Hiding the Numbers to Defame Radiometric Dating
A Few Examples of the Many Misused References in
Kevin R. Henke
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Woodmorappe (1999) presents numerous examples of what he claims are "discrepant" radiometric dates that contradict each other, fossil data, field structures and/or stratigraphic evidence. For example, Woodmorappe (1999, p. 41) quotes the following statement from Swisher et al. (1993, p. 1994) to "demonstrate" that dates from Evernden et al. (1964), which were once highly regarded and characterized as state-of-the-art, are now considered unreliable:
“The same unit was most likely the one dated by Evernden et al. (1964) at 66.4 Ma [Ma = millions of years]. These ages are most likely too old, owing to the inclusion of detrital grains in the mineral separates.”
Yet, how anomalously old are Evernden et al.'s results? We find the answer in the proceeding sentences, which Woodmorappe (1999, p. 41) chooses to ignore. Here's a more complete quotation from Swisher et al. (1993, p. 1993-1994):
“Obradovich and Cobban (1975) and Obradovich (1984) dated biotite from dacitic pumice located approximately 22 [meters] above the K-P [Cretaceous-Tertiary (Paleocene)] boundary at 65.9 Ma by K-Ar and 65.8 +/- 0.3 Ma (2 sigma) by 40Ar/39Ar methods. The same unit was most likely the one dated by Evernden et al. (1964) at 66.4 Ma. These ages are most likely too old, owing to the inclusion of detrital grains in the mineral separates.”
Swisher et al. (1993, p. 1993-1994) are arguing over trivial errors of about 1% and Woodmorappe (1999, p. 41, 52) is misleading us into believing that these errors are huge and fatal to radiometric dating!
In another example, Woodmorappe (1999, p. 40-41) quotes Prothero (1994, p. 60) and argues that K-Ar dates from Evernden et al. (1964), which had been used to calibrate the Eocene-Oligocene boundary of the geologic time scale, were later shown to be "unreliable":
“When Carl Swisher of the Institute of Human Origins in Berkeley began to redate the Flagstaff Rim ashes in 1989, he discovered something shocking. Many of the K-Ar dates first run by Jack Evernden and Garniss Curtis in 1963 were drawn from contaminated samples. These dates (Evernden et al. 1964) had served as the basis for dating the North American mammalian chronology for over a quarter century, and everyone relied on them ...”
At face value, this quotation appears to be very bad news for the 1964 K-Ar dates and the ability to date the Eocene-Oligocene boundary. However, if subsequent sentences are quoted from Prothero (1994, p. 60), the situation changes:
“In some cases, the dates were off by as much as 2 million years. Flagstaff Rim Ash J, for example, had been K-Ar dated at 32.5 million years, but laser-fusion 40Ar/39Ar methods gave a date of 34.4 ...[reference to figure omitted].”
Clearly, this discrepancy is a serious challenge for geologists that want high resolution (less than 1% error) in the geologic time scale. However, Prothero’s relatively minor adjustment of the 32.5 million year old date to 34.4 million years provides no comfort to young-Earth creationists that want to destroy the reliability of the geologic time scale and reduce all dates below 10,000 years. Again, Woodmorappe (1999, p. 40-41) fails to mention the magnitude of the discrepancies because they hardly undermine the reliability of radiometric dating and support young-Earth creationism.
Another example of Woodmorappe exaggerating trivial errors in radiometric dating can be seen in his use (1999, p. 52) of Muecke et al. (1994, p. 229). Muecke et al. (1994, p. 229) concluded that there were 2-5 million year errors associated with some Late Cretaceous samples. However, when it's considered that dates for the Cretaceous samples are at least 75 million years old (Campanian-Maastrichtian and older), errors of 2-5 million years are too trivial for Woodmorappe's creationist agenda.
