2.1.4

Deposition

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Coastal Deposition

Coastal deposition describes the sea dropping sediment (or material) being carried by the water at the coastline. Coasts grow in size when more sediment is deposited on the coast than is lost to the process of erosion.

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Why does deposition happen?

  • Deposition happens when constructive waves break on the shore. The sediment being carried by the sea is put (deposited) on the coastline.
  • This usually creates beaches made of sand or shingle in the area between the 'high' water mark and the 'low' water mark.
  • The high water mark is the point the highest up the beach that the sea level rises to.
  • The low water mark is the point the lowest down the beach that the sea level falls to.
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Water marks

  • An image of high and low water marks.
Illustrative background for What increases the amount of deposition?Illustrative background for What increases the amount of deposition? ?? "content

What increases the amount of deposition?

  • If erosion on the nearby coast is high, then lots of rock and sand will fall into the ocean. This will increase deposition on nearby beaches.
  • The more sediment in the ocean, the more deposition there will be.
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Why are some beaches sandy & some shingle?

  • Sandy beaches are created by sand being deposited on the shoreline.
  • Sandy beaches are usually very long, wide, and flat because particles of sand are very small and easy to wash back into the ocean with the backwash.
  • Shingle beaches are made when pebbles and shingle are deposited on the coast. Shingle and pebbles are big and hard to wash back into the ocean, so they build up (making short and steep beaches).

Formation of Spits

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Spits

  • Spits can form at estuaries (where a river meets the sea).
  • The river doesn't let the longshore drift completely join the coast on the other side because the river has the energy to move the sediment.

Jump to other topics

1Paper 1 - Changing River Environnments

2Paper 1 - Changing Coastal Environments

3Paper 1 - Changing Ecosystems

4Paper 1 - Tectonic Hazards

5Paper 1 - Climate Change

6Paper 2 - Changing Populations

7Paper 2 - Changing Towns & Cities

8Paper 2 - Development

9Paper 2 - Changing Economies

10Paper 2 - Resource Provision

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