These columns of basalt at the Devils Postpile were
formed by cooling lava more than 100,000 years ago.
Sixty-foot columns of basalt rise like organ pipes above pine forests on the western slopes of the Sierra Nevada Mountains in California. Devils Postpile National Monument was established in 1911 to preserve these volcanic remains, as well as 101-foot-high Rainbow Falls.
Some 100,000 years ago, basalt lava flowed from a volcanic vent in the valley of the Middle Fork of the San Joaquin River, filling the valley near the postpile to a depth of 400 feet. As the lava cooled, it shrank and cracked, forming a vertical pattern on the surfaces of the flow. The cracks deepened to form long post-like columns two to three feet in diameter with three to seven sides.
Perhaps 10,000 years ago, a glacier moved down the Middle Fork and over the cracked lava flows, exposing one side of the postpile and polishing its top. Visitors can hike to the top of the postpile to see the cross-section of columns, which looks somewhat like a tiled floor. Though Devils Postpile is not the only example of columnar-jointed basalt, it is one of the finest.
Many hiking trails cross the monument's nearly 800 acres of lodgepole pine and red fir forests, which are home to wildlife ranging from bears to ground squirrels. Loop trails lead to and from the postpile and Rainbow Falls, where the San Joaquin River drops more than 100 feet over a sheer cliff of ancient lava flows. A stairway and short trail lead to the bottom of the falls. Longer trails lead south of the falls and west on King Creek Trail. At the northern tip of the monument, the John Muir and Pacific Crest trails join and continue through the site. The 211-mile John Muir Trail, named for the famous conservationist and champion of Yosemite, connects Yosemite National Park to Kings Canyon and Sequoia national parks.
The Devils Postpile region is still a volcanically active area, as the nearby Soda Springs attest. The mineral springs, which lie on a gravel bar along the San Joaquin River north of the postpile, were created when pressure inside the earth drove hot gases upward, where they mixed with ground water. The gravel around the springs is stained red from iron in the water, which oxidizes when exposed to air.
Devils Postpile National Monument Information
Address: From U.S. Highway 395: 10 miles west on S.R. 203 to Minaret Vista and another 8 miles on a paved, steep mountain road
Hours of Operation: Open during the summer season; opening and closing dates set each year
Admission: adults, $7; children under 16, $4
Learn about these other national monuments:
To learn more about national national monuments, memorials, and historic sites, and other travel destinations in North America, visit:
- National Monuments: Learn more about America's national monuments.
- National Memorials: Discover national memorials in the U.S.
- National Historic Sites: Read about American national historic sites.
- California State Guide: Learn about Mobil Travel Guide-rated hotels and restaurants in California as well as other recreational activities.
ABOUT THE AUTHOR:
Eric Peterson is a Denver-based freelance writer who has contributed to numerous guidebooks about the Western United States.