|Coal Measures Group [Obsolete Except In Northern Ireland: Use PCM, SWCM, CMSC]
||Preferred Map Code:
||Westphalian Age (CW)
— Westphalian Age (CW)
|| Alternation of sandstone, grey siltstone and grey mudstone, with frequent coal seams and seatearth horizons. NOTE: Definitions for the base of the Coal Measures, and the bases of the Middle and Upper divisions, are those of Stubblefield and Trotter (1957), but the top of the Coal Measures in the Pennine Basin is newly defined on a purely lithostratigraphical basis, (Powell et al., 1999). In areas such as South Wales, where no significant Carboniferous red-beds overlie the coal-bearing measures, the top of the Coal Measures may be defined differently.
|Definition of Lower Boundary:
|| Base of Gastrioceras subcrenatum Marine Band (=Subcrenatum Marine Band) or at base of coal-bearing sequence if this marker band cannot be identified.
|Definition of Upper Boundary:
|| Base of lowest conformably overlying red-bed formation - Etruria Marl or lateral equivalent.
|| Up to 1600m in the Potteries Syncline; to c.1900m in Lancashire.
|| Britain, except Devon and Cornwall, and parts of Ireland for the Group; England and Wales for divisions LCM, MCM and UCM.
Not Applicable (-)
|| Productive Coal Measures
none recorded or not applicable
||For top and upper part. Wolstanton Colliery No.3 Shaft (SJ84NE/29) from 1142ft 7ins to base of shaft.
||For boundary between Lower and Middle Coal Measures. Mirywood: Locality C on map SJ84NW: to become a designated RIGS; base of Vanderbeckei Marine Band is boundary.
||For base and lower part. Ridgeway Borehole (SJ85SE/14) from surface to 1806ft 10ins.
||For boundary between Middle and Upper Coal Measures. Parkhouse Colliery No.1 Underground Borehole (SJ85SW/19): top of Cambriense Marine Band, at 529ft depth in bore, is boundary.
||Pennine coalfields. Full development in Potteries Syncline, with numerous borehole and shaft sections but few good exposures. (Rees and Wilson, 1998).
|Whitehead, T H and Pocock, R W, 1947. Dudley and Bridgnorth. Memoir of the Geological Survey of Great Britain.
|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.
|Powell, J H, Chisholm, J I, Bridge D M, Rees, J G, Glover, B W and Besly, B M, 1999. Stratigraphical framework for Westphalian to Early Permian red-bed successions of the Pennine Basin. British Geological Survey Technical Report, WA/99/101.
|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).
|Besley B M, 1988. Palaeogeographic implications of late Westphalian to early Permian red-beds, central England. "In" Sedimentation in a synorogenic basin complex. Besley B M and Kelling, G, editors.
|1:50K maps on which the lithostratigraphical unit is found, and map code used:
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