coasts

• waves forming

  1. wind blows over the sea
  2. friction on water surface causes ripples
• distance wind blows across sea

  fetch
• bigger the fetch

  bigger the wave
• constructive waves

  storms far away

  low waves

  more swash than backwash
• destructive waves

  local storms

  waves close together

  more backwash than swash
• weathering

  the weakening or decay of rock due to action of weather, plants or animals
• mechanical- disintegration of rock

  freeze-thaw

  • water collects in cracks of rock
  • water freezes and expands
  • temp rise and water seeps deeper
  • repetition = rock fragments fall and collect as scree
• chemical - chemical changes

  carbonation

  • rainfall absorbs CO2 from air - acidic
  • contact with alkaline rocks
  • reaction where rocks slowly dissolve
• biological - flora and fauna

  plant roots grow in cracks

  and animals burrow
• mass movement

  sliding of weathered material under the influence of gravity
• rockfall

  rock breaks away due to freeze thaw
• landslide

  blocks of rock slide downhill
• mudflow

  saturated soil flows downhill
• rotational slip

  slump of saturated soil along curved surface
• erosion

  wearing away the landscape
• solution

  dissolving of soluble chemicals
• corrasion

  rock fragments picked up by sea thrown at cliffs
• abrasion

  sandpaper - pebbles grinding over rocky platform
• attrition

  rock knock against each other
• hydraulic power

  waves hit cliff
• transportation

  moving of the rocks
• solution

  dissolved chemicals
• suspension

  particles carried within water
• traction

  rolling
• saltation

  bouncing
• why is sediment deposited

  water slows down and waves lose their energy
• longshore drift

  movement of sediment depending on the direction the waves approach the coast as a result of prevailing wind
• waves approaching head on the beach

  sediment moves up and down
• waves approaching at an angle

  sediment moves in a zig-zag pattern
• factors affecting coastal landforms

  1. rock type
  2. geological structure
• headlands and bays

  tougher, resistant rock is eroded slowly forming headlands

  weaker rock erodes faster forming bays

  bays are sheltered, deposition occurs -> beach
• caves , arch , stack

  1. abrasion and hydraulic power widen fault -> cave
  2. erosion leads to arch
  3. arch enlarged and roof attacked by weathering
  4. leaves isolated stack
  5. stack erodes and leaves a stump
• wave-cut platforms - erosion

  waves break against a cliff

  erosion causes a wave-cut notch

  undercuts cliff

  repetition -> wave-cut platform
• beaches - deposition

  deposits of sand and shingle by constructive waves
• development of sand dunes - deposition

  1. dunes form around obstacles
  2. stabilised by vegetation (marram grass)
  3. decomposing vegetation fertilises sand
  4. ponds can form depressions
• spits and bars - deposition

  1. longshore drift transports sand across the coast
  2. change in shape of coastline
  3. spit grows from land out to sea
  4. spit exposed to changes in wind + wave direction causing it to curve
  5. saltmarsh forms in sheltered water
• sand dunes

  sand blown inwards and builds up
• swanage - south coast of england
• coastlines - swanage ?

  discordant and concordant
• famous erosion landform?

  old harry stack