In another attempt to undermine radiometric dating, Woodmorappe (1999, p. 42) cites Kerr (1995, p. 27-28), where Dalrymple, Renne and other scientists "cannot agree" about which dates are "real" and which are "spurious" for some Siberian basalts and associated rocks:
"Over time, Dalrymple concludes, some of the argon-40 had leaked out of the trap's rocks, making them look 1 or 2 million years younger than they are. Renne, however, says that he is 'very confident about the new data' ... they did extensive argon-argon analyses that contradict Dalrymple's conclusions about the alterations of the trap rock. It's not that the trap rocks lost argon, Renne believes; instead, the intrusion carries extra argon-40 picked up before the minerals formed, giving a falsely older age."
So, how significant are the "discrepancies" in Kerr (1995)? Although Woodmorappe (1999, p. 42) is quick to tell his readers that the discrepancies involve 1-2 million years, which seem large, he does not tell us the ages of the samples. As discussed in Kerr (1995), Dalrymple and his colleagues are attempting to determine if massive 250 million year old volcanic eruptions in Siberia were synchronous with a severe extinction at the Permian-Triassic boundary. In other words, these scientists are arguing over errors of 1-2 million years for events that occurred 250 million years ago. Once more, Woodmorappe (1999, p. 42) is distorting arguments over errors of less than 1% just to make Dalrymple, other geochronologists and radiometric dating results look as bad as possible.
Woodmorappe (1999, p. 46) also cites the following statement from Baksi et al. (1993, p. 142) as an example of an unaltered rock that should be suitable for dating, but yet supposedly provided surprisingly "discrepant" dates:
“ ... we suggest the younger dates in the earlier study ... reflect partial loss of 40Ar from some specimens. Since all specimens in the earlier K-Ar study passed detailed petrographic examination, it is apparent that rigorous thin-section examination cannot unequivocally eliminate whole-rock basalts that have suffered partial post-crystallization loss of 40Ar*.”
However, Woodmorappe (1999, p. 46) omits some critical information on the magnitude of the "discrepancy". In context, Baksi et al. (1993, p. 142) states:
“Our age of 2.14 +/- 0.03 Ma (1 sigma error, including a term of +/- 0.5% to reflect uncertainty in the age of the monitor sample used) is ~3.5% older than the K-Ar date of 2.07 +/- 0.02 Ma ...[reference omitted]. We note that the published K-Ar dates ... [reference omitted] fall primarily into two groups, ~2.15 Ma and ~2.05 Ma. Averaging the former set yields an age of 2.13 +/- 0.02 Ma, and we suggest the younger dates in the earlier study ... [reference omitted], which average 2.04 +/- 0.02 Ma, reflect partial loss of 40Ar from some specimens. Since all specimens in the earlier K-Ar study passed detailed petrographic examination, it is apparent that rigorous thin-section examination cannot unequivocally eliminate whole-rock basalts that have suffered partial post-crystallization loss of 40Ar*.”
Once more, Woodmorappe (1999, p. 46) fails to mention that the "discrepancies" in Baksi et al. (1993, p. 142) are actually fairly minor from the perspective of the creation-evolution controversy.
Woodmorappe (1999, p. 74) also quotes the following section from Peterson (1994, p. 252) as an example of scientists "shopping around" for whichever dates best match their "preconceived notions":
"Bentonite beds are abundant in the upper part of Brushy Basin Member and have yielded 5 single-crystal 40Ar/39Ar dates ... A sixth date ... is almost certainly in error for several reasons. The age conflicts with another single-crystal 40Ar/39Ar age ... from the same unit ... , it does not agree with the other 40Ar/39Ar dates from southeastern Utah, and the stratigraphic relationships do not support the idea that the upper part of the Brushy Basin member is a diachronous unit that becomes markedly older progressing northward toward Dinosaur National Monument."
