Coastal Deposition Flashcards
What is Coastal Deposition?
Coastal 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 that the backwash and is associated with constructive waves.
When is Coastal Deposition likely to occur?
Deposition is likely to occur when:
Waves enter an area of shallow water
Waves enter a sheltered area e.g., a cove or bay
There is little wind
There is a good supply of material
What landforms can Coastal Deposition lead to?
Beaches and Spits.
What is a Spit?
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 in an example of this feature.
How is a Spit formed?
Formation of a spit
Longshore drift moves material along the coastline.
The coastline suddenly changes direction. Deposition continues into shallow, sheltered areas and material continues into to be deposited.
A spit is formed from this deposited material.
Over time, the spit grows and develops a hook if wind direction changes further out.
Waves cannot get past a spit, which creates a sheltered are where silt is deposited and mud flats or salt marshes form.
What is a Bar?
Bar – If the bay between two headlands is blocked off by a spit, then that spit is known as a bar. The body of water behind the bar is known as a lagoon. An example of a bar is Slapton Ley in Devon.
What is a Tombolo?
Tombolo – Sometimes a spit extends far enough out to sea to join a coastal island to the mainland. When it does so, the spit is known as a tombolo.
