It is one of Death Valley’s most intriguing geological whodunits — the sliding rocks of the Racetrack Playa.
On an ancient lakebed located on the western side of Death Valley National Park, boulders that weigh up to 700 pounds sail across the almost perfectly flat terrain, leaving grooved trails in their wake. As NATURE’s Life in Death Valley shows, each of these furrows chronicles a rock’s journey, ranging from a mere few inches to nearly 3,000 feet. Some tracks manifest in straight bold lines, while others coil back on themselves in sinuous arcs.
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.
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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 made it her quest to understand what has bewildered geologists for decades. “It’s interesting that no one has seen them move, so I am kind of sleuthing to see what’s really going on here,” says Dr. Messina.
Many scientists had dedicated much of their careers to the racing rocks, but the remoteness of the area kept their research limited in scope. No one had been able to map the complete set of trails before the advent of a quick, portable method known as global positioning. Dr. Messina was the first to have the luxury of this high technology at her fingertips.
In 1996, armed with a hand-held GPS unit, she digitally mapped the location of each of the 162 rocks scattered over the playa. “I’m very fortunate that this technology was available at about the same time the Racetrack captured my interest,” she says. “It took only ten days to map the entire network — a total of about 60 miles.” Since then, she has continued to chart the movements of each rock within a centimeter of accuracy. Walking the length of a trail, she collects the longitude and latitude points of each, which snap into a line. She then takes her data back to the lab where she is able to analyze changes in the rocks’ positions since her last visit.
She has found that two components are essential to their movement: wind and water. The fierce winter storms that sweep down from the surrounding mountains carry plenty of both.
The playa surface is made up of very fine clay sediments that become extremely slick when wet. “When you have pliable, wet, frictionless sediments and intense winds blowing through,” offers Dr. Messina, “I think you have the elements to make the rocks move.”
At an elevation of 3,700 feet, strong winds can rake the playa at 70 miles per hour. But Dr. Messina is quick to point out that sometimes even smaller gusts can set the rocks in motion. The explanation for this lies in her theory, which links wind and water with yet another element: bacteria.
After periods of rain, bacteria lying dormant on the playa begin to “come to.” As they grow, long, hair-like filaments develop and cause a slippery film to form on the surface. “Very rough surfaces would require great forces to move the lightest-weight rocks,” she says. “But if the surface is exceptionally smooth, as would be expected from a bio-geologic film, even the heaviest rocks could be propelled by a small shove of the wind. I think of the Racetrack as being coated by Teflon, under those special conditions.”
In science, hypotheses are often based on logic. But over the years, Dr. Messina has discovered that on the Racetrack, logic itself must often be tossed to the wind. “Some of the rocks have done some very unusual things,” she says.
In her initial analysis she hypothesized that given their weight, larger rocks would travel shorter distances and smaller, lighter rocks would sail on further, producing longer trails. It also seemed reasonable that the heavier, angular rocks would leave straighter trails and rounder rocks would move more erratically.
What she discovered surprised her. “I was crunching numbers and found that there was absolutely no correlation between the size and shape of the rocks and their trails. There was no smoking gun, so this was one of the big mysteries to me.” What appears as a very flat, uniform terrain is in fact a mosaic of microclimates. In the southeastern part of the playa, wind is channeled through a low pass in the mountains, forming a natural wind tunnel. This is where the longest, straightest trails are concentrated. In the central part of the playa, two natural wind tunnels converge from different directions, creating turbulence. It’s in this area that the rock trails are the most convoluted. “What I think is happening,” proposes Dr. Messina, “is the surrounding topography is actually what is guiding the rocks and telling them where to go.”
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.
As for Dr. Messina, she is content in the sleuthing. “People frequently ask me if I want to see the rocks in action and I can honestly answer that I do not,” she says. “Science is all about the quest for knowledge, and not necessarily knowing all the answers. Part of the lure of this place is its mystery. It’s fine with me if it remains that way.”
I dont think this can be a magnetic field effect. Magnets exert force if AND ONLY IF there is a gradient (a continuous change) in field strength. In uniform magnetic fields, which is the case given the scale of these rocks compared to the size of the earth, all magnetic fields can exert is torque, no work can be done. This is why compass needles dont slowly bend their balance toward north. I cant say anything about any electro-static forces but i do not think this could be caused by magneto-statics.
