"Mudstone. Stratified bedrock. Occurs onshore. Deposited during the Anisian Age - to - Ladinian Age (Triassic Period) (246.7-237 Ma BP)."@en . "Byley Mudstone Member"@en . . . "stable"@en . "Top of highest substantial laminated greenish grey and reddish brown bed in this formation; base of Wych Mudstones."@en . . "Byley Mudstone Formation [Obsolete: use BYM]"@en . . . "Byley Mudstone Member"@en . "246.7"^^ . . . . "Keuper Marl, Middle [Obsolete: use BYM, MMG]"@en . "180.90 m in Byley borehole (SJ 76 NW/7)."@en . "237.0"^^ . "Top of Northwich Halite."@en . "BYM"@en . "Alternations of structureless reddish brown mudstone and laminated greenish grey and reddish brown mudstones. NOTE: The contact between the Byley Mudstones and overlying Wych Mudstones is not currently shown on British Geological Survey maps, and they have been mapped as one division."@en .