The Grampian Group; a major late Proterozoic clastic sequence in the Central Highlands of Scotland

The Grampian group is divided into three subgroups. The thin Ord Ban subgroup, developed locally at the base of the Grampian group on Speyside and Strath Dearn, consists of shallow marine shelf sediment in association with concordant amphibolite sheets. Elsewhere, the Corrieyairack subgroup forms the lowest part of the Grampian group and comprises a thick turbiditic clastic sequence laid down in deeper water during rapid basin subsidence. The Glen Spean subgroup forming the upper part of the Grampian group is composed of shallow water, tidal and gammaic deposits.