Black Canyon of the Colorado Black Canyon of the Colorado The Black Canyon of the Colorado is the canyon on the Colorado River where Hoover Dam was built. The canyon is located on the Colorado River at the state line between Nevada and Arizona. The western wall of the gorge is in the El Dorado Mountains, and the eastern wall is in the Black Mountains of Arizona. The canyon formed about 15 million years ago during the Miocene Basin and Range uplift. Black Canyon gets its name from the black volcanic rocks that are found throughout the area. Just south of the Hoover Dam on
Steamboats of the Colorado River shared information about the conditions on the river above them. Robinson piloted the "Explorer" above the point reached by Johnson into the Black Canyon of the Colorado, where they struck a rock that damaged the boat, 40 miles above where Johnson reached. Ives named that rock "Explorer's Rock". While the "Explorer" was being repaired by his engineer, Ives, Robinson and the boat's mate, took their skiff over the next two days farther up the river exploring up through the Black Canyon and beyond to the vicinity of Fortification Rock. Next day, they went two miles farther to Las Vegas Wash,