Diluvium

thumb|upright=1.15| Diluvial terraces on Katun River Altai Scabland, [[Altai Republic]] thumb|Giant current ripples in the Kuray Basin, Altai, Russia

Diluvium is an archaic term applied during the 1800s to widespread surficial deposits of sediments that could not be explained by the historic action of rivers and seas. Diluvium was initially argued to have been deposited by the action of extraordinary floods of vast extent, specifically the Noachian Flood.