Mystery of the sailing stones of Death Valley solved – 'climate change' immediately blamed for no good reason

Photo by Scott Beckner via Flickr CC license

Photo by Scott Beckner via Flickr CC license

The discovery of the mechanism that causes “sailing stones” in Death Valley is actually a great example of observational science, it just too bad these scientists ruined the announcement by blaming “climate change” instead of the things that ACTUALLY drive the flooding of the playa, like regional weather patterns, the PDO, and ENSO. Watch the video.

Here are frames of that video, with annotations, click for a very large image:

sailing rocks2_plosoneHere is how they describe it, from the Scripps Oceanograpgy website:

Racetrack Playa is home to an enduring Death Valley mystery. Littered across the surface of this dry lake, also called a “playa,” are hundreds of rocks – some weighing as much as 320 kilograms (700 pounds) – that seem to have been dragged across the ground, leaving synchronized trails that can stretch for hundreds of meters.

What powerful force could be moving them? Researchers have investigated this question since the 1940s, but no one has seen the process in action – until now.

In a paper published in the journal PLOS ONE on Aug. 27, a team led by Scripps Institution of Oceanography, UC San Diego, paleobiologist Richard Norris reports on first-hand observations of the phenomenon.

Because the stones can sit for a decade or more without moving, the researchers did not originally expect to see motion in person. Instead, they decided to monitor the rocks remotely by installing a high-resolution weather station capable of measuring gusts to one-second intervals and fitting 15 rocks with custom-built, motion-activated GPS units. (The National Park Service would not let them use native rocks, so they brought in similar rocks from an outside source.) The experiment was set up in winter 2011 with permission of the Park Service. Then – in what Ralph Lorenz of the Applied Physics Laboratory at the Johns Hopkins University, one of the paper’s authors, suspected would be  “the most boring experiment ever” – they waited for something to happen.

But 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.

“It’s possible that tourists have actually seen this happening without realizing it,” said Jim Norris of the engineering firm Interwoof in Santa Barbara. “It is really tough to gauge that a rock is in motion if all the rocks around it are also moving.”

Individual rocks remained in motion for anywhere from a few seconds to 16 minutes. In one event, the researchers observed rocks three football fields apart began moving simultaneously and traveled over 60 meters (200 feet) before stopping. Rocks often moved multiple times before reaching their final resting place. The researchers also observed rock-less trails formed by grounding ice panels – features that the Park Service had previously suspected were the result of tourists stealing rocks.

“The last suspected movement was in 2006, and so rocks may move only about one millionth of the time,” said Lorenz. “There is also evidence that the frequency of rock movement, which seems to require cold nights to form ice, may have declined since the 1970s due to climate change.”

Sigh. Surely they know better.

Here is the paper from PLOS One: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0105948

Sliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion

Citation: Norris RD, Norris JM, Lorenz RD, Ray J, Jackson B (2014) Sliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion. PLoS ONE 9(8): e105948. doi:10.1371/journal.pone.0105948

Abstract

The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved >60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, “windowpane” ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of ~4–5 m/s. Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2–5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice.

h/t to WUWT reader Joel O’Brien

Advertisements

  Subscribe  
newest oldest most voted
Notify of
Sean Peake

“You’ve got to remember that these are just simple farmers. These are people of the land. The common clay of the new West. You know… morons.”

inMAGICn

“And a laurel and hardy handshake goes to….Sean”

Greg

Mel Brooks, Blazing Saddles

inMAGICn

Hmm. Nasty ol’ global warming again. Odd thing is, it can rain heavily in the Death Valley area. The Racetrack is not in Death Valley, per se. It is to the north and is over 3500′ up. From personal experience over decades (1968 to 2013 off and on), it can get very chilly in the hills around those parts.

mjc

The researchers also observed rock-less trails formed by grounding ice panels – features that the Park Service had previously suspected were the result of tourists stealing rocks.
So is the NPS going to appologize to everyone it’s accused of collecting the rocks?

I believe the term used was “tourists stealing rocks”.

If it’s any consolation, NBC made no mention of global warming in their article, http://www.nbcnews.com/science/weird-science/last-scientists-unravel-mystery-death-valleys-moving-rocks-n190441
Nor did their source, http://www.livescience.com/47585-death-valley-moving-rocks.html which has a nav bar item “global warming”.

eyesonu

This is both interesting and amazing.

