The BGS Lexicon of Named Rock Units — Result Details

Hopwas Breccia Formation

Computer Code: HPBR Preferred Map Code: HpBr
Status Code: Full
Age range: Cisuralian Epoch (PLC) — Early Triassic Epoch (TE)
Lithological Description: A coarse breccia composed of locally derived material and up to 10% Carboniferous limestone clasts, interbedded with sandstones and subordinate mudstone beds.
Definition of Lower Boundary: Unconformable on Carboniferous and older rocks and also on the Permian Clent and Nechells breccias, which contain a greater variety of extrabasinal clasts (Smith and others, 1974).
Definition of Upper Boundary: Overlain by red sandstones of the Polesworth Formation.
Thickness: Variable, but thicknesses of 30m are recorded (Smith and others, 1974).
Geographical Limits: South Staffordshire, Warwickshire and Leicestershire coalfields area (Hains and Horton, 1969).
Parent Unit: Sherwood Sandstone Group (SSG)
Previous Name(s): Barr Beacon Beds [Obsolete Name And Code: Use HPBR] (ARBC)
Moira Breccia [Obsolete Name And Code: Use MOI] (MOB)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Near village of Hopwas, Leicestershire. Outcrop of breccias composed of locally derived material, described originally by Barrow and others, 1919. 
Reference(s):
Worssam, B C and Old, R A, 1988. Geology of the country around Coalville. Memoir of the British Geological Survey, Sheet 155 (England and Wales) 
Barrow, G, Gibson, W, Cantrill, T C, Dixon, E E L and Cunningham, C H, 1919. The geology of the country around Lichfield. Memoir of the Geological Survey of Great Britain. 
Smith, D B, Brunstrom, R G W, Manning, D I, Simpson, S and Shotton, F W. 1974. A correlation of Permian rocks in the British Isles. Geological Society of London Special Report No. 5. 
Hains, B A and Horton, A.1969. British Regional Geology: Central England. 3rd edition. (London: HMSO). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E155 E154