There are 3 types of geographical processes for coasts;
- Erosion
- Transportation
- Deposition
Erosion
The sea shapes the coastal landscape. Coastal erosion is the wearing away and breaking up of rock along the coast. Destructive waves erode the coastline in a number of ways:
- Hydraulic action. Air may become trapped in joints and cracks on a cliff face.
- Abrasion. Bits of rock and sand in waves crush down cliff surfaces like sandpaper.
- Attrition. Waves smash rocks and pebbles on the shore into each other, and they break and become smoother.
- Solution. Acids contained in sea water will dissolve some types of rock such as chalk or limestone.
Transportation
Waves can approach the coast at a certain angle due to the direction of the wind. The splash of the waves carries material up the beach at an angle. The backwash then flows back to the sea in a straight line at 90°. This movement of material is called transportation.
There are various sources of the material in the sea. The material has been:
There are various sources of the material in the sea. The material has been:
- Eroded from cliffs
- Transported by longshore drift along the coastline
- Brought inland from offshore by constructive waves
- Carried to the coastline by river
Deposition
When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition. Deposition happens when the swash is stronger than the backwash and is associated with constructive waves.
Deposition is likely to occur when:
Deposition is likely to occur when:
- Waves enter an area of shallow water.
- Waves enter a sheltered area, for example; a cove or bay.
- There is little wind.
- There is a good supply of material.
Impacts
Severe storms are often accompanied by extended periods of heavy rainfall which can have significant effects on coastal processes. Extreme events, such as storms, and slow gradual changes often go unseen. The waves, water levels and winds, together with coastal currents and estuaries flowing into coastal waters, reshape beaches and shift beach sediments offshore, onshore and alongshore which defines that coasts interact with each other, often in quite complex ways.