Sliding Rocks Bemuse Scientists

An anonymous reader writes "Scientists can't figure out why these rocks — weighing up to several hundred pounds each — slide across a dry lake bed. The leading theory proposes that wind moves the rocks after a rain when the lake bed consists of soft and very slippery mud.

no buildup in front

[egburr]

In all those pictures, I don't see any buildup of dust in front of the rocks, though there is plenty on the sides of the paths. Usually, when I push something through the dirt/mud/snow/whatever, I end up with a good buildup in front, too. I wonder where that has gone.

Re:Ice Sheet

[mpathetiq]

From TFA:

Some researchers have found highly congruent trails on multiple rocks that strongly support this movement theory. However, the transport of a large ice sheet might be expected to mark the playa surface in other ways - these marks have not been found.

Other researchers experimented with stakes that would be disturbed by ice sheets. The rocks moved without disturbing the stakes. The evidence for ice-sheet transport is not consistent.

Re:It's a Horta!

[Anonymous Coward]

Oh. So the movements of the rocks have to do with Horta culture.

You know, TFA mentions they experimented with stakes to test the "ice sheet" theory. I have an idea.

Instead of testing individual theories by leaving stakes sitting around, how about getting a definite answer by leaving a webcam?

Re:Begs the question

[Maint_Pgmr_3]

I agree, if "they" [USGS] can put spiders on MT ST Helens to see how the dome is growing and moving, you would think that someone could tape a small GPS on the rock. Duct tape shouldn't change the movement by much.

better yet, put a small weather station, ala north pole, on a sled and leave it in the middle of the playa and see what the weather conditions are and when it moves. 12 volt battery and an automotive condenser should discourage people from disturbing the sled.

Re:Begs the question

[Bob(TM)]

Yeah, but ... how you gonna keep the webcam from sliding? :)

Re:Mark Newman Poster

[stoolpigeon]

In the desert the ground is really, really hard. It is completely plausible that a thin layer on the top could be slimy mud, while hard clay lies beneath.
 
I don't think you appreciate how remote this site is and what an effort it would be to pull off something like that. I really don't think it is someone messing around or that the wind theory is as unlikely as you think.

Re:Begs the question

[fbjon]

It still seems strange. The place is really dry, meaning there's lots of sun. Just make a small package with a GPS receiver, some simple weather instruments, a radio uplink to a nearby relay, a small camera and a solar panel with battery. If the GPS detects any movement, or the weather instruments detect any drastic changes, turn on all other stuff and start piping data to the relay, which passes it on by whatever means.

If anybody steals the package, it'll sound an alert and record who took it, and where they're taking it.

Re:Amazing how no-one bothers to actually CHECK.

[Ambiguous Coward]

Come now...while I agree that the video is (mildly) interesting, it is not what you claim. But beside that, the article doesn't say "there's no possible explanation" at all. In fact, the article presents at least a couple possible explanations. In fact, and I say this with every ounce of *gasp* I can muster, the article presents an explanation for the moving rocks that is identical to the one presented in the video! Did you happen to read the article? You ought to. It's relevant to this discussion.

-G

Re:It's a Horta!

[GeekZilla]

"Instead of testing individual theories by leaving stakes sitting around, how about getting a definite answer by leaving a webcam?"

THANK YOU! Oh my god! And these are actually "scientists" studying these things? Sure, maybe hooking up to the internet is a little dicey in Death Valley, but there are other ways. They need some college kid hyped up on caffeine to wire together a solar-powered, weather proof DVR and finally solve this mystery. I mean, come on! How long have we known about these tracks? Decades?

Sorry, I tend to get a little touchy when there is a mystery and 1) the experiment that could solve it is REALLY simple and 2) The mystery has been around for years. I think it would make a good thesis...no, I think it would make a decent term paper for some high-school senior interested in Geology.

Re:It's a Horta!

[camperdave]

Plant a camera out there for a year, take a snapshot every minute (or use motion detection), collect weather data (humidity, dew point, temperature, evaportion rates, wind speed/dir) and corrolate that to the time-series snap shots.

... and hopefully you'll be able to find out who made off with your expensive camera.

Re:Amazing how no-one bothers to actually CHECK.

[evanbd]

Did you watch the video carefully? They offer a very authoritative sounding explanation of the water / ice theory presented as one option in the article, but don't actually capture rocks in motion on film. There's water moving, and some sort of foam on top of the water, but that's about it. As the original article says, there's lots of evidence in favor of this theory, but also evidence against it being that simple -- like experiments involving undisturbed stakes and such. As far as I can tell, that seems to be a piece of the explanation, but not the whole explanation.

Re:It's a Horta!

[dfn_deux]

The Horta culture is really complex like that ;)

Re:It's a Horta!

[jamstar7]

So many great setups, so few modpoints.

Re:Mark Newman Poster

[Roger W Moore]

Problem is that storms come up rarely but suddenly there (usually) and it takes almost two hours to get to the Racetrack from the nearest paved road - three hours from the Death Valley visitor's center - and if you get out there before a storm, there's no guarantee that even a very capable 4x4 will get you back afterwards.

Isn't this what remote camera's were invented for? I doubt this location is so remote that there isn't some way to link it up or at least to store the data and then periodically retrieve it. The question is have these rocks moved recently or is this a rare (i.e. once/century say) type occurance?

Re:It's a Horta!

[Walkingshark]

Why not grab a 3m x 3m x 10cm sample of the surface, take it to a lab, hose it down, drop a rock on it, and turn on a fan?