The BGS Lexicon of Named Rock Units — Result Details
Fletcher Bank Grit
| Computer Code: | FLB | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Marsdenian Substage (CZ) — Marsdenian Substage (CZ) | ||
| Lithological Description: | 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. | ||
| Definition of Lower Boundary: | 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. | ||
| Definition of Upper Boundary: | 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. | ||
| Thickness: | 110.97 m is the maximum measured thickness [SD81SW/3], allthough the bottom was not proved. | ||
| Geographical Limits: | Southern Pennines, Manchester [SJ 8398] to Clitheroe [SD 7441], west of the Pennine Anticline. Appears with several codesused on the same mapsheet as: E68, GG RV; E75, FB Rv; E76, Rv FB GG, E85, GG. | ||
| Parent Unit: | Marsden Formation (MARSD) | ||
| Previous Name(s): | Gorpley Grit
(GGT)
Main Third Grit [Obsolete Name and Code: Use FLB] (-4045) Revidge Grit [Obsolete Name And Code: Use FLB] (RV) Gorpley Grit (GGT) |
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| Alternative Name(s): | Midgley Grit |
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| Stratotypes: | |||
| Reference Section | Fletcher Bank Borehole (SD81NW/3), from 0-65 feet depth below ground level proving the basal part of the unit. | ||
| Type Section | Gin Hall Reservoir Borehole [SD81SW/3], from 551 feet to 906 feet below ground level (at TD). Top of the unit proved; base of the unit not proved. Wright et al., 1927. | ||
| Reference(s): | |||
| Wright, W B, Sherlock, R L, Wray, D A, Lloyd, W and Tonks, L H, 1927. The Geology of the Rossendale Anticline. Memoir of the Geological Survey, England. England and Wales Sheet 76. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E084 E075 E068 E076 E085 | |||