Coastal Processes

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  • Created by: paddyk02
  • Created on: 08-06-16 21:36

Coastal Erosion

The sea shapes the coastal landshape. Coastal erosion is the wearing away and breaking up of rock along the coast. Destructive waves erode the coastline in a number of ways.

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Hydraulic action

Air may become trapped in joints and cracks on a cliff face. When a wave breaks, the air in the cracks is compressed which weakens the cliff and causes erosion

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Abrasion

Bits of rock and sand in waves grind down cliff surfaces like sandpaper.

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Attrition

Waves smash rocks and pebbles on the shore into each other, and they break and become smoother.

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Solution

Acids contained in the sea water will dissolve some types of rock like chalk or limestone.

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Longshore Drift

Waves can approach the coast at an angle because of the direction of the prevailing wind. The swash carries the material up the beach in the direction of the prevailing wind, and the backwash will carry the material back down the beach at a 90 degree angle. Continual swash and backwash transports materials sideways along the coast - this movement of material is called longshore drift and occurs in a zigzag shape.

1. Waves approach coast at an angle because of prevailing wind

2. The swash carries the material up the beach in the direction of the prevailing wind

3. The backwash carries the material back down the beach at a 90 degree angle

4. The process continues to occur

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Spits

Spits are created by deposition. A spit is an extended piece of beach materail that projects out into the sea and is joined to the mainland at one end. 

Spits are formed when the prevailing wind blows at an angle to the coastline, resulting in longshore drift. 

1. Longshore drift moves material along the coastline

2. A spit forms when the material is deposited

3. Over time, the spit grows and develops a hook if wind direction changes further out

4. Waves cannot get past a spit, which creates a sheltered area where silt in deposited and mud flats or salt marshes form

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