Coasts: Coastal landscape development - Landforms and Landscapes of Coastal Erosion Flashcards

Origin and development of landforms and landscapes of coastal erosion: - cliffs and wave cut platforms - cliff profile features (caves, arches, stacks) Factors and processes in their development.

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1
Q

What are the 2 landforms of coastal erosion?

A

Cliffs and wave cut platforms

Cliff profile features

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2
Q

What are the 3 factors affecting the development of cliffs and wave cut platforms?

A

Rock type
Wave energy
Coastal morphology

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3
Q

Explain how wave cut platforms form.

A

When destructive waves break at the foot of a cliff their energy is concentrated onto a small area of the rock face between HWM and LWM.
Erosion undercuts the cliff forming a wave cut notch.
The overhanging cliff is subject to weathering and eventually collapses.
After successive collapses the cliff line will begin to retreat, forming a gently sloping wave cut platform at the base of the cliff.

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4
Q

Which type of erosion is the most significant in forming wave cut notches?

A

Abrasion

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5
Q

What angle are wave cut platforms at?

A

Less than 5 degrees

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6
Q

Why do wave cut platforms not grow bigger than 500m?

A

As the platform grows the waves break further out to sea and their energy is dissipated before reaching the cliffs - forming a negative feedback loop

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7
Q

How can wave-cut platforms become rough and jagged?

A

If the platform remains in the tidal zone it will be continually exposed to cycles of marine and sub-aerial processes, exploiting weaknesses in the rock surface.

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8
Q

What features may form on wave cut platforms that remain in the tidal zone?

A

Rock pools and fissures

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9
Q

Give an example of a wave cut platform in the UK.

A

Flamborough Head, North Yorkshire

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10
Q

Give an example of a wave cut platform outside of the UK.

A

Muckross Head, Donegal, Ireland

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11
Q

How long can wave-cut platforms take to form?

A

100s - 1000s of years

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12
Q

Name 6 cliff profile features.

A
Geos
Caves
Blowholes
Arches
Stacks
Stumps
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13
Q

How do geos form?

A

The sea will cut inland along a joint in a cliff, widening the crack to form a geo

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14
Q

What is a geo?

A

A narrow, steep-sided inlet in a cliff

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15
Q

How do caves form?

A

Hydraulic action exploits cracks in a cliffs, opening them up. If the cliff is under cut, the crack will grow into a cave by hydraulic action and abrasion.

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16
Q

Where do caves often form and why?

A

Headlands as erosion is strongest here

17
Q

How do blowholes form?

A

Oncoming waves applied to the rear of a cave can enlarge joints in the cave roof and weaken the overlying rocks until they collapse.

18
Q

How do arches form?

A

Refraction around headlands causes caves on either side of the headland to extend backwards until they erode through the headland.

19
Q

How do stacks form?

A

As the cliff recedes and a wave cut platform develops, the unsupported roof of the arch will eventually collapse due to marine erosion from below and sub-aerial processes weakening the arch.

20
Q

What are stacks?

A

Isolated portions of rock standing above a wave cut platform.

21
Q

How do stumps form?

A

Stack bases are in the intertidal zone so are subject to erosion, forming a wave cut notch. Over time the sea will exploit the wave cut notch at the base of a stack eventually leading to its collapse.

22
Q

What will happen to a stump over time?

A

It will slowly be eroded to the level of the wave-cut platform.

23
Q

Give an example of cliff profile features in the UK.

A

Old Harry’s Rocks, Dorset

24
Q

Give an example of cliff profile features outside the UK.

A

The Twelve Apostles, Victoria, Australia

25
Q

What factors affect the development of cliff profile features?

A

Rock type

Nature of waves

26
Q

How long does the entire process of forming cliff profile features take?

A

100s - 1000s of years