. . "The formation is over 200 m thick throughout most of the UK sector and exceeds 300 m in quadrants 42, 43 and 44, and adjacent parts of quadrants 41, 47, 48 and 49; it is over 400 m thick on the northwest side of the Cleaver Bank High (Cameron, 1993)."@en . "246.7"^^ . . "The top of the Bunter Shale Formation is defined by a downward change from the dominantly arenaceous sequence of the Bunter Sandstone Formation to a predominantly argillaceous succession. The boundary is usually clear and is marked by a downward increase in gamma-ray values, but may be less distinct towards the London-Brabant Platform and the eastern UK onshore area where the Amethyst Member, which includes sandstones up to 10 m thick, forms the upper part of the Bunter Shale Formation."@en . . . . "BTSH"@en . "stable"@en . "The base of the Bunter Shale Formation is defined by a downward change from red-brown, silty, dolomitic or anhydritic mudstones, interbedded with siltstones and some fine sandstones, to anhydrites and halites or, in rare instances (e.g. 54/11-1), carbonates of the Zechstein Group. This boundary corresponds to an abrupt downhole decrease in gamma-ray values and a marked increase in velocity. Throughout most of the UK sector the Bunter Shale Formation overlies the Grenzanhydrit of the Z5 cycle. In the southeast of the sector, however, the Bunter Shale Formation may be interpreted as resting upon Zechstein carbonates (e.g. 54/11-1), indicating the presence of an unconformity with overstep."@en . "Mudstone and siltstone. Stratified bedrock. Occurs offshore. Deposited during the Early Triassic Epoch (Triassic Period) (251.9-246.7 Ma BP)."@en . . "251.9"^^ . . . "Bunter Shale Formation"@en . . "The Bunter Shale Formation consists predominantly of red, red-brown, and some grey mudstones and shales. In basin margin areas, sandstones interbedded with silty mudstones in the upper part of the formation form the Amethyst Member; this passes distally into the Rogenstein Member which comprises mudstones with siltstone and some dolomite interbeds and traces of anhydrite, and is characterized by the presence of calcareous oolitic beds (rogenstein). The lowest beds of the formation comprise redbrown, silty, dolomitic or anhydritic, mudstones interbedded with siltstones and some fine sandstones, and constitute the Brockelschiefer Member which includes the Hewett Sandstone."@en . "Bunter Shale Formation"@en . .