Sub aerial weathering: Coastal processes

• What is weathering


  When material is broken down in situ, remaining in or near its original position
• What is physical weathering?

  The disintegration of rock, without any significant change in the chemical or mineral composition of the rock
• What is freeze wedging/freeze thaw weathering (physical )


  When water freezes in a rock crack and expands, resulting in pressure, causing the rock to crack and open
• What is salt crystallisation (physical)

  Water connects between cracks, evaporation leave salt crystals behind and rock eventually breaks apart
• What is insolation weathering/onion skin (physical)

  What day is result in outer part of rock becoming hotter than interior. At night lots of surface, he will reverse temp gradient. Heating + cooling leads to expansion + contraction
• What is surface unloading? (Physical)

  Rocks formed under pressure exposed to surface sudden pressure, changes, causes expansion of outer, newly exposed layers - causes joints to form at right angles to pressure release
• What is chemical weathering?

  The decomposition of rocks by the action of air, water or acid
• What is hydration? (Chemical)

  The chemical bonds of minerals are changed as it interacts with water
• What is hydrolysis? (Chemical)

  A new solution (mixture of two or more substances) is formed as chemicals in rock interact with water
• What is oxidation (chemical)

  Reaction that occurs between compounds and oxygen
• What is carbonation? (Chemical)

  When rain water hits rock it decomposes the rock when carbon dioxide from air reacts with carbonate minerals in rock
• What is solution? (Chemical)

  Many minerals are soluble + are removed when they dissolve in water
• Chemical weathering causes rock disintegration by:

  - weakening the coherence of minerals

  - dissolution + removal of minerals

  - mineral expansion through combination with oxygen or water
• What is biological weathering?

  The breakdown of rocks and minerals as a result of the activities of plants, animals and microorganisms