[2] The formations of north-western Scotland were once part of a fragment of a then continuous south-eastern margin of Laurentia stretching from western Newfoundland to north-eastern Greenland, which at the time (and prior to the opening of the Atlantic Ocean) were contiguous to the west and to the north respectively.

Fenestral carbonates, oolites, evaporate pseudomorphs, stromatolites and finely-laminated dolomites with desiccation cracks and teepees were deposited in a supratidal to shallow subtidal setting.

In more open marine conditions during maximum flooding events, the Sailmhor and Croisaphuill formations of the Durness Group saw burrowed carbonate mud dominated deposition.

[6] The thick dolostone and limestone beds succession of the Ghrudaidh Formation, the lowest part of the Durness Group, was formed in a range of supratidal, peritidal and shallow marine carbonate platform deposits.

[2] The Durine Formation of the group has the youngest deposition in the Scottish sector of the Laurentian margin prior to the Grampian Orogeny.