El Pinacate | Schuk Toak & Gran Desierto De Altar

An Introduction to the Human Ecology of the Black Volcanic Heart

of the Sacred Sonoran Desert

A.R.Berman 2023-24

(See Sources Below)

El Pinacate y Gran Desierto de Altar, or just ‘El Pinacate’ for short, is a federally protected Biosphere Reserve, a UNESCO World Heritage Site, and a relatively undisturbed natural environment located just thirty miles from the US-Mexico Border in Mexico’s northernmost state of Sonora. It is also one of the most sacred sites for the O’odham people, including the Hia C’eḍ Oʼodham, or ‘People who live among the dunes,’ who inhabited this area for many millennia. 

As a place of crucial spiritual significance for the Tohono O’odham, this area merits the protection and respect one would be expected to show at any of the world’s most sacred sites. The most recent residents, the Hi’a C’ed O’odham, and their ancestors inhabited the area within the Reserve for more than ten thousand years, possibly forty, according to contested research that dates, what may be, stone tools found embedded in the natural desert pavements. It is widely accepted in any case that people were here during a time when the volcanic craters were full of water and the land was much less arid. The O’odham people in Arizona continue, to this day, a ceremonial pilgrimage on foot to the Pinacate, on which they would have traditionally collected precious salt and seashells – a form of currency. The tallest volcano, Santa Clara Peak, remains central to O’odham cosmology, being the second home, along with Baboquivari Peak, of I’itoi, or “Elder Brother,” a major O’odham deity.

The Pinacate Biosphere comprises a semi-dormant ‘Shield Volcano,’ and the surrounding ‘Erg,’ or sea of dunes known as the Algodones Dune Complex or Gran Desierto de Altar in Spanish (Great Desert Shrine). More than two-thirds of the Gran Desierto is covered by sand, and this is North America’s only Erg, or dune sea of more than 125 km2 (48 sq mi). This aeolian, or wind-blown sand, is the product of millions of years of sandstone erosion by the Colorado River and comprises the sandstone that once filled the Grand Canyon. The nature of these fine sediments and prevailing, seasonal winds create magnificent ‘Star Dunes,’ many more than 100 meters (330 ft) high, along with transverse or crescentic dunes to the East. The Biosphere Reserve extends from the US-MX border South to the edge of the northern Gulf of California (Sea of Cortez) and includes a portion of the coastline known as Bahia Adair, a critically important wetland habitat just south of the fishing community of El Golfo de Santa Clara. 

The northern Gulf of California is famed for having a fraught conservation history, that involves local small-scale fisheries, industrial trawl fisheries (mainly for shrimp), exploitation by bad actors, and the saga of the world’s most endangered marine mammal, the vaquita, or Gulf of California harbor porpoise (Phocoena sinus), a story that has touched the entire world. Less than a dozen of these porpoises are thought to remain in their small habitat, which is now strung with a web of nets that have been illegally placed to catch another protected species, the Totoaba drumfish (Totoaba macdonaldi).

A young Totoaba fished near Cholla Bay in the 1960s, photo courtesy of Annette Felix.
Totoaba being fished in the 1940s near Cholla Bay, photo sourced online.

Totoaba has been fished in this region since before the 1920s, when fishermen in dug-out canoes called Falullas followed them North to their spawning grounds at the Colorado River Delta, seeking the large fish for both their meat and an organ called the swim bladder. Today, the drum’s meat is mostly wasted, but the swim bladder, a false aphrodisiac – like most useless endangered species parts, is exported to black markets in Hong Kong and Taiwan. Known as the “cocaine of the sea,” this swim-bladder is taken via an illegal fishery that has long been controlled by drug cartels, including from as far as Sinaloa, and despite the occasional large bust, not to mention millions spent on failed, and some successful, conservation plans, the nets, and the illegal drum fishery remain.

Totoaba and swim bladders, photo sourced online.

Many local fisherfolk have no alternative options than to fish the Totoaba, and they are often brutally extorted by the cartels who will go so far as to make them pay for seized nets. What is more, all of this violence is fueled by the US arms trade, known as the “river of steel,” that allows arms to flow freely across the US-MX Border, and, of course, by the foreign consumption of illegal goods, from drugs to the prized swim-bladders, and more recently human trafficking. Since the mid-1990s, more than 400,000 Mexicans have died as a result of the bogus US War on Drugs and related cartel activity, and small fishing communities continue to suffer under the violent rule of bad actors. In Mexico, there is no rule of law, and instead of helping the US only provides the guns needed to continue a war on vulnerable people and habitats. When one makes an argument for conservation in such circumstances, many will point to the need for prioritizing social causes, failing to realize that local people and their habitat are deeply interwoven into the same social, economic, and cultural fabric (See my blog on the northern Gulf).

