Not So Subjective Ar-Ar
Spectra and Not so Objective Dr.
Kevin R. Henke
Dr. Kevin R. Henke
The following material may be freely copied and distributed as long as the author is properly acknowledged
and the material is not altered, edited or sold.
HOW SUBJECTIVE ARE DEFINING PLATEAUS ON Ar-Ar SPECTRA?
40Ar-39Ar dating is extremely powerful and reliable (e.g., Hanes, 1991, p. 27; Lo and Yui, 1996, p. 14), and the shapes of 40Ar-39Ar spectra are frequently used to unravel the geologic histories of minerals and other samples (McDougall and Harrison, 1999, chapter 4). Not surprisingly, Woodmorappe (1999, p. 72-79) spends a lot of time arguing that the guidelines for identifying and interpreting plateaus on Ar-Ar spectra are 'subjective' and 'unreliable'. According to Woodmorappe's (1999, p. 72-79) mistaken beliefs, Ar-Ar spectra are so 'subjective' that it's easily possible to justify or reject the validity of any dates derived from the spectra.
Woodmorappe (1999, p. 79) quotes the following sections of Harrison (1990, p. 219, 227) to argue that the interpretation of 40Ar/39Ar spectra is not straightforward:
'For example, an early approach in assessing age spectrum results was to devise rules based on often recognized, but largely unexplained, vagaries (such as, "a hump-shaped spectrum means...") or invent what appear to be objective criteria for age assessments (such as, "a plateau contains five consecutive steps consisting of..."). Instead, multiple isochrous steps may reflect nothing more than experiment failure... As with all the subjective aspects in 40Ar/39Ar dating, common sense remains the most important test. The apparently widespread expectation that a system of rules can uniformly allow all samples to reveal straightforward age spectra or isochrons is counterproductive.'
However, what is the context of Harrison's (1990) statements?
'For example, an early approach in assessing age spectrum results was to devise rules based on often recognized, but largely unexplained, vagaries (such as, "a hump-shaped spectrum means...") or invent what appear to be objective criteria for age assessments (such as, "a plateau contains five consecutive steps consisting of..."). Instead, multiple isochrous steps may reflect nothing more than experiment failure by homogenizing an initially complex 40Ar distribution; consecutivity may be a poor criterion if diffusion effects cause reservoirs to release at different times; peculiar shapes of age spectra may mean nothing more than an incorrect choice of trapped Ar composition, or could reflect serious open-system conditions. I think of these rules as our Old Testament, reflecting a time when relatively little was understood about the response of minerals to 40Ar/39Ar analysis, but comfort could be taken from an orderly classification system.'
Harrison (1990) argues that in the early days general empirical rules were derived to interpret Ar-Ar spectra. Now, however, we have a better understanding of what produces Ar-Ar spectra, which allows us to have a more objective and thorough approach to spectra interpretation rather than just relying on general rules that may not work in every situation.
Harrison (1990, p. 219-220) also makes the following statements, which hardly serve Woodmorappe's crusade:
'The trend AWAY FROM SUBJECTIVE CRITERIA in interpretation, a tradition beginning with Turner (1968), reflects the PROGRESSIVE INCREASE IN OUR UNDERSTANDING of underlying mechanisms and SUCCESSFUL tests of quantitative interpretative models.' [my emphasis]
As with many natural phenomena, scientists now recognize that the processes that affect Ar-Ar spectra shapes are more complex than previously realized. However, at the same time, they also better understand these processes and are better able to provide confident interpretations (Harrison, 1990, p. 219-220; McDougall and Harrison, 1999, chapter 4).
Although there is no formal, universal standard to distinguish a plateau from a non-plateau on an Ar-Ar spectrum, McDougall and Harrison (1999, p. 111-112) states that scientists use a variety of statistically based guidelines to identify a plateau. A typical example cited by McDougall and Harrison (1999, p. 111) is Dallmeyer and Lecorche (1990), which states:
'A plateau is considered to be defined if the ages recorded by two or more contiguous gas fractions (with similar K/Ca ratios) each representing >4% of the total 39Ar evolved (and together consisting of >50% of the total quantity of 39Ar evolved) are mutually similar within a +/-1% intralaboratory uncertainty.'
Contrary to what Woodmorappe (1999, p. 72-79) would have us believe, the guidelines for DEFINING an Ar-Ar plateau are practical, generally reliable and very objective.
Once a plateau is defined, its meaning, along with the meaning of the rest of the spectrum, must be determined. The spectrum may or may not provide an obvious date. If a date is obtained, scientists should use other methods (e.g., Ar-Ar correlation diagrams, Sinton et al., 1998) to confirm its validity. As with ANY analytical method, the results should be verified.
INTERPRETING 'FLAT' SPECTRA
Flat Ar-Ar spectra generally indicate that an igneous or high-grade metamorphic sample has experienced simple closed system behavior since its formation (e.g., Harrison et al., 1985, p. 2462; McDougall and Harrison, 1999, p. 110). Not surprisingly, Woodmorappe (1999) is especially desperate to undermine the reliability of flat spectra interpretations because even one spectrum with a reliable date in excess of 10,000 years is fatal to his antiquated interpretations of Genesis.
Woodmorappe (1999, p. 76) quotes the following sentence from Hanes (1991, p. 38) to claim that flat 40Ar/39Ar spectra cannot be reliably interpreted:
'However, caution is required, as it is possible to obtain plateau dates that have no meaning.'
Once more, Woodmorappe (1999, p. 76) exaggerates the problems in the name of Genesis and makes avoidable problems sound insurmountable. Specifically, Hanes (1991, p. 38) is stating that false plateaus may result from excessive grinding during sample preparation or from improper 'in vacuo' heating of samples in the laboratory, both of which (as Hanes, 1991, p. 38 explains) may be readily avoided!
Woodmorappe (1999, p. 76) also quotes a sentence fragment from Gansecki et al. (1996, p. 91) out of context:
'...interpretation of release spectra can be ambiguous.'
The context of the fragment reads:
'The problem of xenocrystic contamination in radiometric dating of young volcanic rocks, particularly pyroclastic rocks, is well known. In recent years, the 40Ar/39Ar technique has enabled workers to ELIMINATE or at least MINIMIZE contamination and/or excess 40Ar by SEVERAL different methods. Step-heating has been useful in identifying the presence of excess 40Ar...[references omitted], although interpretation of release spectra can be ambiguous.' [my emphasis]
Contrary to Woodmorappe's (1999, p. 76) claims, Gansecki et al. (1996, p. 91) is NOT specifically referring to nice, flat plateaus, but to plateaus that result from excess argon in young volcanics, which are typically U-shaped or otherwise non-flat. Considering that Woodmorappe (1999, p. 76, etc.) does not want his readers to think that excess argon can be detected and its effects eliminated or minimized, it's not surprising that he omits the first part of Gansecki et al.'s (1996) sentence. By misquoting Hanes (1991) and Gansecki et al. (1996), exaggerating the problems in Ar-Ar dating and completely ignoring the successes, Woodmorappe (1999, p. 76) has only exposed his ultrafundamentalist religious biases and his general inability to properly, accurately and objectively summarize the radiometric literature.
