Fear Liath

Ben MacDhui is the second highest mountain in the British Isles, rising to 4,295 feet in the Cairngorm range of the Scottish Highlands. It is not a technically difficult climb in summer, but its plateau is vast, exposed, and prone to sudden dense fog, and experienced climbers know it as one of the more psychologically unsettling peaks in Britain. The unease has a name: Am Fear Liath Mor, the Big Grey Man, a presence reported by climbers for over a century and taken seriously by people whose judgment on mountain matters is otherwise entirely sober.

The case entered public record in 1925 when Professor Norman Collie, an accomplished chemist at University College London and one of the most respected mountaineers of his generation, gave an address to the Cairngorm Club annual dinner in Aberdeen. Collie described an experience from his solo ascent of Ben MacDhui in 1891. Near the summit in thick mist, he began to hear footsteps behind him, crunching in the scree at a cadence not quite matching his own. Each step he took, he heard three or four crunches behind him. He told his audience, I was seized with terror and took to my heels, staggering blindly among the boulders for four or five miles nearly down to Rothiemurchus Forest. I will not go back there by myself I know. Collie was not a man given to hysteria or publicity-seeking, and his account drew other climbers forward with their own stories.

Subsequent reports have been remarkably consistent in their core elements. Climbers describe heavy crunching footsteps that fall between their own, a feeling of overwhelming panic and dread disproportionate to any visible threat, and occasionally a glimpse through the mist of a tall grey humanoid figure, sometimes described as over ten feet in height, with long arms and an indistinct face. In the 1940s, the naturalist Alexander Tewnion reported that he had drawn his revolver and fired three shots at an advancing figure on the mountain before fleeing. In more recent decades, mountaineers Richard Frere, Tom Crowley, and Peter Densham have all contributed detailed accounts. Densham, a wartime RAF mountain rescue officer with extensive experience on the peak, described being chased off the summit by a presence he could not see but could clearly hear behind him.

Proposed explanations include infrasound generated by wind over the granite plateau, which is known to induce feelings of dread in humans at frequencies around 19 Hz. The Brocken spectre, an optical phenomenon in which a climber's own shadow is projected onto fog and appears enormous, has been proposed as the source of the visual component. Altitude effects, exhaustion, and the psychological impact of dense fog on exposed terrain likely contribute. But none of these fully account for the reports of footsteps in synchrony with the climber's own, and Ben MacDhui has continued to produce fresh accounts into the 21st century, contributed not by thrill-seekers but by experienced mountaineers who would prefer to have seen nothing at all.