Rivers

• weathering


  breakdown and decay of rock by natural processes - in situ
• 3 types of weathering


  mechanical, chemical, biological
• mechanical wethering


  freezethaw
• chemical weathering

  acid rain - falls on rocks and reacts with weak minerals causing the, to dissolve and the rock to decay
• biological weathering

  roots of plants can grow into trees and split the rock apart
• mass movement definition

  movement of soil and rocks downslope die to gravity
• 3 types of mass movent

  soil creep, sliding(landslide), flows
• soil creep

  individual particles of soil move slowly down a slope
• sliding


  material moves rapidly downslope on one go (e.g landslide)
• flows

  masses of soil or rock usually mixed with water flow downhill
• 4 methods of river transportation

  traction, saltation, suspension, solution
• traction


  large boulders roll along the river bed
• saltation


  smaller stones bounce along the river bed
• suspension


  finer particles carried in the river body (muddy water)
• solution

  soluble rocks dissolve in the water and are carried along in the water
• vertical erosion


  river is eroding in a downwards movement in upper course forming v-shaped valleys
• lateral erosion


  river erodes sideways (middle and lower course). widens river channel
• 4 types of erosion

  hydraulic action, abrasion, attrition, solution
• hydraulic action


  sheer force of the water hitting the river bed and banks wearing them away
• abrasion

  material carried by the river wears away the bed and banks
• attrition


  sediment particles carried in the water collide with each other, knocking edges off. overtime causing them to become smaller and rounder
• solution (erosion)


  river water is slightly acidic so it dissolves some rocks (limestone and chalk)