Mike Bromley the Kurd

How to turn a fascinating discovery into a platform for proselytizing. That’s just cheap crap. Makes their science seem completely accidental and worthless.

Jimbo

How else would the Scripps Institution of Oceanography have got the funding? If you want money fast you must mention ‘climate change’.

Greg

Good point Jimbo

Leo Morgan

I’m disappointed. In his own article on the subject, Dr. Roy Spencer foretold the ‘blame Climate Change for changes in the rock movement’ meme would arise.Presumably, he missed that those words were in the article itself.
Still, it could be worse. If the rock’s movement increased, we’d be subject to prophecies from the faithful of all our homes going for Death-Valley style ‘walks’.

Richard G

They had this in my local paper and the article there made no mention of climate change. I’m assuming the article Dr. Roy Spencer read also did not contain it. It looks like they got the idea from the good doctor and are now including it.

Jeff

They had a translation of the article over here in Germany, complete with the CAGW meme. Scripps is the academic (? gotta wonder sometimes) answer to journalism’s
“if it bleeds, it leads”. They’re way out left on the left coast of the US…..sad, they used to do really good work, and I think they’re associated with USC, who at least were a conservative University…sigh…

If they had found that in recent years the rocks had been moved further and more frequently, they would have blamed that on … climate change, of course.

durango12

Actually there is a “good reason.” Blaming AGW helps get the next grant. I kid you not. Everyone wants to cash in on the big ATM that is the government (taxpayer) funding machine.

TobiasN

If they get another grant, wow. “look, these meaningless rocks may be sliding on ice less”.

mark l

Amateurs (not a negative connotation) looking to get their findings published and were told to enter the magic words.

i read about this in scientific american or similar 30+ years ago. it was understood at the time that it was caused by ice. it is now recycled as global warming.

George A

Years ago I thought I saw a video, shot at night, of floating ice pushing these rocks around. Not a new discovery.

Eamon Butler

Likewise George. I can’t remember what TV programme it cropped up on, but it was a few years ago.

So, would it be ‘global warming’ that moves rocks on Mars too? http://www.bubblews.com/news/664784-strange-stone-moving-in-mars

Climate change is the catch-all excuse for anything deemed inexplicable, or negative, in any way! What ever happens to be bothering you, guaranteed, climate change caused it….97% of morons said so.

Anyone check to see if they gathered any moss?

Climate Heretic

A rolling stone gathers no moss, so no the stones did not gather any moss!
Regards
Climate Heretic

Bruce Cobb

They don’t get no satisfaction neither.

You may be correct wrt rolling stones but, what about sliding stones?

Aphan

My poppa was a rolling stone…wherever he laid his hat was his home…:)

Alberta Slim

Rolling stones gather no moss. These are sliding stones, and they cannot be harmed by GPS units, or it’s off to jail. …. ;^D

Eamon Butler

They might be linking stones and Greenhouses with this one.

GlynnMhor

Well, they need their funding, so like “Carthago delenda es”, they have to slip in some mention of climate change.

Chris4692

“There is also evidence that the frequency of rock movement, which seems to require cold nights to form ice, may have declined since the 1970s due to climate change.”
Neither more nor less than a plea for funding. Part of making a living from science.

rakman

Back in the day of “nuclear winter”, papers that used that phrase were accepted for publication where those that didn’t have the “phrase that pays” were not published. I believe one enterprising scientist tested the theory by creating a particularly bogus screed, but included the “phrase that pays” and got the paper published.

Peter Miller

And there you have it, “the phrase that pays” and why climate science research has now become so corrupted.

douptingdave

From the scrpps institution of oceanography website Mmmm i wonder if this charming lady had anything to do with nudging these stones in the consensus direction. Naomi Oreskes adjunct professor of geo sciences at Scripps institution of oceanography

Bill Illis

I imagine everyone who works at Scripps Institution of Oceanography or at the home university of University of California, San Diego, knows they have to mention climate change in everything they do or Ms. Oreskes will be coming after your job.

kim

Well, climate change causes many things. Yes it does, furreal.
The problem is the assumption in the writer and the readers that this is ‘man-made climate change’. This erroneous meme is a metastasized cancer.
The only cure for this mass delusion is common cold. Sorry ’bout dat.
================

Travis Casey

Well played.

dp

Is there any profoundly ignorant thing they’re not willing to say?

