A series of deep fissures—the Great Rift—crossing the Snake River Plain in Idaho expelled vast acres of lava, cinder cones, spatter cones, lava tubes and nearly every variety of basaltic lava at Craters of the Moon National Monument and Preserve.
Established as a National Monument in 1924 by President Calvin Coolidge the protected area was expanded in 2000 to a total of 1,117 square miles.
Sixty distinct lave flows ranging in age from 15,000 to 2,000 years comprise the 618 square miles of the Craters of the Moon Lava Field. Further lava flows are expected by geologists in the future.
The Robert Limbert Visitor Center —just off Highway 20/26/93 18 miles southwest of Arco and 24 miles northeast of Carey, Idaho (90 miles from Twin Falls) — is open year-round with exhibits, films, bookstores, vending machines, drinking fountains and restrooms. A campground with limited amenities is nearby just inside the park.
A 7-mile loop road provides access to the Craters of the Moon including several volcanoes and numerous trails. A permit, available at the Visitor Center, is required to enter the caves and lava tubes.
Craters of the Moon photographs
Below several miniature volcanoes (spatter cones) mark a section of the Great Rift. View is south from Inferno Cone.
The Great Rift is a 52-mile-long fissure in Craters of the Moon National Monument and Preserve.
A brochure with information about Craters of the Moon, including photos of active volcanoes in Hawaii to illustrate how various features were formed, as well as a Loop Road map is included with your entrance fee.
North Crater Flow Trail
The first stop on the Craters of the Moon Loop Road is at the North Crater Flow Trail. North Crater (6244ft, 1903m) is on the left.
The North Crater Flow Trail crosses one of the most recent lava flows, about 2000 years ago, at Craters of the Moon.
The 0.3-mile North Crater Flow Trail extends to two monoliths that were rafted here by lava flows.
Devil’s Orchard Nature Trail
The second stop on the Loop Road is at Devil’s Orchard Nature Trail. All locations are well marked with signs detailing trail lengths, elevation gain, etc. The sign above explains how this trail got its name.
There are many more plants along the Devil’s Orchard Nature Trail than on the North Crater Flow Trail.
You have an opportunity to climb a cinder cone — Inferno Cone — at the next stop on the Loop Road.
Cinder cones are produced when lava with high gas content is erupted as foamy cinders that pile up near the vent.
The elevation gain on this 0.2-mile trail is just 164 feet to an elevation of 6181 ft, 1884m.
While relatively steep it is not nearly as high or steep as Cinder Cone at Lassen Volcanic National Park, for instance.
Unlike that cone, you won’t find the source of the cinders once you reach the top. These cinders were blown here by the wind.
You will have a nice view from the top of Inferno Cone. The picture at the top of the page looking toward the Spatter Cones on the Great Rift was taken here as was this photo looking south to Big Cinder Butte, one of the world’s largest basaltic cinder cones.
Spatter Cones are miniature volcanoes formed when blobs of molten lava were lobbed into the air, falling around the vent.
You can visit two spatter cones at the next stop on the Loop Road. The Snow Cone path is short and wheelchair-accessible.
Looking down into the crater of one spatter cone two small chipmunks had found a shady place to live.
Up close you can see how the blobs of lava stacked up and welded together to form the walls of the spatter cone,
similar to how a cinder cone grows but a different type of lava.
Lava Types at Craters of the Moon
Different types of lava are formed based on the magma temperature, viscosity, chemistry and mode of eruption.
The lava at Craters of the Moon is predominantly basaltic lava which is high in iron and magnesium.
When basaltic lava is erupted as large globs at relatively low velocity spatter cones like those above are formed.
With more velocity big globs of lava that travel further may harden in flight and form lava bombs such as these
near the base of the spatter cones. Lava bombs can take many shapes and are also expelled from cinder cone vents.
When more gas and velocity are involved in the eruption the lava cools to solid form in the air to produce
cinders which form into cinder cones around the vent or nearby mounds like Inferno cone.
The smallest lava chunks you’ll see at Craters of the Moon are cinders such as these at Inferno Cone.
The largest cinders in this picture are about 2" – 4" in diameter.
Low viscosity lava that flows smoothly is pahoehoe lava a Hawaiian term (pronounced “paw-hoey-hoey”) meaning “ropey”.
Sometimes pahoehoe lava will harden on the outside while still flowing on the inside.
If the flow stops and the lava inside flows out it will leave a lava tube such as those at stop
6 (Buffalo Caves)
and stop 7 (Dewdrop Cave, Boy Scout Cave, Beauty Cave and Boy Scout Cave) on the Loop Road.
Slower moving, more viscous lava that hardens in rough chunks pushed along by the flow behind
is called a’a lava another Hawaiian term (pronounced “ah-ah”) meaning “tough on feet” or “stony rough lava”.
Flora and fauna at Craters of the Moon
Lichen is growing on a block of lava near the North Crater Flow Trail in the above picture.
In early August when these photos were taken only a very few, dry looking flowers were growing.
Late May through mid-June — when snowmelt and occasional rains provide moisture — is the best time to view flowers.
Dwarf buckwheat plants and limber pines are some of the first larger plants to grow in the lava fields.
Kipukas (islands of vegetation surrounded by lava) and other sagebrush covered areas in the park are home to many plants and animals including sage grouse, pika, rabbit, prickly pear cactus, antelope bitterbrush and sagebrush.
Visit other National Parks and National Monuments in the US from my National Parks page.
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Website and all photos copyright © 2001–2016 Lee W. Nelson