Types of mass movement

Types of mass movement

1. Slide

   • Has distinct zone of weakness
     • Separates slide material from more stable underlying material
   • Discrete sliding pane
   • Cohesive mass, without internal deformation, moves downslope
     • Whole mass moves at same speed at each depth from surface
   • Little to no water involved
     • Slide is a very dry or unsaturated mass of weathered product
   • Has either planar or rotational sliding plane

2. Flow

   • No sharply defined failure surface
   • Shear stress distributed unequally throughout mass
   • Thick regolith because of high amount of retained moisture
     • High amount of water involved
       • Unconsolidated weathered material
   • Max velocity at/just below ground surface
   • Rate of flow diminish sharply with depth to zero at junction between regolith and solid rock
     • Solid rock more stable, angular, less mobile

3. Heave

   • Smaller scale of mass movement, less catastrophic
   • Results from repeated expansion and contraction of soil + influence of gravity
     • Due to differential heating, freeze thaw
   • Expands perpendicular to ground surface
   • Contracts generally vertically due to gravity