Yup, ice and rain in Death Valley, definitely Global Warming.

latecommer2014

It also snows inDeath Valley. In 1988 I helped to make a snowman at Scotty’s Castle…global cooling?

Sure, that’s what it was this time, with rocks under observation. But when no one else is looking and some kids from Caltech make a road trip with a few buckets of water and a flask of liquid nitrogen…

Maybe they can do “crop circles” too !!

Leon Brozyna

They were doing so good, solving a decade’s old science mystery … and then they had to go and invoke that old-time AGW religion.

Steve Oregon

AGW rocks!

Jeff

Yeah, Scripps takes it for granite….

“The National Park Service would not let them use native rocks…”
Did the National Park Service personnel and / or leadership believe the rocks were magical?

PiperPaul

I do believe you should use the correct terminology: ‘First Rocks’ or ‘Aboriginal Rocks’.

Jeff

Is there a football team named after them somewhere?
(Probably would be a rather slow one….).

James the Elder

The Toronto Rock pro lacrosse.

jorgekafkazar

I still think the study should be replicated with garden gnomes.

Steve Oregon

They should park Cook, Appell and Nuccitelli out there and track their movement.
Something tells me the rock would out pace them.

DavidS

Interestingly I saw this first on the BBC website and they didn’t mention climate change as part of the report. It’s not like the BBC to miss that sort of opportunity!

Steven

The title is a bit disingenuous. The title suggests that climate change is involved in the phenomenon of the moving rocks where as the quote you highlighted is talking about the frequency of such events decreasing possibly due to climate change. A better headline would have been something like “Sailing stone mystery solved however scientists say for no good reason that climate change could stop the rocks in their tracks”.
In order to avoid people misinterpreting your motives, headlines that accurately reflect the content of the post would be a good policy.

Village Idiot

Hmm…you actually read the article. Watts obviously didn’t, and appears to hope others won’t bother either.
What you’ve revealed is the ‘wind up’ (as in old clockwork children’s toys). It’s a rhetorical device often used here, setting the desired tone for the thread. It’s meant to wind the Villagers up and set them off down the predetermined path. It’s similar to giving a pack of Dobermans a scent, then setting them loose to hunt the quarry. The ‘wind up’ doesn’t actually have to have any truth in it, it’s trigger words or phrases are that are the key.
As you can see from the comments in this thread, it works admirably.

DirkH

Your frustration is a delight to watch.

I copied the following from the link provided with the story:
‘Funding: This work was supported by National Aeronautics and Space Administration NNX07AL32G and NNX12AI04G (to RDL, BJ); Contributions from Interwoof (JMN, JR) and Scripps Institution of Oceanography (RDN) were self-funded. NASA provided support in the form of salaries for authors (RDL and BJ), but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.’
Well, forgive me for being suspicious of that last sentence stating that “NASA…did not have any additional role in…analysis,…” And, this is the cause for my suspicion, “There is also evidence that the frequency of rock movement,…may have declined since the 1970s due to climate change.”
One thing we do know, however, is that the frequency of moon shots by NASA have indeed declined since the 1970s.

Jeff

Hmmm….NASA…National AERONAUTICS and SPACE Administration….they’re looking at the wrong rocks….I think the USGS (US Geological Survey) or a similar group should be looking at these earth-based rocks….
As was mentioned above, this is recycled “science”….must have been a slow news day (erm, the volcanos worldwide beg to differ, but hey, it’s all in the name of funding…the bay of funding?)

Greg

“There is also evidence that the frequency of rock movement,…may have declined since the 1970s due to climate change.”
“May have” is not evidence, it is lack of evidence.

Greg

PS the paper does not even mention the word climate. This is just Lorentz adding his bit of GW spin in the Scripps article.

