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Coastal proceses can be split into two different categories:
  • Land procceses influencing our coastlines
  • Marine coastline influencing our coastlines

Video showing the processes of erosion - http://www.bbc.co.uk/learningzone/clips/weathering-erosion-and-coastal-features/4022.html

Excellent animation showing coastal processes and defences - http://www.as.uky.edu/academics/departments_programs/EarthEnvironmentalSciences/EarthEnvironmentalSciences/Educational%20Materials/Documents/elearning/module14swf.swf

Weathering

The processes of weathering affects rocks exposed at the coast. Freeze-thaw weathering in particularly effective if the rock is porous (contains holes) and permeable (allows water to pass through it). This can lead to dramatic rockfalls as shown below.

external image Fresh%20rock%20fall.JPG
Full explanation as to how freeze-thaw weathering works can be found at the following link:

http://onlinegeography.wikispaces.com/Ice+as+a+shaping+agent

Mass movement
Mass movement is the downhill movement of material inder the influence of gravity. In 1993 60m of cliff slid onto the beach near Scarborough in North Yorkshire, taking with it part of Holbeck Hall Hotel.
external image holbeckHall1.jpg

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Marine Processes
Coastal ersoion

Erosion – use the acronym CASH

Corrasion – (abrasion) is caused by large waves hurling beach material against the cliff
Attrition – is when waves cause rocks and boulders on the beach to bump into each other and to break up into small particles
Solution – (corrosion) is when salts and other acids in seawater slowly dissolve a cliff
Hydraulic pressure (power/action) – is the force of waves compressing air in cracks in a cliff
One final process of erosion is:

Abrasion: this is the 'sandpapering' effect of pebbles grinding over a rocky platform, often causing it to become smooth.

Coastal transportation

Processes of Transportation

  • Traction – rolling stones along the sea floor (needs the most energy)
  • Saltation – sand-sized particles bounce along the sea floor in a ‘leap frog’ movement
  • Suspension – silt and clay-sized particles are carried within the water flow·
  • Solution – some minerals dissolve in the water (this needs the least energy)

Longshore Drift
Video showing how Longshore Drift works - http://www.bbc.co.uk/learningzone/clips/landforms-created-by-longshore-drift-and-coastal-deposition/9965.html

  • Waves approach the beach in the same direction as the wind
  • When the wave breaks, swash carries material up the beach at the same angle as the wind
  • The backwash carries the material straight back down the beach under gravity·
  • This process slowly moves material along the coastline

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Remember when drawing:
  • To draw in a beach
  • An arrow showing the prevailing wind
  • An arrow showing the direction of longshore drift
  • To draw in the movement of the pebbles
  • To use the terms ‘swash’, ‘backwash’ and ‘gravity’ when describing the movement of the pebbles

Coastal deposition

Deposition occurs in areas where the flow of water slows down. The sediment can no longer be carried or rolled along an has to be deposited. Coastal depostion most commonly occurs in bays, wherew the energy if the waves is reduced on entering the bay. This explains the presence of beaches in bays and accounts for the lack of beaches at headlands, where the energy of the waves is uch greater.