[1] It is exposed along the Dalradian outcrop from Galway, Mayo and Donegal in Ireland in the west through Islay and the Garvellachs in the Inner Hebrides to Schiehallion, Braemar and Fordyce to the east on mainland Scotland.

This area has been identified as a major depocentre for the Argyll Group, possibly as a result of active extensional faulting.

In this central area the sequence is extremely well exposed and the deformation state is generally low, meaning that original sedimentary structures are well-preserved, allowing for confident environmental interpretation.

The sequence contains 48 beds of diamictite interbedded with sandstones of non-glacial origin, forming 35–40% of the unit, typically deposited in deltaic to shallow water marine environments.

[3] During the Neoproterozoic cold period, the Cryogenian, there are two globally distributed glacial sequences, the older Sturtian glaciation (~717–660 million years ago} and the younger Marinoan glaciation (<654–632 million years ago), both of which are regarded as probable examples of a Snowball Earth, where ice sheets extended to very low latitudes.

Rhenium–osmium dating has been carried out on pyrite grains found within layered baryte deposits that are part of the Easdale Subgroup of the Argyll Group.