By quoting the following brief statement from Connelly and Dallmeyer (1993, p. 351), Woodmorappe (1999, p. 75) argues that the meaning of 'flat' Ar-Ar spectra is ambiguous and depends on 'geological interpretations':
'Interpreting the geologic significance of the 40Ar/39Ar results depends upon the calibration of the Paleozoic time-scale...[references omitted].'
Connelly and Dallmeyer (1993, p. 351) concluded from mineral textures in their samples AND 40Ar-39Ar dating that the rocks of the Western Blue Ridge Mountains of the Appalachians, USA, experienced two metamorphic episodes (440 to 460 Ma [Ma = million years old] and 360 to 380 Ma). Because these episodes just happen to closely coincide with the Ordovician-Silurian and Devonian-Carboniferous boundaries, Connelly and Dallmeyer (1993, p. 351) simply state that whether the episodes are Ordovician, Silurian, Devonian, or Carboniferous depends on the details of what geologic time scale is used. Some geologic time scales define the boundaries between the periods at slightly different times than other time scales. In particular, the Ordovician-Silurian boundary usually varies between 438-446 Ma and the Devonian-Carboniferous boundary is typically between 352-368 Ma (e.g., Dalrymple, 1991, p. 60; 1999 Geologic Time Scale, GSA Website (Adobe Acrobat format (R) ); Harland, 1983, p. 397). The metamorphic events don't have to be compared to the geologic time scale, but most geologists would like to assign the episodes to periods and epochs, and not just to dates in millions of years.
Also, if Woodmorappe (1999, p. 75) wants to reject the 40Ar-39Ar dates in Connelly and Dallmeyer (1993), he still has to explain how multiple metamorphic mineral assemblages and their associated textures formed, and how rocks could go through multiple heating, cooling and deformation events in only a few thousand years. Without miracles, the conductivities and other properties of voluminous and deeply buried rocks are not suitable enough for multiple cycles of heating and cooling in only a few thousand years (Turner, 1981, p. 21-24, 78f; also see: 'Magma Cooling' in 'More Errors on "True.Origins": J. Sarfati's Support of Flood Geology', which exposes A. Snelling's and J. Woodmorappe's errors and insufficient statements on the related topic of magma cooling).
Woodmorappe (1999, p. 75) also quotes the following statement from Hanes (1991, p. 38-39):
'One could [Woodmorappe says can] conclude, therefore, that a plateau spectrum is generally a necessary, but not sufficient, indication that a mineral has not partially lost argon since it last passed through its closure temperature.'
By quoting this reference, Woodmorappe (1999, p. 75) argues that a 'flat spectrum' does not necessarily provide a 'true age' for a sample. Certainly, ALL analytical results, including Ar-Ar data and measurements on drinking water for dangerous concentrations of metals and bacteria, should be checked and verified. That is, scientists should duplicate an analysis or, in the case of Ar-Ar studies, perform additional analyses on other minerals. Also, in most cases, other independent tests can be performed to confirm the dates from flat or nearly flat spectra, such as Ar-Ar correlation (isochron) diagrams (e.g., Sinton et al., 1998; Baksi, 1999) or U-Pb dating (Wang et al., 1998). Contrary to Woodmorappe's (1999, p. 78-79, etc.) ignorant accusations, scientists are not stuck with 'uniformitarian guesswork', 'special pleadings', or 'groundless rationalizations' to justify their interpretations of Ar-Ar spectra.
Hanes (1991) provides a nice summary of the strengths and weaknesses of K-Ar and Ar-Ar dating, including useful advice and discussions of the problems associated with interpreting Ar-Ar spectra. Nevertheless, Woodmorappe (1999, p. 75) fails to mention the positive statements on K-Ar and Ar-Ar radiometric dating in Hanes (1991). As an example, Hanes (1991, p. 27) states:
'Since its inception some 40 years ago, the K-Ar age-dating method has been one of the most widely used geochronological tools. As potassium is the eighth most abundant element in the earth's crust, and thus occurs in numerous common igneous and metamorphic minerals, the K-Ar method CAN BE APPLIED TO A WIDE RANGE OF GEOLOGICAL PROBLEMS. Furthermore, since the decay of parent 40K to daughter 40Ar has a half-life of 1250 Ma, the method permits the PRECISE dating of rocks ranging in age from the formation of the solar system down to as young as a few thousand years. With the advent of the 40Ar/39Ar variant of K-Ar dating, the method has become INCREASINGLY VALUABLE for understanding the thermal histories of rocks.' [my emphasis]
While Woodmorappe (1999, p. 75) complains that geologists supposedly cannot find the 'True age' of a rock from a flat Ar-Ar spectrum, geologists recognize that rocks may have complex histories that involve several thermal events and that each event requires dating. A flat spectrum may represent an igneous event or when a particular mineral passed through its closing temperature after a metamorphic episode. Woodmorappe (1999, p. 75) simply fails to fully appreciate that high heating will release argon from minerals. When crystalline structures melt or are highly disrupted, the argon gas tends to escape!!
Typically, metamorphic and igneous rocks can be easily distinguished by their chemistries, textures and/or mineralogies. To be exact, there are laboratory-calibrated chemical and mineralogical methods for estimating the temperature and pressure conditions of igneous and metamorphic events (geothermobarometry, Turner, 1981, p. 127-144; Winkler, 1979, p. 250-253). Optical properties, mineral textures and cross-cutting relationships between different minerals are also useful in distinguishing igneous from metamorphic minerals, and different generations of metamorphic minerals from each other (e.g., Jacobs and Thomas, 1996, p. 972; Connelly and Dallmeyer, 1993, p. 351). Once metamorphic and relict igneous minerals are identified, they may be individually dated or separated into mineralogical groups and dated.
HOW SUBJECTIVE ARE INTERPRETATIONS OF 'STEPPED' AND OTHER NON-FLAT Ar-Ar PLATEAUS?
Woodmorappe (1999, p. 77, especially Figure 29) states that a variety of conflicting age interpretations may be obtained from stepped (non-flat) Ar-Ar spectra depending upon which steps are used in the calculations. According to Woodmorappe (1999, p. 73-79), biased scientists use subjective criteria to select the 'best step' to date the sample.
In reality, geologists recognize that non-flat Ar-Ar spectra may provide no meaningful dates. Obviously, if igneous rocks are later influenced by one or more metamorphic events, the crystallization and post-crystallization events may be too complex to yield samples that provide useable Ar-Ar spectra.
