River terms

• Source 


  The start of the river - Usually in high areas, very shallow and thin as they have a large gradient and not enough discharge to grow
• Drainage basin 


  The area of land drained by a river and its tributaries - no water in ground as it all flows down the valley and into the river
• Confluence 


  Where a tributary joins a larger river - increase of discharge
• Mouth 


  The end of a river (Usually where it joins the sea) - Where estuaries occur, tidal areas
• Water shed 


  The edge of a river basin
• Tributary 


  A small stream that joins a larger river
• Upper course 


  Thin and shallow river as the gradient is large so water cannot build up, Straight river as not enough force for erosion, interlocking spurs occur here.
• Middle course 


  Meanders and oxbow lakes occur here as gradient is lower so the water build up and erodes the sides of the river. Wider and a bit deeper than the upper course
• Lower course 


  Very wide and deep, flood plains and levees occur here as it is so flat. Lots of deposition occurs here as it has little energy
• Attrition 


  Rocks collide with each other in the river and breaks them down into smaller pieces
• Hydraulic action 


  Water compresses air into the cracks of a river bank and increases pressure so the cracks grow bigger.
• Solution 


  Water is slightly acidic and dissolves some types of rock on the bed and banks
• Abrasion 


  Rocks carried by the river scrape and rub along the banks and bed which wears them down
• Interlocking spurs

  Step 1: Very steep V-shaped valley takes up valley floor

  Step 2: Freeze thaw weathering widens valley
• What types of rock are involved in the formation of waterfalls?

  Hard rock and soft rock
• How does erosion affect the soft rock at waterfalls?


  Erosion breaks down the soft rock
• What process wears away the soft rock at waterfalls?

  Hydraulic action
• Why does the soft rock erode faster than the hard rock at waterfalls?


  It is less resistant than the hard rock
• What happens to the hard rock as the soft rock erodes away?

  The hard rock becomes unsupported and collapses
• What happens to rocks that fall from the waterfall?

  They are transported down the river or stay in the plunge pool
• What is the result of the erosional processes at a waterfall?

  The river retreats backwards
• What geographical feature is left behind after a waterfall retreats?

  A steep sided gorge