The Racetrack Playa is an exceptionally flat and dry lakebed located above the northwestern side of Death Valley, in Death Valley National Park, California. The playa is best known for one of the most strangest mysteries of the planet – the sliding rocks. These rocks can be found on the floor of the playa with long trails behind them. Although no one has actually seen the rocks move, the long meandering tracks left behind in the mud surface of the playa attest to their activity. Some of these rocks weigh several hundred pounds and have traveled as far as 1,500 feet, which leaves us with the question: "How do they move?"
The stones move only every two or three years and most tracks develop over three or four years. Stones with rough bottoms leave straight striated tracks while those with smooth bottoms wander. Stones sometimes turn over, exposing another edge to the ground and leaving a different track in the stone's wake.
Trails differ in both direction and length. 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 the direction it came from. Trail length also varies – two similarly sized and shaped rocks may travel uniformly, then one could move ahead or stop in its track.
Despite a century of scientific investigation, this curious phenomenon has confounded the geological community and park visitors alike. To this day, no one has ever seen the rocks move. But in lieu of eyewitnesses, countless theories have been put forward over the years in an effort to explain the reasons behind the migrations.
One early suggestion was that the rocks were driven by gravity, sliding down a gradual slope over a long period of time. But this theory was discounted when it was revealed that the northern end of the playa is actually several centimeters higher than the southern end and that most of the rocks were in fact traveling uphill.
Though no one has yet been able to conclusively identify just what makes the rocks move, one woman is coming closer to solving the mystery. For the past ten years, Dr. Paula Messina, professor of geology at San Jose State University in California, has been tracking the movement of each of the 162 rocks scattered over the playa. Her research suggest that a rare combination of rain and wind conditions enable the rocks to move. A rain of about 1/2 inch, will wet the surface of the playa, providing a firm but extremely slippery surface. Strong winds of 50 mph or more, may skid the large boulders along the slick mud. At an elevation of 3,700 feet, strong winds can rake the playa at 70 miles per hour. But even small gust of wind may move the rocks.
Some people have suggested attaching radio transmitters to the rocks or erecting cameras to catch them “in the act” in order to put an end to the speculation. But as Death Valley National Park is 95 percent designated wilderness, all research in the park must be noninvasive. It is forbidden to erect any permanent structures or instrumentation. Further, no one is permitted on the playa when it is wet because each footprint would leave an indelible scar.
.jpg){kind=link}
Wow! Its obviously happening when wet so she may be on to something.
ReplyDeleteYes
ReplyDeleteI agree. If marks from people are only left when it is wet, same for the rocks... Furthermore, this is the desert, and a very thin layer of ice can quickly form on the ground in winter when it is very cold, so that may help as well... (I live in CA and we've stopped there a few times driving to Las Vegas. Death Valley is worse than Vegas in summer with 120+ degrees, and below freezing in winter! For some reason, there's always Germans there, but not at other CA sites, even other geologically interesting sites. Why?!?)
ReplyDeletewhy doesn't somebody set up a long term weather protected camera????
ReplyDelete"no one is permitted on the playa when it is wet because each footprint would leave an indelible scar." ... yawn... more tree huggers...
ReplyDeleteor sand-huggers as it were.
DeleteSeems putting a heap of weather sensors & cameras on the peripheral hillsides and plugging the data into som decent modeling software would answer a lot of questions. Adequate sensors and data loggers are pretty cheap nowadays, you can get it at Costco/BJ's/Sam's/etc. Still not "cheap", maybe crowd-funding?
ReplyDeleteI wonder if the content of the rocks includes any metal, which might react to a magnetic "pull".
ReplyDeletei believe the answer to this lies in my house. I have a glass kitchen table, and from time to time, whenever i sit to eat there is a plastic cup i use to drink from, said cup has a tendency to move on it's own without aid of physical contact or wind or shaking the table.
ReplyDeletei've not paid it much serious thought after the preliminary scare that I might be psychic, but after reading this, I'm curious if the two matters are linked. someone above mentioned the ground could freeze with a thin sheet of ice, hence creating similar conditions.
said cup, is filled with liquid weighing it down, the presence of wind(air) is still present but not strong enough to move a weighed down cup, there is movement of the surface on which both objects lay, both at a small degree, which again can't cause it to move. simulating the conditions somewhat on a micro scale. HMMMMMMM~
Prob a ghost....OOOOOOO
ReplyDeleteyes, lets preserve this national heritage of sand.... can't let any nasty footprints harm that precious sand. How would we ever know what it looked like under those footprints?!
ReplyDeleteIt was found that water collects as a shallow lake and the top freezes over, trapping the rocks. When the ice begins to break up there's enough drag on the ice to pull the rocks along. This is why sometimes several rocks close together will have similar tracks and sometimes rocks that had been in the same piece of ice will end up being dragged in different directions when the next ice breaks up differently.
ReplyDeleteIf the combination of water, ice, and high winds required to produce this result was more common and in a more hospitable location then it would not have lasted as a mystery for so long.
Even knowing the answer, the result appears so divorced from the cause to remain as interesting as any other natural wonder.