Radiocarbon Dating and Fossils

Discussion in 'Creation vs. Evolution' started by Administrator2, Jan 23, 2002.

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    Radiocarbon Dating

    THOMAS CASSIDY
    Originally posted by Blade:
    Yes, the older something gets, the less accurate carbon dating is. However, the "mistakes" that these "young earth" defenders point to are generally in the order of millions of years, not thousands. Carbon dating has shown animals (i.e., mammoths that were preserved in ice) to have been around for at least 20,000 years by carbon dating.
    As a scientist, I have no reason to doubt this dating. It has been replicated and no error has been found.


    As a former scientist specializing in the Nuclear Sciences, I find the major short-coming of Radiocarbon dating to be the assumption that carbon-14 production has been a constant throughout the period of time being tested for. Carbon-14 is continually formed in nature by the interaction of neutrons with nitrogen-14 in the Earth's atmosphere; the neutrons required for this reaction are produced by cosmic rays interacting with the atmosphere. If the nature of the atmosphere has changed sometime in the past, then the production rate of carbon-14 may also have changed. If the atmosphere were at one time thicker, for example, less carbon-14 would have been produced and migrated to the lower level of the atmosphere, giving the appearence of greater age due to a lesser amount of carbon-14 present in the test subject. Those who postulate a steady-state of radiocarbon production would see the lesser amount of c-14 as an indication of radiometric decay thus indicating an older specimen.
    However, if the rate of c-14 production had been lower in the past, the age of the specimen would be much younger than the steady-state theorist's hypothesis.

    There are many Christians who postulate a pre-flood atmosphere which was thicker than present, often including a "vapor canopy" in their theory which could account for the lower levels of c-14 in those animals who lived prior to the postulated flood which marked the collapse of said vapor canopy.

    Radiocarbon dating is, at best, an educated guess dependent on the foundational assumptions of the testing method. If those assumptions are flawed, the results will be equally flawed.

    Or we can go with this report on the problems associated with radiocarbon dating: http://www.esd.ornl.gov/projects/qen/nerc14C.html


    JOHN2001
    A partial chronology of the development of the method.

    Here is a partial chronology of the development of the calibration of 14C, which includes consideration of sources of fluctuations in the background level of 14C.

    Much of creationist commentary on the possible errors in 14C is intended to portray the scientific community as being either incompetent or dishonest regarding such issues as the consideration of potential errors in radiometric dating methods. Creationists never discuss the fact that given these analyses, scientists have found ways of identifying and mitigating the effects of these potential sources of error.

    What follows is a summary from chapter 14.1.3, p.364-366 of Dickin [1995]:

    1941 Thellier proposed that Earth's magnetic field experiences secular variations.
    1949 Arnold and Libby publish radiocarbon dates of items of known age.
    1952 Libby publishes first book on radiocarbon dating.
    1954 Forbush observed that the 11-year cycle of sunspot activity was inversely correlated with cosmic-ray intensity.
    1955 Suess proposed dilution due to the burning of fossil fuels for the 2% depletion of 14C activity seen in 20th century wood compared to 19th century wood.
    1956 Elasser, et al. predicted variations in the cosmic ray flux due to secular variations in Earth's magnetic field.
    1958 de Vries found that 17-th century wood had a 2% higher activitythan 19th century wood.
    1961 Stuiver used historical records of sunspot activity to calculate cosmic ray intensity, and hence 14C production for the past 1500 years, and suggesting that the observations of de Vries, correlated with a sunspot minima.
    1965 Stuiver used more detailed records to confirm the correlation of a sunspot minimum with de Vries observations.
    1967 Bucha and Neustupny provided paleomagnetic intensity measurments that supported the existence of secular variations in the Earth's magnetic field first proposed by Thellier. They were able to model the variations of 14C production, and almost exactly match the deviations between the tree-ring and radiocarbon time scales.

