Re: Some Comments on Radiometric dating

From: allenroy (
Date: Wed Jan 29 2003 - 17:53:01 EST

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    Glenn Morton wrote:

    >Allen wrote:
    >>**[allen]Yes, Precisely; that is the heart of my thesis. Point 2 is
    >>"The dating process of rock units is subjective even when radiometric
    >>dates are available."
    >No, Allen, it is not subjective, when seeing undisturbed strata, to know
    >that the lower layer is the older. This is because you can't deposit
    >sediment underneath the ocean bottom or land surface. You are using
    >'subjective' in a funny way.
    ***I have been puzzling over your response here, because it appears to
    me that you have somehow not understood what I was saying. The only
    thing that we can get from the law of superposition is the 'relative'
    time relationship of the formations. What I have been talking about is
    that the application of isotopically acquired 'dates' to specific rock
    units is subject to the law of superposition. So my "dating process of
    rock units" in the above sentence refers to the application of a date or
    era to a rock unit. And when that date is acquired through isotopic
    means, no matter how "precise" the isotopic measurements were and no
    matter how accurately the computations were, the date is still put
    subject to the law of superposition. Its really that simple.

    >>Meaning subject to the laws of stratigraphy.
    >>And, being "subject to" means that isotopic dates are rejected or
    >>accepted depending upon other factors than the accuracy of the isotopic
    >>dating methods. (Point 1)
    >So? Big deal. If you see something wrong are you going to continue to
    >believe the wrong thing so that you won't have to reject something? How
    >stupid do you want the chronologist to be?
    ***I made this obvious point because it is often skimmed over, but it
    has very important consequences. And that is, like I said above, the
    accuracy or isotopic measurements nor the accuracy of computations is as
    important as the law of superposition.

    >Also, why do you expect radiometric dating to have god-like perfection or
    >else it must be totally rejected as useless? That is like saying if your
    >car doesn't start 100% of the time, it isn't of value to you. Everything in
    >this world is fallible, yet the YECs always seem to expect science and
    >scientific methods to live up to absolute perfection in order for them to
    >then claim, "nanny-nanny-boo-boo it doesn't work at all'. Which of course is
    >absolutely laughable. Or would be if people didn't believe this ridiculous
    ***A theory can be proven wrong with just one falsification. In fact, a
    theory is not really a theory unless it can possibly be falsified. If
    and when a theory is falsified it must then be modified or rejected.
      The method of Isotopic dating has been falsified many times, but it has
    yet to be modified or rejected. It still starts with the concept that
    the elements and isotopes do not migrate in or out of the rock. This
    has been falsified, yet the assumptions still remain the same. Rather,
    the assumptions should be modified to say that the elements and isotopes
    do migrate in and out of the rock. Then the quantities of such
    migration should be measured or estimated. And, then and only then,
    dates computed. But it doesn't work that way. First dates are computed
    and then (and only if the dates don't fit) the quantities of migration
    are estimated (usually so that the "correct dates" are acquired). That
    is not science.

    ***One can understand that error can occur within a theory. And one can
    understand the reluctance to abandoned or modify a theory unless there
    is much evidence to do so. But that is precisely where isotopic dating
    is at.

    >>And the fact that isotopic dates for the
    >>Uinkaret are rejected because they do not stratigraphically fit shows
    >>Point 3, "If any rock unit is believed to be young, then any old
    >>radiometric age is rejected, not as inaccurate, but as irrelevant to the
    >>age of the rock."
    >You are not answering the objection to Austin's 'dates' (and I put that in
    >quotes on purpose) because Austin used isochron values from different rocks
    >which violates the method. Here is something I wrote back in 1995. It shows
    >how erroneous Austin's methods are. ...[section snipped] ... Here is what
    >George D. Garland says of the discovery of the Isochron method,
    >"This difficulty of correcting for common strontium was solved by Compstons
    >Jeffrey and Riley (1960), who pointed out that isotope ratios could be
    >determined for several constituent minerals of the same rock."
    >[note that this is not several rocks as Austin did--grm 2003]
    Rb/Sr from the Uinkaret (Austin samples):
    4 'whole rock" samples give ages of 1.32, 1.39, 1.38 and 1.34 billion years.
    1 'constituent mineral' sample gave an age of 1.27 billion years.
    An Isochron using these 5 samples gives 1.34 billion years.
    There is huge concordance here!

