Geomorphic processes

Weathering

Weathering is the breakdown of material in the place they were found (in situ: without being transported) by mechanical (physical), chemical and biological processes.

  • Mechanical weathering– the physical actions of rain, frost and wind that create weaknesses in rocks.
  • Chemical weathering– minerals can react chemically in different ways, which weakens them. For example, water can react with some rocks to break them down, and air can weaken minerals through a process called oxidisation.
  • Biological weathering– rocks and land can be broken down by the actions of living organisms such as plants and animals, for example, rabbits burrowing into river banks.
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Mass movement

Mass movement is when material moves downhill; due to the pull of gravity. Gravity is an important force, as a ny steep slope or cliff will be constantly put under stress by processes which try to make it fall down. Other forces help to keep the feature standing, but given enough time, gravity usually wins.

  • Sliding – where a section of land falls down a slope and dislodges other material on its way down.
  • Slumping – where material at the bottom of a slope moves outwards.
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Erosion

Erosion is the wearing away of materials by a moving force, such as a river, waves, ice or wind, which take the material away.

  • Abrasion (also called corrasion) – when sediment is thrown against a surface by water and rubs the material to smooth the landform.
  • Hydraulic action – where water forces its way into cracks, which creates weaknesses in rocks, splitting them apart.
  • Attrition – where pebbles hit each other or landforms, making rocks break and get smaller and rounder.
  • Solution (Allso called corrosion) – where rocks are are dissolved in water.
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Transport

Transportation is the movement of material along the coast by waves, or along a river bed by the river.

  • Traction – the movement of larger sediment rolling the bottom of the sea or a river.
  • Saltation – small pieces of sediment picked up temporarily in the water.
  • Suspension – smaller particles can be suspended in water.
  • Solution – when minerals dissolve in water
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Deposition

Deposition is the laying down of materials that have been transported and can create new landforms such as beaches.

Deposition occurs when the material being transported is dropped due to a reduction in energy. This typically occurs in areas of low energy, where velocity is reduced and sediment can no longer be transported. At the coast, deposition is common close to the river banks, in estuaries and at the inside bend of meanders.

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