Mr Mike

Lorentz’s comment was based on a study he performed last year titled “Declining rock movement at Racetrack Playa, Death Valley National Park: an indicator of climate change?” See manuscript marked “Accepted for publication 24 December 2013 in Geonmorphology” at http://www.lpl.arizona.edu/~rlorenz/climatechange_preprint.pdf. The problem is, the two key determinants of rock movement identified by that paper – thick ice and high wind – are contradicted by the latest study described above, in which thin ice and modest winds were observed moving rocks. I’m sure that’s why his previous study was not cited in the later paper.

Gary in Erko

“the most boring experiment ever”
No. This is – http://smp.uq.edu.au/content/pitch-drop-experiment

I’ll bet global warming is speeding that pitch up.
That is, of course, if it’s a bad thing for the pitch drop to be speeded up.

Greg

9 drops in 83 years but most of the biggest drops have occurred in the last three decades !! 😉

Greg

9 drops in 83 years, that’s about 9y between each drip depending upon the date of the last drip event.
UQ is in Brisbane, one of the most easterly points on Australia’s Pacific coast just below the tropic of Capricorn. It’s climate will be dominated by by surrounding sea temperatures.
Global SST shows a circa 9y oscillation:
http://climategrog.wordpress.com/?attachment_id=981
Pitch drops “may be” linked to climate change !!
Now we just need to see whether the drips have been happening more frequently in “the latter half of the 20th century” and test whether it correlates with human CO2 emissions.

Jim South London

[snip – off topic -mod]

ralfellis

Well, perhaps that is because the Osama administration os desperately trying to convince people that that is so.
Quote:
“The FBI’s most recent national threat assessment for domestic terrorism makes no reference to Islamist terror threats, despite last year’s Boston Marathon bombing and the 2009 Fort Hood shooting.”
http://freebeacon.com/national-security/fbi-national-domestic-threat-assessment-omits-islamist-terrorism
Many people believe the propaganda.
Ralph

Tom in Florida

Intelligence agencies do not reveal what they know and how they know it. Releasing such information would compromise the source and shut off further information. So a failure to mention ISIS could mean that they have a steady source info from inside. It is equally plausible that Obama agrees with the purpose of ISIS and his lack of strategy is his strategy for them to succeed.

DirkH

[snip off topic -mod]

latecommer2014

[snip -off topic -mod]

jaffa68

At 2:15 the ginger bird obviously thinks the Global Warming / ISIS link is nonsense.

ralfellis

.
Regards the moving stones, I did not immediately understand the mechanism here.
The ice is not pushing stones in front of it. As the pics demonstrate, what appears to be happening is that a raft of ice surrounds a stone or a group of stones. As the ice-sheets break up, a light wind can now act upon that entire ice-raft, which may be 50 meters or more across. And so the wind acts upon all the stones within that raft simultaneously, so the stones all make parallel tracks as they move while trapped in the raft.
So the ice-sheet is a force multiplier, providing a considerably increased surface area for the wind to act upon, and thus a considerably increased force upon the stones that are trapped within that thin ice-raft.
Images of all the rocks moving together:
http://i.dailymail.co.uk/i/pix/2014/08/28/1409217577213_wps_16_Death_Valley_rocks1_PNG.jpg
http://i.dailymail.co.uk/i/pix/2014/08/28/1409217582701_wps_17_Death_Valley_rocks1_PNG.jpg
Ralph

Richard G

ralfellis, your explanation of the mechanism makes more sense than what I thought I read in the article.

Ralph,
You answered the question I was going to ask.
Thank you.

Jimbo

ralfellis, thank you. The visuals say a lot.

Ashby Manson

Presumably the water will partially suspend the stones and the fine particulate mud will lower the coefficient of friction allowing the stones to slide while trapped in the ice sheet. It’s actually a pretty nifty solution to a strange phenomena.

Aphan

Incredible photo! Now…if we could just find out if the winds over the Nazca Plains blow in extremely accurate pictorial directions…..

Jeff

Good explanatin – think hydroplaning or driving on ice with bald tires (OK, think but don’t do…ouch…). I think ice skates do something similar (if memory serves me right…).

Alberta Slim

Looks like the best explanation.
Unless it’s aliens ?? Where is Von Daniken when you need him? …;^D

Olaf Koenders

They weren’t allowed to use native rocks, so they had to import their own that were obviously polluted by climate change.