Original art by Alan Ruiz Berman.

A major milestone in the region’s conservation history was the joint protection of the El Pinacate Biosphere, together with the Upper Gulf of California and Colorado River Delta Reserve, an adjoining protected area northwest of the Pinacate. These ecologically interconnected biomes were finally protected in 1993, thanks to the support of diverse stakeholders, including the Mexican government, the Tohono O’odham Nation, and many people in the wider Tucson conservation community, including my supervisor at the Intercultural Center for the Study of Deserts and Oceans (CEDO), Peggy Turk Boyer, and the renowned Mexican ecologist Exequiel Ezcurra, a distinguished professor of plant sciences at the University of California, Riverside.

Corner map courtesy of CEDO.
Photo by Caleb Trainor with a permit from CONANP.

One can visit these unique protected areas, along with the protected Islands of the Gulf of California park, with special permission from CONANP, the federal body that manages all of Mexico’s Natural Protected Areas, akin to our US National Parks Service. To enter the Reserve today, a separate fee is also paid to local Ejidetarios – communal landholders whose Ejidos, or communal landholdings, a legal remnant from the Mexican Revolution, were grandfathered into the Reserve system. Ejido families have long petitioned the government for more funding in return for their being banned from grazing their cattle on these arid lands, in support of the Reserve’s conservation objectives, but seemingly to little avail. Their protests have resulted in decades of park closures, including the state-of-the-art solar-powered Shuk Toak Visitor’s Center, and the only approved route for visiting the dunes.

A 19th-century mine left its print in the otherwise flat, natural volcanic pavements.

At the same time, cattle have been increasingly allowed to graze on the meager pickings in this arid desert, and gauging cow footprints in the preciously ancient desert pavements that were absent a decade ago are now common. The primary campground is still absent a composting toilet, so one might say that recreational visits here are not so much encouraged as barely tolerated. This is rather paradoxical because an incredible amount of infrastructure has already been built for visitors, including the beautiful Visitor’s Center, along with two more half-built visitor centers (go figure), not to mention major paved and dirt roads that allowed me to visit even in my Nissan hatchback in 2010.

The Pinacate is so named for this black beetle (Eleodes spp.) because Santa Clara Peak looks like the black abdomen of the beetle when it is held up in the air in a defensive pose.

The Reserve also trains and certifies professional guides, including from the O’odham Nation, and there is excellent signage along the crater route. It is undeniable that if some of the many tourists who drive right by the Reserve on their way to Puerto Peñasco/Rocky Point, mostly from Phoenix and Tucson, paid to enter the Reserve, which is truly a wonder of the world and much more beautiful than anything in and around Rocky Point, that funding for the area’s protection could begin to flow. At the same time, there are plenty of conservation advocates who prefer less impact overall, and who are not unsatisfied with having a paucity of people in a place that is meant to be wild. Conservation is about compromise, but that is a word more easily said than done.

Another major issue is the cutting-off of critical ecological connectivity – the movement of animals and water – by the infamous Border Wall, which under the pretense of National Security was erected by bypassing every US environmental regulation. Indigenous graves, battlegrounds, and the region’s only ancient “fossil aquifers,” were blasted to erect the useless steel monument, which even proponents of strong border security have admitted does next to nothing to stop people from crossing the border. On the contrary, the new roads used to build the wall have granted access to previously uncrossable areas, facilitating smuggling. Instead of providing the direly needed legal infrastructure for processing immigrants, not to mention economic opportunities for people to work legally and in a mutually beneficial way, the US would prefer to arm the cartels and leave the world’s most vulnerable people at their mercy.

Of course, the cartels have no such mercy, and as has been known since the first Spaniards tried to cross it, neither does this desert. Every year, thousands perish on biblical-style journeys, made just north of the Pinacate, to find a better life, and the few non-government organizations trying to alleviate this death and suffering are criminalized by our elected leaders. As for the Border Patrol, they are so severely understaffed and underpaid that corruption is rife. During a recent wave of international migrants arriving at the border crossing in Sonoita, the Biden Administration simply shut down the major checkpoint, cutting off the economic lifeline for Puerto Peñasco which is almost entirely reliant on tourist dollars. 

