Overview

Devils Postpile National Monument protects one of the highest concentrations of near-perfect hexagonal basalt columns in the world, and a striking showcase of how fire and ice shaped the Sierra Nevada. Roughly 90,000 years ago, a thick lava flow erupted from a vent above the Middle Fork of the San Joaquin River, pooling into a large lava lake. As it slowly cooled, it contracted into an orderly pattern of columns - most hexagonal, though not all. During the last Ice Age, glaciers sheared off the upper surface and polished the tops, revealing the geometric wonder seen today.

The area is accessible in summer months, and a mandatory shuttle offers visitors transportation to Devils Postpile and other Reds Meadow areas. Catch the shuttle from the Mammoth Adventure Center at Mammoth Mountain Main Lodge. Visiting Devils Postpile requires a one-mile roundtrip hike. The trail is not fully accessible to wheelchairs at this time.