Aphan

Unable to use actual sailing rocks, proxies were brought in by Mann, selected specifically for their propensity to “sail” in observable hockey stick patterns…

Jimbo

Mystery of the sailing stones of Death Valley solved – ‘climate change’ immediately blamed for no good reason

I can’t wait to see this headline.

Mystery global warming solved – man was blamed for no good reason

The add-on about Global Warming is like a genuflection. It is like Galileo bowing to the Pope. His private opinion remains unstated, except in cartoons that have those little balloons floating above people’s heads.
If we survive this period of madness, and our papers are read by our great-grandchildren, they will roll their eyes when they read these genuflections.

jaffa68

OMG
“the frequency of rock movement….may have declined….due to climate change”
We really are in trouble, rocks “may” be moving less, what on earth are we going to do? Think of the children.

mikeishere

“There is also evidence that the frequency of rock movement, … may have declined since the 1970s due to climate change.”
I agree, this is becoming an obligatory phrase in all research papers to assure continued funding. However, using the word “declined” was in itself a very gutsy call. In a post climate-gate world they need to be reminded to avoid any and all linkage between the phrase “climate change” and words such as decline or decrease.
In this case it could have been better written as: “There is also evidence that the durations of rock inactivity, … may have increased since the 1970s due to climate change.”

PiperPaul

“There is also evidence that the frequency of rock movement, which seems to require cold nights to form ice, may have declined since the 1970s due to climate change.”
Ka-ching! Has anyone yet proposed Climate Change Bingo? Or some kind of axiom, like, “The probability of an Earth science-related ‘news’ article referencing climate change increases…

EternalOptimist

If these are climate related rocks they should be homogenized immediately. I suggest teleconnecting them to Stonehenge to make them stand up and grow lintels

Ralph Kramden

ABC News covered this story and they did not mention climate change.

Mr Mike

The actual study published in PLOS One does not mention climate change.

The critical factor is the availability of surface water to freeze on cold nights. An extended drought is the more likely cause of less rock movement. They give no evidence for significantly fewer freezing cold nights when water is available. Death valley would be a good place to test the CO2 greenhouse hypothesis. Water freezes faster there at night because the air is dry (no clouds) and radiates to space. If CO2 concentrations are reducing that rate of radiation, one should be able to detect that effect with the seasonal and year to year changes in CO2 concentrations. The night time rate of freezing of water is a measure of radiation to space on dry, cloudless nights.

Bob Shapiro

I seem to remember reading questions of how the Egyptians were able to move huge stones from the quarries hundreds of miles away to their current sites. Might they have used this effect by watering the selected path for the stone, letting it freeze/remelt, and then pushing the stone?

