Surprise: Enormous 'Star Dunes' Move

The most detailed study to date of enormous sand formations known as "star dunes" may explain why they are largely absent from Earth's ancient geological record—they are apparently younger than we've long thought. Coverage:

• What are they? Star dunes are huge deposits of sand formed by opposing winds in the deserts of the world (and even on Mars). As Reuters notes, they look a little like pyramids from the ground but more like stars from above. They can rise to heights of 1,000 feet, with "arms" of sand sprawling far and wide in different directions. They are "extraordinary things, one of the natural wonders of the world," says Geoff Duller of the UK's Aberystwyth University, a co-author of the study in Scientific Reports.
• The study: Researchers used ground-penetrating radar to study Lala Lallia, which is in Morocco and one one of the world's biggest and most complex star dunes, reports the BBC. They found that its base formed about 13,000 years ago, but the dune then stopped growing for thousands of years. It wasn't until the last 1,000 years or so that the dune grew into its current form, a relative blink in the geologic record, per a release at Phys.org. "These findings will probably surprise a lot of people as we can see how quickly this enormous dune formed," says Duller.

• It's moving: Another surprise is that researchers determined that a steady wind from the east is causing the dune to move westward across the desert at a rate of about foot-and-half per year, per the Guardian. "That's important when you're thinking about building roads, pipelines, or any sort of infrastructure," says Duller. "These things actually do move."

(More desert stories.)