Underland: A Deep Time Journey

by Robert Macfarlane

Another valley is sheer-sided on its eastern flank, with 400-foot-high white cliffs rearing almost from the road. Plumb in the centre of one is a cave mouth, and out of that mouth roars a silver river which plummets to a plunge pool at the cliff’s base. Rainbows drift in the spray. I have never seen a feature like it. It defies all the usual geological and fluvial rules. Rivers are not meant to issue from the centre of cliffs. But then the earth is not meant to have tides, and mountains are not meant to have windows – and caves are not meant to grow glaciers. We find the glacier-cave sunk high in the mountains, where the beech trees grow to sixty feet or more and the canopy is so thick we can hardly see the sky. We follow a thin contouring path, knotty with tree roots, through the forest. The air is heavy, hot. As we walk, Lucian explains the glacier’s existence to me, but I can hardly believe what he is saying to be true. A flowing river of ice at this height, in this heat? There is no lying snow for many miles around. ‘This cave system is a mile in length, nearly 400 metres deep, and it perforates an entire mountain from one side to another,’ says Lucian. ‘The free movement of wind along the cave system, combined with the chill of the rock itself, keeps the temperatures within the system well below freezing. Snow gathers in the cave mouths in the winter, blown deep into it by the northerly winds, and – hey presto! – over thousands of years, the snow becomes a long thin g...