The stones move only every two or three years and most tracks develop over three or four years. Rocks that start next to each other may travel parallel for a time, before one abruptly changes direction to the left, right, or even back to the direction from which it came.

Tracks of sliding rocks have been observed and studied in various locations, most notably Racetrack Playa, Death Valley National Park, California. The first documented account of the sliding rock phenomenon dates to 1915, when a prospector named Joseph Crook from Fallon, Nevada visited the Racetrack Playa site.

This is one of those fun little mysteries that I am actually kind of sad has been solved, as was recently all over the media.

The culprit? A phenomenon called an “ice shove”.

[U]sing GPS and time-lapse photography, [t]hey documented a rock movement on December 20, 2013 that involved more than 60 rocks, with some rocks moving up to 224 meters between December 2013 and January 2014.

[R]ocks move when large ice sheets just a few millimeters thick start to melt during periods of light wind. These thin floating ice panels push rocks up to five meters per minute.

Like I said…bo-ring. I was really rooting for clowns sneaking in over the border from Nevada at night to push them with pry bars and clown cars.

Via Wikipedia.