In winter, storm winds of up to 170 miles per hour rasp the upper shires of the range, and avalanches scour its slopes. Even in high summer, snow still lies in the deepest corries, sintering slowly into ice. The Northern Lights flare green and red above its summits. The wind is so strong that on the plateau there are bonsai pines, fully grown at six inches, and juniper bushes which flatten themselves across the rocks to form densely woven dwarf forests. Two of Scotland’s great rivers – the Dee and the Avon – have their sources there: falling as rain, filtered by rock, pooling as the clearest water into which I have ever looked, and then running seawards with gathering strength. The range itself is the eroded stump of a mass of magma that rose up through the earth’s crust in the Devonian, cooled into granite, then emerged out of the surrounding schists and gneiss. The Cairngorms were once higher than today’s Alps, but over billennia they have been eroded into a low-slung wilderness of whale-backed hills and shattered cliffs.