The set of mechanisms that operate at and near the Earth’s land surface, breaking down and transferring rock material and consequently fashioning land-forms at small and medium scales. Processes operating on the surface are termed ‘exogenetic’; those originating below the surface ‘endogenetic’. Two categories may be recognized: (a) zonal processes, which are broadly controlled by climate (e.g. the work of glaciers); and (b) azonal processes, which operate on a world-wide basis (e.g. fluvial processes). The rate at which such processes operate may be measured by direct field recording or by making use of historical records. See erosion rate.