My theory is something along the lines, if you were put a beach chair at the edge of the ocean and you sit in said chair with your feet in the sand, when the water rushes up around your feet and then resides back to the ocean you can see a “trail” where the water eroded the sand from around your feet. This would somewhat explain how the rocks are “traveling uphill” I’m not a scientist by the traditional definition, I just enjoy the sciences. If I’m wrong, please tell me and explain how. I look forward to the responses!
i have no idea of how this happens there, but it does remind me of how as a kid my dad would take us to florida and in some places one could stop the car and turn it off. it would still move uphill a small ways. so maybe what ever causes that is at play there? but really if it was that simple the scientists would have already figured it out. just thought i would put my thoughts out there to. i have not thought of those places in florida for decades.
I’d say alot of really smart people here. Just to dumb to research anything. Just a bunch of guessing. You need to start with the birth of Death Valley range. I’ll let ya’ll smart guys out there figure on it, while my dumb red-neck farm bred boy goes on out back and watch a Toronader slide a rock crossin ma pond.
You have to take a peek-see overn dere on da otta side of da fence. See ole Ralph has this pig that wollers in the mud. and damnin he dont get into that thang them people on the coast a.do, Oh, Piggy Wallerin, That be it.
Wel’n one winter long come a nasty blizzard that left 2.5′ snow there in the lower plains of ma back yard. Naw ole Ralphs a boar “8 Ball” as mean as the devil himself. Just to darn dumb to headin for shelter. Heard a Ralph out’n there just for the storm a settled in just a cursing and whoppin on ole 8 Ball. Ralph, soon gave up to roost his yard birds. Left Ole 8 Ball to fiend for himself.
Come next mornin, I heads on out to have me some a funnin for ma gets up and tends me to ma chores. Well, I’m a out on my 4 wheeler rig lookin for some good ole white snow mug runnin, cutting near the back of the ole forty I spots me a muddin hole. I thinks to maself, “boy, dar be some mudding overn dar on Ralphs place”, So, I jumps off ma rig and heads over for a closer peek-see. And damn’n if Ole 8 Ball just a rolling and enjoyin himself so much. I was stump’d. Thinks in ma head. ” boy, how a comin dis ole pig aint on ice?” Hmph! ” nowin dat make no darn sencin ta me. I heads on up ta Ralphs and goes to askin him how come ole 8-Ball aint a frozen.
Well by-gawd! Dat ole pig a bin wholler’n right there in adarn ole hot mud pit. It a looked like ma wifes S.O.S. S_it on Shingles. Just a hot’n steamy. Sorta burnt bit,Can tell it’s right when it bubbles and pushes the clumps about.
Ya’ll know what I’ma telling ya. Right? Figured So’s much.
Thank you all for listening to my story.I think if you research the history and pick up on the clues, Without influence and an open mind, forget about theory and think more about Earths evolving, You’ll see that the earth is elaborate system of caverns, caves, oil, gas, water and FIRE. It all works together untill something fails. Then we have Natural Distaters…..
I believe Steve’s got it: … read what Steve Griffith’s comment obove from February 25, 2010 at 2:04 pm says.
:^}
It’s a hoax like the bigfoot footprints or crop circles. The rocks don’t move. Someone is creating the tracks, making it look like the rocks have moved.
What about local liquefaction under and/or in front of the rock?
So… to all these theories about ground water and such… you all do realize this is Death Valley, right? As in, like NO rain. Not literally none, but not enough to “wash away” the rocks. We are talking cm of rain, throughout a whole entire year. Not exactly enough to account for anything except maybe some of the theorized surface ice. I don’t have the answer, just pointing this out.
I believe it’s a combination of water, silt, wind, gravity, and magnetic (possibly affected by lunar gravitation) effects that cause the movement. If it was caused by one singular solution it would’ve been explained long ago.
One thing’s for sure, one shouldn’t get angry if your hypothesis isn’t automatically accepted. Only pure proof will get you that, and people have been trying to explain this phenom for decades, with very little success.
Lil Ol’ Me, that’s not really possible because there isn’t any water in that area and even if there were, it wouldn’t leave a trail that long since the objects in question aren’t that tall.
Surely the likes of Google Maps or Near Maps can take regular images of the place. May not catch the smaller stones, but the big ones will be easy enough to identify.
