Underland : A Deep Time Journey

It is the third of his books to work outward from a single idea — after the mountains of Mountains of the Mind and the paths of The Old Ways — and the most unsettling of them. The journey runs from the Mendip caves to the catacombs of Paris, from a potash mine a kilometre beneath the North Sea to the blue depths of a Greenland glacier, and ends at a Finnish repository built to hold nuclear waste safely for a hundred thousand years. Along the way he descends into the "wood wide web" of fungal networks by which trees feed and warn each other, and into Slovenian caves where rivers vanish into the rock. What holds it together is deep time — the geological scale on which a human life is not even an event. Macfarlane is interested in what that scale does to a person who takes it seriously, and in what we are leaving behind for readers who will not share our language, our species memory, or our warnings. It is a demanding book and an unusually physical one; the claustrophobia of the tighter passages is not something he spares you. Readers who came to him through the walking books will find the same ear for landscape and a much darker register.