LANDFORMS

• two types of beaches

  shingle and sand
• what is a shingle beach?

  steep and narrow beaches formed from large particules
• what is a sand beach?

  wide and flat beaches , formed from smaller particules
• when do beaches form?

  when constructive waves deposit sediment on the shore
• two types of spits

  simple and compound
• what's a simple spit?

  an acculmation of sediment that is straight and runs parallel to the coast
• what's a compound spit?

  has recurved ends due to prevailing winds
• what forms behind a compound spit?

  mudflats and salt-marshes due to are being sheltered from waves
• when do spits form?

  when longshore drift deposits sediment across the river mouth , leaving a bank of sand and shingle sticking out to sea
• what is a tombolo?

  a bar that connects shore to an island
• what forms behind a bar?

  a lagoon
• how do bars form?

  they form when a spit joins together two headlands. This can occur across a bay or a river mouth
• whats an offshore bar?

  A bar located on a beach away from the mainland. They form off coast when material moves the coast as sea level rises - remain partially submerged by the sea
• example of a barrier island / beach

  Horn Island in Mississippi
• what are barrier islands?

  long , narrow islands of sand or gravel that run parallel to the shore - detached from shore
• how do barrier islands form?

  form in areas with good supply of sediment , gentle slope offshore , powerful waves and a small tidal range
• 1 theory of formation for barrier islands

  that islands were orginally bars attached to coasts (which had been eroded in sections) , causing breaches in bars
• 1 formation theory for barrier islands

  • formed after last ice age ended when ice melt caused rapid sea level rise
  • rising waters flooded land behind beaches and transported sand offshore
  • sand is deposited in shallow water and it forms islands
• things sand dunes need for formation

  • constructive waves
  • large supply of sand
  • high intertidal range
  • obstacle e.g driftwood
  • strong winds
• outline the processes leading to the formation of a barrier beach

  • longshore drift moves sediment along the coastline until there is a change in prevailing wind direction
  • spit develops - forms across whole bay = barrier beach forms
  • colonisation by vegetation can stabilise a barrier beach and trap further sediment keeping the barrier beach above the sea even at high tide
• explain the development of saltmarsh environments

  salt marshes develop in a sheltered estuary behind a spit. As the spit develops, the area behind it becomes developed.

  • silt is deposited by the river which gradually builds up to form an intertidal mudflat (silt mixes with water when tide comes in)
  • mudflat continues to build and rise above sea level with addition of further silt
  • vegetation such as halophytic vegetation colonises the mudflat which traps further sediment
• outline the features of a Dalmatian coastline

  Dalmatian coastlines are unique landforms of coastal submergence - they are named after the Croation Adriatic coastline

  • they were formed by changes to the volumes of water in oceans where fold hills and hence valleys lie parallel to one another.
  • when the valleys are flooded , the tops remain above sea level = appear as a series of long islands parallel to the coastline
  • seperated by narrow sea channels called sounds