Woodmorappe (1999, p. 77) quotes Roddick et al. (1992, p. 176) and tries to argue that whether or not geologists accept the validity of steps on non-flat spectra depends on whether any of the associated dates correspond to their expected geological interpretations. That is, Woodmorappe (1999, p. 77) is accusing geochronologists of using their 'biased expectations' to 'subjectively' accept or reject any available steps and their dates from non-flat spectra. Roddick et al. (1992, p. 176) states:
'The young ages in the low temperature release [at 6 million years] could be interpreted to represent a recent re-heating event but there is no regional or local evidence for post-crystallization tectonism, thermal overprinting or metamorphism in the area. Consequently, the irregular spectra is [sic, are] believed to be caused by low-K alteration phases in the biotite.'
The sample in Roddick et al. (1992, p. 175-176) is a low potassium (4.5 wt%) biotite from a volcanic tuff from the Yukon. Although the biotite 'appeared' to be visibly free of alteration, the low potassium concentration and the possible detection of serpentine in the biotite with X-ray diffraction methods (Roddick et al., 1992, p. 175) suggest that the biotite is altered and NOT ideal for Ar-Ar or K-Ar dating. Nevertheless, sometimes geologists cannot find better samples.
Radiometric dates from nearby volcanics suggest that the tuff should have an age of about 95 Ma. The dates from the non-flat Ar-Ar spectrum varied from 6 to 124 Ma (Roddick et al., 1992, p. 175-176). Surprisingly, however, Roddick et al. (1992, p. 176) found that the integrated date for the irregular spectrum was 94.6 +/- 1.0 Ma. Furthermore, the age of the final step was 97.9 +/- 1.3 Ma, which is also fairly close to the dates of the neighboring volcanics. Nevertheless, Roddick et al. (1992, p. 176) correctly expressed caution about accepting the validity of the integrated or final step dates for the biotite sample. Roddick et al.'s (1992, p. 176) cautious approach refutes Woodmorappe's (1999, p. 77) suggestions that these authors readily accepted these Ar-Ar dates just because they happened to be consistent with the expected results.
As part of his crusade, Woodmorappe (1999, p. 77) also cites Sinton et al. (1998, p. 165) to further claim that 'different dates' may be obtained from stepped Ar-Ar patterns depending on how they are 'interpreted'. But, how 'different' are the Ar-Ar results in Sinton et al. (1998)? Do different 'interpretations' really lead to wildly different Ar-Ar dates as Woodmorappe (1999) would have us believe?
Sinton et al. (1998) dated several volcanics from the North Atlantic. Contrary to Woodmorappe's (1999, p. 77) accusations that interpretations of Ar-Ar spectra are subjective and arbitrary, Sinton et al. (1998) used well-established, conservative criteria to define the crystallization dates of the volcanics from Ar-Ar spectra and verified the dates with 36Ar/40Ar vs. 39Ar/40Ar correlation (isochron) diagrams. Specifically, Sinton et al. (1998, p. 165) states:
'We define a reliable age, that is, one that is representative of the crystallization age, based on the conservative criteria of Pringle (1993): (1) a well-defined age spectrum plateau of at least three concordant consecutive steps that represents at least of 50% of the total 39Ar released; (2) a concordant isochron age in which the F-distribution statistic SUMS/(N-2) is below the cut-off value at the 95% confidence level; (3) the 40Ar/39Ar intercept is statistically indistinguishable (within 1 sigma) from the atmospheric value 295.5.'
This approach is hardly arbitrary and subjective.
Most of Sinton et al.'s samples were visibly altered and, not surprisingly, many of them failed to meet the quality criteria, which are required to define an Ar-Ar crystallization date (Sinton et al., 1998, p. 164-165). However, the samples that passed the criteria produced well-defined plateaus and very consistent correlation diagrams. The dates ranged from 54.3 +/- 0.5 Ma to 62.1 +/- 0.6 Ma, depending on location. For example, a dacite from the Darwin Complex provided an Ar-Ar plateau date of 55.9 +/- 0.3 Ma and a consistent correlation diagram date of 54.9 +/- 1.0 Ma. The 40Ar/36Ar intercept value from the correlation diagram shows the slight presence of excess argon (that is, the 40Ar/39Ar value is 389.6 +/- 2.7 compared with the atmospheric value of 295.5, Sinton et al., 1998, p. 164).
Sinton et al. (1998, p. 164-166) also analyzed two samples from the Voring Plateau (offshore Norway), which were especially altered and did not produce absolutely flat plateaus. Although each Ar-Ar spectra consisted of two plateaus, the dates for the plateaus were not radically different from each other or the correlation diagram results. Specifically, the tuff glass Voring sample had plateau ages of 56.2 +/- 0.8 and 54.3 +/- 0.5 Ma with a correlation diagram date of 54.3 +/- 0.5 Ma. The feldspar Voring sample contained potassium-poor plagioclase. Plateau ages for the plagioclase were 57.9 +/- 1.0 and 56.4 +/- 0.7 Ma with a correlation diagram date of 55.6 +/- 2.0 Ma (Sinton et al., 1998, p. 164-165). Dating altered samples is not easy, but Sinton et al.'s approach is not arbitrary and open to diverse interpretations as Woodmorappe (1999, p. 77) would have us believe.
In another attempt to demonstrate the 'subjectivity' of interpreting plateau spectra, Woodmorappe (1999, p. 77) quotes the following statement from Lamb and Cox (1998, p. 527):
'The disturbed spectrum of sample P35B...[reference to figure omitted] MAY be further evidence of a thermal overprint but because the majority of the steps yield the same age, WE FEEL CONFIDENT in the Late Devonian date.' [Woodmorappe's emphasis]
Woodmorappe (1999, p. 77) emphasizes Lamb and Cox's words 'may' and 'we feel confident' to stress that the authors are being 'subjective' about interpreting their Ar-Ar spectrum. However, because the spectrum is clearly disturbed, its interpretation is not straightforward and the quotation clearly indicates that Lamb and Cox (1998, p. 527) recognize that multiple interpretations are possible with this sample. Unlike dogmatic YECs, scientists are not afraid to admit their reservations about their data. By using 'may' and 'we feel confident', Lamb and Cox (1998, p. 527) are just being honest and cautious.
Lamb and Cox (1998) dated some Mongolian copper deposits whose ages are poorly known. In particular, sample P35B is an altered porphyry (Lamb and Cox, 1998, p. 526). The porphyry contains post-crystallization minerals, including the copper ore mineral, chalcopyrite. Because the porphyry contains textural and mineralogical evidence of both the original crystallization and later alteration events, we would expect both the original crystallization event and the subsequent alteration events to affect the radiometric dating results. From sample P35, sericite (an alteration mineral) was deliberately dated (Lamb and Cox, 1998, p. 526). The Ar-Ar isochron age of the sample was 367.2 +/- 3.8 Ma, whereas the 40Ar/39Ar date was a relatively poor 237.3 +/- 41.2 Ma (note the high uncertainty!).
