Depositional features - Beaches

• Wave refraction

  1. Wind blows waves towards an irregular shoreline with bays and headlands

  2. Different parts of the wave will feel the influence of the bottom or seas floor at different stages

  3. Directly offshore of headland. The wave will slow down and travel less far

  4. But offshore from a bay, the wave will still be in deep water and so travel further

  5. As a result, wave and energy is concentrated on both sides of a headland, causing erosion

  6. But wave energy is dispersed across a bay, meaning deposition

  7. The overall effect is that the wave ends to almost match the shape of the coastline

  8. Lastly, because the waves never quite match the shape of the shoreline we still get the process of erosion (hydraulic action)
• Ripples


  Happens when the tide goes out meaning the waves retreat creating patterns in the sand. Only happens at low ride
• Tunnels

  Natural ditches of water between ridges and the beach. Quite shallow, only visable in low tide
• Ridges

  Form due to deposition of sand from waves. Which builds up creating a raised area. Only visible at low tide
• Off-shore bars

  Deposits of sand off-shore, not visible at a low tide as it's too low. Beach gets turned into off-shore bare mainly in winter due to storms eroding the beach.
• Cusps

  Naturally formed semi-circle formed in bays as wave refraction is bent, causing energy to spread out. Divided the wash and come into contact with another wash creating a stronger backwash.
• How are beaches formed?

  Beaches form in sheltered, low energy environments, such as bays. When swash stronger than backwash, deposition occurs.
• Swash-aligned Beaches:


  Tend to form in low energy areas such as bays that are affected by waves arriving roughly parallel to the shores.
• Drift-aligned Beaches:

  Form where waves approach the coast at an angle, long shore drift moves sediment along the beach often culminating in the formation of a spit.
• Main features of a beach.

  Cliff

  Bedroot

  Onshore zone back shore

  Foreshore

  Nearshore

  Offshore

  Storm berm

  Pebbles

  Berm

  Sand runnels and ridges

  Long shore bars

  Max spring tide

  High tide

  Low tide

  Breakpoint bar.