[meteorite-list] Why Are Death Valley's Rocks Moving Themselves? --not off-topic at all!

From: Ed Deckert <edeckert_at_meteoritecentral.com>
Date: Sat, 19 Feb 2011 23:38:47 -0500
Message-ID: <CF2EEF1F39934285B7959F40FDE84AAA_at_MAINPC>

Ah, so rocks are truly migratory then!

Ed

----- Original Message -----
From: "Michael Gilmer" <meteoritemike at gmail.com>
To: "Stuart McDaniel" <actionshooting at carolina.rr.com>
Cc: "Michael Groetz" <mpg4444 at gmail.com>; "Meteorite List"
<meteorite-list at meteoritecentral.com>; "Rob Matson"
<mojave_meteorites at cox.net>
Sent: Saturday, February 19, 2011 11:28 PM
Subject: Re: [meteorite-list] Why Are Death Valley's Rocks Moving
Themselves? --not off-topic at all!


> "ice rafting" is a misleading term, it actually has nothing to do with
> ice. The term is used to describe what happens when the martian blood
> vessels inside the rock come to life and begin the process of
> animating the stone so it can move. ;)
>
> ----------------------------------------------------------------------
> Mike Gilmer - Galactic Stone & Ironworks Meteorites
>
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> -----------------------------------------------------------------------
>
> On 2/19/11, Stuart McDaniel <actionshooting at carolina.rr.com> wrote:
>> Would you please explain what is meant by "ice-rafting" in laymen's
>> terms??
>>
>>
>>
>> Stuart McDaniel
>> Lawndale, NC
>> Secr.,
>> Cleve. Co. Astronomical Society
>> -----Original Message-----
>> From: Rob Matson
>> Sent: Saturday, February 19, 2011 3:06 PM
>> To: Michael Groetz ; Meteorite List
>> Subject: [meteorite-list] Why Are Death Valley's Rocks Moving
>> Themselves? --not off-topic at all!
>>
>> Hi Michael,
>>
>> IMHO, it's definitely ice-rafting. It happens on any desert playa that
>> is hard enough, receives sufficient winter rains, and gets cold enough
>> to freeze at night. In California, I've seen the rock furrows at Silver
>> Dry Lake, Superior Dry Lake, Cuddeback Dry Lake and (most recently)
>> Coyote Dry Lake. I've also seen them on some Nevada playas as well
>> as the Alvord Desert in Oregon, and they occur in Arizona, as well.
>>
>> SoCal got a lot of rain this past December -- so much so that even
>> after three weeks of dry weather in January the northern third of
>> Coyote was under water. I've never seen this in the decade I've been
>> going there, and sure enough I saw rock trails there for the first
>> time last month.
>>
>> Bob Verish, Nick Gessler and I coauthored an abstract and presentation
>> on this subject, and in particular its implications for meteorite
>> recovery, at the 65th Annual Meeting of the Meteoritical Society
>> in 2002:
>>
>> http://adsabs.harvard.edu/full/2002M%26PSA..37Q..51G
>>
>> Cheers,
>> Rob
>>
>>
>> -----Original Message-----
>> From: meteorite-list-bounces at meteoritecentral.com
>> [mailto:meteorite-list-bounces at meteoritecentral.com]On Behalf Of Michael
>> Groetz
>> Sent: Friday, February 18, 2011 5:24 PM
>> To: Meteorite List
>> Subject: [meteorite-list] OT (Sorta...) Why Are Death Valley's Rocks
>> MovingThemselves?
>>
>>
>> Interesting photo- wish I could crawl out of my chair in Ohio and
>> go check those rocks out.
>> I know this has been discussed on the list before.
>> Have a good night.
>> Mike
>>
>> http://www.foxnews.com/scitech/2011/02/18/death-valleys-rocks-moving-racetra
>> ck-playa/
>>
>> Why Are Death Valley's Rocks Moving Themselves?
>>
>> By Philip Schewe
>>
>> Published February 18, 2011 | Inside Science News Service
>>
>> Death Valley National Park contains many mysteries, including one of
>> nature's strangest phenomena: rocks that seem to move around all on
>> their own.
>>
>> In the remote, almost totally dry lakebed called Racetrack Playa, some
>> of the rocks move themselves across the desert floor when people
>> aren't watching.
>>
>> Scientists know the rocks move because they leave narrow tracks
>> trailing behind them, but they haven't actually seen it happen. And
>> although one can't entirely rule out the possibility of some prank
>> being played, at least some of the rocks appear to be moving under
>> natural circumstances.
>>
>> It doesn't rain often in Racetrack Playa, and when it does the lakebed
>> can flood. The rocks don't float exactly, but the main explanation for
>> their movement is that moisture can make the mud on which the rocks
>> sit more slick, making it easier for high winds to push the rocks
>> along. Another explanation offered is that the temporary deposit of
>> water, chilled to form extensive sheets of ice, might help to reflect
>> and focus the winds, making it easier for the rocks to move.
>>
>> The winds required to move rocks in this way would seem to be at the
>> level of 100 mph or more. That's why the rocks are sometimes referred
>> to as "sailing stones." They are rare but they have been noticed in
>> Racetrack Playa and a few other arid places around the world subject
>> to occasional floods
>>
>> Ralph Lorenz, a scientist at Johns Hopkins University, offers a new
>> explanation. The rocks are actually lifted up by the ice, or at least
>> made more buoyant by the ice, making it easier for the rocks to
>> migrate. If the rocks are moving about on ice rafts, the ground below
>> cannot offer as much resistance against their motion and the winds
>> needed for movement wouldn't have to be as great, he argued.
>>
>> So why hasn't the motion been observed?
>>
>> "Movement happens for only tens of seconds, at intervals spaced
>> typically by several years," said Lorenz. "This would demand
>> exceptional patience as well as luck."
>>
>> So, the rocks are probably traveling on the coldest and windiest days
>> that occur over a period of several years. The most likely time would
>> be in the very early dawn. Little wonder no one is around to witness
>> the event.
>>
>> Lorenz and his colleagues would like to install inexpensive time-lapse
>> monitoring of the Playa area, using digital cameras. The lakebed is
>> about 2.5 miles long and 1.25 miles wide. They have also performed
>> some laboratory tests by blowing on ice-assisted rocks. These simple
>> tests support the ice-raft hypothesis. The results appear in the
>> January 2011 issue of the American Journal of Physics.
>>
>> An additional reason for studying the rocks of Racetrack Playa is that
>> its qualities resemble those at a drying-up lake on Saturn's moon
>> Titan. Pictures taken by the Cassini-Huygens mission reveal what look
>> like river channels, cobblestones, and lake beds or mud flats. Only at
>> Titan's "Ontario Lacus," as one interesting site is called, the runoff
>> consists of liquid hydrocarbons, not water. Some pictures even seem to
>> be showing a "bathtub ring" left by what is probably a drying lake.
>>
>> One of Lorenz's colleagues, Brian K. Jackson, who works at NASA's
>> Goddard Space Flight Center, also likes the idea that their research
>> at Racetrack Playa has a dual purpose.
>>
>> "It's been exciting trying to solve a mystery that has resisted
>> solution for sixty years," Jackson said. "Scientific accounts of the
>> Racetrack Playa rocks go back to at least 1948, and there were
>> certainly stories about the playa long before that.
>>
>> And Jackson also believes discoveries in Death Valley, here on Earth,
>> will help us to better understand similar real estate on Titan or
>> Mars.
>>
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Received on Sat 19 Feb 2011 11:38:47 PM PST