Lamb and Cox (1998, p. 527) clearly recognize that further field and laboratory studies are required to verify these Ar-Ar dates because many of the samples are so obviously altered and the geology of many of the Mongolian field sites has not been adequately explored. Furthermore, the mean squares of weighted deviates (MSWD values) for the isochrons are quite high, 1.64 to 69.71 (Lamb and Cox, 1998, p. 526). Of course, Woodmorappe (1999, p. 77) emphasizes the uncertainties in Lamb and Cox (1998) without telling his readers about the altered conditions of the Mongolian samples.
Based on the following quotation from Fitch and Miller (1983, p. 506), Woodmorappe (1999, p. 77) argues that interpreting a 'staircase'-shaped spectrum is subjective:
'In certain rare, favourable circumstances argon-40/argon-39 age spectrum analysis can be used to help resolve these discrepantly TOO HIGH apparent ages...[several references omitted].' [Fitch and Miller's emphasis]
According to Woodmorappe (1999, p. 77), geologists may simply select whatever step(s) give a date that they like or if the spectrum fails to provide a useful date, the quality of the sample is blamed.
Once more, Woodmorappe (1999, p. 77) fails to provide the proper context for the Fitch and Miller (1983, p. 506) quotation. The full context is:
'Potassium-argon age determinations can be wildly discrepant when the samples selected for dating contain significant amounts of extraneous radiogenic argon...[references omitted, including two references by Woodmorappe's foe, Dalrymple]. In certain rare, favourable circumstances argon-40/argon-39 age spectrum analysis can be used to help resolve these discrepantly TOO HIGH [Fitch and Miller's emphasis] apparent ages...[several references omitted] in the more commonly encountered, less favourable circumstances, it is AT LEAST POSSIBLE for the severe disturbance of the argon-40/argon-39 age spectra to be used to demonstrate the PRESENCE AND EXTENT of an extraneous argon problem. Conversely, the absence of disturbance in age spectra, along with concordance between individual age spectra and conventional K-Ar "spot" dates, can be used to provide CONFIDENCE in the geological ACCURACY of ANY particular K-Ar date...[reference omitted] and is EQUALLY IMPORTANT.' [unless otherwise noted, my emphasis]
Interestingly and contrary to what Woodmorappe (1999, p. 75-77) wants us to believe, this quotation confirms that Ar-Ar spectra may be used to detect the presence of extraneous argon and when flat spectra are present, they may confirm the accuracy of corresponding K-Ar results.
As usual, Woodmorappe (1999, p. 77) ignores the positive results that Fitch and Miller (1983) obtained by using Ar-Ar to date kimberlite pipes from the De Beers Mine of South Africa. In particular, Fitch and Miller (1983, p. 505) state:
'The kimberlite pipe at De Beers Mine, Kimberley is a COMPLEX, multiple structure. Three CONCORDANT argon-40/argon-39 age spectra have been obtained from samples from the 720 m level in the East Peripheral kimberlite. Each spectrum is dominated by a major plateau-feature between 84 and 89 Ma and NONE shows significant evidence of either excess argon or argon loss discrepancy.' [my emphasis]
Woodmorappe (1999, p. 77) also accuses Nielson et al. (1990) of simply selecting whatever ages from a 'staircase' spectrum pattern that best suits their needs for dating the Peach Springs Tuff. To support his accusations, Woodmorappe (1999, p. 77) quotes the following selections from Nielson et al. (1990, p. 577):
'The spectra that climb to older ages throughout incremental Ar releases are similar to those exhibited by samples that have largely outgassed during a thermal event later than the initial crystallization of the rock...[reference omitted]. This interpretation would mean that the Peach Springs Tuff is older than 27 Ma, the apparent age of the oldest increment for any of the samples. However... these data preclude such an old age for the ash flow unit... We suspect that the discordant age spectra are the result of a two-component K-feldspar mixture: an endogenous K-feldspar and an older disturbed K-feldspar, which were indistinguishable in a hand-picked analytical sample of apparently clear and clean grains.'
As seen by the frequent use of ellipses, Woodmorappe (1999, p. 77) has omitted a lot of material from the above quotation. When we look at the quotation in context, we see that Nielson et al. (1990, p. 577) state that there are several possible explanations for the discordant spectra, but there are sound stratigraphic and radiometric reasons for believing that the tuff is less than 19 Ma:
'There are SEVERAL plausible explanations for incremental release spectra that characterize the mineral separates from bulk tuff samples... [references to table and figure excluded] These explanations include loss of 40Ar, retention of extraneous 40Ar, and contamination by older material. The spectra that climb to older ages throughout incremental Ar releases are similar to those exhibited by samples that have largely outgassed during a thermal event later than the initial crystallization of the rock...[reference omitted]. This interpretation would mean that the Peach Springs Tuff is older than 27 Ma, the apparent age of the oldest increment for any of the samples. However, in the central Mojave Desert and the Colorado River valley the Peach Springs Tuff overlies rocks with ages as young as 19.1 Ma...[references omitted] these data preclude such an old age for the ash flow unit. The age of the Peach Springs Tuff reported here ACCORDS WELL with its stratigraphic position relative to other dated rocks in these Miocene sections. [new paragraph] We suspect that the discordant age spectra are the result of a two-component K-feldspar mixture: an endogenous K-feldspar and an older disturbed K-feldspar, which were indistinguishable in a hand-picked analytical sample of apparently clear and clean grains.' [my emphasis]
Earlier K-Ar dates of the tuff from 17 different locations ranged from 16.2 to 20.5 Ma (Nielson et al., 1990, p. 571, 573). Nielson et al. (1990) dated samples of the tuff with Ar-Ar to better define its age. Nielson et al. (1990, p. 572) summarize their study:
'Four separates, three of sanidine and one biotite, were chosen for dating by the 40Ar/39Ar incremental heating method. Concordant K-Ar ages had been obtained for one biotite-sanidine pair (sample M80-BR for the Bristol Mountains... [reference to tables omitted]). Of the other two sanidine separates, one from the Mohave Mountains of Arizona (P81-MH...[reference to table omitted]) was dated by K-Ar at 18.0 Ma and the other sample, collected east of Kingman, Arizona (JP83-I40...[reference to table omitted]) never had been dated. The 40Ar/39Ar spectra were discordant and indicated possible lithic [xenolithic] contamination.'
Because the earlier samples were likely contaminated with xenocrysts or xenoliths, pumice (which appeared to be free of xenoliths) was collected from an outcrop of the Peach Springs Tuff at Kingman, Arizona (Nielson et al., 1990, p. 572). Sanidines were separated from the pumice and dated.
