The BGS Lexicon of Named Rock Units — Result Details

Glen Spean Subgroup

Computer Code: GRGS Preferred Map Code: GRGS
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Dominantly siliceous, feldspathic and micaceous psammite with some quartzite. Semipelite developed locally near the base.
Definition of Lower Boundary: Transition up from graded micaceous psammites of the Corrieyairack Subgroup into clean feldspathic and siliceous psammites.
Definition of Upper Boundary: First appearance of regionally transgressive semipelites of the overlying Lochaber Subgroup (Appin Group).
Thickness: To 2km
Geographical Limits: Glen Spean, Lochaber and the Central Grampian Highlands of Scotland.
Parent Unit: Grampian Group (GRAM)
Previous Name(s): Strath Tummel Succession (-4072)
Alternative Name(s): none recorded or not applicable
Reference Section  Glen Spean around Inverlair Falls. 
Type Section  A9 road section NW from Calvine to Dalnaspidal. 
Winchester, J A and Glover, BW, 1988. The Grampian Group, in Winchester, J A [ed.]. Late Proterozoic stratigraphy of the northern Atlantic regions. Blackie, Glasgow, 146-161. 
Glover, B W and Winchester, J A, 1989. The Grampian Group, a major Late Proterozoic clastic sequence in the Central Highlands of Scotland. Journal of the Geological Society, London. Vol.146, 85-96. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S062 S063 S063 S053 S054 S046