    By 1969, it became apparent that calibration of the 14C dating method was both possible, and required, to make radiocarbon dates useful for the determination of calendar dates. Indeed, it is often material from prior to 1969 that creationists use as ammunition against the 14C dating method. One useful method of calibrating 14C is dendrochronology, or age dating by counting tree rings. The basic idea of calibration is simple. Plot the true date determined from counting tree rings versus the radiocarbon date. The result is a plot that can be used to both determine the actual original 14C/12C ratios (useful for studies in paleoclimatology) and can be used to convert radiocarbon dates of other samples into calendar dates.

    The first use of dendrochronlogy to calibrate 14C was made by

    1970 Furgeson used dendrochronology of bristlcode pines to calibrate radiocarbon dating back to 7484- years b.p. (before the present).

    Through comparison with tree ring dates, the 14C method has been calibrated back to more than 13,000 years before the present,

    1991 Becker, et al publish a stable dendrochronological calibration of 14C back to 11,000 years before the present using tree rings. The chronology consists of a 9,928-year absolutely dated dendrochronological record of Holocene oak (Quercus robur, Quercus petraea) and a 1,604-year floating Late Glacial and Early Holocene chronology of pine (Pinus sylvestris) from subfossil tree remains deposited in alluvial terraces of central European rivers.

    In addition, 14C dating has also been calibrated back to more than 30,000 years before the present using uranium-thorium (isochron) dating of corals [Bard, et al, 1990] and [Edwards, et al, 1993].
    While it is unlikely that 14C will be useful for objects older than 50,000 years, owing to the problems of background contamination
    [Dickin, 1995] and [Lowe, 1991], there is a recent paper by [Kitagawa, H., and van der Plicht, J., 1998] discusses calibration of 14C dating back to 45,000 b.p. using U-Th dates of glacial lake varve sediments (periodic sedimentary layers).

    References:
    --Arnold, J. R. and Libby, W. F. (1949) Age determinations by radiocarbon content: Checks of samples with known age. Science 110, 678-680.
    --Bard, E., Hamelin, B., Fairbanks, R.G., and Zinder, A., (1990), Calibration of the 14C timescale over the past 30,000 years using mass spectrometric U-Th ages from Barbados corals, Nature, 345, 405-410.
    --Becker, B., Kromer, B., and Trimborn P., 1991, A stable-isotope tree-ring timescale of the Late Glacial/Holocene boundary: Nature, vol. 353 (17 Oct 1991), 647-649.
    --Dickin, A. P. (1995), Radiogenic Isotope Geology, Cambridge University Press.
    --Dalrymple, G. Brent, (1991), The Age of the Earth. California: Stanford University Press, ISBN 0-8047-1569-6.
    --Edwards, R. L., Beck, J. W., Burr, G. S., Donahue, D. J., Chappell, J. M. A., Bloom, E. R. M., Druffel, E. R. M., Taylor, F. W., 1993, A large drop in atmospheric 14-C/12-C and reduced melting in the Younger Dryas*, documented with 230-Th ages in corals: Science, vol. 260 (14 May 1993), 962-967
    --Furgeson, C. W. (1970), Dendrochronology of bristlecone pines, Pinus aristata. Establishment of a 7484-year chronology in the White Mountains of eastern-central California, USA. In: I. U. Olsson (Ed.), Radiocarbon Variations and Absolute Chronology, Proc. 12th Nobel Symp. Wiley, pp. 629-40.
    --Kitagawa, H., and van der Plicht, J., (1998), Atmospheric radiocarbon calibration to 45,000 yr B.P>: Late glacial fluctuations and cosmogenic isotope production, Science, v. 279, 20 Feb 1998.
    --Libby, W. F. (1952) Radiocarbon dating, University of Chicago Press.
    --Libby, W. F. (1970) Ruminations on radiocarbon dating In: I. U. Olsson (Ed.), Radiocarbon Variations and Absolute Chronology, Proc. 12th Nobel Symp. Wiley, pp. 629-40.
    --Lowe, J. John, ed. (1991) Radiocarbon Dating: Recent Applications and Future Potential, Quaternary Proceedings, Number 1, 1991, Published for the Quaternary Research Association, Wiley.

