Coastal Landscapes

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Coastal Landscapes

• Introduction

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• The sea, just like rivers and ice is a very
  powerful agent of erosion.
• It erodes a variety of landforms, and just like
  all agents of erosion, it also transports the
  material it erodes and makes new landforms where
  it deposits this material.

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Processes of coastal erosion

• Waves that have a lot of energy are able to erode
  the land at the coast.
• Waves erode the land by three main processes.
• Hydraulic action, Corrasion and solution.

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Hydraulic Action

• This is the sheer power of the waves smashing
  against the cliffs, compressing the air in its
  cracks, which makes the cracks wider and longer
  until pieces of rock break off.

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Corrasion

• This is when the sand, shingle and pebbles that
  waves are carrying are hurled against the cliff,
  causing pieces of rock to eventually break off.
• The rocks that break off the cliff and lie on the
  beach are then picked up by other waves and used
  to corrade the cliff even more.
• The rocks themselves are broken up into smaller
  and more rounded pieces.

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Solution

• This occurs as salt and other chemicals in the
  sea water slowly dissolve minerals in the rocks,
  causing them to break up.

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Processes of Coastal deposition

• The coastline of the British isles is being worn
  away, but this does not mean that our land will
  eventually disappear.
• The material that waves erode is deposited and
  builds up land elsewhere.

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• Waves deposit in areas where they have very
  little energy.
• They deposit the largest particles first, so the
  material is sorted according to size.

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Processes of coastal transportation

• When a wave breaks near the shore and washes up
  the beach this is called swash.
• When it runs back down the beach and back into
  the sea, it is called backwash.
• Along many of our coastlines the swash travels up
  our beaches at an angle.

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• As it has some energy it picks up sand and
  shingle and takes them up the beach.
• Backwash returns to sea down the steepest slope.
• The backwash carries the sand and shingle with
  it.

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• The swash from the next wave then picks the same
  particles up and repeats the process.
• In this zig-zag way sand and shingle are
  transported along the beach.
• The process is called longshore drift and it
  takes place in the direction of the prevailing
  winds.

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Longshore Drift
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Questions

• 1) Describe the 3 processes by which waves erode.
• 2) Waves deposit sorted particles. What does
  this mean?
• 3) What is the difference between swash and
  backwash?
• 4) What name is given to the movement of sand
  along a beach?
• 5) Using a diagram, explain how material is moved
  along a beach.