Wonder if freezing and thawing have anything to do with it? If ice forms at one side of the rock before the other, there’s a small but significant “lift” on that side of the rock. Would it be enough to move the rock? I have no idea. But it could explain why some rocks change paths – the ice doesn’t form on the same side each time.
Can someone please call Mythbusters to the rescue?
I thought nat’l parks said take only pictures, leave only footprints. And we aren’t allowed in the name of science?!
This is the desert, at night it is very cold and during the day these rocks get VERY hot. Each rock only moves half a mm or less per day, but it is the massive change in temperature every day that creates the very small movement and diff. in temp and mosture of sand around rock vs. under it. (wind/gravity/magnetic forces + other have nothing to do with the movement). The darker the rock the more itcan move as it gets hotter. The shape at the front of each rock will also affect the movement some. Line up 2 rocks, paint one white and one black for heat differnce and watch the black rock move vs. the white rock…. or put a sun sheild over the top of one rock and watch it stop moving. The pattern of the sun in the sky also will slowly affect the rock movement. most rock movement is fairly straight line with some minor curving. You need a thermal camera to see how hot the rock vs. the sand temp is to really understand what is happening. You also need a microscope to see at the rock edges and under the rock. It would be easy to sent up some fun experiments to watch this…but if you are not in the desert, your experiment won’t match what is happening…
——This is the desert, at night it is very cold and during the day these rocks get VERY hot. Each rock only moves half a mm or less per day, but it is the massive change in temperature every day that creates the very small movement and diff. in temp and mosture of sand around rock vs. under it. (wind/gravity/magnetic forces + other have nothing to do with the movement). The darker the rock the more it moves. The shape at the front of each rock will also affect the movement some. Line up 2 rocks, paint one white and one black for heat differnce and watch the black rock move vs. the white rock…. or put a sun sheild over the top of one rock and watch it stop moving.
Faith moves mountains. What are mountains made of?? ..Rock..
During the rainy season a shallow lake forms at one end of the playa. You can find video on YouTube of the water in that lake quickly being driven across the surface of the playa by high winds. It also gets cold enough at night for ice to form on the surface of the ice.
I suspect the water surrounds the rocks and turns the playa’s surface into a slick, thick mud with a reasonably firm surface that can support some weight. If you have ever tried walking on a mud flat (growing up on eastern Long Island I have) you will know that such mud can become very slick and slippery but will support a person’s weight. I have fallen more than once trying to walk on the stuff.
At night ice forms on the surface of the shallow standing water. Winds blow the ice around. The ice hits the rocks applying force to them, and the rocks are pushed across the slick surface, leaving a trail in the mud.
When the water goes away and the mud dries, you see the rocks have moved.
Occam’s Razor generalizes that the simplest explanation for a phenomenon is the most likely. This tosses out
aliens, magnetic fields and ants. Some pictures show rock trails traveling in different directions; if gravity or wind were powering the movement, the trails would be parallel in a small area. This leaves the relevant factors of water, slippery clay and flat bottoms of the rocks plus local changes in the climate: The high playas of Death Valley experience a dramatic temperature range. If rocks move in different directions and only when the clay is wet, a reasonable hypothesis would be that the mud freezes under the rocks and lifts them; then sunshine melts the ice first on the East, South or West side, depending upon the time of sun exposure and color and geometry of the rock. The collapse of ice crystals under the rock allows the rock to subside in that direction, thus moving it by small increments. Over time the increments add up to a long trail.
Tests of the hypothesis: 1. Do rocks ever move due North? 2. Can a smooth bottomed rock in a level, slippery, controlled environment be shown to move similarly in response to water freezing at night and melting in sunshine?
Why not leave several different metal sheets out there. Also, you could leave different rocks, potential magnetic and non magnetic. In this way you could see if any of them move, and then narrow down which force is acting on them.
Some of you scientific minds might look into the fact that clay swells when wet and is slippery when wet. And the swelling and wet cycle of death valley playa is what moves the rocks. Swelling of wet clay. Think about it???
I ve seen the rocks in death valley. It is the wind and water, but this area has mini torados blowing thru all the time. Which can drag rocks in funny ways specially when ground is wet and catches them,but can t lift them. It sometimes spins them to move. I thought about it and I am sure this is the answer- mini desert tornados.