    * * * * *

    [Administrater: the following is from a different, related thread]

    HELEN
    [In response to the protest that there is no circularity in fossil dating/rock strata dating]

    Rocks that contain fossils are much easier to interpret chronologically than rocks
    without fossils. http://www.cce.umn.edu/dis/courses/GEO1002_4503_03.www/


    DATING INDIVIDUAL FOSSILS
    Paleontologists use many ways of dating individual fossils in geologic time.

    1.The oldest method is stratigraphy, studying how deeply a fossil is buried. Dinosaur fossils are usually found in sedimentary rock. Sedimentary rock layers (strata) are formed episodically as earth is deposited horizontally over time. Newer layers are formed on top of older layers, pressurizing them into rocks. Paleontologists can estimate the amount of time that has passed since the stratum containing the fossil was formed. Generally, deeper rocks and fossils are older than those found above them. http://www.zoomdinosaurs.com/subjects/dinosaurs/dinofossils/Fossildating.html

    http://www.rael.org/int/english/evidence/evidence/body_evolution2.html
    M.C. van Oosterwyck-Gastruche
    CHALLENGING THE DATING OF GEOLOGIC AREAS
    The isotopic measurements, "dating" geologic eras,
    have no chronological meaning.
    But the conclusions of the manuals are, as we know,
    diametrically opposed. I started informing myself by
    asking my fellow geologists. Above all I wanted to know
    the chronological points of reference which had been used
    to validate the millions of years of evolution and allowed
    the selection of geochronological data in order to keep
    only the good results ("best values"). They confessed they
    did not know about them but they advised me to consult
    the Holmes' manual "Physical Geology" (1965), because
    "everything was in it."

    The geological
    time measured by the decay of a radioactive isotope was
    essentially the work of Arthur Holmes (1890-1963), who
    shared Lyell's "creed". In fact, he confirmed Lyell's thesis
    by giving the oldest ages (from 3000 to 600 millions of
    years) to Archean or Precambrian formations, where
    elaborate life signs had not yet been discovered.
    Moreover, his "Phanerozoic time scale", from 600 million
    years ago to our era, confirmed evolution observed in
    Lyell's stratigraphical scale, proving the "emergence of
    life" and officially dating the main recorded "events" within
    the geological eras.

    In spite of his apparently convincing palaeontological
    documentation and his impressive mathematical formality,
    Holmes' geological scale appears to be very confused. The
    dates of his "Phanerozoic scale" are among the most
    doubtful, as was noticed on several occasions, the first of
    which during a meeting which took place the very year of
    his death. They reproached him at that time for leaning on
    a too limited number of mostly questionable data
    (Harland, Smith and Wilcook ed., 1964). Later, York and
    Farquhar (1972), disconcerted by the profusion of
    abnormal ages and asking for more data, ironically wrote
    about Holmes' scale, "These two necessary
    presuppositions, precise stratigraphical localisation and
    reliable radiometric dating, seem to exclude one another:
    we almost end up at a geological uncertainty principle".

    The worrying point is the following: these isotopic
    determinations which provide the millions of years which
    are so well recieved, (and so controversial for specialists)
    which proved "the Emergence of Life," were never applied
    to any fossil or to any strata in which these fossils are
    buried; sedimentary rocks not lending themselves to
    radio-dating. The material dated is generally a lava flow
    covering these fossiliferous layers, the lava flow
    supposedly intimately linked to the evolution process as
    designed in the "actualist" framework which inspired
    Holmes' scale, all without a shadow of proof.

    Another disconcerting fact: the "correct" ages which
    appear are the result of a selection (Holmes, 1965), the
    author having only accepted the "best values" (those
    confirming Lyell's stratigraphical scale), rejecting the
    others as "anomalous."