    Rb/Sr from the Cardenas Basalts (McKee and Noble samples)
    6 "whole rock' samples give ages of 1.06, 0.98, 1.09, 1.09, 1.07, and
    1.10 billion years
    An Isochron using these 6 samples gives 1.07 billion years.
    There is huge concordance here!

    ***So, why are the ages for the Uinkaret rejected while the exact same
    methods done on the Cardenas are accepted?

    ***There has never been "constituent mineral" dating done on the
    Cardenas, yet the computed dates there are accepted.

    ***Because there has not been an isochron computed solely from
    "constituent minerals' for the Uinkaret the computed ages are rejected.

    ***Do you sense the inconsistency here?? Its back to "head's I win,
    tails you loose."

    >>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.
    >>**I can do no better than Woodmorappe, 1999, "C. Stratigraphic Trends in
    >>Isotopic Dates," in Chapter 3 "Bogus Arguments for the Overall Validity
    >>of Isotopic Dating methods." in 'The Mythology of Modern Dating
    >>Methods," pages 18-23
    >I don't have easy access to YEC books over here. What does he say? Or is
    >this request going to be classed a red herring or irrelevancy also?
    *** If you are confused about logical fallacies I can give you a URL
    that explains them clearly.

    C. "Stratigraphic Trends" in Isotopic Dates

    Myth: Since results of dating methods typically fall in he millions of
    billions of years, the correct ages of rocks must be within this general

    Reality Check: First, let us take this argument to its reductio ad
    absurdum. Let us do this by considering historical lavas. We can find
    some of them that give an apparent K-Ar age in the few tens of millions
    of years. Then we compare this with some historic lavas that have
    fictitious Rb-Sr isochron ages in the few tens of millions of years.
      Or, we can use the simulated Rb-Sr isochron of twenty-seven million
    years, derived from Rb-Sr ratios, on modern lavas, (described by Lutz
    and Srogi 1986, p. 68). Following the logic of those who assert the
    general correctness of "comparable ages," we could argue that both
    dating methods (K-Ar and Rb-Sr in this case) corroborate the "fact" that
    modern lavas are actually a few tens of millions of year old!

    The central premise undergirding the belief in the over all validity of
    the multimillion/multibillion year ages, as it turns out, it he
    assumptions of the validity of the dating methods themselves. What if
    this assumption was not believed? In such a situation, these isotopic
    systems would be understood to be little more than geochemical
    phenomena, and certainly not gochronometers. There would then be no
    reason to take seriously the inferred multimillion to multibillion year
    ranges seemingly indicated by these methods. In particular, once we
    understand that, during the Flood, colossal amounts of magma were
    generated, and much argon was trapped in the magma (e.g. Austin 1996,
    Snelling 1998), there is no reason to be surprised by the millions and
    billions of years apparently indicated by the K-Ar method. Likewise,
    once we understand the implications of mixing lines, and similar
    geochemical phenomena, there is no need to take seriously the millions
    and billions of years apparently indicated by the Rb-Sr method. An
    analogous line of reasoning holds for the other so-called dating methods.

    Myth: Even when discordant (by one or more methods), results are still
    comparable with each other; therefore isotopic dating results must be
    generally correct.

