[meteorite-list] Big Splash Theory Says Meteors Hit Regularly

From: Stefan Brandes <brandes_at_meteoritecentral.com>
Date: Tue Nov 14 14:03:35 2006
Message-ID: <000601c7081f$92323200$f49a2fd5_at_FORCEMACHINE>

Nice idea finding craters by just looking where the chevrons point to :)

Does anybody know the crater just left to the south of Chile ?

http://graphics8.nytimes.com/images/2006/11/13/science/1114WAVE_Lg.jpg


Stefan


----- Original Message -----
From: "Ron Baalke" <baalke_at_zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list_at_meteoritecentral.com>
Sent: Tuesday, November 14, 2006 6:25 PM
Subject: [meteorite-list] Big Splash Theory Says Meteors Hit Regularly


>
> http://www.nytimes.com/2006/11/14/science/14WAVE.html
>
> Ancient Crash, Epic Wave
> By SANDRA BLAKESLEE
> New York Times
> November 14, 2006
>
> At the southern end of Madagascar lie four enormous wedge-shaped
> sediment deposits, called chevrons, that are composed of material from
> the ocean floor. Each covers twice the area of Manhattan with sediment
> as deep as the Chrysler Building is high.
>
> On close inspection, the chevron deposits contain deep ocean
> microfossils that are fused with a medley of metals typically formed by
> cosmic impacts. And all of them point in the same direction - toward the
> middle of the Indian Ocean where a newly discovered crater, 18 miles in
> diameter, lies 12,500 feet below the surface.
>
> The explanation is obvious to some scientists. A large asteroid or
> comet, the kind that could kill a quarter of the world's population,
> smashed into the Indian Ocean 4,800 years ago, producing a tsunami at
> least 600 feet high, about 13 times as big as the one that inundated
> Indonesia nearly two years ago. The wave carried the huge deposits of
> sediment to land.
>
> Most astronomers doubt that any large comets or asteroids have crashed
> into the Earth in the last 10,000 years. But the self-described "band of
> misfits" that make up the two-year-old Holocene Impact Working Group say
> that astronomers simply have not known how or where to look for evidence
> of such impacts along the world's shorelines and in the deep ocean.
>
> Scientists in the working group say the evidence for such impacts during
> the last 10,000 years, known as the Holocene epoch, is strong enough to
> overturn current estimates of how often the Earth suffers a violent
> impact on the order of a 10-megaton explosion. Instead of once in
> 500,000 to one million years, as astronomers now calculate, catastrophic
> impacts could happen every few thousand years.
>
> The researchers, who formed the working group after finding one another
> through an international conference, are based in the United States,
> Australia, Russia, France and Ireland. They are established experts in
> geology, geophysics, geomorphology, tsunamis, tree rings, soil science
> and archaeology, including the structural analysis of myth. Their
> efforts are just getting under way, but they will present some of their
> work at the American Geophysical Union meeting in December in San
> Francisco.
>
> This year the group started using Google Earth, a free source of
> satellite images, to search around the globe for chevrons, which they
> interpret as evidence of past giant tsunamis. Scores of such sites have
> turned up in Australia, Africa, Europe and the United States, including
> the Hudson River Valley and Long Island.
>
> When the chevrons all point in the same direction to open water, Dallas
> Abbott, an adjunct research scientist at Lamont-Doherty Earth
> Observatory in Palisades, N.Y., uses a different satellite technology to
> look for oceanic craters. With increasing frequency, she finds them,
> including an especially large one dating back 4,800 years.
>
> So far, astronomers are skeptical but are willing to look at the
> evidence, said David Morrison, a leading authority on asteroids and
> comets at the NASA Ames Research Center in Mountain View, Calif. Surveys
> show that as many as 185 large asteroids or comets hit the Earth in the
> far distant past, although most of the craters are on land. No one has
> spent much time looking for craters in the deep ocean, Dr. Morrison said,
> assuming young ones don't exist and that old ones would be filled with
> sediment.
>
> Astronomers monitor every small space object with an orbit close to the
> Earth. "We know what's out there, when they return, how close they
> come," Dr. Morrison said. Given their observations, "there is no reason
> to think we have had major hits in the last 10,000 years," he continued,
> adding, "But if Dallas is right and they find 10 such events, we'll have
> a real contradiction on our hands."
>
> Peter Bobrowski, a senior research scientist in natural hazards at the
> Geological Survey of Canada, said "chevrons are fantastic features" but
> do not prove that megatsunamis are real. There are other interpretations