Pinacate beetles burrow into the dunes collecting their flowery food in burrows.

The subtropical climate of the Pinacate’s Sonoran Desert environment is much hotter than southern Arizona, with an average annual temperature range of 18°C (64°F) to 22°C (72°F), and maximum temperatures averaging 49°C (120°F) and peaking at 56.7°C (134°F) in June. In winter, nighttime temperatures can fall to -8.3°C (17°F), though this is a rare low. The highlands have somewhat lower temperatures than average and are slightly more humid, but in general solar radiation is intense, evaporation is high, and relative humidity is very low.

The average annual precipitation in the Pinacate is less than 200 mm, with most of this rain falling in winter monsoons. Despite being a hyper-arid environment, the area has some semi-permanent rain-fed waterholes known as tinajas, that are formed in the lava and rocks and often last year-round due to bi-seasonal monsoon rainfall. These are crucial to the region’s animals, and once supported the Pinacate’s abundant human inhabitants, who would journey from one pool to the next via footpaths that are visible to this day.

The Pinacate is highly valued by the academic community, including by multinational ecologists, geologists, biologists, and archeologists working across borders to understand and bring recognition to the area’s unique flora, fauna, and human history. El Pinacate showcases a wide variety of geological and volcanic features. It is one of the few places in North America where one can see cinder cones, craters, inselbergs, and lava flows all in one place, as well as North America’s only erg, a vast dune ocean of a certain hectarage. What is more, the southern route from Tucson Arizona to the border town of Sonoita takes one through some of the most spectacular deserts of southwestern Arizona, with views of Kitt Peak, Baboquivari Peak, and Organ Pipe National Monument.

Coming from these lush green desert habitats to the moonscape of El Pinacate and witnessing the dramatic micro changes in floral and faunal communities across the northern Reserve is fascinating, especially to the eye of an ecologist. The variety of life and land results from its location at the confluence of the four Great North American Deserts, the Chihuahuan Desert to the East, the Great Basin Desert and the Mojave Desert to the northeast. With an abundance of rare and endemic species, the Pinacate hosts some of the highest biodiversity found anywhere in the world.

A Mexican bat researcher shows a biological sample in the form of a deceased native bat.

Particularly famous among its flora are diverse species of cacti, including the giant saguaro, organ pipe, nopal, agave, yucca, senita, and teddy bear cholla, all growing in a variety of distinct communities and flourishing under the shade of the desert ironwood tree, ocotillo, chaparral, and saltbush, keystone engineers of these sunbaked sediments. The fiery yellow flowers of the brittlebush in spring and creosote bush in summer, and the orange and purple wildflower blooms in Spring, along with the bright crimson cones of the ocotillo strike a beautiful contrast against the landscape’s dark obsidian floor, as do the feathers of the hummingbirds that hover among them.

Among diverse fauna, the chuckwalla, desert iguana, flat-tailed horned lizard, peregrine falcon, Chihuahuan raven, golden eagle, Sonoran pronghorn, big horn sheep, ringtail cat, and lesser long-nose bat are some that are commonly sought by wildlife spotting enthusiasts, but many more critters are lurking in the Pinacate’s wealth of habitats, including in its abundant caves and tunnels, which are hidden within the lava flows. Among my personal favorites are the horned lizard, the zebra-tailed lizard (below), and the Sonoran Desert iguana (Dipsosaurus dorsalis), which I have seen eating the berries of the creosote bush on the rim of El Elegante crater.

The Desert Iguana

The Zebra Tail Lizard

Among my favorite plants of the region is Pholisma sonorae, known locally as Camote, a perennial herb that grows in the dunes where it gets its water via stomata in its tiny leaves. Under the mushroom-like head with a ring of purple flowers, is a long fleshy root up to six feet in length, which was a crucial food source for Indigenous peoples. Absent chlorophyll to produce its food, this plant’s underground stem attaches itself to the roots of desert shrubs like wild buckwheats, ragweeds, plucheas, and Tiquilias (images below), stealing their nutrients, as a parasitic heterotroph.

