Free Republic
Browse · Search
General/Chat
Topics · Post Article

Skip to comments.

North America comet theory questioned
Nature ^ | 12 Oct 2009 | Rex Dalton

Posted on 10/13/2009 8:08:29 AM PDT by BGHater

No evidence of an extraterrestrial impact 13,000 years ago, studies say.

An independent study has cast more doubt on a controversial theory that a comet exploded over icy North America nearly 13,000 years ago, wiping out the Clovis people and many of the continent's large animals.

Sediments at the San Jon site, in eastern New Mexico, contained very low abundances of magnetic spherules said to be evidence of an impact.Vance Holliday

Archaeologists have examined sediments at seven Clovis-age sites across the United States, and did not find enough magnetic cosmic debris to confirm that an extraterrestrial impact happened at that time, says the report in the Proceedings of the National Academy of Sciences (PNAS)1. It is the latest of several studies unable to support aspects of the impact hypothesis.

In 2007, a team led by Californian researchers announced a theory2 that a comet or asteroid had exploded over the North American ice sheet, creating widespread fire and an atmospheric soot burst followed by a cooling period known as the Younger Dryas. Sometime after this, the Clovis people, sophisticated large-animal hunters known for their spear points, mysteriously disappeared; the team linked their vanishing to the environmental effects of the proposed impact.

Key evidence came in the form of magnetic microspherules discovered in sediments at 25 locations, including eight Clovis-age sites. Richard Firestone, of Lawrence Berkeley National Laboratory in California, and his colleagues argued that the microspherules were remnants of cosmic debris from an explosion.

But in more than 18 months of sedimentary analysis, a team led by Todd Surovell, an archaeologist at the University of Wyoming in Laramie, was unable to detect microspherule peaks. Two of the seven sites the group studied were places where Firestone's team identified spherule peaks.

"I spent hundreds of hours at the microscope examining sediment samples," says Surovell, "and I didn't find any physical evidence to support their theory."

Standing firm

The other team isn't backing down. "Their study doesn't negate our hypothesis," says James Kennett, a palaeoceanographer at the University of California at Santa Barbara and one of Firestone's co-authors. Another co-author, avocational geophysicist Allen West of Prescott, Arizona, says that Surovell's group didn't use the correct technique to extract, identify and quantify the microspherules.

Several other groups have been unable to support important aspects of the comet theory.

In a PNAS article published in February3, Jennifer Marlon, a doctoral geography student at the University of Oregon in Eugene, and her colleagues found no systematic burning of biomass — as would have occurred if continent-wide fires had happened — at the time of the Younger Dryas in pollen and charcoal records at 35 sites. And at the Ecological Society of America meeting in Albuquerque, New Mexico, in August, Jacquelyn Gill, a palaeoecology doctoral student at the University of Wisconsin-Madison, reported finding no evidence of massive burning in sediment cores taken from lake beds in Ohio and Indiana.

Kennett, however, calls these studies "flawed". In August, his team published a report4 saying they had found nanometre-sized diamonds, purportedly created during an impact, and soot in sediments dated to the Younger Dryas on Santa Rosa Island, off the coast of California.

More studies of the theory — both critical and supportive — are in the publishing pipelines at other journals.

Surovell's co-author Vance Holliday, an archaeologist at the University of Arizona in Tucson, and his colleagues have an article in press at Current Anthropology that says the archaeological and geochronological records don't support a collapse of Clovis people at the time of the purported impact.


TOPICS: Astronomy; History; Science
KEYWORDS: catastrophism; clovis; comet; godsgravesglyphs; science

1 posted on 10/13/2009 8:08:29 AM PDT by BGHater
[ Post Reply | Private Reply | View Replies]

To: SunkenCiv

-shrug-


2 posted on 10/13/2009 8:08:54 AM PDT by BGHater ("real price of every thing ... is the toil and trouble of acquiring it")
[ Post Reply | Private Reply | To 1 | View Replies]

To: BGHater

Dueling theories.