    Reality Check: While it is true that many data sets of such results are
    frequently comparable, there are also many instances when they are
    strongly discordant. For instance, a suite of lamprophyre dykes in the
    Canadian Shield has yielded a wide range of results ranging from 300
    million years all the way to 1.7 billion years (Queen et al. 1996, p.
    958). In other situation, the isotopic dates disagree by an order of
    magnitude or more. The latter include cases of "rejuvenated"
    Precambrian basement, examples of which I have provided in the earlier
    paper (Woodmorappe, 1979, 1993). A recent example of this is provided
    by the Natal Metamorphic Provinces (Jacobs and Thomas 1996), where the
    dates "smear" from 1.1 billion years to approximately 180 million years
    age (op cite, pp. 971-972), which is nearly an entire order of magnitude
    of difference. The older results are believed to approximate the age of
    the origin of the lithologyies, and the younger results are from periods
    of reheating (that is, "rejuvenation," and time since the rock
    temperatures supposedly last fell below the closure temperature of a
    particular isotopic system). In another instance, a comparable range of
    "dates" which span an order of magnitude, derived from
    geographically-coherent lava flows, was blamed on "excess argon"
    (Seidemann 1988). In this case, it was the Mesozoic dates which were
    accepted are reliable. Obviously, such reasoning is convincing only to
    those who already believe the validity of these isotopic dating methods,
    as it begs the question about the validity of these isotopic dating
    methods in the first place.

    When considering uniformitarian geology in general and isotopic dating
    in particular, we must watch for "cover words." These include "collage
    of terranes," which serves as a cover for widely-contradictory dating
    results from adjacent suites of lithologies:

         "In summary, the Rae "cration" appears to be a relatively complex
         amalgamation of Archaen and Proterozic material of a wide range of
         ages. A recent model for the evolution of the area has suggested
         that the ''cration" represents a tectonically accreted collage of
         terranes, overthrust westward unto the superior craton during
         east-west convergence between the Main and Superior cratons (Scott
         1998, p. 95)."

    In other instances this procedure of invoking some form of accreted
    terranes is not even self-consistent and is, as usual, blamed on
    geologic complexity:

         "Uncertainty over which craton a given zircon age 'belongs to'
         arises from two sources; disagreement over where the boundaries
         between 'true' parts of cratons and (presumes) microcontinents
         should be drawn; and the realization that unlike other parts of the
         world, cratons in Eurasia underwent substantial growth and
         development during the Phanerozoic (Hacker et al. 1998, p. 223)

    Examples of 'rejuvenated' Precambrian igneous bodies, and their wide
    range of conflicting dates, could be multiplied ad infinitum. But even
    the results of one method can spread over a considerable range of
      values. For instance, a series of dykes intrude Proterozoic 'basement.'
      The hornblende gives K-Ar results all of which are in the proterozoic
    range. By contrast, the K-Ar biotite results spread over a range that
    exceeds an order of magnitude in value: 76 million all the way to 1640
    million years (Rex et al. 1993, p. 273). At other locations, the
    discordances can be even greater--approaching three orders of magnitude.
      Thus, some Precambrian 'basement' rock, located in the western Canada
    sedimentary basin, are believed to be 2.0 billion years old, yet give FT
    dates as young as 2.2 million years old (Willett et al. 1997, p. 977).

    Discordances, measured in orders of magnitude, between results of a
    single dating method and/or different dating methods, can also be found
    in sequences of ostensibly young rocks. For instance, pooled K-Ar and
    FT ages from the volcanics of the Taiwan-Luzon arc range widely from
    0.02 to 49.9 million years (Yang et al. 1995). this is over three
    orders of magnitude, and this huge range is blamed on a combination of
    xenocrystic contamination, excess Ar, and alteration.

    Orogenic belts comprise another source of widely divergent isotopic
    dates from relatively small geographic areas. One might intuitively
    suppose that belts of plutons of whatever age (Paleozoic, Mesozoic, and
    Cenozoic) should trend more-or-less randomly on earth, intersecting each
    other sporadically and randomly, but his is far from the case. Seldom
    are areas of Precambrian crust transversely cut by Phanerozoic orogens
    (Sykes 1978). And orogenic belts of whatever 'age,' with their
    associated plutons, tend to occur in the same general areas on earth
    (Beloussov 1990, Ryan and Deway 1997). Thus, geographic areas
    containing Meso-Cenozoic plutons often, if not usually, also contain
    Paleozoic (and older) plutons. This is explained, by advocated of plate
    tectonics, as a consequence of suture zones being weak areas of crust
    that tend to tear apart in the same are over and over again in geologic

