"Brathay Formation, Birk Riggs Formation And Wray Castle Formation (Undifferentiated)"@en . . "Mudstone, sandstone and siltstone with subsidiary laminated hemipelagic mudstone and siliciclastic argillaceous rock. Bedrock. Occurs onshore. Formed during the Sheinwoodian Age - to - Gorstian Age (Silurian Period) (432.9-425 Ma BP)."@en . "stable"@en . "425.0"^^ . . . "Brathay Formation, Birk Riggs Formation And Wray Castle Formation (Undifferentiated)"@en . . . "See the Lithology descriptions for the component formations."@en . "BBWC"@en . . "432.9"^^ .