Mass movements

• heaves

  • slow movement : soil particles are heaved to surface by wetting, heating and freezing of water
  • particles move perpendicular to surface and then fall under gravity once dried, cooled or water thawed
  • net movement is down the slope
  • produces terracettes
• Slumps

  • rotational movement along a curved slip plane
  • clay saturates and flows along slip plane
  • commonly occurs if base has been undercut
  • produces separate, jerky events
• Slides

  • entire mass of material moves along slip plane
  • material holds shape until hitting the slope bottom (detached block)
  • leaves scar and debris at the bottom
  • needs weak rock / steep slop / undercutting
• Falls

  • on steep slopes with bare rock faces and exposed joints
  • rocks detach and fall freely under gravity
  • contributes to retreat of rock faces
  • produces scree
• Flows

  • more continuous and smoother form of slump
  • higher water content allows them to occur on shallower slops
  • leaves scar and toe