As you head south from Durness, heather gradually gives way to a rockier landscape of Lewisian gneiss pockmarked with hundreds of small lochans. This is the most interesting zone geologically in the UK, with Britain's oldest rock. Next come gorse-covered hills prefacing the magnificent Torridonian sandstone mountains of Assynt and Coigach, including Suilven's distinctive sugarloaf, ziggurat-like Quinag and pinnacled Stac Pollaidh. This area has been named as the Northwest Highlands Geopark.