3 posted on 10/13/2009 8:10:07 AM PDT by cripplecreek (Seniors, the new shovel ready project under socialized medicine.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: BGHater
It is so difficult to understand clearly what happened sometimes a hundred years ago let alone thousands of years ago. I don't think that the Clovis people disappeared but got absorbed into some of the newer tribes which got absorbed again by even newer tribes. It is hard to determine the difference between genetic traces of early fur traders in studies and stone age Frenchmen. As to the large fauna disappearing, well people get hungry and something extra large sized could feed a whole village for awhile. Combine that with environmental stresses and things disappear. I don't think that a single spectacular event can be blamed for the changes that occurred.
4 posted on 10/13/2009 8:22:35 AM PDT by dog breath
[ Post Reply | Private Reply | To 1 | View Replies]


The Cycle of Cosmic Catastrophes: Flood, Fire, and Famine in the History of Civilization The Cycle of Cosmic Catastrophes:
Flood, Fire, and Famine
in the History of Civilization

by Richard Firestone,
Allen West, and
Simon Warwick-Smith


5 posted on 10/13/2009 5:36:57 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/__Since Jan 3, 2004__Profile updated Monday, January 12, 2009)
[ Post Reply | Private Reply | To 1 | View Replies]

To: 75thOVI; aimhigh; Alice in Wonderland; AndrewC; aragorn; aristotleman; Avoiding_Sulla; BBell; ...
Thanks BGHater.
 
Catastrophism
 
· join · view topics · view or post blog · bookmark · post new topic · subscribe ·
 

6 posted on 10/13/2009 5:37:22 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/__Since Jan 3, 2004__Profile updated Monday, January 12, 2009)
[ Post Reply | Private Reply | To 1 | View Replies]

To: BGHater; StayAt HomeMother; Ernest_at_the_Beach; 1ofmanyfree; 21twelve; 24Karet; 2ndDivisionVet; ...

· join list or digest · view topics · view or post blog · bookmark · post a topic · subscribe ·

 
Gods
Graves
Glyphs
Thanks BGHater.

To all -- please ping me to other topics which are appropriate for the GGG list.
GGG managers are SunkenCiv, StayAt HomeMother, and Ernest_at_the_Beach
 

·Dogpile · Archaeologica · ArchaeoBlog · Archaeology · Biblical Archaeology Society ·
· Discover · Nat Geographic · Texas AM Anthro News · Yahoo Anthro & Archaeo · Google ·
· The Archaeology Channel · Excerpt, or Link only? · cgk's list of ping lists ·


7 posted on 10/13/2009 5:38:41 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/__Since Jan 3, 2004__Profile updated Monday, January 12, 2009)
[ Post Reply | Private Reply | To 1 | View Replies]

To: SunkenCiv

All your links give me a 404


8 posted on 10/13/2009 5:46:33 PM PDT by bigheadfred (NEGROMANCER!!! Run For Your LIVES!!!!)
[ Post Reply | Private Reply | To 7 | View Replies]

To: SunkenCiv

404 for me too.


9 posted on 10/13/2009 6:03:55 PM PDT by Grimmy (equivocation is but the first step along the road to capitulation)
[ Post Reply | Private Reply | To 7 | View Replies]

To: SunkenCiv
The requested document does not exist on this server.

bummer.

GREAT BEASTS PEPPERED FROM SPACE

The discovery follows on from the group's previous research which claimed a more recent space collision - some 13,000 years ago.

...The researchers reported the discovery of sediment at more than 20 sites across North America that contained exotic materials: tiny spheres of glass and carbon, ultra-small specks of diamond and amounts of the rare element iridium that were too high to be terrestrial.

The scientists also found a black layer which, they argued, was the charcoal deposited by wildfires that swept the continent after the space object smashed into the Earth's atmosphere...

10 posted on 10/13/2009 6:22:10 PM PDT by Fred Nerks (fair dinkum)
[ Post Reply | Private Reply | To 5 | View Replies]

To: bigheadfred; Grimmy; SunkenCiv

There’s an extra /focus in each of them.


