River landforms

River landforms

1. Erosional

   • Waterfalls
     • Softer rock is eroded more than the hard rock - creating 'step'
       • Eventually creates steep drop
         • Hard rock collapses as unsupported
           • Plunge pool created by collapsed rock - swirls around and erodes bottom
   • Gorges
     • When a waterfall completely retreats
   • Interlocking spurs
     • Rivers aren't powerful enough to erode sideways
       • Have to wind round hillsides
         • Hillsides that interlock as river winds round them

2. Erosional and depositional

   • Meanders
     • Current is faster on outside
       • So more erosion
     • Current is slower on inside
       • So eroded material deposited
   • Oxbow lake
     • Outside bends get closer (erosion)
       • Only small bit of land left - neck
     • River breaks through
       • River flows along shortest route
     • Deposition cuts off the meander
     • Form from meanders

3. Depositional

   • Flood plains
     • Wide valley floor on ether side of river
     • When river floods it deposits eroded material
       • Builds up - makes it higher
   • Leeves
     • Natural embankments
     • Heaviest material deposited closest to river (dropped first)
   • Deltas
     • Material builds up forming low lying land
     • Rivers slow down when meet sea or lake - deposit material