Black Canyon of the National Gunnison Park

We visited this park today - not far from Montrose in Colorado. Quite spectacular, sheer cliffs drop almost 2,000 ft to the river. We drove down a very steep windy road to the bottom where an amazing 6 mile long tunnel was built back in the very early 1900s to carry water out to irrigate dry, arid lands, which is still does today.
"The canyon walls are composed of volcanic schist, predominantly black in color, and as the gorge reaches depths of over 2,000 feet while often being only 1,500 feet across, sunlight illuminates the walls only briefly, hence the name Black Canyon. It is unsettling, almost frightening to stand at the very edge of one of the canyon overlooks, such is the menace and sheerness of the jagged rocks below". - The American Southwest.