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Saturday, January 21, 2012

COAST: Depositional Landforms

Coastal Deposition is when the sea drops or deposits material. This can include sand, sediment and shingle.

Beaches
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.



Spit
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.




MARSHES

Salt Marshes
A salt marsh is a coastal marsh that forms on mud flats. They usually form in very sheltered inlets and estuaries, or behind spits (places where fine sediment accumulates). Salt marshes form as vegetation builds up on these mud flats.



Sand Dunes
Sand dunes are created by strong winds and not by coastal erosion or deposition. As sand is blown up a beach is forms small hills. These are often rooted together by long-rooted grasses such as marram grass. Marram grass is usually planted to reduce the erosion of the otherwise unstable sand dunes.