Some 27 million years ago, a volcano in what’s now southeastern Arizona unleashed a spectacular series of eruptions, strewing more than 1,000 times as much volcanic material across the landscape as Mount St. Helens did in 1980.
The explosive eruptions blanketed the region, part of the Chiricahua Apache Nation’s traditional lands, with ash and pumice. Layered into this were massive pyroclastic flows that hardened into deposits of welded rhyolitic tuff that in some areas were nearly 1,600 feet (500 meters) thick, about three times the height of the Washington Monument. As the magma chamber emptied, the ground above it collapsed, leaving a gaping depression—the Turkey Creek caldera—that was roughly 12 miles (19 kilometers) wide and 4,900 feet (1,500 meters) deep.
An array of geologic processes, including erosion and weathering, gradually sculpted the welded layer of tuff into the collection of dramatic spires, hoodoos, and canyons that visitors to the caldera area encounter today.
The Apache called the area “The Land of the Standing-Up Rocks” for good reason. Hiking through Rhyolite Canyon or driving through Bonita Canyon means encountering a dizzying maze of rock pinnacles, some hundreds of feet tall. Others, like Big Balanced Rock, have surprisingly large boulders precariously perched on top. Meanwhile, those at Heart of Rocks and Massai Point are gathered into groups of hundreds.
The area was designated a national monument in 1924 to preserve its remarkable geology. In October 2026, it was redesignated as Chiricahua National Park (pronounced cheery-cow-ah). The OLI (Operational Land Imager) on Landsat 9 captured this cloud-free image of the new national park on July 2, 2026.
Individual rock spires are too small to distinguish, but the eroding rhyolitic tuff landscape appears gray. Stream valleys dense with trees and other vegetation, including Rhyolite Canyon and Bonita Canyon, snake across the landscape. With four biogeographic regions converging in the park—the Sonoran Desert, the Chihuahuan Desert, the Rocky Mountains, and the Sierra Madre—it is a haven of plant diversity.
Among the 1,000 species growing within the park’s varied desert, grassland, chaparral, deciduous forest, and coniferous forest ecosystems are agaves, prickly pear cacti, yuccas, manzanita, pine, fir, cypress, sycamore, juniper, and oak. The park’s location within the Chiricahua Mountains puts it among several “sky islands” in Arizona—isolated mountain ranges that emerge from the surrounding desert “sea.” According to the National Park Service, the range’s highest point (outside the park) rises 2,986 meters (9,795 feet) above sea level, more than 1,800 meters above the surrounding valley.
NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Story by Adam Voiland.
- The Conversation (2026, October 21) Chiricahua is the nation’s newest national park – what does that mean? Accessed October 27, 2026.
- National Geographic (2026, October 26) How Volcanoes Helped Forge America’s Newest National Park. Accessed October 27, 2026.
- National Park Service (2026) NPS Geodiversity Atlas—Chiricahua National Monument, Arizona. Accessed October 27, 2026.
- National Park Service (2026) Chiricahua National Park. Accessed October 27, 2026.
- National Park Service (2026) Geologic Formations. Accessed October 27, 2026.
- Smithsonian Magazine (2026, October 22) Arizona’s Otherworldly ‘Wonderland of Rocks’ Is Now America’s Newest National Park. Accessed October 27, 2026.
- U.S. Department of the Interior (2026, October 21) Chiricahua National Monument Becomes America’s Newest National Park. Accessed October 27, 2026.
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