from dew can speed it up; it leaves rounded rock masses (exfoliation domes).
Stress repeated heating and cooling.