Visiting Devils Postpile National Monument

Once a part of Yosemite National Park, Devils Postpile National Monument contains one of the most unusual rock formations in the country. A mix of vertical and horizontally warped hexagonal columns stand exposed along a ribbed cliffside. The columns—a product of thousands of years of volcanic activity—form a smooth, tilelike floor on top, while endless piles of broken columns lie scattered at its base. It’s a phenomenal site, and the nearby waterfall known as Rainbow Falls only adds to its never-ending allure. Saved by outdoorsman and environmentalist John Muir from demolition, Devils Postpile was designated as a national monument for its protection in 1911.

Devil's Post Pile

Photo by Adam Gulkis

The genesis of Devils Postpile dates back as far as eighty thousand to one hundred thousand years ago when a fissure vent poured basaltic lava into a valley north of the monument. This hot, molten lava kept flowing until it was blocked by a dam which in turn formed a “lava lake” that reached depths of four hundred feet. As this massive lake of lava cooled and solidified, it contracted, forcing joints to emerge and form in the shape of columns. Devils Postpile actually used to be much taller than it is today, but erosive forces—such as winds, rains, earthquakes, and freeze cycles—have knocked down the columns. Retreating glaciers have also wreaked havoc in the region during various Ice Ages and, in fact, are actually responsible for “excavating” the basaltic formations of Devils Postpile that would otherwise have remained hidden under volcanic remnants.

Moving to the other temperature extreme of geologic evolution, the impact of glacial pressure on the area during the Ice Age is evident with a hike to the top of the monument. There you can see a cross section of the polished tops of the columns, many bearing striations where glaciers scraped rocks across them during periods of contraction and expansion. These hexagonal tops are so smooth and well-preserved that you’d almost swear you were walking across a tiled floor. The columns average about two feet in diameter with the largest column measuring 3.5 feet across. Moreover, something that pictures can’t capture, many of the columns on the Devils Postpile soar as high as sixty feet in the air. Interestingly not all of the columns are hexagonal (six-sided). While most are, several others are five-sided while some others are seven-, four-, and three-sided. These variations in shape are due to the difference in cooling times for various areas of the basalt lava pool.


The glacier-polished, tile floor found atop Devils Postpile. Photo by Beverly Houwing. Find more at

The Devils Postpile environment is also home to a unique collection of flora and fauna. The national monument’s close proximity to the eastern slopes of the Sierra Mountains has allowed species from both sides of the mountain range to comingle. At the base of Devils Postpile, you’re likely to come across a variety of squirrels and chipmunks, as well as black bears which are also sighted in the area.


Photo by Adam Gulkis

As an interesting aside, not all black bears in this region hibernate during the winter, and the ones that do possess a rare and fascinating ability to recycle calcium back into their bones to prevent osteoporosis which can occur in other hibernating animals. Head to Soda Springs Meadow in the summer, and you’ll encounter a vast array of wildflowers and songbirds. Another unique feature of the environment is the burned forest area near Rainbow Falls which houses many plants and animals that do not typically inhabit heavily forested regions.

The best way to experience Devils Postpile is via the short hikes to the base of the postpile and then the hike to the top of the pile. It’s only a .4-mile walk to the base and just fifteen more minutes from that point to get atop the stacks. Another popular hike in the area is the one to Rainbow Falls, which is only 2.5 miles one way, and winds through a portion of the famous and beautifully panoramic Pacific Crest Trail, which stretches from the southern tip of California all the way to Canada.

Rainbow Falls

Photo by Bill Gracey

If you’re a little pressed for time, then you can look into shuttle bus options for getting to the falls which will knock off about two miles from your hike. In the summer season, the heat can make for a fairly moderate hike, so be sure to bring along plenty of water to keep yourself hydrated.

Visiting the monument area in the summer months usually requires a shuttle bus transport that departs from Mammoth Adventure Center and the Village at Mammoth. The only exceptions to this option involve those people with disabilities, as well as campers, vehicles arriving before 7 a.m. or after 7 p.m., and certain other scenarios. If you’re traveling during the fall, however, you can drive right up to the monument in your own vehicle, which is great for parents with children or for those just passing through and wanting to make a quick stop.

Cover Photo: Jerry Howells. Find more at

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