April 30, 2007
The Waterpocket Fold is the definitive feature of Capitol Reef National Park in southern Utah. A nearly 100-mile (160 km) long warp in the Earth's crust, this fold is a classic monocline: a regional fold with one very steep side in an area of otherwise nearly horizontal layers. A monocline is a "step-up" in the rock layers. The rock layers on the west side of the Waterpocket Fold have been lifted more than 7,000 (2,134 m) feet higher than the layers on the east.
The Waterpocket Fold formed between 50 and 70 million years ago when a major mountain building event in western North America, the Laramide Orogeny, reactivated an ancient, buried fault. Major folds are almost always associated with underlying faults. Photo taken by Chuck Strickland.