The time is 1 p.m., May 24, 1869. The place: the Green River portage, in present-day Wyoming. The personnel are ten: Major John W. Powell, one-armed Civil War veteran, later head of the U. S. Geological Survey) and nine geologists, geographers, scouts, and adventurers. Their assignment: to fill in the last white space on the map, to explore the last great unmapped and unknown part of the continental United States.No man has ever descended the Colorado River — some 1,000 miles cut...
