Rivers

• The journey of a river

  source: place where a river begins
• confluence: Point where a river joins a larger one
• Estuary- part of the river mouth that is tidal
• Processes of a River

  1. Erosion

  2. Transport

  3. Deposit
• The river wears away the landscape
• The river carries the eroded material away
• The river drops the material it is carrying
• River Erosion


  The river crudes the landscape using many processes
• Hydraulic action


  The fast moving water breaks and wears away material from the bed and banks of the river
• Load


  The broke material that is now carried along by the river
• Abrasion


  The load is thrown against the bed and banks of the river and wears them down
• Attrition


  The load itself is broken down further as particles bounce off one another and become smooth and rounded
• Solution


  The water can dissolve some of the minerals, e.g. limestone, on the river bed and banks
• Minerals are dissolved in the water and carried along
• The impact of the rock grains hitting off one another
• delta - a fan shaped area of land found at the mouth of a river
• Mouth - place where the river enters the sea
• River basin - the land that water flows across or under on its way to a river
• Flood plain - area that gets covered with water when the river floods
• tributary - a stream or river that joins a larger river
• River Transportation


  Load is transported in a number of ways by the river
• Traction


  Large pebbles and stones are rolled and dragged along the river bed by the force of the water
• Saltation


  Small pebbles are bounced along the river bed
• Suspension

  Tiny particles are held in suspension in the water - the movement of water is fast enough to keep them from dropping to the river bed
• Solution


  Dissolved minerals like limestone is carried in solution - it cannot be seen
• Methods of river load transport

  • Rolling (Traction)
  • Bouncing (Saltation)
  • Suspension
  • Solution
• River Deposition


  Rivers deposit or drop their load when they begin to slow down and lose energy
• When rivers deposit their load


  • When a river reaches flat ground
  • When a river enters a lake or the sea
  • At the inside bend of a meander
• From smallest to largest particle size, the ways a river transports its load are: Solution, Bouncing, Rolling, Suspension
• Waterfall

  A river flowing over a vertical slope, a feature of erosion
• Waterfall


  • Powerscourt Waterfall, Co. Wicklow
• Waterfall


  • Hard rock lies on top of an area of soft rock
  • River erodes the soft rock faster
  • Develops a vertical drop where the hard rock and soft rock meet
  • Plunge pool develops at the base due to the force of the falling water
  • Rock above the plunge pool is undercut and collapses into the pool
  • Waterfall slowly erodes its way upstream
• Formation of a waterfall


  1. River flows over an area where hard rock lies on top of soft rock

  2. River erodes the soft rock faster, developing a vertical drop. this drop is called a waterfall

  3. Plunge pool develops at the base due to the force of the falling water

  4. Rock above the plunge pool is undercut and collapses into the pool

  5. Waterfall slowly erodes its way upstream
• Waterfalls are a feature of erosion
• Delta


  A fan-shaped area of land found at the mouth of a river, a feature of river deposition
• Formation of a delta


  1. River reaches a lake or sea

  2. River slows down and loses power to carry sediment

  3. Sediment dropped at river mouth

  4. Sediment deposits build up over time

  5. River breaks through delta in many small channels called distributaries
• When a river reaches a lake or the sea, it slows down and loses the power to carry sediment
• The sediment is then dropped at the mouth of the river
• Some rivers drop so much sediment that waves and tides can't carry it all away, forming the delta
• The large deposits build up over time at the mouth of the river and block the river's entry to the sea