Ice once covered most of North America. Today, Alaska, with its approximately 100,000 glaciers, is a living example of its profound influence. The state's rugged landscape is a textbook of glacial activity, and geologist and photographer Michael Collier guides you through its pages. In the company of scientists studying this ancient ice, he approaches the great sleeping beasts on foot, crampons snugly strapped on; from a kayak, rocking gently in an icefall's wake; and from the air, through the window of a small plane. Follow him across the tricky terrain of glacial terms and geologic time; it's a journey well worth taking.