The BGS Lexicon of Named Rock Units — Result Details

Sherwood Sandstone Group

Computer Code: SSG Preferred Map Code: SSG
Status Code: Full
Age range: Induan Age (TI) — Anisian Age (TA)
Lithological Description: Sandstone, red, yellow and brown, part pebbly; conglomeratic in lower part; pebbles generally extraformational quartz and quartzite, with some intraformational clasts; subordinate red mudstone and siltstone.
Definition of Lower Boundary: Disconformable on the Lenton Sandstone Formation in the eponymous area and on the Kinnerton Sandstone Formation in Cheshire. Unconformable on the Aylesbeare Mudstone Group in east Devon, the Bridgnorth Sandstone Formation in the West Midlands, the Cumbrian Coast Group in Lancashire and Cumbria, and the Zechstein Group in north Nottinghamshire, Yorkshire and Durham. In other areas it rests unconformably on rocks ranging from Precambrian to Carboniferous in age.
Definition of Upper Boundary: Gradational into the Tarporley Siltstone Formation of the MMG where mudstone/siltstone becomes dominant over sandstone. In the Bristol area it is taken at the upward change to red sandstones of the Redcliffe Sandstone Member of the MMG (Howard et al., 2008). In the East Midlands the boundary with the Tarporley Siltstone Formation is an unconformity.
Thickness: Variable, maximum >1500 m.
Geographical Limits: British Isles.
Parent Unit: New Red Sandstone Supergroup (NRS)
Previous Name(s): Keuper Series (-2942)
Bunter Sandstone (-1199)
Keuper Marl And Sandstone [Obsolete Name And Code: Use MMG And SSG] (KMS)
Keuper "Series" [Obsolete Name And Code: Use SSG And MMG] (KSR)
Keuper Series, Lower [Obsolete Name And Code: Use SSG or MMG] (LKSR)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Sherwood Forest, Nottinghamshire. 
Reference(s):
Ambrose, K, Hough, E, Smith, N J P and Warrington, G. 2014. Lithostratigraphy of the Sherwood Sandstone Group of England, Wales and south-west Scotland. British Geological Survey Research Report, RR/14/01. 
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. 
Warrington, G, Audley-Charles, M G, Elliott, R E, Evans, W B, Ivimey-Cook, H C, Kent, P E, Robinson, P L, Shotton, F W and Taylor, F M. 1980. A correlation of the Triassic rocks in the British Isles. Special Report of the Geological Society of London, No.13. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E326 E340 E341 E342 E343 N28 E084 E140 E075 E111 E124 E059 E067 E062 E043 N35 E055 E065 E072 E080 E081 E089 E090 E091 E058 E018 E027 E103 E115 E127 E128 E158 S006 E172 E078 E201 E070 E142 E048 E236