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From: lief@hpfcla.UUCP
Newsgroups: net.origins
Subject: Re: Re: Orphaned Response
Message-ID: <14600038@hpfcrs.UUCP>
Date: Mon, 12-Aug-85 17:18:00 EDT
Article-I.D.: hpfcrs.14600038
Posted: Mon Aug 12 17:18:00 1985
Date-Received: Sun, 25-Aug-85 05:03:01 EDT
References: <14600027@hpfcrs.UUCP>
Organization: 12 Aug 85 15:18:00 MDT
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In article <14600030@hpfcrs.UUCP> lief@hpfcla.UUCP (lief) writes:
>>
>>If an organism (fossil) is found in rock strata, and one wishes to get the
>>age of the organism, what are the steps he goes through to arrive at a figure?
>>
Sarima (Stanley Friesen) replied:
>
>	This shows little understanding of the actual conditions under
>which fossils are found. Material incorporated into sediment while it
>is still unconsolidated shows a quite different relationship to the
>resulting rock stratum than would material inserted *after* the
>sediment is consolidated. If you had ever actually watched fossils
>extracted from sedimentary rock it would be obvious that the fossils
>were incorporated in the sediment at the time of deposition, *not*
>at a later time. Since the age of a sedimentary stratum is the time
>since deposition, *not* the age of the source material, the kind of
>error you are talking about simply can not occur.
>	Of course if you *were* talking about being buried in new
>sediment derived from billion year old source material you are again
>totally unfamiliar with dating techniques. This factor is *routinely*
>taken into account. That is why so few actuallly fossiliferous strata
>can actually be dated *directly*, radiometric dating must be applied
>to untransported material(such as volcanic rock)  to generate valid
>results. The age of the sedimentary strata must then be estimated by
>interpolation.
>-- 
     It's true that I am not familiar with dating techniques as such.  I
had always assumed that it was the source material itself that was being
dated rather than the time of deposition.

     Obviously, radiometric techniques are not used directly for dating
the time of deposition, right?  If interpolation is used, then that means
that there exists at least 2 fixed known points to be used as reference.
What is usually used for these reference points?  And how can one interpolate
unless he assumes uniformation?

Lief Sorensen
HP Fort Collins, CO
Uucp ...!hpfcla!lief