EES-1000 Lecture 11: Weathering.DOC
6 Nov 2016
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Mechanical weathering solid rock fragmented by physical processes. Chemical weathering disintegration of rocks by chemical processes. Mass wasting large scale collapse of hillslopes. Different materials weather at different rates (quartz vs. calcite) Cold, dry climates have little chemical weathering but may have high physical weathering. The water retained in the soil + organisms create an acid environment that promotes chemical weathering. *physical and chemical weathering are positive feedback processes. *dependent on surface area because chemical weathering only affects the surface of a solid. Occurs when minerals react with air and water: hydration (h20, addition of co2, oxidation (o2) *carbonic acid forms from co2 dissolved in water. Arkose indicates physical weathering > chemical weathering. Dark brown coating on desert rocks that consists of clay + fe-oxides. Exfoliation joints (aka onion skin weathering) form due to pressure release in. Nature of moving mass (flowing or sliding as distinct blocks). Creep slow downhill movement of unconsolidated material.
