In geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, solifluction, also known as soil fluction, is a type of mass wasting

Mass wasting

Mass wasting, also known as slope movement or mass movement, is the geomorphic process by which soil, regolith, and rock move downslope under the force of gravity. Types of mass wasting include creep, slides, flows, topples, and falls, each with its own characteristic features, and taking place...

 where waterlogged sediment

Sediment

Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....

 moves slowly downslope, over impermeable material. It occurs in periglacial

Periglacial

Periglacial is an adjective originally referring to places in the edges of glacial areas, but it has later been widely used in geomorphology to describe any place where geomorphic processes related to freezing of water occur...

 environments where melting during the warm season leads to water saturation in the thawed surface material (active layer

Active layer

In environments containing permafrost, the active layer is the top layer of soil that thaws during the summer and freezes again during the autumn. In all climates, whether they contain permafrost or not, the temperature in the lower levels of the soil will remain more stable than that at the...

), causing a form of downslope "flow" to occur. This "flow" is due to frost heave that occurs normal to the slope, as well as to small-scale slippage. Where the underlying ground is permanently frozen (permafrost

Permafrost

In geology, permafrost, cryotic soil or permafrost soil is soil at or below the freezing point of water for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of...

) the process is often called gelifluction

Gelifluction

Gelifluction, very similar to solifluction, describes the seasonal freeze-thaw action upon waterlogging topsoils which induces downslope movement. Gelifluction is prominent in periglacial regions where snow falls during six to eight months of the year...

.

Solifluction can occur on slopes as shallow as 0.5 degrees at a rate of between 0.5 and 15 cm per year. In Germany the solifluction deposits from the Younger Dryas

Younger Dryas

The Younger Dryas stadial, also referred to as the Big Freeze, was a geologically brief period of cold climatic conditions and drought between approximately 12.8 and 11.5 ka BP, or 12,800 and 11,500 years before present...

 are found to have a consistent thickness of 0.4–0.7 metres.

Downhill creep

Downhill creep

Downhill creep, or commonly just creep, is the slow downward progression of rock and soil down a low grade slope; it can also refer to slow deformation of such materials as a result of prolonged pressure and stress. Creep may appear to an observer to be continuous, but it really is the sum of...

is a similar process which is not dependent upon cycles of freezing.