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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.

12 of 433 comments (clear)

  1. Mark Newman Poster by stoolpigeon · · Score: 5, Informative

    Mark Newman has a very nice sliding rock poster with a good shot of rock and trail in a variety of sizes.

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    It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
    1. Re:Mark Newman Poster by An+ominous+Cow+art · · Score: 4, Informative

      I was there in August this year, and it was quite windy. It's very easy to imagine that if the ground had been muddy, the wind could slide the rocks around.

    2. Re:Mark Newman Poster by ChameleonDave · · Score: 2, Informative

      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.

    3. Re:Mark Newman Poster by Mantis8 · · Score: 1, Informative

      Here's another pic of a sliding rock: http://www.pbase.com/devonshire/image/76469804

    4. Re:Mark Newman Poster by Linux_Bastard · · Score: 3, Informative

      What is happening there is that the cohesive water is acting as a flexible seal around the bottom of your glass, and it is resting on a cushion of trapped air.

      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 forms the cushion. If the surface is moist enough, the cohesive water can renew the seal as it glides.

      If you try this with a very flat, nearly level surface and a glass with a concave bottom you can get good results.
      Hot liquids can actually expand the air under them and suddenly lift up and slide.

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      F X=0:1:9999 F D=2:1 Q:((X>2)&(X#D=0)!((D>X/2)&(X'=1))) I D>(X/2) W:$X>75 ! W X,?$X+5-$l(X) Q
  2. Its not that hard to figure out! by Henneshoe · · Score: 2, Informative

    If there is really this much interest in figuring out how the rocks move, its pretty easy to do. Mount a solar powered camera with a motion detector. If the rock moves start shooting. If you really want to get fancy, you could do a continual time lapse to catch the movement if it is too slow for the motion detector. I think they do this kinda thing when you want to get pictures of wild animals in there natural habitat and the cameras are avaliable at your nearest outdoor outfitter.

  3. Everything must be ruled in or out, but... by ackthpt · · Score: 2, 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 move on again.

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    A feeling of having made the same mistake before: Deja Foobar
  4. Re:Amazing how no-one bothers to actually CHECK. by DigitalCrackPipe · · Score: 4, Informative

    In true /. form, you either failed to RTFA or to WTFV, as the video clearly does not show the rocks moving. It shows water and miscelaneous floating scum moving, and posits the same theories as in the article (just claiming them to have been proven).

    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".

  5. Re:Begs the question by orclevegam · · Score: 2, Informative
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    Curiosity was framed, Ignorance killed the cat.
  6. Re:It's a Horta! by Carnildo · · Score: 2, Informative

    There are a number of reasons why they haven't:
    * 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 no internet service. There is no wireless phone service. During the rainstorms when the rocks are expected to be moving, there is no satellite service.
    * There's the ever-present risk of theft.

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    "They redundantly repeated themselves over and over again incessantly without end ad infinitum" -- ibid.
  7. Re:Begs the question by Random+Destruction · · Score: 2, Informative

    I'm siding with Paul Brians on this one.
    http://wsu.edu/~brians/errors/begs.html

    Raises the question != Begs the question.

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    :x
  8. Re:It's a Horta! by vought · · Score: 3, Informative

    Given the hottest temperature ever recorded in the United States is 56.7 degrees celsius (134.1 degrees fahrenheit) I find it impossible to believe this small part of America regularly gets temperatures of above 65.6 degrees celsius (150F). A friendly nitpick: surface temperatures on the desert floor - even on light-colored surfaces like the Racetrack - can often rise above 200 degrees F. Note that the ambient temperature may be far cooler than the ground surface.

    From a dependable source:

    In the heat of summer, Death Valley roasts in temperatures greater than 120 degrees, cool when compared with the surface temperature of the salt pan. "The ground temperature gets to over 200 degrees [f] at some points here," says Dr. Douglas. I'd wager that the surface temperatures at the Racetrack in early afternoon during high summer range above the boiling point of water at sea level*, since the racetrack's playa is lower and darker than the salt pan at Badwater. In other words, don't fall; you'll skin and burn your knees.

    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.