"Coal. Stratified bedrock. Occurs onshore. Deposited during the Marsdenian Substage (Carboniferous Period) (321.5-320 Ma BP)."@en . . "321.5"^^ . "Coal."@en . "Holcombe Brook Coal (South Lancashire)"@en . "HBCO"@en . . . . . . "320.0"^^ . "Holcombe Brook Coal (South Lancashire)"@en . "stable"@en . . .