    The hypothetical character of such a construction, valid if
    Lyell's theory is exact, is underlined by geochronologists
    themselves, beginning with the authors of the
    Potassium-Argon dating method, Dalrymple and Lanphere
    (1979). Fitch, Hooker and Miller (1978), confronted by field
    problems, debated in "Geological Background to Fossil
    Man" on the capacity of radioactive decay techniques to
    provide real ages for principal "events" of the African
    Oriental Rift (East Rift Valley) linked to the "emergence
    process." They note that the phenomenon of radioactive
    decay gives dates for "events" taking place in the rocks
    but on the basis of temperature changes and/or of the
    arrival of solutions. They emphasize, "It is important to
    realise that exactitude of ages obtained from this means
    depends on the integrity and condition of preservation of
    isotopic recording of rocks (since they change with the
    above factors and with the alteration of mineral
    constituents) and it also depends on our interpretation of
    radio-isotopic experiments." This is essentially based "on
    our interpretation of data related to fossil fauna" (what is
    unsaid is that the interepretation is by proponents of the
    the actualist and Evolution theory framework), since
    "combination of stratigraphy of rocks and stratigraphical
    palaeontology gives us the geological time scale."
    Unfortunately, they note that the results obtained in the
    Oriental Rift, far from confirming the actualist hypothesis,
    remain particularly strange. Furthermore, these authors
    conclude: "The two principal tools of geochronology being
    equally fallible, the best is to use them jointly and not to
    oppose them".

    Therefore the principle tool is not geochronology, but
    Lyell's scale, and the sledgehammer argument, which
    seems to lack any sense, remains the "characteristic
    fossil," the isotopic results being filtered according to its
    theoretical age.



    ------------ http://www.emporia.edu/earthsci/student/nang/treering.htm
    Limitation of Dendrochronology

    Although growth rings are useful for tracing the past, not all tree-rings are suitable for dating. Specific limiting factors, both external and internal, affect the plant growth rings. External factors are water, temperature, light, CO2, Oxygen, and soil minerals. Internal factors are growth regulators, enzymes, and water. These factors can be the result of external factors as well. Each ring is the result of both factors within a single year. Growth begins in spring, and ends in summer or early autumn. When one or more factors are limiting, distinct growth rings, or layers are formed. It is possible that no growth rings are formed under favorable conditions, or, one or more growth rings can be formed during an unfavorable year.

    Therefore, there are many species in different geographic areas thart are not suitable for applying dendrochronology, because their growth rings are inconsistent. For example, Cupressus arizonia, several species of Juniperus, and most of the subtropical and tropical trees are not suitable for dendrochronology (Fritts, 1976). However, recent study shows that tree-rings study can be applied at the tropical areas where there is a seasonal rainfall. Growth rings of teak (Tectona grandis) and pines (Pinus spp.) from Indonesia and Thailand are significantly related to the variation of rainfall and ENSO (El Nino/Southern Oscillation). Geographical areas where suitable trees are available, are shown in the map.

    Problems and Difficulties

    Tree-rings can estimate the minimum-limiting age. However, there are some difficulties in defining the age of the tree.

    Determination the ecesis: the estimation of the length of time between land surface stablization and seedling establishment
    Determination the year between seedling and the stage at which tree-rings samples can be taken
    Determination of the oldest tree inthe area
    False rings
    Missing rings: years of extreme environmental condition
     
  2. Administrator2

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    DAVID PLAISTED

    From what I have heard, there are some problems with Ferguson's tree ring chronology. A standard statistical procedure called "whitening" was never applied to it. Typically there are many ways of matching tree ring sequences, and the matches that Ferguson chose may have been influenced by radiocarbon dating. Whitening tends to greatly reduce the possible numbers of choices. I also got an email from someone who had intimite knowledge of Ferguson's data and expressed strong skepticism about it. But anyway, it would be good if Ferguson's data were made public (if this has not yet been done) and independent analysis could be done on it.

