Two hundred miles upstream from Glen Canyon Dam, the Colorado River roars through Cataract Canyon in a rust colored tumult, thick with silt and clay. Each year, the Colorado and its tributaries carry, on average, some 61 million cubic yards of sediment into Lake Powell, enough to fill more than 200,000 railroad boxcars.
More than a century ago, a Harvard undergraduate named Alfred Vincent Kidder came out west. He came to volunteer at some archaeological sites that had just been excavated - places like Mesa Verde and other ancient ruins.
Nicknamed Ted, he had little more than a tape measure, a cheap compass and a Kodak camera. But the experience changed his life - and the course of southwestern archaeology.