Devils Postpile National Monument

In the Devils Postpile National Monument, located high on the western slope of the Sierra Crest, nature reveals two of its wonders the weirdly wonderful “postpile” and the lovely San Joaquin River with its dramatic Rainbow Falls. The geologic formation that is “the Postpile” is the world’s finest example of unusual columnar basalt. Its columns of lava, with their four to seven sides, display a honeycomb pattern of order and harmony.

Another jewel in the Monument is the San Joaquin River. Along the river corridor, the Monument flourishes with life. Meadows burst forth with flowers that nourish deer, birds and butterflies. Lining the river are a combination of old-growth red-fir forest and new growth rejuvenated by fire. On the lower reaches of the Monument’s 2.5 miles of river course, rainbows frequently sparkle over their namesake – the 101 foot drop of Rainbow Falls.

In addition to its geologic wonders and the beauty and diversity of the San Joaquin River, the monument is a portal to the great Sierra backcountry. Some 75% of the monument is part of the Ansel Adams Wilderness. It is traversed by the John Muir and Pacific Crest trails; you can follow a trail from here to Mexico or Canada.

At 800 acres, Devils Postpile National Monument may be considered small by some, yet its natural and recreational values abound.

Nature & Science

The “postpile” is a fascinating geologic formation. The process of its creation began almost 100,000 years ago, when molten basalt lava flowed from the earth one mile upstream from the modern-day monument. Imagine a mass of lava 400 feet deep flowing like a river for three miles. As the lava slowly cooled from the outside toward the middle of the flow, ideal conditions caused the lava to crack into long post-like columns. Look at the surface of the mud in a dried-out puddle and you may see similar polygonal shapes.

During the last major ice age, which ended about 10,000 years ago, a glacier sculpted away the top layers of lava. It revealed the internal fractured lava mass and exposed a wall of columns 40 to 60 feet high. Some say it resembles a giant pipe organ. Our 140,000 visitors per year each find their own metaphor to describe it, but all of them call it “fascinating!”

Getting There

From the East
Drive 10 miles west from U. S. 395 on S. R. 203 to Minaret Summit & then 7 miles on a paved, narrow mountain road. Most visitors must park at Mammoth Mountain & use the shuttle.

By Public Transporation
From late June to early September, day-use visitors to the Devils Postpile/Reds Meadow area must ride the shuttle bus.

Traveler Facts

Contact Information
Devils Postpile National Monument
P. O. 501 Box
Mammoth Lakes, CA 93546
Phone: 760-934-2289 (Summer)

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