Geology of Rocky Mountain National Park, Colorado

Part of the NPS Geodiversity Atlas, which describes each park's significant geologic features and processes. Geodiversity is the full variety of a park's natural geologic resources — rocks, minerals, sediments, fossils, landforms and physical processes — and its soils. The atlas comes from the NPS Geologic Resources Inventory.

The park's Geologic Resources Inventory report. Image from the NPS's page.

The park

Rocky Mountain National Park (ROMO), established on January 26, 1915, lies in Boulder, Grand and Larimer Counties in northern Colorado. Its 107,563 hectares (265,795 acres) hold mountain meadows, snow-fed streams, rolling alpine uplands, glacial moraines and valleys, and volcanoes, lava and ash. Its peaks form the Continental Divide, Trail Ridge, the Mummy Range and the Never Summer Mountains.

Longs Peak, the park's tallest mountain at 4,345 m (14,256 ft) above sea level, rises 2,743 m (9,000 ft) above the nearby plain. More than 480 km (300 mi) of trails lead into remote alpine country. The park was named a Biosphere Reserve in 1976.

Geologic setting

The park's rocks and deposits record a history of nearly two billion years. The rocks at the core of its mountains are Precambrian — not the oldest in the National Park System, but from the era that holds Earth's oldest rocks, when its early crust and continents were forming. Longs Peak is a mass of Precambrian Silver Plume Granite, about 1.4 billion years old.

The Rockies were uplifted about 70 million years ago, in a mountain-building episode called the Laramide Orogeny. Isolated exposures of Mesozoic strata from the Western Interior Seaway survive along Laramide-age faults in the west of the park. Tertiary volcanism, 29 to 23 million years ago, formed many of the younger rocks on the park's western slope, including much of the Never Summer Mountains.

Geologic map of the park, from the Geologic Resources Inventory. NPS.

Abandoned mines

Abandoned mine sites can be important cultural resources and habitat, but many endanger visitors and wildlife and harm water, landscapes and other resources. Stay out and stay alive.

Maps and reports

The Geologic Resources Inventory makes digital geologic maps, reports, posters and scoping summaries for more than 270 natural resource parks; Rocky Mountain's are in the NPS DataStore, and a Soil Resources Inventory project for the park has been completed.

Lake fishing. Image from the NPS's page.

Sources

Based on "NPS Geodiversity Atlas—Rocky Mountain National Park, Colorado," National Park Service; a work of the United States government in the public domain. It cites KellerLynn (2004), Anderson (2017), Tweto (1987) and Braddock and Cole (1990). The source gives the park's peaks as 3,350 to 4,270 m (11,000 to 14,000 ft) high but Longs Peak as 4,345 m (14,256 ft); this page gives only Longs Peak's height.