1911 Encyclopædia Britannica/Diluvium
DILUVIUM (Lat. for “deluge,” from diluere, to wash away), a term in geology for superficial deposits formed by flood-like operations of water, and so contrasted with alluvium (q.v.) or alluvial deposits formed by slow and steady aqueous agencies. The term was formerly given to the “boulder clay” deposits, supposed to have been caused by the Noachian deluge.