The BGS Lexicon of Named Rock Units — Result Details

Salop Formation

Computer Code: SAL Preferred Map Code: Sal
Status Code: Full
Age range: Asturian Substage (CAS) — Cisuralian Epoch (PLC)
Lithological Description: Red and red-brown mudstone, and red-brown (mostly sublitharenite) sandstone containing beds of pebbly sandstone and conglomerate itself containing Carboniferous limestone and chert clasts, and thin 'Spirobis' limestone beds and caliche in the lower part of the unit.
Definition of Lower Boundary: Conformable, transitional-gradational boundary taken at the base of the first, at least 1 m thick, red-bed stratum, overlying the grey mudstone-dominated Dark Slade Member of the underlying Halesowen Formation. Where this is also red, the boundary is drawn arbitrarily, above the top of the highest litharenite sandstone.
Definition of Upper Boundary: In the type area at the boundary occurs at the base of the Clent Formation. The boundary is an unconformable or disconformable sharp junction, in the Clent Hills where the Clent Formation is a red-brown breccia; or is a gradational boundary where there is red mudstone-dominated Clent Formation; but is taken at the base of red sandstone with Uriconian volcanic clasts in the Gospel End area of the West Midlands. In Warwickshire, the boundary is conformable below the red-brown mudstone-dominated succession of the Tile Hill Mudstone Formation.
Thickness: From 200 m to 360m thick in Shropshire, and 625 m thick in Warwickshire.
Geographical Limits: Staffordshire, Shropshire and Warwickshire.
Parent Unit: Warwickshire Group (WAWK)
Previous Name(s): Radwood Formation [Obsolete Name And Code: See SAL] (RWD)
Erbistock Formation [Obsolete Name And Code: See SAL and HA] (ERB)
Enville Formation [Obsolete Name And Code: See EN] (EB)
Meriden Formation [Obsolete Name And Code: See SAL] (MRD)
Keele Formation [Obsolete Name And Code: Use ALY] (KE)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Romsley Borehole No.31 (SO97NE/216), from 8.85m at the upper boundary, down to 67.35 m depth, comprising the upper part of the formation. Glover and Powell, 1996. 
Reference Section  BGS Daleswood Farm Borehole (SO97NE/452), from 3.7 m close to the top of the unit, down to 147.4 m at the base of the unit. Glover and Powell, 1996. 
Reference Section  Alveley-1 Borehole (SO78NE/2), from surface to 76.8 m depth. Besly and Cleal, 1997. 
Reference Section  Rough Close Borehole (SP27NE/9), base defined at about 718m depth, and the top at 109m depth, uncored, but has a full suite of geophysical logs available. Uncored borehole, but a full suite of geophysical logs is available; base undefined at c.718m depth; top at 109m depth (Bridge et al., 1998, fig.32). 
Reference Section  Birch Tree Farm Borehole (SP38SW/161) in the lower part of the formation, cored from base at 558 m to 300 m. Bridge et al., 1998, fig.32. 
Type Area  Bowhills and Enville Sheepwalks, near Alveley, from River Severn, north-east to the Bobbington area. 
Reference Section  Penn No.5 Borehole (NCB) (SO89NE/6) [SO 8925 9654] from 562.4m (base) to 202.6m depth (top) (Powell, 1991) 
Reference(s):
Besly, B M and Cleal, C J, 1997. Upper Carboniferous stratigraphy of the West Midlands (UK) revised in the light of borehole geophysical logs and detrital compositional suites. Geological Journal 32, 85 - 118. 
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. 
Powell, J H. 1991. Geology of the Penn District. British Geological Survey Technical Report WA/91/76. 
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:
E169 E184 E138 E153 E154 E167 E182 E183 E108 E109 E121 E122 E123 E152 E168