Transportation Deposition


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Transportation Deposition

  1. 1. <ul><li>Why do we get beaches? </li></ul><ul><li>How is material transported? </li></ul>
  2. 2. <ul><li>The sea transports massive amounts of rock material around every day </li></ul><ul><li>Some bits are as small as sand, other bits are big pebbles or even boulders </li></ul>
  3. 3. <ul><li>Coasts are not just eroded, they are also built up by deposition – this is when eroded material is dropped off and builds up over time </li></ul><ul><li>This creates beaches </li></ul><ul><li>Deposition happens when waves are constructive (so the swash is bigger than backwash so material gets moved up on to the beach). </li></ul><ul><li>Material is moved by the sea and can travel miles </li></ul>
  4. 4. <ul><li>Longshore drift (LSD) is the process where waves transport eroded material along a beach and deposit it down coast </li></ul><ul><li>LSD animation </li></ul>
  5. 7. <ul><li>Geog.GCSE p92 </li></ul><ul><li>Make your own copy of the LSD diagram, with labels </li></ul><ul><li>Q)What controls the direction of movement along a beach? </li></ul><ul><li>Q)What direction does most material move on the south coast of England? </li></ul>
  6. 8. <ul><li>P93 </li></ul><ul><li>Q) Why is LSD sometimes a problem? </li></ul><ul><li>Q) What do we do to stop LSD? </li></ul>
  7. 10. <ul><li>Beaches, spits, bars and tombolos are created by deposition and transportation </li></ul><ul><li>Beaches are basically eroded material that has been transported from somewhere else and deposited </li></ul>
  8. 11. <ul><li>P94-95 </li></ul><ul><li>Write your own summary (just a few sentences) to explain: </li></ul><ul><li>- beaches </li></ul><ul><li>- spits </li></ul><ul><li>- bars </li></ul><ul><li>- tombolos </li></ul><ul><li>Extension: Answer Q1,3 </li></ul>
  9. 13. <ul><li>Revision games: </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li>Find some pictures of beaches, bars, spits and tombolos to stick in to your book. </li></ul>
  10. 14. Beaches develop when the supply of sediment exceeds any sediment lost through backwash and longshore drift. Beaches are usually distinguished as either … Shingle or Sand Shingle beaches are free draining so there is little backwash of material to sea. As a consequence, they are usually steeper.
  11. 15. Some features of a shingle beach .. ... The largest material is found furthest from the sea Successively lower berms You get ridges across the beach called berms
  12. 16. Sand beaches have a more gentle profile. This is because.... Wet sand compacts, so water doesn’t drain through it. This means that backwash, and the material it is carrying, is able to return to the sea. Sand is smoother than shingle.... so there is less friction to prevent the materials moving back down the beach
  13. 17. These get colonised by grasses and become ecosystems As on-shore winds blow across dry beach sand, it carries material inland to form sand dunes
  14. 18. Spits and Bars Where there is a change in the coastline e.g. a headland or an estuary mouth, longshore drift may continue to deposit sediments into the sea forming a spit.
  15. 19. Spurn Head at the mouth of the Humber estuary is a fine example of a spit.
  16. 20. Local currents and changes in wind direction may curve the end of the spit landwards creating a hooked tip. The presence of the estuary discharging river water into the sea prevents the spit from developing into a bar. Such a feature is known as a recurved spit wind
  17. 21. If a spit joins on to one part of the mainland to another it is called a bar .
  18. 22. For example, there is a bar at Slapton Sands in Devon.
  19. 23. Tombolo Where a spit joins the mainland to an island a tombolo may be created . The longest and best known tombolo in Britain is Chesil Beach .
  20. 24. Chesil Beach viewed from the Isle of Portland