How Volcanoes Helped Forge America’s Newest National Park

Tucked in the far southeastern corner of Arizona, surrounded by desert, are the remote Chiricahua (“cheer-a-cow-a”) Mountains, part of the Chiricahua Apache Nation’s traditional lands and now home to the nation’s newest national park. One of Arizona’s “sky islands,” the range slowly appears on the red horizon during the 120-mile drive east from Tucson. The most prominent peak soars a mile above the valley floor, a geologic North Star guiding visitors in.

Hidden in the green of the slopes surrounding the peak are countless rocky columns, weather-beaten and topped by precariously balanced rocks. “When you walk up to them, you don’t even notice them. It’s only when you stand back that you realize how big they are,” says Brian Gootee, Arizona’s state geologist. “They dominate your view.”

The sentinel spires jut skyward a hundred feet or more or lean against one another, worn by their long desert watch. Colloquially called hoodoos, pinnacles, or fairy chimneys, they’re the result of millions of years of Earth’s inner workings, wind, water, and time.

The pinnacles’ geologic story began with a dramatic volcanic eruption about 27 million years ago—relatively recent, from a geologist’s perspective.

A massive magma chamber had grown just a few miles under the Earth’s surface. When the chamber swelled and the rocks above could no longer restrain it, it erupted, spewing more than 100 cubic miles of lava which, along with ash and pumice, blanketed more than 1,200 square miles of the surrounding landscape. Pyroclastic flows of hot rock shards, thousand-degree ash and gases shot across the land at up to 100 miles per hour, destroying everything in their path.

“The eruption completely rewrote the story,” says Chad Kwiatkowski, a geologist with the Arizona Geological Survey. “It absolutely buried the landscape that was there before.”

The violent outburst left behind a caldera, known today as Chiricahua Peak, and the devastating pyroclastic flows filled a valley north of the new crater. As they cooled, they formed a thick layer of a volcanic rock called welded tuff.

Over the millions of years that followed, the valley’s walls eroded away, leaving the tuff exposed. The continent began stretching apart, and the Chiricahua Mountains rose over the desert. Water, ice, and wind worked on the welded tuffs, slowly carving out the columns and canyons we see today. Scientists think that because the rocks are so hard, this weathering process was very slow and that the columns are only about three million years old. They’ll likely tower for millions of years more. They’re in no rush.

The geologic pulling apart of the southwestern U.S. didn’t just shape the land. It shaped life there, too. The Chiricahua mountain range is one of the Southwest’s 40 or so sky islands, separated from each other by broad basins of red soil, arroyos, creosote, and sage.

Because of this separation, each range developed a delightfully distinctive array of flora and fauna. “If you go from one to another, you understand why they call them islands,” Gootee says. 

(Breathtaking ‘Sky Islands’ Showcase Evolution in Action.)

But isolation isn’t the only story here. For animals that can travel, such as cougars and birds, these islands act as connectors, stepping-stones to navigate between biomes. The Chiricahuas are a sort of biological four corners, sitting at the intersection of four major ecosystems: the Sonoran Desert to the west, the Chihuahuan Desert to the east, the high and dry Colorado Plateau to the north, and the neotropical Sierra Madre to the south. 

Because of that location, the Chiricahuas are home to everything from temperate animals such as black bears and coyotes to subtropical critters like the ever-inquisitive coati (a relative of the more pedestrian raccoon), ocelots, jaguars, and rare birds like elegant trogons and eared quetzals that can’t be heard anywhere else in the country. Riparian zones and caves host more than a dozen species of bat that prey upon the 6,500-plus insect species documented in the mountains. The range’s butterflies drew Vladimir Nabokov, an avid lepidopterist who also dabbled in literature, to visit in the 1950s. There are even massive turkeys roaming around, stopping traffic while visitors wait for them to amble across the road.

The Chiricahuas are also one of the largest sky islands, with an elevation change of about a mile from the valley floor to the summit. As you drive up, saguaro cacti and fragrant juniper give way to oaks and Arizona cypress; the highest reaches boast fluttering aspens and towering Douglas firs that give the pinnacles below a run for their money. “It’s like starting in Mexico and ending in Canada,” says Russ McSpadden, an environmental historian and conservation advocate with the Center for Biological Diversity in Tucson. 

Today’s visitors need not worry about the volcanic eruptions that shaped Chiricahua National Park. Although there is an active volcanic field to the southeast, the volcano that created the landscape is long extinct. Instead, monsoons and wildfires, which can send dangerous debris flows shooting into valleys, are the primary forces that shape the landscape—that, and humans.

Locals and conservationists like McSpadden have some concerns about increased visitor traffic, National Park Service funding cuts, and staffing shortages. Still, he’s happy to see stronger protection for the area.

“If more people are able to come and learn about sky islands, I think that’s incredible,” McSpadden says. He and others in conservation would like to see more sky islands protected in the future, treated as the ecological network that scientists see. 

“We tend to think about the sky islands as a whole,” he says. Several in Mexico are already protected as wildlife sanctuaries. “This, we hope, is just our first.”