Down the Great Unknown by Edward Dolnick

On May 24, 1869, a one-armed Civil War veteran named John Wesley Powell and a ragtag band of nine mountain men embarked on the last great quest of the American West. No one had ever explored the fabled Grand Canyon. To adventurers of that era it was a region almost as mysterious as Atlantis -- and as perilous.

In May 1869, a one-armed Civil War veteran and a ragtag band of nine mountain men embarked on the last great quest in the American West: the fabled Grand Canyon. Drawing on rarely examined diaries and journals, this is the first book to tell the full, dramatic story of John Wesley Powell's expedition. 16-page photo insert. Maps and index.