river characteristics P1

• What landforms are formed and made together in the context of GCSE geography?

  Waterfalls and gorges
• Where do waterfalls form in relation to hard and soft rock?

  Where a river flows over hard rock followed by soft
• What process erodes softer rock more than hard rock?

  Hydraulic action and abrasion
• What feature is created in the river as softer rock erodes more than harder rock?

  A step
• What is a steep drop eventually created by erosion called?

  A waterfall
• How is the hard rock eventually affected by erosion at a waterfall?

  It is undercut
• What happens when the undercut hard rock becomes unsupported?

  It collapses
• What process occurs at the foot of the waterfall with the collapsed rocks?

  Abrasion
• What landform is created at the base of a waterfall by abrasion?

  A deep plunge pool
• What happens to the waterfall over time due to undercutting and collapses?

  It retreats
• What landform is left behind as a waterfall retreats?

  A steep-sided gorge
• In which part of the river course are interlocking spurs typically found?

  Upper course
• In the upper course of a river, what is the dominant type of erosion?

  Vertical
• What type of valley is created by vertical erosion in the upper course of a river?

  Steep-sided V-shaped valleys
• Why do rivers in the upper course wind around hillsides?

  They lack power to erode laterally
• What are the hillsides that interlock with each other called?

  Interlocking spurs
• How do collapsed rocks erode the soft rock at the foot of a waterfall?

  Via abrasion
• What do interlocking spurs resemble in their arrangement?

  A zip
• What are meanders?

  Large bends in a river
• In which part of the river course do meanders typically occur?

  Middle and lower courses
• What are the four steps in meander formation?

  • Current faster on outer bends: deeper channel, more erosion.
  • Erosion forms River Cliffs on outside bends.
  • Current slower on inside bends: shallower, deposition occurs.
  • Deposition forms slip-off slopes inside bends.
• Why is the current faster on the outer bends of a meander?

  The river channel is deeper
• What landform is created by erosion on the outer bends of meanders?

  River Cliffs
• Why is the current slower on the inside of a meander bend?

  The river is shallower
• What landform is created by deposition on the inside of meander bends?

  Slip-off slopes
• What happens to meanders over time?

  They get larger and larger
• What can meanders eventually turn into?

  Oxbow lakes
• How do oxbow lakes form?

  • Erosion makes outside bends get closer.
  • Small bit of land left between bends.
  • River breaks through during a flood.
  • River flows along the shortest course.
  • Deposition cuts off the meander.
• What event typically causes a river to break through the small bit of land between meander bends?

  A flood
• What process cuts off the meander to form an oxbow lake?

  Deposition
• What eventually happens to oxbow lakes?

  They dry up back into land
• What landform is described as wide valley floors on either side of a river that occasionally floods?

  Floodplains
• Why do rivers deposit material on floodplains during floods?

  The water slows down and loses energy
• What process leads to the buildup of floodplains?

  The deposition of transported material
• What landform is formed by repeated flooding of a river, resulting in the deposition of coarse material near the riverbanks?

  Levees
• How does repeated flooding contribute to the formation of levees?

  Coarse material is deposited close to banks
• What is the term for the area where a river meets the sea?

  Estuary
• Why is the river in an estuary tidal?

  Because it meets the sea
• What happens to the volume of water in an estuary when the sea retreats?

  It is reduced
• What landform is created by the deposition of silt in an estuary?

  Mud flats