depositional landforms

• what is a barrier beach

  when a beach extends across a bay to join 2 headlands, they often lie parrallel to the coastline and are sperated by body of water from the mainland forming a lagoon
• example of a barrier beach

  - slapton sands in devon

  - 1.5 miles long and is connected to rivers and streams

  - formed due to the rise in sea levels after the last glacial period
• what is the role of a brrier beach

  • provide natural protection to wetland
  • act as natural coast defences as they protect against flooding + erosion
• what is the formation of a barrier beach

  1. longshore drift: waves approach the beach at an angle causing sediment to be transported along the coast
  2. spit formation: sediment accumulates forming a spit
  3. barrier beach: when a spit grows and connects to an opposite headland a barrier beach forms
  4. lagoon: the area behind the beach forms a lagoon
• how was slapton sands formed

  1. depostional processes due to sea levels rising
  2. longshore drift deposited material forming the barrier beach
  3. destructive waves removed sediement from the beach to form an offshore bar
• barrier island

  when the beach is seperated from its mainland
• what is a tombolo

  • a tombolo is a beach that has formed between a small island and the mainland
  • deposition occurs when waves loose energy and the tombolo begins to build up
• example of a tombolo

  Chesil Beach in Dorset, England
• how do tombolos form

  1. The process of longshore drift occurs and this moves material along the coastline.
  2. Material is pushed up onto beaches at an angle when the swash brings it onto the coastline at a 45 degree angle. The backwash takes it back out towards the sea at a right angle to the coast.
  3. material is constantly moved along the coastline
  4. When the coastline changes direction or there is a river estuary the process of longshore drift continues. This causes material to be deposited forming a spit. 
  5. If the spit moves in the direction of island and connects it to the mainland then it becomes a tombolo.
• what is a cuspate foreland

  • a triangular shapes headland which extends out from the main coastline
• how does a cuspate foreland form

  1. Waves approaching the coastline at an angle cause sediment to be transported along the shore. This is known as longshore drift. 
  2. When longshore drift from opposite directions meets, the sediment carried by both drifts is deposited. 
  3. As the sediment is deposited, it builds up, eventually forming a triangular or cusp-shaped landform extending out from the shoreline.
  4. as vegetation begins to grow it helps stablaise the lanform and protect it from storms
• example of a cuspate landform

  Dungeness in kent
• what is a sandune

  A sand dune is a mound or ridge of sand, typically found along a beach or in a desert, formed by the wind.
• how are sand dunes formed

  • when sand is blown off the beach by onshore winds.
  • vegetation helps stablaise the dunes as a result of plant recession
• what are the 5 stages to sand dunes

  1. strandline
  2. embryo dune
  3. mobil dune
  4. semi fixed dune
  5. fixed dune
• example of sand dunes

  camber sands, east sussex, england
• what is a spit

  a long narrow faeture made of sand or shingle which extends from the land to the sea
• how are spits formed

  1. lonshore drift: Waves approach the beach at an angle, causing sediment to be moved along the coastline in a zig-zag pattern. 
  2. When the coastline changes direction the longshore drift continues to move material, but it no longer has the straight path
  3. The sediment is deposited in the sea where the coastline bends, building up a ridge of material. 
  4. Over time, the deposited material builds up until it forms a long, narrow landform that extends out into the sea.
• example of a spit

  Spurn Head, located north of the Humber Estuary in the northeast of England
• whats is a beach

  A beach is a narrow, gently sloping strip of land that lies along the edge of an ocean, lake, or river
• how do beaches form

  Beaches are made up from eroded material that has been transported from elsewhere and then deposited by the sea. For this to occur, waves must have limited energy, so beaches often form in sheltered areas like bays. Constructive waves build up beaches as they have a strong swash and a weak backwash.
• whats the difference between a swash alligned and drift aligend beach

  • swash aligend: sediment moves up and down with the tide with little lateral transfer
  • drift aligned: sediment is moved along the coast by longshore drift
• example of a beach

  Camber sands, east sussex england
• what are tides and currents

  • tides: Tides are very long-period waves that move through the ocean in response to the forces exerted by the moon and sun. 
  • currents: a steady predictable movement of fluid within a larger body of fluid
• what is the difference between high and low tides

  • differnece is callled a tidel range
  • a high tidal range causes powerful tidal currents as tides rise and fall - finer sediemnt deposited on higher parts of the beach eg clay
  • low tidal range is when the sea is at its lowest level during low tide -smaller sedimenst deposited on lower parts of the beach eg salt and gravel
• what is a salt marsh

  an area of flat, sility sediments that accumalte around esturies or lagoons
• where do salt marshes develop

  sheltered areas where deposition occurs, where salt and freshwater meet and where there are no strong tides or currents to prevenet sediment deposition or accumlation
• how are salt marshes formed

  when mud and silt are deposited along a sheltered part of the coastline due to deposition rates being greater than transportation rates becasuse of lack of energy in waves
• what happens when deposition builds up overtime on a salt marsh

  plants such as cordgrass begin to grow. these plants are tolerant to sea water and its long roots help hold mud and sediment together
• what are the different zones of a salt marsh

  1. pioneer stage: mud flats and cordgrass#
  2. low marsh stage: marsh elevation increased flloding
  3. high marsh stage: high elevation + less flooding
  4. transition to terrestial vegetation: less frequently flooded and soil becomes more stable
• example of a salt marsh

  Morecombe bay in north west england