Black Canyon, Colorado River, Looking Below Near Camp 7

By 1870, government expeditions to the West were routinely documented by photographs. In 1871 and 1873, O'Sullivan joined the U.S. Army's survey of Nevada, Utah, and Arizona, under the command of Lt. George M. Wheeler. Despite the practical limitations of early photographic techniques, O'Sullivan's images not only record breath-taking vistas, but also capture the energy and adventurous spirit of these early expeditions. The deceptively serene surface of the water in this image is an illusion created by the long exposure of the negative. In 1936, the flow of water through the Black Canyon area was substantially altered by the completion of the Hoover Dam just up-river from the site.