A portion of the deep Black Canyon of the Gunnison (River), near Montrose in Montrose County, Colorado. The chasm at this U.S. national park exposes visitors to some of the steepest cliffs, oldest rock, and craggiest spires in North America. With two million years to work, the Gunnison River, along with weathering forces, sculpted this vertical wilderness of rock, water, and sky. Photo by Carol Highsmith, 2015.