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posted by martyb on Wednesday September 29, @07:39PM   Printer-friendly
from the can-you-top-this? dept.

Physicists may have cracked the case of “Zen” stones balanced on ice pedestals:

Visit the Small Sea of Lake Baikal in Russia during the winter and you'll likely see an unusual phenomenon: a flat rock balanced on a thin pedestal of ice, akin to stacking Zen stones common to Japanese gardens. The phenomenon is sometimes called a Baikal Zen formation. The typical explanation for how these formations occur is that the rock catches light (and heat) from the Sun and this melts the ice underneath until just a thin pedestal remains to support it. The water under the rock refreezes at night, and it's been suggested that wind may also be a factor.

Now, two French physicists believe they have solved the mystery of how these structures form, according to a new paper published in the Proceedings of the National Academy of Sciences—and their solution has nothing to do with the thermal conduction of the stone. Rather, they attribute the formation to a phenomenon known as sublimation, whereby snow or ice evaporates directly into vapor without passing through a water phase. Specifically, the shade provided by the stone hinders the sublimation rates of the surrounding ice in its vicinity, while the ice further away sublimates at a faster rate.

Many similar formations occur naturally in nature, such as hoodoos (tall, spindly structures that form over millions of years within sedimentary rock), mushroom rocks or rock pedestals (the base has been eroded by strong dusty winds), and glacier tables (a large stone sitting precariously on top of a narrow pedestal of ice). But the underlying mechanisms by which they form can be very different.


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  • (Score: 1, Informative) by Anonymous Coward on Wednesday September 29, @11:02PM (1 child)

    by Anonymous Coward on Wednesday September 29, @11:02PM (#1182966)

    When I was a kid (pre Internet) there was plenty of time to go outside and daydream. There were a few stream banks or road cuts where I observed that there would often be rocks perched on a column of mud. The soil was thick clay. I kind of assumed that compressed clay didn't dissolve as much as uncompressed clay, and also the rocks sheltered the underlying soil from direct rain. They were still doomed to fall, it was just going to take more time. The columns never got very high, but they were noticeable. I might have guessed that compressed ice was somehow stronger than uncompressed ice too.

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  • (Score: 2, Interesting) by Anonymous Coward on Thursday September 30, @01:28PM

    by Anonymous Coward on Thursday September 30, @01:28PM (#1183096)

    I would say that, in your case, the compression seems more likely.

    It seems reasonable to assume (and then science!) that the ice is affected by that as well to some degree.

    That said, shade was the first thing that I thought of, though admittedly I immediately second guessed myself as rocks are darker than ice and so I figured the "shade" would actually make for more melting.

    This is why science has wild speculation as the second step (immediately after the WTF?! step), but conclusions aren't reached until you test them.

    Science:
    WTF? --wild speculation-> hypothesis --testing-> conclusion --adversarial testing-> theory