1911 Encyclopædia Britannica/Cataclysm

CATACLYSM (Gr. κατακλυσμός, a deluge), a great flood or deluge (q.v.). The term is used in geology to denote an overwhelming catastrophe which has produced sudden changes in the earth’s surface; and also, figuratively, of any great and violent change which sweeps away the existing social or political order.