. "The lower boundary is taken in the Fletcher Bank Borehole at the base of a sandstone dominated sequence overlying a mudstone-dominated succession of the Millstone Grit Group."@en . "Midgley Grit"@en . "Revidge Grit [Obsolete: use FLB]"@en . "stable"@en . "Fletcher Bank Grit"@en . . "321.5"^^ . "Sandstone and pebbly sandstone, coarse-grained with angular grains, with quartz and quartzite pebbles, massive and current-bedded, and subordinate beds of mudstone and coal."@en . "Main Third Grit [Obsolete: use FLB]"@en . . . "FLB"@en . . . "The upper boundary is taken at the base of a mudstone-dominated succession overlying sandstones of the Fletcher Bank Grit; often coincident with the base of an unnamed coal."@en . "Fletcher Bank Grit"@en . . "320.0"^^ . "Sandstone with subsidiary mudstone and pebbly (gravelly) sandstone. Stratified bedrock. Occurs onshore. Deposited during the Marsdenian Substage (Carboniferous Period) (321.5-320 Ma BP)."@en . . . "110.97 m is the maximum measured thickness [SD81SW/3], allthough the bottom was not proved."@en . . .