coasts

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  • coasts
    • types of waves
      • constructive
        • .occur in calm conditions
        • have lower energy
          • they deposit matiriel
        • help transport matiriel
        • have a grater swash than backwash
      • destructive
        • they erode
        • occur in stormy conditions
        • have a large fetch
        • have a greater backwash than swash
    • mass movement
      • slumping
        • the base of the cliff is eroded by the sea
        • the top is saturated with rain
        • the cliff starts to slide
      • rock fall
        • fragments of rock break from the cliff due to weathering
        • bits of cliff fall to the base of the cliff
    • headlands and bays
      • hard rock like chalk is more resistant so isn't eroded as easily
        • this causes headlands
      • soft rock like clay is less resistant so is eroded easily
        • this causes bays
    • caves arches stacks and stumps
      • hydraulic action forces air into cracks causing erosion
        • a cave is formed from gradual erosion
          • overtime the waves erode the cave all the way through
    • depositional landforms
      • longshore drift
        • beach sediment is transported along the coast by waves
        • the waves swash forces the sediment up the beach at a 45 degree angle
        • the backwash will bring the sediment back down the beach at a right angle
        • the direction of prevailing wind will dictate the angle and direction that the sediment will move
      • spit
        • the materiel moves along the coast due to long shore drift
        • overtime the spit builds up as more sediment is deposited
        • the spit may curve at its end due to the direction of wind and waves
        • the spit creates a saltmarsh because the spit protects the area behind from wave action
      • bar
        • the materiel between two headlands build up
        • it grows across a bay
        • joins two headlands
    • coastal flooding
      • causes
        • high tide levels
        • storm surges
        • the action of waves
        • sea levels rising from global warming
      • reducing the impact
        • prediction eg the environment agency
        • prevention (barriers to protect against high tides and flood walls)
        • planning (early warning systems , flood education , escape routes)
    • coastal protection
      • hard engeneering
        • sea wall eg hornsea (protects cliffs and buildings but its expensive)
        • groynes eg hornsea (cheap but can ruin other coastlines)
        • rip rap eg mappleton (rocks absorb wave energy and they are cheap)
        • offshore reef (waves break on the reef and lose power but they are expensive)
      • soft engeneering
        • beach replenishment(cheap and sand reduces wave energy)
        • managed retreat (people avoid erosion but it is expensive)
        • cliff regrading (reduces slippage but the cliff still needs protection)

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