Geography - The Coastal Zone

A set of cards for the Coastal Zone topic.

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  • Created by: FiFi
  • Created on: 22-04-11 10:41

Erosion Processes (CHASA)

Corrasion

  • Fragments of rock are picked up and hurled at the cliff by the sea.
  • The rocks scrape and gouge the cliff face.

Hydraulic Power

  • The power of the waves as they smash into the cliff face.
  • Trapped air is blasted into cracks causing the rock to break apart.

Attrition

  • Rock fragments carried in the sea knock against each other in the water,
  • The rocks become smaller and rounder.
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Erosion Processes (CHASA)

Solution

  • Some rocks can be dissolved by seawater.
  • The main rocks that do this are, limestone and chalk.
  • Limestone and chalk form many cliffs in the UK

Abrasion

  • The sandpaper effect.
  • Pebbles grind over a rocky platform.
  • Creating a smooth platform.
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Types of Weathering

Mechanical

  • This is where rocks are broken down without any change in the chemical nature of the rock.
  • The rocks are 'torn' apart by physical force, rather than by a chemical breakdown.
  • E.g. Energy form the earth's crust or freezing.

Biological

  • This is caused by living organisms.
  • E.g. Digging animals, microscopic plants, algae and Fungi.

Chemical

  • Takes place in almost all rock types.
  • Reactions break the bond holding rocks together and they fall apart.
  • Common where there is water
  • E.g. Oxidation, Carbonation or Hydrolysis
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Longshore Drift

  • The process of moving sediment down the beach
  • Prevailing winds mean the Swash carries sediment up the beach.
  • The Backwash carries the sediment back down the beach.
  • The waves are at an angle when they approach the beach.
  • It doesn't happen at all beaches because most waves come straight on.

(http://images-mediawiki-sites.thefullwiki.org/05/2/3/7/81716573416364184.gif)

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Hard and Soft Engineering

Hard

  • Artifical structures are used to control natural processes.
  • E.g. Sea Walls, Rock Armour or Groynes

Soft

  • A sustainable approach, which uses natural techniques, is used to control natural processes.
  • E.g. Beach nourishment, Dune regeneration, Mananged Retreat
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Impacts of Coastal Erosion

Cliff Collapse

  • A wave-cut notch occurs because of erosion then the cliff becomes unstable and collapses.

Impacts Of Coastal Erosion

  • Loss of houses
  • Loss of habitat for wildlife
  • Job losses
  • No house insurance
  • Injuries
  • Loss of tourism and money
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Salt Marsh Case Study - Keyhaven Marshes, South Co

Threats

  • The beach is retreating up to 6m per year.
  • The marsh is eroding which exposes the beach.
  • More tourism is causing pollution and damage to the Marshes.
  • Sea levels are rising and the low sea wall is under threat.

The Wildlife

  • The Ringed Plover feeds and nests on the salt marsh.
  • The Wold Spider clings to Cordgrass waiting for food.
  • The Sea Lavender attracts Wildlife and is pretty.

Management Plans

  • Rock Armour and beach Nourishment was introduced in 1996, and the spit has not been breached.
  • The marsh is now a SSSI so access is limited and the area is being watched.
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Formation of a Spit

  • Longshore Drift transports sediment down the coast.
  • When the coast changes direction (e.g. a headland) the sediment starts to build out to sea.
  • This continues until a sand barrier has bulit away from the coast.
  • If the prevailing wind changes direction then the spit can get a curved end.
  • A spit can turn into a bar.

(http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBytes%20GCSE%20Blog%20Resources/Images/Coasts/Beaches.jpg)

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Headlands and Bays

Headland - resistant sections sticking out from the coast. They are more vulnerable to powerful waves creating a wave-cut notch.

(http://i3.squidoocdn.com/resize/squidoo_images/250/draft_lens13463401module120057521photo_1284660777headland_formation.JPG)

Bays - weaker sections erode quicker. These are sheltered, and less powerful waves build a sandy beach.

Bay and headland in New Zealand (http://www.bbc.co.uk/schools/gcsebitesize/geography/images/coast_011.jpg)

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Caves, Arches, Stacks and Stumps

Caves - a soft part of a rock cracks and gets eroded by Hydraulic power. This carried on until the cave gets bigger, but doesn't go all the wat through.

Arches - an arch is where a cave has been eroded all the way through on a headland.

Stacks - the top of an arch has fallen down after years of erosion as it can't be supported any more.

Stumps - a stack has been eroded so much that in shrinks in size becoming a Stump.

(http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBlogBytes%20Blog%20Resources/Year%2010%20Resources/Images/Erosion_Headland.png)

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Comments

Summita

Thanks Fiona! This was very useful to me.

Samuel

thanks very helpful

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