Sandfall

A sandfall (sand fall or grainfall) is term applied to a variety of forms of sedimentary transport or sedimentary features. One form is the sand equivalent of waterfalls and these can be found under dry, desert conditions or in submarine conditions. The sand either falls vertically over suitable drops or cascades down hard slopes in the same way as water cataracts. Sandfalls are found in sandstone canyons such as Antelope Canyon^{[citation needed]}, and are driven by wind and gravitational forces. The same process occurs in submarine environments driven by water currents and gravity. Sandfalls in the submarine San Lucas Canyon off Cabo San Lucas, Baja California were famously dived by Jacques Cousteau. Carter (1975) argues that the ubiquity of this process is evident from the examples from the sides of submarine canyons documented by Dill (1964) and from sea-mounts and deep-sea trenches documented by Heezen and Holhster (1971).^{[1][2][3][4][5][6][7]}

Sandfalls can also be "dry sandflows cascading down the escarpment face, where the grain concentration decreases dramatically and the streaming component of stress greatly exceeds the collisional component" ^[8] or "The steeply sloping surface on the lee side of a dune standing at or near the angle of repose of loose sand and advancing downwind by a succession of slides wherever that angle is exceeded" ^[9]

The process of sand falling like rain has also been refred to as a sandfall.^[10][11]

Strictly gravitational sandfalls belong to the large category of mass wasting, which includes all erosional movement under gravity of the materials making up the Earth's crust. The sand flow on the leeward slope of sand dunes involves slipping or sliding of sandgrains, and does not involve falling.^{[citation needed]}