DILUVIUM, 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 (Lat. for "deluge," from diluere, to wash away) was formerly given to the "boulder clay" depOsits, supposed to have been caused by the Noachian deluge. In this sense it still lingers on the continent of Europe, but it has dis appeared from British geological literature.