Re: virus: Mother-Daughter Dating
Tue, 18 Feb 1997 11:13:38 -0600 (CST)

On Fri, 14 Feb 1997, Reed Konsler wrote:

> Zamboni wrote:
> >The assumption I balk at is this: the starting level of a
> >mother-daughter
> >based dating method is ALWAYS 100% mother, 0% daughter.
> Richard wrote:
> >I agree this is true in most cases. However, there have been
> >well-documented cases in which experimenters have dated the DAUGHTER
> >first, only to progress to dating the mother some months later. These
> >cases, however, almost always involve some intentionality on the part of
> >the mother and so may perhaps be discounted.
> Sad to say this is yet another example of antiquated cutural practices standing
> in the way of the advancement of science. In order to be completely rigourous
> it would be necessary for the researchers to engage in double-blind dating
> with a randomized sample of mothers and daughters. I've heard of some
> attempts to reduce this to practice, but not in any repudable publications.

The above context has nothing to do with geology.

An example of appropriate context is this:

We have a radionucleide chain, starting with U235, and ending up at Pb___
[point: this isotope is stable. Uranium decays to lead, with
intermediate chains of neglibible half-life.]

This, in principle, provides a suitable clock for assigning [maximum, but
the literature NEVER mentions this!] ages to appropriate minerals.

You measure the current ratio of U235 to Pb___, and then compute the time
that it would take for a ratio of 1:0 to decay to the current one. The
hard part of the entire exercise is the measurements; even a College
Algebra student [B or higher grade, please] can do the time computation.

There are several others. C14 does *not* qualifer, because the
starting level can be estimated to high precision by other means.

/ Towards the conversion of data into information....
/ Kenneth Boyd