Black Canyon of the Gunnison, Colorado

The Black Canyon of the Gunnison is very impressive.  48 miles long and 2,770 ft deep, it was formed by hard rock uplifted then cut through by the fast-flowing Gunnison River for two million years.  It is named "black" not only for it's rock colour, but also because it is so deep, so sheer and so narrow that very little sunlight can penetrate down to the canyon floor.

It has been a mighty barrier to human migration, with only its rims, never the gorge showing evidence of human occupation.