"BTG"@en . "Mudstone, sandstone and siltstone. Stratified bedrock. Occurs onshore. Deposited during the Early Devonian Epoch (Devonian Period) (419-394.3 Ma BP)."@en . "419.0"^^ . "stable"@en . . "Buttergask Member [Obsolete: use BTG]"@en . . "394.3"^^ . "Buttergask Formation [Obsolete: use BTG]"@en . . . "The top of the Sheriffmuir Sandstone Member, where medium- to coarse-grained sandstones are overlain by fine-grained sandstones and siltstones of the Buttergask Flagstone Member."@en . "Buttergask Flagstone Member"@en . "Grey and brown, fine-grained interbedded sandstones, siltstones and mudstones."@en . "Up to 270 m thick."@en . "The base of the Dunblane Formation, where the medium- to coarse-grained sandstones overlie a fine-grained sandstone and siltstone sequence."@en . . . . . . . "Buttergask Flagstone Member"@en .