Mass wasting

Mass wasting, also known as mass movement, is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in a moving medium, such as water, wind, or ice. Types of mass wasting include creep, solifluction, rockfalls, debris flows, and landslides, each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth, Mars, Venus, Jupiter's moon Io, and on many other bodies in the Solar System. Subsidence is sometimes regarded as a form of mass wasting. A distinction is then made between mass wasting by subsidence, which involves little horizontal movement, and mass wasting by slope movement. Rapid mass wasting events, such as landslides, can be deadly and destructive. More gradual mass wasting, such as soil creep, poses challenges to civil engineering, as creep can deform roadways and structures and break pipelines. Mitigation methods include slope stabilization, construction of walls, catchment dams, or other structures to contain rockfall or debris flows, afforestation, or improved drainage of source areas. Mass wasting is a general term for any process of erosion that is driven by gravity and in which the transported soil and rock is not entrained in a moving medium, such as water, wind, or ice. The presence of water usually aids mass wasting, but the water is not abundant enough to be regarded as a transporting medium. Thus, the distinction between mass wasting and stream erosion lies between a mudflow (mass wasting) and a very muddy stream (stream erosion), without a sharp dividing line. Many forms of mass wasting are recognized, each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Based on how the soil, regolith or rock moves downslope as a whole, mass movements can be broadly classified as either creeps or landslides.