Despite Peterson's arguments, Woodmorappe (1999, p. 74) accuses Peterson (1994, p. 252) of "rationalizing away" the sixth date. However, Woodmorappe (1999, p. 74) liberally uses ellipses (...) in the Peterson (1994) quotation to blatantly hide the magnitudes of the dates. In context, the quotation from Peterson (1994, p. 252) reads:
"Bentonite beds are abundant in the upper part of Brushy Basin Member and have yielded 5 single-crystal 40Ar/39Ar dates ranging from 145.2 +/- 1.2 to 149.4 +/- 0.7 Ma from a measured section near Montezuma Creek in southeastern Utah...[reference omitted]. A sixth date in the same publication from Dinosaur National Monument gave 152.9 +/- 1.2 Ma, which is almost certainly in error for several reasons. The age conflicts with another single-crystal 40Ar/39Ar age of 148.3 +/- 0.3 Ma from the same unit at Dinosaur National Monument ... [reference omitted], it does not agree with the other 40Ar/39Ar dates from southeastern Utah, and the stratigraphic relationships do not support the idea that the upper part of the Brushy Basin member is a diachronous unit that becomes markedly older progressing northward toward Dinosaur National Monument."
The discrepant sixth date of 152.9 million years is not wildly different than the other five dates of 145-149 millions of years. As usual, Woodmorappe (1999, p. 74) is making a mountain out of a molehill.
Many more examples of Woodmorappe's (1999) misuse of the literature could be cited. Although a few of the dates mentioned in his book are significantly anomalous (e.g., Beakhouse et al., 1988), most of them are taken out of context. Frequently, Woodmorappe (1999) unjustifiably omits critical structural, geochemical, metamorphic, crystallographic, thin section, and other data from his citations that support and rationally demonstrate that the various dates really aren't mysterious anomalies that threaten to undermine the validity of radiometric dating (a few examples of the many references that Woodmorappe, 1999 distorts are: Pigage and Anderson, 1985; Beyth and Reischmann, 1996; Evans et al., 1995; Lawlor et al., 1999; Tucker et al., 1998; Aleinikoff et al., 1995; Corfu and Easton, 1995; Tucker and Gower, 1994; Van de Wel et al., 1998; Dallmeyer and Hibbard, 1984).
Certainly, for scientists that want errors below 1%, the precision and accuracy of any analytical result (whether it's a radiometric date or a benzene analysis of polluted groundwater) may not always comply with these strict requirements. Nevertheless, despite Woodmorappe's best attempts to hide the numbers in the above quotations, the revealed errors of less than 1-7% are far too trivial to serve the needs of young-Earth creationism.
Aleinikoff, J.N.; R.E. Zartman; M. Walter; D.W. Rankin; P.T. Lyttle and W.C. Burton, 1995, "U-Pb Ages of Metarhyolites of the Catoctin and Mount Rogers Formations, Central and Southern Appalachians: Evidence for Two Pulses of Iapetan Rifting," Am. J. of Sci., v. 295, p. 428-454.
Baksi, A.K.; K.A. Hoffman and M. McWilliams, 1993, "Testing the Accuracy of the Geomagnetic Polarity Time-scale (GPTS) at 2-5 Ma, Utilizing 40Ar/39Ar Incremental Heating Data on Whole-rock Basalts," Earth Planet. Sci. Lett., v. 118, p. 135-144.
Beakhouse, G.P.; R.H. McNutt and T.E. Krogh, 1988, "Comparative Rb-Sr and U-Pb Zircon Geochronology of Late- to Post-tectonic Plutons in the Winnipeg River Belt, Northwestern Ontario, Canada," Chem. Geol. (Isotope), v. 72, p. 337-351.
Beyth, M. and T. Reischmann, 1996, "The Age of the Quartz Monzodiorite, the Youngest Plutonic Intrusion in the Timna Igneous Complex," Israel J. Earth Sci., v. 45, p. 223-226.
Corfu, F. and R.M. Easton, 1995, "U-Pb Geochronology of the Mazinaw Terrane, an Imbricate Segment of the Central Metasedimentary Belt, Grenville Province, Ontario," Can. J. Earth Sci., v. 32, p. 959-976.
