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Craters of the Moon National Monument

Craters of the Moon area in Idaho. Duane Reynolds, Idaho Bureau of Land Management.
Craters of the Moon area in Idaho. Duane Reynolds, Idaho Bureau of Land Management.
Established: 1928, plus several later expansions (including a significant one in 2000) have resulted in today's 715,000 acre Monument that is co-managed by the National Park Service and the Bureau of Land Management.
Location: Central and southern Idaho, bounded by the Yellowstone Plateau on the east and the Oregon state line on the west.
Size: 715,000 acres

Special Features

Craters of the Moon National Monument is an unearthly landscape and a topographical wonder. Cinder cones, lava tubes, deep cracks and vast lava fields form a volcanic sea on central Idaho's Snake River Plain, all centered around The Great Rift, a 62 mile long crack in the earth's crust.


Illegal cross-country off-road vehicle use damages fragile soils and volcanic features and disturbs wildlife. Visitors intentionally and unintentionally damage the delicate cinder gardens and cones and accelerate erosion when they stray off trails and walk or rock climb in sensitive areas with fragile volcanic features.

More about the Monument

"The strangest 75 square miles on the North American Continent" is how early American explorers described Craters of the Moon. No doubt they had encountered the Monument's three major lava fields, which cover almost half a million acres. The Monument also includes 250,000 acres of sagebrush steppe grasslands. Foothills of the Pioneer Mountains in the north give way to the low relief of the lava flows in the rest of the Monument.

Volcanic eruptions first occurred at Craters of the Moon about 15,000 years ago. The most recent eruptions ended about 2,100 years ago and were likely witnessed by the Shoshone people. A Shoshone legend speaks of a serpent on a mountain who, angered by lightning, coiled around and squeezed the mountain until liquid rock flowed, fire shot from cracks, and the mountain exploded. Note 1

When expanding gases in the lava ejected bubbly rocks hundreds of feet into the air, cinders showered the ground to form cones. Less explosive lava flowed in sheets and rivers. The result: a basaltic lava field with more than 25 volcanic cones, some of which, like Big Cinder Butte, tower more than 700 feet above the surrounding plain.

The eruptions also created lava tubes where lava cut deep channels and then hardened. These lava caves are lined with "curbs"--ridges formed where the draining lava temporarily held at a constant level. Some caves also harbor lava stalactites, mineral deposits and ice and water stalactites. Where enough sunlight filters into caves, lichen and mosses grow on the cave walls.

Despite the moonscape appearance of some of the Monument, the area that is sagebrush grassland steppe in particular harbors diverse plants, wildflowers, animals, and birds. Even the lava fields support diverse life. For example, where lava flowed around areas of higher ground, there are today isolated islands of vegetation called "kipukas." Those kipukas harbor some of the last pristine vegetation in the Snake River Plain, including 700-year-old juniper trees and relic stands of sagebrush and native bunchgrass. The caves, too, provide habitat for bats, and swallows, bluebirds and great horned owls swoop around the rocky ledges of cave entrances.

History and Future of Craters of the Moon

President Coolidge established the Monument in 1928 as part of the National Park System. Since then, the Monument has been expanded five times, including a significant expansion on November 9, 2000 by President Clinton, that brought about 270,000 acres of Bureau of Land Management lands into the Monument and expanded its total acreage to about 715,000 acres of federal land.

Today, the Monument is co-managed by the National Park Service and the Bureau of Land Management, each with responsibilities for separate portions of the area. These two agencies are jointly preparing a new Resource Management Plan (RMP) to address the needs of the expanded area for the next 15 to 20 years. The draft RMP was released in early 2004; the public comment deadline is July 28, 2004. For the current status of planning and opportunities to give your opinion on how to manage and protect this area, see the BLM's Idaho planning site and stay tuned for alerts on this web site.

Note 1 USGS web page.


The BLM Action Center
BLM's Idaho office
National Park Service
The Wilderness Society-Idaho office: 208-343-8153

Updated June 2004