Black Canyon of the Gunnison

Declared in 1999, the Black Canyon of the Gunnison owes its name to how little light reaches its floor: at its narrowest and deepest point, the walls — some of the most vertical in North America — get direct sunlight for barely 33 minutes a day, even at midsummer. The river Gunnison has taken almost 2 million years to cut the canyon through some of the oldest rock exposed at the surface anywhere in North America, at almost 2,000 million years old.