[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
orion-list Radiocarbon
[The following text is in the "iso-8859-1" character set]
[Your display is set for the "ISO-8859-8" character set]
[Some characters may be displayed incorrectly]
Dear orioners: for those following the issues with 63 BCE
and the radiocarbon dates I suggest in terms of method that
the 63 BCE terminus hypothesis be evaluated separately
in terms of (a) all non-radiocarbon grounds, and (b)
radiocarbon data alone. Secondly, as a provisional term the
five radiocarbon dates whose 2-sigma ranges are entirely
post-63 BCE might be termed "apparent evidence against a
63 BCE terminus". The lab-reported dates are actual, not
apparent, but the conversion of these lab reported dates to
an historical judgment is what is at issue.
Third, for the 5 clearly post-63 BCE AMS dates, there are
basically three possibilities: (a) the 63 BCE terminus is wrong;
(b) there is some anomaly in the calibration curve, i.e. a
regional effect; or (c) contaminated dates.
After further study and discussions with a radiocarbon scientist,
I'm convinced now that "b" above is the least likely of the three
possibilities. The very possibility of the existence of a true
"regional offset" itself is not secure. Apparently, studies from
the days of atmospheric nuclear testing appear to show
complete air mixing in the northern hemisphere troposphere of
three months, not 10-20 years; which would mean a true
regional offset (> 3 months) should not be possible. There are
location-dependent offsets measured and reported, but just
why these occur is subject to different possible explanations,
e.g. lab offsets or ecosystem factors. In any case offsets of
this nature apply to the radiocarbon measurement numbers
themselves rather than to calendar years. All of this supports
what Tim Jull said earlier concerning regional offset being a
minor or insignificant factor.
It may therefore in the end be that there are only two, rather
than three, real possiblities: either the 63 BCE terminus
is wrong, or the five post-63 BCE AMS dates have been
inaccurately dated. Here I may owe Tom Simms an apology.
He kept talking about sample contamination and I assured
him the problem was likely minimal, at some unknown low
level of incidence but not likely to be a major factor. Some
research underway, to be reported when completed, suggests
that the potential problem with scrolls AMS dates from
inadequate sample pretreatment methods may be worse than
thought. (The good news is the problems, once identified, are
amenable to solutions.) It is again as Tim Jull said: the only
way to find out is to do more measurements and find out. I do
not control the timing of the upcoming battery, but it appears
likely that a third battery of AMS dates may be accomplished
within the next 3-5 months.
As a final comment on the five "problem" AMS dates for the
63 BCE terminus theory: on the assumption that the AMS dates
are accurate and the palaeographic datings used in the Qumran
field are also accurate, it would be expected that all five of the
post-63 BCE 2-sigma dates should be "Herodian" hands. But if
the five "problem" dates are representing problems in the
radiocarbon measurements (or if the palaeographic dating
assumptions are invalid) a random mixture of "Herodian" and
non-"Herodian" scribal hands would be predicted. In fact the
second pattern, and not the first, is what we see. Of the five
dates, three are texts with "Herodian" hands, and two are
"Hasmonean" hands. These two are:
4Q266 D(a): 2sigma (95% confidence): 44 BCE-129 CE
1sigma (68% confidence): 4-82 CE
4Q521 MessApoc: 2sigma (95% conf.): 49 BCE-116 CE
1sigma (68% conf.): 39 BCE-66 CE
These two texts have published palaeographic "datings" of
pre-50 BCE and c. 100-80 BCE, respectively.
Therefore while if any of the five "problem" dates are securely
corroborated and verified this will essentially be fatal to a
63 BCE terminus, and if one of them (4QpPsA) is verified
that will provide the first evidence for 1st century CE Qumran
text scribal activity, at the same time if two other of the five
dates (4Q266, 4Q521) are corroborated and verified this should
also eviscerate confidence in the high-precision palaeographic
dating system currently in common use. More is at stake
than just the 63 BCE terminus in this. In any case, these
uncertainties will not be forever. Radiocarbon is going to
go one way or the other on these questions.
Greg Doudna
Copenhagen
For private reply, e-mail to Greg Doudna <gd@teol.ku.dk>
----------------------------------------------------------------
To unsubscribe from Orion, e-mail to majordomo@panda.mscc.huji.ac.il with
the message: "unsubscribe Orion." For more information on the Orion Center
or for Orion archives, visit our web site http://orion.mscc.huji.ac.il.