Formation of spits, tombolos and bars


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Formation of spits, tombolos and bars

  1. 1. By:Syazwani Ismail
  2. 2.  Spit is a long narrow ridges of sand and shingle which is projected into the sea from coastline
  3. 3.  Longshore drift transports material along the coastline Spits formed in shallow and sheltered water when there is a change in the direction of the coastline Deposition occurs resulting in the accumulation of sand and shingle The material initially deposited is the largest material, dropped due to the reduction in energy
  4. 4.  Finer material is then deposited, helping to build up the rest of the spit As spit grow outwards, a change in wind direction may result in a change in the direction of the spit forming a curved end (recurved laterals) If growing across a river estuary, the length of the spit will be restricted A salt marsh may form in the sheltered, low energy zone behind the spit.
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  6. 6.  a ridge of sand and shingle joining the mainland to an islandhttp://
  7. 7.  Tombolos are created through the process of longshore drift A tombolo is formed where the spit continues to grow until it reaches an island, forming a link with the mainland, just like bridges
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  9. 9.  a ridge of sand and shingle which has joined two headlands, cutting off a bay
  10. 10.  (a) a spit grows the whole way across a bay (b) a sandbank devlops offshore, parallel to the shore, and is moved towards the coastline by the waves and wind until it joins the mainland Behind the bar, a lagoon is created, where water has been trapped and the lagoon may gradually be infilled as a salt marsh Over time the lagoon will become infilled by deposition
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  12. 12. Features Spits Summary Tombolos BarsWhat is it? a ridge of sand and a ridge of sand and a ridge of sand and shingle projecting shingle joining the shingle which has from the mainland mainland to an joined two into the sea island headlands, cutting off a bayHow does it form? when there is a formed when spit (a)form when a break in the continue to grow spit grows the coastline and drop outwards whole way across a in energy, long- connecting the bay shore drift mainland to the (b) a sandbank deposited the offshore island just develops offshore, material and build like bridges parallel to the up spit shore until it joins the mainlandExample Hurst Castle Spit Isle of Portland Slapton Sands