Mon Aug 26 16:14:37 1996

From owner-tc-list  Mon Aug 26 16:14:37 1996
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Date: Mon, 26 Aug 1996 16:13:26 -0400 (EDT)
From: "James R. Adair" 
To: tc-list@scholar.cc.emory.edu
Subject: Re: Carbon dating
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As others in this discussion have already noted, radiocarbon dating is by 
no means a straightforward exercise.  Furthermore, the dates it gives may 
not be precise enough to answer the questions we may want to ask.  The 
following points should be kept in mind by anyone using radiocarbon dates.

1. If possible, radiocarbon dates should be checked against dates 
determined by some other method (e.g., paleography, dendrochronology 
[tree rings], another radio-isotope dating method).  Dates may also be 
checked against the "known date" that an event occurred.  However, many 
people are calling for a reassessment of some of these "known dates" (cf. 
Peter James et al., _Centuries of Darkness_, which puts forward the case 
for compressing the period generally dated from ~1500 to 1000 in Europe 
and the Middle East), so they should be used with caution.

2. C14 was not distributed with perfect regularity over time, so
adjustments to the "Apparent Radiocarbon Age" need to be made.  Scientists
working at radiocarbon testing facilities, however, have made extensive
measurements of thousands of samples, so the amount of adjustment
necessary for a particular sample can be approximated fairly well. 

3. The amount of C14 in the immediately surrounding environment varies 
widely depending on whether an organism lived on land or in the ocean.  
There are other complicating factors as well related to the "radiocarbon 
reservoir."

Despite the complexity involved in measuring radiocarbon dates, they are
probably about as accurate as most other dating schemes for ancient
materials, particularly when they are calibrated against the results of
other methods.  It is not a methodologically sound procedure to reject the
results of a method just because the method itself is complex or the
results do not correspond with our preconceived notions of dating.  On the
other hand, we need to be aware of the difficulties inherent in the
method.  For additional online information, see the Radiocarbon Web-Info
page at http://www2.waikato.ac.nz/c14/webinfo/index.html. 

Jimmy Adair
Manager of Information Technology Services, Scholars Press
    and
Managing Editor of TELA, the Scholars Press World Wide Web Site
---------------> http://scholar.cc.emory.edu <-----------------

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