Re: Radiometric Dating Techniques

Wed, 11 Feb 1998 11:45:25 -0500

Art Chadwick responded to the list, to a note which I sent to him
in E-mail. (I also tried to send a copy to the list, but it was
done separately and I never saw it get through the list.) Here
is the original (sorry if it others have already seen it):

} Date: Tue Feb 10 16:01:07 1998
} Subject: Re: Radiometric Dating Techniques
} I wrote:
} >> The evidence suggests that over the past 10,000 years there have
} >> been fairly rapid but small fluctuations [...]
} Art Chadwick replied:
} > Since there are no trees that have 10,000 continuous rings, I
} > would be willing to bet that there is some tautological analysis
} > involved in that extrapolation.
} The only assumptions in the analyses I've read are that: (1) trees
} growing near each other experienced roughly the same climate (i.e.,
} the pattern of wide and narrow rings corresponding to years with good
} or poor growing conditions can be matched up); and (2) rings grown
} in the same year on different trees would date to approximately the
} same age. These assumptions are certainly reasonable, and alone they
} are sufficient to match up rings between living and recently dead
} trees, and then between those trees and ones which have been dead
} for a longer time.
} > Brown has done some interesting analysis on trends older than 4000
} > years that is revealing.
} Gerald Aardsma (1991, Origins vol. 18 pp. 6-7) points out that
} Brown's compressed carbon-14 scale doesn't really work well. There
} are some long-dead trees with a great number of rings. Due to the
} curve which Brown selects, the "birth" and "death" of these trees
} are "corrected" to almost being the same age. Aardsma references a
} particular example which must have grown 580 rings in 80 years if its
} "corrected" (per Brown) ages are to be used for its first and last
} rings. He also indicates that there are older trees which must have
} produced 20 rings per year if Brown's calculation is accurate.
} Brown pulls a "calibration curve" out of thin air which maps every
} possible "carbon date" to a year which is post-flood. (Actually, in
} one of the papers that Art references -- Origins 17:56-65 -- on
} p. 62 Brown produces two such curves, for different dates for the
} Flood.) In my opinion, Brown has the process exactly backwards.
} The dendrochronological evidence should *tell us* the date of the
} Flood; it shouldn't have to be hammered into an ill-fitting assumed
} one.
} -- Chris

I was hoping Art would comment on the second half.

Art did comment on the first part, saying (in part):
> But suffice to say the chronology before 4000bp is entirely
> dependent on C14 dates of the wood, and is thus tautologous.

I'm going back to dig up the old references, but it will take a

-- Chris