[ RadSafe ] RE: Queen's helps produce archaeological 'time machine'

Sun Feb 14 07:55:06 CST 2010

Dear Roy:

As a geologist dealing with ore deposits considerably older than 50,000
years, I've not been able to use radiocarbon dating and usually stick to
uranium-series data.  As the title suggests, the main benefactors of this
research & discussion will be archeologists.  I'm usually more concerned
with radiometric equilibrium within sandstone uranium ISR deposits as well
as differential isotopic leachability of ore bodies when exposed to
different leach solutions (e.g. especially U238 - U234). As the article
mentions, "It has taken nearly 30 years for researchers to produce a
calibration curve this far back in time. Since the early 1980s, an
international working group called INTCAL has been working on the project."
I remember having coffee every day for 8 years with the Nuclear Data Section
of the IAEA, and the intense effort and intercalibration exercises with
numerous laboratories including Seibersdorf in preparing their series of
databases.  I hope that INTCAL will be equally successful.  I would
certainly hope that INTCAL has been through a similar critical review.

Perhaps Lisa McElroy might join in this discussion and explain the
significance of the new calibration data and methods  I'm sure that much of
the discussion will be related to potential contamination of modern
materials, sampling methodology, QA/QC, and intercalibration resulting in
the current database.

Dan ii

--
Dan W McCarn, Geologist
2867 A Fuego Sagrado
Santa Fe, NM 87505
+1-505-310-3922 (Mobile - New Mexico)
 <mailto:HotGreenChile at gmail.com>  <mailto:HotGreenChile at gmail.com>
HotGreenChile at gmail.com (Private email)

  _____  

From: *** ****** [mailto:royherren2005 at yahoo.com] 
Sent: Saturday, February 13, 2010 22:24
To: Dan W McCarn
Cc: radsafe at radlab.nl
Subject: Queen's helps produce archaeological 'time machine'

Dan,

    Its not entirely clear from the following articles just exactly how the
"new calibration curve" will change our perspective of the historic passage
of time.  It will be interesting to see how much smaller the +/- range will
be on estimates of the age of specimens.  Will this new calibration curve
cause a "re-evaluation" of older data?  What is your take on this news?

Roy

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http://www.qub.ac.uk/home/TheUniversity/GeneralServices/News/PressReleases/T
itle,183016,en.html

Queen's helps produce archaeological 'time machine' 

Researchers at Queen's have helped produce a new archaeological tool which
could answer key questions in human evolution.

The new calibration curve, which extends back 50,000 years, is a major
landmark in radiocarbon dating - the method used by archaeologists and
geoscientists to establish the age of carbon-based materials. It could help
research issues including the effect of climate change on human adaption and
migrations. 

The project was led by Queen's University Belfast through a National
Environment Research Centre (NERC) funded research grant to Dr Paula Reimer
and Professor Gerry McCormac from the Centre for Climate, the Environment
and Chronology (14CHRONO) at Queen's and statisticians at the University of
Sheffield. Ron Reimer and Professor Emeritus Mike Baillie from Queen's
School of Geography, Archaeology and Palaeoecology also contributed to the
work.

The curve called INTCAL09, has just been published in the journal
Radiocarbon. It not only extends radiocarbon calibration but also
considerably improves earlier parts of the curve.

Dr Reimer said: "The new radiocarbon calibration curve will be used
worldwide by archaeologists and earth scientists to convert radiocarbon ages
into a meaningful time scale comparable to historical dates or other
estimates of calendar age.  

"It is significant because this agreed calibration curve now extends over
the entire normal range of radiocarbon dating, up to 50,000 years before
today.  Comparisons of the new curve to ice-core or other climate archives
will provide information about changes in solar activity and ocean
circulation."

It has taken nearly 30 years for researchers to produce a calibration curve
this far back in time. Since the early 1980s, an international working group
called INTCAL has been working on the project. 

The principle of radiocarbon dating is that plants and animals absorb trace
amounts of radioactive carbon-14 from carbon dioxide in the atmosphere while
they are alive but stop doing so when they die. The carbon-14 decays from
archaeological and geological samples so the amount left in the sample gives
an indication of how old the sample is. 

As the amount of carbon -14 in the atmosphere is not constant, but varies
with the strength of the earth's magnetic field, solar activity and ocean
radiocarbon ages must be corrected with a calibration curve.

Most experts consider the technical limit of radiocarbon dating to be about
50,000 years, after which there is too little carbon-14 left to measure
accurately with present day technology.

Further information on the work of Queen's Chrono Centre can be found online
at  <http://chrono.qub.ac.uk/> http://chrono.qub.ac.uk/

Media inquiries to Lisa McElroy, Press and PR Unit. Tel: +44 (0)28 9097 5384
or email  <mailto:lisa.mcelroy at qub.ac.uk> lisa.mcelroy at qub.ac.uk . 
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http://digitalcommons.library.arizona.edu/holdings/journal?r=http://radiocar
bon.library.arizona.edu/

http://www.radiocarbon.org/index.html

http://www.radiocarbon.org/IntCal09.htm

http://c14.arch.ox.ac.uk/embed.php?File=calibration.html

http://thesga.org/2010/01/new-radiocarbon-calibration-curve-intcal09/