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Re: orion-list Radiocarbon

On Mon, 11 Oct 1999 14:45:13 +0200, gd@teol.ku.dk writes:
>Returning to the topic of radiocarbon dating and the Scrolls,
>there is no way the existing data on the texts, if accurate,
>can be harmonized with a 63 BCE terminus for the scrolls. 
>Although I suggested this in a previous post, if it was not
>direct enough I wish to make the point explicit here.  The
>calibration curve between 55 BCE and 85 BCE is essentially
>flat, at about 2075 +/- 20 throughout these three decades. 
>This means any texts from c. 85-63 BCE should all yield
>the same measurement, c. 2075 +/- 20, within margins of
>error.  (Older than 85 BCE the calibration curve rises.)  Any
>texts which measure significantly less than c. 2075 +/- 20
>are therefore indicating younger than 63 BCE.

   Thank you for supplying these numbers, Greg.

   I have summed them and given averages for 
                      _                _
   both the averages (X) and the S.D. (x).

  Then I have provided Before Present (BP) and CE dates, assuming
  they were tested in 1990.
>Five texts did measure significantly below 2075 +/- 20. 
>These are:
> 1QH                 1979 +/- 32
> 4Q266 D(a)          1954 +/- 38
> 4Q258 S(d)          1823 +/- 24 (#1)
>                   / 1964 +/- 45 (#2)
> 4Q171 pPs(a)        1944 +/- 23
> 4Q521 MessAp        1984 +/- 33
>                 _         _
>                 X = 1941  x = 31 
>             _   _            _   _  
>          So X + x = 1972 and X - x = 1911    
>         Then BP when P = 1990 is
>                _
>             BP X = 39 CE                    
>            _   _             _   _
>    Then BP X + x = 18 CE, BP X - x = 79 CE  
>It can be seen that these numbers are not consistent with the
>calibration curve level at 85-55 BCE.  These cannot be explained
>as random scatter.  On the hypothesis that many or even most
>of the 19 Qumran texts had true dates in the years 85-55 BCE
>(and none younger) one would expect somewhere between
>only 0 and 1 texts to give numbers like the above--but not five.
>Five of this kind of number is about 4-5 too many.

   IMO, the subset dates don't explain a 68 CE date of deposit.
   As the data stands, the subset argues for one of two
       1.  A second deposit after 63 BCE, or, since no evidence
           I know of has been found suggesting that;
       2.  The sample was contaminated during recovery and treatment.

   Since neither explanations seem capable of resolution, then
   further testing with wider choice of sample is the only option.
   Given the treatment of the material since recovery, it may be 
   neccessary to clean some samples to destruction and lose those
   samples in order to minimize the effect of contamination.

   I'm interested in seeing what Prof.Jull says to your Q's, Greg.
   It will be useful, I'm sure.

>(The reason I spoke in earlier discussions on Orion in terms
>of possible compatibility between 63 and these dates was
>because of an error in interpretation of the regional offset issue.
>I was using calendar years instead of radiocarbon measurement
>years for the c. +/- 20 location-offset possibility.  This is a
>technical point and if anyone is truly curious as to the details
>of my error contact me offlist.  It can be seen from the numbers
>above that even a 20 offset will not bring the five dates above
>into possible agreement with c. 2075 +/- 20.)
>The conclusion is: there is no reconciling the above data with 63
>BCE on the assumption that these are accurate measurements.
>But now I wish to address a question to Tim Jull, if he is listening.
>In fact, although many in the Qumran field perceive differently,
>there is no basis to know of post-63 BCE text activity among the
>Qumran texts other than these radiocarbon dates.  There is a
>story that seems plausible to many surrounding 68 CE, but that
>is as strong as the positive case is for post-63 BCE.  It therefore
>becomes critically important to evaluate the meaning of this
>radiocarbon data rightly.
>You have rightly noted that it is improper to reject data points
>without cause.  Yet if I may turn the question around, is it safe
>to believe all unexcluded data points in terms of deep and
>far-reaching historical conclusions?  Here is the problem. 
>Among the 19 Qumran texts given AMS datings, 2 of these
>(4QTQahat at Zurich; 4QSd at Tucson) appear to have had
>problems in their datings.  In neither case was the contam-
>ination, if that is what it was, that caused these results
>detectable or visible to either lab under microscope.  If this
>is the case with 2 datings, what is the proper evaluation of
>the remaining 17 in terms of drawing historical conclusions?
>How does one determine the latest date of floruit of an
>archaeological assemblage or floruit or cluster from a battery
>of AMS datings?  (In this case, the latest known Qumran
>text production.)  What are the right methods to use and
>what kind of "latest-date" estimate based on the existing
>Qumran AMS data is produced by correct methods?   
>Greg Doudna
>Gregory L. Doudna
>Reseach Associate
>U. of Copenhagen Dead Sea Scrolls Initiative
>K=F8bmagergade 44-46                             tel: (45) 35 32 36 34
>1150 K=F8benhavn K                               fax: (45) 35 32 36 52
>DENMARK                                        email: gd@teol.ku.dk


Tom Simms

For private reply, e-mail to Tom Simms <tsimms@mailserv.nbnet.nb.ca>
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