    One implication of the phenomenon is the fact that an investigator often
    obtains a large diversity of isotopic dates from a series of
    geographically-proximate plutons. To someone without a prior belief in
    the great antiquity of the earth, talk of repeatedly-rejuvenated crust
    is vacuous. Rather, the evidence point to a highly-contradictory
    datasets of isotopic dates from closely-clustered plutons. A
    uniformitarian can argue about a complex geologic history all he wants.
    and spin just-so stories about repeated episodes of igneous intrusions
    and partial 'rejuvenation' of older plutons in the area. However, the
    empirical evidence at hand contradicts his claim that results of
    different dating methods ar generally comparable. Instead, there often
    exists a string f discordant results, by many different dating methods,
    and coming from plutons which are not geographically distant from each
    other. Let us consider as an example, the Leadville quadrangle in
    Colorado (Wallace 1995). Closely-neighboring granitic bodies yield
    results which span nearly two order of magnitude--from about 20 million
    years to near 2.0 billion years. The Cross Creek Granite itself yields
    results ranging from 1.7 billion years to 29 million years (Wallace
    1995, p. 40).

    Finally, if one goes ahead and reckons discrepantly-old Rb-Sr and Sm-Nd
    isochrons as 'ages,' this creates a large dataset of situation where
    results of different dating methods disagree by an order of magnitude or
    more. for instance, plutons in the Yukon Territory (Canada) have
    yielded K-Ar and Rb-Sr 'cooling dna crystallization' ages of 60-100 Ma
    range, but also 'inherited Rb-Sr isochrons of up to 1380 Ma (Pigage and
    Anderson 1985). This is also true of presumably-young rocks. For
    instance, Neogene volcanics in Spain have yielded 'true' K-Ar dates of
    12 Ma as well as very well-defined ostensibly-inherited Rb-Sr isochrons
    in the 200-220 Ma range and less well-defined ones as old as 535 Ma
    (Munksgaard 1984). Quaternary basalts in Japan have yielded Sm-Nd
    'mantle isochrons' of 1.0 Ga (Togashi et al. 1992), amounting to a
    discordance of three orders of magnitude with other dating methods.

    Myth: Locally, isotopic results agree with the law of superposition;
    therefore, isotopic dating methods must, at least generally, be valid
    indicators of rocks ages.

    Reality Check: To begin with, when a 'stack' of lavas or tuffs shows a
    trend towards progressively younger isotopic results going upwards, it
    need not necessarily have anything to do with the actual age or ages of
    the 'stack' of extrusives in question. It may be simply an artifact of
    one or more of the following: magma chamber zonation, isotope
    fractioning, differential argon trapping and/or chance for trapped argon
    to escape, source-area effects, etc.

    As it is, there are numerous cases where there is an inverse relation
    ship between local stratigraphic successions and isotopic dates
    obtained, as discussed in my previous paper (Woodmorappe 1979, 1993). A
    more recent example of an inverse succession of isotopic dates is
    provided by a series of conventional K-Ar dates from lava flows in Israel:

         "Whole-rock K-Ar ages previously determined on volcanic rocks from
         the Atlit-1 borehole systematically decrease downhole from 203 Ma
         near the top to 123 Ma near the bottom. This age range is
         inconsistent with the Upper Triassic-Lower Jurassic stratigraphic
         constraints (Kohn et al. 1993, p. 17)

    It was claimed that this resulted from a selective thermal
    'rejuvenation' of the lower part of the 'stack' of lavas, based on a
    uniform Ar/Ar, and petrographic evidence.

    Inconsistencies between stratigraphic succession, and a suite of
    isotopic dates obtained, is a frequent occurrence. The alleged
    contamination of tuffs, tephras, etc., closely connected with studies of
    presumed human evolution (notably the KBS tuff controversy of the Koobi
    Fora area of Lake Turkana), is well known (e.g. Drake et al. 1998,
    Lubenow 1992, Milton 1997, Prothero and schwab 1996):

         'The example of the Koobi Fora and related formations of East Africa
         points out a number of problems typical of this kind of study. The
         radiometric dates provide the numerical ages, but they are subjected
         to many types of error and so had to be redone many times in several
         laboratories by three methods over 15 years before all the results
         were consistent and undisputed (Prothero and Schwab 1996, p. 445).

