The BGS Lexicon of Named Rock Units — Result Details
Brooks Mill Mudstone Formation [Obsolete: use BCMU]
| Computer Code: | BMI | Preferred Map Code: | BMi |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Carnian Age (TC) — Norian Age (TN) | ||
| Lithological Description: | [Obsolete: use BCMU] Structureless reddish brown and chocolate coloured mudstones with anhydrite/gypsum nodules and bands. NOTE: The upper 20m of the formation includes bands of structureless greenish grey mudstone. Thin bands of sandstone occur 22 to 34m above the base of the formation. | ||
| Definition of Lower Boundary: | Top of highest halite member of the Wilkesley Halite. | ||
| Definition of Upper Boundary: | Base of persistently greenish grey mudstones of Blue Anchor Formation. | ||
| Thickness: | 529' 3" (161.32m) in Wilkesley Borehole. | ||
| Geographical Limits: | Cheshire Basin. | ||
| Parent Unit: | none recorded or not applicable | ||
| Previous Name(s): | Keuper Marl, Upper [Obsolete Name and Code: Use BMI]
(-1999)
Mercia Mudstone Group (Upper Division) [Obsolete Name and Code: Use BMI] (-3861) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Partial Type Section | Reddish-brown structureless mudstone 1.50m. | ||
| Partial Type Section | Reddish-brown, poorly laminated mudstone 0.9m. | ||
| Type Section | Wilkesley Borehole (British Geological Survey) 186.51-347.83m depth. (611' 11" to 1141'2") (SJ64SW/7) | ||
| Reference Section | British Gypsum boreholes AU 15 (SJ64SE/10)(24.60-100.30m) and AU 17 (SJ63NE/21)(44.40-64.10, 101.50-138.60m). Cores held at British Geological Survey, Keyworth. | ||
| Partial Type Section | Exposures on south bank of River Weaver. 300m west-south-west of Brooks Mill, 120m north-west of Brooks Mill. | ||
| 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 | |||