The BGS Lexicon of Named Rock Units — Result Details

Somerset Halite Member

Computer Code: SMHF Preferred Map Code: notEntered
Status Code: Full
Age range: Carnian Age (TC) — Carnian Age (TC)
Lithological Description: Mudstone, reddish brown, with abundant beds and veins of halite, and common beds of brecciated mudstone, formed by salt dissolution.
Definition of Lower Boundary: Conformable, at gradational upward transition from reddish brown mudstone (Sidmouth Mudstone Formation, undivided) to mudstone with abundant halite of the Somerset Halite Member.
Definition of Upper Boundary: Conformable, at gradational upward transition from mudstone with abundant halite of the Somerset Halite Member to the reddish brown mudstone of the Branscombe Mudstone Formation.
Thickness: 154m at type section
Geographical Limits: Subsurface, north Somerset, not present at outcrop. Probably equavalent to thick halites in the upper part of the Sidmouth Mudstone Formation in Dorset (Gallois, 2001) and offshore below the English Channel (Hamblin et al. (1992).
Parent Unit: Sidmouth Mudstone Formation (SIM)
Previous Name(s): Somerset Halite Formation (-2434)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Burton Row Borehole (ST35SW/3), Brent Knoll, north Somerset, full sequence proved between 643m and 797m depth. Curated core held at the National Geosciences Records Centre, BGS Keyworth. Whittaker, 1972. 
Reference(s):
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. 
Gallois, R W. 2001. The lithostratigraphy of the Mercia Mudstone Group (mid to late Triassic) of the south Devon coast. Geoscience in south-west England, Vol.10, 195-204 
Whittaker, A. 1972. The Somerset Saltfield. Nature, London. Vol.238, 265-266. 
Hamblin, R J O, Crosby, A, Balson, P S, Jones, S M, Chadwick, R A, Penn, I E, and Arthur, M J. 1992. The geology of the English Channel. British Geological Survey United Kingdom Offshore Regional Report. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable