Sand Dunes

  • Created by: alana
  • Created on: 06-12-18 17:20
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  • Sand dunes
    • Optimum conditions
      • Large supply of sand
      • Flat beach gradient
      • Strong prevailing onshore winds - moves sand
      • Fine sand particles
      • Large area of beach exposed at low tide
    • Formation process
      • M - Every    M - Fancy   M - Yellow    F - Goose     F - Dances
      • Sand grains blown inland and transported by saltation (bounces and rolling)
        • Sand accumulates and builds upper beach height
          • Reduction in wind velocity behind accumulation= more sand deposition
            • Marram grass colonises EMBRYO DUNES stabilising further dune migration
              • Marram grass = tolerant of very sandy conditions. Stabilises sand movement
              • Marram leaves further reduce wind speed and capture blown sand. Decaying plants add humus.
                • Adjacent embryo dunes merge to form FOREDUNES
                  • Microclimate and soil conditions change allowing colonisation by additional species
                    • Mature YELLOW DUNES are formed. Eventually, GREY DUNES form a long way from sea and are fixed due to cover of vegetation
    • Landforms formed by sand deposits when the rate of erosion is smaller than the rate of deposition.

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