2.5B Depositional landforms

• Deposition = when waves no longer have sufficient energy to continue to transport material
• Depositional landforms:

  • beaches
  • bay head beach
  • spits (hooked/recurved)
  • double spits
  • offshore bars
  • tombolos
  • cuspate forelands
• beaches:

  • ccumulations of sand and/or shingle found in the foreshore and backshore zones. 
  • They're produced by material deposited by constructive waves
• Bayhead beach:

  • curved beaches found at the back of a bay.
  • They’re common on swash-aligned coastlines where wave refraction disperses wave energy around the bay perimeter.
• Spits:

  • linear ridges of sand or shingle beach stretching into the sea beyond a turn in the coastline but connected to the land at one end
  • form on drift-aligned coastlines, where the coastline changes direction
• Hooked/recurved spits:

  • spit whose end is curved landwards, into a bay or inlet.
  • A hook or a recurve may form at the end of the spit. 
  • Caused by wave refraction round the distal end transports and deposits sediment for a short distance in the landward direction. 
• Double spits:

  • where two spits extend out in opposite directions from both sides of the bay, towards the middle.

  
• offshore bars:

  • ridges of sand or shingle running parallel to the coast in an offshore zone. 
  • form from sediment eroded by destructive waves and carried seawards by backwash. 

  
• Bars/barrier beaches:

  • Linear ridges of sand/shingle extending across a bay and are connected to land on both sides. 
• tombolos:

  • linear ridges (or bar) of sand and shingle connecting an offshore island to the coastline of the mainland. 

  
• Cuspate forelands:

  • Low lying triangular shaped headlands, extending our from a shoreline, formed from deposited sediment. 

  
• Plant succession:

  • Depositional landforms are unstable because:
  • They are made of unconsolidated material
  • They are dynamic as they loose material transported by waves, tides, currents and wind.
  • stabilised by plant succession, which binds the loose sediment together and encourages further deposition.