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  • Created on: 15-05-14 19:04
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Geography: Coasts Revision
Key words
Weathering: the decomposition and disintegration of rock material in situ (its original place)
Erosion: the wearing away and removal of material by a moving force
Mass movement: Removal of cliff-face material under influence of gravity (e.g. Rock falls/slides/
Wave: ridge of water formed by circular movement of water near surface of the sea
Concordant coastline: layers of hard and soft rock parallel to coastline
Deposition: accumulation of material along shoreline. Waves lay down this material when they
reach a sheltered area
Fetch: length of time/distance over which wind has been blowing
Swash: forward movement of water up the beach until all energy lost- from wave breaking
Backwash: movement of water down beach due to gravity
Wavelength: distance between two successive crests/troughs
Wave height: distance between a crest (top of wave) and trough (bottom of wave)
Sub-aerial processes- Weat hering
1. Freeze-thaw- mostly in highland areas
a. Water enters cracks
b. Water expands as freezes, enlarging crack
c. Over time cracks enlarge so much that bits of rock fall off
d. Rocks build up to form screes on slopes
2. Exfoliation- mostly in deserts
a. Outer layers heated by sun and expand
b. At night rock cools + contracts
c. Over time, a layer will `peel' off
1. Salt crystallisation
a. Salt water is high in salt
b. Sea water at coast bombards cliff face
c. Water evaporates easily, leaving salt crystals
d. Salt crystals invade rock, causing breakdown
2. Oxidation- affects iron-rich rock + visible by rust colour
a. Result of exposure to water
b. Causes chemical breakdown of rock
1. Mechanical: roots of plants (esp. Trees) growing in cracks in rocks, eventually split rocks apart
2. Chemical: Release of organic acids from vegetation breaks rocks down
Land forms created by coas tal erosion
- Discordant coastlines (hard and soft rock at right angles to sea)
- Weak rocks eroded by abrasion bay beach
- Headlands formed from resistant hard rock cliffs

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Depositional landforms
- Formed when material builds up faster than waves can move them away. Waves are
constructive (stronger swash than backwash). Destructive waves erode material so provide
sediment for deposition
- Spit- formed by material transported by LSD to the end of the beach in areas where coastline
changes direction (sediment low energy environment deposited as can't be transported).
If there's a river, spit causes it to deposit sediment on landward side of spit, causing salt
marshes to form.…read more

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Hard rock Soft rock
Shape of cliffs High, steep Lower, less steep
Cliff face Rugged bare rock Smoother rock, evidence of slumping
Foot of cliff Boulders, rocks Sand, mud, few rocks
- Must be adapted to saline conditions
- Preserve and protect coastal landforms (see: Coral reefs, mangroves)
Sea-level change
- Eustatic change: global sea-level change from change in ocean volume due to (inter)glacial
- Tectonic/isostatic change: relative rise or fall in land due to tectonic/local glacial activity
- Isostatic rebound: rise in…read more

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Pollution (e.g.…read more

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Photo Type of defence Pros and cons
Sea wall- absorb and reflect Pros: protect base of cliff/buildings/land,
power of waves can prevent coastal flooding
Cons: Expensive to build and maintain,
erode over time, curved walls reflect
energy waves remain powerful
Groyne- wooden/concrete/ Pros: prevent movement of material, allow
stone barrier at right angle to build up of beach (natural sea defence,
beach, interrupting water flow tourist attraction)
and transportation of material Cons: Unattractive, expensive to build/
by LSD maintain, many needed
Rock armour- boulders Pros:…read more

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Photo Type of defence Pros and cons
Cliff regrading and re-vegetation- Pros: work with nature
cliffs cut back gentle slope no sustainable, prevent cliff collapse,
slumping. Drainage pipes installed vegetation = new habitats for wildlife
remove excess water and prevent slip Cons: expensive/complex
planes.…read more

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Less sediment deeper Humber estuary inland more susceptible to flooding
- Defences aren't long term due to sea-level rising
Stakeholders' views
- Stakeholders: local council, taxpayers, residents, business owners, conservationists/scientists
- East Yorkshire council: want to limit impact (cost-benefit analysis), balance of everyone's
requirements (so sediment Humber must continue to stop inland flooding)
- East Yorkshire council tax payers: Balance between sea defence and land loss wanted (tax pays
for both)
- Hornsea cliff top caravan site owner: in favour of any engineering strategy to…read more

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How it's being managed
- Environmental: threatened vegetation (e.g.…read more


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