SUMMARY

• longshore drift


  The movement of water and sediment down a beach caused by waves coming into shore at an angle. the uk moves material from west to east

  
• how are beaches formed


  when material is transported by longshore drift and deposited by constructive waves.
• where are sandy beaches found

  sheltered bays, they have shallow gradients
• where are pebble beaches formed


  areas where cliffs have been eroded by high energy waves, they have a steep gradient
• spit


  narrow ridge of shingle stretching out into coastline, forms due to longshore drift at a change of coastline. shingle gets deposited

  
• bar


  ridge of shingle that extends across a bay/rive mouth. behind it, fresh/saltwater forms a lagoon.
• settlement affecting the coastline

  20million people live near the coast. 29 villages lost due to coastal erosion
• tourism affecting the coastline

  13% jobs at Dawlish are tourism. coasts often managed for tourists (with groynes etc)
• infrastructure affecting the coastline

  roads/railways/shipping ports/oil refineries.

  esso sees 2000 ships dock every year
• construction affecting the coastline

  dredging the sea to construct ports can have adverse affects on wildlife. they can also adjust the sediment cells
• agriculture affecting the coastline

  farmland will be impacted due to sea level rise because of increased coastal erosion because it's low economic value and low priority in management
• bournemouth beach


  tourism, settlement and infrastructure

  
• holderness coastline


  agriculture, settlement

  
• rising sea level uk

  english channel expected to rise 15cm by 2030, caused by thermal expansion and melting ice sheets/glaciers
• what is a storm/storm surge

  large increase in sea level due to a storm. strong winds drive up the waves, whilst low pressure allows the sea level to rise up 3m above normal.
• hold the line


  maintain the existing coastline with defences
• managed realignment


  allow the shoreline to change naturally, but manage the process and the impacts
• advance the line


  build new defences on the seaward side
• sea wall


  -protects base of cliff. made of resistant concrete that deflects energy

  -expensive and ugly, restricts access

  
• groynes


  -maintain a wide beach and attract tourists

  -high maintenance cost, could impact other areas of coastline in sediment starvation
• beach replenishment


  -looks natural, attracts tourists, cheap

  -material easily eroded and needs constant replenishment

  
• slope stabilisation


  -prevents mass movement, safer for people using the beach

  -difficult to install, very expensive
• waves


  caused by friction that is generated when wind blows across the surface of the sea
• destructive waves


  strong winds, powerful waves, cause coastal erosion. tall, steep. backwash stronger than swash, so material is carried out to sea
• constructive waves


  light winds, cause deposition not erosion. stronger swash, so material is deposited on the beach
• attrition


  small rocks collide with eachother. break up, becoming smaller and rounder, until the rock becomes sand
• abrasion


  rocks thrown against the coastline. wears the coastline away over time
• hydraulic action


  large waves break against the cliff. water forced into the faults/cracks causing immense pressure. when it is released, it produces a force that makes the crack wider.
• solution


  chemicals in the sea react with the rock so it dissolves. occurs mainly with limestone.
• discordant coastline


  bands of different rock strengths run 90degrees to coastline. in dorset, clay, chalk and limestone form a discordant coastline
• concordant coastline


  bands of rock run parallel to the coastline
• headland


  rocks of higher resistance erode slower. as a result, high resistance rocks protrude out producing headlands
• bays


  formed in the same way as headland. constructive waves often bring sediment to form a beach.
• cliffs


  made through the process of hydraulic action and abrasion. destructive waves create a wave cut notch. as the notch gets eroded, the cliffs above become unstable, collapse, and are removed by waves
• wave cut platform


  below a wave cut notch, an area of exposed rock is left, which is not smooth. it continues to get eroded

  
• cave


  destructive waves break against the cliff face. hydraulic action widens the crack, eventually widening enough to form a cave
• arch


  waves erode the cave via abrasion and hydraulic action, which cause them to break through the middle of it forming an arch
• stack


  continued erosion on the base of the arch weakens it until the roof collapses, leaving a stack like Old Harry Dorset

  
• mechanical weathering-freeze thaw


  water enters cracks and in cold climates, freezes, expanding by around 10%. pressure weakens the cliff face.
• chemical weathering


  acid rain contains carbonic acid which dissolves limestone