Landforms

V-Shaped Valley and Interlocking Spurs Diagram

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V-shaped Valley- upper course

  • Form as a river flows downhill.
  • The rivers energy is focused on the river bed (vertical erosion).
  • As it gets deeper the valley sides are worn away through weathering.
  • This leaves steep valley sides, creating the V-shape.
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Interlocking Spurs- upper course

  • 'Pairs' of highland left either side of the valley.
  • These are created as the river winds around areas of harder rock to find the easiest route.
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Waterfall Diagram- upper course

Related image (http://www.geography.learnontheinternet.co.uk/images/rivers/waterfall.png)

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Waterfalls- upper course

  • A waterfall will form where hard rock overlays softer rock.
  • The river will erode the softer rock quicker, creating a 'step' in the river bed.
  • The water will then fall vertically from the hard rock to the soft rock below.
  • The hard rock is under cut, meaning it loses support and overhangs the drop.
  • Splash back causes hydraulic action to erode the rocks behind the fall of the water.
  • Hydraulic action and abrasion cause a plunge pool to form where water and load swirl around, eroding the rock futher.
  • The overhanging hard rock collapses into the plunge pool.
  • As the undercutting continues, a new overhang is created and the process repeats.
  • The waterfall retreats upstream leaving behind a gorge.
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Gorges- upper course

  • As the waterfall retreats upstream, it leaves a steep sided valley downstream called a gorge.
  • Every time the overhanging rock breaks off, the gorge retreats and grows longer.
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Meanders Diagram- middle course

Related image

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Meanders- middle course

  • The current is faster on the outside of the bend because the river channel is deeper (there's less friction to slow the water)
  • Therefore, more erosion takes place on the outside of the bend, forming river cliffs.
  • The current is slower on the inside of the bend because the river channel is shallower (there's more friction to slow the water down)
  • So eroded material is deposited on the inside of the bend, forming slip-off slopes.
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Ox-bow Lakes- middle course

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Ox-bow Lakes- middle course

  • Erosion causes the outside bends to get closer until there's only a small bit of land left between the bends (called the neck).
  • The river breaks through this land, usually during a flood, and the river flows along the shortest course.
  • Deposition eventually cuts off the meander forming an ox-bow lake.
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Flood Plains- lower course

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Flood Plains- lower course

  • The flood plain is the wide valley floor on either side of a river which occasionally gets flooded.
  • When a river floods onto the flood plain, the water slows down and deposits the eroded material that it's transporting. This builds up the flood plain (makes it higher).
  • Meanders migrate (move) across the flood plain, making it wider.
  • The deposition that happens on the slip-off slopes of meanders also builds up the flood plain.
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Levees- lower course

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Levees- lower course

  • Natural embankmets (raised areas) along the edges of a river channel.
  • During a flood, eroded material is deposited over the whole flood plain
  • The heaviest material is deposited closest to the river channel, because it gets dropped first when the river slows down.
  • Over time, the deposited material builds up, creating levees along the edges of the channel, e.g. along the Yellow River in China
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