Variety of landslide characterized by movement along a concave-up failure surface, so the moving material partly rotates about an axis at right angles to the slope. Typically, the upper part of the block fractures into a series of scarps arranged like steps tilted backward, and the lower part (toe) forms a fan-shaped bulge covered with radial cracks and ridges. Surface water may be retained in the depressed zone. The slump may be caused by basal undercutting, or by the over-steepening of artificial embankments. It is normally found in a uniform, relatively weak material, e.g. clay.

Rotational slip