Physical CAUSES of coastal erosion

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  • Created by: Jes10
  • Created on: 28-10-17 05:00
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  • Physical causes of coastal erosion
    • Waves
      • Destructive or constructive
        • Destructive-steeper gradient waves have more energy and cause more erosion
          • These high powerful waves breaking at the foot of the cliffs are more damaging due to point at which energy is released
        • Constructive-gentle gradient on the waves so more deposition than erosion
      • Fetch is a factor that affects wave type
      • Three factors that affect wave type: Speed, Distance and Time
    • Geology
      • Lithology
        • Less resistant rock type faster rate of erosion e.g. clay
        • More resistant type of rock, slower rate of erosion e.g. granite
      • Structure
        • Different rock types run parallel to the coastline=CONCORDANT
          • The sea will only be able to break through the resistant rock in some places
        • Different rock types run perpendicular to the coastline-DISCORDANT
          • less resistant rocks are exposed and will erode more quickly but we will get different rates of erosion so HEADLANDS AND BAYS would start to emerge
    • Geomorphology
      • The shape of the coastline will affect the rate of erosion
        • Headlands cause wave refraction, making waves converge and combine their energy
          • Wider shallower bays allows waves to diverge losing energy due to friction with the sea bed
      • Beach Presence
        • Wider beach more wave energy lost due to friction
        • Narrower beach means breaking point will be closer to the coastline and less energy will be lost due to less friction
      • Beach material
        • Shingle and pebbles will allow more water to infiltrate and casue more wave energy to be lost due to friction
          • Because shingle and pebble beaches leave less energy for backwash, material tends to move upwards making the beach steeper and therefore encourages higher rates of erosion
        • Sandy beaches allow less infiltration and cause less friction and allow for a higher rate of erosion

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