Large bedrock landslides have been identified on dip slopes of the Appalachian Valley and Ridge province of eastern North America. These landslides include rock block slides, rock slumps, rock slides, rock avalanches, and gravitational sags (sackung) and are the largest known in this area. Single landslides may involve more than one billion cubic meters of rock. The large bedrock landslides are weathered and most likely Quaternary in age. The present distribution of the large failures may be due to changes in the rock types present on dip slopes as well as proximity to major drainages and seismic zones. Little evidence is available to suggest movements of this magnitude during historic times. However, because such large slope failures constitute a significant hazard to life and man-made structures, it is important to know where, why, and how they have occurred.