The Northwest Highlands are located in the northern third of Scotland that is separated from the Grampian Mountains by the Great Glen (Glen More). The region comprises Wester Ross, Assynt, Sutherland and part of Caithness. The Caledonian Canal, which extends from Loch Linnhe in the south-west, via Loch Ness to the Moray Firth in the north-east splits this area from the rest of the country. The city of Inverness and the town of Fort William serve as gateways to the region from the south.
The geology of the Highlands is complex. Along the western coastal margin it is characterised by Lewisian gneiss, the oldest rock in Scotland. Liathach, Beinn Alligin, Suilven, Cùl Mòr, Cùl Beag, and Quinag are just some of the impressive rock islands of the significantly younger rich brown-coloured Torridonian sandstone which rests on the gneiss. Some of the peaks, such as Beinn Eighe and Canisp, are topped with later light grey or white Cambrian quartzite. Cambro-Ordovician limestone is also to be found in a narrow outcrop between Durness and Skye. The larger part of the region is formed from rocks of the Moine succession much of which is metamorphosed sandstones (psammites) and schist. These have over-ridden the gneiss and the Cambrian and Ordovician rocks of the northwest margin along the Moine Thrust Belt.
This area's climate is dominated by the warming influence of the Gulf Stream. It has warm, wet summers on average under 17° C, or 62.6° F. The winters are mild at low altitude but become snowier and colder with higher elevation, at an average of about 0° C, or 32° F. Naturally, the area would be a vast birch, pine and montane shrub forest, such as those surviving in Glen Affric. Snow may lie from more than a month to 105 days, but not at coastal or high altitudes.
The region has steep, glacier-carved mountains, glens and interspersed plains. Many islands (which also vary widely in geography) lie off the coast. Elevations of around 750 metres (2500 ft) or over are common, as are mountains exceeding 3000 feet or 914 m (Munros). In comparison, across the Great Glen to the south of the region the Nevis range reaches over 1300 metres and includes the highest point in all of Britain; while to the east are the Cairngorms with summits above 1200 metres and a plateau which is the coldest place in Britain.
The Northwest Highlands are typically not quite as cold as the Cairngorms. Considering its terrain and its latitude of about 57 to 58 degrees North, the area is surprisingly warm: this is due to the mild influence of the Gulf Stream. The aurora borealis is sometimes visible on winter nights, especially at the climax of the 11-year cycle. Bordering the region to the north east is the lowland area of Caithness. There are relatively few roads, and many are single lane (with passing places). The region has a very low population density. Significant settlements are Kyle of Lochalsh, Mallaig, Dingwall, Dornoch, and Ullapool. The city of Inverness, known as the "Capital of the Highlands", on the eastern margin of the Northwest Highlands, is by far the largest settlement in the region and is the administrative centre for the Highland Council area.