Marine Erosion/Transportation/Deposition

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Coastal Erosion

Hydraulic Action (Wave Quarrying): Cracks in the rocks fill with air, wave hits rocks, compressing the air inside. Due to high pressure, the crack is forced apart. Erosion due to the force of water hitting the rocks.

Abrasion/Corrasion: Scouring of the seabed by sediment, or when sediment is thrown at the cliffs.

Attrition: Rocks and sediment in the sea become rounder, smoother and smaller when they bash into eachother.

Solution/Corrosion: Certain rock types dissolve in water eg. Chalk, clay and limestone.

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Rate of Erosion

Lithology: Type of rock and its characteristics have different resistance to erosion. Rocks that are well jointed erode quickly as the sea can penetrate along lines of weakness. Variation in rates is called differential erosion.

Sea depth: Steeply shleving sea beds at the coast creates higher and steeper waves, meaning the have more energy and therefore potential to erode.

Fetch: The further a wave has travelled, the more energy it has collected meaning it has higher eroding potential.

Coastal Configuration: Headlands attract wave energy through refraction.

Beach Presence: Beaches absorb wave energy and provide protection against erosion. Shingle beaches dissipate energy through friction and percolation.

Human Activity: People may remove protective materials from beaches leading to more erosion or can reduce it by building sea defences.

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Transportation/Longshore Drift

Saltation: Sediment is bounced along the sea bed.

Traction: Heavy sediment is rolled, doesn't break contact with sea bed.

Suspension: Sediment is carried in water.

Solution: Sediment is dissolved in water.

Longshore Drift: Transport of sediments at an angle along the shore line depending on the direction of the prevailing wind. The swash carries the sediment up the beach in the direction of the wind at an angle, and the backwash carries it back at 90 degrees (perpendicular).

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Occurs where there are low energy environments in sheltered areas eg. behind spits and bars.

Occurs when the coastline changes direction.

Occurs where obstacles prevent movement of sediment, eg. groynes.

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