STS045-152-056 Tobacco Root Mountains, Beaverhead River, and Ennis Lake, Montana, U.S.A. March 1992 This near-vertical photograph shows the valleys of the Beaverhead, Madison, and Jefferson Rivers. The confluence of three rivers near the barely discernible city of Three Forks forms the headwaters of the Missouri River (bottom right of photograph). The snow-covered, rugged Tobacco Root Range, from which were mined gold and silver until the early 1900s, consists mostly of Precambrian basement rocks with a core of granite emplaced about 70 million years ago. East of the Tobacco Root Range lies Ennis Lake. The Highland Range and the smaller McCartney Mountain Range are visible in the upper portion of the photograph.