    David Plaisted
     
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    EARL DETRA
    "Someone" expressed skepticism? Ferguson "might have been influenced?" I can't think of more devastating arguments, David. Have you read Ferguson's paper? What data does he show? Usually in peer-reviewed literature some data must be presented to make the author's case. What more would you want to see? What is whitening? When is it used? Perhaps Ferguson didn't feel it was necessary. Maybe the interpretations were clear to him and no reduction of alternatives was necessary.
     
  4. Administrator2

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    DAVID PLAISTED

    Here is the email about tree ring dating; it was sent to me on February 11, 1998:

    As one who has taught dendrochronnology, I have a few opinions on this particular subject. Also, one of my graduate students went to work for Ferguson in his lab at U of A, and in fact was the curator of his work after his death, and is presently probably the only one who knows anything about how he [Ferguson] produced the bristlecone chronology. Another of my graduate students gave a seminar to the lab on dendrochronology of fossil trees and had ample opportunity to analyze the procedures there, and to work with Ferguson for a while. I can say on pretty firm grounds that the Bristlecone chronology before 4000bp is fraught with problems and unanswered questions. While Ferguson was alive, he never allowed anyone to analyze his original data or the bases for the many suppositions that went into the establishment of the chronology. Thus the chronology was not subjected to the normal rigors of science. This is regrettable, because I believe he was a careful and sincere scientist. Of course one could always excuse Ferguson for not revealing the bases of his decisions (for example, the most important rings in any chronology are the "missing rings" which have to be added by the investigator). But suffice to say the chronology before 4000bp is entirely dependent on C14 dates of the wood, and is thus tautologous. This does not mean it is meaningless or necessarily wrong, just that I wouldn't base too much on it.


    A good web link about tree ring dating and possible problems with Ferguson's chronology:
    http://www.grisda.org/origins/22047.htm

    It also mentions "whitening."

    Dave Plaisted

    [ January 29, 2002: Message edited by: Administrator ]
     
  5. Administrator2

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    PATRICK PARSON

    The Barbarian says:
    The questions about C-14 calibration are put to rest by the work done on
    varves in a Japanese lake:
    http://abcnews.go.com/sections/science/DailyNews/carbon0220.html


    Unless someone can show that many years had more than one summer and more
    than one winter each, there's no way to explain away the evidence.
     
  6. Administrator2

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    RADIOCHEMIST

    The creationists talk as if carbon-14 is the major support for
    believing that the world is very old. There are many other dating methods that
    agree on the age of the earth as being approximately 4.5 billion years.

    The important thing to remember about any dating method is that
    they are not perfect. All have potential problems but that does
    not mean that they are useless - far from it. It reminds me
    of a conversation that A. Lincoln had with someone about horses.
    He said that all horses have faults. Back in the days when
    horses were the only form of transportation, almost everyone
    had them. And yet as Lincoln noted, all horses have faults. That
    did not make them useless. People learned to use them in spite
    of their faults. Some horses were lazy, some did not obey
    certain commands and had various other problems. But the fact
    there are flaws in dating methods does not make them useless.
    Scientists learn to understand the potential sources of error
    and to correct for them. In the case of carbon-14, it is true
    that it depends on certain assumptions. But those assumptions
    can be checked and if necessary corrections can be made if the
    assumptions are not quite right. And that has been done in the
    case of carbon-14 to the extent that it is a highly useful dating
    methods.

    Corrections have been and are
    being made with regard to this method.

    RADIOCHEMIST
     
  7. Administrator2

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    RADIOCHEMIST

    I will quote part of Thomas Cassidy's post and then comment on it
    below.
    <BLOCKQUOTE>quote:</font><HR>THOMAS CASSIDY: There are many Christians who postulate a pre-flood
    atmosphere which was thicker than present, often including a "vapor
    canopy" in their theory which could account for the lower levels of
    c-14 in those animals who lived prior to the postulated flood which
    marked the collapse of said vapor canopy.

