<Tr> <Th> Governing body </Th> <Td> National Park Service </Td> </Tr> <Tr> <Th> Website </Th> <Td> Devils Postpile National Monument </Td> </Tr> <P> Devils Postpile National Monument is located near Mammoth Mountain in eastern California . The national monument protects Devils Postpile, an unusual rock formation of columnar basalt . Devils Postpile National Monument encompasses 798 acres (323 ha) and includes two main tourist attractions: the Devils Postpile formation and Rainbow Falls, a waterfall on the Middle Fork of the San Joaquin River . In addition, the John Muir Trail and Pacific Crest Trail merge into one trail as they pass through the monument . Excluding a small developed area containing the monument headquarters, visitor center and a campground; the National Monument lies within the borders of the Ansel Adams Wilderness . </P> <P> 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 Taft protected the area as a National Monument . </P>

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