The BGS Lexicon of Named Rock Units — Result Details

Roaches Grit

Computer Code: ROG Preferred Map Code: notEntered
Status Code: Full
Age range: Marsdenian Substage (CZ) — Marsdenian Substage (CZ)
Lithological Description: Medium-to coarse-grained or fine-grained, feldspathic, massive, rarely cross-bedded sandstone, with sole marks and load casts, and turbiditic mudstone. The sandstone is interpreted to have been deposited in a delta-top setting.
Definition of Lower Boundary: The unit is poorly defined. In the field and in stratigraphic logs, the lower boundary is taken at the base of a sandstone-dominated succession overlying a mudstone interval of Millstone Grit Group that in turn overlies sandstones of either the Five Clouds Sandstone or the Corbar Grit, or mudstone of undifferentiated Millstone Grit Group.
Definition of Upper Boundary: The upper boundary is taken at the base of a mudstone-dominated succession overlying the Roaches Grit, 10 m to 61 m below fissile black mudstone, that includes a Bilinguites superbilinguis Marine Band.
Thickness: From 60 m to-375 m thick.
Geographical Limits: Chinley, Derbyshire (SK 045 825) to Upper Hulme, Staffordshire (SK 01 61) to Rainow, Cheshire (SJ 95 76).
Parent Unit: Marsden Formation (MARSD)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  The Roaches escarpment, in Staffordshire, and Roach End to Hen Cloud, which is a natural cliff section exposing a partial section of the unit (no further details available). Aitkenhead et al., 1985. 
Reference Section  Quarry at Lightwood reservoir near Buxton, Derbyshire, which exposes 12.1 m of coarse-grained, well-bedded sandstone. Stevenson and Gaunt, 1971. 
Reference(s):
Smith, E G, Rhys, G H and Eden, R A. 1967. Geology of the country around Chesterfield, Matlock, and Mansfield. Memoir of the Geological Survey of Great Britain. England and Wales Sheet 112. 
Jones, C M, 1980. Deltaic sedimentation in the Roaches Grit and associated sediments (Namurian R2b) in the south-west Pennines. Proceedings of the Yorkshire Geological Society Vol.43, Pt.1, 39-67. 
Stevenson, I P and Gaunt, G D, 1971. Geology of the country around Chapel-en-le-Frith. Memoir of the Geological Survey of Great Britain, England and Wales, Sheet 99. 
Aitkenhead, N, Chisholm, J I and Stevenson, I P. 1985. Geology of the country around Buxton, Leek and Bakewell. Memoir of the British Geological Survey, England and Wales Sheet 111. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E099 E098 E110 E111