From the previously studied samples, the biotite and two of the sanidine separates produced discordant Ar-Ar spectra with step ages as high as 27 million years (Nielson et al., 1990, p. 571). Ar-Ar step analyses of the sanidines from the Kingman samples, however, provided essentially concordant spectra with dates of 18.52 +/- 0.33 and 18.26 +/- 0.39 Ma. Corresponding isotope correlation diagrams of the samples yielded consistent results of 18.60 +/- 0.47 and 18.33 +/- 0.33 Ma (Nielson et al., 1990, p. 576). Laser fusion measurements yielded a mean date of 18.51 +/- 0.10 Ma (Nielson et al., 1990, p. 571, 576). Of course, by only quoting parts of Nielson et al. (1990, p. 577), Woodmorappe (1999, p. 77) emphasizes the less precise results from the previously studied mineral separates and ignores the much better Ar-Ar results involving the Kingman, Arizona samples, which had been examined for xenoliths.
While YECs might argue that the presence of xenocrystic or xenolithic contamination was just 'made up' to 'explain away' some of the old dates for the tuff, Nielson et al. (1990, p. 577) says otherwise:
Field observations of the Peach Springs Tuff at MANY localities indicate that older (Proterozoic to Mesozoic) lithic and xenocrystic contamination is WIDESPREAD in the unit. [my emphasis]
Woodmorappe (1999, p. 78) also cites Bingen et al. (1998, p. 165-168) to emphasize that a variety of mineralogical properties and laboratory procedures may produce complex Ar-Ar spectra from amphiboles or other metamorphic and igneous minerals. However, while Woodmorappe (1999, p. 78) wants us to believe that these spectra cannot be reliably interpreted, under 'Interpretation of Spectra', Bingen et al. (1998, p.164-165) says otherwise:
'Regional variations of the cooling process can be evaluated by comparing a specific geochronometer at different localities, while the rate of cooling can be estimated by the use of several geochronometers with different closure temperatures. Such an approach allows terranes with variable uplift histories to be identified, these terranes being usually separated by tectonic boundaries. It has been SUCCESSFULLY used to unravel the cooling histories in MANY complex orogenic belts.' [my emphasis]
In another attempt to undermine the reliability and consistency of Ar-Ar spectra interpretations, Woodmorappe (1999, p. 78) quotes this section from Bingen et al. (1998, p. 168):
'Although hand-picking was carefully performed, differences in ages and shape of spectra from different aliquots of some samples were observed; they could be related to inhomogeneity at sub-sampling level.'
Nevertheless, Bingen et al. (1998, p. 168) conclude:
'For most fractions, the GOOD alignment of points on the inverse isotope correlation plot and the concordance between the Ca/K ratios derived from the 40Ar/39Ar heating experiments and those obtained by microprobe...[reference omitted] suggest that MOST spectra with a few steps provide REPRESENTATIVE hornblende ages.' [my emphasis]
Once more, Woodmorappe (1999, p. 78) emphasizes the problems and does not tell his readers that the problems may be minor or solvable.
Woodmorappe (1999, p. 79) also cites the following statement from 'Slettin' [sic, Sletten] and Onstott (1998, p. 140) and argues that the diffusion of argon in muscovites is 'so complex' that Ar-Ar spectra cannot be interpreted:
'The net effect of this process is to preclude the recovery of any 40Ar concentration gradient which may have formed in the muscovite during geologic processes.'
Rather than producing irresolvable contradictions and confusion as Woodmorappe (1999, p. 79) would have us believe, the research of Sletten and Onstott (1998, p. 123) indicates that the behavior of argon loss from muscovite can be explained and is related to the grain sizes of the muscovites and their crystalline properties. Furthermore, Sletten and Onstott's (1998, p. 140) studies indicate that through additional research it may be possible to use Ar-Ar dating to determine the geologic ages of different-sized particles in sedimentary rocks (e.g., detrital muscovite vs. authigenic illite).
To further support his accusations that Ar-Ar spectra are 'too complicated' to be successfully interpreted, Woodmorappe (1999, p. 77) quotes the following statement from Harrison et al. (1985, p. 2461), which deals with the results of an experimental study:
'40Ar/39Ar age-spectrum analysis of a hydrothermally treated biotite yields a complex release pattern casting doubt on the general usefulness of such measurements for geochronological purposes.'
Harrison et al. (1985) heated samples of a biotite to fairly high temperatures (600 to 750C) in the presence of water (hydrothermal treatment) to study the diffusion and loss of argon from the mineral. Unlike previous studies with hornblende and muscovite (Harrison et al., 1985, p. 2464-2465), the Ar-Ar spectrum of the TREATED biotite was complex and inconsistent with predicted results. They (1985, p. 2465) concluded that the spectrum was an artifact of vacuum extraction. Nevertheless, Harrison et al. (1985) are NOT saying that Ar-Ar dating of UNALTERED biotites with simple spectra is useless. For example, the hydrothermal studies in Harrison et al. (1985) were performed on biotites from the Cooma Granodiorite, Australia. Harrison et al. (1985, p. 2461-2462) state that the pre-treated biotite has a well-understood and simple geologic history, which involves a flat Ar-Ar plateau with an undisputed date of 398.8 +/- 2.5 Ma.
ARE Ar-Ar SPECTRA USED TO FABRICATE METAMORPHIC EVENTS?
In a total lack of decency, Woodmorappe (1999, p. 75) baselessly accuses geologists of making up metamorphic events to simply explain away Ar-Ar spectra that are too young. Obviously, unless there is confirming mineralogical, textural, or field evidence, geologists are reluctant (e.g., Roddick et al., 1992, p. 176) to invoke the existence of a metamorphic event on the basis of a single radiometric date.
At the same time, it's clear that Woodmorappe (1999, p. 75) has no interest in recognizing any mineralogical, chemical, textural or field evidence that supports radiometric results. Even when abundant and obvious metamorphic minerals are present, Woodmorappe (1999, p. 75) simply ignores this evidence and continues his libelous attacks on Ar-Ar and other dating methods. Specifically, while Woodmorappe (1999, p. 75) attacks the validity of Ar-Ar dates from Dallmeyer and Villeneuve (1987), Lo and Yui (1996), and West et al. (1995), he neglects to mention that each of these articles discusses samples that have obvious mineralogical, textural, structural and other evidence for one or more metamorphic events. Now, Woodmorappe (1999, p. 75) might accept the undeniable fact that orthogneisses and other metamorphosed igneous rocks exist, but he clearly refuses to recognize their authenticity whenever Ar-Ar spectra or other radiometric data confirm the existence of the metamorphic event(s) and even date them. As an example, Lo and Yui (1996) studied high-pressure glaucophane schists and omphacite-bearing rocks in Taiwan. Petrographic (microscope) studies indicated that the high-pressure metamorphic rocks also experienced a later greenschist facies (relatively low temperature, low pressure) metamorphic event (Lo and Yui, 1996, p. 24). Rather than demonstrate that 40Ar/39Ar dating is worthless, Lo and Yui (1996, p. 14) found that the method provided reasonable dates for BOTH metamorphic events (100-110 Ma for the blueschist metamorphism and about 11 Ma for the greenschist event). Lo and Yui (1996, p. 26) finally conclude:
'In summary, our 40Ar/39Ar dating analyses on the high-pressure rocks in Taiwan have provided some important results which are essential in revealing the geohistory of Tananao Basement Complex of Taiwan.'
