The soldiers at Matienzo Base in Antarctica made an odd discovery in January 1995—an antique dog sled, unlike any they had ever seen, bound together by leather straps, with a label reading “Made in England.”

Matienzo was an Argentine research base on a small island 30 miles off the coast of the Antarctic Peninsula. It was surrounded by a vast plain of white—a slab of glacial ice, 700 feet (215 meters) thick, that floated on the ocean. That floating slab, called Larsen A Ice Shelf, covered an area of water the size of San Francisco Bay. It had existed for a thousand years or more. But this hot summer it looked strange. The men had to go onto the ice shelf