||Preferred Map Code:
||Langsettian Substage (CA)
— Langsettian Substage (CA)
|| 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.
|| Up to 650m thick in the North Staffordshire (Potteries) Coalfield, and 720m thick in Lancashire.
|| Central and northern England, North Wales and the north Isle of Man.
Pennine Coal Measures Group (PCM)
|| LOWER COAL MEASURES
none recorded or not applicable
||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.
|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.
||Top boundary: Mudstone in the Vanderbeckei Marine Band, Miry Wood, Apedale. To be designated a RIGS site.
||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.
||Base and lower part: From surface down to 1806 ft 10 ins (550.7 m) depth, Ridgeway Borehole (SJ85SE14).
||Numerous borehole and shaft section, but few exposures across the North Staffordshire (Potteries) Coalfield, Stoke-on-Trent.
|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).
|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.
|1:50K maps on which the lithostratigraphical unit is found, and map code used: