coasts

• Littoral zone 


  area of land between cliffs on the coast and offshore area beyond the influence of waves
• coastal inputs


  waves, tides, sun, wind speed
• coastal outputs


  ocean currents, evapouration
• coastal stores


  beaches, sand dunes, spits, bars, caves
• coastal transfers


  erosion, transportation, deposition, weathering
• terrestrial supplies of sediment

  debris from cliff collapse, aeolian deposition and artificial replacement by humans
• offshore supplies of sediment

  transported seabed material from waves, fine sediment from river bed
• dynamic equilibrium


  system is in balance from year to year buy slower underlying changes also occur
• macromareal tides


  larger intertidal range
• intertidal range


  range between high tide and low tide
• micromareal tides


  lower intertidal range of less than 2m
• spring tides


  high tides are higher and low tides are lower than average
• neap tides


  weaker tides than usual
• diurnal changes


  daily change
• constructive waves


  has strong swash

  deposits sediment

  sandy beaches

  shorter fetch

  6-8 waves per minute
• destructive waves 


  weak swash

  strong backwash

  steep profile beaches

  shingle beaches

  10-14 waves per minute
• what are subaerial processes


  land based process that occur above the water line
• name subaerial processes


  freeze thaw

  biological weathering

  chemical weathering

  rockfalls

  soil creep

  landslides

  rotational cliff slumping
• wave cut notch and platform


  High energy event

  erosion concentrated around high tide line creating wave cut notch

  notch gets deeper and cliff face becomes unstable and collapses

  leaves behind platform of unaffected cliff base

  over time wave cut platform is created
• rockfalls


  high energy event

  rocks drop vertically due to erosion and weathering

  process takes seconds
• clay cliff slumping 


  high energy event

  when it rains clay gets heavy

  waves attacking the cliff foot weaken it and causes slumping from the clay above the cliff foot

  process takes months to years
• tombolo


  low energy event

  bar that connects the mainland to offshore island

  formed due to wave refraction off the coastal island reducing wave velocity
• formation of sand dunes

  embryo - close to sea, grass captures sand

  fore dune - maram grass traps more sand

  main ridge - exposed to wind, long rooted plants bind the sand

  dune slack - dips in dunes where water collects

  grey dune - sheltered from wind more vegetation takes root
• wave refraction


  when wave direction approaching the shoreline is modified due to shape of sea bed

  shallow water friction causes deceleration of waves
• confused sea 


  ripples make water surface rough and gives wind better grip

  waves become steeper and choppy
• wave reflection


  change of direction of a wave when it meets a boundary
• igneous rocks


  e.g granite

  strong and resistant to different processes of erosion
• sedimentary rocks


  e.g chalk and limestone

  attacked chemically by weak acids and dissolves in rain and seawater
• joints 


  breaks in rocks created without displacement

  increases erosion rates as crack created and hydraulic action can exploit this
• faulting


  major fractures in rocks
• freeze thaw


  trapped water freezes and expands
• salt crystallization


  salty water evaporates and leave crystallized salt
• blowholes


  sea caves grow landwards and upwards into vertical shafts

  incoming waves force air to rush upward and water to spout
• attrition


  pebbles banging against each other
• abrasion 


  pebbles rub against each other and become smaller and rounded
• estuaries


  where the river meets the sea

  when the sea retreats the volume of water is reduced and this allows deposits of silt forming mudflats
• deltas


  this forms when inputs of material exceed the rate they are being removed
• flocculation


  when salt water mixes with freshwater in deltas
• solution


  minerals dissolved and carried by sea water
• suspension 


  small sized sediments moved by waves