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Depositional landforms - Coggle Diagram
Depositional landforms
Beaches
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Sand and shingle beaches
Sand
produces beaches with a gentle gradient, typically 5 degrees.
Small size means it stays compact when wet, allowing little percolation during backwash
This means little energy is lost to percolation and friction, which means sand is carried back down the beach during backwash, creating a gentle gradient.
Shingle beaches
Produces steep beaches because swash is stronger than backwash so there is a net movement of shingle onshore.
Shingle may make up the upper part of the beach where there is rapid percolation due to larger air spaces, meaning little backwash occurs leading to shingle being deposited at the top of the beach.
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Other features
Storm ridge/beach: storm waves hurl pebbles and cobble at the back of the beach much higher than the usual high tide mark, creating a storm ridge.
Ripples: further down in the beach, caused by the orbital movement of waves.
Cusps: small, semi circular depressions, caused by waves reaching the same point.
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Dynamic beaches
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For example: High energy, destructive waves would remove sediment offshore and create flatter profiles. This creates flatter profiles, resulting in shallow water, more friction and a reduction in wave energy.
Spits
What are they?
Long, narrow beaches of sand or shingle that are attached to land at one end and extend across a bay, estuary or coastal indentation.
How are they formed?
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The end of the spit often becomes curved due to wave refraction, or a secondary wind.
Over time as the spit develops, the numbers of curves and hooks may develop.
Other facts
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In the sheltered area behind the spit, deposition will occur as wave energy is reduced, eventually forming a salt marsh.
onshore bars
How are they formed?
They are formed by a spit developing across an indentation, like a cove or bay, to the point it reaches land at the other end.
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Salt marshes
How are they formed?
Salt marshes are low energy environments such as estuaries, and can be found on the landward side of spits.
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The higher the marsh, the shorter the amount of time of daily submergence.
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