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Weathering 05.12.18 (force and resistance a balance (Force types (Tensile…
Weathering 05.12.18
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Weathering types
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Mechanical weathering
Wave abrasion, wave quarrying, joint block removal. (mass amounts of weight and force against rock- removal too)
Erosion/ surface lowering is measured by a MEM (Micro Erosion Meter) looking at changes in topography. Sub mm scale.
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biological
Biophysical- root pressures, growing stress, wetting and drying, mechanical boring
Biochemical- Bacterial redox, growing chemistry changing stability, cation exchange.
Indirect- soil mixing, production of organic acids, organic protection layer.
Chelation- some organisms e.g. lichens can produce chelation compounds (organic acids which form a bond round metal ions.
why study weathering?
soil formation- important driver of soil formation, which is the basis for mud, global productivity and sustaining human life.
Landscapes, landforms- plays an important role in landscape evolution, it creates landforms and helps weaken rocks to make erosion easier.
structural engineering- durability of rock important for building and finding resources, weathering studies critically manage this.
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what is weathering?
The response of materials which were in equilibrium within the lithosphere but are now at or near the atmosphere, hydrosphere or biosphere.
weathering is the process that allows equilibrium to be reached again. Rocks want to be in equilibrium- least energy strain.
Breakdown and alteration of minerals near the earths surface to products that are more in equilibrium with the newly imposed conditions. turning rocks into sediment- their constituent parts, in situ. erosion is the process by which the weathered material is transported and reworked.
DENUDATION- removal of rock in the form of sediments form land- generally high relief to areas of low relief (elevation)
Weathering is caused by more than one weathering process- however, over time one process may become more important than the other.
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