The Grampian Group is an estimated 9,000 m thick sequence of metamorphosed Neoproterozoic sedimentary rocks that outcrop across the Central Highlands of Scotland, east of the Great Glen.
[1] The Glenshirra Subgroup is the lowermost (oldest) part of the succession.
These rocks reflect deposition within shallow marine and fluvial environments.
It is overlain by the thick sequence of proximal and distal turbidites of the Corrieyairack Subgroup which is in turn overlain by the Glen Spean Subgroup reflective of the infilling of the Corrieyairack, Strath Tummel and Cromdale depositional basins.
The Bowmore Sandstone of the Highland Border Complex is correlated with the Corrieyairack Subgroup.