. "Sandstones, mudstones and coals of the defining formations (listed here in alphabetical order): Beatrice Formation (including the Carr and Louise members); Brora Coal Formation; Hugin Formation; Pentland Formation (including the Rattray Volcanics, Ron Volcanics and Stroma members)."@en . "West Sole Group"@en . "Fladen Group"@en . . "Mudstone and sandstone with subsidiary agglomerate, basalt, coal and tuff. Stratified bedrock. Occurs offshore. Deposited during the Aalenian Age - to - Oxfordian Age (Jurassic Period) (174.7-154.8 Ma BP)."@en . . "The upper group boundary is variable in the northern North Sea, but is normally marked by the upward transition from sandstones or interbedded sandstones, siltstone and coal to mudstones and siltstones of the overlying Heather Formation (Humber Group). The top of the Fladen Group is generally the top of the Hugin Formation, but in the Central Graben, either the Pentland Formation or Beatrice formation underlies the Heather Formation."@en . "The lower group boundary is defined by the base of the Pentland Formation, which unconformably overlies Permian, Triassic and Lower Jurassic sediments. Where it overlies Permian sediments, the base is marked by a downward change from coal-bearing sediments and/or volcanics to evaporite-bearing sediments; where it overlies the Triassic, the boundary is marked by a transition from grey coal-bearing sediments and/or volcanics to brick-red siltstones and sandstones; where it overlies Lower Jurassic strata, the boundary is marked by a downward transition from interbedded sandstones, siltstones and coals to predominantly grey siltstones with minor sandstones."@en . "FLDN"@en . "Fladen Group"@en . . . . . . . "154.8"^^ . "174.7"^^ . "stable"@en . .