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Sailing Stones of Death Valley


SSilhouette

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http://www.hoaxorfact.com/Science/sailing-and-moving-rocks-and-stones-of-death-valley.html

Sailing and Moving Rocks and Stones of Death Valley

The mysterious moving stones of the packed-mud desert of Death Valley have been a center of scientific controversy for decades. Rocks weighing up to hundreds of pounds have been known to move up to hundreds of yards at a time. Some scientists have proposed that a combination of strong winds and surface ice account for these movements. However, this theory does not explain evidence of different rocks starting side by side and moving at different rates and in disparate directions. Moreover, the physics calculations do not fully support this theory as wind speeds of hundreds of miles per hour would be needed to move some of the stones...

Some people theorize the stones move when ice forms on them and mud underneath in combination with strong winds. Yet some of the stones are hundreds of pounds. The force of wind needed to move them just isn't supported in the weather data.

So what do you think is happening?

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Interesting, the very last line of the article reads...

...Therefore, sliding rocks in Death Valley is a fact that can happen in rarest weather conditions.

Mystery solved. :tu:

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Here you go:

[media=]

[/media]

Wind, water, ice...

..to be precise, in order to move even a very heavy rock, a tiny, tiny force will do the job if you have very slippery mud / ice.

Edited by ChrLzs
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Interesting, the very last line of the article reads...

Mystery solved. :tu:

Not so fast. The trails of some of those hundreds-of-pounds boulders are hundreds of feet long. In order to cause that length of a trail the "rarest of events" would have to be happening quite regularly; which the data does support in the weather reports. Moreover, if that level of wind can move those boulders that far, imagine what it would do to the burms along the edges of those trails? It would erode that sand and blow it away much faster than the boulders themselves. "Wind, water and ice" would take a much quicker toll on the loosely accreted sandy burms around the trail's edges than it would solid rock. Also look at the odd shapes of the rocks. Some are top heavy. Wind at that speed if it was pushing the boulders along would tip them over to bottom heavy eventually. And sharp, erratic twists and turns would be added to the trails. Some of the trails in some pictures I've seen run perpendicular to other ones. With a steady wind in one direction, how is this happening?

Here's a picture of some:

sailingstonesdeathvalley_zps871a38f1.jpg

Edited by SSilhouette
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Not so fast. The trails of some of those hundreds-of-pounds boulders are hundreds of feet long. In order to cause that length of a trail the "rarest of events" would have to be happening quite regularly; which the data does support in the weather reports. Moreover, if that level of wind can move those boulders that far, imagine what it would do to the burms along the edges of those trails? It would erode that sand and blow it away much faster than the boulders themselves. "Wind, water and ice" would take a much quicker toll on the loosely accreted sandy burms around the trail's edges than it would solid rock. Also look at the odd shapes of the rocks. Some are top heavy. Wind at that speed if it was pushing the boulders along would tip them over to bottom heavy eventually. And sharp, erratic twists and turns would be added to the trails. Some of the trails in some pictures I've seen run perpendicular to other ones. With a steady wind in one direction, how is this happening?

Yes it is intrigueing. You might find the research of Dr Messina of particular interest. This is a very good article and proposes yet another element of suprise...

...At an elevation of 3,700 feet, strong winds can rake the playa at 70 miles per hour. But Dr. Messina is quick to point out that sometimes even smaller gusts can set the rocks in motion. The explanation for this lies in her theory, which links wind and water with yet another element: bacteria...

http://www.pbs.org/wnet/nature/episodes/life-in-death-valley/the-mystery-of-the-racing-rocks/5088/

I guess there is such a thing as greasy ice.

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She has found that two components are essential to their movement: wind and water. The fierce winter storms that sweep down from the surrounding mountains carry plenty of both.

The playa surface is made up of very fine clay sediments that become extremely slick when wet. “When you have pliable, wet, frictionless sediments and intense winds blowing through,” offers Dr. Messina, “I think you have the elements to make the rocks move.”

At an elevation of 3,700 feet, strong winds can rake the playa at 70 miles per hour. But Dr. Messina is quick to point out that sometimes even smaller gusts can set the rocks in motion. The explanation for this lies in her theory, which links wind and water with yet another element: bacteria.

After periods of rain, bacteria lying dormant on the playa begin to “come to.” As they grow, long, hair-like filaments develop and cause a slippery film to form on the surface. “Very rough surfaces would require great forces to move the lightest-weight rocks,” she says. “But if the surface is exceptionally smooth, as would be expected from a bio-geologic film, even the heaviest rocks could be propelled by a small shove of the wind. I think of the Racetrack as being coated by Teflon, under those special conditions.”

