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racetrack playa, 3.23.05.

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racetrack playa, 3.23.05.
Rocks like this at the racetrack playa are deposited at the playa edge by adjacent slopes and cliffs, and then they raft around for quite a while leaving winding trails along their path. No one has ever witnessed the rocks in motion, and surprisingly, the general trend of movement is slightly uphill.

One theory on what makes them move such great distances is that they are blown by wind and move when the playa is wet and slippery. Another theory is that their movement is aided by an ice surface created when the wet playa freezes on cold nights. These are now challenged by an "ice-raft" theory, see: http://blogs.agu.org/landslideblog/2013/05/17/was-the-bingham-canyon-landslide-the-largest-ever-non-volcanic-landslide-in-north-america/


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Voted 10/10

How did that rock make it there ?


Posted Mar 27, 2005 5:02 am

FelsbergRe: Mysterious


Hasn't voted

well these rocks are presumably deposited on the edge of the playa by adjacent slopes and cliffs, and then they raft around for quite a while. One theory on what makes them move such great distances is that they are blown by wind and move when the playa is wet and slippery. Another theory is that their movement is aided by an ice surface created when the wet playa freezes on cold nights. The elevation here is fairly high (~4000 ft) so the ice theory seems the most plausible. As far as I know it remains an unsolved natural mystery.
Posted Mar 27, 2005 1:51 pm

CoraxRe: Mysterious


Voted 10/10

Interesting theories and a good shot.

I like photos that make you think and this one leaves no one untouched i would say.
Posted Apr 2, 2005 2:06 am

Mark DoironMother Nature ...

Mark Doiron

Voted 10/10

Mother Nature is full of surprises and mysteries, isn't she? Thanks for sharing the image and theories. By the way: Did you happen to drive Titus Canyon while in Death Valley? We (my son and I) did a couple years ago; awesome experience!
Posted Mar 31, 2006 7:29 pm

AspenMY ROCK!!!


Hasn't voted

Heeeey!! THAT's my long lost pet rock!! His name is "Phil" Thanks for finding him!

Posted May 11, 2006 3:57 am

FelsbergRe: MY ROCK!!!


Hasn't voted

ha! they are actually all somebody's pet rocks now, they're all named:
my guess is that this rock is called "stacy," you can see where she was in '96 and go visit her...
Posted May 11, 2006 5:34 am

AspenEveryone's Rock


Hasn't voted

Hey I noticed that all the rocks have girl's names. I learn something new everyday! Yaaah!!

Posted May 11, 2006 1:52 pm



Hasn't voted

It is kind of hard to get a sense of how big the rock is from this picture- how big is it?
Posted May 23, 2006 11:36 pm

FelsbergRe: perspective


Hasn't voted

as I recall, its probably about 18 inches across
Posted May 24, 2006 6:03 am



Voted 10/10

...misterious place but beautiful and interesting phenomenon with the rocks.
Posted May 24, 2006 10:35 am

supermarmoti'm going with the ice theory


Voted 10/10

while it's hard to judge from a photo, the ice theory seems more plausible when you consider the 'front' of the rock.
if the rock had moved across a muddy surface there would likely be evidence of at least a minor ridge of mud that had been pushed along in front of the rock, much like the ridges along the sides of the track (unless it popped a wheelie:)

now consider the effect of the rock sliding across a frozen surface: the rock would put pressure on the ice and the ice would presumably bend under the weight without breaking continuity on the surface (otherwise the rock would likely be stopped by ice buildup). the trick is that ice buffer would allow the rock to move with minimal impact on the playa directly in front of it; an ice layer would contain and compress the mud as the rock passed.
as to the uphill trend: very likely an illusion, unless the wind there is enough to overcome some serious m*g*sin(theta). if i ever go there i'll make sure and bring a soccer ball and do a roll test:)

thanks for the fun riddle.

Posted Jul 22, 2006 7:33 am

FelsbergRe: i'm going with the ice theory


Hasn't voted

spoken like a scientist. i think you raise a valid point about the ice layer and levee formation, but as I recall in many cases there were mud accumulations in front of the rocks as well... I agree with you though that the ice theory seems to fit with the morphology of the deposits. cheers - jm
Posted Jul 22, 2006 3:57 pm

Aaron JohnsonAmazing!

Aaron Johnson

Hasn't voted

Who'da thought! Moving rocks...with minds of their own! Perhaps in another reality, they are living things. Something we'll never know. Thanks for insight into this bizarre phenomenon.
Posted Feb 14, 2007 11:47 pm



Voted 10/10

I'll be there's an alien theory as well?! Maybe elves or gnomes? Ha!

Cool picture...very interesting!
Posted Feb 19, 2007 4:51 pm

icypeakThat's amazing


Voted 10/10

Something for the X Files if you ask me!!
Posted Aug 30, 2007 7:01 pm

bongsunkeeit`s really amezin!


Voted 10/10

wonder, i wonder.....
Posted Sep 3, 2007 5:47 pm



Voted 10/10

I have the exact same shot!
Posted Sep 13, 2007 12:57 am

SteveOsI'm speachless


Voted 10/10

What an awesome phenomenon!
Posted Dec 20, 2007 4:05 pm

IalewisAnother theory:


Voted 10/10

Both the rock and the mud are moving downhill, but the mud moves faster. When the playa heats up, the surface melts and becomes semi-fluid. The rock is in contact with firmer ground below and moves at a slower rate than the surrounding mud. Thus, the rock does move, but the mud moves faster, hence the track. Great photo!
Posted Jan 30, 2008 4:27 pm

nartrebRe: Another theory:


Hasn't voted

Wrong for two reasons:
1) the rocks don't move in a fixed direction, so they can't be going downhill.
See the track left by one rock.

2) Look at the trail: totally smooth in the middle (quite different from surrounding mud which is cracked and pillowed), with ridges along the edges and in front of the rock. If the mud were liquid enough to flow around independently, it would be liquid enough not to leave those trail features.
Posted Jan 30, 2008 4:52 pm

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Image Data
FelsbergSubmitted by Felsberg
on Mar 26, 2005 11:02 pm

Image ID: 97292
Hits: 7732 
Lat/Lon: 36.66894°N / 117.55957°W
Object Title: racetrack playa, 3.23.05.