The BGS Lexicon of Named Rock Units — Result Details

Coire nan Laogh Semipelite Formation

Computer Code: CNLH Preferred Map Code: CL
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Schistose to gneissose semipelite, garnetiferous, with interbanded micaceous psammite. Minor feldspathic and siliceous psammite beds; calc-silicate lenses common.
Definition of Lower Boundary: Sharp contact with underlying grey feldspathic psammites of the Gairbeinn pebbly psammite member - well exposed in Garbh Choire [NN 4628 9895] and south of Uinneag Mhin Choire [NN 4651 9955].
Definition of Upper Boundary: Transitional through upper psammite and semipelite unit defined by incoming of thick turbiditic psammites of the Loch Laggan Psammite Formation.
Thickness: c. 500 m.
Geographical Limits: Central Highlands of Scotland, sheets 63W, 63E and 74W.
Parent Unit: Corrieyairack Subgroup (GRCO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Reference Section  Northeast flank of A'chailleach. Top and basal contacts well-exposed. 
Type Section  Summit area of Gairbeinn [2940'] to Coire nan Laogh. Basal contact well exposed. 
Key, R M, Clark, G C, May, F, Phillips, E R, Chacksfield, B C and Peacock, J D, 1997. Geology of the Glen Roy district. Memoir of the British Geological Survey, Sheet 63W [Scotland]. 
Haselock, P J, Whinchester, J A and Whittles, K H, 1982. The stratigraphy and structure of the southern Monadhliath Mountains between Loch Killin and Upper Glen Roy. Scottish Journal of Geology, Vol. 18, p. 275 - 290. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S074 S063 S063