Abstract. Château Cugny is an exceptional place where the actual cliffs evolution is quite rapid. Because of the frost action, considerable quantities of frost-rived nibble broke off the cliffs each year. The relative frequency of rock falls enables measurements to be made with simple installations. Two examples of the daily freeze-thaw cycle show the variations of the rock falls during the day according to the temperature's changes. Frequent rock falls contribute to Château Cugny's cliffs rapid scarp retreat.
These rock falls occur by a 2-stage process: first, the frost susceptible lower portion of the cliff breaks apart resulting in undermining of the overlying non frostsusceptible portion which subsequently breaks off and falls down.