The BGS Lexicon of Named Rock Units — Result Details
Bollin Mudstone Member
Computer Code: | BOM | Preferred Map Code: | BoM |
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Status Code: | Full | ||
Age range: | Anisian Age (TA) — Anisian Age (TA) | ||
Lithological Description: | The upper part is a dominantly laminated reddish-brown and greenish-grey mudstone with siltstones. The lower part is a structureless and laminated, dominantly reddish-brown mudstone. Within the lower part of the member, a unit termed the 'Lower Keuper Sandstone' has been recognised in the Stockport area. This unit closely resembles the Tarporley Siltstone Formation of adjacent areas. | ||
Definition of Lower Boundary: | Top of Tarporley Siltstone Formation. | ||
Definition of Upper Boundary: | Base of Northwich Halite Member. | ||
Thickness: | 1188 ft 6 ins in the Wilkesley Borehole (British Geological Survey; SJ64SW/7) (362.25 m). | ||
Geographical Limits: | Cheshire Basin. | ||
Parent Unit: | Sidmouth Mudstone Formation (SIM) | ||
Previous Name(s): | Bollin Mudstone Formation
(-74)
Keuper Marl, Lower [Obsolete Name and Code: Use MMG, SIM] (LKM) Mercia Mudstone Group (Lower Division) [Obsolete Name and Code: Use BOM] (-3862) |
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Alternative Name(s): | none recorded or not applicable | ||
Stratotypes: | |||
Partial Type Section | Exposures on banks of River Bollin and its tributaries. | ||
Type Section | Wilkesley Borehole (British Geological Survey) 4166 ft 8 in to 5355 ft 2 in. (SJ64SW/7). | ||
Reference Section | Exposures on banks of Wych Brook and its tributaries. | ||
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 |