Mass movements are the downslope movement of rock, soil, and sediment due to gravity. They include rockfalls, rockslides, slumps, mudflows, earthflows, and creep. Mass movements are triggered by factors like saturation, steep slopes, removal of vegetation, and earthquakes. Geologists classify mass movements based on the material type, movement style, and speed.

1. 5.3 Mass Movements

2. Mass movement
• The downslope movement of
rock, regolith, and soil under the direct
influence of gravity

3. rockfall
• Occurs when rocks or rock fragments fall
freely through the air; common on steep
slopes

4. rockslide
• Occurs when a mass of rock slides rapidly
downslope along planes of weakness

5. slump
• The downward slipping of a mass of rock or
unconsolidated material moving as

6. mudflow
• Quickly moving downhill flow of soil and rock
fragments containing a large amount of water

7. earthflow
• Slow- moving downslope movement of water-
saturated, clay-rich sediment, most
characteristics of humid regions

8. Creep
• The slow downhill movement of soil and
regolith

9. Key Concept
• The transfer of rock and soil downslope due to
gravity is called mass movements.

10. Key Concept
• Among the factors that commonly trigger
mass movements are saturation of surface
materials with water, oversteepening of
slopes, removal of vegetation, and
earthquakes.

11. Key Concept
• Geologists classify mass movements based on
the kind of material that moves, how it
moves, and the speed of movement.