Theory question 205
Weathering, Erosion and Mass Movement(a) Define the term weathering. (b) Describe four processes of chemical weathering.
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(a) Weathering is the breaking down or decay of rocks in their original place (in situ) by physical, chemical and biological processes, without the material being carried away.
(b) Carbonation: rainwater with carbon dioxide forms weak carbonic acid that dissolves limestone; oxidation: oxygen in water combines with iron in rocks, forming rust-coloured iron oxide that crumbles; hydration: minerals absorb water, swell and break up (e.g. feldspar to kaolin); hydrolysis: water reacts chemically with minerals such as feldspar in granite to form clay; solution: soluble minerals such as rock salt dissolve directly in water.
Name the rock or mineral affected by each process.