Subject: Re: Carbon dating

From: [email-masked]
Date: Sun, 25 Aug 1996 19:14:56 -0400

In a message dated 96-08-25 18:26:05 EDT, Dave Washburn wrote:

<< 
 I believe his point was that the generation and uptake of C-14 in 
 relation to other carbon isotopes is affected by these factors (as 
 opposed to its decay rate, which you correctly point out is a 
 constant nuclear process), and hence we can't really assume that 
 quantities of C-12, C-13 and C-14 will have started out equal.  And 
 without that equality factor, C-14 dating is on even less certain 
 footing than we thought it was.
 
 I'm not enough of a molecular scientist to say whether I agree with 
 this assessment, I just wanted to point out that this is what I 
 understood him to be saying.  >>

I have read a couple of research reports that compare C-14 dates with
tree-ring dates for bristle-cone pine trees. The evidence supports the 
fact that the level of C-14 in the atmosphere fluctuates over time,
and that C-14 levels were significantly lower in remote antiquity.

James D. Price
==================================================
James D. Price, Ph.D.
Prof. of Hebrew and OT
Temple Baptist Seminary
Chattanooga, TN 37404
e-mail [email-masked]
==================================================

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From: Vincent Broman <[email-masked]>
Date: Mon, 26 Aug 96 09:55:18 PDT

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There is a little confusion about who adjusts C-14 dates and how.
The order of events goes like this
 a. People do C-14 dating assuming constant production of C-14 in
    the upper atmosphere by cosmic rays.
 b. They eventually see some discrepancies compared to known dates of
    artefacts, too large to be explainable as isotope measurement error.
 c. They _estimate_ the nonconstant rate of C-14 formation by fitting
    measurements to known dates.  The variation is not huge.
    This gives an adjusted scale of concentrations <-> dates.
 d. They validate the estimates by tests of new known-date artefacts
    not included in the curve fitting process.
    After this point no more "adjusting" of dates occurs.
 e. They use the new validated curves, which give more accurate
    dates than before, and they occasionally scratch their heads
    over unrepeatable anomalies, just like in any other science.

Anyone who fudges his data by "adjusting" a C-14 date just to
fit some a priori theory of his (and admits it) gets laughed
out of a job, I imagine.

Vincent Broman             Email: [email-masked]                    =   o     
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