From: sbharris@ix.netcom.com (Steven B. Harris )
Subject: Re: Christian Creation Mythos Question???
Date: 12 Sep 1995
Newsgroups: sci.skeptic

In <434oo6$q8e@gap.cco.caltech.edu> carl@SOL1.GPS.CALTECH.EDU (Carl J
Lydick) writes:

>= 2. Nature, volume 225, March 7, 1970, reported a carbon
>=      14 test was done on organic material contained in the mortar
>=      of an English castle. Although the castle was known to be
>=      787 years old, the carbon 14 date gave an age of 7370 years
>=      old.
>
>So?  Perhaps the organic material came from a peat bog?


    Could be.  Also mortar made with lime (calcium carbonate containing
essentially no C-14) would be off for the very reason the molusc shells
were.  CO2 from coal fires also is absorbed by lime and cement, and
gives bad dates.

    As you note, overlapping tree ring data from living and dead trees
gives us good C-14 dates back for 12,000 years.  In that period, there
is very little error, and the assumptions made (such as the amount of
C-14 being the same in the atmosphere everywhere at any one time) are
very modest.  You don't even need to assume anything about decay rates
during this period.

                                        Steve Harris, M.D.