Dallmeyer, R.D. and J. Hibbard, 1984, "Geochronology of the Baie Verte Peninsula, Newfoundland: Implications for the Tectonic Evolution of the Humber and Dunnage Zones of the Appalachian Orogen," J. of Geol., v. 92, p. 489-512.
Evans, J.A.; I.L. Millar and S.R. Noble, "Hydration during Uplift is Recorded by Reset Rb-Sr Whole-rock Ages," J. Geol. Soc. London, v. 152, p. 209-212.
Evernden, J.F.; D.E. Savage; G.H. Curtis and G.T. James, 1964, "Potassium-argon Dates and the Cenozoic Mammalian Chronology of North America," Am. J. of Sci. v. 262, p. 145-198.
Kerr, R.A., 1995, "A Volcanic Crisis for Ancient Life?", Science, v. 270, Oct. 6, p. 27-28.
Lawlor, P.J.; F. Ortega-Gutierrez; K.L. Cameron; H. Ochoa-Camarillo; R. Lopez and D.E. Sampson, 1999, "U-Pb Geochronology, Geochemistry, and Provenance of the Grenvillian Huiznopala Gneiss of Eastern Mexico," Precambrian Res., v. 94, p. 73-99.
Muecke, G.K.; P.H. Reynolds; R.A. Macrae, and L.K. Nunez-Betelu, 1994, "40Ar/39Ar Geochronology of Late Cretaceous Volcanic Events in the Canadian Arctic Islands: Arctic Biotic Heterochroneity Revisited," in Abstracts of the Eighth International Conference on Geochronology, Cosmochronology, and Isotope Geology, Lanphere et al. (eds), U.S. Geologic Survey Circular 1107, p. 229.
Obradovich, J.D., 1984, "An Overview of the Measurement of Geologic Time and the Paradox of Geologic Time Scales," Stratigraphy, v. 1, p. 11-30.
Obradovich, J.D. and W.A. Cobban, 1975, "A Time-scale for the Late Cretaceous of the Western Interior of North America," in Cretaceous System in the Western Interior of North America, W.G.E. Caldwell (ed.), Geological Association of Canada, Special Paper 13, p. 31-54.
Peterson, F., 1994, "Sand Dunes, Sabkhas, Streams, and Shallow Seas: Jurassic Paleogeography in the Southern Part of the Western Interior Basin," in Mesozoic Systems of the Rocky Mountain Region, USA, M.V. Caputo et al. (eds), Society of Economic Paleontologists and Mineralogists.
Pigage, L.C. and R.G. Anderson, 1985, "The Anvil Plutonic Suite, Faro, Yukon Territory," Can. J. Earth Sci., v. 22, p. 1204-1216.
Prothero, D.R., 1994, The Eocene-Oligocene Transition, Columbia University Press, New York.
Swisher, C.C.; L. Dingus and R.F. Butler, 1993, "40Ar/39Ar Dating and Magnetostratigraphic Correlation of the Terrestrial Cretaceous-Paleogene Boundary and Puercan Mammal Age, Hell Creek - Tullock Formations, Eastern Montana," Can. J. Earth Sci., v. 30, p. 1981-1996.
Tucker, R.D.; L.D. Ashwal and E.K. Zinner, 1998, "Slow Cooling of Deep Crustal Granulites and Pb-Diffusion in Zircon," Proceed. GSA Annual Meeting, p. A-213.
Tucker, R.D. and C.F. Gower, 1994, "A U-Pb Geochronological Framework for the Pinware Terrane, Grenville Province, Southeast Labrador," J. of Geol., v. 102, p. 67-78.
Van de Wel, L.; J.M. Barton, Jr.; P.D. Kinny, 1998, "1.02 Ga Granite Magmatism in the Tati Granite-Greenstone Terrane of Botswana: Implications for Mineralization and Terrane Evolution," S. Afr. J. Geol., v. 101, n. 1, p. 67-72.
Woodmorappe, J., 1999, The Mythology of Modern Dating Methods, Institute for Creation Research, El Cajon, CA.
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