Sliding Rocks Bemuse Scientists 433
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.
Mark Newman Poster (Score:5, Informative)
Re:Mark Newman Poster (Score:5, Informative)
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It's very easy to imagine that if the ground had been muddy, the wind could slide the rocks around.
There are few sights as graceful as the majestic stoneships with their rocky sails gliding across the bounding main.
OK, I can possibly imagine storm winds so ferocious that they can drag rocks across a rough surface. I just can't imagine said surface being neatly lined and clean-edged afterward. If the mud were soft enough for the rocks to move across it easily, wouldn't it be prone to the soil equivalent of whitecaps with little ripples across it?
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But no, really, I was at the Racetrack playa in Death Valley National Park. I'd post pictures, but the ones in TFA cover it pretty well. Although I do have a nice close-up of the ground texture.
Re:Mark Newman Poster (Score:5, Insightful)
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.
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Indeed.
When my heavy beer glass gets a tiny bit of water between it and the hard table, it starts sliding around all by itself, with no wind at all. I can imagine that these stones slide similarly.
Re:Mark Newman Poster (Score:5, Interesting)
The toilet seat lid was covered in a fine layer of condensation from the bath water at the time.
I'm betting if the stones are cooled way down to almost freezing by the wind, or maybe frozen overnight and still cold when the rains hit, and the top surface of the mud turns into a slurry of fine particles, the stone will move around all on its own just like my cold glass of water on a fine layer of condensation.
Either that or space aliens.
Another theory (Score:3, Interesting)
Perhaps, when the ground is wet, there's a mud layer slightly beneath the surface that becomes fluid. Then, tidal foces make the surface to move up and down creating waves. The waves migh be very low amplitude (a few cm could be enough) and low speed/frequency, but enough to make the rocks slowly slide on the dry (or slightly moist) surface.
Does it sound plausible?
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When the glass is put down, if the water seal forms before the glass has fully contacted the surface, the air pressure will lift the glass as it evens out the pressure on the air cushion. This will cause it to be riding on an air bearing, and slide very easily.
Usually it will only go until the water seal is broken, releasing the air pressure that for
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Well, you know of course that why the famous experiment with marbles on a smooth surface works. It's well known that any object on a relatively frictionless surface will slowly drift to the West because of the Earth's rotation. This is why that old design for "air hockey" was unfeasible. That's why marbles on balanced glass
Re:Mark Newman Poster (Score:5, Interesting)
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.
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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 retriev
Re:Mark Newman Poster (Score:5, Funny)
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So ride the rocks!
Re:Mark Newman Poster (Score:4, Funny)
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In Death Valley? They'll remember your face and tomorrow you'll end up driving an extra 50 miles for lunch.
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It's a Horta! (Score:5, Funny)
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Re:It's a Horta! (Score:4, Funny)
Re:It's a Horta! (Score:5, Funny)
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Re:It's a Horta! (Score:5, Funny)
Thus, you can lead a Horta water, but you can't make it drink.
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Re:It's a Horta! (Score:4, Funny)
I wonder if they can just "tag" the rocks like they do with sharks, elephants, walruses, etc. I mean, I know the rocks don't have ears or collars, but there has to be a way.
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* The rocks don't move very often -- typically once every two or three years.
* Cheap webcams have only been around for a few years, and I don't know if there have been any movement episodes during this time.
* It's an incredibly hostile environment for electronic equipment: surface temperatures of 150+ degrees F during summer days, temperatures below zero F during winter nights, violent rainstorms, and intense direct sunlight.
* There is no electricity. There is
Re:It's a Horta! (Score:4, Informative)
From a dependable source [pbs.org]:
If you've never been to Death Valley in the summer, you should give it a try. If you're from a mild climate, I suggest March instead; the regular 90 degree temperatures before April has shown it's face will give you a little idea of the radical heat that this region experiences.
*The Racetrack and Badwater are both below sea level, so you'd need to get up to at least 240f to boil water.
Re:It's a Horta! (Score:4, Funny)
Obvious Answer!! (Score:4, Funny)
IT'S ALIENS GUYS!! RUN FOR YOUR LIVES!!
So this is... (Score:5, Funny)
...nature's version of desert curling?
I think (Score:2)
Re:Global Warming (Score:5, Funny)
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1:But the Teutonic order wasn't formed till the end of the 12th century!
2: Man i really am glad science moved away from that medieval idea of plate tectonics.
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Answer on page 42 ... (Score:5, Interesting)
Quote: "Research of the Racetrack has continued. In the April 1997 GPS World, Paula Messina, Phil Stoffer and Keith C. Clarke reported a GPS study they conducted of the Racetrack. In ten days of intense field work they mapped every featured of the playa using differential GPS to produce, "the first-ever, complete, georeferenced, submeter-resolution map of the wandering rocks." (Messina, 1997, p. 42)"
http://sophia.smith.edu/~lfletche/deathvalley.html [smith.edu]
But it seems they have no real conclusion too.
What about 'The Force"?
CC.
Re:Answer on page 42 ... (Score:5, Funny)
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Begs the question (Score:4, Interesting)
Not even a webcam. (Score:2)
Also, build a rock with different measuring devices in it and see if IT moves.
