Devil's Postpile

EFFORT Minimal
LENGTH1.0 to 5.0 miles
LOCATIONDevil's Postpile National Monument
CONTACT 760-934-2289
TRAILHEAD COORDINATES 37.37.896N, 119.05.125W

From June to September, you will have to take a shuttle bus to the postpile and pay a fee for the trip from 7:30 a.m. to 5:30 p.m. The bus runs every 20 minutes, starting at 8:00 a.m. The last ride back leaves Reds Meadow at 6:15 p.m. Buy tickets at Mammoth Mountain Inn, which is the departing point. If you come off-season or very early in the morning or in the evening, you can drive to the trailhead. Access is free.

Description: Located in Ansel Adams Wilderness, this national monument was established in 1911 to preserve the geological formation known as Devils Postpile, as well as the magnificent Rainbow Falls. Like many sites in the Sierras, the postpile exhibits a history of assault by the transforming forces of fire and ice.

The postpile is a remarkable basalt column formation about sixty feet high sitting at an elevation of 7,600 feet. The columns formed when basaltic lava erupted in the valley of the Middle Fork of the San Joaquin River about 100,000 years ago. The valley was filled with lava about 400 feet thick, which cooled at a uniform rate from both the top and bottom. As the lava cooled, it shrank and then cracked into these geometric shapes. The columns were exposed 10,000 years ago when a glacier flowed down this river gorge and scooped away one side of the postpile, revealing this splintered cliff face to the world. This is one of the finest examples of basalt columns you can see anywhere.

You will find the trailhead beside the ranger station. Pick up a park brochure there before setting out. It has a map which you may want to use to create your own hiking route, especially if you are taking advantage of the shuttle service and donít need to return to the same trailhead. We will be taking the most popular out and back trail to the postpile and continuing to the waterfall. If you only want to see the waterfall (impossible to imagine), there is a shorter hike (3 miles roundtrip) to it from a trailhead in Redís Meadow, just before the pack station on the right. If you are only going to the postpile and back, your hike will only be a mile.

The trail is wide and well-marked, and the way to the postpile is easy and level. Fortunately, most people can make the less than half mile trek to the postpile without difficulty. You will walk around a meadow blooming with wildflowers in summer. At a signed trail fork, go left for the postpile.

Other nearby evidence of recent volcanic activity includes Soda Springs on a gravel bar north of the postpile. Gases from deep in the earth combine with groundwater to produce carbonated mineralized springs. The iron in the water stains the gravel a rust color.

When you reach the postpile, walk along its base and marvel at the symmetry that nature exhibits. Each column has from three to seven sides, polygons that occur with some frequency in nature, from salt crystals on the floor of desert playas to mud cracks in a dry pond.

Those columns standing up straight are in place as they formed. Those on the edges which are bowed and angled towards vertical have moved over time. Amazingly, many of the bowed columns have not broken, as the movement occurs so slowly that the basalt has time to adapt and bend. At the bottom, lots of broken column pieces lie in a jumbled pile. Many good examples in this talus slope are immediately beside the trail, so you can get an intimate view of them. Take advantage of several split log benches to sit and admire the formation.

When you are ready, return to the left side of the postpile to take the steep uphill trail to the top. Once you are standing on the flat top of the columns, you will be amazed. It looks like a hexagonal tile floor, each "tile" highly polished and scratched by glaciers. The evidence of scraping ice is easy to read on this surface.

Look around the hill behind this floor and you will see more exposed sections of the basalt formation. You will also see a trail heading up, signed for Rainbow Falls. Take this trail even if you are not going to the waterfall. It circles the back of the postpile formation and comes around the other side back to the main trail. On the way, you will see more columns and the south side of the pile is quite interesting. Coming down on this loop, turn left to continue to the falls.

Walk south on the trail through lodgepole pine and red fir to Rainbow Falls on the Middle Fork of the San Joaquin River. Watch for the small Belding ground squirrel and Stellarís jays. The trail slopes gently downhill over its entire length. After about a mile from the start of your hike, you will cross a creek on a log bridge. The trail parallels the river bank, coming close enough in a couple of places to give you lovely views of the water and, in autumn, the yellow leaves of aspen and cottonwood. A lightning-sparked forest fire in 1992 burned out many of the trees along the trail. Their blackened trunks cover the hillsides. One memorable dead tree trunk stands beside the trail, its interior completely gutted by fire, leaving only a shell.

You will pass a trail junction where the left arm goes to Reds Meadows. Continue straight for the falls. Across the river are the volcanic formations known as the Buttresses, exposed basalt which is believed to be the oldest volcanic rock in the Monument area. This basalt is different from that of the postpile in that it has abundant pyroxene crystals.

Cross another plank bridge on the way over Boundary Creek. You will enter Ansel Adams Wilderness for a short while, and then cross back into monument land. At a junction with Fish Creek Trail, turn right and descend a dirt and log stairway. You will hear the tumult of the waterfall off to the right before you see it, and then you will reach the viewing area above the falls. It is an exquisite 101-foot drop over volcanic rock, which, in the right light, produces rainbows in its mist. When we were here, we saw a rainbow from the second viewing platform just above this first one.

The rock of the waterfall cliff is different from the basalt of the columns. That will be immediately apparent. This is andesite and rhyodacite, light gray and fine-grained, exhibiting horizontal thinly-spaced joints giving a platy appearance. Walk down to the second platform and take a look, and then continue to a long, steep flight of granite stairs down to the base of the falls where the continuous mist creates an inviting habitat for moss and ferns. Using the numerous rocks in the river, you can walk out on a gravel bar to a well-positioned tree trunk at the edge of the waterfallís emerald pool. This makes a perfect spot to sit and watch the falls, the spray gently raining down on you.

We were here in October when the volume of water is not at its height, but the waterfall was still running voluminous and magnificent. Along the right side of the main fall, the water skips down a natural stone staircase in a delicate descent to the river below.

You can continue another half mile to Lower Falls, if you are inclined to extend your trek. Otherwise, hike back the way you came. There is also an option of hiking back on another trail to Redís Meadow at the junction we passed on the way out, where the shuttle also stops. There is a store and restaurant there if you havenít packed a lunch. There is a hot spring near Reds Meadow, attesting to the continuing volcanic activity in the area. Allow extra time for the transportation to and from the trail if you are taking the shuttle. We ended up spending four hours here. There was a lot to see.

Driving Directions:Some of the roads traversing the Sierras are closed in winter, so check road conditions if you are coming in spring or fall. From U.S. 395, take the Mammoth Lakes exit and proceed to the Mammoth Mountain Inn (where a woolly mammoth statue stands beside the road). Proceed past Mammoth Mountain Inn and past Minaret Vista Point. Continue seven miles to an intersection and turn right, then another quarter mile to the parking lot.

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