"Brithdir Rider Coal (South Wales)"@en . "Brithdir Rider Coal (South Wales)"@en . . . . . . "Coal."@en . "BDRR"@en . "Coal. Stratified bedrock. Occurs onshore. Deposited during the Bolsovian Substage (Carboniferous Period) (314.75-310 Ma BP)."@en . "314.75"^^ . "stable"@en . . . "310.0"^^ . .