Go to Morrison, Colorado, just west of Denver. There, as you take in the Moody Blues concert at Red Rocks Amphitheater, you can study the spectacular formations that jut from the Front Range of the Rockies. Not only is their color astounding, against the tamer colors of the Rockies, but the angle of the formations lends them a kind of intimidating presence— they are tilted at a 45-degree angle to the bedrock. If you drive south, to Colorado Springs, this same redrock formation erupts into Garden of the Gods, the nearly surreal pocket park of hoodoos and huérfanos. Technically speaking, redrock is predominantly granophyric rock of a red color. The red is usually due to iron oxides—the cliffs are rusting. Drillers on rock-blasting teams call all reddish sedimentary rocks of shale, sandstone, or limestone origin “redrock.” Redrock country is widely used as a synonym for all or parts of the Colorado Plateau.