Another Study Undermines Woodmorappe's Crapshoot
Kevin R. Henke, Ph.D.
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Young-Earth creationist (YEC) John Woodmorappe (1999, p. 51-52, 85, 87-92, 95, etc.) has proposed that radiometric dates are simply products of "chance"; that is, they are "meaningless numbers" generated by analytical laboratories. According to Woodmorappe (1999, p. 16, 51-54, 82, etc.), after receiving these "meaningless" results, geologists usually only publish those dates that happen to correspond to their "preconceived expectations" or that can be somehow "rationalized away". Woodmorappe (1999, p. 87-92, 95, etc.) even argues that the numerous studies in the literature with consistent radiometric dates can also be "explained away" by "chance". These consistent results include countless samples that have been confirmed with two or more radiometric methods, fossil data, astronomical evidence, and/or paleomagnetic results (as examples: Baadsgaard et al., 1993; Baadsgaard et al., 1988; Queen et al., 1996; Montanari et al., 1985; Foster et al., 1989; Harland et al., 1990; Renne et al., 1998, p. 121-122; Hilgen et al., 1997, p. 2043; etc.). At the same time, Woodmorappe (1999, p. 16) resists the idea of accusing geologists of being liars and deliberately filling journals with fabricated numbers.
Statistical and economic studies of data from Baadsgaard et al. (1993), for example, clearly refute Woodmorappe's claims for a radiometric "crapshoot". Why would any intelligent scientist throw away thousands of dollars on radiometric methods if Woodmorappe's crapshoot is correct? Why does Woodmorappe (1999, p. 16, etc.) refuse to realize that scientists would quickly reject any analytical method (as they did with platinum electrodes for measuring Eh; Drever, 1997, p. 136) that generates inconsistent numbers even when duplicates and standards are run? How dumb does Woodmorappe think we are? Woodmorappe's accusations are so absurd that even simple statistical evaluations of the sloppy radiometric results from his YEC allies refute his claims. Radiometric dates simply are not products of "chance". Even leading YECs are now convinced that extensive radiometric decay has occurred in geologic materials.
Seidemann (1988), an article that supports the validity of K-Ar and Ar-Ar dating, also contains information that clearly refutes Woodmorappe's accusations of a radiometric "crapshoot". Woodmorappe (1999, p. 19) mentions that Seidemann (1988) obtained a broad range of dates. According to Woodmorappe (1999, p. 19), Seidemann "blamed" the imprecision on excess argon. Using K-Ar, Seidemann (1988) dated basalt samples from the early Jurassic Talcott and Hampton volcanic flows. The samples were collected from 15 locations in the Hartford Basin of Connecticut, USA. An early Jurassic age for the flows is supported by index fossils in associated sedimentary rocks (Seidemann, 1988, p. 37-38; Figure 2, p. 38).
As usual, Woodmorappe (1999) leaves out some critical information from Seidemann (1988) that actually refutes his crapshoot. Specifically, Seidemann (1988) deliberately dated a variety of unaltered and altered samples to determine how the degree of alteration might affect their radiometric dates. That is, his samples included specimens that were fresh and considered suitable for radioactive dating and others that were obviously altered and fractured and would not normally be dated (Seidemann, 1988, p. 39). The K-Ar dates for the Hampton flow ranged from 102 +/- 4 to 959 +/- 154 (!) million years, although most dates were around 200 million years old. Not surprisingly, the Hampton samples with the oldest dates also had the most intense hydrothermal ("hot water") alteration and the lowest potassium (K) contents (Seidemann, 1988, p. 39). Hydrothermal processes are expected to leach out a lot of the potassium and convert many of the volcanic feldspars, pyroxenes and other igneous minerals into antigorite, calcite, sericite and/or other alteration products. (Note: Hyndman, 1985, p. 543-545, 548-560 has some discussions on the chemical and mineralogical changes that are associated with the hydrothermal alteration of basalts and other mafic rocks.)
The youngest date from the Hampton samples (102 +/- 4 million years) was obtained from a highly fractured sample. A brecciated specimen yielded another relatively young date of 169 +/- 5 million years (Seidemann, 1988, p. 39). Seidemann (1988, p. 39) reasonably argues that the young dates probably resulted from the loss of radiogenic argon during the fracturing and brecciation events.
