Robert Macfarlane’s Underland (W.W. Norton, $27.95) is profound in all senses of the word. In it he explores the “deep time” of caves, glaciers, and burial chambers as well as reflecting on the meaning of our most ancient myths and primal dreams. It’s no accident that the title rhymes with Wonderland: here are wonders galore, from the magnificent geological formations of limestone and karst to the earliest human art in Lascaux and Chauvet to the myriad surprises waiting in the Paris catacombs. Here also is the wonder of Macfarlane’s prose; rhythmic, dramatic, and fluent in the rich vocabulary of geology, glaciology, and their emotional analogs, Macfarlane is spellbinding as he describes the look, feel, and sound of extreme cold; the amazing variety of blues in a Greenland glacier; and the remarkable life cycle of stone, which, seen in deep time, “folds as strata, gouts as lava, floats as plates, shifts as shingles.” But if the underland is where we store “that which we love and wish to save,” it’s also where we hope to unburden ourselves of “that which we fear.” Macfarlane found as many nightmares as wonders in his travels, and the anthrax spores released by melting permafrost and tons of radioactive nuclear waste also threaten those of us who stay safely on the surface.