Furthermore, they (1996, p. 14) state:
'It has been WIDELY APPRECIATED that the 40Ar/39Ar dating technique is a POWERFUL tool for thermochronological study of minerals in the blueschists that have undergone complex thermal histories...[numerous references omitted].' [my emphasis]
The contents of Lo and Yui (1996), like most of the articles that Woodmorappe cites, hardly contain good news for young-Earth creationism.
While Woodmorappe (1999, p. 75) suggests that Ar-Ar dating is inconsistent and chaotic, West et al. (1995) says otherwise. West et al. (1995) studied rocks in Maine that were known to have been metamorphosed during the Silurian. Rather than creating confusion, 40Ar-39Ar spectra from hornblendes along with the presence of plutons and extensive retrograde metamorphic textures indicate the presence of a second, lower-grade metamorphic event. This second event occurred during the Devonian (West et al., 1995, p. 1845). Again, there is overwhelming mineralogical, textural and structural evidence of complex metamorphic events, just as the radiometric results indicate.
Using field relationships and Ar-Ar radiometric dating, Dallmeyer and Villeneuve (1987) identified three separate tectonic events in the complex geologic history of Senegal, Africa. The events closely date the Pan African Phase I (which lasted from about 655 to 665 Ma), the Pan African Phase II (about 550 to 560 Ma), and a late Paleozoic event (about 270 to 280 Ma), which is related to the Appalachian Orogeny in North America via plate tectonics. Using the data, Dallmeyer and Villeneuve (1987, Figure 10, p. 609 and Figure 11, p. 610) present plate tectonic models to summarize the geologic history of the region. Of course, Woodmorappe (1999, p. 75) neglects to mention these positive and consistent results when he discusses this article.
Woodmorappe (1999, p. 76) proceeds to comb the literature to locate other real and imagined Ar-Ar dating failures, and improperly belittles the importance and value of the numerous successes. For example, Woodmorappe (1999, p. 76) accuses Kontak et al. (1998) of supposedly explaining away 'contradictory' Ar-Ar spectra by invoking 'unsubstantiated' cooling events that occurred at different times and different places in Nova Scotia. However, while Woodmorappe (1999, p. 76) wants to believe that the multiple heating-cooling (metamorphic) and deformation episodes in these Nova Scotia rocks are 'unsubstantiated', the mineral textures in these rocks clearly support the existence of these multiple events (Kontak et al., 1998, p. 749-751). Figure 3 in Kontak et al. (1998, p. 750) even shows photographs of the various overlapping deformation textures and metamorphic minerals! Furthermore, Figure 2 (Kontak et al., 1998, p. 749) shows how the metamorphic mineral, cordierite, in the Mooseland gold district samples was retrograded and deformed by these events.
In the radiometric portion of the study, Kontak et al. (1998) analyzed 15 whole-rock metamorphosed clays (argillites) from the Meguma gold deposits of Nova Scotia. The 40Ar/39Ar spectra gave excellent plateau dates that ranged from 379 to 403 Ma (Kontak et al, 1998, p. 746). Contrary to Woodmorappe's claims (1999, p. 76), most of the Ar-Ar results are very consistent with earlier radiometric results and field studies. For example, Kontak et al. (1998, p. 746) state:
'The results of this work compare WELL to previous whole-rock 40Ar/39Ar dating of the Meguma Group samples and WE CONCUR with previous workers that the range in dates (i.e., 380-410 Ma) reflects diachronous cooling of the area through the intracrystalline retention temperature for argon in mica (i.e., approx. 300-350C).'
Unexpectedly, however, Kontak et al. (1998, p. 746) found that the emplacement of the hydrothermal veins had not reset the Ar-Ar whole-rock metamorphic dates of the rocks surrounding the veins. They (1998, p. 746, 756) concluded that the veins had formed very quickly, too quickly to reach equilibrium and reset the Ar-Ar dates of the surrounding metamorphic rocks. Considering the grain sizes and other properties of the rocks, the hypothesis is very plausible. Additionally, Kontak et al. (1998, p. 756) roughly guessed the duration of vein emplacement at no more than about 300 years. One would think that Woodmorappe would welcome any evidence of rapid emplacement of mineral veins. On the other hand, that would require him to believe the Ar-Ar results. So, Woodmorappe (1999, p. 76) simply chooses to unjustly attack the work of Kontak et al. (1998) and offer no scientific (no miracles allowed) alternatives on how all of these rocks could ever have possibly undergone multiple metamorphic and deformational events in less than 10,000 years.
SCIENCE RARELY PROVIDES 'FINAL ANSWERS' AND OTHER ABSOLUTES
Woodmorappe (1999, p. 75, 78, etc.) complains that Ar-Ar dates do not provide 'final' answers and that geologists may 'backpeddle' and 'explain away' previously accepted Ar-Ar results once subsequent 'contradictory information' is obtained. However, as discussed below and elsewhere in this essay, Woodmorappe's (1999, p. 75, 78) 'examples' of 'contradictions' and 'inconsistencies' tend to be either trivial or taken out of context.
Woodmorappe (1999, p. 75) cites Wang et al. (1998, p. 332-334) as a supposed example of 'backpeddling' and 'special pleading' on the meaning of some Ar-Ar dates. Wang et al. (1998, p. 332-334) reinterpreted the Ar-Ar dates for some hornblendes from southwest Sweden. The previous dates consisted of two groups: 960 to 1030 Ma and around 930 Ma. Previously, the older dates were considered to correspond with crustal thickening. The younger circa 930 Ma event was believed to represent the cooling and uplifting of high-grade rocks (Wang et al., 1998, p. 332-333). As part of a more thorough study that used several different radiometric methods rather than just the Ar-Ar method (Wang et al., 1998, p. 320), the poorly resolved 960 to 1030 Ma range of dates is now considered to have possibly resulted from excess argon (Wang et al., 1998, p. 334). Woodmorappe (1999, p. 75) claims that the Ar-Ar dates were 'reinterpreted' when new 'contradictory' U-Pb results were obtained. In reality, however, the U-Pb zircon and titanite dates of 923 - 975 Ma SUPPORT the conclusion that the circa 930 Ma event is real and represents the cooling of high-grade rocks through 500C or the argon closing temperature of hornblende (Wang et al., 1998, p. 334). Nevertheless, these relatively minor changes in the chronology of these Swedish rocks really don't help to reduce the Earth's age to below 10,000 years. Furthermore, Wang et al. (1998, p. 319) conclude that the overall geochronological data for the high-grade metamorphic rocks of southwestern Sweden are GENERALLY ANALYTICALLY PRECISE. Once more, the radiometric results in this and other articles are not as dire as Woodmorappe (1999, p. 75) would want us to believe.