Don Easterbrook

The mysterious sliding rocks of Death Valley have been known for 65 years. Here is what I wrote about them in “Surface Processes and Landforms,” 1999 (p.476-478) with photos and tracks of sliding stones.
“The Mysterious Sliding Rocks of Death Valley National Monument”
“For many years, geomorphologists have been intrigued by the mystery of the sliding boulders of Racetrack Playa in Death Valley National Monument (Figure 17—5). The mud- cracked surface of the playa is criss-crossed by shallow troughs trailing behind rocks (Figure 17—6) ranging from pebbles to boulders weighing more than 700 pounds. The playa surface is nearly flat, so the rocks are clearly not sliding downhill. At first, speculation of the cause of the sliding rocks centered around the possibility that the rocks had been pushed across the surface by humans, but the remoteness of the area argued against such an explanation. Few people brave the unpaved, 30-mile road that leads to Race- track playa. Tracks of sliding rocks have been reported on at least eight other playas in California and Nevada and in the Middle East. The sliding-rock trails vary both in length and direction. Some trails make straight, roughly parallel lines for several hundred meters (Figures 17—6A and 17—7B). Others curve gradually, criss-cross one another (Figure 17—6B) or change direction abruptly (Figures 17—6C and 17—7B). After traveling hundreds of meters along straight or gently curving paths, many trails end with a scribbled path (Figure 17—7B). The greatest concentration of sliding rocks occurs in the south- eastern portion of Racetrack playa where 28 sliding boulders have been counted in a one-half square mile (1.3 km2) area (Messina, 1997).
The first scientific papers describing the sliding rocks appeared in 1948 (McAllister and Agnew, 1948), followed by several in the following decades (Shelton, 1953; Stanley, 1 Schumm, 1956, Sharp, 1960; Sharp and Carey, 1976). All suggested that high winds, preceded by wetting of the playa had pushed the rocks across the slippery surface. However, despite four decades of investigation of the sliding rock scientists and park rangers, no one has ever seen one move.
Ice is known to occasionally form as thick as 10 centimeters on Racetrack playa, and some researchers have suggested that as wind pushes ice rafts, rocks in the ice are drag across the playa surface, leaving parallel trails. Stanley (1955) first suggested that ice floating in a shallow lake on the playa might be involved in moving the stones, based largely on parallel paths taken by the rocks. However, Sharp and C (1976) placed two small rocks within a circle of steel rods later found that one of them had escaped. They noted moving ice could not have accomplished this and, along their observation that tracks did not maintain constant separation, concluded that ice was not necessary to move the rocks. The ice-rafting hypothesis was recently revived by Reid et al. (1995) on the basis of mapping of similar, parallel paths of rocks sliding on the Racetrack Playa. They suggest rocks of different mass should not be propelled equally high winds without ice and that the wetted playa surface not as slippery as once thought. They explained the observed lack of parallel paths between some tracks as having been caused by breaking up of the ice into smaller individual blocks and concluded that ice was necessary for playa rocks to slide.
FIGURE 17—6 (A.) Two sliding rocks leaving trails on Racetrack pla Death Valley National Monument, California. (Photo Messina) (B.) Trails of sliding rocks crossing one another, Racetrack playa, Death Valley National Monument, California. by P. Messina) (C.) Abrupt change in direction of sliding rock trail, Racetrack playa, Death Valley National Monument, California. (Photo by P. Messina)
In a discussion of the conclusions of Reid et al., Sharp (1996) presented evidence that at least some of the rocks must have slid without the presence of ice. Messina (1997) monitored many sliding rocks on Racetrack playa with GPS (ground positioning system) and found that, although many of the trails were ap- proximately parallel (Figure 17—7), in detail they converged and diverged and in some cases appeared to be random, a situation inconsistent with movement of stones frozen in a sheet of ice.”
What is new about this study is the first observation of stones moving under known conditions. As such, it is an important contribution.

Gary Pearse

Forgive me, but the explanation by the good doctors of an earlier theory that the rocks were blown by big winds makes me hope no one was paid for that idea!!! One look at the photos of the dirt ridges on either side of the trails of the rocks would tell you that it wasn’t big winds on a dry plain. These would have been erased by the very winds in play. A good foundation engineer with samples of the side ‘moraines’ would be able to tell you if they were formed in saturated clay (some binding salt, caleche?…) or dry clay. Probably a cursory look would be enough. Several other things:
a) a calculation of the wind force per square foot push surface would tell you what kind of a wind you would need. Some one reading this could do this calc. in a few minutes.
b) the precise straight line directions for long stretches tells you they had to have made the move under a particularly exact wind direction or there would be many shallow zigs and zags depending on the variability of directions of wind events. These straight line stretches would be highly likely from one windy event – not a number of them spaced by years.
c) Bouyancy would help the process if water flooding was a factor.

Gary Pearse

Another thing I would have done is a level survey of the playa. Does it not have a very slight down slope from the margins in toward the middle? Simple observation is very valuable but an engineer would have gathered a lot of data beforehand.

The reason these cousins were able to observe this horizontal rock slide is because Climate Change has made these events more rare.
(They are less rare would be the obvious inference. But what do I know?)

more soylent green!

Since the climate always changes and climate change is the natural state of affairs, why not? But when you have to account for the fact this phenomenon was first documented in 1915, it’s kinda hard to tie it all together.
This is only an issue if facts are a concern.

kim

So it’s the reporter who added the ‘climate change’ bit? He’s due for a conversation with the editor.
Oops, that’s probably the one who made him put it in.
===================

Svend Ferdinandsen

I can only say that now we will miss all the good stories that the scientist invented instead of observing.