Re: Problems with the radio carbon dating of the Newport Tower


"Eric Stevens" <eric.stevens@xxxxxxxxx> wrote in message
news:v93el3dlop54grbnmiq7espj0vv1b5r7t0@xxxxxxxxxx
On Wed, 5 Dec 2007 10:04:37 -0500, "Steve Marcus"
<smarcus_spamout_@xxxxxxx> wrote:


"Eric Stevens" <eric.stevens@xxxxxxxxx> wrote in message
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On Tue, 4 Dec 2007 20:02:59 -0500, "Steve Marcus"
<smarcus_spamout_@xxxxxxx> wrote:

You clearly don't know what they did. You are not aware of the
techniques they used to separate old -CO3 from new -CO3. In fact I
strongly suspect you don't know a damned thing about what they did.

Are you seriously contending that they could accurate calibrate those
chemicals? Or that they can know for a fact the source of the shells
used
in the mortar (if any), and to what extent the original mortar was mixed
using sea shells znd to what extent lime was obtained from other
sources?
All of these things will have an effect on the percentages of the
carbonate
and hence the radiocarbon dating.

Go read their paper you ignorant clown.

Then hang your head in embarrasment. :-(

This is from a prior post of yours:

Yep. The same post with which I started this thread.

http://groups.google.com/group/sci.archaeology/msg/8a71d73bd19f0056?dmode=source
:

"The team which C14 dated the Newport Tower (Dr Hogne Junger of the
University of Helsingfors and Jogen Siemonsen) made use of a technique
which
drove off the old and new CO2 in two separate streams. I am not able to
comment on this although I understand the method is contentious in that
it
is highly reliant on the skill of the operator. For the purposes of this
article I will accept both their method and their methodology and that it
has had no effect on the accuracy of the dating."

I have read the entire post linked above, which is where the quote comes
from, and which also discusses the report by Jan Heinemier and Hogne
Jungner
as discussed by Suzanne Carlson in her article "Tilting at Windwills: The
Newport Tower." I have also read Hu McCulloch's comments on the dating
issue. I know what the technique used by Junger & Siemonsen was, and the
analysis used by Heinemier and Junger. I also understand McCulloch's
caveats.

Your (linked above) post claims not to doubt that the radiocarbon
methodology used on the Newport Tower is accurate, but calls it
contenious.

Which it is. Nevertheless I think they got their lab work right.

McCulloch raises caveats with the methodology.

Largely the same ones which I originally raised way back about 8 or 9
years ago and which I still believe are problems to be resolved.

Well, which is it? Did they get their lab work right, or are there issues
(caveats)with their methodology?


Carlson doesn't understand the math applied to arrive at the dating.

You don't understand that Carlson didn't understand the calibration
process by means of which a radiocarbon age is turned into a
chronological age.

Isn't that what I posted? She didn't understand the math applied to arrive
at the dating.


My prior posts have stated that there is difficulty in trying to adjust
for
the problems of the reservoir effect, and the use of shell lime, because
such adjustments will require knowledge of the conditions that existed
when
the mortar was created, which may not be the same as the conditions that
exist today, and also it matters where the shells were obtained from and
what percentage of the lime used in the mortar came from shells.

I believe that Junger & Siemonsen and Heinemier and Junger did the best
that
can be done. Beyond trying to adjust the methodology and the mathematical
analsysis for conditions as they did, there is no possible way to know
precisely where the shells used to obtain lime for the mortar in the
Newport
Tower came from, and/or whether some of the lime came from sources other
than shells. There is also no way to know the precise contribution from
the
reservoir effect in the 17th century at the location of Newport, Rhode
Island, against what it is today. Period.

Quite right. But what you persistently fail to realise is that H&J
dealt with the problem by mechanically and chemically separating the
old calcium carbonate from the new. The separation will not have been
perfect but it appears to have been reasonably effective. Its all
described in their paper.

As long as the separation is imperfect, and you don't know the appropriate
localized correction to apply to account for the "old" carbonate, you cannot
have great confidence in the technique. That their calculated radiocarbon
date (date range) agreed with the artifact date range and the absence of any
reports by the English colonists that the Newport Tower was in existence
when they arrived in 1636, leads one to suppose that they got things right,
whether due to good technique or serendipity. It does not mean that their
technique is necessarily applicable as a proven technique, or that it ever
can be.

Here's a 2005 paper that details the problem in radiocarbon dating shell
artifacts:

http://faculty.smu.edu/trick/images/OLD%20SHELL%20JAS.pdf

And here's a 2005 paper on dating lime mortars:

http://www.carbon14.pl/geo/pdf/geo_24/Geo24_15.pdf

The conclusion:
"In the case of lime mortars dating, the real age is the age of binder
because the carbonatious binder takes up the present 14C concentration of
atmospheric CO2 during the hardening process. The problem appears when there
are some unburnt fragments of carbonate rocks or limestone aggregate in the
mortar. In spite of efforts made to eliminate the lime aggregate from the
binder (by freezing, thawing, and separation under the binocular) and
considering the value of d13C, there is still a great discrepancy between
historical evidence and radiocarbon dating for the Roman mortars. The
obtained 14C results for the Dead Sea area mortars were far from historical
premises, although they revealed some regularity. It must be noted, that the
age of the mixture is much more exaggerated then the age obtained for the
binder (Table 1) confirming the enormous influence of aggregate on the
radiocarbon age. The radiocarbon ages of the samples from the medieval
castle in Wleñ confirm the existing architectural-historical data. Further
research will include AMS 14C dating of the binder and charcoal present in
mortars allowing a comparison of the results with those obtained by
historical and radiocarbon dating methods. Separation of fractions from
mortars for dating also seems to be promising (Heinemeier, 1997). The
results of 14C dating show that improvement of the binder-aggregate
separation process is necessary."



