. . "BSF"@en . "Mudstone, bedding-fissile, medium-dark grey, variously bioturbated, graptolitic. Sparse thin argillaceous limestone layers with shelly faunas."@en . "Mudstone with subsidiary calcilutite. Stratified bedrock. Occurs onshore. Deposited during the Sheinwoodian Age (Silurian Period) (432.9-430.6 Ma BP)."@en . "Not seen in type area but presumed to rest conformably on Llandovery Purple Shales."@en . "Coalbrookdale Formation"@en . "Bromleysmill Shales Formation [Obsolete: use BSF]"@en . . "Bromleysmill Shale Formation"@en . . . . . "stable"@en . . "432.9"^^ . "Overlain conformably (by rapid passage) by Aston Mudstone Formation. Unnamed dingle (SO 3038 9094)."@en . "May be 500m"@en . "Bromleysmill Shale Formation"@en . . "430.6"^^ .