"320.0"^^ . "stable"@en . . . "321.5"^^ . "Siltstone with subsidiary sandstone. Stratified bedrock. Occurs onshore. Deposited during the Marsdenian Substage (Carboniferous Period) (321.5-320 Ma BP)."@en . . . "Keighley Bluestone"@en . "Siltstone with subsidiary sandstone."@en . . "KBST"@en . . . "Keighley Bluestone"@en . .