Deep in the heart of the California desert lies one of the natural world’s most puzzling mysteries: the moving rocks of Death Valley.
These are not ordinary moving rocks that tumble down mountainsides in avalanches, are carried along riverbeds by flowing water, or are tossed aside by animals.
These rocks, some as heavy as 700 pounds, are inexplicably transported across a virtually flat desert plain, leaving erratic trails in the hard mud behind them, some hundreds of yards long.
They move by some mysterious force, and in the nine decades since we have known about them, no one has ever seen them move.
Until now that is!
Racetrack Playa is the seasonally dry lake (a playa) located in the northern part of the Panamint Mountains in Death Valley National Park, California, U.S.A. that is famous for ‘sailing stones‘.
One cold winter morning, when the snowmelt covered the playa, the solution to the puzzle was finally caught on film.
That kick ass photo above is by MeLastMohican. I have no idea what his real name is, but he
That really is a trip … it does make me a little sad, though, that I didn’t go down to Black Rock City this year for the Burning Man festival. Man dad is a geophysicist and he really enjoys the ‘racing rocks’ phenomenon because geological time is usually so slow!
Wow.. it’s odd that it washes over some rocks, completely ignoring them. I guess it’s a matter of which area of water is the most dense. Forwarding this one to a few friends :)
MG, all bodies of water and sections of those bodies of water will have the same density…I think it would depend on current or the size of the rocks, possibly how deep they are embedded?
It is also interesting to note that the crinkled surface of the mud remains relatively unchanged. I am guessing that the mud is frozen or baked hard so that the water flow doesn’t change it but a rock dragging across the surface would. Without that video, one would have to assume some hippies from Burning Mans wondered over in the night and did the rearranging.
I wonder if the clay surface of the dry lake bed contains the mineral called Kaolin? Kaolinite is a clay.It is a soft, earthy, usually white mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. In many parts of the world, it is colored pink-orange-red by iron oxide, giving it a distinct rust hue.It is widely used as a replacement for talc.It is also used as a lubricant.It is what gives glossy paper it slick shiny appearance.
If kaolinite is leeching out of the clay when it is wet or submerged with water the surface would become very slick!
I just watched the video but I never actually saw a rock moving just the water flowing.
I noticed the same thing ! It seemed easy to zoom in on stationary stones, but no inclusion of a stone suspended by the water with a close-up of how the water was actually acting on the stone. Ice would do it, I guess, but there’s a whole set of hydrodynamic issues as to the effect of Ice both on the stones and the soil. I could see Ice, maybe, but nothing in the video was definitive. RATS !
The Dunning video was incredibly irresponsible. It showed no stones moving, yet claimed to be the explanation. The real reason the stones slide is due to the common phenomenon known as frost heave. Ice lenses form beneath the surface at the freeze thaw boundary heaving the soil upward and creating a slope for the stones to slide down.
What nonsense! The real reason is the rocks are magic rocks.
Obviously! ;)
You’re making quite a bold assertion yourself sir. One of the most notable aspects of the racing stone phenomenon is that the ground, other than the tracks, remains unaltered. Additionally, the slope of the plain is highly monitored (the elevational difference between the two ends of the valley, about two miles apart, is less than one inch). On top of that, some of these tracks are miles long and were made by stones up to 700 pounds. You mean to say that an entire mile-wide stretch of ground was tilted at enough of an angle for a 700 pound rock to slide all the way across it, and then the ground was restored to its exact previous state without leaving any kind of visible fractures or other alterations to the terrain?
same here. also, why wouldn’t stones be dragged back as water receded.
Also look at thisSliding Rock Locations and Trail Lengths, July 1996. The video doesn’t explain why the rocks have different patterns in their movement and generally move uphill (the northern section of the playa is a few centimetres higher than the southern end)
Another short but interesting read The Racetrack Playa – Death Valley, California
water seeping upward through the ground freezes on the surface in cold times. I have previously observed these long icicles which appear to grow from the ground and carry topsoil. The frozen crystals should have sufficient power to move the rock very slightly in the upward direction. When the sun shines again, it causes the ice to melt where there is no shadow, causing the rock to sag in that direction. Upon sagging “forward” the rest of the ice will melt or alternatively the ice will grow under it again. This causes an inching effect, the reason for the paths is that the ice will generally grow everywhere, however the rock has a compaction effect of the ground it is situated on. Irregular rocks have irregular shadows and hence the differential preference in direction, direction can change depending on the time of year and the position of the sun relative to the rock, there is also the possibility of rock rotation, based on the same principle. Does anyone agree?
:-) Knowing how the trick is done doesn’t make it any less magical
What I think needs to be added to the explanation is the effect of pore pressure at the interface between the bottom of the stone and the wet mud surface. Pore pressure is a resisting upward force generated by a film of water that occurs around and between mud particles and confined by the block of rock above it. Since water is virtually incompressible, the object is able to move laterally in response to a temporary current produced by the advancing edge of the temporary lake. But the pore pressure “buoys” up the rock, and it can slide on extremely low slopes, such as that of the playa (normally an intermittently wet, surface of deposition in a dry climate environment.
It is sort of analogous to hydroplaning tires on wet pavement. The tires are not in contact with the pavement because of the film of water between the tires and the pavement. Water cannot be compressed, so any confined water in the tread builds up pore pressure, and floats the car (or the rock). Sometimes you can see a water glass with a wet bottom slide in funny directions on a table.