The BGS Lexicon of Named Rock Units — Result Details

Etruria Formation

Computer Code: ETM Preferred Map Code: Et
Status Code: Full
Age range: Westphalian Stage (CW) — Westphalian Stage (CW)
Lithological Description: Red, purple, brown, ochreous, green, grey and commonly mottled mudstone, with lenticular sandstones and conglomerates referred to as 'espleys'. Common pedogenic horizons, but coal seams are rare. Subordinate, lenticular sandstones and conglomerates commonly consist mostly of volcanic and lithic clasts. Intrusions of dolerite sills and dykes and extrusion of a small volume of volcaniclastic rocks are present in south Staffordshire and south Nottinghamshire.
Definition of Lower Boundary: Passage by alternation from grey mudstones of the Pennine Coal Measures Group to red, purple mudstone of the Etruria Formation. Locally, in Shropshire, Warwickshire and Lincolnshire, the lower boundary is an unconformity (Symon Unconformity).
Definition of Upper Boundary: Overlain conformably by predominantly grey sandstone and mudstone strata of the Halesowen Formation, although locally, in South Staffordshire the upper boundary is an unconformity.
Thickness: Up to about 300 m thick in the type area.
Geographical Limits: English Midlands, Lancashire, Yorkshire and North Wales.
Parent Unit: Warwickshire Group (WAWK)
Previous Name(s): Ardwick Marl [Obsolete Name And Code: See ETM] (AM)
Kinlet Formation [Obsolete Name And Code: See ETM] (KTB)
Buckley Fireclay Formation [Obsolete Name And Code: Use ETM] (BFC)
Ruabon Marl Formation [Obsolete Name And Code: See ETM] (RM)
Hadley Formation [Obsolete Name And Code: See ETM] (HD)
Etruria Marl Formation (-2791)
Old Hill Marl (-2793)
Etruria Marl (-1532)
Ardwick Marl(s) (-3391)
Etruria Marl Series (-3392)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Potteries Syncline: Borehole sections and some quarries, including the original type locality at Etruria. Gibson, 1899, p.125 
Reference Section  Barker's Wood Borehole (SJ84NW/68), from 498 ft to 1515 ft 6 in (151.79 to 461.93 m) depth. 
Reference Section  Base: Wolstanton Colliery No 3 Shaft (SJ84NE/29), at 1142 ft 7 in (348.26 m) depth. 
Reference Section  Whole formation: Sidway Mill Borehole (SJ73NE/3), from the base at 3972 ft 7 in (1210.84 m) depth, to the top at 2556ft (779.07 m) depth. 
Reference(s):
Gibson, W, 1899. Summary of Progress of the Geological Survey of Great Britain for 1898, p.122-129. 
Waters, C N, Waters, R A, Barclay, W J, and Davies, J R. 2009. Lithostratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/09/01. 184pp. 
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:
E084 E085 E097 E098 E108 E121 E153 E155 E182 E123 E167 E168 E169 E201 E137 E154