The BGS Lexicon of Named Rock Units — Result Details

Twyning Mudstone Formation [Obsolete Name And Code: Use BCMU]

Computer Code: TWM Preferred Map Code: TwM
Status Code: Index Level
Age range: Norian Age (TN) — Norian Age (TN)
Lithological Description: Mainly structureless red-brown silty mudstones and siltstones with common gypsum/anhydrite; minor green mudstones and siltstones and laminated beds.
Definition of Lower Boundary: Placed at the base of red, structureless mudstones where they rest on green beds of the underlying Arden Sandstone Formation; boundary is sharp or a rapid transition.
Definition of Upper Boundary: Placed at top of red mudstones where they are overlain by the green beds of the Blue Anchor Formation. Boundary is sharp or rapidly transitional.
Thickness: 169.01m in type section; 15-20m in eastern Warwickshire.
Geographical Limits: Worcester Basin to Warwickshire.
Parent Unit: Mercia Mudstone Group (MMG)
Previous Name(s): Twyning Formation (-2507)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  ICI Saleway Borehole, near Droitwich, Hereford and Worcester, from 35.66m to 214.27m depth 
Type Section  BGS Twyning Borehole, 560m at 040 from Twyning Church, Twyning, near Tewkesbury, Gloucestershire; from 141.5-310.51m depth. (Barclay, W J and others. 1997; Worssam and others, 1989). 
Reference Section  BGS Stowell Park Borehole, near Northleach, Gloucestershire, from 2112' 9" to 2512' 1" depth. (Green and Melville, 1956). 
Reference(s):
Worssam, B C, Ellison, R A and Moorlock, B S P. 1989. Geology of the country around Tewkesbury. Memoir of the British Geological Survey, Sheet 216 (England and Wales). 
Green, G W and Melville, R V. 1956. The stratigraphy of the Stowell Park Borehole (1949-1951). Bulletin of the Geological Survey of Great Britain, No.11, p.1-66. 
Barclay, W J, Ambrose K, Chadwick, R A and Pharaoh, T C. 1997. Geology of the country around Worcester. Memoir of the British Geological Survey, Sheet 199 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E199