. "stable"@en . "318.0"^^ . "Coal. Stratified bedrock. Occurs onshore. Deposited during the Duckmantian Substage (Carboniferous Period) (318-314.75 Ma BP)."@en . "Heathen Coal (South Staffordshire)"@en . . "HEAC"@en . . "314.75"^^ . . . "Coal."@en . . "Heathen Coal (South Staffordshire)"@en . . .