Craters of the Moon

Apollo astronauts trained here in 1969; the youngest flows are 2,000 years old

Craters of the Moon spreads across the Snake River Plain in central Idaho between Arco and Carey, at about 5,900 feet. Its central feature is the Great Rift, a crack in the Earth's crust some 52 miles long, and three major lava fields lie along it. Among the open rift cracks is the deepest known on Earth, at 800 feet. The Craters of the Moon Lava Field alone covers 618 square miles, the largest mostly Holocene basalt field in the contiguous United States, made of 60 distinct flows from 15,000 to just 2,000 years old, with more than 25 volcanic cones, fine spatter cones, lava tubes and tree molds left by trees the lava burned. The most recent eruptions ended about 2,100 years ago, and the BLM expects activity to continue.

Rain soaks straight into the basalt cracks, reappearing far off in springs in the walls of the Snake River Canyon, so the young flows carry only a sparse, seasonal cover of plants and look from a distance like black desolation. The Northern Shoshone crossed the lava on summer trails from the Snake River to the camas prairie, and built the stone circles near Indian Tunnel. They likely witnessed the last eruptions; Ella E. Clark recorded a Shoshone story of a serpent who, angered by lightning, coiled around a mountain and squeezed until liquid rock flowed, fire shot from the cracks and the mountain exploded. In the 1850s and 1860s Oregon Trail wagons skirted the flows on Goodale's Cutoff, which followed those trails.

The Boise taxidermist, photographer and filmmaker Robert Limbert explored and mapped the area in the early 1920s, the geologist Harold T. Stearns coined the name in 1923, and on 2 May 1924 President Calvin Coolidge proclaimed the monument to preserve its weird and scenic landscape. The Apollo astronauts Alan Shepard, Edgar Mitchell, Eugene Cernan and Joe Engle trained here, learning to find and collect good rock specimens in a harsh, unfamiliar place, though the Moon turned out not to look much like it: its craters come from impacts, these from eruptions.

In 2000 a presidential proclamation expanded the monument 13-fold to take in the whole Great Rift, and in 2002 the Park Service lava lands became a national preserve, where hunting is allowed. The National Park Service and the Bureau of Land Management now share the management. The monument became an International Dark Sky Park in 2017, and a 7-mile loop road leads to many of the features.