The columns at Devils Postpile are considered some of the finest examples of columnar basalt in the world due to their uniform length and symmetry.
The basalt columns were only exposed after a glacial glacier smoothed the top of the lava flow, leaving behind the 'postpile' formation.
The formation was designated a national monument in 1911 by President William Howard Taft to protect it from being destroyed during plans to dam the San Joaquin River.
The columns were formed from a dense, iron-rich lava that reached a thickness of 400 feet before cooling.
Rainbow Falls, located within the monument, is named for the frequent rainbows visible in its mist during the summer months.
The monument is located within the Ansel Adams Wilderness area, bordering the Inyo National Forest.
Devils Postpile National Monument features a rare geologic formation of basalt columns created by volcanic activity roughly 82,000 years ago. The columns reach heights of up to 60 feet and exhibit hexagonal, pentagonal, or quadrilateral cross-sections. This site is located within the Eastern Sierra Nevada mountains at an elevation of approximately 7,560 feet. Beyond the rock formation, the monument includes the 101-foot tall Rainbow Falls, fed by the Middle Fork of the San Joaquin River. The landscape was shaped by glacial action, which exposed the columns by stripping away surrounding rock. Visitors can access the area via the John Muir Trail and Pacific Crest Trail, which intersect within the monument. The monument encompasses 800 acres of protected federal land managed by the National Park Service. Geologically, the formation resulted from a basaltic lava flow that cooled and contracted in a process known as columnar jointing.
The base of the columns for a perspective of their height, or the viewpoint overlooking Rainbow Falls.
Wear sturdy, broken-in hiking boots to navigate the uneven volcanic rock and forest trails.
Carry plenty of water and sun protection, as the high elevation significantly increases UV exposure.
Check local air quality reports before visiting, as wildfire smoke in the Sierra Nevada can frequently impact visibility and air safety during summer.
Attempting to visit during winter or spring, as the access road is buried under heavy snow and remains closed.
The monument and its access road are closed to vehicle traffic during the winter and spring due to heavy snowfall, typically opening in mid-to-late June.
Stay on marked trails to protect fragile alpine vegetation and avoid climbing on the basalt columns, which is prohibited to prevent erosion.
