The Salar de Gorbea, some 13,000 feet above sea level, in the Atacama Desert of northern Chile, is like another planet. Active volcanoes dominate the muted, but colorful, vegetation-free landscape. In a few places, groundwater collects in salty, acidic pools. It evaporates in the sun, leaving behind gypsum crystals as big as your feet that protrude from the ground like daggers.
But they don’t stay put. Somehow they are scattered all over the place. And about three miles away it’s even weirder: It looks as if someone intentionally swept them into 15-foot-high piles, with some crystals merged together like giant gobs of rock candy.
How they got there was a mystery, until someone stumbled upon a whirlwind so powerful, it defied textbooks. In a paper published in Geology in March, Kathleen Benison, a geologist at West Virginia University, documented how what she calls a gravel devil may be responsible for the large crystals’ movement around the desert.
“I remember holding one of the crystals and noticing how they were all broken,” Dr. Benison said. “I looked up, and there was one of these gravel devils.”
She watched for five minutes as a huge white cloud that appeared to materialize in a valley between two volcanoes moved across the landscape and over the pools before it vanished, right above the gypsum dunes. This happened every afternoon during her three-day visit in March 2007, but it is unclear how regularly they occur.
Like windblown sand grains, the crystal surfaces were scratched, suggesting that the wind had carried them. But typically anything bigger than a grain of sand can be moved only by gravity or surface water. Desert whirlwinds aren’t supposed to be strong enough to carry anything as large as these gravel-size gypsum crystals.
But whirlwinds occasionally defy thermodynamic speed limits, said Nicholas Heavens, a planetary scientist at Hampton University who was not involved in the study but wrote a commentary about it. In Arizona, dust devils have been seen and proved capable of carrying small rodents, and in 2013, a ghostly wind ripped the side mirror off a police car in Hartford.
Dr. Heavens has no doubt that the gravel devil exists. It’s just extreme: To lift the crystals in the air and transport them, the speed at the center of a gravel devil must be around 150 miles per hour, he said. That’s at least the strength of an F0 tornado, and more like an F1.
He says he thinks the study of gravel devils may be a safe way to gain insights into how whirlwinds, including tornadoes, violate presumed speed limits on Earth. It may also reveal signs of extreme whirlwinds of the past if ancient gypsum deposits have a similar composition to these fresher ones in Chile.
But Dr. Benison, who found living algae and bacteria inside the crystals in Chile, is also interested in extreme life and how it can be preserved for thousands of years and transported via gypsum crystals. Recently in Mexico, scientists woke up microbes that were dormant for as long as 50,000 years in giant gypsum crystals.
And given the similarities in the climates in Salar de Gorbea and on Mars, Dr. Benison wonders if the crystals and dust devils here could serve as analogues for those that exist on Mars: “Can we look in those crystals and see the same kind of micro-organisms that we have in Chile?”