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Re: orion-list Radiocarbon
> From email@example.com Sat Aug 28 00:09:51 1999
> >Hence a radiocarbon
> >date after 63BC indicates that the material the scrolls are made from
> >was still alive after 63BC and thus could not have been deposited
> >on or before that date.
> Nope. The dates are the LATEST possible. Since we have NO
> protocols showing how the effects of contamination were taken
> into account we must assume these are the LAST dates possible.
> IOW, tests done on uncontaminated samples would show EARLIER
You seem to be questioning the underlying theoretical understanding
of the method here. In a living system the ratio of C-14 to C-12
is in equilibrium with the environment. Once the system is dead
there is no mechanism to maintain that equilibrium hence the ratio
of C-14 to C-12 changes as the C-14 decays. But if I understand your
argument correctly you are saying:-
(1) The equilibrium state is maintained until deposit.
(2) Contamination in modern times makes the samples appear younger.
I don't think (1) is right. If this is what you are claiming can you
explain a mechanism whereby the C-14/C-12 ratio in the scrolls are
kept in equilibrium with the environment after the material is no
The problem of (2) is supposed to be addressed by the cleaning of the
> Some, possibly, but each present serious questions. There are
> FOURTEEN others earlier than 63 BC. Unless you can show evidence
> of multiple deposits - which would help explain the dating dif-
> ferences - you must consider the whole deposit.
But this assumes (1) above. I think the *method* of radiocarbon
dating determines the date of the death of the organic material
on which the scrolls were written. A simpler explanation for
the different dates is that the scrolls were "manufactured" over
a lengthy period of time.
> You seem to have ignored my layman's argument showing how rapidly
> contamination can skew results.
> Again, you fail to consider that the dates reported are the
> latest for each artifact, not the earliest. Until the contamin-
> ation issue is fully addressed, you're stuck with what's there.
I haven't failed to consider this, at this point I don't believe it.
Provide me with a mechanism to keep the C-14/C-12 ratio in equilibrium
with the environment and I'll come round to your point of view.
Yes, the contamination issue is real, but on this I have to bow to the
superior knowledge and experience of the AMS people.
Bill Rea, Information Technology Services, University of Canterbury \_
E-Mail b dot rea at its dot canterbury dot ac dot nz </ New
Phone 64-3-364-2331, Fax 64-3-364-2332 /) Zealand
Unix Systems Administrator (/'
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