Mass movement

Mass movement is the process by which material flows down a slope as a result of gravity. It is one of the sub-aerial processes alongside weathering. These processes wear down a cliff from above. Along with the marine erosion processes, mass movement can cause cliff retreat.

There are four main types of mass movement:

1. Falls
2. Slides
3. Flows and creeps
4. Rotational slumps

1. Falls occur where there is loose material from rocks perhaps from weathering such as freeze-thaw and root penetration.  The material falls down the steep cliff face and collects at the bottom. A lot of debris accumulates at the base of the cliff.

2. Slides occur when blocks of material slide down the sloping cliff face. There is little deposition at the base of the cliff.

3. Flows and creeps happen when there is water in the soil or a stream nearby. The water loosens the soil and the material slowly flows down the slope where it collects at the base of the plain.

4. Rotational slumps typically occur where there is soft rock. The material slips and spills onto other layers of rock. The plain here is curved.