The BGS Lexicon of Named Rock Units — Result Details

Portree Shale Formation

Computer Code: PEE Preferred Map Code: Pee
Status Code: Full
Age range: Toarcian Age (JT) — Toarcian Age (JT)
Lithological Description: Dark grey/black mudstones of anoxic deposition dominate the succession, which is locally laminated, organic-rich and contains few benthic fossils. Poorly exposed.
Definition of Lower Boundary: Abrupt lithological change from sandstone of the Scalpay Sandstone Formation (SCS) to anoxic mudstone.
Definition of Upper Boundary: Passes up gradationally from organic-rich shales of the Portree Shale Formation to ironstone of the Raasay Ironstone Formation (RASI).
Thickness: 2 m+
Geographical Limits: Sea of the Hebrides Basin.
Parent Unit: Lias Group (LI)
Previous Name(s): Portree Shale [Obsolete Name and Code: Use PEE] (-2970)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Tributary of the Inverarish Burn northeast of the main opencast workings [NG 5718 3689], Raasay. 
Reference Section  Roadside south of Faoilean [NG 5685 1972]. 
Partial Type Section  South of Dun Liath ruins, near Elgol, Strathaird, Skye. Morton and Hudson, 1995. 
Reference Section  Coastline east of the Trotternish Ridge, Skye. Morton and Hudson, 1995. 
Reference(s):
Emeleus, C H, and Bell, B R. 2005. British Regional Geology: the Palaeogene volcanic districts of Scotland (4th edition). (Nottingham: British Geological Survey.) 
Morton, N and Hudson, J D, 1995. Field Guide to the Jurassic of the Isles of Raasay and Skye, Inner Hebrides, north-west Scotland. In: Taylor, P D (editor), Field Geology of the British Jurassic. Geological Society of London, 209-280. 
Morton, N. 1965. The Bearrenaig Sandstone Series (Middle Jurassic) of Skye and Raasay. Scottish Journal of Geology, Vol.1, 189-216. 
Fyfe, J A, Long, D, and Evans, D, 1993. United Kingdom offshore regional report: the geology of the Malin - Hebrides sea area (London: HMSO for the British Geological Survey.) 
Cox, B M, Page, K N, and Morton, N. 2002. The Middle Jurassic stratigraphy of Scotland. In British Middle Jurassic Stratigraphy. Cox, B M, and Sumbler, M G (editors). Geological Conservation Review Series, Vol. 26. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S071 S080 S081 S051 S052