Coastal Landforms

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Cliffs and Wave-Cut Platforms

Description

A rocky platform that extends from the cliff base to the sea

It has a 4-5 degree slope angle 

Covered by the sea during high tide/exposed at low tide 


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Cliffs and Wave-Cut Platform cont.

Explanation 

1. Destructive waves attack lines of weakness between high and low tide 

2. Erosion of the joint or bedding plane through process such as abrasion (rocks knocking against cliff breaking pieces off) and hydraulic action (air compressed in cracks, pressure exerted by compressed air and rock breaks off). This creates a wave cut notch

3. Continued erosion of the wave cut notch eventually forms an overhang 

4. Overhang eventually collapses as unable to support itself

5. The cliff retreats as a result of this. The debris is removed by the wave forming a platform 

6.The process repeats, extending the platform which eventually protects the cliff from erosion 


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Caves, Arches, Stacks and Stumps

Description 

A headland that extends out to the sea has lines of weakness which allows for coastal landforms to be formed.

The cave and arch are part of the headland.

The stacks and stumps show former position of the head land.

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Caves, Arches, Stacks and Stumps cont.

Explanation

1.Destructive waves attack lines of weakness between high and low tide 

2. Erosion of the joint or bedding plane through process such as abrasion (rocks knocking against cliff breaking pieces off) and hydraulic action (air compressed in cracks, pressure exerted by compressed air and rock breaks off). Widen the joint in the cave

3. Continued erosion of the cave eventually causes it to erode through the headland forming an arch

4. The arch is subject to erosion. which makes it more pronounced on the top which is attacked by weathering such as freeze-thaw (were repeated expansion and contraction of a crack due to water leads to the rock breaking) and sub-areail causes the top of the arch to break 

5. The arch eventually collapses, causing the headland to retreat and a stack to be formed


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Caves, Arches, Stacks and Stumps cont. 2

Explanation cont.

6. A stack shows the former headland. It is attacked by erosion and wave cut notches are formed

7.Eventually the stack becomes unstable due to erosion and collapses forming a stump

8.The process begins again

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Geo

Description

An extended inlet along the bedding up the cliff profile which is narrow and steep sided 

Explanation

1.Destructive waves attack lines of weakness between high and low tide 

2. Erosion of the joint or bedding plane continues upwards as well as eroding the headland further back

3. A geo is formed when erosion and weathering along the plane continues far enough up to from and inlet

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Blowhole

Description

A cave that has extended upwards and collapsed opening up to the sky 

Explanation 

1.Destructive waves attack lines of weakness between high and low tide 

2. Erosion of the joint or bedding plane through process such as abrasion (rocks knocking against cliff breaking pieces off) and hydraulic action (air compressed in cracks, pressure exerted by compressed air and rock breaks off). This creates a wave cut notch and eventually a cave

3. The cave is eroded continually to widen and deepen. Depending on rock type the cave erodes upwards

4.At Flamborough Head the cliff top is boulder clay which is subject to mass movement and weathering making it unstable 

5. Material beneath the cliff surface is being eroded making it weaker that it eventually collapses forming a blow hole 


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Headlands and Bays

Explanation

1. Headlands and bays are formed along a discordant coastline, with alternative bands of hard and soft rock at right angles along the coastline 

2. Headlands are made up of hard rock and bays are made up of soft rock which is easier to erode 

3. Destructive waves attack a line of weakness which is the soft rock through abrasion (rocks knocking against cliff breaking pieces off) and hydraulic action (air compressed in cracks, pressure exerted by compressed air and rock breaks off)

4. Continuous of the erosion of soft rock leads to the formation of a bay and a headland of more resistant rock that extends into the sea 

5.The headland eventually becomes the focus of the waves power due to wave refraction leaving low energy waves to form to carry material to the bay to form a beach 

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Beaches

Explanation

1. Beaches are formed by constructive waves which deposit sediment 

2. Shingle beaches are steep and narrow where sand beaches are wider and flatter 

Beaches have:

Berms- which are ridges of sand and pebbles (1-2meters high) found at high tide 

Runnels - are grooves in the sand running parallel to the shore 

Cusps - are cresent shaped indentations 

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Spits and Bars

Explanation

Tend to form when the coast suddenly changes direction eg. river mouth 

1.Long shore drift deposits material across the river mouth leaving sand and shingle sticking out into the sea 

2.Directional changes in the dominant wind can lead to the spit curving 

3.Over time the wind changes leading to many curves off the spit 

4.Salt marshes and mudflats are formed behind the spit as they are sheltered from waves 

Bars: When two spits join together 

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Sand Dunes

Explanation

1.Sand is deposited by long shore drift and is moved up the beach by wind

2. Sand is trapped by driftwood and vegetation. This eventually stabilizes the sand and it begins to accumulate 

Conditions needed:

  • wide beach 
  • wide range between high and low tide 
  • strong on shore winds
  • plentiful supply of sand 
  • gentle beach profile
  • vegetation 
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Salt Marshes

Salt marshes form in areas of sheltered water

Explanation

1.Silt and mud are deposited by a river or the tide 

2. Mudflats are colonised by vegetation that can survive in high salt levels and be submerged by the tide

3.The plants trap more silt and create marsh land 

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