rockfall

thumb|upright=1.35|Rockfall deposit, Afghanistan A rockfall or rock-fall is a quantity of rock that has fallen from a cliff face or from the roof or walls of mine or quarry workings.

==Causal mechanisms== thumb|A Loader (equipment)|front-end loader clearing fallen rocks from the Zion-Mount Carmel Highway, [[Utah, USA]] Favourable geology and climate are the principal causal mechanisms of rockfall, factors that include intact condition of the rock mass, discontinuities within the rockmass, weathering susceptibility, ground and surface water, freeze-thaw, root-wedging, and external stresses. A tree may be blown by the wind, and this causes a pressure at the root level and this loosens rocks and can trigger a fall. The pieces of rock collect at the bottom creating a talus or scree. Rocks falling from the cliff may dislodge other rocks and serve to create another mass wasting process, for example an avalanche.