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Coastal Landforms (Beaches (The material found on a beach varies in size…
Coastal Landforms
Beaches
Beaches are made up of eroded material that has been transported from elsewhere and deposited by the sea.
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Most waves break near the shoreline, so sediment near the water is more effectively broken down by attrition.
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Caves, arches, stacks and stumps
Weathering and erosion can create caves, arches, stacks and stumps along a headland.
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Caves occur when waves force their way into cracks in the cliff face. The water contains sediment that grind away at the rock until the cracks become a cave. Mainly caused by Hydraulic action .
If the cave is formed in a headland, it may eventually break through to the other side forming an arch.
The arch will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.
The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump.
One of the best examples in Britain is Old Harry Rocks, a stack found off a headland in the Isle of Purbeck.
Spits
A spit is an extended stretch of beach material that projects out to sea and is joined to the mainland at one end.
Spits are formed where the prevailing wind blows at an angle to the coastline, resulting in longshore drift.
An example of a spit is Spurn Head, found along the Holderness coast
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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 area where silt is deposited and mud flats or salt marshes form.
Cliffs
One of the most common features of a coastline is a cliff. Cliffs are shaped through a combination of erosion and weathering - the breakdown of rocks caused by weather conditions.
Soft rock, eg sand and clay, erodes easily to create gently sloping cliffs. Hard rock, eg chalk, is more resistant and erodes slowly to create steep cliffs.
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Tombolos
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An example of a tombolo is Chesil Beach, which connects the Isle of Portland to the mainland of the Dorset coast.
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Headlands and Bays
Headlands are formed when the sea attacks a section of coast with alternating bands of hard and soft rock.
The bands of soft rock erode more quickly than those of more resistant rock This leaves a section of land jutting out into the sea called a headland. The areas where the soft rock has eroded away, next to the headland, are called bays.
Coastlines where there are alternating bands of hard rock and soft rock are called discordant coastlines. A concordant coastline has the same type of rock along its length.