While Woodmorappe (1999, p. 76, etc.) incorrectly claims that excess argon cannot be detected, the presence of even small amounts of excess argon in the Hampton samples are obvious from their Ar-Ar spectra and various chemical diagrams, such as 40Ar/gram vs. % K and K-Ar dates vs. % K (Seidemann, 1988, p. 38-39, 41 and Figures 3 and 4 on p. 41). In contrast, the Talcott flow was generally less altered and 6 out of the 7 dates provided an average of 187 +/- 8 (2 sigma standard deviations) million years old (Seidemann, 1988, p. 42). Also, Ar-Ar spectra and chemical diagrams did not detect excess argon in the six Talcott samples (Seidemann, 1988, p. 42). The seventh Talcott sample, on the other hand, was considerably more altered than the other six and provided a date of 167 +/- 7 million years (Seidemann, 1988, p. 42). Now, Woodmorappe might claim that it's possible that Seidemann (1988) deliberately fudged his data by throwing out very old or very young dates. However, it is clear from the text that Seidemann (1988) had no motive for excluding ANY of the radiometric dates that he obtained, whether they were much older or younger than the expected early Jurassic age. Considering the purpose of his study, Seidemann could NOT have thrown out any of the dates without being deliberately dishonest and undermining the goal of his study. So, Woodmorappe is forced to either accept the age distributions in Seidemann (1988) as being complete or he must make unsubstantiated accusations that Seidemann (1988) is deliberately dishonest. Again, if Woodmorappe's crapshoot was correct, inconsistent results (perhaps even negative or billion year old dates) should have been obtained even on the fresh samples. Because the dates are clearly affected by the degree of alteration, the dates simply cannot be dismissed as "products of chance".
REFERENCES
Baadsgaard, H.; J.F. Lerbekmo; and I. McDougall, 1988, "A Radiometric Age for the Cretaceous - Tertiary Boundary Based upon K-Ar, Rb-Sr, and U-Pb Ages of Bentonites from Alberta, Saskatchewan, and Montana", Can. J. Earth Sci., v. 25, p. 1088-1097.
Baadsgaard, H.; J.F. Lerberkmo; J.R. Wijbrans; C.C. Swisher III; and M. Fanning, 1993, "Multimethod Radiometric Age for a Bentonite near the Top of the Baculites reesidei Zone of Southwestern Saskatchewan (Campanian-Maastrichtian Stage Boundary?)", Can J. Earth Sci., v. 30, p. 769-775.
Drever, J.I., 1997, The Geochemistry of Natural Waters: Surface and Groundwater Environments, Prentice Hall, Upper Saddle River, NJ.
Forster, D.A.; T.M. Harrison and C.F. Miller, 1989, "Age, Inheritance, and Uplift History of the Old Woman-Piute Batholith, California and Implications for K-feldspar Age Spectra", J. of Geol., v. 97, p. 232-243.
Harland, W.B.; R.L. Armstrong; A.V. Cox; L.E. Craig; A.G. Smith and D.G. Smith, 1990, A Geologic Time Scale 1989, Cambridge University Press, Cambridge.
Hilgen, F.J.; W. Krijgsman and J.R. Wijbrans, 1997, "Direct Comparison of Astronomical and 40Ar/39Ar Ages of Ash Beds: Potential Implications for the Ages of Mineral Dating Standards", Geophys. Research Lett., v. 24, n. 16, p. 2043-2046.
Hyndman, D.W., 1985, Petrology of Igneous and Metamorphic Rocks, McGraw-Hill Publishing Co., New York.
Montanari, A.; R. Drake; D.M. Bice; W. Alvarez; G.H. Curtis; B.D. Turrin and D.J. DePaolo, 1985, "Radiometric Time Scale for the Upper Eocene and Oligocene Based on K/Ar and Rb/Sr Dating of Volcanic Biotites from the Pelagic Sequence of Gubbio, Italy", Geology, v. 13, Sept., p. 596-599.
Queen, M.; L.M. Heaman; J.A. Hanes; D.A. Archibald and E. Farrar, 1996, "40Ar/39Ar Phlogopite and U-Pb Perovskite Dating of Lamprophyre Dykes from the Eastern Lake Superior Region: Evidence for a 1.14 Ga Magmatic Precursor to Midcontinent Rift Volcanism", Can. J. Earth Sci., v. 33, p. 958-965.
Renne, P.R.; C.C. Swisher; A.L. Deino; D.B. Karner; T.L. Owens; and D.L. DePaolo, 1998, "Intercalibration of Standards, Absolute Ages and Uncertainties in 40Ar/39Ar Dating", Chemical Geology, v. 145, p. 117-152.
Seidemann, D.E., 1988, "The Hydrothermal Addition of Excess 40Ar to the Lava Flows from the Early Jurassic in the Hartford Basin (northeastern U.S.A.): Implications for the Time Scale", Chem. Geol., v. 72, p. 37-45.
Woodmorappe, J., 1999, The Mythology of Modern Dating Methods, Institute for Creation Research, El Cajon, CA.