    Radiocarbon dating is, at best, an educated guess dependent on the
    foundational assumptions of the testing method. If those assumptions
    are flawed, the results will be equally flawed.

    Or we can go with this report on the problems associated with
    radiocarbon dating: http://www.esd.ornl.gov/projects/qen/nerc14C.html"
    <HR></BLOCKQUOTE>

    Thomas Cassidy talks favorably of a vapor canopy and
    unfavorably of C-14 methods. The fact is that there is zero scientific
    evidence for a vapor canopy and an abundance of evidence for the
    general usefulness of the C-14 method. How then is he able to point
    to a scientific site that discusses some weaknesses of the method?

    In order for the weaknesses of the C-14 method to be of any use to
    creationists in their ideological battle, the method must be grossly
    and wildly inaccurate without any hope of improvement. In other words
    a date of 40,000 years by C-14 would need to be in error by several
    hundred percent so that, for example, the true age is actually 6,000
    rather than 40,000. But the creationists are out of luck on that sort
    of wild error. What is being discussed in scientific circles, when
    they talk about the the weaknesses of C-14, are errors that do not
    give the creationists much comfort. For example, to historians who
    study ancient things, the C-14 method can have an error of plus or
    minus 10 or maybe even 20 percent. For an object 20,000 years old,
    this limits the amount of useful information, since the C-14 age
    might be anywhere in the range of 16,000 to 24,000 years. It is
    the effort to reduce these uncertainties that occupy much of the
    time of the workers in this field. Obviously it would be more useful
    to know if an object is a certain age to within 100 years, rather
    than to an uncertainty of 3 or 4 thousand years. So great attention
    is given to the possibility of errors and attempts are made to
    reduce the uncertainty as much as possible. These methods and
    discussions are misrepresented by creationists as meaning that
    the method is totally unreliable. Nothing could be further from
    the truth. I suspect that more than 90 percent of the alleged
    weaknesses in the C-14 method do nothing at all to lend support
    to the creationist cause. Rather, these weaknesses involve very
    fine points of the method and are not related to any fundamental
    problem with the method. A close reading of the web site referred
    to by Thomas Cassidy supports this view.

    Thomas Cassidy says that the C-14 method is an educated guess. That
    is a gross misrepresentation. He also fails to mention
    that the fundamental assumptions have been tested many times and
    that the C-14 method has been calibrated to adjust for errors
    in the underlying assumptions. An important factor in determining
    the usefulness of the method is the nature of the question to be
    answered by the method. The C-14 method was entirely adequate to
    determine whether the Shroud of Turin was the burial shroud of
    Christ (it was not) but it is not good enough to determine the
    precise year in which the shroud was made. It is this type of
    fine point which is of interest to science and underlies most of
    the discussion of the weaknesses of the method. I think it can be
    said without fear of contradiction, that the C-14 method is
    easily good enough to disprove the theory that the earth is
    less than 10,000 years old. It is a robust method for that
    purpose.

    RADIOCHEMIST
     
  8. Helen

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    Came across the following quotes this evening and thought this was an appropriate thread for them:

    ==========

    "It is self evident that a contaminated sample will give an erroneous date, but it is frequently impossible to ascertain if a sample
    has indeed been contaminated."
    R.S. Bradley, Quaternary Paleoeclimatology, London, Boston: Allen and Unwin, 1985, p. 54

    "Relative ages are always subject to interpretation, and radiocarbon dates are often ignored or dismissed as a "bad date" if they
    do not fit an a priori hypothesis."
    T.A. Thompson, G.S.Fraser and G. Olyphant, Establishing the altitude and age of past lake levels in the Great Lakes, Geological Society of America Abstracts with Programs 1988, 20(5) p. 392