In science, hypotheses are often based on logic. But over the years, Dr. Messina has discovered that on the Racetrack, logic itself must often be tossed to the wind. “Some of the rocks have done some very unusual things,” she says

I followed your link and got the quote above. The scientist notes that the grains that make up the ground and the trails left behind the rocks are very fine, however, why haven't the strong winds ground those tracks flat as the surrounding terrain? I spent many a year exploring the desert and its features [not there but elsewhere], Features on the ground in sandy areas such as footprints, tire ruts and impressions after strong winds are erased, essentially. Yet what appears to be years worth of track evidence lays there unmolested by the same winds supposedly skidding along boulders some in excess of 100 lbs.

Theories are theories. They don't settle a matter unless the proof is in. Proof would mean camping out there, installing time lapse cameras and filming the movement of the rocks and noting the corresponding conditions. Nobody that I know of has done that yet. It makes me wonder why not?.

Edited by SSilhouette
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I wached a video, maybe one linked here, a year or so ago, that fully recreated an abbreviated example of these things and their path, using a number of different weight and shapes of stones, and to me proved the value of scientific study by bein able to reproduce a long-wondered-about mystery. I personally consider the sailing stone phenomenon now solved, or easily completely solvable, using somewhat varied applications of these same principles, which did indeed focus on the unique wind speed and patterns and temperature and humidity fluctuations.

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I have been to Death Valley and have stood next to those rocks and the trails they leave. The soil there is not fine and silty like most desert soil. The soil is hard packed and also contains salt from when it was a lake. It IS possible for the rocks and boulders to be moved by nature and still have those trails with their berms.

I'm no expert. This is just my observation and 2 cents.

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OK, I just took geology and there is a thing called the hardness-scale. Those rocks score higher and would be more resistant to wind factors than grains of sand accreted together.

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SSilhouette, if you spent all this time in the desert collating and checking this data about whether trails might be erased by the next rainfall, can I see the pics and original notes you took? And what does the hardness scale have to do with this, if we are talking about mud and ice being slippery, salt (partially/fully) dissolving, etc?

Being an investigator is *not* about making unsubstantiated claims.

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SSilhouette, if you spent all this time in the desert collating and checking this data about whether trails might be erased by the next rainfall, can I see the pics and original notes you took? And what does the hardness scale have to do with this, if we are talking about mud and ice being slippery, salt (partially/fully) dissolving, etc?

Being an investigator is *not* about making unsubstantiated claims.

while theories are being thrown around I can come up with my own. I roamed the desert as a child. Wasn't doing research "officially" then. Only noticed what my five senses were telling me. I've seen rutted tracks get erased by wicked winds and sandstorms. The hardness scale would show how resistant a given substance is to wind erosion. Accreted sand in dried mud is less hard than igneous or metamophic rock [which from the looks of the stones is what we're dealing with]. So if the winds were blowing hard enough to move 100+ lb boulders around, you'd think those tracks would be taking a beating too.

And without any notes at all, you know that's a solid point and observation. It could be that there's a viable and solid natural explanation. I'm just not buying the "they're getting blown around by the wind" theory. Maybe ground heaving? Something like that?

Edited by SSilhouette
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  • 2 months later...
 

here is another site about a study done on the sailing stones ...

https://scripps.ucsd...tion-first-time

in December 2013, Norris and co-author and cousin Jim Norris arrived in Death Valley to discover that the playa was covered with a pond of water seven centimeters (three inches) deep. Shortly after, the rocks began moving.

“Science sometimes has an element of luck,” Richard Norris said. “We expected to wait five or ten years without anything moving, but only two years into the project, we just happened to be there at the right time to see it happen in person.”

Their observations show that moving the rocks requires a rare combination of events. First, the playa fills with water, which must be deep enough to form floating ice during cold winter nights but shallow enough to expose the rocks. As nighttime temperatures plummet, the pond freezes to form thin sheets of “windowpane” ice, which must be thin enough to move freely but thick enough to maintain strength. On sunny days, the ice begins to melt and break up into large floating panels, which light winds drive across the playa, pushing rocks in front of them and leaving trails in the soft mud below the surface.

“On Dec. 21, 2013, ice breakup happened just around noon, with popping and cracking sounds coming from all over the frozen pond surface,” said Richard Norris. “I said to Jim, ‘This is it!’”

These observations upended previous theories that had proposed hurricane-force winds, dust devils, slick algal films, or thick sheets of ice as likely contributors to rock motion. Instead, rocks moved under light winds of about 3-5 meters per second (10 miles per hour) and were driven by ice less than 3-5 millimeters (0.25 inches) thick, a measure too thin to grip large rocks and lift them off the playa, which several papers had proposed as a mechanism to reduce friction. Further, the rocks moved only a few inches per second (2-6 meters per minute), a speed that is almost imperceptible at a distance and without stationary reference points.

Edited by lightly
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