Mass movement
Also called: Mass wasting · Topic: Geomorphic Processes: Weathering, Mass Movement, Erosion and Soil Formation · NCERT: Class 11, Ch 5 "Geomorphic Processes"
Meaning
Mass movement, also called mass wasting, is the movement of rock debris down a slope under the direct pull of gravity. No agent such as running water, a glacier or wind picks up and carries the debris, though the moving mass may carry some water or ice with it. Because of this, it is not erosion. Weathering helps mass movement, but it is not essential. Steep slopes, loose material, heavy rain and loss of vegetation make it more likely. It ranges from slow soil creep to sudden rock falls, and it is a major hazard in hill regions.
Example
The Himalayas are young, still tectonically active, and made of soft sedimentary rock on steep slopes, so mass movements are very frequent there. The ISRO-NRSC Landslide Atlas (2023) ranks Rudraprayag and Tehri Garhwal districts of Uttarakhand among the most exposed in India.
Don't confuse with
- Erosion: needs a moving agent (water, ice, wind, waves) to pick up and carry material. Mass movement is driven by gravity alone.
- Weathering: breaks rock in place, with no real movement. Mass movement moves material downslope.
Related concepts
- Activating causes of mass movement
- Soil creep
- Solifluction
- Mudflow
- Debris avalanche
- Slump
- Rockslide
- Rock fall