erosional landforms

  • Created by: beaw18
  • Created on: 23-04-19 13:47

cliffs and shore platforms

  • undercutting occurs when destructive waves break repeatedly on sloping coastlines, erosion causes a wave-cut notch
    • if continued, upper cliff collapsed due to lack of base support - steep profile and a cliff
    • wave cut platform - area of rock at base of cliff
      • boulders or large pieces of rock can accumulate on platform if too large to be removed by waves
  • cliff retreat occurs when this process occurs parallel to the coast
  • cliff profiles vary due to geology
  • wave cut platforms reduce pressure on cliffs, as waves break on platform and not on cliff base, undercutting eventually ceases
  • weathering processes important on platform development - solution, freeze-thaw and salt crystalisation may take place
  • marine organisms such as algae increase chemical weathering - photosynthesis releases CO2, mixes with salt water, more acidic
  • at high and low tide erosion levels are greatest as water levels are more constant
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headlands and bays

  • form adjacent to eachother due to bands of rock differing in erosion resistance 
  • weaker rocks erode more quickly and cause bays, more resistant rocks slowly and so stick out as headlands 
  • causes formation of a discordant coastline 
  • width of bay determined by width of weaker rock band 
  • rocks which lie parallel to coast produce concordant coastline
    • if more resistant rock faces the sea, it will protect weaker rocks from erosion, resulting in a straight and even coast line
    • bays and headlands may still occur due to the erosion of weaker areas such as fault lines
  • wave refraction takes place at more irregularly shaped coastlines - means that headlands get more wave action erosion than bays
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geos and blowholes

  • geo - narrow, steep-sided inle
  • occurs at lines of weakness in coastline, such as joints and faults
  • weak points eroded more rapidly by wave action than more resistant rock surrounding them
  • hydraulic action forces air and water into joints and weakens it
  • when the roof of the cliff above the geo collapses it becomes a blowhole
    • when waves enter, water is pushed out the top violently, causing it to look similar to a whale's blowhole
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caves, arches, stacks and stumps

  • erosional sequence which takes place, beginning with a headland
  • cracks/faults in cliffs are eroded by wave action
  • this then becomes widened into a cave
  • when the otherside of cliff is broken through (back of the cave), this then becomes an arch
  • the roof of the arch eventually collapses due to widening nature of erosion, making a stack
  • stack becomes smaller and smaller due to erosion and becomes a stump
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