The history of mankind in the Pinacate is evident in an array of archeological sites and artifacts, all of which are protected today. One can find the wares and paths of pre-historic peoples, including stone tools from the early Clovis Era, geoglyphs, petroglyphs, pottery, mortar holes used to grind foodstuffs, obsidian and stone arrowheads, historical artifacts from 20th-century Indigenous residents, items left behind by 17th-century colonial explorers like the Spaniard Melchior Diaz and the Italian Jesuit Missionary, Father Eusebio Kino, as well as the leavings of cowboys, outlaws, miners, explorers, scientists, and astronauts who came on the scene in the 19th and 20th centuries.

Father Kino was likely the first Westerner to climb Santa Clara Peak on muleback, and it was from here that he was able to discern that the Gulf of California was indeed a Gulf and not a channel as previously considered and that Baja was thus not an island but a monumentally long peninsula three times the length of Florida. Kino and other missionaries failed to convert the Comcaac and other warrior-like, nomadic peoples of the coast, and the O’odham of the Pinacate, most of whom did not take to mission life or values. The priests had greater success converting and controlling Indigenous peoples in the more agricultural regions further North, such as on the banks of the Santa Cruz River just outside of modern Tucson – a place where Indigenous peoples have had farming settlements for thousands of years.

Many of the Pinacate’s visitors across the ages traveled just North of the current-day Reserve, along the famed ‘Camino del Diablo,’ or ‘Devil’s Highway,’ which extends from Sonoita East towards Yuma – an ancient route leading to what was likely one of the continent’s densest meeting points for diverse indigenous populations coming from both North and South. One pre-colonial eyewitness account of the once lush Yuma valley describes campfires burning as far as the eye can see.

Geologically, El Pinacate is what is known as a ‘shield volcano,’ because from a bird’s eye view, it looks like a giant warrior’s shield. The dark areas are composed of extensive, hardened lava flows interspersed with hard-packed, wind-swept, multi-layered sediments known as ‘desert pavements.’ Santa Clara Peak is the highest peak in the Reserve, with an elevation of 1,190m (3,904ft). The name El Pinacate, used to refer to this mountain, comes from pinacatl, a Náhuatl (Central Mexican/Aztec) word for a black stink beetle that is endemic to the Sonoran Desert, and that you will likely come across as it leaves its little tracks atop the endless star and crescent-shaped dunes (image below). The tallest volcano’s graceful two-peaked summit looks much like the abdomen of this shiny black insect when it stands on its front legs in a defensive pose. In the O’odham language, the peak is called Schuk Toak, meaning simply, “Black Mountain.”

The Pinacate’s now dormant volcanoes erupted sporadically for a period of about 4 million years, with the earliest eruptions taking place 15-12 million years ago, and then again about 10 to 1.5 million years ago. The most recent activity likely occurred sometime between 7 – 11,000 years ago and was possibly witnessed by the area’s nomadic residents who have passed these experiences down through the generations via storytelling traditions. El Tecolote, perhaps the most pronounced lava flow, creates a stunning boundary wall where the molten magma cooled and stopped flowing. In the process, it formed a frozen river of sharp, jagged rock known as an A’a lava in the language of the Hawaiian people, possibly because that’s the sound one makes when walking over it. The other, smoother flows result from cooling at slower rates, and these are known as Pahoehoe flows in the same Polynesian tongue.

In addition to the lava flows and dunes, El Pinacate’s main attractions are twelve massive craters, eight of which are huge Maar-type craters, from the German meaning “crater lake”. These craters are formed when rising magma super-heats underground aquifers, creating pockets of pressurized steam that eventually, and sometimes repeatedly, pop like a bubble, causing the ground above them to collapse while also steam-blasting clay and ash that form cones of tuff breccia, a pudding-like stone cemented by the heat of the pyroclastic blasts embedding colorful ash and older sedimentary rocks into it. The submerged crater floors, once filled with water, are mostly flat and full of fine sediments. They host small groves of dryland trees such as mesquite, which thrive in these now-dry, ancient lakebeds, or playas (beaches). Some water still gathers at the center of these craters, during the rainy season, attracting big horn sheep, mountain lions, and other thirsty desert denizens.

Some of the craters I like to visit, with permission of CONANP, include MacDougal, Trebol, Sykes, El Elegante, and Cerro Colorado. Each is unique in its depth, diameter, shape, color, and habitat, making it very difficult to decide which crater is more beautiful and moving – each offering a different perspective, geomorphology, and host of unique communities of plant and animal life around and within. Nonetheless, I hold a special place in my heart for Cerro Colorado, a tuff cone around a crater with steep walls that are 300ft high and home to birds of prey and ravens.

