>>> "Charles Carrigan" <CCarriga@olivet.edu> 04/28/06 12:13 PM >>>writes:
I have no idea who Baskaran is, but stating that "geologists are reluctant
to be certain of a date that is not verified by multiple means of dating" is
not the best way of putting it. I don't know any geochronologists who think
this way - e.g., "ok, i've dated this rock once, now i've got to date it
again by another method before I can have confidence in the data".
Geologists rely on numerous dating methods, but one does not have to date a
geologic event by multiple means in order to be certain of it. Rather,
different methods have different levels of reliability, and the method
chosen is dependent on what kinds of materials and questions are being
investigated. Further, some skill is required to do this kind of work, and
quite frankly, some geochronologists are more skilled at different methods
than others. Even more frankness, some geochronologists are really bad,
using techniques that should simply not be used (Pb-Pb evaporation on zircon
from high-grade terranes comes to mind). Yet this method is still sometimes
employed and published in the literature (and then subsequently challenged
later by someone else!). Other geochronologists are excellent at what they
do, and if they publish a date, you can be sure it is pretty reliable.
Often when a rock is dated that has been dated previously, the reason is
because either new methods are available that are more reliable than the
old, or the new investigators simply doubt the data or methods employed by
previous workers for some reason.
Ted comments:
Having talked to Dr Baskaran, I can say that his speciality is
geochronology, specifically various radioactive methods, whose general
reliability he fully endorses. He is also a Christian, and I left with him
a copy of PSCF and information about the ASA. He's heard about us before
and thought of joining, perhaps I pushed him over the top and he'll sign
up....
Ted
Received on Sat Apr 29 09:31:23 2006
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