NPS Geodiversity Atlas—Mount Rainier National Park, Washington

Geodiversity refers to the full variety of natural geologic (rocks, minerals, sediments, fossils, landforms, and physical processes) and soil resources and processes that occur in the park. A product of the Geologic Resources Inventory, the NPS Geodiversity Atlas delivers information in support of education, Geoconservation, and integrated management of living (biotic) and non-living (abiotic) components of the ecosystem.

image of mount rainier gri report cover with landscape image
In-depth geologic information is contained in the baseline inventory products of the Geologic Resources Inventory, see table below.

Geologic Features and Processes

[Site Under Development]

Glacial Resources

The glaciers of Mount Rainier form the largest glacier system in the conterminous United States and are an important source of streamflow for several rivers. Some of the glaciers originate from the summit of the volcano, while others extend down the mountain flanks from cirques located in a high- precipitation zone at middle elevations. Some features associated with the erosional process of glaciers include horns, cirques, glacial valleys (U-shaped valleys), moraines, and arêtes (rugged linear crests or ridges between two mountains, locally known as cleavers). The Willis Wall is the 3,600- foot- high (1,100 m) vertical headwall that marks the Carbon Glacier cirque.

The most "iconic" glaciers at Mount Rainier include the Emmons (largest glacier in the contiguous United States), Cowlitz-Ingraham, Paradise, Nisqually, Tahoma, Carbon, Kautz, and Winthrop.

Paleontological Resources

Documented fossils at Mount Rainier are from the following formations: Ohanapecosh Formation (late Eocene-Oligocene), Stevens Ridge Formation (Oligocene-Miocene), mass wasting deposits (Holocene), and modern pollen and lacustrine deposits (Holocene).

All NPS fossil resources are protected under the Paleontological Resources Preservation Act of 2009 (Public Law 111-11, Title VI, Subtitle D; 16 U.S.C. §§ 470aaa - 470aaa-11).

Cave and Karst

Mount Rainier contains large volcanic-ice caves. The ice caves, and fumaroles, near the summit of the volcano are formed as a result of hydrothermal reactions between groundwater and rising gas steam from the underlying magmatic system. Glacial meltwater, rather than hydrothermal processes, also form some of the caves at the park. There are at least five caves in the park, however, these caves are constantly changing, and may be unstable and hazardous. Volcanic gases enriched with carbon dioxide can pose a threat to explorers who enter the summit ice caves.

All NPS cave resources are protected under the the Federal Cave Resources Protection Act of 1988 (FCRPA)(16 U.S.C. § 4301 et seq.).


Cryptobiotic soil crusts are essential to the high-elevation ecosystems and assist in increasing soil stability by binding soil particles together. These soils increase infiltration and enhance nutrient and water availability to aide in the growth of vascular plants.

Solid rock and talus slopes with virtually no topsoil occupy the higher elevations of Mount Rainier, while lower elevations are composed of glacial till. Valley bottoms contain layers of mixed rocks and benches of silt deposited by streams and glaciers. Subalpine meadows have very shallow, loose, friable soils that are easily eroded by foot and horse traffic.


Active geologic processes continue to shape the park everyday. Volcanic and non-volcanic forces can threaten visitor safety and damage park infrastructure.

Mount Rainier is considered to be one of the most seismically active volcanoes in the Cascade Range. In a given month, an average of 1- 2 high-frequency volcano-tectonic earthquakes occurs directly beneath the summit (Moran and Malone, 2000). A strong enough earthquake could trigger edifice collapse, avalanches, debris flow, and rockfalls.

Volcanic related geohazards include volcanic ash, volcanic projectiles, pyroclastic flows and surges, volcanic gases, lava flows, and lateral blasts. The generation of lahars, volcanic flows, and debris flows from an eruption could cause major destruction to the Seattle-Tacoma lowland drainages. The most destructive volcanic related hazard at Mount Rainier include: lahars, as their high speed and magnitude pose a threat to life and property.

During dormant periods unstable rock walls can become weakened resulting in snow and debris avalanches, rockfalls, and landslides. Seasonal and daily temperature changes cause freequent rockfall on the upper mountain and other steep slopes within the park.

Flooding at Mount Rainier occurs year-round, but the potential for floods increases in the summer months when the snow and ice melts. Flooding can also be triggered by precipitation, volcanic activity, and glacial outbursts.

Abandoned Mineral Lands

Abandoned mine features in the park include adits, shafts, surface quarries, prospects, waste rock piles, related equipment, cabin and other building remains, and access roads.

NPS AML sites can be important cultural resources and habitat, but many pose risks to park visitors and wildlife, and degrade water quality, park landscapes, and physical and biological resources. Be safe near AML sites—Stay Out and Stay Alive!

Geology Field Notes

Students and teachers of college-level (or AP) introductory geology or earth science teaching courses will find that each park's Geologic Resource Inventory report includes the Geologic History, Geologic Setting, and Geologic Features & Processes for the park which provides a useful summary of their overall geologic story. See Maps and Reports, below.

Regional Geology

Mount Rainier is a part of the Cascade-Sierra Mountains Physiographic Province and shares its geologic history and some characteristic geologic formations with a region that extends well beyond park boundaries.

Maps and Reports

The Geologic Resources Inventory produces digital geologic maps and reports for more than 270 natural resource parks. The products listed below are currently available for this park, check back often for updates as many maps, reports, and posters are still in progress.
  • Scoping summaries are records of scoping meetings where NPS staff and local geologists determined the park’s geologic mapping plan and what content should be included in the report.
  • Digital geologic maps include files for viewing in GIS software, a guide to using the data, and a document with ancillary map information. Newer products also include data viewable in Google Earth and online map services.
  • Reports use the maps to discuss the park’s setting and significance, notable geologic features and processes, geologic resource management issues, and geologic history.
  • Posters are a static view of the GIS data in PDF format. Newer posters include aerial imagery or shaded relief and other park information. They are also included with the reports.
  • Projects list basic information about the program and all products available for a park.

Source: Data Store Saved Search 3022. To search for additional information, visit the Data Store.

NPS Soil Resources Inventory project has been started for Mount Rainier National Park and can be found on the NPS Data Store.

Source: Data Store Saved Search 3069. To search for additional information, visit the Data Store.

Related Articles

Mount Rainier National Park

National Park Service Geodiversity Atlas

The servicewide Geodiversity Atlas provides information on geoheritage and geodiversity resources and values within the National Park System. This information supports science-based geoconservation and interpretation in the NPS, as well as STEM education in schools, museums, and field camps. The NPS Geologic Resources Division and many parks work with National and International geoconservation communities to ensure that NPS abiotic resources are managed using the highest standards and best practices available.

For more information on the NPS Geodiversity Atlas, contact us.

Part of a series of articles titled National Park Service Geodiversity Atlas.

Mount Rainier National Park

Last updated: February 10, 2022