( n. )
Mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations.
( n. )
Mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012