Death Valley 's moving rocks.

[GreatCaesarsGhost]

what do you think moves them?







The Racetrack

Nestled in a remote valley between the Cottonwood and Last Chance Ranges, the Racetrack is a place of stunning beauty and mystery. The Racetrack is a playa--a dry lakebed--best known for it?s strange moving rocks. 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.

http://www.nps.gov/deva/planyourvisit/the-racetrack.htm

edit typo

[tabatha]

1. Could overnight dew make the surface slippery enough that they

slide down any decline. The surface looks pretty smooth.

[Tace]

5. From The Story:

A research project has suggested 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.

[tabatha]

17. I did not read the story.

[WillParkinson]

2. Very neat...

And also quite cool. Thank you!

[xxqqqzme]

3. It gets too hot there even for rocks,

They're looking for shade.

[Tace]

4. Maybe Tectonic Resonance?

Tectonic vibrations might cause that.

[Auggie]

6. Their patterns are the same too.

Fascinating...

[dysfunctional press]

7. why doesn't someone just set up a camera to find out?

:shrug:

the moisture and wind thing seems the most likely

[JuniperLea]

9. Some of those rocks are the size of a VW Bug...

There are wind velocity histories for the area online... I don't think the wind gets fast enough to move a VW... and if the wind is blowing that hard, good luck on any kind of heavy dew being there. It's really very puzzling, and extremely interesting!

[Xithras]

15. That's not true.

There are certainly large rocks on the playa at the base of the hill along the southern edge, but they don't move. Most of the moving stones are about the size of your fist, with a few larger ones up to the size of a basketball. I saw no moving stones there larger than about 12 inches.

[JuniperLea]

18. They have been recorded... yes, it is true...

Just because you haven't seen one... they are found to be 700 lbs and even larger. I have a picture of a couple of kids on top of one, with the trail off to the side... will look around for it... it's been years since I've seen it.

Here is a 700 lb rock...

[Xithras]

23. I wandered around there a half day, and it's easy to see them all.

The playa is totally flat, the air is clear, and the whole thing is only about 1 mile by 2 miles long (and all of the rocks are in the southern third). You can easily take in the ENTIRE playa from any point along its perimiter. It would be impossible to miss sliding stones the size of a small car...if there were any, we'd have seen them. Most of the stones are in a single area 3/4's of a mile wide, by about 2000 feet long.

I suspect that any picture you saw was either faked (vandals occasionally cut fake traces in the dirt to stage photos...when they're not stealing the stones outright), or was of people on top of one of the larger boulders at the southern edge of the playa. All of the rocks on the playa tumbled off a steep cliff at the playa's southern edge. There are a number of very large boulders (including many the size of Volkswagens) at that edge of the playa, but none of them has moved a millimeter since tumbling down the cliff face.

[JuniperLea]

26. It was a picture I took... in 1985... no fake by any stretch...

I've been there may times, the first time in 1972, and I've been back several times with Scouts (I was Cubmaster) and on family outings. I'm well versed in the area.

And the one picture I posted here of the 700 lb rock is well documented.

[petronius]

33. Well, there's the answer - the woman with the GPS is pushing them with her feet

:)

I don't think it's a stretch for the wind to push a 700 pound rock, so long as the surface is slick enough. The trick would be getting enough water under the rock to get it started...

[JuniperLea]

34. Now that is a good place to start a serious ponder!

Good thought... getting the water under there... and enough of it to slick up the surface, but not so much as to disturb the cracks in the mud. Note how you can see the cracks in the trails of the rocks.

[dysfunctional press]

31. that's why they should set up something to monitor it.

and get an answer.

[JuniperLea]

32. I agree...

We could learn something very useful in the process of solving an age old mystery!

I don't think there is anything "woo woo" about this... but it is yet another example of how the unknown freaks people out. I'm very sure there is a scientific explanation for this, and I'm equally sure we're completely clueless on the issue. Only a long-term monitoring study would shed any light.

[JuniperLea]

8. This is an awesome mystery!

Remember, it's a dry lake bed... flat as flat can get... and it's very dry out there... I love this stuff!

[Stuckinthebush]

10. Ghosts

Gotta be ghosts.

BOO!

:D

[JuniperLea]

11. That would be very cool!

I wish!

[Buzz Clik]

12. It's clearly supernatural. They need to call those guys who hunt ghosts.

"Make yourself known to us! Make that sound again."

[Liberal In Texas]

13. This mystery has been around quite awhile, best theory, IIRC is that when it gets

wet the wind blows them on the slippery mud.

[Xithras]

16. The wind is the most popular theory, but there's a new one that may answer it once and for all.

Someone did finally make it out there during the winter one or two years ago, and discovered that the southern end of the playa can sometimes get a couple inches of standing water on it. It didn't take long for someone to look at the weather data and realize that it sometimes freezes out there in midwinter.

The new theory is that, following particularly cold storms, ice may form on top of the inch or two of water on the playa. If the wind picks up, it pushes these small sheets of ice along the top of the water. If the ice sheet bumps a smooth rock sitting in a slick spot, there might be enough enery to push the rock some distance.

