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How does a translational slide move downhill?

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landslide This 1995 landslide at La Conchita, a coastal town in California, swept away a hillside road and destroyed a number of houses.

A translational slide moves downhill by displacing material along one or more discrete, broadly planar shearing surfaces. Unlike rotational slides, which move along concave-upward surfaces, translational movement typically follows existing structural features, such as a bedding plane or the interface between resistant bedrock and weaker overlying material.1

If the overlying material remains a single, little-deformed mass during this process, it is specifically referred to as a block slide. In some cases, particularly when occurring along gently sloping shear planes in fine-grained rocks like fissured clays, the displaced mass may become fluidized by an increase in pore water pressure, at which point the movement is sometimes called a mud slide.1