Coastal change and conflict

Coastal Change and conflict.

Erosion.

Hydraulic Action.

When the pressure of the water is thrown against the cliff face. This forces compressed air and water into the cracks causing mini explosions.

Corrasion/Abrasion.

When sand and pebbles are thrown against the cliff face by the waves. These particles break off material which is then, in turn, thrown against the cliff face.

Corrosion/Solution.

 Is when a chemical reaction occurs between certain rock types, salt and carbonic acid. This mostly affects limestone and other sedimentary rocks, where the water is milky blue, which is the dissolved limestone.

Attrition.

Is the wearing away of rocks. As the stones and boulders roll around, they clip away at each other until smooth pebbles or sand is created.

Swash.

This is when the wave goes up the beach in the prevailing wind direction.

Backwash.

This is when the wave is pulled by gravity down the beach at a 90 degree angle to the coastline.

Constructive waves.

These have a strong swash and a weak backwash. They are low in height and long in wave length. They occur on gently sloping beaches. Deposition is greater than erosion.

Destructive waves.

These are a tall breaker, they break downwards with a great force. They are a high wave in proportion to length. They have a weak swash and a strong backwash. The rate of erosion is greater than the rate of deposition.

Weathering.

Chemical weathering.

When rock reacts with the air and water.

Physical weathering/ freeze thaw weathering.

Water enters cracks in the rock then freezes and expands breaking up the rock.

Biological Weathering.

Roots grow into cracks and widen them. It can also be when houses are build on top of cliffs or people and cars cause vibrations weakening the cliff.

Onion- skin weathering.

Rock expands when it is heated (e.g. by the sun) and contracts when it is cool. This continual expanding and contracting weakens the rock and layers peel off, like peeling layers off an onion.

Caution!

Erosion and weathering are not to be confused or used interchangeably. Erosion takes place at the cliff foot due to wave action. Weathering takes place higher on the cliff face and is chiefly cause by the weather as well as biological activity.

Longshore Drift.

This is the movement of sediment up the beach. The waves break at an angle to the coastline depending…