Re: Isotope question

Steven Fawl (fawl@nvc.cc.ca.us)
Wed, 8 May 96 09:04:05 -0700

At 10:26 PM 5/7/96 -0400, you wrote:
>Greetings,
> I've got a quick question that perhaps can be quickly answered.
>I recently saw a presentation by a YEC advocate which showed a piece
>of lava from an 1801 eruption which was (allegedly) dated via K-Ar
>dating as approximately 2.1 billion years old. I have a 4th edition
>(1982) copy of Stokes' _Essentials of Earth History_ which indicates
>that K-Ar has a half life of 1.3 BY and that it is applicable "to many
>common minerals, such as ... certain fine-grained volcanic rocks."
> Obviously, it seems that it would be an appropriate test that, for
>some reason, seems to have gone drastically wrong. Can anyone suggest
>some interesting details which might have been omitted? (Obviously,
>if I'm looking things up in a lower division text, this isn't really
>my bailiwick!) Thanks,

Yes. The 1801 eruption is a well known YEC apologetic to show how K/Ar
dating is wrong. I once attended a meeting at a local church where John
Morris used this data to try to show how K/Ar dating was wrong. As it so
happened I had a copy of the article with me and I gave it to John to read.
After reading the article he said that he would no longer use the 1801
eruption as an example of why K/Ar dating was wrong.

The article shows that there is a relationship between water depth and Argon
outgassing from volcanic rock. The study showed that lava deposited in deep
water (as occured in the Hawaii 1801 eruption) could not release trapped
Argon gas and would therefore produce K/Ar age dates that were too old. It
was interesting to see the data. The authors took samples from various
depths and dated them and it was easy to see that the rocks found near the
surface dated young (essentially zero age) and as you moved into deeper
water those rocks produced progressively older ages for the rock. The
bottom line in the article was that the researchers warned against taking
volcanic rock samples at depth and dating them using K/Ar dating since it
could easily be shown that these rocks gave erroneous dates. I do not have
the data, nor the paper with me, but I believe that this was the gist of the
paper.

What John Morris saw in the paper that dissuaded him of it's use was that
the not all of the data was being reported by the YEC's (by him either, at
the time) and therefore was not representative of the papers intent. It was
clear to him after reading the paper that it had been misrepresented and he
told me personally that he would not use it again.

Steve