    "In the light what is known about the radiocarbon method and the way it is used, it is truly astonishing that many authors will cite
    agreeable determinations as a "proof" for their beliefs. The implications of pervasive contamination and ancient variations in
    carbon-14 levels are steadfastly ignored by those who based their argument upon the dates. The radiocarbon method is still not
    capable of yielding accurate and reliable results. There are gross discrepancies, the chronology is uneven and relative, and the
    accepted dates are actually selected dates. ’This whole blessed thing is nothing but 13th-century alchemy, and it all depends
    upon which funny paper you read’."
    Robert E. Lee, Radiocarbon: Ages in Error, Anthropological Journal of Canada, Vol 19, No 4 (1981) pp. 9-29

    "C-14 dating was being discussed at a symposium on the prehistory of the Nile Valley. A famous American colleague,
    professor Brew, briefly summarized a common attitude among archaeologists towards it as follows: "If a C 14 date supports our
    theories, we put it in the main text. If it does not entirely contradict them, we put it in a footnote. And if it is completely out of
    date, we just drop it. Few archaelogists who have concerned themselves with absolute chronology are innocent of having
    sometimes applied this method, and many are still hesitant to accept C 14 dates without reservation."
    T. Säve-Söderbergh and Ingrid U. Olsson, C14 Dating and Egyptian Chronology, in Ingrid U. Olsson (ed.) Proceedings of the Twelfth Nobel Symposium. New York: John Wiley & Sons, Inc and Stockholm: Almqvist & Wiksell, 1970

    "The Carbon-14 contents of the shells of the snails of Melanoides tuberculatus living today in artesian springs in
    southern Nevada indicate an apparent age of 27,000 years."
    Alan C. Riggs, Science, vol 224 (1984) 58-61
     
  9. The Galatian

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    There are a lot of errors in that one, some of them so fundamental that it's hard to imagine any scientist making them.

    For example, mollusk shells from aquatic or marine species cannot be used for carbon-14 dating, because most of their carbon comes from ancient dissolved carbon from rocks. The person who gave that to you, Helen, was almost certainly aware of it. Shame on them.

    Of course, there are direct ways to calibrate changes in carbon-14 in the atmosphere. Here's one easy one:

    http://www.cio.phys.rug.nl/HTML-docs/Verslag/97/PE-04.htm

    The variations are easily correlated with dates, to get a more accurate method.

    Note that the lake lamina are also varves, i.e. they are seasonal, one light,and one dark one per year. They are checkable by the varying pollen content, and can be observed in the process of being laid down today.

    Evidence trumps anyone's second-hand opinion.
     
  10. Edgeo

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    Right, I imagine that you just accidentally came across these quotes...

    What type of samples is Bradley talking about? It seems to me that this statement is not quite complete. At any rate, if contamination is present it can usually be detected post-analysis by several means, primarily by double sampling, etc.

    Yes, relative ages are interpretive, but they are interpretive based on some fundamental principles that have yet to be found faulty.

    And yes, some 'interpretive' relative ages are considered more reliable than radiometric dates. This is because of potential sources of error that you seem to think geochronologists are unware of.

    Why is the word 'proof' in quotation marks here? Does it mean that the dates are not really used as proof? If not, why is the author implying so? Do you realy believe that all samples are contaminated? If so, why are there any concordant dates at all? Would you expect the contamination to be exactly the same in every sample?

    I am sorry but I cannot take seriously someone who refers to all papers on carbon dating as 'funny papers.' It makes the entire argument non-credible. Clearly, someone is grinding an axe.

    So, you think that we should include dates that are thought to be contaminated anyway? You are one tough audience. You complain about our 'assumptions' and yet when we understand a sample to violate an assumption (contamination) you also castigate us for not using the bad data!

    I believe that Galatian has explained this to you above. I am quite certain that you are being deceived by whoever collected these quotes.

    [ June 29, 2003, 09:28 AM: Message edited by: Edgeo ]
     
  11. Helen

    Helen
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    Yes, I did run across them quite accidently on a Swedish page that had about half English on it. I was following someone's link on a different subject and got interested in some of the links on THAT page, sorry.