Woodmorappe (1999, p. 79) cites Baksi (1999, p. 13, 23) as another example 'retreating' on the reliability of K-Ar and Ar-Ar dating:
'Of ~35 such ages utilized for deriving plate motion models for the past 130 m.yr., at best only three...[dates given] in the Indian Ocean and one ... [date] for the Atlantic Ocean may be treated as crystallization ages... This includes two marginal plateau dates, whose utility is debatable.'
Notice that Woodmorappe (1999, p. 79) does not have the courage to list the values of the four crystallization dates. The complete sentence is:
'Of ~35 such ages utilized for deriving plate motion models for the past 130 m.yr., at best, only three (~32, ~50, and ~52 Ma) in the Indian Ocean and one (~65 Ma) for the Atlantic Ocean may be treated as crystallization ages.'
As usual, Woodmorappe (1999, p. 79) omits critical details from this article. Baksi (1999) evaluated a database consisting of K-Ar and Ar-Ar dates, most or all of which were obtained from whole rock analyses of ALTERED basalts. While some researchers consider the 35 dates in the one database to be reliable crystallization ages, Baksi (1999) applies strict quality criteria to the Ar-Ar spectra and clearly demonstrates that the majority of the 35 dates do not meet these very strict criteria. Although Woodmorappe (1999, p. 79) refuses to admit it, Baksi (1999) successfully demonstrates that goodness-of-fit parameters and other criteria may be used to distinguish questionable from reliable dates. Also, Woodmorappe (1999, p. 79) clearly wants his readers to believe that because Ar-Ar and K-Ar dating often do not yield highly accurate crystallization dates for very altered basalts that somehow Ar-Ar and K-Ar dating will not work on other specimens.
Unlike meteorites, Moon rocks, and unaltered plutonic rocks, obtaining original crystallization dates on highly altered rocks by using K-Ar and Ar-Ar methods are very difficult. The alteration typically results from interactions between seawater and the surface layers of basalts during and after eruption on the seafloor (Hyndman, 1985, p. 556-560, 171, 182-184). The alteration of the basalt is obvious and includes albites, chlorite, actinolite, epidote and other 'low-temperature' metamorphic-hydrothermal minerals (Hyndman, 1985, p. 556). Extensive alteration will certainly disrupt the crystalline structures of minerals, which prevent argon accumulation over time, or, in the case of post-eruption alterations, argon is released. Nevertheless, for some partially altered basalts and many unaltered basalts, Ar-Ar and K-Ar results can accurately date the eruption event (Baksi, 1999; McDougall and Harrison, 1999, p. 30-34). Because zircons are rare in basalts and other mafic rocks, K-Ar and Ar-Ar methods may be the only options for dating the solidification of these rocks.
In reality, there are few, if any, 'final answers' in science. 'Final answers' are for YEC fantasies and not science. No analytical method is so 'final' that it cannot be improved. Science always seeks to update, modify and even overthrow earlier conclusions. For example, errors of 5 to 10% may have been acceptable 40 years ago, but with modern radiometric methods, these errors are no longer desirable.
Also, few, if any, analytical methods are so powerful that no other methods are needed to decipher the history of an area or the characteristics of an individual sample. As with other scientific data, Ar-Ar results are usually supplemented with other dating methods, geochemical analyses, mineralogical examinations and/or field studies. The application of a variety of field and laboratory methods provides a more thorough summary of the characteristics and history of a sample.
Science can provide answers that deserve great confidence (such as the age of the Earth being 4.5 billion years). However, all of these answers have uncertainties and they may not be absolutely final. In other words, tomorrow geologists may use better methods, discover some errors in the previous analyses and conclude that the Earth is really 4.63 billion years old.
ALL DATA INTERPRETATION HAS A SUBJECTIVE COMPONENT
For decades, geochronologists have used a variety of statistical and other highly objective criteria to interpret Ar-Ar and other radiometric data. Nevertheless, ALL data interpretation has a subjective component. This is not only true for geochronology, but also for predicting the weight limit of a bridge, measuring pollutants in groundwater, performing X-ray diffraction analyses on a sediment, counting fish in the ocean, and mapping rock types. Specifically, no two people will contour elevations on a topographic map in exacting the same way.
Powder X-ray diffraction is often used to identify minerals in rocks and sediments. Computers may not always find peaks on X-ray diffraction diagrams that are obvious to the human eye, and some individuals may see 'peaks' that are really background noise. Nevertheless, there are general rules to guide and restrict the interpretations of Ar-Ar spectra, elevation contours, and X-ray diffraction diagrams. For Ar-Ar dating, these guidelines are clearly presented in Chapter 4 of McDougall and Harrison (1999). Because Woodmorappe (1999) is so concerned about the validity and objectivity of radiometric dates, from my laboratory experience, I hope that he is at least as concerned about the far less thorough and less accurate chemical and biological analyses that are used to verify that his drinking water and packaged food are free of harmful concentrations of toxins and bacteria.
SUBJECTIVITY AND NO FINAL ANSWERS IN THE BIBLE
Clearly, Ar-Ar and other radiometric dating methods are not as 'subjective' and 'unreliable' as Woodmorappe (1999) would have us believe. At the same time, the constant in-fighting among YECs and other fundamentalist Christians over infant baptism, the 'gifts' of the Holy Spirit, keeping a Sunday 'Sabbath', salvation by grace alone and countless other 'fundamental' issues clearly demonstrates that their biblical interpretations are far more 'plastic', subjective, and unreliable than anything in radiometric dating. Specifically, conservative Lutherans and conservative Baptists quote the same Bible and derive opposite conclusions about infant baptism. YECs Kofahl (1977) and Johnson (1986) cite Genesis 1:7 as 'evidence' of a 'vapor canopy' in the Earth's 'Pre-Flood' atmosphere, while YECs Brown (1995, p. 174-179) and Whitelaw (1983) read the same Bible and reject the existence of this 'canopy'. Matthew 7:3-5 clearly applies to YECs.
