Scree

Scree is a collection of broken rock fragments at the base of crags, mountain cliffs, volcanoes or valley shoulders that has accumulated through periodic rockfall from adjacent cliff faces. Landforms associated with these materials are often called talus deposits or stony accumulations. Talus deposits typically have a concave upwards form, where the maximum inclination corresponds to the angle of repose of the mean debris particle size. Scree is a subcategory of the broader debris class of colluvium: any collection of loose, unconsolidated sediments at the base of hillslopes. The exact definition of scree in the primary literature is somewhat relaxed, and it often overlaps with both talus and colluvium. Colluvium refers to sediments produced by nearly any means and transported downslope by gravity; scree refers to larger blocks and fragments of rock transported downslope.

Source: Wikipedia