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Depositional landforms - Coggle Diagram
Depositional landforms
Beaches
What is this feature?
Beaches are deposits of sand and pebbles at the coast. Sandy beaches are mainly found in sheltered bays. Not all beaches are made of sand. Much of the South Coast of England has pebble beaches.
How is it formed?
The Waves entering the bay are constructive waves, they have a strong swash and build up the beach. These high energy environments wash away the finer sand and leave behind the larger pebbles
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Beach at Durdle Door. Located on the Jurassic Coast in Dorset. It is a famous shingle and pebble beach. It features a striking 200 foot tall natural limestone arch
Tombola
What is this feature?
A tombolo is a feature of deposition that takes the form of a narrow landform made of sand that connects an offshore island to the mainland.
How is it formed?
Tombolos are formed when a spit is formed between the coastline and an island. Material is pushed onto the beach at an angle when the swash brings it onto the beach at a 45% angle. If the beach then changes direction, such as at a river estuary, the sediment is deposited and forms a spit. If this forms in the direction of an island, it forms a Tombolo
specific example
St Ninian's Isle tombolo it measures about 500m long and 70m wide and Locally referred to by the Old Norse term ayre
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Waves bend around an offshore island, creating a calm, protected zone of water directly behind it.
Lacking the power to push sediment away, the calm water drops sand and stones. Over centuries, this debris piles up until it creates a walkway.
Many tombolos are tidal pathways. This means they emerge beautifully at low tide but disappear completely underwater during high tide.
The UK is home to St Ninian’s Isle in Shetland (the largest active sand tombolo in Britain) and the famous Chesil Beach in Dorset.
Dune
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A sand dune is a mound, hill or ridge formed from sand, usually deposited by the wind.
At beaches, they normally have grass on them..
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Sand dunes are formed when onshore waves deposit sand piled up around an obstacle such as rocks or driftwood, forming mounds and ridges.
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-Usually occur on a wide, flat beach
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Merthyr Mawr Nature Reserve, Wales
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Saltburn Beach, Yorkshire
bar
What is this feature?
A bar, which is a ridge of sand, sediment, gravel or shingle which has been deposited by water which runs between two headlands and it grows completely across the mouth of the bay, running parallel to the coast.
How is it formed?
It is formed when the coast has a gap of water in it , longshore drift moves the sediment along the shore, this will eventually meet with the gap and block off the water, this connects the beaches together forming a lagoon behind it.
Place specific example:
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In between St Agnes and Gugh, Isles of Scilly
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A sandbar is an exposed or submerged ridge of sand, silt or gravel built offshore or across a bay.
An offshore bar forms further out to sea. Waves approaching a gently sloping coast deposit sediment due to friction with the seabed
salt marsh
What is this feature?
A salt marsh is a Tidal coastal wetland regularly flooded by salt water and dominated by saltwater tolerant plants that trap and bind sediment to the bottom of the mash bed .
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-Buffers wave energy leading to shoreline protection, less coastal erosion and storm protection.
-Works as a natural filter as it gets rid of extra nutrients in water before it reaches the coastal waters.
How is it formed?
The salt marshes at Dawlish Warren formed because a long sand spit blocks rough ocean waves, creating a calm area behind it. In the sheltered water behind the spit, deposits of mud have built up. An extensive saltmarsh had formed as vegetation has started to grow in the emerging muddy islands.
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spits.
What is this feature?
A spit is a long, narrow ridge of sand or shingle that is attached to the mainland at one and and extends out to the sea or across an estuary. It is made of transported sand or pebbles and materials are often smaller at the end due to attrition.
Key facts?
A spit is a narrow, long ridge of sand or shingle that is joined to the mainland at one end and extends out into the sea or across an estuary
How is it formed?
A spit forms when longshore drift moves sediment along a coast until the shoreline changes direction. Waves lose energy and deposit sand and shingle out into the open water, building a ridge. Secondary winds bend the tip into a recurved hook, and a salt marsh forms in the calm water behind it.
Place specific example
Dawlish warren is a rare, double sand spit located at the mouth of the Exe estuary in devon. It extended roughly 2.5 kms northeast from langstone rock toward exmouth, it acts as a natural barrier that keeps the estuary safe from flooding and severe wave action