Coastal Deposition
Coastal Deposition is when the sea drops or deposits material. This can include sand, sediment and shingle.
The beach is the area between the lowest spring tide level and the point reached by the storm waves in the highest tides. Every beach is different but they are usually made up of material deposited on a wave-cut platform.
Longshore Drift
Longshore drift is the movement of material along the shore by wave action.
Longshore drift happens when waves moves towards the coast at an angle. The swash (waves moving up the beach) carries material up and along the beach. The backwash carries material back down the beach at right angles. This is the result of gravity. This process slowly moves material along the beach.
Longshore drift provides a link between erosion and deposition. Material in one place is eroded, transported then deposited elsewhere.
Transportation
Although longshore drift is the main process of transportation the material moves in four different ways. These are:
Traction - large material is rolled along the sea floor.
Saltation - beach material is bounced along the sea floor.
Suspension - beach material is suspended and carried by the waves. .
Solution - material is disolved and carried by the water.
Other Features Formed By Deposition
Longshore drift moves material along a coastline. Where there is an obstruction or the power of the waves is reduced the material is deposited. Where rivers or estuaries meet the sea deposition often occurs. The sediment which is deposited usually builds up over the years to form a long ridge of material (usually sand or shingle). Such a ridge is called a spit. Spurn Head on the Holderness Coast is an example of this feature.
