Re: Brazilian Findings Spark Archeological Debate
- From: "Jean" <jean.lenior@xxxxxxxxxx>
- Date: Mon, 31 Aug 2009 18:19:02 +0200
Eric Stevens a écrit dans le message ...
On Mon, 31 Aug 2009 10:58:00 +0200, "Jean" <jean.lenior@xxxxxxxxxx>is
wrote:
Eric Stevens a écrit dans le message ...
On Mon, 31 Aug 2009 09:39:03 +0200, Peter Alaca
<p.alaca@xxxxxxxxxxxxxxxx> wrote:
crunch <pchristainsen@xxxxxxxxx> 31/08/2009 07:59 wrote:
On Aug 31, 1:01 am, Eric Stevens <eric.stev...@xxxxxxxxx> wrote:
On Sun, 30 Aug 2009 20:41:48 -0700 (PDT), Tom McDonald
<kilt...@xxxxxxxxx> wrote:
On Aug 30, 10:35 pm, Eric Stevens <eric.stev...@xxxxxxxxx> wrote:
On Sun, 30 Aug 2009 16:58:35 -0700 (PDT), crunch<snip>
<pchristain...@xxxxxxxxx> wrote:
Brazilian excavators, led by Niede Guidon, claim
to have proved the existence of the oldest
Americans. Guidon claims that charcoal she says
is the remnant of camp fires has been carbon
dated to 50,000 years ago.
Now that's a considerable stretch for carbon dating. 45,000 years
..br/fumdhamentos7/cronologias.asp&ei=b2WbStOWCcO1lAeVqJC7BQ&sa=X&oi=translathttp://translate.google.com/translate?hl=en&sl=pt&u=http://www.fumdham.orgnormally considered the limit.I've read that, with good samples and AMS (and other?) technology,
reasonable dates can be derived back ~60,000 ybp.
<snip>
The URL that Crunch gave was dated 2008, for which date I would agree
with your comments. However, the original of the article may be found
athttp://www.cabrillo.edu/~crsmith/pedrafurada.htmlwhich is dated
2000. I don't think the limits of RC technology had been extended at
that date.
Eric Stevens- -
e&resnum=4&ct=result&prev=/search%3Fq%3D%2522Peopling%2BBrazil%2Btook%2Bplac
e%2Bmuch%2Bearlier%2Bthan%2Bin%2BNorth%2BAmerica%253F%2522%26hl%3Den%26safe%
3Doff%26sa%3DG
of
or http://tinyurl.com/mu3jd4
Why use Google Translate for what is already in English?
And what is it you want us to read?
In any case, it is 2006. To be relevant to to a paper dated 2000 I
would like to see a cite for the technique dated 1998 or thereabouts.
Building Trusted timelines: Methods of Physics apply to the
Archeology
-14C-AMS as a tool for archaeological investigation: Implications for
Human Settlement in South America - Guaciara M. -14C-AMS as a
tool for archaeological investigation: Implications for Human
Settlement
in South America - Guaciara M. Santos et al
David Christainsen
Just dumping some lines without knowing what is behind them.
As usual.
What does it say about the limits of carbon dating, Carl?
Eric Stevens
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/cardat.html
"Copyright 1999 by Carl Rod Nave,"
"The low activity of the carbon-14 limits age determinations to the order
100,00050,000 years by counting techniques. That can be extended to perhaps
years by accelerator techniques for counting the carbon-14 concentration."
Wikipedia says at http://en.wikipedia.org/wiki/Radiocarbon_dating
"As of 2007[update], the limiting age for a 1 milligram sample of
graphite is about ten half-lives, approximately 60,000 years"
In the year 2000 it would have been no better than 50,000 years and at
that point one is attempting to determine the difference between
nearly nothing and almost nothing. By the time you were claiming
50,000 years you were saying something between 50,000 and 'so old I
don't really know'. That's why I thought claiming 50,000 years as a
precise figure was 'bit of a stretch'. Even 45,000 is highly
uncertain. The article you cited above touches on the calibration
problem.
Eric Stevens
Wikipedia is on line encyclopedia meant for use by joe six pack.
It is not a reliable science source nor was it intended to be .
JL
.
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