The BGS Lexicon of Named Rock Units — Result Details

Clent Formation

Computer Code: CLT Preferred Map Code: Cle
Status Code: Full
Age range: Cisuralian Epoch (PLC) — Cisuralian Epoch (PLC)
Lithological Description: Breccia, sub-angular, with red-brown mudstone matrix, clasts predominantly 'Precambrian-Uriconian' volcanic rocks and subordinate Lower Palaeozoic rocks. Red pebbly mudstone and sandstone in Wolverhampton area.
Definition of Lower Boundary: Unconformable/disconformable boundary between underlying mudstone/sandstone of Salop Formation (Enville Member) and coarse breccia above (in type area); gradational boundary in Wolverhampton area.
Definition of Upper Boundary: Generally, modern erosion surface in type area, locally overlain unconformably by Kidderminster Formation (Triassic).
Thickness: c.138m in Clent Hills, c.240m in Wolverhampton/Baggeridge area to north.
Geographical Limits: West Midlands; South Staffordshire and Birmingham areas.
Parent Unit: Warwickshire Group (WAWK)
Previous Name(s): Breccia Group (-3309)
Clent Group (-3310)
Clent Hills Breccia (-137)
Nechells Breccia [Obsolete Name And Code: Use CLT] (NCHB)
Clent Breccias [Obsolete Name And Code: See CLT] (CLE)
Trappoid Breccia (-791)
Alternative Name(s): none recorded or not applicable
Type Area  Clent Hills, near Hagley; from Park Visitors Car Park [SO 935 807] to summit of Clent Hills. 
Reference Section  (c) (Mudstone dominated strata), Penn Common, Penn Brook (stream section). 
Reference Section  (a) Breccia lithofacies; Romsley Borehole No.31 (SO 97 NE/216); lower boundary at 8.85m depth (Glover and Powell, 1996). 
Reference Section  (b) Mudstone/sandstone lithofacies; Penn No. 5 Borehole (SO 89 NE/6); from 83m depth (base) to 20m depth (top) (Glover and Powell, 1996). 
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. 
Old R A, Hamblin, R J O, Ambrose, K, and Warrington G. 1991. Geology of the country around Redditch. Memoir of the British Geological Survey, Sheet 183 (England and Wales). 
Wills, L J. 1956. Concealed Coalfields. (Glasgow & London: Blackie). 
Glover, B M and Powell, J H, 1996. Interaction of climate and tectonics upon alluvial architecture: Late Carboniferous-Early Permian sequences at the southern margin of the Pennine Basin, UK. Palaeogeography, Palaeoclimatology and Palaeoecology, Vol. 121, 13 - 34. 
Whitehead, T H and Eastwood, T, 1927. The geology of the southern part of the South Staffordshire Coalfield. Memoir of the Geological Survey of Great Britain. 
Boulton, W S, 1924. On a recently discovered breccia bed underlying Nechells (Birmingham) and its relation to the red rocks of the district. Quarterly Journal of the Geological Society, Vol.80, 343-373. 
Glover, B W, 1991. Geology of the Wombourne District. British Geological Survey Technical Report WA/90/76. 
Powell, J H, 1991. Geology of the Lye District. British Geological Survey Technical Report. WA/91/59 
Powell, J H, Glover, B W and Waters, C N, 1992. A Geological background for planning and development in the `Black Country'. British Geological Survey Technical Report WA/92/33. 
King, W W, 1923. The unconformity below the trappoid (Permian?) breccias. Proceedings of the Worcestershire Naturalists' Club, Vol.8, p.3-8. 
Eastwood, T, Whitehead, T H, and Robertson, T. 1925. The geology of the country around Birmingham. Memoir of the British Geological Survey of Great Britain. 
King, W W, 1893. Clent Hills Breccia. Midland Naturalist, Vol.16, 25-37. 
Peace, G R and Besly, B M. 1997. End-Carboniferous fold-thrust structures, Oxfordshire, UK: implications for the structural evolution of the late Variscan foreland of south-central England. Journal of the Geological Society, London, Vol. 154, 225 - 237. 
Wills, L J and Shotton, W. 1938. A quartzite breccia at the base of the Trias in a trench near Tessall Lane. Proceedings of the Birmingham Natural History and Philosophical Society, Vol. 16, 181 - 183. 
Smith, D B and 4 others, 1974. A correlation of Permian rocks in the British Isles. Journal of the Geological Society of London, Vol.130, 1-45. 
Powell, J H, Chisholm, JI, 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/99/10. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E167 E183 E168