> for how chevrons are formed, including erosion and glaciation. Dr.
> Bobrowski said. It is up to the working group to prove its claims, he
> said.
>
> William Ryan, a marine geologist at the Lamont Observatory, compared Dr.
> Abbott's work to that of other pioneering scientists who had to change
> the way their colleagues thought about a subject.
>
> "Many of us think Dallas is really onto something," Dr. Ryan said. "She
> is building a story just like Walter Alvarez did." Dr. Alvarez, a
> professor of earth and planetary sciences at the University of
> California Berkeley, spent a decade convincing skeptics that a giant
> asteroid wiped out the dinosaurs 65 million years ago.
>
> Ted Bryant, a geomorphologist at the University of Wollongong in New
> South Wales, Australia, was the first person to recognize the palm
> prints of mega-tsunamis. Large tsunamis of 30 feet or more are caused by
> volcanoes, earthquakes and submarine landslides, he said, and their
> deposits have different features.
>
> Deposits from mega-tsunamis contain unusual rocks with marine oyster
> shells, which cannot be explained by wind erosion, storm waves,
> volcanoes or other natural processes, Dr. Bryant said.
>
> "We're not talking about any tsunami you're ever seen," Dr. Bryant said.
> "Aceh was a dimple. No tsunami in the modern world could have made these
> features. End-of-the-world movies do not capture the size of these
> waves. Submarine landslides can cause major tsunamis, but they are
> localized. These are deposited along whole coastlines."
>
> For example, Dr. Bryant identified two chevrons found over four miles
> inland near Carpentaria in north central Australia. Both point north.
> When Dr. Abbott visited a year ago, he asked her to find the craters.
>
> To locate craters, Dr. Abbott uses sea surface altimetry data.
> Satellites scan the ocean surface and log the exact height of it.
> Underwater mountain ranges, trenches and holes in the ground disturb the
> Earth's gravitational field, causing sea surface heights to vary by
> fractions of an inch. Within 24 hours of searching the shallow water
> north of the two chevrons, Dr. Abbott found two craters.
>
> Not all depressions in the ocean are impact craters, Dr. Abbott said.
> They can be sink holes, faults or remnant volcanoes. A check is needed.
> So she obtained samples from deep sea sediment cores taken in the area
> by the Australian Geological Survey.
>
> The cores contain melted rocks and magnetic spheres with fractures and
> textures characteristic of a cosmic impact. "The rock was pulverized,
> like it was hit with a hammer," Dr. Abbott said. 'We found diatoms fused
> to tektites," a glassy substance formed by meteors. The molten glass and
> shattered rocks could not be produced by anything other than an impact,
> she said.
>
> "We think these two craters are 1,200 years old," Dr. Abbott said. The
> chevrons are well preserved and date to about the same time.
>
> Dr. Abbott and her colleagues have located chevrons in the Caribbean,
> Scotland, Vietnam and North Korea, and several in the North Sea.
>
> Heather Hill State Park on Long Island has a chevron whose front edge
> points to a crater in Long Island Sound, Dr. Abbott said. There is
> another, very faint chevron in Connecticut, and it points in a different
> direction.
>
> Marie-Agn?s Courty, a soil scientist at the European Center for
> Prehistoric Research in Tautavel, France, is studying the worldwide
> distribution of cosmogenic particles from what she suspects was a major
> impact 4,800 years ago.
>
> But Madagascar provides the smoking gun for geologically recent impacts.
> In August, Dr. Abbott, Dr. Bryant and Slava Gusiakov, from the
> Novosibirsk Tsunami Laboratory in Russia, visited the four huge
> chevrons to scoop up samples.
>
> Last month, Dee Breger, director of microscopy at Drexel University in
> Philadelphia, looked at the samples under a scanning electron microscope
> and found benthic foraminifera, tiny fossils from the ocean floor,
> sprinkled throughout. Her close-ups revealed splashes of iron, nickel
> and chrome fused to the fossils.
>
> When a chondritic meteor, the most common kind, vaporizes upon impact in
> the ocean, those three metals are formed in the same relative
> proportions as seen in the microfossils, Dr. Abbott said.
>
> Ms. Breger said the microfossils appear to have melded with the
> condensing metals as both were lofted up out of the sea and carried long
> distances.
>
> About 900 miles southeast from the Madagascar chevrons, in deep ocean,
> is Burckle crater, which Dr. Abbott discovered last year. Although its
> sediments have not been directly sampled, cores from the area contain
> high levels of nickel and magnetic components associated with impact
> ejecta.
>
> Burckle crater has not been dated, but Dr. Abbott estimates that it is
> 4,500 to 5,000 years old.
>