This is a fairly recent theory and still isn't the "official" explanation, but it makes a hell of a lot of sense and actually solves some physics problems that exist with the old direct-wind theory (which requires surface winds up to 80MPH to get the rocks moving, and winds that high are exceedingly rare in the Mojave).

[JuniperLea]

19. That doesn't explain the movement of 700 lb rocks like this...

And they have been known to flip over, so the track left changes in depth, width, and stripe.

[Xithras]

24. Sure it does.

The same way a 50lb cloth can move a 5000lb boat. The surface area of a moving ice sheet, even a thin one, would permit it to exert an enormous amount of energy on anything it bumped into. The large surface would catch the wind and the driven water and provide the ice sheet with a great deal of energy.

Couple that with a surface that gets as slick as oil when properly wet, and you have a simple mechanism for moving anything not anchored down. The rocks glide over the mud the same way a heavy curling stone glides over the ice (which may be a good analogy, since the possibility of frozen mud also exists).

[JuniperLea]

28. If you read the studies carefully...

You'll see a lot of words like "may" and "would" and "possibly." There is much argument about the wind/ice theory because of the cracks in the mud surface of the dry lake, and how they are still visible in the trails left by the rocks. Several researchers have tried moving (by shoving) rocks around while the thin ice is present, and it obliterates the original cracks in the mud. Most researchers say we won't know for certain until someone actually catches and records movement.

[Xithras]

14. I've been out there, and it's very cool (and very hot)

Getting there requires a long drive down a poorly maintained dirt road. The park service leaves the road poorly maintained (and poorly unmarked) to discourage too many people from heading out there. There are no RV's or Priuses in the Racetrack Valley. They say that the road requires a large 4 wheel drive, but my Subaru had no problems getting there. I wouldn't try it in any 2 wheel drive vehicle though.

There's no real mystery about the rocks to anyone who has been out there. The surface of the lake is covered by a rock hard fine-clay/salt soil, and it takes nothing more than a spit test to verify how slippery it gets when wet. If you flip over any of the sliding rocks, you'll notice one common feature...they're all smooth. In fact, if you visit the southernmost edge of the playa where the rocks tumble down from the cliff above, you'll find thousands of stones with rough faces that haven't moved a millimeter. Also, you'll notice that a couple of large dry washes dump into that end of the playa.

So what you have is this...during the occasional storm, water rushes onto the playa from the washes but isn't rapidly absorbed because the surface is so hard. That surface becomes very slick. If the wind is blowing just right (south to north, inline with the valley the playa is located in), the wind speeds get high enough to get the rocks moving and they slide until they catch a crack or the wind dies down.

The other thing you learn, when you go out there, is that only a few have moved any real distance at all. Most of them have only moved a few feet, or even just a few inches. The rocks that race thousands of feet across the playa are the rare exceptions and aren't the norm.

I should also mention that I went in early April, and the temps were in the 90's when I was out there. I was told that the area is practically unreachable in midsummer when temperatures on the playa can exceed 120 degrees. The reason nobody has SEEN these move is that the area can really only be safely visited for a few months each year. In the summer it's too hot to do much of anything in the area, and in the winter the entire valley is closed because the road crosses dozens of unimproved and unbridged washes on the way in. Outside of a pair of narrow windows in spring and fall, the area is pretty well devoid of humans. The day I went out there, there was only one other person on the entire playa (a nature photographer from France, who I had some fascinating discussions with as we ate lunch on the rocks).

[Duer 157099]

20. I've been out there too, agree about the roads

It was over a decade ago, but I recall the roads not being particularly fun to be on, especially the one leading out the west side :shudder:

[JuniperLea]

21. Trials bikes are the way to go...

They are like a cross between mountain goats and camels... they can climb anything and go on and on for the longest time on one small tank of gas.

[hunter]

22. An old two wheel drive VW van will make it out there too...

...with a little bit of persistence and ingenuity. Light car, high clearance, but NO AIR CONDITIONING.

Or a plain little Toyota "pre-steroid look" pickup truck.

Bring lots of water and shade cloth.

I still haven't convinced my wife to go. It's called "Death Valley" and that's plenty enough advice for her: she'd rather not.

[ThomWV]

30. I love this answer

It is factual, its is personal, and its entertaining. No UFOs involved, no perpetual motion machines, no acts of god. How refreshing.

[Orsino]

25. Invisible hand of the market. n/t

[proteus_lives]

27. Obviously Jesus is screwing with us.

He's a got a lot of time to kill in heaven.

[LWolf]

29. I like the ice theory.

My one trip to death valley was for 5 days, by myself, during spring break. It was the best year for wildflowers in a century (in the 90s,) and I enjoyed every minute. The rocks were cool, along with every thing else. The best part, though, was not the specific spots for sight seeing, but finding a little canyon at the edges to hike through for the day. Moving slowly, alone, and spending plenty of time sitting still, there was more wildlife to observe in the "barren" death valley than you'd credit.