Thursday, 26 March 2015

CHANNEL PROCESSES-Erosion processes

Abrasion
  • Scraping, scouring and rubbing action - materials carried along by a river (load). 
  • Rivers carry rock fragments in the flow of the water + drag them along the bed= wear away the banks and bed of the river channel.


Hydraulic action
  • Sheer power of moving water. 
  •  Movement of loose unconsolidated material - frictional drag of the moving water on sediment lying on the channel bed.


Corrosion
  • Rocks that contain carbonates, such as limestone and chalk. 
  • Minerals = dissolved by weak acids in the river water + carried away in solution.


Attrition

  • Reduction in the size of fragments and particles within a river due to the processes describe above. 
  • Fragments strike one another as well as the river bed. 
  • Become smoother, smaller + more rounded as they move along the river channel. 

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