Thousands of delicately carved limestone spires called hoodoos help make up the dramatic landscape of Bryce Canyon National Park in Utah, USA. Hoodoos are columns that typically consist of relatively soft rock capped by harder, less easily eroded, stone that protects the spire beneath it. Some hoodoos at Bryce reach 45 meters in height. Hoodoos that form a thin wall are called fins. Limestone is ordinarily white, but the hoodoos at Bryce are coloured by impurities, including iron oxide making the stone brown, yellow, or red. Bryce is part of the Grand Staircase, an immense sequence of exposed sedimentary rock layers that stretch two hundred kilometres in the American Southwest and feature some of the most dramatic scenery anywhere in the world