The Mystery of Why This Dangerous Sand Dune Swallowed a Boy

When a boy suddenly disappeared into a sand dune, a scientist embarked on a quest to find out where he went

(Bryce Gehrls)
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But Argyilan did. When she learned that on the way to the hospital the boy had begun to show vital signs, it annealed her shame into resolve. “It was like a switch,” her fiancé, DeWet Le-Roux, told me. “She wanted to get to the bottom of it and maybe save others” from a similar—or worse—fate.

As the public deluged park headquarters with wild theories (lightning did it!), Argyilan spent late nights emailing prominent geologists and badgering park officials for new leads. When she asked Kilibarda, the resident Baldy expert, he told her someone must have dug a hole. “That’s still my leading explanation,” he said when we met. Just about everything else “simply disobeys physics.”


A month to the day after the accident, another hole was discovered: a saw-toothed maw a few hundred feet east of Nathan’s. Park officials called Argyilan, but by the time she arrived, the hole had refilled. Undeterred, she pounded in a coring tube. But the sand she extracted was perfectly ordinary. Investigators with the U.S. Environmental Protection Agency fared scarcely better. Their survey with ground-penetrating radar picked up 66 faint “anomalies”—irregularities inside the dune. What they were, the technology couldn’t say.

As news of the mystery spread, Argyilan began hearing from scientists around the world. Could the thawing of winter snow and ice, which can infiltrate sand, trigger a collapse? It wasn’t a terrible hypothesis, except that the accident happened in July. Another thought was that sections of clay undergirding the dune had eroded, allowing groundwater to pipe away columns of sand. Locals reminded Argyilan that there had once been beach shacks, wells and other structures behind Baldy. Might their roofs be caving, sucking down sand?

When Argyilan returned to Baldy last spring with a trowel and brush, she found a growing number of clues pointing in another direction: the black oaks buried decades ago by the dune’s inland march. Their crooked upper limbs still pierced the dune surface, like the arms of drowning men. If the trees were rotting from the inside out, would they leave tunnels? If so, how would those tunnels withstand the pressure of all that surrounding sand? They couldn’t—unless, Argyilan thought, the bark or maybe a decay fungus was releasing chemicals that somehow cemented the sand into a cast. She has sent samples to labs, but the tests hinge on the schedules of scientists with other priorities.

As she waits, she has had to hang on to just one, lonely parallel—on Facebook. Dina Pavlis, a U.S. Forest Service volunteer who leads tours and ranger training at the Oregon Dunes National Recreation Area, on the Pacific Coast, had posted photos she’d taken of deep, funnel-like openings in off-trail areas there. Pavlis told me she calls them “tree holes.” As in Indiana, wandering dunes are burying old forests. But no scientists have studied the Oregon holes, and their origins remain an enigma.


The park’s decision to close all of Baldy to the public after the accident turned out to be a shrewd one. Workers have discovered half a dozen new holes since, a sign that Baldy is not through with its mischief. Investigators now have to work in pairs and radio in on arrival and departure.

One bright and windy morning this past August, I followed a ranger up a chute of slippery sand onto Baldy’s western shoulder. I was there to see Argyilan and two of her colleagues, who were in the first days of what is expected to be an intensive yearlong investigation. Argyilan had pressed the National Park Service to enlist Thompson, her grad school mentor, who was now assistant research director at the Indiana Geological Survey. Thompson, in turn, brought in G. William Monaghan, a veteran geoarchaeologist with a lab at Indiana University’s flagship campus, in Bloomington.

Ducking under a strip of yellow tape, Thompson, in cargo shorts, aviator sunglasses and a reflective vest, spoke about the devices scattered behind him. The ones that looked like luggage carts bore ground-penetrating radar that would capture images of deformations up to 75 feet beneath the surface. The one that evoked a dentistry nightmare was a hydraulic coring drill called a GeoProbe that would pluck samples from deep within. The scientists’ goal: a navigable 3-D map of Baldy’s interior, a first-of-its-kind undertaking that might finally unlock the dune’s secrets.

“As the guy in the lab described it, you’ll put on glasses and take a walk through the inside of the dune,” Argyilan told me.


Dunes are the backdrop to beach vacations the world over, marvels of slippery geometry that mirror the shifting swells of the sea. Will dunes elsewhere sprout holes, too? Or is Baldy a kind of perfect storm, where the peculiarities of mineralogy, microbiology and climate have produced a singular freak of nature?

Either way, says dune expert Alan Arbogast, “if they are able to document a legitimate geological process, that would be news.”

I met Argyilan again later in the week at Shoreline Brewery, a restaurant a short drive from Baldy. Her father, Don, had joined us, to look after her daughter, Charlotte, now a cheerful 11-month-old.

I asked Argyilan what Thompson had meant when he said the eye sees only what the mind can comprehend. She said it had come up in a meeting, when he was asked why so many holes were suddenly appearing now. “His basic answer was, ‘Because we’re looking for them.’

“Mount Baldy is a great reminder that geological processes are still happening that are unrecorded,” Argyilan said. She nursed a pint of Singing Sands Oatmeal Stout as Charlotte toddled precariously around us, clutching her mother’s knee for balance. “You could have holes developing all through time and no one cares”—“no one notices,” she corrected herself—“until a boy falls in.”


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