Whirlwinds are pretty common things. They’re essentially baby tornadoes, rotating vortices of wind that form all over the world, and even on Mars. There are plenty of nifty varieties that don’t just involve light dust, including snow devils, steam devils, leaf devils, and fire whirls – all featuring exactly what you’d expect them too.
Now, as reported in the journal Geology, there’s a bizarre new whirlwind in town. Named “gravel devils”, these swirling masses contain predominantly gypsum, a type of beautifully iridescent elongated crystal. Gypsum is translucent, but often is colored slightly pink, green, yellow or blue, which means that these miniature cyclones can take on a variety of reflective hues. This, however, isn’t the unusual part.
Somehow, huge and heavy clumps of these crystals – with some individual examples reaching lengths of 27 centimeters (nearly a foot) – are being effortlessly levitated by these wind instabilities. Suspended in whirlwinds up to five American football pitches across, these blade-like crystals are transported for several kilometers down Andean valleys before suddenly being deposited en masse as the vortex evaporates into nothingness.
As was observed in the Chilean Andes by Kathleen Benison, a geologist at West Virginia University, these gravel devils can be spotted dancing within the volcanically-shaped high-altitude plains of Salar Gorbea.
Some of the blades fallen out of the gravel devils. Kathleen Benson/Geology
The gypsum itself forms when extremely saline and acidic pools of water begin to evaporate in the afternoon sun. These crystal daggers are then picked up by the ephemeral gravel devils, which move quickly and only exist for around five minutes at a time.
It’s likely, although not certain, that the unique geology of the Andes ensures that this is the only place on Earth that gravel devils exist. It helps that the landscape there funnels the wind in a way that favors the development of vortices, and that gypsum crystals are so light that they’re easily lifted off the ground.
Only Antarctica, with its peculiarly powerful winds, may also be a candidate for wind-levitated gravel chunks. “Regardless,” Benison notes in her study, “it is speculated that the gravel devils of Salar Gorbea may be the largest and strongest known on Earth.”
Some rather menacing red and black gypsum crystals. Albert Russ/Shutterstock
So there you have it. The Andes are a true natural wonder of our planet, full of dramatic peaks and valleys and extremely bizarre forms of life. Now they also happen to feature shiny gravel devils, and perhaps if you pop on over there, you might be one of the first people on Earth to see them in action.
[H/T: Science News]
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