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Coasts - Coggle Diagram
Coasts
Erosional Landforms
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concordant coastlines - has the same type of rock along its length, tend to have fewer bays and headlands
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definitions
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storm beach - caused by high tidal waves and the material and rocks build up at the back of the beach during storms
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coastal management - if sea defences are built, the coastal recession rate will be much slower
types of erosion
ABRASION: the process of waves hurling material it's carrying against the cliff faces which makes the cliff face weaker
ATTRITION: occurs when material being carried by waves rub against each other forming smaller rounded beach material
HYDRAULIC ACTION: when the waves crash at the base of the cliffs forcing water and air into the cracks, growing and expanding them
CORROSION: when ocean water develops a slight acidity, when waves reach limestone and chalk coasts small parts of the cliff will dissolve in the water
longshore drift
- swash at an angle, backwash vertical at 90 degrees
- zig-zag pattern as the process continues
- prevailing wind at an angle
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particle transportation
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SOLUTION: the process where some rock minerals slowly dissolve in water, which is slightly acidic
waves
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definitions
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fetch - the distance of open water a wave has travelled, driven by wind
types of weathering
BIOLOGICAL WEATHERING - PLANT ROOTS: plant roots put pressure on rocks causing them to disintegrate. burrowing animals excavate material leading to cliff or rock faces becoming unstable
CHEMICAL WEATHERING - ACID RAIN: water vapour absorbs pollutants and substances creating acid rain which falls on cliffs dissolving them
PHYSICAL WEATHERING - FREEZE-THAW: occurs when water gets into cracks in rocks, freezes and expands. the repeated freeze-thaw action puts pressure on the rocks until they eventually crack and break the rock. usually occurs in areas where the temperature flucuates around freezing point in day and night
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Depositional Landforms
Spits & Bars
- deposition - sediment builds up (accumulates)
- spit - sandy ridge projecting out to sea
- longshore drift has momentum and continues out into open water
- the spit will curve - secondary prevailing wind
- sudden change in the direction of the coastline
- salt marshes form stagnant - low energy
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sliding - occurs when the material is moved along the surface of the cliffs. weathering loosens large amounts of surface rock which will slide over more secure underlying materials
mass movement - is the large scale removal of material from cliff faces as a result of gravity and facilitated by high water content. this is a slow process containing surface material
slumping - occurs most commonly after prolonged periods of rainfall. rain is absorbed by permeable rocks on the cliff. as the rock gets wetter, friction between the rock and the cliff is reduced, causing it to slump, slide & collapse
rock falls - happen suddenly when pieces of large rock fall form a cliff. this often occurs when the base of the cliff is undercut by waves, leaving overlying rock unsupported
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