Hundreds of mysterious engraved trails have been stumbled upon at the Racetrack Playa of Death Valley in California. There’s almost always a rock sitting at the end of the track, but no one has actually seen a rock — not a pebble nor a boulder — sliding on this nearly flat, dry mud surface. What gives? Several decades of speculation range from powerful winds and ice flotation to dust devils and slick films.
Now, for the first time ever, researchers have observed the sliding rocks in action. Finally! Under just the right conditions, thin sheets of ice blown by light winds push the rocks across the dry lake. The work, which turned out not to be “the most boring experiment ever,” was published in PLoS ONE this week.