sand dunes

• sand dunes are examples of deposition
• sand dunes

  large heaps of sand formed on the backshore of a beach
• examples of sand dunes

  studland bay, dorset
• characteristics of sand dunes:

  • unstable, steep slope on the sheltered, leeward slide (away from sea)
  • crests
  • gentle slope on windward slide (facing the sea)
• stage 1

  sand moves up the windward slope
• stage 2

  height builds up until the structure becomes unstable
• stage 3

  sand then slips down the leeward slope
• a sand dune needs

  • a large flat beach
  • a large supply of land
  • a large tidal range
  • an onshore wind to move sand up the beach
  • an obstacle such as drift wood for the dune to form against
• what is this a picture of?

  sand dunes

  
• label this diagram

  hey

  A) obstacles

  B) wind blows sand which is trapped

  C) plants grow on dune to stabilise the dune

  D) creates embryo dune

  
• label this diagram

  boo

  A) embryo dune

  B) fore dune

  C) yellow dune

  D) grey dune

  E) dune slack

  F) mature dune

  
• embryo dunes are only a few metres high
• size of dune increases inland as plants grow bigger and trap the sand in the dune
• dunes close to the sea have a more yellow colour compared to the dunes further back which are grey
• the dunes become increasingly colonised by vegetation inland
• each line of dunes is separated by a trough called a slack