Mass Movements

It is the movement of weathered materials down the slope due to gravitational forces.

The movement may be gradual or sudden, depending on the gradient of the slope, the weight of weathered debris, presence of lubricating moisture, etc.
Mass movements are aided by gravity and no geomorphic agent like running water, glaciers, wind, waves and currents participate in the process of mass movements.

Several kinds of mass movements are:

SOIL CREEP:

This is slow, gradual but continuous movement of soil down the hill slope.
It is not very noticeable especially when the slope is gentle or the soil is covered with vegetation.
It is most common in damp soils where water act as a lubricant.

SOIL FLOW/SOLIFLUCTION:

When the soil is completely saturated with water, the individual particles are completely suspended in water and move easily over one another and over the underlying rocks. The soil acts like a liquid and soil flow or a mudflow occurs.
In arid regions, a mantle of weathered materials may become saturated after a storm and flow downslope as a semisolid mass.
In temperate and tundra regions, soil flow occurs when the surface layers of a frozen ground thaw in spring.

LANDSLIDES (SLUMPING/SLIDING):

These are very rapid kind of movements and occur when a large mass of soil or rockfall suddenly.
They usually occur on steep slopes such as in mountain or a cliff.
Earthquakes, volcanic disturbances, man-made steepening can all result in landslides.
Slumping occurs where permeable rock layers overlie impermeable strata like clay. Water percolates through the permeable layers and is halted by clay which acts as a slippery surface over which the upper layers slide.