The BGS Lexicon of Named Rock Units — Result Details

Pennine Middle Coal Measures Formation and South Wales Middle Coal Measures Formation (Undifferentiated)

Computer Code: PSMCM Preferred Map Code: notEntered
Status Code: Full
Age range: Duckmantian Substage (CB) — Bolsovian Substage (CC)
Lithological Description: Interbedded grey mudstone, siltstone, pale grey sandstone and commonly coal seams, with a bed of mudstone containing marine fossils at the base, and several such marine fossil-bearing mudstones in the upper half of the unit.
Definition of Lower Boundary: The base of the dark grey, fissile mudstone of the Vanderbeckei Marine Band, with eponymous fauna and/or other marine fossils (see Stubblefield and Trotter, 1957).
Definition of Upper Boundary: The top of the dark grey, fissile mudstone of the Cambriense Marine Band, with eponymous fauna and/or other marine fossils (see Stubblefield and Trotter, 1957). This definition is extended to the Scottish Solway area, which formerly used the top of the Aegiranum (Skelton) Marine Band to define the top of the formation.
Thickness: Up to 600 m thick across the North Staffordshire Coalfield; about 650 m thick in Lancashire; 200 m thick in northwest England and in the northwest of the Canonbie Coalfield. c.120 m on east crop of the South Wales Coalfield [SO 20] to 240 m in the Swansea area [SS 88].
Geographical Limits: The unit is present at crop and in the subsurface over extensive parts of central and northern England, North Wales, the South Wales Coalfield and Pembrokeshire Coalfield, across the Bristol-Somerset coalfields and is present in the subsurface in the Berkshire and Kent coalfields.
Parent Unit: none recorded or not applicable
Previous Name(s): Grey Measures Of Yorkshire And Nottingham [Obsolete Name And Code: See PLCM And PMCM] (GRM)
Middle Coal Measures (-3064)
Alternative Name(s): Pennine Middle Coal Measures Formation
South Wales Middle Coal Measures Formation
Stratotypes:
none recorded or not applicable
Reference(s):
Waters, C N, Waters, R A, Barclay, W J, and Davies, J R. 2009. Lithostratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/09/01. 184pp. 
Stubblefield, C J and Trotter, F M, 1957. Divisions of the Coal Measures on Geological Survey Maps of England and Wales. Bulletin of the Geological Survey of Great Britain, No.13, p.1-5. 
British Geological Survey. 2007. Bedrock Geology UK North. 1:625 000 scale (Keyworth, Nottingham: British Geological Survey). 
Dean, M T, Browne, M A E, Waters, C N and Powell, J H. 2011. A lithostratigraphical framework for the Carboniferous successions of northern Great Britain (onshore). British Geological Survey Research Report, RR/10/007. 165pp. 
British Geological Survey. 2007. Bedrock Geology UK South. 1:625 000 scale (Keyworth, Nottingham: British Geological Survey). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable