The BGS Lexicon of Named Rock Units — Result Details

Middle Grit [Obsolete Name And Code: Use MARSD]

Computer Code: MGT Preferred Map Code: notEntered
Status Code: Index Level
Age range: Marsdenian Substage (CZ) — Marsdenian Substage (CZ)
Lithological Description: Sandstone overlain by fireclays or ganisters. Coal seams are locally conspicuous and marine bands are well developed. Shale and gritstone also occur.
Definition of Lower Boundary: Drawn at base of marine band containing Bilinguites gracilis where it rests conformably on grits of Kinderscoutian age.
Definition of Upper Boundary: Drawn at conformable upward passage from a marine band containing Gastrioceras Cancellatum to shales of the Rough Rock Group.
Thickness: Up to approximately 360 metres.
Geographical Limits: North England:- Yorkshire, Lancashire, Derbyshire, Staffordshire.
Parent Unit: Millstone Grit Group [See Also MIGR] (MG)
Previous Name(s): Middle Grit Group (-2310)
Middle Grits (-1694)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  North of England. (The grid reference SJ 33 000, 55 000, covers the National Grid areas SD, SE, SJ, SK). 
Reference(s):
Green, A H and others, 1878. Yorkshire Coalfield. Memoirs of the Geological Survey of Great Britain, p.27-33. 
Wray, D A et al, 1930. Geology of the country around Huddersfield and Halifax. Memoir of the Geological Survey of Great Britain. 
Hudson, R G S and Dunnington, H V, 1939. A boring in the Lower Coal Measures and Millstone Grit at Bradford. Proceedings of the Yorkshire Geological Society, Vol.24, p.132. 
Green, A H and others, 1866. One-inch Old Series Sheet 81 NE. Geological Survey of Great Britain. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable