As a geologist, Greg Stock never imagined he'd witness the death of a glacier. The Lyell Glacier is Yosemite National Park's largest ice mass, and Stock has been researching it for more than a decade. The famed California scientist John Muir first studied the Lyell in the 1870s. But the glacier has slowly shrunk. Soon it will completely disappear. What do you call a glacier that no longer moves? Guest: Daniel Duane, San Francisco-based author. His essay What Remains was published in The California Sunday Magazine on April 4.