AQA AS Geography Coasts: Mindmap 3

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  • Physical geography
    • Geomorphological processes: anything that affects the landscape
      • Weathering, mass movement, erosion, transportation and deposition.
        • Coastal marine processes: erosion, transportation and deposition.
        • Sub aerial processes: weathering, mass movement and run off.
      • Coastal marine processes: erosion, transportation and deposition.
      • Sub aerial processes: weathering, mass movement and run off.
    • Sub aerial processes: mass movement
      • Mudflow occurs of steep slopes over 10 degrees. It's a rapid movement which occurs after heavy rain. When there isn't enough vegetation yo stabilise it, saturated clay flows out of the cliff face like a river of mud.
      • Landslips or rotational slumps are occasional rapid movements of earth or rock dropping down along a concave plain. Water percolating through sandstone gets into the clay beneath, saturating it. The clay then moves seawards as mudflow as a result of the weight above it.
      • Rockfall is the freefall of rock from a steep slope due to gravity. It is worsened by freeze thaw weathering. A scree slope of fallen rock is formed at the bottom of the cliff.
      • FACTORS THAT AFFECT SEED OF PROCESSES: steepness of cliff; climate (rain acts as lubricant); vegetation (plants stabilise soil and absorb water as well as slowing down movement of debris)
      • Soil creep is a very slow movement occurring on very gentle slopes. When wet, soil particles expand and become heavier. When dry, the particles contract vertically. As a result, the soil slowly moves downhill.
      • Landslides are when a block o frock moves rapidly along a slide surface. Material remains largely intact. This is largely triggered by heavy rainfall.
      • Solifluction is similar to soil creep but in cold environments. In summer, the layer of soil thaws out, becoming saturated as it lies on top of impermeable frozen ground. The sodden soil then slowly moves downhill.
    • Transportation processes
      • Traction: large material; rolled along sea bed; too heavy to be carried by sea.
      • Saltation: beach material; bounced along sea bed; too heavy to remain afloat.
      • Suspension: smaller beach material; carried in water; suspended by waves.
      • Solution: dissolved material; carried by water.
    • Geomorphological processes and coastla marine processes: Erosion
      • Hydraulic action, attrition, abrasion, solution
    • Longshore drift
      • As a result of the prevailing winds, the swash moves sediment in this same direction. The backwash, under gravity, pulls the material back down the beach at right angles tot he coastline. Over time, this results in a net shift of material along the coast.
    • Estuarine mudflats and salt marshes
      • As mudflats develop, salt tolerant plants begin to colonise and stabilise them. Halophytes help to stop tidal flow and trap more sediment ans silt. As sediment accumulates, the surface becomes drier.
        • Creeks (created by water flowing across an estuary at low tide) divide up the salt marsh.
        • The process of flocculation involves tiny mud particles sticking together until their combined mass causes them to sink. This results in deposition.


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