lithify

[ lith-uh-fahy ]
/ ˈlɪθ əˌfaɪ /

verb (used with object), lith·i·fied, lith·i·fy·ing.

to change (sediment) to stone or rock.

verb (used without object), lith·i·fied, lith·i·fy·ing.

to become lithified.

Origin of lithify