Coastal Weathering and Erosion
Salt weathering - water evaporates leaving salt crystals, which can expand and fracture rock
Biological weathering - burrowing animals and roots from trees/plants can break up
Hydraulic action - waves trap air in cracks in the rock. Pressure of water and compressed air causes rock to crack
Abrasion - particles in waves crash againt cliffs and break bits off
Attrition - particles in waves crash against each other
Solution - seawater slowly dissolves cliffs
The process of transportation along coastal areas is called longshore drift. Longshore drift is the process of waves transporting material along a coastline. Longshore drift only occurs when waves hit the beach at an angle due to prevailing wind direction.
The swash 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.
Waves and tidal currents can also carry material through solution (dissolved minerals), suspension (small particles carried in water), saltation (load bounced along sea bed) and traction (load rolled along sea bed)
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.
It is likely to occur when:
- waves enter an area of shallow water
- waves enter a sheltered area, eg a cove or bay
- there is little wind
- there is a good supply of material