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:
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 Section  ICI Saleway Borehole, near Droitwich, Hereford and Worcester, from 35.66m to 214.27m depth 
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