coasts done!

• What is the littoral zone?


  near shore area where sunlight penetrates all the way to the sediment and allows aquatic plants to grow
• how do coastal zones develop

  by wind, waves and currents
• what types of landscapes are there


  rocky, sandy and estuarine
• what zones are there in the littoral zone

  backshore, foreshore and nearshore
• Backshore


  waves only reach this area during extremely high tides
• nearshore


  the region closest to the sea
• offshore


  the sea.
• Long term criteria for the way coasts change

  - Geology

  - Sea Level Change
• short term processes


  inputs from riversm waves and tides (deposition)
• rocky coast erosional features


  mechanical wave action

  abrasion

  mass movement
• where do rocky coasts occur

  in high energy environments , where erosion can happen.
• where + why do estuarine and sandy coasts occur


  -low relief areas

  
  

  -they result from the input of sediments from offshore sources such as rivers.
• what is a sediment cell


  no inputs or outputs, they are an almost closed system
• what is a source?


  where the sediment originates from, e.g. cliffs or offshore bars.
• what is a through flow


  the movement of sediment along the shore via longshore drift
• positive feedback loop


  Positive feedback is then when an action leads to something becoming MORE than it was before;
• example of positive feeback

  people walking on sand dunes reduces vegetation, which holds the sand together, making it more susceptible to erosion.
• negative feedback


  when destructive waves from a storm lose energy, sediment is deposited in an offshore bar. the bar protects the coastline, making a coastline go back to normal after a storm, which may have eroded the coastline.
• What is eriosion


  the removal of sediment from a coastline
• HAAC


  hydraulic action

  attrition

  abrasion

  corrosion
• hydraulic action


  as a wave crashes into a rock/cliff, air is forced into cracks, adding pressure. causes the rocks to shatter.
• Corrosion (solution)


  water dissolves minerals from the rocks and washes it away as its so small
• abrasion


  eroded water particles scrape and rub against the rocks, removing small pieces.
• attrition


  eroded particles in water collide with eachother and break into smaller fragments. this causes their edges to become rounded as they rub together.
• When are erosion rates highest?


  -when waves have a long fetch (powerful)

  -type of wave (destructive=powerful)

  -weak rock (sedimentary)

  -the geology of a rock (what's the structure like, are there cracks and fissures)

  -strata (what angle is the rock facing)
• Coastal Landforms (3)


  wave cut notches

  wave cut platforms

  cave,arch,stack,stump
• wave cut platform


  bottom of cliff is eroded, causing the rest of it to collapse, only leaving the bottom part.
• wave cut notch


  the stage before a wave cut platform has collapsed
• Cave-Arch-Stack-Stump


  Sequence: Caves, arches and stacks form from eroded headlands (narrow piece of land that projects from a coastline). As waves crash into headlands, hydraulic action and abrasion causes enlargement of cracks in rocks. Continued erosion deepens cracks into caves which can eventually turn into arches. When these arches collapse, due to erosion, they form a stack of isolated rock. Over time, the base of the stack will in turn become eroded, and the stack will collapse into a stump.
• LSD


  Waves hit the beach at an angle determined by the direction of the prevailing wind.

  ● The waves push sediment in this direction and up the beach in the swash.

  ● Due to gravity, the wave then carries sediment back down the beach in the backwash.

  ● This moves sediment along the beach over time.
• what other processes of transportation are there

  traction, saltation, suspension, solution
• traction


  Large, heavy sediment rolls along the sea bed, being pushed by currents.
• Saltation


  Smaller sediment bounces along the sea bed, being pushed by currents.
• suspension


  Small sediment is carried within the water
• solution


  dissolved material is carried in the water
• When does deposition occur?


  when a wave loses energy meaning the sediment becomes too heavy to carry.

  a wave does not drop all of its sediment at once, it is a gradual process.
• Flocculation


  clay particles clump together when mixed due to chemical attraction, then sink due to their high density.
• depositional landforms


  spits, bars, tombolos, cuspate forelands, offshore bars, sand dunes,
• Spits


  Beaches which stick out into the sea. They form at sharp bends on coastlines where longshore drift transports sand and shingle past the bend and deposits it in the sea. Strong winds can make it curve.
• bars


  Forms when a spit joins two headlands together, cutting of the sea from the water trapped between the bar and the coastline. This forms a lagoon. Also known as a Barrier Beach.