>> If the basalts come from different primary sources, the isochrons
>> are indeed suspect. I don't know enough about Austin's work to
>> confirm or challenge Dalrymple's assertion - but would be very
>> interested to hear how he justifies the words "demonstrably not
>> cogenetic".
I will send the files I got this information from to David. Anyone else
who wants a copy, mail me.
> Jim Foley said:
> Using non-cogenetic rocks should cause data points not to fit on a line.
> But Austin apparently was able to get a line *by throwing away points that
> did not fit on it*. That is also a violation of the way isochron dating
> should be done.
>> Again, this seems to be an important assertion and I would like
>> to know more. If there's no further feedback on this, I write to
>> Steve Austin for his comments.
I'll note that Dalrymple did not flat-out assert that Austin was
discarding data points; he *thought* that was what was happening, and
gave some justification for this, but said that Austin's data was not
complete enough to properly evaluate his work. He seemed much surer
about the problem of using non-cogenetic rocks though; I think this was
verifiable by examining Austin's sources.
David, if you are a geologist, perhaps you will be good enough to give
us your evaluation of the material I am sending you.
-- Jim Foley Symbios Logic, Fort CollinsJim.Foley@symbios.com (303) 223-5100 x9765* 1st 1.11 #4955 * "I am Homer of Borg! Prepare to be...OOooooo! Donuts!!!"