The BGS Lexicon of Named Rock Units — Result Details
Wych Mudstone Member
Computer Code: | WYM | Preferred Map Code: | WyM |
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Status Code: | Full | ||
Age range: | Ladinian Age (TD) — Ladinian Age (TD) | ||
Lithological Description: | Structureless reddish brown mudstones with anhydrite/gypsum nodules mostly in uppermost two thirds of Member. | ||
Definition of Lower Boundary: | Top of highest greenish grey and reddish brown laminated unit of the Byley Mudstones. | ||
Definition of Upper Boundary: | Base of Wilkesley Halite. Some thin halite bands in Palmer Mann No.12 Borehole have been included in the Wych Mudstones. | ||
Thickness: | 186.44 m in Wilkesley Borehole (611' 8"). | ||
Geographical Limits: | Cheshire Basin. | ||
Parent Unit: | Sidmouth Mudstone Formation (SIM) | ||
Previous Name(s): | Middle Keuper Marl [Obsolete Name and Code: Use WYM]
(-4199)
Wych Mudstone Formation [Obsolete Name and Code: Use WYM] (-1289) Mercia Mudstone Group (Middle Division) [Obsolete Name and Code: Use WYM] (-1288) |
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Alternative Name(s): | none recorded or not applicable | ||
Stratotypes: | |||
Partial Type Section | (Intermittent exposure). Sections in Wych Brook (lower half of formation, with gaps). Best exposure in 3.1 m mudstone at SJ 4907 4507. | ||
Reference Section | Core at BGS Keyworth from 50 - 156 m depth in Crewe Heat Flow Borehole (BGS) (SJ65SE/6), 5 - 156 m depth. | ||
Type Section | BGS Wilkesley Borehole 752.34 - 938.78 m. (2468' 4" - 3080' 2") (SJ64SW/7). | ||
Reference(s): | |||
Wilson, A A. 1993. The Mercia Mudstone Group (Trias) of the Cheshire Basin. Proceedings of the Yorkshire Geological Society, Vol.49, 171-188. | |||
Howard, A S, Warrington, G, Ambrose, K, and Rees, J G. 2008. A formational framework for the Mercia Mudstone Group (Triassic) of England and Wales. British Geological Survey Research Report, RR/08/04. | |||
1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
E123 |