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Coastal Processes (Methods of erosion (Factors that affect the rate of…
Coastal Processes
Methods of erosion
Hydraulic Action
Force of waves pounding on coast. Most effective on lines of weaknesses in rock. Cracks are widened and loose material is broken away. Most effective during storms. Can create pressure of up to 25 tonnes per meter squared.
Air Compression
When air is trapped in bedding planes, it is compressed. Sudden compression is followed by sudden expansion of air as waves retreat. Creates an explosive effect,weakens the rock and therefore making it more open to other forms of erosion.
Abrasion
Rock particles carried by waves are thrown against the base of the cliff, breaking off particles and undercutting the cliff. Most effective method, especially during storms when waves are armed with a large load.
Attrition
Eroded rock particles collide and are themselves worn down, becoming smaller and more-rounded. Smaller particles of shingle and sand can then be removed by currents and tides.
Solution
Leads to coastal erosion. Rocks that contain minerals that can be dissolved by salts in seawater. (Limestone and chalk)
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Wave Refraction: process by which waves bend and change direction as they approach the shore.
Bay-head beaches: wave refraction allows erosion on headlands and deposition on bays, forming bay-head beaches, ie. Mizen Head
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Wave Refraction: process by which waves bend and change direction as they approach the shore.
Bay-head beaches: wave refraction allows erosion on headlands and deposition on bays, forming bay-head beaches, ie. Mizen Head
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Waves
Constructive:
Depositional
Low
long wavelength
spill gently onto the shore
Low frequency
Caused from distant storms
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Refraction
This is the process that the wave changes speed and direction as it approaches the shore! :)
Friction causes the wave to slow down
Waves approaching headland will use its energy for erosion. As a wave enters a bay the waves spread out where deposition can occur!
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Swash -Material pushed up by a beach Backwash-Material brought down the beach through water Storm beaches- steep ridges of large stones shingle and gravel,thrown up by strong storm Back-shore-the upper part of the beach Foreshore- lower part of the beach Land forms of deposition-Beaches,build up of sand boulders pebbles,sand,mid,shingle or even small shells all formed by weathering and erosion Long-shore Drift -Waves approach the beach at an angle and then move the sediment along the beach as it retracts and repeats.
Berms-Ridges of coarse material built up on shingle beaches by constructive waves in summer. They run parallel to the breaking waves and are found below the storm beach.
Ridges- Sand develop on the seaward edge of the foreshore and run parallel to the coastline.They develop as a result of constructive wave action near the point where the wave breaks. When a series of ridges develop, they are separated by depressions called runnels
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