From: Glenn Morton (glenn.morton@btinternet.com)
Date: Sun Jan 12 2003 - 08:30:58 EST
Allen wrote
>-----Original Message-----
>From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu]On
>Behalf Of allenroy
>Sent: Wednesday, January 08, 2003 5:47 PM
>To: asa@calvin.edu
>Subject: Some Comments on Radiometric dating.
>
>
>
>Its been a little slow on the ASAnet so I thought I'd throw this out. :)
>
>I have 3 points to make.
>
>1: There is a distinction to be understood between computing apparent
>ages according to certain assumptions from scientific quantification of
>an assortment of isotopes in rock, and the acceptance of those dates as
>valid for the rock involved.
Allen, the very basis of dating is stratigraphy which involves the
geometrical relationships between the various rock layers. Veins which
cross-cut other rocks are emplaced after the rocks were in place. With
sedimentary rocks, lacking geometrical evidence of overthrusting, the
topmost rock is the youngest. Radioactivity can go wrong and does. If the
dates violate the very laws of deposition, the laws of depositon take
precedence. It is logical to do it that way. I might make a note that the
reason you know of bad dates is because the scientists do publish bad dates,
contrary to many claims by the YECs.
(Actually, the process of measuring
>isotopes has evolved to the level of technology rather than scientific
>experiment. Very few today conduct scientific experiments to measure
>isotopes, rather, rock samples are submitted to labs who have the
>technology to process the rock to measure contained isotopes.) I don't
>know of any Creationary scientist who quarrels over the methodology,
>accuracy and precision with which isotopes are measured and ages
>computed. Most have, however, focused on the validity of assumptions of
>radiometric dating.
If they accept the validity of the measurements, then I would like to see a
YEC explanation for why the ratios of various isotopes vary systematically
with the stratigraphic position of the rock. Even when a young-earther goes
through the literature looking for bad dates, one can still see this
relationship. Isotope percentages vary according to the stratigraphic
relations of the rocks.
John Woodmorappe (1979) went through the scientific literature looking
for radioactive dates which are 20% too old or too young. He specifically
excluded from his search any date which matched the expected age. This
type of selective editing is exactly what Young earth Creationists charge
the Evolutionists with. Woodmorappe says
"An objective comparison between the number of fitting vs. the
number of anomalous dates in the Phanerozoic is hindered (if not prevented)
by the fact that anomalous dates frequently (or usually) are not reported
in scientific journals."; (Woodmorappe 1979, p. 113)
Thus while he criticizes the old-earther for selectively publishing
radioactive dates, he does the very same thing by only publishing bad dates.
This seriously hurts his credibility. In his article he listed these bad
dates but did not plot them. If he had, he would have seen something
remarkable.
Above the 350 dates are plotted . A perfect dating result should appear
on the line. Note that there are more dates under the line than above the
line. If radioactivity is producing dates which are too old, you would
expect that there would be more dates above the line than below the line.
What this proves is that if a radioactive date is wrong it is far more
likely to be too young than too old! Young earth creationists need the
dates to be too old if their viewpoint is correct.
http://www.glenn.morton.btinternet.co.uk/radchart.gif
What is your explanation? Chemically, why is this?
>I live not far from Grand Canyon, and in fact, I conduct Creationary
>Cataclysmic tours there for those interested in hearing the latest
>models concerning Noah's Flood. (see
>http://www.tagnet.org/anotherviewpoint ) As most every one knows,
>radiometric dating is done primarily on igneous rock. Within Grand
>Canyon are several outcrops of volcanic rock, two of which I'd like to
>talk about -- familiar to many who know of Grand Canyon. They are the
>Cardenas Basalts of the Grand Canyon Supergroup at the bottom of Grand
>Canyon and the Uinkaret plateau lava flows. These outcrops are of
>interest because the Cardenas Basalts represent some of the oldest rocks
>in Grand Canyon, existing below all the horizontal layers which make
>Grand Canyon so famous. On the other hand, the Uinkaret Plateau lava
>flows extruded on top of the plateaus above the canyon, some of which
>also flowed down inside Grand Canyon. Everyone agrees that the Uinkaret
>lava flows must be younger than the formation of Grand Canyon (less than
>1 million years) and that Grand Canyon must be younger than the Cardenas
>basalts. Ergo, the Uinkaret lava must be younger than the Cardenas basalts.
>
>I think that most everyone also knows that when Rb/Sr radioisotope
>measurements were made of these rocks, contrary to what was expected,
>the Uinkaret lava flows actually measure and compute to be OLDER (~1.3
>Billion years old) than the Cardenas Basalts (~1.0 Billion years old).
>This is a conundrum to any geologist -- Creationist or Evolutionist. All
>arguments about assumptions and justifications aside, it still remains a
>fact that EVERYONE discards and rejects the Rb/Sr data for the Uinkaret
>lava flows. Although the methodology and technological processes were
>faithfully and precisely followed on rock samples from both sources, the
>dating for the Uinkaret is rejected while dates for the Cardenas are
>accepted.
>
>This comes to my point. Just because the process of radiometric dating
>is done with great precision and great care, that does not automatically
>mean that the results are going to be accepted as valid. In the many
>geological papers that I've read where radiometric samples have been
>processed, there is usually a "discussion" about whether to accept or
>reject the ages so acquired. That choice comes about through factors
>other than the accuracy of the radiometric process. In the case of the
>Uinkaret/Cardenas igneous rock, non-scientifically acquired data
>actually takes precedence over the scientifically (technologically?)
>acquired radiometric data. It is strictly observation and logic (not
>scientific experiment) that shows that the Uinkaret must be younger than
>the Cardenas. This fact outweighs the scientific data acquired through
>the radiometric dating process.
Why is it Allen, that when YECs like you claim great successes, you never,
ever seem to acknowledge that someone has criticized the work you are
presenting? Why is it that YECs only ever present one side of the question.
You should be aware that Chris Stassen has written a critique of the methods
Austin used to date the uppermost lavas and documented how Austin rigged the
results. Isochron methods apply to a single rock, or mineral in which
several isotopic ratios are determined for that SINGLE mineral. Austin, it
seems, used 4 different rocks from 4 different lava flows. This is not the
correct way to do isochron dating. Stassen says:
"Before the Grand Canyon Dating Project began, in his 1988 Impact article,
Austin admitted in print that the selected lava flows fell into two
different stratigraphic stages. That is, the very information which he used
to select the flows, also clearly indicates that they did not all occur at
the same time. In his subsequent book (Grand Canyon: Monument to
Catastrophe), Austin indicated that his five data points came from four
different lava flows plus an extracted "phenocryst" (large mineral which
likely formed in the magma chamber and was not molten in the lava flow). We
had known from the Impact articles that Austin's samples were not all
cogenetic; years later we find out by his own admission that no two of them
are so. " http://www.talkorigins.org/faqs/icr-science.html#refaus88
>
>So, Point 1 is: The acceptance or rejection of radiometrically acquired
>ages for rock depends upon factors other than the science/technology of
>radiometric dating. (The Uinkaret/Cardenas system is symptomatic of the
>entire radiometric dating scheme).
Point 1 through 3 should be the fact that YECs misrepresent things.
>
glenn
see http://www.glenn.morton.btinternet.co.uk/dmd.htm
for lots of creation/evolution information
anthropology/geology/paleontology/theology\
personal stories of struggle
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