The Heinemeier, 1997 reference is:



Heinemeier J., Jungner H., Lindroos A., Ringbom A., von Konow T. and Rud N.,
1997: AMS 14C dating of lime mortar. Nuclear Insttruments and Methods in
Physics Research B 123: 487-495.

You will note that in 2005, the technique of separation of fractions from
mortars is merely deemed to be "promising." You will also note that any
failure to separate the "old carbonate" from the "new," whether physically
as by removing unburnt shell aggragate, or by separating the materials as
per H&J, will skew the results. By how much is determinable only by
reference to a specimen that has a known date, due to the variables that
I've been posting about.


Nothing that you've posted gives any indication that the above problems
that
I have raised can be, or ever will be, overcome other than by adjusting
the
methodology and math in the manner that **the experts** did. So, I will
repeat with some clarifications to facilitate your understanding:

Are you seriously contending that someone could **more accurately**
[accurate] calibrate **for the issues that I raised than Junger &
Siemonsen
did** [those chemicals]? Or that **anyone** [they] can know for a fact
the
source of the shells used in the mortar (if any), and to what extent the
original mortar was mixed using sea shells znd to what extent lime was
obtained from other sources? All of these things will have an effect on
the
percentages of the carbonate and hence the radiocarbon dating.

What you say would be correct if H&J dealt with the problem the way
you seem believe they did. Unfortunately for your criticism, they
didn't do it the way you assume.

You seem to think that I'm unaware of H&J. As noted above, I'm not. I am
also aware that the issues I raised still apply to their technique, since it
isn't clear that a complete separation of the old and new carbonate can be
obtained by their technique.


Since //you// have taken the caveats with their methods (as did
McCulloch),
the burden is on //you (and Hu)// to suggest how to improve the methods
that
have arrived at the currently accepted radiocarbon dating of the Newport
Tower.

Why do you think I started this thread? I was hoping to attract some
informed comments.

You've received them.

(1) There is no way to be confident of radiocarbon dates obtained from old
lime mortar.

(2) Radiocarbon dating of lime mortars generally results in having to
compare the dates to artifacts having known dates, in order to confirm the
radiocarbon date for the mortar.

(3) In the case of the Newport Tower, we have a pretty clear date obtained
from artifacts, and from the failure of European colonist arriving in 1636
to note the existence of a stonework tower on the site of their new colony.


Of course as non-experts in the field (at least, as you posted,
Carlson is a big enough person to admit that she understands little in the
matter of radiocarbon dating), I suspect that you have a row to hoe that
is
way to long for the both of you. Get back to us when you solve the
problems, or at least propose something that would address the problems,
or
when someone else does...

In the meanwhile, I, and others who are rational thinkers, will accept the
result that have been produced that are incontestible:

--- waffle irrelevant to carbon dating snipped ----

And since the "waffle" really gets to the reason why you are prolonging this
discussion for no good reason, I'll restore it:

1) No artifacts datable prior to the 17th century have been found on the
site of the Newport Tower.

2) No reports at all from the original colonists or their immediate progeny
of any "stone tower" existing on the site of the colony when they arrived
there.

3) At least one account (Arnold's) of a stonebuilt windwill.

And I will remind you as I have before in previous incarnations of this
topic:

The issue of the dating of the Newport Tower is really no different than the
typical issues that arise in archaeology. A good case in point is Clovis.
Insofar as evidence existed at a given time, Clovis was an established
hypothesis and the observed data was entirely consistent with it. As time
marched on, people took issue with the hypothesis, and presented data that
was alleged to show problems with the hypothesis. What was perceived as
"entrenchment with Clovis by the old foggys in control," was actually a
matter of requiring that the hypothesis be supported by the new data in a
manner in which it was impossible to argue against the data and the
hypothesis that fit it. As more and more data was presented that could not
be questioned because no rational caveats about the data could be taken,
more and more people accepted that Clovis could no longer be an acceptable
hypothesis.

The same thing applies to dating the Newport Tower:

1) Given the current state of the evidence, and the current state of
objections thereto, no rational thinker would date the Newport Tower earlier
than the 17th century.

2) Might that change someday? Yes.

3) Is there any reason to think that that it ever will? Not at present

4) Is there at least reason at present to be less than 100% certain of the
17th century date? Yes, but because a good scientist should never say
never, only a reason that is so very, very, very small that at present, 1)
and 3) are applicable.

Steve
--
The above posting is neither a legal opinion nor legal advice,
because we do not have an attorney-client relationship, and
should not be construed as either. This posting does not
represent the opinion of my employer, but is merely my personal
view. To reply, delete _spamout_ and replace with the numeral 3




.

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