The BGS Lexicon of Named Rock Units — Result Details

Pennine Lower Coal Measures Formation
Computer Code: PLCM Preferred Map Code: PLCM
Status Code: Full
Age range: Langsettian Sub-age (CA) — Langsettian Sub-age (CA)
Lithological Description: Interbedded grey mudstone, siltstone and pale grey sandstone, commonly with mudstones containing marine fossils in the lower part, and more numerous and thicker coal seams in the upper part.
Definition of Lower Boundary: At the base of the dark grey, fissile mudstone of the Subcrenatum Marine Band with eponymous fossils, or at the base of the lowest coal of the coal-bearing sequence if this marker cannot be recognised. Typically, the formation rests conformably upon the Rossendale Formation (Millstone Grit Group). However, in north, west and east Cumbria, the Solway Basin (except the Canonbie area), the Stainmore and Northumberland troughs, on the Alston Block and in northeast Northumberland, the formation overlies conformably the repetitive mudstones, siltstones, sandstones, thin limestones and thin coals of the Stainmore Formation (Yoredale Group). In the Canonbie Coalfield, the formation is underlain unconformably by the Alston Formation (Yoredale Group).
Definition of Upper Boundary: At the base of the mudstone of the Vanderbeckei Marine Band with eponymous fossils.
Thickness: Up to 650m thick in the North Staffordshire (Potteries) Coalfield, and 720m thick in Lancashire.
Geographical Limits: Central and northern England, North Wales and the north Isle of Man.
Parent Unit: Pennine Coal Measures Group (PCM)
Previous Name(s): Lower Coal Measures Formation [Obsolete Name And Code: Use PLCM, SWLCM, LCMS] (LCM)
Grey Measures Of Yorkshire And Nottingham [Obsolete Name And Code: See PLCM And PMCM] (GRM)
Lower Coal Measures (-1759)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Base: Natural section in the River Little Don, Langsett [SE 2215 0041] basal Stratotype for the Langsettian Stage with up to 2m section including the Subcrenatum Marine Band. Owens et al., 1985 
Reference Section  Top boundary: Mudstone in the Vanderbeckei Marine Band, Miry Wood, Apedale. To be designated a RIGS site. 
Reference Section  Top part: From 2100 ft (640m) to 1045 ft (318.5m) in constructed stratigraphical section (V5 British Coal, G7 British Geological Survey), Hesketh Back Cut (Crosscut), Chatterley Whitfield Colliery, Stoke-on-Trent. 
Reference Section  Ballavaarkish (Shellag North) Borehole [NX 4625 0070], north Isle of Man includes the Pennine Lower Coal Measures Formation from 120.75m (the top of the cored section) to the base of the Subcrenatum Marine Band at about 136.8m depth. Chadwick et al. 2001 
Reference Section  Base and lower part: From surface down to 1806 ft 10 ins (550.7 m) depth, Ridgeway Borehole (SJ85SE14). 
Type Area  Numerous borehole and shaft section, but few exposures across the North Staffordshire (Potteries) Coalfield, Stoke-on-Trent. Rees and Wilson, 1998 
Reference(s):
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. 
Owens, B, Riley, N J and Calver, M A. 1985. Boundary stratotypes and new stage names for the Lower and Middle Westphalian sequences in Britain. Compte Rendu 10e Congrhs Strat. Giol. Carbonifhre, Madrid, 1983, Vol.4, 461-472. 
Rees, J G and Wilson, A A. 1998. Geology of the country around Stoke-on-Trent. Memoir of the British Geological Survey, Sheet 123 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E100 E108 E110 E111 E112 E123 E124 E125 E139 E014 E141 E015 E152 E153 E154 E155 E166 E167 E168 E169 E018 E019 E020 E022 E023 E024 E026 E028 E031 E032 E050 E051 E052 E059 E062 E068 E069 E070 E075 E076 E077 E078 E084 E085 E086 E087 E009 E097 E098 E099
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