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): Revidge Grit [Obsolete Name And Code: Use FLB] (RV)
Main Third Grit (-4045)
Gorpley Grit (GGT)
Alternative Name(s): Midgley Grit
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 Section  Fletcher Bank Borehole (SD81NW/3), from 0-65 feet depth below ground level proving the basal part of the unit. 
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