    In addition, the Hadar Formation of Afar, Ethiopia, famous for its
    australopithecus afarensis fossils, has recently yielded more than just
    the acceptable Ar/Ar and Ft dates ranging from 1.6 to 2.9 Ma. It also
    includes 'contaminant' dates, by both methods, which range in age from 5
    to 26 Ma (Walter et al. 1996, p. 69). Let us move beyond the
    paleoanthropological implications of these dates and consider them in
    the light of the law of superposition. Indeed, such inconsistencies
    are, in and of themselves, assumed to be an indicator of the
    unreliability of at least some of the dates obtained (or its converse).
      This face if obvious from the following:

         "The presence of geological error is evident when repeat samples
         from the same stratigraphical horizon don't produce consistent ages,
         and when the ages obtained from a given horizon are incompatible
         with those from strata immediately above and below (Fitch et al.
         1985, p. 611).

         The regularly-decreasing succession of isotopic ages must follow the
         stratigraphic succession. When this condition is satisfied, there
         is a high probability that the calculated ages are indeed those of
         the deposition dates (Bonhomme 1982, p. 5).

    Inversions between local stratigraphy and isotopic-dating results are
    hardly limited to ostensibly 'young' rocks, where one might rationalize
    the maximized impact of older contaminants on the 'young' dates. For
    instance, a dacitic volcanoclastic lithology yielding a U-Pb zircon date
    of 2697 Ma is overlain by a komatiitic-tholetic lavas which yield an
    older Sm-Nd date of 2826 Ma (Catell et al. 1984, p. 280). To explain
    away this conflict, the Sm-Nd result took the fall. it was relegated to
    a mixing isochron.

    Inclusion, claims of consistency of gross stratigraphic successions with
    older-to-younger sequences of isotopic dates, as an argument for the
    overall validity of isotopic-dating methods, openly begs the question.
      It is just another use of the CDMBN fallacy.

    Myth: If isotopic dating methods were invalid, we should not see an
    overall older to younger progression of isotopic dates relative to
    Fact: There are two tacit premises in this argument: 1) the trends
    seen in the literature reflect actual trends in dating results obtained
    from earth's lithologies, and 2) assuming the validity of premise (1),
    radioactive decay is the only manner by which a progression of dates
    could arise. Premise (1) is unlikely to be correct, and premise (2) is
    egregiously false.

    Let us first examine premise (1). The trends seen in the discrepant
    results themselves (in the table within the previous
    article--Woodmoreappe 1979, 1993) are at least partly an artifact of the
    selective publication of dating results. Less severly-deviant results
    are more likely to be published than more severely-deviant ones because
    the former are easier to assign to a geologic meaning than the latter.
      More importantly, dates which are 'too young' are more likely to be
    published than those which are 'too old' for the same reason.

    Moreover, the selective acceptance of dates, right from the earliest
    history from isotopic dating, had been predicated on the assumption that
    dating methods are valid and hence 'should' display a stratigraphic
    older-to-younger progression! This fact is obvious from the following
    discussion of early 20th-century isotopic dates, and how they had been
    evaluated for presumed correctness:

         'But in the end, he [Schuchert] concluded that the only viable
         approach was to accept from radioactive dating an age of 500 million
         years for the lower Cambrian, and to adjust the stratigraphic
         determination of the duration of each individual period using that
         as a standard. He believed that approached in this manner,
         radioactivity would make it possible to determine the rates of
         formation of the various strata, while stratigraphy, in turn, would
         provide an important check upon radioactive results (Burchfield
         1975, p. 205)

    Clearly, then, to the extent that a 'younging-up' trend appears to
    exist, it is hardly surprising. it may in fact be little more than a
    self-fulfilling artifact of this procedure.

    Let us now turn this discussion to the evaluation of any potential
    progression. To begin, this, we must solve the vexing problem of
    multiple biases in our dataset.

