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From: bob@islenet.UUCP (Bob Cunningham)
Newsgroups: net.origins
Subject: Re: The Scientific Case for Creation: (Part 32)
Message-ID: <1409@islenet.UUCP>
Date: Sat, 27-Jul-85 19:47:27 EDT
Article-I.D.: islenet.1409
Posted: Sat Jul 27 19:47:27 1985
Date-Received: Wed, 31-Jul-85 20:04:42 EDT
References: <386@iham1.UUCP> <62@uw-june> <517@ihu1m.UUCP> <86@uw-june>
Organization: Hawaii Institute of Geophysics
Lines: 32

> >> [discussion of the accuracy of C-14 dating]
> 
> >[Yosi Hoshen]
> >The creationist are trying to confuse the issues.  The half life of
> >carbon 14 is few thousand years, therefore, it is not useful for
> >dating objects on a prehistorical scale.
> 
> Not true.  If I remember correctly, current techniques allow carbon dating
> to be used on objects as old as 500,000 years...

To set the record straight, the average C14 atom takes 8200 years to decay.
As time goes on, there are fewer C14 atoms in a particular sample to decay,
and the resulting "half life" is thus 5700 years.  At an age of about
40,000 years, less than 1% of the original C14 remains.  Since we're
talking about an original ratio of about one C14 atom per 10^12 total C
atoms, the drop by two more orders of magnitude makes measurement even more
difficult.  It's also reasonable to consider that Carbon exchange by
diffusion can add some uncertainty.  In current practice, a date beyond
60,000 years would be difficult to believe.

C14 dating has been cross-correlated with historical events, tree ring
counts, coral growth ring counts, pollen, and K-Ar dating (charcoal from
burned trees in lava flows).  While there may have been some small
deviations in the C14/totalC ratio in the past atmosphere & ocean, there
certainly was a major increase following the atmospheric nuclear tests
of the 1950's.  This is one (of several) clearly distinguishable radioactive
tracers that can be used to accurately determine sedimentation rates all
over the world during the past few decades.
-- 
Bob Cunningham  {dual|vortex|ihnp4}!islenet!bob
Hawaii Institute of Geophysics Computing Facilities
Honolulu, Hawaii