For over 50 years, researchers have been unable to explain why stones have appeared to move on their own across Racetrack Playa at Death Valley National Park. Now, there’s finally an answer.
Richard Norris and James Norris at the Scripps Institution of Oceanography at University of California San Diego set out to finally find an answer to the half-century mystery, and in order to figure it out, they placed stones with GPS devices on the stretch of land and waited. They also set up cameras to monitor the area.
On December 20, 2013, Richard and James, who are cousins, finally got the answer they were searching for.
“It was a beautiful sunny day, and there began to be rippled melt pools in front of us,” said Richard Norris. “At 11:37 a.m., very abruptly, there was a pop-pop-crackle all over the place in front of us — and I said to my cousin, ‘This is it.’”
Ice began to move past the rocks, and although it wasn’t visible to the human eye because the movement was so slow, the rocks began inching along. By the time the ice had melted that afternoon, they saw that there were trails left behind by the rocks from where they were originally placed. On that day, more than 60 rocks moved.
Early the following month, James Norris returned to the area and was able to capture more rocks moving on camera.
"We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras," wrote the researchers in a study. “In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, three to six [millimeter], “windowpane” ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of (about four to five meters per second).”
So, after 50 years of wondering, the researchers were able to determine that ice panels pushed the rocks at extremely slow speeds.
“Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2–5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice,” wrote the researchers in the study.
Check out time lapsed footage of the rocks moving below.
Photos Source: ABC News