The BGS Lexicon of Named Rock Units — Result Details

Croisaphuill Formation

Computer Code: CAP Preferred Map Code: notEntered
Status Code: Full
Age range: Arenig Series (OR) — Arenig Series (OR)
Lithological Description: Fossiliferous mid grey and dark grey dolomitic limestones and limestones with burrow mottling and chert nodules. Fossils include brachiopods, gastropods, cephalopods and trilobites.
Definition of Lower Boundary: Conformably overlies the Balnakiel Formation.
Definition of Upper Boundary: Conformably overlain by the Durine Formation.
Thickness: 120 - 145 m.
Geographical Limits: The Durness Group forms a narrow, discontinuous belt, extending along the north-western side of Scotland from the Durness-Eriboll area, through Assynt and Kishorn, to Skye. The Croisaphuill Formation does not occur in Assynt or Skye and appears to be limited to the more northern parts of the Durness Group's outcrop.
Parent Unit: Durness Group (DNG)
Previous Name(s): Croisaphuill Group (-108)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Rocky knolls in the scarp and slack topography east of Croispol Loch, near Durness. Peach et al., 1907; Prigmore and Rushton, 1999. 
Reference(s):
Lapworth, C. 1883. The secret of the Highlands. Geolgical Magazine, Decade 2, Vol. 10, 120-128, 193-199, 337-344. 
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.) 
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. 
Phemister, J. 1948. British Regional Geology: Scotland: the Northern Highlands (2nd edition) (Edinburgh: HSMO for the Geological Survey and Museum.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S114