The unique basalt columns of Devils Postpile National Monument are accessed after an easy, 1-mile there-and-back hike. An optional loop climbs the adjoining hillside for a look at the columns from above, and it adds an additional half mile.
While the Devils Postpile Trail is not ADA-accessible in its entirety, the first portion is well groomed and suitable for those with limited mobility. Continuing on to the top of the 60-foot formation requires navigating tree roots and steep stairs.
Around 100,000 years ago, a lava flow that was dammed by the terminal boulders of a glacial moraine began to cool under ideal circumstances. It was a combination of slow cooling and mineral consistency that formed one of the world’s most geometrically perfect examples of basalt columns.
A glacier that carved a path along the Middle Fork of the San Joaquin River was integral to unearthing the basalt formation. Around 80,000 years after the columns began forming, glacial ice planed the top of the hexagonal columns and exposed the face of the formation. Examples of this leveling can be seen can be seen from the trail at the top, and talus consisting of columns fractured during this event, ensuing erosion, and other seismic activity can be seen at the base of the formation.
The iconic basalt columns were nearly blasted to build a dam after the area’s exclusion from Yosemite National Park and its accompanying protections. Sierra Club members successfully lobbied President Taft to save the formation, and in 1911, Devils Postpile received National Monument status.
Nearby features include Reds Meadow and Rainbow Falls, and you'll also find trailheads for the Pacific Crest Trail and John Muir Trail. Campers and thru-hikers should use bear-proof containers when storing food.
In the busy summer months, a shuttle bus to Devils Postpile is required, and it departs from Mammoth Mountain ski area. In the off season, private vehicles are permitted to enter the valley. The road beyond Minaret Vista Station requires a fee and is closed in times of heavy snowfall.