Underland: A Deep Time Journey

by Robert Macfarlane

The ground begins to fall away to the left of the path. We are soon on the edge of a huge doline, perhaps 150 feet across. The far side is near vertical, but our side slopes at fifty degrees or so, and a thin track switchbacks down into the chasm, where a cave mouth gapes. With each hairpin of the path, the air chills around us. I have never before experienced such a precipitous temperature gradient. Thirty degrees Celsius at the doline’s edge becomes twenty-five degrees Celsius within sixteen vertical feet, and so it drops as we drop, and though we pushed first through tepid air, soon an evening cool is around us, and then as we approach the cave mouth, 100 feet down, the air prickles cold as metal in the nose, our breath feathers in front of us and then we pass into a fine silver mist – the breath of the glacier itself. The steep temperature gradient produces a steeply raked ecology. The trees shrink in size with each turn of the path, from towering beeches to bonsai pines near the cave’s belly, clinging on in the arctic temperatures. By the entrance to the maw, where the temperature rarely rises above freezing, there is only moss and lichen matting – a low polar tundra. The smells at this depth are wholly different from those of the Carso and the forests; instead of heat, herbs, resin and stone, here is moss, winter and ice. Lucian and I scramble down a short slab of rock, cross the threshold of the cave and step into darkness. I glance back up through the mist to see a...