Established in 1911 by presidential proclamation, Devils Postpile National Monument protects and preserves the Devils Postpile formation, the 101-foot high Rainbow Falls, and pristine mountain scenery. The formation is a rare sight in the geologic world and ranks as one of the world’s finest examples of columnar basalt. Its columns tower 60 feet high and display an unusual symmetry.
It was created in 1911 as Devil Postpile National Monument, and has forever been widely referred to as Devils Postpile National Monument; but it has been officially styled as plural without the apostrophe since the 1930s. The monument was once part of Yosemite National Park, but discovery of gold in 1905 near Mammoth Lakes prompted a boundary change that left the Postpile on adjacent public land. Later, a proposal to build a hydroelectric dam called for blasting the Postpile into the river. Influential Californians, including John Muir, persuaded the federal government to stop the demolition and, in 1911, President William Howard Taftprotected the area as a National Monument.
The name “Devils Postpile” refers to a dark cliff of columnar basalt. Radiometric dating indicates the formation was created by a lava flow at some time less than 100,000 years ago. The source of the lava is thought to have been somewhere near Upper Soda Springs campground at the north end of Pumice Flat on the floor of the Middle Fork of the San Joaquin River, from where it flowed to the site of the Postpile. Estimates of the formations thickness range from 400 feet to 600 feet. The lava that now makes up the Postpile was near the bottom of this mass.