Archaeologica.org

The Younger Dryas would have been a major stress on species survival and rendered NA virtually uninhabitable.

At that time, Canada was already glaciated, although the ice had been in the process of melting. Much of the area of the current US is on the same latitude as the Sahara desert and had thriving flora and fauna during the ice age. The Younger Dryas is usually described as an abrupt return to Ice Age conditions. So I don't think the YD was responsible for extinctions in NA.

Regarding South America, I haven't read that it was already cooling prior to the YD. I'd like to read it if you have a link Monk.

Thanks.

http://en.wikipedia.org/wiki/Younger_Dryas

There's one for you Beag.

"If the event occurred as advertised, then the Northern Hemisphere temperature drops would have taken somewhat less than three years and been more extreme than let on in the article."

What Firestone lays out in his book is that beyond the terrestrial fury, dust/debris from the explosion was tossed into the atmosphere and surrounded the globe, just like what happened with Pinutubo but much worse. This would seem to make the entire globe come down in temperature rather quickly. It is going to be interesting to see how this plays out. I have never heard of a black mat turning up in Europe.

Fascinating is how Folsom points fit into all this. The best knappers have considered it extremely hard to replicate. It always looked like it was a natural extension of the Clovis flute. According to this new scenario, there seems to have been a long gap between the two techs, like a millenia or so? Were these the great ancestors of the Clovis or a different group?

Chris

Beagle wrote:Regarding South America, I haven't read that it was already cooling prior to the YD. I'd like to read it if you have a link Monk.

Wiki again:
http://en.wikipedia.org/wiki/Antarctic_Cold_Reversal

This pattern of climate decoupling between the Northern and Southern Hemispheres, and of "southern lead, northern lag," would manifest in subsequent climate events. The cause or causes of this hemispheric decoupling, of the "lead/lag" pattern, and of the specific mechanisms of the warming and cooling trends, are subjects of study and dispute among climate researchers. The specific dating and intensity of the Antarctic Cold Reversal are also under debate.[5]

The onset of the ACR was followed, after about 800 years, by an Oceanic Cold Reversal in the Southern Ocean.

Several papers are on the web but many require memberships to read. The synchronicity or as it turns out asynchronicity of the north/southern hemispheric weather patterns is a subject of ongoing study and computer modeling.

hardaker wrote:"If the event occurred as advertised, then the Northern Hemisphere temperature drops would have taken somewhat less than three years and been more extreme than let on in the article."

What Firestone lays out in his book is that beyond the terrestrial fury, dust/debris from the explosion was tossed into the atmosphere and surrounded the globe, just like what happened with Pinutubo but much worse. This would seem to make the entire globe come down in temperature rather quickly. It is going to be interesting to see how this plays out. I have never heard of a black mat turning up in Europe.

Fascinating is how Folsom points fit into all this. The best knappers have considered it extremely hard to replicate. It always looked like it was a natural extension of the Clovis flute. According to this new scenario, there seems to have been a long gap between the two techs, like a millenia or so? Were these the great ancestors of the Clovis or a different group?

Chris

Chris, although I have no expertise in flake technology, the similarities between Clovis and Folsom are pretty remarkable. It's hard not to believe that they were somehow connected.

The synchronicity or as it turns out asynchronicity of the north/southern hemispheric weather patterns is a subject of ongoing study and computer modeling.

Thanks Monk and Digit. Agreed on the asynchronicity. Beyond that I don't have a clue as to why the Southern Hemisphere would begin a cool down during a period of northern warming. It will take the scientists a bit longer to unravel that one I expect.

Hi Beagle,
I think they must be related. Folsom took Clovis to an entirely new level. My wonderment has to do with the gap of years in between the two. Folsom is listed at 10,500 bp -- and Clovis was 12,900 bp? Is there a 2400 year gap, or is the 10,500 bp date in need of a calibration?
Chris

Folsom date given here.

http://www.sciencedirect.com/science?_o ... c07fe4591a

Chris, I've read about the calibration issue, and have heard a couple of reasons why current dating by C14 is inaccurate. I wish somebody would figure it out soon and just tell me how old something is.

You've just cited an excellent example of the confusion about the issue.

Hi Beagle,
I think they must be related. Folsom took Clovis to an entirely new level. My wonderment has to do with the gap of years in between the two. Folsom is listed at 10,500 bp -- and Clovis was 12,900 bp? Is there a 2400 year gap, or is the 10,500 bp date in need of a calibration?
Chris

Chris, actually I don't believe there was much of a gap between Clovis and Folsom, if at all. Mike Waters' new dates for Clovis are 11,050RCya to 10,800RCya. That equates to 13,050bp to 12,800bp ... a very tight range of 250 years.

Source: http://www.sciencemag.org/cgi/content/a ... /5815/1122

To convert radiocarbon years to bp I used this link and extrapolated the numbers:

Source: http://www.unc.edu/~rowlett/units/scale ... carbon.htm

The initiation of the Younger Dryas is dated to the same time as the demise of Clovis at 12,800bp.

Source: http://www.ldeo.columbia.edu/res/pi/arch/examples.shtml

Folsom points may have come on the scene directly after Clovis.

Source: http://argonaut.arizona.edu/history.htm

You are probably looking for this type of chart as lifted from the PNAS article:



Source: http://www.pnas.org/cgi/content/full/95/24/14576

However, even the PNAS article has Clovis in the wrong time-frame.

Hi Cognito,
Thanks for the clarification. 250 years, given the dating techniques, is very close. Good. I feel better. It seemed a pretty drastic gap.
Chris

I agree. Nice links there Cogs. I looked through 'em this morning.

http://news.nationalgeographic.com/news ... tinct.html

Debate has heated up over a controversial theory that suggests huge comet impacts wiped out North America's large mammals nearly 13,000 years ago.

The hypothesis, first presented in May 2007, proposes that an onslaught of extraterrestrial bodies caused the mass extinction known as the Younger Dryas event and triggered a period of climatic cooling.

A new National Geographic article about the comet theory. Some pros and cons are examined. New papers are being prepared.

Beagle wrote:A new National Geographic article about the comet theory. Some pros and cons are examined. New papers are being prepared.

A recapitulation of stories we have already discussed.
Thanks, Beags.

hardaker wrote:What Firestone lays out in his book is that beyond the terrestrial fury, dust/debris from the explosion was tossed into the atmosphere and surrounded the globe, just like what happened with Pinutubo but much worse. This would seem to make the entire globe come down in temperature rather quickly. It is going to be interesting to see how this plays out. I have never heard of a black mat turning up in Europe.

But the scenario is of course a familiar one. The same, in varying degrees of intensity, happened at the 65Myo BP dino extinction event, or the Toba eruption 75Kyo BP (http://en.wikipedia.org/wiki/Toba), which deposited 6 meters (20 feet) of ash that possibly cover HE and his boats, caught by the eruption during their odyssey to Oz... (like Pompeii and Herculaneum).

Forum Monk wrote:

Beagle wrote:A new National Geographic article about the comet theory. Some pros and cons are examined. New papers are being prepared.

A recapitulation of stories we have already discussed.
Thanks, Beags.

Yeah, when I looked in our newsroom and saw that Nat'l Geo had run this story, I was a little surprised since I thought the theory had gotten shelved somewhere. I'm happy to see that it's still under consideration and study.