| Computer Code: |
SBNB |
Preferred Map Code: |
SNB |
| Status Code: |
Full |
| Age range: |
Sinemurian Age (JS)
— Sinemurian Age (JS) |
| Lithological Description: |
Grey mudstone beds with numerous ovoid sideritic ironstone nodules 0.05 to 0.1 m across, weathering to reddish brown. Fauna includes gastropods, bivalves (Gryphaea), ammonites and belemnites. |
| Definition of Lower Boundary: |
Change up from mudstone with sparse argillaceous limestone nodules of undifferentiated Charmouth Mudstone Formation into mudstone with ironstone nodules (as described under Lithology); at 181.5 m depth in type section Copper Hill Borehole (SK94SE/56). |
| Definition of Upper Boundary: |
Change up from mudstone with ironstone nodules (as described under Lithology) into mudstone with sparse limestone nodules of undifferentiated Charmouth Mudstone Formation; at c.177.2 m depth in type section Copper Hill Borehole (SK94SE/56). |
| Thickness: |
3 to 5 m; c.4.0 m in type section. |
| Geographical Limits: |
East Midlands: north Leicestershire to Linclonshire. Not recognised in the Charmouth Mudstone Formation of north Lincolnshire, or south Leicestershire, where it passes south into the mudstone-dominated Charmouth Mudstone Formation. |
| Parent Unit: |
Charmouth Mudstone Formation (CHAM)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
BGS Copper Hill Borehole (SK94SE/56). |
| Reference(s): |
| Carney, J N, Ambrose, K and Brandon A. 2002. Geology of the Melton Mowbray district - a brief explanation of the geological map. British Geological Survey Sheet Explanation, Sheet 142 (England and Wales). |
| Berridge, N G, Pattison, J, Samuel, M D A, Brandon, A, Howard, A S, Pharaoh, T C, and Riley, N J. 1999. Geology of the Grantham district. Memoir of the British Geological Survey, sheet 127 (England and Wales). |
| Brandon, A, Sumbler, M G, and Ivimey-Cook, H C. 1990. A revised lithostratigraphy for the Lower and Middle Lias (Lower Jurassic) east of Nottingham, England. Proceedings of the Yorkshire Geological Society, Vol. 48, 121-141. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E127
E126
|
