Factors affecting rate of erosion: coastal processes

• What is hydraulic action

  The sheer force of the water impacting upon rocks (without debris)
• What is abrasion


  This is the wearing away of the cliffs by sand, shingle (pebbles) and boulders hurled against them by waves.
• What is attrition


  Waves bash pebbles into each other making them smaller and more round in shape
• What is wave quarrying/ cavitation

  Parcels of air are trapped & compressed in joints & cracks in cliff face, when wave retreats air is released explosively. Over time this weakens the rock & causes pieces to break away.
• What is solution


  Includes dissolving limestone by carbonic acid in the sea water & the corrosion of other rocks by action of salt in sea water.
• What is denudation


  The combined action of weathering, mass movement and erosion
• Erosion definition


  Breakdown of rocks as a result of an agent of erosion (water, ice and wind)
• Weathering definition


  Breakdown of rocks in situ at or near the earth's surface through direct contact with earth's atmosphere
• Mass movement definition


  Downslope movement of rock under the force of gravity
• What factors affect rate of erosion

  - Wave steepness- steeper waves are higher-energy wave and have a greater erosive power than low-energy waves

  - Sea depth- steep,y shelving sea bed at coast will create higher and steeper waves

  - Beach presence- beaches absorb wave energy and can therefore provide protection against marine erosion.

  
  

  These are just a few examples
• What is differential erosion

  Variation in the rate at which rocks wear away is called differential erosion
• Different rock structure


  Concordat coastlines (different rock types lie parallel to coastline) tend to be fairly 'straight'

  whereas discordant coastlines (different rock type lie perpendicular to coast) tend to have headlands and bays
• Discordant coastlines


  Have alternating bands of hard and soft rock at 90° to coast

  Erosional land forms are most common bc erosion happens at diff times due to soft and hard rock
• Concordat coastlines


  Have alternative bands of hard and soft rock parallel to coast