Devils Postpile National Monument — rock formation
Frank Kovalchek from Anchorage, Alaska, USA · CC BY 2.0

Devils Postpile National Monument

  • 2 min read
  • 37.624° N 119.084° W

Interesting facts

  • The cooled lava that became the Postpile is estimated to have been 400 to 600 ft thick, and the columns formed near its base.
  • In a survey of 400 columns, 44.5 percent were six-sided, a higher share of hexagons than at most other columnar basalt sites.
  • Unlike many columnar formations, the Postpile has almost no horizontal joints cutting across its columns.
  • The thickest column measures about 3.5 ft (1.1 m) across, while most range from 10 to 30 inches.
  • The monument was proclaimed in 1911 as Devil Postpile, with no s; the plural form without an apostrophe has been official since the 1930s.
  • An older local name was the Devil's Woodpile, credited to sheepherders who saw the devil's hand in any strange landform.
  • The lava is thought to have flowed from near Upper Soda Springs, at the north end of Pumice Flat on the valley floor.
  • Except for a small developed area around the headquarters, the whole monument lies within the Ansel Adams Wilderness.

Why it is worth it

High in the Sierra Nevada, on the Middle Fork of the San Joaquin River, a wall of grey stone columns rises like a giant's stack of fence posts. Devils Postpile is one of the finest exposures of columnar basalt in the world: a lava flow that cooled less than 100,000 years ago and cracked, as it shrank, into tall, near-regular prisms. The columns reach up to about 60 feet (18 m) in length, average around two feet across, and are remarkably geometric — almost half are six-sided, more than a third five-sided, with a scattering of four-, seven- and even three-sided forms.

The story did not end with cooling. Later, a glacier moved over the formation and planed off the tops of the columns, leaving a surface on the crest that looks almost like a tiled floor, still marked with the scratches the ice dragged across it. At the foot of the wall lies a long apron of broken columns that have toppled over the millennia. Downstream, the river drops 101 feet (31 m) over Rainbow Falls, named for the bows of colour that appear in its spray on sunny days. The John Muir Trail and the Pacific Crest Trail run together through the monument, which sits between 7,200 and 8,200 feet above sea level and borders the Ansel Adams Wilderness.

The site was once part of Yosemite National Park, but was cut out of the park after gold was found near Mammoth Lakes in 1905. A plan followed to blast the columns into rubble for a hydroelectric dam on the river; John Muir and others campaigned against it, and on 6 July 1911 President William Howard Taft proclaimed the area a national monument. Today it covers just under 800 acres — a small reserve built around a single, extraordinary piece of geology.

Getting there

Devils Postpile lies on the western side of the Sierra crest, and the practical approach is from the east. From US Highway 395, State Route 203 climbs about 10 miles (16 km) west through the town of Mammoth Lakes to Minaret Vista, followed by roughly 8 miles (13 km) of steep, partly single-lane mountain road down to the monument. The nearest airport is Mammoth Yosemite Airport (MMH), about 21 km away in a straight line. The city of Clovis, around 104 km to the southwest, is on the far side of the mountains with no direct road across.

On these lists

The Most Beautiful Places in California 36The Most Beautiful Places in the United States 228The Most Remarkable Rock Formations in the United States 18The Most Beautiful Natural Wonders in the United States 68The Most Remarkable Rock Formations 107The Most Beautiful Natural Wonders 580

From the encyclopaedia

Devils Postpile National Monument is a U.S. national monument located near Mammoth Mountain in Eastern California. The monument protects Devils Postpile, an unusual rock formation of columnar basalt, "all closely and perfectly fitted together like a vast mosaic", and Rainbow Falls a waterfall on the Middle Fork of the San Joaquin River, which are also the two main attractions. The monument encompasses 798 acres (323 ha). 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.

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37.62440, -119.08400per Wikidata