Del Puerto Canyon: From the Earth’s Mantle to Mars in the Devil’s Range

Goat Trails
by Ryan Masters

Long referred to as “the door,” Del Puerto Canyon winds 22 miles through the Diablo Range, connecting the San Joaquin Valley to San Antonio Valley and, eventually, the greater San Francisco Bay area. The creek that emerges from the canyon was a vital stop on the long, dry El Camino Viejo. The Spanish called it Arroyo de La Puerta.

Del Puerto Canyon, however, is more than one door. It is many doors. It is a door to the center of the earth, a door to Mars, a door to the past; perhaps even a door to a parallel universe.

It is a remote and rugged place; otherworldly — one of the few places in the U.S. where fragments of the Earth's mantle have been thrust to the surface. An enormous and mysterious entity, the mantle is 1,900 miles thick and makes up 80 percent of the volume of the planet, but is so deep that humans have yet to drill to it. In other words, so far it’s deeper than greed; which is saying something.

Yet here, in Del Puerto Canyon, fragments of the Earth’s mantle have erupted into this world.

“The rocks of the mantle are described as being ultramafic, and they are beautiful,” writes Garry Hayes, a geology professor at Modesto Junior College. “They are literally composed of gemstones: lots of olivine (peridot), as well as bronzite pyroxene, diopside and other unusual minerals. They are valuable in other ways, as ultramafic rocks serve as ores for chrome, mercury, magnesium, platinum, nickel and other rare metals.”

I have come seeking odd bits of unusual minerals in the Earth’s mantle. And as one might imagine, it is as hot as goddamn Hades here. Like a fool, I have come in July. I begin the journey from the east, turning off Interstate 5 near Patterson and heading up into the golden hills of the Diablos. Out here, turkey vultures hunch on every available fence post. They compete for carrion with crows the size of dogs.

As I journey up Del Puerto Canyon, its walls tower over either side of the winding two-lane road, which follows the meandering route of the creek. Cattle paths are etched in tight, parallel lines across the canyon walls; they resemble terraced steps. In places, they transect near-vertical sections of the canyon. It is hard to imagine a cow managing such a precarious line. Here and there, a few head of cattle continue to graze, mostly along the creek, but the remarkable bovine architecture carved into the canyon walls suggests huge herds were run once here.

The unofficial entrance to the canyon is Graffiti Rock, an enormous roadside boulder aflame with teenage angst, professions of love, threats and pure joy. The graffiti has spilled off the boulder and on to the asphalt of the road. It appears “Chuy” has been here and, if he is to be taken at his word, Chuy will fuck me up if he finds me here with his girl.

The bright, chaotic paint makes the boulder look like some kind of spacecraft; like an exploratory mission to Mars from the planet Oakland. Del Puerto Canyon has long been a minor Mecca for UFO sightings. In fact, until 2006, a cult that worshiped extraterrestrials lived in the canyon. Neighbors reported that cult members regularly performed elaborate ceremonies in flamboyant costumes. They allegedly communicated with aliens using transmitters fashioned from minerals found in the canyon.

I leave Graffiti Rock behind and drive up Del Puerto Canyon Road. This is Yokuts country. Some of the caves dotting the canyon walls serve as tombs for their ancestors and mortar rock grinding stones can be found along the creek.

As I make my way up the gorge, I am – from a geologic perspective – climbing through ancient oceanic sediments towards the Earth’s mantle. This crust is known as Coast Range Ophiolite and is thick with marine fossils. In my mind’s eye, the organisms squirm and slip through the stone around me as I ascend in my Jurassic submarine.

As I round a bend, a magnificent dike of quartz juts out from the Ophiolite like a great white rooster comb. From high overhead, the massive band of quartz plummets down the canyon wall and through the road before me. When I pull over, I find a massive steel door set into the vein.

With effort, I swing open the heavy, unlocked steel door and step into a chamber of shadowy quartz. The vein has been mined for gold, unsuccessfully from what I understand. Yet standing inside a room of natural quartz, even quartz covered in cartoonish graffiti, is its own treasure. It feels magic in here. As if I’ve been transported.

Del Puerto Canyon is one of those places where the wall between dimensions or realities appears to be thin, at places flimsy – even permeable. Over the years, stories have emerged; tales of people who have stepped through other kinds of doors, doors without visible frames or thresholds.

In perhaps the most infamous incident, a Livermore man traveled to a parallel universe and returned with a previously unreleased Beatles album. On Sept. 9, 2009, "James Richards" was chasing his dog through Del Puerto Canyon when he stumbled, knocked himself unconscious and awoke in an alternate universe.

In this other reality, Del Puerto Canyon was densely populated, ketchup was purple and the Beatles had not broken up. Before returning, Richards managed to steal a copy of a new Beatles album titled “Everyday Chemistry.” (Find out more about his bizarre tale at

Just east of Frank Raines Regional Park, named after an otherwise unremarkable turn-of-the-century Stanislaus County supervisor, I take a long walk through the Minniear Day Use Area, which is accessible through a series of gates.

Littered across the riverbed I find gorgeous chunks of jasper – colorful chert stone that can be polished to a jewel-like luster. It’s a stretch to call jasper even “semi-precious,” but its rich, unique colors are irresistible. After two hours, I return to the car with my pockets full.

As I near the Earth’s mantle in Del Puerto Canyon, the iron-rich earth is stained Mars red. Most of the rock is serpentine, a brittle stone that looks like dragon scale with psoriasis. When I clamber high up the steep, ochre walls into hidden rivulets and niches, I find the canyon is riddled with old mineshafts. Most are back-filled and shallow, but others wend deep into the earth. During much of the last century, chromite, the source of chrome, and magnesite, were sourced from a vast network of local mines.

New Age mystics believe that magnesite aids the “development of psychic visions of exceptional clarity.” The UFO cult used it as an extraterrestrial transmitter. Before you scoff, bear in mind that magnesite was detected in meteorite ALH84001 and on Mars.

Historically, magnesite is best known as a key to the process of making steel. Before World War I, 70 percent of all magnesite was imported from Austria and Greece. As a result, the need for vast amounts of steel during the Great War spurred a magnesite rush in the Diablo Range.

In Frank Raines Regional Park, a plaque memorializes the Patterson and Western Railroad, which transported magnesite, manganese chrome and quicksilver down Del Puerto Canyon from Sept. 20, 1916 to Aug. 14, 1920. To reach one mine, a 3,000-foot tramway was constructed up the side of the canyon.

Today, most reminders of these boom times have slowly settled beneath the dirt. Yet one of the greatest treasures of Del Puerto Canyon can still be found a bit further up the road. Old Adobe Springs is a magnesium-rich spring. You can fill a water truck up for a fee or just gorge yourself at the free spigot. It tastes absolutely heavenly.

Old Adobe Springs is also of great interest to planetary and space scientists. That’s because the Del Puerto Ophiolite is remarkably similar to certain Martian geology. As an analog, these scientists believe Del Puerto Canyon may contain the answer to whether water—and thus, life—is on Mars.

Doors within doors within doors.