    And this is only the beginning. In order to validate premise (1) we
    would need to guarantee that the earth's surface is being sampled
    equally. To do this, we would need sampling of the crust on a grid
    pattern, as described by Patchett (1192, p. 482)/ We would subsequently
    need to correct for the bias caused by the greater overall area of
    outcrops of Mesozoic and Cenozoic igneous bodies with respect to
    Paleozoic ones. Apart from this, we would need to account for the
    biases which exist solely as a result of the unequal abundances of
    potentially-dateable igneous materials throughout the Phanerozoic
    column. such biases are particularly glaring for certain segments of
    the column:

         "Fourth, radiometric data for the Cretaceous exceed those for all
         but late Cenozoic parts of the geologic column because of the
         abundance of volcanic ash, bentonite beds, and glauconites in global
         Cretaceous marine sections (Kauffman 1979, p. A445).

    Only by fulfilling all of these requirements could we have some basis of
    deciding if premise (1) is correct. and if it is, only then could we
    determine if a progression exists and, if it does, if it is a
    particularly strong one.

    I have by doubts about the existence of a strong progression,
    particularly when the aforementioned Meso-Cenozoic bias is taken into
    account. In fact, as noted below, most results of comparative dating
    methods are discordant. This also means that, were all these dates to
    be strongly bracketed biostratigraphically, there would only be a welter
    of contradictions between isotopic dates and biostratigraphy. thus, if
    a progression between the two system surfaced at all, it would probably
    be a weak one, and then accompanied by a very considerable scatter of
    data points.

    Let us now examine a clear-cut case, within, uniformitarianism, where an
    'age' progression and agreement with biostratigraphy had not been
    accepted as ipso facto evidences for the validity of the dates. For a
    time in the 1950's and 12960's sedimentary rocks had been dated directly
    bu using the K-Ar and Rb-Sr methods on certain clay minerals (such as
    presumably-authigenic illite). With the occasional exception of
    glauconite dating (discussed earlier), such attempts have been virtually
    abandoned (for time-scale purposes) since they produce discrepant
    results in the overwhelming majority of cases (Russel 1995, p. 175). In
    fact, as noted in my 1979 work, agreements with 'reliable' values for
    the time scale are probably little more than fortuitous (see also
    Harland 1990, p. 76). Ironically, however, no attempts (at least of
    which I am aware) have been made to even consider the possibility that
    dates from igneous minerals (that are biostratigraphically-bracked, of
    course) may also be fortuitously in agreement with each other and with

    Now consider Premise (2). Is radioactive decay the only means by which a
    trend could arise? Certainly not. For Instance, let us consider the
    relative abundance of the major groups of clay minerals in shales
    through Phanerozoic time (Weaver 1967). Illite decreases sharply from
    Paleozoic through Tertiary, while smectite increases even more
    dramatically from Paleozoic through Tertiary. No one is, of course,
    suggesting for a moment that this trend constitutes evidence that illite
    undergoes radioactive decay to smectite over hundreds of millions of
    years of time! After all, clay minerals are not radioactive. Yet, if
    one were to follow the logic of the apologists for isotopic dating, one
    would almost have to do so!

    What about all the date from igneous rocks? Here, we need to remember
    the non-geochronometric means (such as isotope fractioning,
    Magma-chamber zonings, etc.) by which an overall trend could arise
    (between progressively younger isotopic dating results, and local
    stratigraphy, and even global biostratigraphy). some current
    creationary research (e.g., austin and Snelling 1998, Snelling 1998) is
    along these lines.

    Myth: If isotopic dating methods were false, we should not expect to
    see less discordance among younger dates than older ones.

    Face: To my knowledge, this assertion has never been proved. I have
    seen much discordance among Tertiary Rocks just as I have seen it in
    Precambrian ones. And, to evaluate this claim, we would need to
    overcome all of the rock-collection and dating biases discussed in the
    previous entry. In particular, if we were to guarantee the publication
    of all 'inherited' isochrons, we would undoubtedly see many severely
    discordant results between the 'true' Tertiary values and the much-older
    'inherited' ones.

    We would also need to evaluate the geochemical dynamics of inheritance.
      If it turned out that all 'daughter' products tend to become
    geochemically attenuated with stratigraphic progression, this would not
    only explain the progressive 'younging' of all the dating results, but
    also any trend in decreased discordance between them.

