The BGS Lexicon of Named Rock Units — Result Details
Ghrudaidh Formation
Computer Code: | GUD | Preferred Map Code: | notEntered |
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Status Code: | Full | ||
Age range: | Comley Series (EC) — Comley Series (EC) | ||
Lithological Description: | Dark to mid-grey dolostones containing burrow mottling, oolitic and bioclastic grainstones and rare stromatolites. | ||
Definition of Lower Boundary: | Conformably overlies the Salterella Grit Member of the An T'Sron Formation. The boundary is gradational over about a metre. | ||
Definition of Upper Boundary: | Conformably overlain by pale grey and buff flaggy dolostones of the Eilean Dubh Formation. A zone of interbedded dark and pale grey dolostones occurs at the boundary. The actual contact with the Eilean Dubh Formation is taken at the appearance of laminations and/or chert layers. | ||
Thickness: | From 50 m to 60 m thick. | ||
Geographical Limits: | The Durness Group , including the Ghrudaidh 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): | Ghrudaidh Group [Obsolete Name and Code: Use GUD]
(-3448)
Ghrudaidh Formation [Also Grudaidh Formation] [Obsolete Code: Use GUD] (GRU) |
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Alternative Name(s): | Grudaidh Formation |
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Stratotypes: | |||
Reference Section | Good exposures of the Ghrudaidh Formation occur near Skaig Bridge, Loch Assynt, and around Inchnadamph and the Stronchrubie cliffs. The grid ref. Below is for a section near Skaig Bridge which shows the lower boundary. Peach et al. , 1907. | ||
Type Area | Shores and hillslopes around Grudie, Durness area, north coast of Scotland. Peach et al., 1907; Prigmore and Rushton, 1999. | ||
Reference(s): | |||
Johnston, G S and Mykura, W. 1989. British regional geology: the Northern Highlands (4th edition) (London: HMSO for the British Geological Survey.) | |||
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.) | |||
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. | |||
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.) | |||
Huselbee, M Y, and Thomas, A T. 1998. Olenellus and conodonts from the Durness Group, NW Scotland, and the correlation of the Durness succession. Scottish Journal of Geology, Vol. 34, 83-85. | |||
Lapworth, C. 1883. The secret of the Highlands. Geological 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.) | |||
Phemister, J. 1948. British Regional Geology: Scotland: the Northern Highlands (2nd edition) (Edinburgh: HSMO for the Geological Survey and Museum.) | |||
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: | |||
S114 S071 S107 S108 S081 S101 |