Capitol Reef National Park's Geology: The Waterpocket Fold and 275 Million Years of Rock

Geodiversity is the full variety of a park's natural geologic and soil resources and processes — rocks, minerals, sediments, fossils, landforms and the processes that shape them. The NPS Geodiversity Atlas, a product of the Geologic Resources Inventory, supports education, geoconservation, and management of a park's living and non-living parts together. This is its page for Capitol Reef National Park, Utah.

The Geologic Resources Inventory report for the park.

The Land of the Sleeping Rainbow

Capitol Reef has some of the most spectacular geology in the western United States. For its brilliantly colored canyon walls, the Navajo people called it the Land of the Sleeping Rainbow. Its landscape includes the rugged spine of the Waterpocket Fold, high-walled gorges cut through it, monoliths, ridges, buttes and miles of colorful canyons.

The Waterpocket Fold

The park's centerpiece, the Waterpocket Fold, is one of the longest continuously exposed monoclines in the world — a step-like fold in the sedimentary rock.

• Length: almost 161 km (100 mi), from the Colorado River south of the Henry Mountains, along the east side of the Circle Cliffs, to the north end of Thousand Lake Mountain.
• Trend: northwest–southeast — about N 25° W between Oak Creek and the Fremont River, bending to N 50° W north of the Fremont.
• Height: the rock layers on the western side stand more than 2,100 m (7,000 ft) higher than on the east. To the west rise the High Plateaus; to the east lies the Canyon Lands section.
• The name: in this sparse desert, water has carved small basins — water pockets — in the tilted sandstone all along the fold.

Folds and faults

Other big structures are the Teasdale Anticline, the Teasdale Fault and the Thousand Lake Fault. Most major faults lie west of the fold; at the surface they are mapped as normal faults following the northwest–southeast trend, mostly shallow, though a few may reach down into the Precambrian. Below Capitol Reef, blind thrust faults — buried, with no surface expression — dip about 60° to the southwest through Precambrian to Mississippian rocks; younger layers are folded over them but not broken. Interpretations at depth are uncertain, because subsurface data are limited.

The park also has classic strike valleys, dikes and sills, gypsum domes, huge landslides, fossil oyster reefs, petrified logs, dinosaur bones, bentonite hills and unusual soft-sediment deformation. Named features include Cathedral Valley's cathedrals and monoliths, Glass Mountain and the Gypsum Sinkhole, "The Goosenecks" at Sulfur Creek, arches and bridges, Capitol Dome and Navajo Dome, cavernous weathering, slot canyons, unconformities and Ice Age deposits.

The Castle and Sulphur Creek. Image from the Park Service's page.

The rocks

The park's rocks run from Permian to Tertiary, recording 275 million years of Earth's history in open-sea, nearshore, river, lake and desert environments. The highest point is Blue Bell Knoll, 3,446 m (11,306 ft), a low rounded hill on top of Boulder Mountain, whose edges are cut by broad glaciated valleys; the smaller, flat-topped Thousand Lake Mountain lies to its north.

Fossils

NPS fossils are protected by the Paleontological Resources Preservation Act of 2009.

Uranium and other minerals

The park has been closed to mineral entry — oil and gas included — since it became a national monument in 1937, except from 1953 to 1955, when uranium exploration was allowed; it closed again after May 1955. The area holds uranium, vanadium, copper, manganese, gypsum, minor coal, building stone, sand and gravel, and oil and gas. Ten abandoned mine sites relate to uranium, and the Oyler mine in Grand Wash, located in 1901, is the area's oldest uranium-radium prospect. Mine waste piles are partly crusted with caliche, but pose a possible radiation hazard: don't camp on them or drink water nearby. Near any abandoned mine: stay out and stay alive.

Hazards

Flash floods and debris flows, swelling clays, uranium and radon contamination, rockfall and landslides, and earthquakes.

Region, maps and reports

The park lies in the Colorado Plateaus province. Its Geologic Resources Inventory report covers these features in depth. More: the park's geology pages and stratigraphy chart, and the Utah Geological Survey.

The park's geologic map from the Geologic Resources Inventory.

Sources

Based on "NPS Geodiversity Atlas—Capitol Reef National Park, Utah," National Park Service, drawing on Smith et al. (1963), Billingsley et al. (1987), Santucci et al. (1998), Morris et al. (2000), Koch and Santucci (2002) and Mickelson (2004); a work of the United States government in the public domain.