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The reason is because there is no way to know when these rocks, or which rocks, will move. Since we don't currently know what causes them to move, there is no way to wait for those conditions and then start filming. Even with the best guess (wind + water or ice) you'd still have the multi-choice selection of subjects to choose from.
What would have to be done is to have multiple cameras pointing a
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Not if they come up from behind it or wear a mask. Trust me, if there is something to be stolen, someone will figure a way to do it. Take a look at the houses in Detroit (and other places) which are up for foreclosure. People are stealing the siding off of them to be sold as scrap.
Re:Begs the question (Score:5, Insightful)
If anybody steals the package, it'll sound an alert and record who took it, and where they're taking it.
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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.
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This begs the question, why hasn't someone setup a webcam to record these rock movements and solve this thing once and for all?
Why not just take some water and a fan up to there to test the leading theory. Wet down a patch of ground to get it nice an slippery and then turn on the fan to see if you can blow a rock around. If that fails then go with the webcam.Re: (Score:3, Insightful)
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If necessary, a traffic light [howstuffworks.com] can be added to increase accuracy.
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http://wsu.edu/~brians/errors/begs.html [wsu.edu]
Raises the question != Begs the question.
Isn't it obvious yet? (Score:5, Funny)
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no buildup in front (Score:5, Insightful)
Re:no buildup in front (Score:5, Interesting)
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.
I had to think about this for a second... I think the answer is that if a rock was digging into the mud, you wouldn't have this effect, because of having to shove the mass of the mud. If you look at the pictures, the fronts of a lot of them tend to be sticking up, implying they're "surfing" over the mud.
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Yes I noticed too. I also noticed that the rocks pictured were not random shapes. The front of the rocks looking more like a slidable(?) geometry. Perhaps the rocks are not pushing any mud in front of them but riding over it. Too many ifs. We need some observations.
Obviously mud (Score:2)
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Because there isn't a place windy enough to push a 100 pound rock through a 1/4 inch of mud. SOmething must be lowering the friction AND be thin enough to break.
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Magnetism? (Score:2)
Re:Magnetism? (Score:4, Funny)
Re:Magnetism? (Score:5, Funny)
I am pretty sure ... (Score:5, Funny)
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god doesn't play dice (Score:5, Funny)
One thing I know for sure (Score:5, Funny)
or rather, 100 of them.
I for one (Score:2)
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Its not that hard to figure out! (Score:2, Informative)
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Logic dictates that they'll then only move at night... :-)
FSM (Score:2, Funny)
Skeptoid (Score:2)
Yeah, that or it's space aliens w
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Problem solved (Score:2)
I for one... (Score:2)
Silly scientists... (Score:5, Funny)
Trolls! (Score:2)
duh! (Score:2)
What mystery? (Score:2)
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Tax Dollars at Work! (Score:2)
The rocks are stable... (Score:2)
Runaway solution (Score:2)
One possibilty (Score:5, Interesting)
Hmm (Score:2)
Problem with the ice or even water theory (Score:4, Interesting)
The cracked effect is what you get when muds dries out, the effect is NOT visible in the trails. How can this be IF the rocks moved when the mud was still there? There is a cracked effect in the trail but it is crushed, the effect you would expect if the rocks had been moved AFTER the ripple effect had already started to form, AFTER the mud started to dry or even when it was already dry.
But if the rocks moved on ice then AFTER the ice melted there would be mud, that if dried would show the same pattern all around the newly positioned rock with just the ridges of the trail left. NOT flattened dried mud.
As for purely the wind moving them, how fast do the winds get there anyway? Wind can be extremely powerfull even in areas with lots of obstructions, in open areas, well if it can pick up/move trucks, why not rocks? Far heavier things are lifted up by air alone, how do you think aircraft work?
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Re:Any word on magnetic influence? (Score:4, Funny)
Re:Any word on magnetic influence? (Score:4, Funny)
{rimshot}
Everything must be ruled in or out, but... (Score:3, Informative)
Re:Any word on magnetic influence? I'd guess it isn't wind...are these rocks ferrous? Or...maybe the earth is tilting on its side...weird stuff like that always happens here...I think our perspective of it is just off a bit.
I've camped a few times at Texas Spring campground in Death Valley. Nice place in the right times of the year. One year, however, the wind blew all night at about 40 knots. Nearly took me and my tent away. There are sand dunes to the north of the valley, too. I expect the winds there are more than up to the task of pushing around rocks on moist clay. Perhaps most enigmatic is the question, 'Why don't these larger rocks sink into the mud?' Though with strong enough winds, I imagine they could get a
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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.
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MOD PARENT UP! (Score:2)
I remember this thing from back in '80s and even back then it was obvious that its water+wind+ice that makes the rocks move.
What is next? Channels on Mars?
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-G
Re:Amazing how no-one bothers to actually CHECK. (Score:5, Informative)
And as to the foolishly simple explanation, H.L. Mekcken is quoted to have said, "Every complex problem has a solution that is simple, direct, plausible, and wrong".
Re:Amazing how no-one bothers to actually CHECK. (Score:4, Insightful)
That was Strangely Topical. (Score:4, Funny)
I Require you Rectify this Rankling Repugnance.
Regards,
Ryan