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Depositional Features - Coggle Diagram
Depositional Features
Spits
What are they?
Extended stretch of beach material that projects out to sea and is joined to the mainland at one end.
How are they formed?
The prevailing wind pushes constructive waves up the beach at an angle as the swash. The waves then travel at a ninety degree angle back down the beach due to gravity, resulting in longshore drift.
Extra
Spits don't have much variety but the variety that is there is; some that bend shoreward, looped spits.
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Saltmarshes
What are they?
Coastal wetlands, Soil made of peat and deep mud - waterlogged and spongy, Flooded and drained by salt water that is bought in by tide
How are they formed?
Sediment (usually mud or sand)that had flowed down the river or estuary collects behind a spit (formed as a result of longshore drift).
Extra
Salt Marshes can absorb up to 1.5 million gallons of flood water and by filtering runoff and nutrients it helps maintain water quality of the area around it.
Estimated that salt marshes can save about £650,000 due to salt marshes being very effective at preventing flooding and storm surges.
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Bars
What are they?
Stretch of shingle or sand stretching from one point of a coastline to the next - typically headland to headland.
How are they formed?
Sandbars are formed by deposition of sediment through longshore drift - or sometimes at the mouth of a river; where there is a gap (such as a bay) in the coastline.
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Tombolos
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How are they formed?
Waves refract either side, creating the tombolo in the centre of a sheltered area.
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Extra
The tombolo to burgh island reaches out from Bigbury Beach and is accessible on foot during low tide. A sea tractor is used to cross the distance between Burgh Island and Bigbury beach when the tide is high.
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Sand dunes
What are they?
A mound of sand this is formed by the wind, usually along the beach or in a desert
How are they formed?
They form by gusts of wind that carry sand up the beach, (usually a large, thick beach is optimal so wind can pick up even more sand and dunes are bigger), which is then caught by a wall such as grass this wall will eventually contain enough sand to form a mound the mound piles up sand on the windward side until it forms a dune.
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Extra
Sand dunes occur widely around the coastline of the UK, with particularly large areas in the Hebrides and fewer along the south coast.
Some time after the formation of the sand dune sand piles up too much on one side of the dune until it collapses and the process starts again.
Beaches
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Extra
Beaches are covered in sand, a product of attrition on rocks
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