The BGS Lexicon of Named Rock Units — Result Details

Stoer Group

Computer Code: TA Preferred Map Code: notEntered
Status Code: Full
Age range: Stenian Period (AI) — Stenian Period (AI)
Lithological Description: Conglomerate near base; red coarse, cross-bedded sandstone, locally with mudstone beds; green sandstone with mafic fragments and lapilli; thick bedded sandstone; massive mudstone with thin limestone beds.
Definition of Lower Boundary: Drawn at base of massive breccias of the Stoer Group where it rests unconformably on Lewisian Gneiss Complex.
Definition of Upper Boundary: Not exposed; the highest formation is eroded. Unconformably overlain by the Torridon Group via an angular unconformity.
Thickness: 700 - 1500 m (minimum).
Geographical Limits: Northwest Highlands: Stoer Peninsula; Rubha Coigach, Gruinard Bay-Loch Maree; east of the Coigach Fault, and west of the Moine Thrust.
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Coastal section between Clachtoll and Rubh' a' Mhill Dheirg, Stoer peninsula, northwest Highlands. 
Reference Section  South side of Enard Bay, between Achnahaird bay and Garvie bay. 
Reference(s):
Parnell, J., Mark, D., Fallick, T.E., Boyce, A. and Thackrey, S., 2011. The age of the Mesoproterozoic Stoer Group sedimentary and impact deposits, NW Scotland. Journal of the Geological Society of London, 168: 349 - 358. 
Rainbird, R.H., Hamilton, M.A. and Young, G.M., 2001. Detrital zircon geochronology and provenance of the Torridonian, NW Scotland. Journal of the Geological Society of London, 158: 15-27. 
Krabbendam, M. 2021. A stratigraphic framework for the early Neoproterozoic successions of the Northern Highlands of Scotland. UK Stratigraphic Framework Series. British Geological Survey Open Report, OR/21/072. 86pp. 
Darabi, M H, and Piper, J D A. 2004. Palaeomagnetism of the (Late Mesoproterozoic) Stoer Group, northwest Scotland: implications for diagenesis, age and relationship to the Grenville Orogeny. Geological Magazine, Vol. 141, 15-39. 
Stewart, A D. 2002. The later Proterozoic Torridonian rocks of Scotland: their sedimentology, geochemistry and origin. Geological Society Memoir. Vol. 24. (The Geological Society.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S101 S091 S092