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Re: orion: DSS pottery/C14

Virgil Brown asks a relevant question:
> 	Most of the DSS were found near pottery/jars that were veri-
> similar to pottery found at Khirbet Qumran. The Donceels were working 
> a more detailed analysis of this pottery but I have not heard what
> results they may have reached. Can anyone help?
> 	The ramifications of this are obvious. Regardless of whether
> a scroll may be C-14 dated to the middle of the 1st century BCE, if 
> the pottery in which it was placed may be dated to a half of a 
> century later, then the latter is the date the scroll was deposited 
> in the caves.

So far as I understand the Donceels study is at a standstill and 
there is no sign of life on Qumran pottery study known to me.
On dating, your logic is correct that if the wide-mouthed jars in the 
caves and at Qumran (since these seem linked) can be dated, this is good 
information for dating the deposits of the texts.  But the problem is 
in dating those jars.  Typological analysis is not going to do it since 
these jars according to reports typologically work well from 2nd BCE 
to probably into the 1st CE.  An early Herodian context find of 2 or 3 
of these jars at Jericho simply attests they are in currency at that time, 
and does not date the ones used at Qumran.  Clay jars are amenable 
to dating by several scientific means, but so far this seems not to have 
been done on any of these jars.
 
Analysis of the archaeology of Qumran itself seems the best shot on 
present information for getting precision dating of the use of jars 
at Qumran.  J. Magnes and De Vaux thought there were period II uses 
of these jars.  De Vaux's notes in Humbert and Chambon 1994 read to me 
like all of the big jars went into floors in the original construction of the 
site early 1st BCE.  None of these wide-mouthed jars at the site of Qumran 
were found other than buried in floors in corners of rooms.    

And from Tom Simms:
>    Then there was the bland notice that acid washes might work. 
>    Horrors! The leather trappings of King Tut's horses literally

You might take a look at Sheridan Bowman, _Radiocarbon Dating_, 
1990 or one of the other references cited earlier, or either of the two 
published scrolls lab reports in _Radiocarbon_ for information on 
cleaning procedures which would replace your speculation with 
information.  The basic procedure, used in labs throughout the world, 
is hydrochloric acid, then sodium hydroxide, then hydrochloric 
acid.  This is supplemented with other treatments and techniques, such 
as solvents and ultrasound, according to lab judgments on what is needed 
in light of possible contaminants.  You mentioned that acid is 
harmful to animal skin.  While true, it is also irrelevant, since the sample 
is going to be converted to carbon and destroyed anyway.  

On your point that all scrolls dates could be offset equally by the same 
contamination, this might be the case for a small number of dates, but 
when you get many dates from widely diverse samples agreeing on 
the same 14C dates (in this case many scrolls are 14C dating 1st 
BCE), this convergence is a strong argument in favor of a "real" date 
being reflected.  Contaminated samples give results all over the 
map, rather than agreeing in close consistency.  Furthermore, take 
note of the technique used at Zurich, reported in both the _Atiqot_ 
and _Radiocarbon_ reports: by using two levels of cleaning on 
different subsamples from the same sample and comparing results, if 
there is contamination there are likely to be different 14C 
measurements due to different effects of the cleaning.  Of 14 scrolls 
samples Zurich dated, only one (4QTQahat) showed such a difference 
in this procedure giving a clear sign of contamination. 

The spectre you paint of possible widespread, catastrophic 
contamination affecting all scrolls dates is not in agreement with the 
following as well: The 14C dates for 4QSam(c) at Zurich and 1QS at 
Tucson, different texts but with the same scribes, were in agreement.  
Six out of seven internally-dated papyrus texts between the two labs 
gave 14C dates in which the true dates of those texts were within the 
measured and calibrated two-sigma 14C date ranges. These examples 
do not support a notion of widespread contamination affecting large 
numbers of 14C scrolls dates.  The problem is serious when it is a 
factor, but its incidence seems to be low.  Naturally, both we and the 
labs want to find ways to reduce this incidence to zero.

Greg Doudna
Copenhagen