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Geomorphic processes, Geomorphic processes - Coggle Diagram
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Geomorphic processes
Erosion
Solution: the dissolving of soluble rocks, such as chalk and limestone.
Hydraulic action: this involves the sheer power of the water, often compressing air into cracks in sea cliffs or river banks, causing rock to break away.
Erosion involves the wearing away and remove of material by a moving force, such as breaking wave. The main processes of erosion are abrasion, hydraulic action, attrition and solution.
Abrasion: This is the 'sandpapering' effect as loose rock particles carried by the water scrape against solid bedrock. It can involve loose particles being flung against a sea cliff or river bank by the water - a process sometimes referred to as corrasion.
Attrition: erosion caused when rocks and boulders transport by waves bump into each other and break up into smaller pieces. Over time the rock become smaller and more rounded.
Weathering
Mechanical weathering
Salt weathering - crystals of salt, often evaporate from seawater, grow in cracks and holes, expanding to cause rocks fragments to flake away.
Freeze-thaw - repeated cycles of freezing and thawing causes water trapped in rocks to expand and contract, eventually causing rock fragments to break way.
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Chemical weathering
Carbonation - carbon dioxide dissolved in rainwater forms a weak carbonic acid; this reacts with calcium carbonate (limestone and chalk) to form calcium bicarbonate, which is soluble and can be carried away by water.
Hydrolysis - acidic rainwater reacts with feldspar in granite, turning it into clay and causing granite to crumble.
Oxidation - oxygen dissolved in water reacts with iron-rich minerals, causing rocks to crumble.
A third type of weathering is biological weathering, involves living organisms such as nesting birds, burrowing animals and plants roots. Plants roots may expand in cracks, slowing prising rocks apart. Acids that promote chemical weathering may be active beneath soils and rotting vegetation.
Weathering involves the decomposition or disintegration of rock in its original place at or close to the ground surface. There are two main types of weathering: chemical weathering and mechanical (physical) weathering.
Mass movement
Mass movement is active at the coast, particularly where cliffs are undercut by the sea, making them unstable. It includes sliding and slumping, as well as fall (rockfalls) and flow (mudflows).
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Sliding - this involves rock or loose material sliding downhill along a slip plane, such as bedding plane. Slides are often triggered by ground shaking (for example, an earthquake or heavy rain.
Slumping - this involves the collapse of weak rock, such as sand and clays, often found at the coast. slumping often results from heavy rainfall when the sediments become saturated and heavy.
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Deposition
Deposition occurs when material being transported is dropped due to a reduction in energy. This typically occurs in areas of low energy, where velocity is reduced and sediments can no longer be transported. At the coast, disposition is common in bays or in areas sheltered by bars and spits. In rivers, deposition is common clos to the river banks, in estuaries and at the inside bend of meanders.
