Monday, December 5, 2022


Hell’s Half Acre Lava Field off I-15 in Idaho

Hell’s Half Acre Lava Field trail at North Blackfoot Rest Area on I-15. (Julianne G. Crane)

We were steaming south along I-15 from Butte heading toward Salt Lake City, when we pulled into the rest area at mile post 101 north of Blackfoot, Idaho. At first I barely noticed that the rest stop was surrounded by an amazing rugged landscape until I looked up and spotted a ridge of dark volcanic rock.

Lava bowl. (Julianne G. Crane)

It seems this particular I-15 rest area sits in the southeast corner of “Hell’s Half Acre Lava Field.”

As a result, in addition to a typical rest area’s large grassy expanse, covered picnic tables and a pet exercise area, there is an easy access paved path into ancient lava formations. The walking trail is complete with places to sit and information signs about the site’s history, vegetation and resident wildlife.

Close up of lava flow.

The name of the lava field–Hell’s Half Acre--was given to it by “fur traders in the early 19th century seeking passage through the rough terrain of the Rocky Mountains. The term ‘hell’s half acre’ was a commonly used expression to describe any rough land,” reported one source.

The Idaho Historical Marker “Lava Formations” states: “Molten rock, forced upward from 30 to 50 miles through fissures in the earth had cooled into the hard lava found here.”

“Continued pressure from below has made great cracks in the contorted surface. This lava solidified only a few thousand years ago, and not very much soil covers it yet. But vegetation is getting a start, and unless new flows intervene, windblown soils will cover these rock layers. Then the surface here will look the same as the surrounding plains, which also are layers of lava and windblown soil.”

It is said that each year more than 100,000 people explore the rest area’s trails.

Craters of Moon National Monument 

Lava Flow Campground (NPS)

For those who want to see more of this mysterious landscape, the Craters of Moon National Monument is about 90-miles west from Idaho Falls or Blackfoot on Highway 20/26/93.

There is a 51-site campground among the lava formations beyond the visitor center. “Campsites are $10 per night per campsite ($6 per campsite in the early and late season when no water is available). First-come first-served, self register.” (Senior Pass provides a 50-percent discount.)

There are a number of trails in the national monument, some with easy access for day hikes and wheelchairs.
However, be aware and stay on the trails — two hikers when missing on Sept. 19, 2013, and both died from exposure within a couple days. They were discovered less than a mile of the trail. 

To read more writing about the RV lifestyle by Julianne G. Crane, go to

Top three photos: (Julianne G. Crane) Bottom: National Park Service.

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