From: allenroy (allenroy@peoplepc.com)
Date: Thu Oct 02 2003 - 19:50:48 EDT
Michael Roberts wrote:
> >Take a recent work by Andy Macintosh "Genesis for Today " published in
> Britain 2001.- the only country in the world in which the leader of the
> government endorses the teaching of YECreationism in state schools
> >Misstatements
> [snip]
> >He then cites the Cardenas basalts of the Grand Canyon as 1by. Surtsey etc.
"1100 m.y.a. for the Cardenas Lava using the Rb-Sr method. The K-Ar method has
produced Cardenas ages that are considerably youngar than 1100 m.y.a. Ford and
other presented a single K-Ar age of 845+/- 20 m.y.a. ...Mckee and Noble
obtained ages of 810 +/-20, 790+/-20 m.y.a. ..."
Hendrics and Stevenson, 1990, Grand Canyon Supergroup: Unkar Group, in Beus and
Morales eds., 1990, Grand Canyon Geology, pg. 35
So, what were you objecting to? The 1 billion years for the Cardenas by Rb-Sr
or for no 1 billion years through the K-Ar method?
> >You will find some critique on the talk origins site , Wiens paper on the ASA
> site etc etc etc .
Wiens' paper is sophomoric if not 6th grade level and does not even deal with
the issues raised by YEC critics.
Some thoughts on isotopic dating
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 from rock, and the acceptance of those dates as valid for the rock
involved. Even McDougal and Harrison (1988, pg.11) note this: "As with all
isotopic dating methods, there are a number of assumptions that must be
fulfilled for a K-Ar age to relate to events in the geological history of the
region being studied." (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 which 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
isometric dating. I would like to make another point.
As most every one knows, Isometric dating is done largely 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 into Grand Canyon. Everyone agrees that
the Uinkaret lava flows must be younger than the formation of Grand Canyon (less
than 5 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 (~1.1 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 computed ages for the Uinkaret lava flows as applying to when they
flowed and crystallized. 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 isometric 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 many geological papers where
isometric 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 isometric process. In the case of
the Uinkaret/Cardenas igneous rock, non-scientifically acquired data takes
precedence over the scientifically (technologically?) acquired isometric data.
It is strictly observation and logic concerning the law of superposition that
shows that the Uinkaret must be younger than the Cardenas. This fact outweighs
the scientific data acquired through the isometric dating process.
So, Point 1 is: The acceptance or rejection of isometrically acquired ages for
rock depends upon factors other than the science/technology of isometric dating.
(The Uinkaret/Cardenas system is symptomatic of the entire isometric dating
scheme).
2: The second point concerns scientific objectivity. We are given the impression
that:
1. science is objective;
2. isometric dating is science; therefore
3. dating of rock units using isometric methodology is objective
science.
However, as we have just seen, the scientific objectivity of isometric dating is
only applicable through the methodology of sampling, processing and computing of
a isometric age. After that point, a isometric age may be countermanded by other
important information and data. The point I want to make now is that at the very
moment that an isometric age is rejected (or even accepted) based on other data,
the isometric dating method immediately becomes subject to that other
information. Thus, no matter how precise the isometric process has been, the
results are still handled subjectively. In the case of the Uinkaret, the
computed ages are rejected because it is impossible for them to be correct. In
the case of the Cardenas, the computed ages are accepted because they agree with
what is expected.
So, Point 2 is: The dating process of rock units is subjective even when
isometric dates are available. The isometric dates may be accepted or rejected
depending upon other information.
3: I'll just state this point right off the bat;
1. If any rock unit is believed to be young, then any old isometric
age is rejected, not as inaccurate, but as irrelevant. OR,
2. A rock unit must first be thought to be of a certain age before
such an age will be applied to it. OR,
3. A rock unit must first be thought to be old before an old age is
applied to it.
The truth of the first statement is borne out by the lava flows of the Uinkaret.
Everybody, but everybody, but EVERYBODY believes that the Uinkaret basalts must
be young, therefore the 1.3 billion year isometrically computed age is not the
result of inaccuracy in the radio isotopic dating method, but rather it is
completely irrelevant.
The truth of the second statement is borne out by the K-Ar computed ages of the
Uinkaret basalts ranging from 10,000 years to 117 million years. Everyone knows
that the Uinkaret basalts must be younger than the age of Grand Canyon (less
than 5 million years) so the age of the Uinkaret appears relatively confirmed by
the K-Ar isometric computed ages (even though the computed ages vary by more
than 2 magnitudes).
The truth of the third statement is borne out by the acceptance of the computed
old ages from Rb-Sr (~1 Billion years) and K-Ar (~800 Million years) for the
Cardenas basalts which had to be in place long before the Phanerozoic rocks were
deposited through which, even later, Grand Canyon was carved. Very few have ever
doubted the computed ages applied to the Cardenas, nor even considered looking
for younger dates.
Summary:
1. The acceptance or rejection of isometrically acquired ages for rock
depends upon factors other than the science/technology of isometric
dating.
2. The dating process of rock units is subjective even when isometric
dates are available.
3. If any rock unit is believed or known to be young, then any old
isometric age is rejected, not as inaccurate, but as irrelevant.
So where does this bring us?
I, as a Creationary Cataclysmist, consider that all igneous rock units found
within the Phanerozoic (the geologic record of sedimentary rock units containing
fossil and thus must be post sin) are probably mostly emplaced during or after
the flood cataclysm. Therefore, based on chronological evidence in the Bible,
the Phanerozoic and included igneous formations are approximately 4000 years
old. Since I believe that these igneous rocks must be very young, then all
isometrically acquired and computed old ages are not just inaccurate
measurements and computations, but rather, they are completely irrelevant to the
age of the rock.
Within the Biblically based paradigm of Creationary Cataclysmism, old
isometrically computed ages for igneous rock contained within the Phanerozoic
record have no meaning or reality. (please note, I am not here discussing the
age of the Universe nor of a pre-creation week planetoid that likely existed in
a void state.) All such computed old ages can be safely ignored as totally
irrelevant and they have no bearing at all in preparing flood models.
-----
*Ian McDougal and T. Mark Harrison, 1998 "Geochronology and Thermochronology by
the 40Ar/39Ar Method" pg.11
Allen
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