    Myth: If isotopic dating methods were false, we would expect to see as
    many 'future' ages as million to billion year ages, and/or as many zero
    ages as the same.

    Reality Check: These arguments may sound intuitively appealing to the
    uninitiated, bu they are actually somewhere between extremely dubious
    and bogus. In actuality, what kind of 'dates' we would obtain on a
    young earth would very much depend upon many things, not the least of
    which is the dynamics of inheritance of the isotopic systems. If, as
    discussed below, the retention of argon in magmas is proportional to
    rate of the mobilization of the magma, it would not be surprising that
    most ancient rocks (dating form the Creation or the Flood) have built-in
    positive ages, and very few have zero or future ages. A similar line of
    reasoning holds for the inheritance of isotope systematics used in other
    dating methods.

    This is not to say that there are no zero or future ages derived from
    ancient rocks. future ages do occur, and are relatively common when
    geochronologists figure model ages using the Sm-Nd method (Schere et al.
    1997, p. 73). In particular, these negative-slope isochrons
    ('futurechrons') have also been seen in the Sm-Nd dating of garnet
    (Jagoutz 1994, p. 156). Negative ages also occur among Rb-Sr whole-rock
    isochrons (Gazis et al. 1998, and citations). Future ages are fairly
    common as a result of the so-called reverse-discordance that occurs in
    some U-Pb dates:

         "Reverse discordance is common in young monazites. . . . For
         tertiary and even many Mesozoic monazites, the excess 206Pb is
         sufficient to produce negative or 'future 207/207Pb ages (Mattinson
         et al. 1996, p. 355).

    However, most future ages never see the light of day. Very likely,
    negative ages and zero ages are seldom published because they are not
    usually considered to have any geologic meaning in the
    evolutionary-unformitarian paradigm. for example, SNelling (1995)
    provides an example of a hertofore-unpublished zero Th-Pb age.

    >>**First, your plot of computed verses expected ages illustrates Point 3
    >>-- if an isotopic date fits the expected date it is accepted, if not, it
    >>is rejected.
    >>**Second, Creationists completely reject all isotopic dates, so it is
    >>just as irrelevant for there to be too young of ages as too old of ages.
    >>We don't need for isotopic dates to be young, we don't need them at
    >>all--they are irrelevant.
    >You didn't answer the question. You claimed in your original post that
    >creationists didn't have a problem with the measurement of isotopes in a
    >rock. The dates are straightforward mathematical manipulation of variations
    >in percentages of various isotopes. Even if the dates are all wrong, they
    >represent variations of chemical composition. So explain why the isotopes
    >vary systematically? That you didn't answer.
    I could care less why they vary systematically or unsystematically.
      And, as Woodmorappe explains above, it is highly unlikely that they are
    systematic nor in accord with any biostratigraphy.

    >>**I am fully aware of Stassen's article and as I noted in another reply
    >>to this thread, Stassen's criticisms are bogus. I remember when Stassen
    >>first wrote this article in part due to arguments we had been having on
    >>T.O. I wasn't impressed then and I'm not impressed now. He created a
    >>useless strawman [i.e. the rigged results] and appears to not have
    >>carefully read Austin's Grand Canyon book.
    >>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.
    Isochrons are often done on whole rock. Using single minerals does not
    guarantee correct results. Woodmorappe goes into great detail about
    this too in the same book I quoted extensively from above. You will
    need to get the book, I'm not going to do anymore typing, it just takes
    too much time.


    "I have been shown that, without Bible history, geology can prove 
    nothing. Relics found
    in the earth do give evidence of a state of things differing in many 
    respects from the
    present. But the time of their existence, and how long a period these 
    things have been in
    the earth, are only to be understood by Bible history. It may be 
    innocent to conjecture
    beyond Bible history, if our suppositions do not contradict the facts 
    found in the sacred
    Scriptures. But when men leave the word of God in regard to the 
    history of creation, and
    seek to account for God's creative works upon natural principles, 
    they are upon a
    boundless ocean of uncertainty. Just how God accomplished the work of 
    creation in six
    literal days, he has never revealed to mortals. His creative works are just as
    incomprehensible as his existence."  Ellen Gould Harmon White,  1864

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