The BGS Lexicon of Named Rock Units — Result Details

Eilean Dubh Formation

Computer Code: ELD Preferred Map Code: notEntered
Status Code: Full
Age range: St David's Series (ED) — Tremadoc Series (O1)
Lithological Description: Pale grey to buff, flaggy, laminated dolostones with intraformational breccias and minor chert development towards base and top of unit. Stromatolites particularly abundant in Durness area.
Definition of Lower Boundary: Conformably overlies dark grey dolostones of the Ghrudaidh Formation. A zone of interbedded dark and pale grey dolostones occurs at the boundary. The base of the Eilean Dubh Formation is taken at the appearance of laminations and/or chert layers.
Definition of Upper Boundary: Conformably overlain by dark dolostones and white chert of the Sailmhor Formation.
Thickness: About 150 m thick.
Geographical Limits: The Durness Group, which contains the Eilean Dubh 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): Eilean Dubh Group (-2781)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Eilean Dubh, is a small island/peninsula on the south-west side of Balnakeil Bay, near Durness, on the north coast of Scotland. Peach et al., 1907; Prigmore and Rushton, 1999. 
Reference Section  Good exposures although disrupted by thrusts, occur around Inchnadamph and the Stronchrubie cliffs in Assynt. The latter are mainly inaccessible, except in the lower parts of the cliffs and at the north and south ends. Peach et al. (1907) 
Reference(s):
Johnston, G S and Mykura, W. 1989. British regional geology: the Northern Highlands (4th edition) (London: HMSO for the British Geological Survey.) 
Phemister, J. 1948. British Regional Geology: Scotland: the Northern Highlands (2nd edition) (Edinburgh: HSMO for the Geological Survey and Museum.) 
Cowie, J W. 1974. The Cambrian of Spitsbergen and Scotland. 123-155 in Cambrian of the British Isles, Norden and Spitsbergen, Holland, C H (editor). Lower Palaeozoic Rocks of the World, Vol. 2. (John Wiley and Sons.) 
Lapworth, C. 1883. The secret of the Highlands. Geolgical Magazine, Decade 2, Vol. 10, 120-128, 193-199, 337-344. 
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.) 
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. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S114 S071 S107 S108 S081 S101 S102