ocr geo how are coastal landforms developed

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  • How are coastal landforms developed - ocr alevel
    • Weathering
      • physical/ mechanical
        • salt crystallisation:  salt solutions   can sink into the spaces in porous rocks. salt forms crystals, the growth of these crystals causes the rock to disintegrate
          • pressure released: when overlying rocks are moved by weathering and erosion the underlying rock expands and fracture
      • Chemical
        • carbonation: rainwater combines with dissolved co2 to produce a weak carbonic aside that reacts with rocks such as limestone making them soluble
          • hydration: water molecules added to rock minerals  create new minerals of a larger volume. hydration causes surface flaking in many rocks
      • Biological
        • tree roots: tree roots grow into cracks or joints in rocks and exert outward pressure. significant on cliff tops and faces
          • organic acids: organic acids produced during decomositionof plant and animal litter cause soil water to become more acidic and react with some minerals
    • mass movement
      • Rock fall: on cliffs 40 degrees or more, especially if the cliff face is bare rocks may become detached by physical weathering processes
      • slides: undercutting by wave erosion at the base of the cliff which removes support for the material above
    • wave processes
      • Erosion: abrasion (rocks rubbing), attrition (rocks colliding)  , hydraulic action (waves break on cliff face), solution (dissolved minerals) , pouding (breaking wave exerts pressure on rocks)
      • transportion: solution (dissolved minerals), suspension (small particles carried by current), saltation (suspension), traction (dragged along sea floor)
    • Deposition
      • where the rate of sediment exceeds the rate of removal
      • when waves slow down right after breaking
      • in low energy environments
      • during backwash when water percolates into the beach material

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