"stable"@en . . "Coal. Stratified bedrock. Occurs onshore. Deposited during the Duckmantian Substage (Carboniferous Period) (318-314.75 Ma BP)."@en . . "314.75"^^ . "Coal."@en . . . "2F9RC"@en . . "Two-Feet-Nine Rider Coal (South Wales)"@en . . . "318.0"^^ . . "Two-Feet-Nine Rider Coal (South Wales)"@en .