Coastal Landforms

All of the coastal Features you need to know for AQA Geography AS level!

Topics Covered:

Erosional:
Cliffs & Wave cut platforms
Headlands & Bays
Geos, Caves, Blowholes, Arches, Stacks & stumps

Deposition:
Beaches
Spits & Bars
Sand Dunes
Salt Marshes

Sea Level Change
Submergent Features
Emergent Features

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  • Created by: Alex
  • Created on: 09-05-11 22:07

Erosional

Cliffs & Wave Cut Platforms:
At high tide  they break at the foot of a cliff and all their erosive capabilities  are concentrated on one small area of rock. This combined with hdraulic pressure & abrasion eventually leads to the cliff being undercut forming a feature know as a wave cut notch

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Wave Cut Platform

(http://i494.photobucket.com/albums/rr301/aliisbest/wcp1234.jpg)

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Erosional - Headlands & Bays

Headlands and bays form from where there are bands of alternationg hard and soft (resistand & less resistant) rocks.

Less Resistant Rock experience most erosion and is erodedquickly forming a bay

The more resistant rocks is eroded less and sticks out as a headland

Once formed the headland are more vunerable to the power of refraction, which means the headland recieve the highest energy waves whilst the bays recieve gently waves allowigng them to form beaches, protecting the coastline.

If the bands of rock run parrell to the coast  continued erosion can break through toe more resistant rocl to attack the less resistant behind and a cove will form which will enlarge into a bay

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Erosional- Geos, Caves, Blowholes, Arches, Stacks

Allong the coastline on Cliffs or headlands these features will appear.
Along the cliff the sea will attack the weakest parts of the cliff such as cracks & joints.
Geo: A narrow steep sided inlet formed from the sea cutting inland widening the crack in the cliff

Caves, Blowholes, Arches, Stacks & stumps:
Weak areas in the rock of headlands(cracks & joints) are widened and eroded by a combination of marine processes  to form caves.
The cave will carry on eroding into the headland and will eventually meet another, creating a hole all the way through the headland which forms an Arch.
Ocassionally the roof of a cave is weakened along a major joint and as erosion continues upwards the roof collapses to form a narrow blow hole along the crack.
A wave cut platform will develop around the base of the arch.
With continued erosion of the bases the top of  the arch eventually colllapses leaving a Stack.
Continued erosion of the stack will cause it to collapse creating a stump

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Depositional-Beaches

Beaches are formed when constructive waves deposit Sediment upon the shore.
They are deposited between low spring tide and the highest point reached by storm waves.
They are mainly made up of sand and shingle with the largest particles towards the bac of the beach.
Shingle beaches are steep and narrow. they are made up of larger particles which pile up at steeper angles
Sand produces beaches of a gentle gradient (under 5 degrees). The beaches are very wide and flat and allow little percolation because of how the sand becomes compact when wet. - Most swash returns as backwash and little energy is lost to friction.

Ridges & runnels form at low water mark. They run parrallel to the shore and are grooves in the sand formed by the backwash into the sea. They're broken by channels allowing water to drain off the beach.

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Depositional- Beaches Continued

At the back of a shingle beach is a storm beach, a strong swash at high tide has created a ridge composes of large boulders thrown there by the spring high tides.

Below will be  a series of ridges marking the successively lower high tides and the cycle goes from spring to neap. These ridges are known as Berms and are foremed by constructive waves

Cusps are cresent-shaped indentations/depressions that form on the beaches made of sand and shingle when waves break directly onto the beach and swash & backwash are strong. It;s not known exactly how they form but develop on beaches of a large tidal range & where waves break parrellel to the shore.

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Deposition- Spits & Bars

A spit is a long, narrow piece of land that has one end joined to the land. It appears where the land changes direction suddenly, like across the mouth of an estuary.
They are made up of a mixture of sand and shingle, depending on the availability of material and the wave energy required to move it. Often they are made up of material eroded from cliffs and carried along by LSD.

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