11 posted on 10/13/2009 6:22:54 PM PDT by naturalman1975 ("America was under attack. Australia was immediately there to help." - John Winston Howard)
[ Post Reply | Private Reply | To 8 | View Replies]

To: naturalman1975

“There’s an extra /focus in each of them.”

Ok, assume I’m a techtard, since it’s a mostly true condition.

The extra focus, whatsat mean? Should I stare at it extra hard to make it work?


12 posted on 10/13/2009 6:25:41 PM PDT by Grimmy (equivocation is but the first step along the road to capitulation)
[ Post Reply | Private Reply | To 11 | View Replies]

To: Grimmy

Click on the link.

The page will open (with the error message saying it doesn’t exist) but the address will be in the address bar of your browser.

In that address will be a part that reads /focus/focus

Click on the address to edit out one of the /focus and now the address should take you to the page.

So

http://www.freerepublic.com/focus/focus/news/2020430/posts

which doesn’t work.

Becomes

http://www.freerepublic.com/focus/news/2020430/posts

which does.


13 posted on 10/13/2009 6:29:58 PM PDT by naturalman1975 ("America was under attack. Australia was immediately there to help." - John Winston Howard)
[ Post Reply | Private Reply | To 12 | View Replies]

To: naturalman1975

very cool. thanks.


14 posted on 10/13/2009 6:32:01 PM PDT by Grimmy (equivocation is but the first step along the road to capitulation)
[ Post Reply | Private Reply | To 13 | View Replies]

To: naturalman1975

Diamonds tell tale of comet that killed off the cavemen
Guardian ^ | 5-20-07 | Robin McKie

http://www.freerepublic.com/focus/news/1836898/posts

It works! Thanks.


15 posted on 10/13/2009 6:33:47 PM PDT by Fred Nerks (fair dinkum)
[ Post Reply | Private Reply | To 13 | View Replies]

To: naturalman1975

Work, work, work... :-)

Thanxs, Man! :-)


16 posted on 10/13/2009 7:21:33 PM PDT by bigheadfred (NEGROMANCER!!! Run For Your LIVES!!!!)
[ Post Reply | Private Reply | To 13 | View Replies]

To: naturalman1975

Wow, I did it again... [blush]


17 posted on 10/13/2009 7:34:28 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/__Since Jan 3, 2004__Profile updated Monday, January 12, 2009)
[ Post Reply | Private Reply | To 11 | View Replies]

Thanks naturalman1975.
18 posted on 10/13/2009 7:35:14 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/__Since Jan 3, 2004__Profile updated Monday, January 12, 2009)
[ Post Reply | Private Reply | To 11 | View Replies]

To: bigheadfred; Fred Nerks; Grimmy

http://www.freerepublic.com/focus/chat/2361358/posts?page=18#18


19 posted on 10/13/2009 7:36:04 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/__Since Jan 3, 2004__Profile updated Monday, January 12, 2009)
[ Post Reply | Private Reply | To 8 | View Replies]

To: SunkenCiv

Thanks but sheesh. We ain’t so lazy that we can’t delete a bit of /focus from a addy.


20 posted on 10/13/2009 7:38:45 PM PDT by Grimmy (equivocation is but the first step along the road to capitulation)
[ Post Reply | Private Reply | To 19 | View Replies]

To: SunkenCiv

Fixed it!

thanks.


21 posted on 10/13/2009 7:46:07 PM PDT by Fred Nerks (fair dinkum)
[ Post Reply | Private Reply | To 19 | View Replies]

To: Fred Nerks

My pleasure.


22 posted on 10/14/2009 3:36:41 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/__Since Jan 3, 2004__Profile updated Monday, January 12, 2009)
[ Post Reply | Private Reply | To 21 | View Replies]

To: Grimmy

Now ya tell me... ;’)


23 posted on 10/14/2009 3:36:53 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/__Since Jan 3, 2004__Profile updated Monday, January 12, 2009)
[ Post Reply | Private Reply | To 20 | View Replies]

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.

Free Republic
Browse · Search
General/Chat
Topics · Post Article

FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson