Zion Canyon - Geology and History

Geology and History

Geologically Zion Canyon is part of the Navajo sandstone Colorado Plateau, which contained many joints and cracks when first uplifted, one of which was cut by the North Fork of the Virgin River to become Zion Canyon. The river was the largest force in cutting the canyon, mostly by flash floods, as the average flow of the river is very light. This relatively quick downcutting has left many seasonal tributaries with hanging valleys. Some of the largest tributaries have cut down to nearly an equal elevation as the valley floor.

Erosion continues to sculpt the canyon walls, creating natural arches and other rock formations. It is believed that there is another 1,000 feet (300 m) of vertical bedrock that the Virgin River can still erode. Mass wasting, often caused by ice wedging into cracks in the canyon walls, is another force that widens the valley. The Navajo Sandstone formation is easily eroded and is known to be very porous. Unstable geology is prevalent throughout the canyon, and occasional rockslides have formed impounded lakes in the canyon, the most recent of which was roughly 4,000 years ago. Owing to the extreme depth of the canyon, there are many springs fed by the surrounding groundwater, permitting water in the canyon to run year round.

The first settlers in Zion Canyon were Mormons that migrated from the lower Virgin River area in the late 1850s. The canyon was named by settler Isaac Behunin, who named the canyon after a "place of peace" mentioned in the Bible. Explorer John Wesley Powell is credited with the name Mukuntuweap, supposedly the native name of the canyon. In 1909, the canyon was first declared a national monument, and in 1919 was declared a national park. The Zion-Mount Carmel Highway, cutting through Pine Creek Canyon and lower Zion Canyon, first opened in 1930.