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coasts+rivers - Coggle Diagram

- - - - The river flows over bands of less resistant (softer) and resistant (harder) rocks.
      - The less resistant rock is more quickly worn away due to differential
      - erosion
      - .
      - The river erodes the rocks in three main ways:
      - Hydraulic action – when the sheer force of the water gets into small cracks and breaks down the rock.
      - Corrasion – when the river bed and banks are eroded by the load hitting against them.
      - Corrosion – when the river water dissolves minerals from the rocks and washes them away.
      - The river undercuts the harder rock leaving an overhang which becomes unsupported and collapses into the
      - plunge pool
        
        below.
      - After the overhang falls, some of the rocks are swirled around by the river and this helps to form a deep plunge pool below the waterfall. The plunge pool is also deepened during times of high
      - discharge
        
        when hydraulic action is most powerful.
      - The waterfall is moved upstream, the process continues and a steep-sided gorge is cut back into the hillside.
    - - Rivers begin high up in the mountains so they flow quickly downhill eroding the landscape vertically.
      - The river cuts a deep notch down into the landscape using hydraulic action, when the sheer force of the water gets into small cracks and breaks down the sides of the river valley. Corrasion (abrasion) also occurs which is when the river bed and banks are eroded by the load hitting against them. Another type of erosion that happens is corrosion (solution), when the river water dissolves minerals from the rocks and washes them away.
      - As the river erodes downwards the sides of the valley are exposed to
      - freeze-thaw weathering
        
        which loosens the rocks (some of which will fall into the river) and steepens the valley sides.
      - The rocks which have fallen into the river assist the process of corrasion and this leads to further erosion.
      - The river transports the rocks downstream and the channel becomes wider and deeper creating a V-shaped valley between
      - interlocking spurs