Photo by Caleb Trainor

El Cerro Colorado

In 2009 I stood on the edge of The Cerro Colorado crater when a massive earthquake centered in Mexicali caused rockslides all around me, and I was very close to becoming a victim of the seismic shrug. I also fell in love with this crater on a visit with a loved one, and after magical spring showers produced a super bloom – colored bands of wildflowers decorating the surrounding playas as far as the eye could see. I was more fortunate to be able to bring lunch out to a BBC film crew and to help radio in their helicopter which was filming the purple, yellow, and pink rings that surrounded the volcanic features like banded skirts. I also helped them source local actors willing to play pre-historic people, including one of my colleagues who they asked to walk the sharp edge of the crater in bare feet! Sadly I have never seen the footage from this filming, but I did get to meet some esteemed videographers who were working in the field for months at a time, including the man who famously filmed a horned lizard squirting a coyote in the face with blood from its eyes.

Photo by Caleb Trainor

Nasa’s 1960’s Apollo Missions shamelessly used the sacred craters for testing lunar landing gear and left their mark on this rock.

Finally, there is the desert-sea connection that I mentioned before, and that is crucial to the local ecology and economy. Just South of El Pinacate, but still within the Reserve’s buffer zone, is Bahia Adair, recognized by the RAMSAR Convention on Wetland Conservation as a site of International Significance. This large, undeveloped bay is marked by numerous hypersaline, or “negative” estuaries, which host an incredible array of resident and migratory seabirds, wading birds, and other coastal marine life.

Perhaps the most abundant bird is the long-billed curlew, of which my friend Eric counted more than 75 during a one-stop visit. There are also a great number of sandpipers, herons, egrets, dowitchers, skimmers, and many more migratory bird species. Bahia Adair is also notable for its vast mud flats and the longest tidal flat on Earth, Along the margins of the bay halophytic, or salt-tolerant plant life abound, such as Distichlis palmeri, a saltwater marsh grass endemic to the northern Gulf and Islands.

Photo by Calen Trainor

Another abundant local plant, Salicornia, which is a genus of succulent in the Amaranth family, shows promise both as a biofuel and as feed for livestock – natural solutions for mitigating methane production and increasing organic carbon storage. Growing these plants at scale should be explored, provided we do not sacrifice our natural habitats and Indigenous lands to develop projects, however urgently needed they may be, and the fragile northern Gulf is not the only place where these plants grow, with Morocco and other larger deserts offering alternative options.

Photo by Caleb Trainor

The organic matter from halophytes, or salt loving plants, and other organic material is transported through Bahia Adair’s long, sinuous tidal channels (below), bringing nutrients out to sea, and creating a foundation upon which the entire marine food web in the upper Gulf is built. Bays and estuaries like Bahia Adair support around half of the Gulf’s fisheries, including blue crab, shrimp, and diverse fishes, and they are also crucial sinks for carbon gas. The sheer amount of turban shells I saw is a testament to the region’s incredible productivity. 

I hope that you will have the courage to visit the Pinacate responsibly, and like the region’s great ecologists, whose names are found all over the region’s modern maps, you will take the time to sit and contemplate the nuances and symbioses of an ecological system that turns environmental harshness and scarcity into beauty and abundance. We must continue to advocate for the protection of this special volcanic and dune habitat, of the Gulf’s wetlands, and of all places that are sacred to Indigenous peoples.

Photo by Caleb Trainor (Me contemplating El Trebol Crater with ravens above)


UNESCO Online Resources

CONANP Online Resources

SEMARNAT Online Resources

“Land of Black Volcanoes and White Sands, The Pinacate and Gran Desierto de Altar Biosphere Reserve,” Larry G. Marshall & Clark Blake, 2009

“The Devil’s Highway,” Luis Alberto Urrea, 2021

“The Sierra Pinacate,” Julian D. Hayden, 1998


Credited photography by Caleb Trainor

Text & uncredited photography by Alan Ruiz Berman

Acknowledgments. Thank you to:


Marcus Whitaker & Sonoran Rovers LLC

Eric Druhv 

Dr. Paul Dayton

Dr. Miguel Angel Grageda Garcia

Peggy Turk Boyer

The Intercultural Center for the Study of Deserts & Oceans (CEDO)