Mammoth Crater, Tulelake, Ca

Mammoth Crater with a ranger
Mammoth Crater with a ranger

NPS Photo by Ranger Brian

Between thirty and forty thousand years ago, through a series of eruptions, a torrent of red-hot lava flowed out of this crater. More than any other vent Mammoth Crater had the greatest impact on the monument’s landscape—over seventy percent of the surface area of Lava Beds is covered by basalt that originated here. From this crater, lava ran downhill, forming braided streams of lava up to ten miles long. These lava streams later formed most of the caves along Cave Loop Road.

The remarkable amount of lava that poured from the earth here created the highest known concentration of lava tube caves in the continental United States. To learn more, visit Mushpot Cave near the Visitor Center.

A short trail meanders along the rim of Hidden Valley under Ponderosa pines. Enjoy the rare shade this area provides in summertime, and observe the impressive results of lava that flowed through from Mammoth Crater. The short trail to Mammoth Crater begins across the road at the parking area and leads up to the rim. Imagine lava flowing in multiple episodes from this massive crater about 30,000 years ago. It created all the lava tube caves in the Cave Loop area, and many more farther north. To explore the rocky, forested landscape of Lava Beds’ southern end further, continue around the Big Nasty Trail or hike the nearby trail to Heppe Cave.

Lava Beds National Monument

Last updated: November 6, 2021