October 1998

Jim Webster and Graham Stewart go on expedition to the Grand Canyon and surrounding area with Museum coworkers and a team of mold makers to make a cast of sedimentary layers and features, and to collect boulders of sandstone and limestone. The layers and features of these sedimentary rocks provide a vast amount of information that allows geologists to interpret, or "read," the rocks. A Scientists at Work video featuring Jim and two geologists who specialize in the geology of the Grand Canyon is also shot during this expedition.

A scenic view from the rim of the Grand Canyon in Sonoma County, Arizona. The canyon's sculptor, the Colorado River, runs along its floor, nearly two kilometers below the rim. One of the most dramatic examples of the power of rivers to erode landscapes, the walls of the canyon reveal rock strata that date from 1.8 billion to 250 million years ago.

photo credit: Denis Finnin, © American Museum of Natural History