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.
What are the 2 landforms of coastal erosion?
Cliffs and wave cut platforms
Cliff profile features
What are the 3 factors affecting the development of cliffs and wave cut platforms?
Rock type
Wave energy
Coastal morphology
Explain how wave cut platforms form.
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.
Which type of erosion is the most significant in forming wave cut notches?
Abrasion
What angle are wave cut platforms at?
Less than 5 degrees
Why do wave cut platforms not grow bigger than 500m?
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
How can wave-cut platforms become rough and jagged?
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.
What features may form on wave cut platforms that remain in the tidal zone?
Rock pools and fissures
Give an example of a wave cut platform in the UK.
Flamborough Head, North Yorkshire
Give an example of a wave cut platform outside of the UK.
Muckross Head, Donegal, Ireland
How long can wave-cut platforms take to form?
100s - 1000s of years
Name 6 cliff profile features.
Geos Caves Blowholes Arches Stacks Stumps
How do geos form?
The sea will cut inland along a joint in a cliff, widening the crack to form a geo
What is a geo?
A narrow, steep-sided inlet in a cliff
How do caves form?
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.
Where do caves often form and why?
Headlands as erosion is strongest here
How do blowholes form?
Oncoming waves applied to the rear of a cave can enlarge joints in the cave roof and weaken the overlying rocks until they collapse.
How do arches form?
Refraction around headlands causes caves on either side of the headland to extend backwards until they erode through the headland.
How do stacks form?
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.
What are stacks?
Isolated portions of rock standing above a wave cut platform.
How do stumps form?
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.
What will happen to a stump over time?
It will slowly be eroded to the level of the wave-cut platform.
Give an example of cliff profile features in the UK.
Old Harry’s Rocks, Dorset
Give an example of cliff profile features outside the UK.
The Twelve Apostles, Victoria, Australia
What factors affect the development of cliff profile features?
Rock type
Nature of waves
How long does the entire process of forming cliff profile features take?
100s - 1000s of years