Bryce Canyon is famous for the surreal "hoodoos" – tall, thin spires of colorful rock – that cover much of the park. This landscape is like no other place on earth.
Hoodoos are formed by natural erosion of the alternating hard and soft rock layers that make up the Claron Formation in southwestern Utah. An ancient lake bed 30 to 40 million years ago, this layer is predominately limestone. Minerals deposited in the various rock types give hoodoos their vibrant colors.
Hoodoos are formed by two weathering processes that work together to erode the layers of rock. The primary weathering force is "frost wedging." At Bryce Canyon, there are more than 200 freeze/thaw cycles each year. Melting snow seeps into cracks in the rock during the day and freezes at night, expanding by almost 10% and gradually prying open the cracks. In addition to frost wedging, the little rain that falls in Bryce Canyon is slightly acidic and slowly dissolves the limestone, rounding the edges of the hoodoos and giving them their lumpy and bulging profiles. Many of the more durable hoodoos are capped with a special kind of magnesium rich limestone called dolomite, which dissolves at a much slower rate and thus shields the weaker limestone underneath it.
Although the hoodoos can be seen from many vantage points on the rim of Bryce Canyon by taking just a few steps from the car, one of the great joys of the park is a hike on the canyon floor through the forests of towering rock. The Queen's Garden trail was particularly scenic.
For more information about U.S. National Parks in general, visit the web site of the National Park Service.