As shown by the numerous examples in Morris (1986), YECs will grasp at any extreme and ridiculous argument to 'prove' that the Bible is 'scientifically valid'. As Christian fundamentalists, YECs want us to believe that their Bible interpretations are 'objective', 'final', 'scientific', and 'reliable evidence of inspiration from God'. However, the absurdities of these fundamentalist interpretations become very obvious once they are reviewed in detail. For example, Morris (1986, p. 12) cites Genesis 22:17 to argue that 'scripture' correctly 'predicted' that the number of sand grains on the Earth roughly equals the number of stars in the Universe, or about 10 to the 26th power. I really question that we can know the number of stars in the Universe or the number of sand grains on the Earth's seashores within several orders of magnitude. Also, depending upon how 'sand grains' and 'seashores' are defined, the estimates will widely vary. Nevertheless, Morris' interpretation of Genesis 22:17 is an excellent example of a fundamentalist taking a piece of Genesis poetry too literally. A careful analysis shows that Morris' interpretation is inconsistent and flawed. Genesis 22:17 (King James' Version) states:
'That in blessing I will bless thee; and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore... '
Now, if Morris insists that the verse says: number of stars = number of sand grains on Earth's seashores = 10 to the 26th or some other huge number, then, to be fully consistent, the verse must also say: number of stars = number of sand grains on Earth's seashores = number of Abraham's descendants = 10 to the 26th or some other huge number.
So where are the trillions and trillions of descendants of Abraham? Unless they moved to other planets, they certainly are not living now and there's no evidence that the Earth ever had all of these people during the past few thousand years.
Elsewhere, Morris (1986, p. 28) argues for a literal interpretation of Jonah's fish story by quoting Matthew 12:40 (King James Version):
'For as Jonas was three days and three nights in the whale's belly; so shall the Son of Man be three days and three nights in the heart of the earth.'
Morris (1986, p. 28) argues that either Jonah was literally swallowed or Christ was mistaken. However, this is a false dilemma. Besides Morris' two alternatives, it is possible that 'Matthew' may have used a false quotation. Jesus may never have used Matthew 12:40. While Matthew 12:38-40, 16:4 and Luke 11:29-32 claim that Jesus' generation would be given the 'sign of Jonah' as a warning, Mark 8:11-12 says that there would be NO sign at all. That is, the reference to Jonah is absent from Mark 8:11-12.
The Gospel of Mark is generally considered to be older than Matthew and Luke. A lot of false statements may have been attributed to Jesus between the final version of Mark and the final Greek version of Matthew. Of course, fundamentalists don't want to admit this possibility.
The fundamentalists also fail to consider the full implications of taking Matthew 12:40 literally. Since Morris believes that a fish physically swallowed Jonah, does he believe that Jesus literally and bodily went 4000 miles into the core (literally, heart or center) of the Earth? How did Jesus physically fit into a core of dense nickel and iron? Miracles, no doubt. Why would Jesus want to be inside of an iron and nickel core for three days?
Only when we reject the scientific view of the Earth's interior and embrace the ancient Israelites' Sheol-view of the Earth, does Matthew 12:40 make sense. The ancients viewed the Earth's interior as full of caves haunted by demons (2 Peter 2:4) and as a literal place of the dead, rather than a dense and impermeable core of nickel and iron. Now, if Morris denies that Jesus literally went into the nickel-iron core of the Earth, then why should he believe in a literal bodily swallowing of Jonah? If Morris says that Jesus went there 'in the spirit', then why couldn't Jonah only have been swallowed 'in the spirit'? If Morris argues that the word 'center, core or heart' of the Earth should not be taken literally but only refers to an above ground tomb in Jerusalem, then why should we take the words of Jonah and the rest of the Bible literally? Why should we take the 'days' of Genesis literally? At this point it becomes obvious that the fundamentalists' view of the Bible is so subjective, erroneous, and flexible that it cannot be used to show that the biblical writers had any special insight into the true nature of the Earth's interior or the rest of the Universe. If Morris insists on reinterpreting the words of Matthew 12:40 in a selective non-literal manner, he only proves my point: when the Bible is wrong, fundamentalists redefine and twist verses to make them conform with science. If a Bible verse vaguely guesses or accidentally pokes at some scientific discovery, the Christian fundamentalists loudly proclaim it as evidence of 'divine inspiration' (e.g., Job 26:7; Is 40:22; Morris, 1986). If the science later changes and the Bible verse is no longer consistent with the new scientific discoveries, YECs can always 'reinterpret' the verse to make it consistent with the new science or just say that it's 'non-literal poetry'. As a specific example, 1 Chronicles 16:30; Isaiah 45:18 and Psalms 93:1, 96:10 and 104:5 were once used to argue for geocentricism; that is, the idea that the Earth is 'motionless' and located at the center of the Universe. Once heliocentricism replaced geocentricism after Copernicus and Galileo, most Jews and Christians no longer took the verses literally. That is, the verses became 'non-literal poetry'. To be exact, YEC Sarfati (1999, p. 100-101) openly scoffs at the idea that Psalm 93:1 should be taken literally to support geocentricism. For him, it's 'obvious' that the Psalms are non-literal poetry 'unlike' the 'history' of Genesis. While a geocentricist takes Psalm 93:1 literally, Sarfati (1999, p. 101) argues that the verse simply indicates that the Earth will not stray from its current orbit and rotation. Certainly, the Bible is more than plastic enough to accommodate both of these contradictory views!
While it's commendable that Sarfati (1999, p. 100-101) clearly admits that verses in the Psalms are not literal, it's too bad that he won't make the same admission with the talking snake and magical fruit in Genesis. Then, of course, Sarfati still has to respond to Isaiah 45:18 and 1 Chronicles 16:30, which also state that the Earth doesn't move. Is Isaiah and 1 Chronicles 'history', supposedly like Genesis, or 'non-literal poetry', like Psalms? Or, may be, all of these verses are nothing more than myths. Who decides the correct interpretation? Again, considering all of the Christian denominations and branches of Judaism, Bible interpretations are so numerous and subjective that no one can find any 'final answers'. Furthermore, it's all too obvious that if the verses about a talking snake and a motionless Earth were in the Koran or the Book of Mormon, the YECs would ridicule them and would never accept the verses as 'inspired'.
In conclusion, if a Bible verse vaguely guesses or accidentally pokes at some scientific discovery, the Christian fundamentalists loudly proclaim it as evidence of 'divine inspiration' (e.g., Job 26:7; Is 40:22; Morris, 1986). If the verses (e.g., the Earth has 'pillars' according to Job 9:6 and the 'immoveable Earth' of 1 Chronicles 16:30; Isaiah 45:18 and Psalms 93:1, 96:10 and 104:5) conflict with well-known, popular, and indisputable scientific facts, the verses are either ignored, brushed off as 'poetic' (Sarfati, 1999, p. 100-101) or YECs use their boundless imagination to remold the interpretations of the verses to conform to popular science (e.g., Morris, 1986). The new interpretations are then proclaimed as the 'perpetual Truth'. This 'tails, I win; heads, you lose' approach to interpreting the Bible gives the book a false air of inspiration and infallibility. Clearly, when YEC Bible interpretations are examined, we mostly see subjectivity and many wild interpretations that require a vivid imagination. In contrast, Ar-Ar and other radiometric dating methods are testable and infinitely more reliable and objective.
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