The Meall Dearg Formation is a 1.2 Ga fluvial-aeolian sandstone exposed in the northwestern Highlands of Scotland, and represents one of the least studied rock units in the Torridonian succession, especially in terms of sedimentary provenance. Three hundred and nine detrital zircon grains were analysed from four samples of the Meall Dearg Formation using sensitive high-resolution ion microprobe, allowing for its provenance to be resolved at the terrane scale. Ages range from c. 3,100 to c. 1,750 Ma, with dominant proportions between c. 2,900 and c. 2,650 Ma, and subordinate fractions of c. 2,500 Ma and c. 1,900 Ma. U-Pb protolith-zircon ages from eight previous studies across the Lewisian Gneiss Complex were compiled and compared to detrital-age distributions of the Meall Dearg Formation. Strong similarities in age trends and palaeocurrent data corroborates the hypothesis of sedimentary provenance from the Lewisian Gneiss Complex. Detritus was prevalently derived from the Rhiconich and Gruinard terranes, and subordinately from the Assynt, Gairloch (including the Loch Maree Group and Ard Gneiss), and Ialltaig terranes. Age distributions from the fluvial and aeolian samples show near-matching distributions, indicating sediment transfer between adjacent depositional environments, and possibly derivation from similar source regions. The Meall Dearg Formation, part of the Stoer Group, is postulated to record the overfilling stage of a rift basin near the eastern flank of the Columbia Supercontinent at c. 1.2 Ga. Critical comparisons can be drawn between the Stoer Group and Gardar Rift of southern Greenland, based on their age, palaeogeography, and patterns of rift-basin development.