The term extreme rainfall refers to an event during which the thresholds of various hydrological and geomorphic processes are exceeded. The frequency of extremes varies in different climatic zones and in time. The clustering of extreme events happens when the extremes are repeated every 2–3 years, every year or even several times a year. Such clusterings disturb the equilibrium of slope and river channel systems and are separated by periods of stability and recovery. The occurences of clusters are exemplified by present – day processes, historical records and geological records. On this base a model of phases with frequent and rare clusterings during the Holocene was constructed.