> It would be a great help to the cause if the National Science Foundation
> sent a ship equipped with modern acoustic equipment to take a closer
> look at Burckle, Dr. Ryan said. "If it had clear impact features, the
> nonbelievers would believe," he said.
>
> But they might have more trouble believing one of the scientists, Bruce
> Masse, an environmental archaeologist at the Los Alamos National
> Laboratory in New Mexico. He thinks he can say precisely when the comet
> fell: on the morning of May 10, 2807 B.C.
>
> Dr. Masse analyzed 175 flood myths from around the world, and tried to
> relate them to known and accurately dated natural events like solar
> eclipses and volcanic eruptions. Among other evidence, he said, 14 flood
> myths specifically mention a full solar eclipse, which could have been
> the one that occurred in May 2807 B.C.
>
> Half the myths talk of a torrential downpour, Dr. Masse said. A third
> talk of a tsunami. Worldwide they describe hurricane force winds and
> darkness during the storm. All of these could come from a mega-tsunami.
>
> Of course, extraordinary claims require extraordinary proof, Dr. Masse
> said, "and we're not there yet."
>
> -----------------------------------------------------------------------
>
> http://www.smh.com.au/news/world/big-splash-theory-says-meteors-hit-regularly/2006/11/14/1163266554476.html
>
> Big splash theory says meteors hit regularly
> Sandra Blakeslee
> New York Times
> November 15, 2006
>
> A LARGE asteroid or comet, the kind that could kill a quarter of the
> world's population, smashed into the Indian Ocean 4800 years ago,
> producing a tsunami more than 180 metres high - about 13 times as big as
> the one that hit Indonesia almost two years ago.
>
> The startling claim is made by a group of researchers, including
> Australians, who cite as evidence a newly discovered crater, 29
> kilometres in diameter, 3800 metres below the surface of 1600 kilometres
> south-east of Madagascar.
>
> Most astronomers doubt that any large comets or asteroids have crashed
> into the Earth in the past 10,000 years. But the self-described "band of
> misfits" that make up the Holocene Impact Working Group say astronomers
> simply have not known how or where to look for evidence of such impacts
> along the world's shorelines and in the deep ocean.
>
> Scientists in the working group say the evidence for such impacts during
> the past 10,000 years is strong enough to overturn estimates of how
> often the Earth suffers a violent impact on the order of a 10-megaton
> explosion. Instead of once in 500,000 to 1 million years, as astronomers
> now calculate, catastrophic impacts could happen every few thousand years.
>
> The researchers, who formed the working group after finding one another
> through an international conference, are based in the US, Australia,
> Russia, France and Ireland. This year the group started using Google
> Earth, a free source of satellite images, to search the globe for
> chevrons - enormous wedge-shaped sediment deposits, that are composed of
> material from the ocean floor - which they interpret as evidence of past
> giant tsunamis.
>
> Ted Bryant, a geomorphologist at the University of Wollongong, was the
> first person to recognise the palm prints of mega-tsunamis. Large
> tsunamis of 10 metres or more were caused by volcanoes, earthquakes and
> submarine landslides, Dr Bryant said, and their deposits have different
> features.
>
> Deposits from mega-tsunamis contained unusual rocks with marine oyster
> shells, which could not be explained by wind erosion, storm waves,
> volcanoes or other natural processes, he said.
>
> "We're not talking about any tsunami you've ever seen. Aceh was a
> dimple. No tsunami in the modern world could have made these features."
> Dr Bryant identified two chevrons found about six kilometres inland from
> the Gulf of Carpentaria. Both point north.
>
> When Dallas Abbott, an adjunct research scientist at Lamont-Doherty
> Earth Observatory, in New York, visited a year ago, he asked her to find
> the craters.
>
> To locate craters Dr Abbott uses sea surface altimetry data. Satellites
> scan the ocean surface and log the exact height of it. Underwater
> mountain ranges, trenches and holes in the ground disturb the Earth's
> gravitational field, causing sea surface heights to vary by fractions of
> a centimetre. Within 24 hours of searching the shallow water north of
> the two chevrons she found two craters.
>
> She obtained samples from deep sea sediment cores taken in the area by
> the Australian Geological Survey.
>
> "We think these two craters are 1200 years old," she said. The chevrons
> are well preserved and date to about the same time.
> ______________________________________________
> Meteorite-list mailing list
> Meteorite-list_at_meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
Received on Tue 14 Nov 2006 02:03:28 PM PST