    And whether or not you folks like the quotes, I have been aware of them before and they are valid. Radiocarbon dating is not valid for historical dating.

    When one of my boys was little, and his big brother was teaching him how to play poker ( :rolleyes: ), the younger one at one point spread all the cards out, face up, on the table and picked the best five he could find. He then declared, "Look at the good hand I got from the cards!" (or something like that). No, he PICKED a good hand from all the possibilities there; his good hand was not the result of what the cards actually "gave" him. Radiocarbon dating reminds me of that incident.
     
  12. The Galatian

    The Galatian
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    How did it happen that precisely the "good hand" ended up in each one of those millions of varves in that Japanese lake?

    That seems so incredibly lucky as to suggest that maybe the evidence is what it appears to be.

    Quotes, of course, are not evidence. They are merely (possibly accurate) representations of what people thought at one time.

    They never overrule evidence.
     
  13. Helen

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    Don't change the subject, Galatian. I know it is what you prefer doing to avoid uncomfortable evidence, but see if you can restrain yourself here, OK?
     
  14. Edgeo

    Edgeo
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    Actually, they are often very valid as you have been shown above. Why do you not address any of my points and simply reassert your opinion?

    As in poker, any radiometric date 'hand' can be good, if you know what you are doing. For instance, if I get a carbon date of greater than 35ky, I might start to suspect that the sample is beyond the capabilities of my method and that the actualy age is greater than the upper limit of my method (unfortunately, your professional creationists don't tell you things like this). In this case, I might consider folding my 'hand' if other data conflict with the date. Furthermore, I might ignore this data point or make it a footnote. This is a smart move, and it is not 'picking a good hand.'

    In another case, I may suspect a certain age for a sample that would alter our understanding of human pre-history. If I were to obtain a supporting date by radiocarbon methods, I draw an ace. Then if other samples corroborate the first, I draw more aces and soon become famous, though probably not wealthy.

    I really wish you would address my criticisms of the quotes that you posted earlier. They really do not, in themselves, validate your opinion on radiocarbon dating because they are partly out of context and partly based on unscientific bias. Really, calling all papers on carbon dating 'funny papers' is not very professional and carries little credibility with me. And applying radiocarbon dating to shells of sea creatures is an egregious misapplication of the method. Basically, I have to say that your quotes are without any real merit whatsoever.
     
  15. Peter101

    Peter101
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    Helen,

    I would like to bring to your attention some mistaken information on your (Setterfield's) web site on the subject of carbon-14. You have been shown this problem before, but so far have not acknowledged that it is bad information. Here is the quote from an article by Trevor Major on C-14.

    "Radiocarbon dating assumes that the carbon-12/carbon-14 ratio has stayed the same for at least the last hundred thousand years or so. However, the difference between production and decay rates, and the systematic discrepancy between radiocarbon and tree-ring dates, refute this assumption."
    ------------------------------------------------
    No Helen, the above statement has been incorrect for the last 20 years. The method does not assume that the C-12/C-14 ratio has stayed the same for at least the last hundred thousand years or so. Modest errors are produced if that assumption is made, so for the last 20 years or more, C-14 dates have been corrected for the well known fact that the C-12/C-14 ratio has not been perfectly constant during the time frame for which the method is valid.

    Now my question to you is this; Will you not acknowledge that the quoted statement is in error? If so, let us know when it will be removed from your site. If you do not accept that it is a mistake, please defend the statement, because it needs some defending.
     
  16. Peter101

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    &gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;As a former scientist specializing in the Nuclear Sciences, I find the major short-coming of Radiocarbon dating to be the assumption that carbon-14 production has been a constant throughout the period of time being tested for.&lt;&lt;&lt;&lt;&lt;&lt;

    Thomas Cassidy apparently wrote the above but it seems that he has only a vague idea of the details of C-14 dating, because Cassidy is mistaken in the above comments, as is Setterfield.

    [ June 30, 2003, 10:28 PM: Message edited by: Peter101 ]
     

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