Sun Aug 25 15:11:26 1996

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Date: Sun, 25 Aug 1996 14:04:01 -0700
To: tc-list@scholar.cc.emory.edu
From: "Robert B. Waltz" 
Subject: Re: Carbon dating
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I realize this probably isn't of much interest to the list as a while,
but maybe somebody cares....

On Sun, 25 Aug 1996, Mike Phillips  wrote:

[snipping my remarks about the methods of radiocarbon dating...
 wouldn't you know that there's probably only one person on the
 list who understood what I said -- and he disagrees with me :-) ]
>
>	The reason it doesn't work is due to the underlying assumption that
>C-12, C-13, and C-14 are deposited, each at their own rate, at constant rates
>(unique to each individual isotope) over time.  Hence, the calculations depend
>on X amount of C-12 accruing in 100 years, Y amount of C-13 accruing in 100
>years, and Z amount of C-14 accruing in 100 years.  Since the ratio would be
>constant between C-12, C-13, and C-14, if this assumption was true, and since
>only C-14 decays (and the rate of that decay is known) then all the researcher
>need do is adjust the amount of C-14 in the sample back to it's "original"
>ratio by using the rate of decay, and determining the amount of time that
>decay
>was in process.
>	The system fails because C-12, C-13, and C-14 are not deposited at the
>same rate in the atmosphere in any given period, i.e., solar flares, floods,
>meteor strikes, climactic changes, volcanic activity, plate shifts, etc., all
>may effect the rate at which C-12, C-13, and C-14 are 'made', hence
>'assimilated', hence, 'occur.'  The underlying assumption of constancy is the
>weak link.

But if the effect is not constant, how does one decide how much to correct --
particularly for early periods when we have no dated artifacts? Also,
doesn't this mean that there will be *geographic* variations in C-14
count?

I'm not saying you're wrong (though this strikes me as a theory supplied
to explain away a failed method); I'm just asking how one can possibly
apply the revised method?

I would also remind people that this isn't really important to the point;
the crucial matter is that radiocarbon dating can only date to the
nearest century or so, and so is not much use in precisely dating
manuscripts. This has nothing to do with theoretical problems; this
is based simply on our inability to measure the amount of C-14 with
absolute precision.

Bob Waltz
waltzmn@skypoint.com

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