The BGS Lexicon of Named Rock Units — Result Details

Sangomore Formation

Computer Code: SGM Preferred Map Code: notEntered
Status Code: Full
Age range: Tremadoc Series (O1) — Arenig Series (OR)
Lithological Description: Fine-grained, granular dolostones, pale to dark grey in colour, although commonly pale cream coloured. Chert nodules and layers are common near the base. Towards the top there are bands of pink and cream limestone.
Definition of Lower Boundary: Conformably overlies the dark grey, chert-rich dolostones of the Sailmhor Formation.
Definition of Upper Boundary: Conformably overlain by dolomitic limestones of the Balnakiel Formation.
Thickness: Up to 180 m thick, measured as 60 m thick at Balnakiel Bay.
Geographical Limits: The Durness Group, which contains the Sangomore-Formation, forms a narrow, discontinuous belt, extending along the north-western side of Scotland from the Durness-Eriboll area, through Assynt and Kishorn, to Skye.
Parent Unit: Durness Group (DNG)
Previous Name(s): Sangomore Group (-1814)
Alternative Name(s): none recorded or not applicable
Reference Section  The lower part of the formation is exposed in the sea cliffs around Smoo Cave and in the cave itself, 1 km south-east of Durness. Peach et al., 1907. 
Reference Section  South coast of Balnakeil Bay, Durness area, north coast of Scotland. Peach et al., 1907, Prigmore and Rushton, 1999. 
Johnston, G S and Mykura, W. 1989. British regional geology: the Northern Highlands (4th edition) (London: HMSO for the British Geological Survey.) 
Park, E G, Stewart, A D and Wright, D T. 2002. The Hebredean Terrane. 45-80 in the Geology of Scotland. Trewin, N H (Editor). (The Geological Society, London.) 
Peach, B N, Home, J, Gunn, W, Clough, C T and Hinxman, L W, 1907. The Geological Structure of the northwest Highlands of Scotland. Memoir of the Geological Survey of Great Britain. 
Lapworth, C. 1883. The secret of the Highlands. Geological Magazine, Decade 2, Vol. 10, 120-128, 193-199, 337-344. 
Phemister, J. 1948. British Regional Geology: Scotland: the Northern Highlands (2nd edition) (Edinburgh: HSMO for the Geological Survey and Museum.) 
Prigmore, J K and Rushton, A W A. 1999. Scotland: Cambrian and Ordovician of the Hebridean Terrane. 295-315 in British Cambrian to Ordovician Stratigraphy. Rushton, A W A, Owen, A W, Owens, R M and Prigmore, J K (editors). Geological Conservation Review Series. (Joint Nature Conservation Committee.) 
Wright, D T and Knight, I. 1995. A revised chronostratigraphy for the lower Durness Group. Scottish Journal of Geology, Vol. 31, 11-22. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S071 S114