Weatherin2 - wasting and erosion; reduces strength...

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Weathering the set of exogenic (physical, chemical and biological) processes that alter the physical and chemical state of rocks at or near the earth's surface intensity of most weathering decreases with depth, because variations in temperature and moistures decrease with depth therefore biochemical weathering is generally confined to the uppermost few metres of soil and rock occurs in situ (nontransported alteration), unlike erosion which removes soil and weathered rock; although the 2 sets of processes proceed simultaneously with positive feedback the 2 forms of weathering act simultaneously and affect the nature and rate of one another: disintegration produces an increase in rock surface area while changes in strength with changes in composition Functions of weathering 1. gives rock lower strength and greater permeability, rendering it more susceptible to mass
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Unformatted text preview: wasting and erosion; reduces strength (cohesion and friction) and increases permeability of rock and therefore decreases resistance to fluid and gravitational stresses; precursor to erosion 2. produces minor landforms, produces landforms in soluble rock (especially limestone) and otherwise creates microrelief (e.g. weathering pits) 3. releases minerals in solution (e.g. iron oxides, silica, carbonates) which become concentrated to form hard coatings on rocks and hard resistant layers in soil (duricrusts) that inhibit seepage and resist erosion 4. first step in soil formation; ultimately produces an unconsolidated mass of 1) minerals that resisted alteration (e.g. feldspar), 2) new minerals (e.g. bauxite), 3) organic debris...
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