Young-earth advocate Robert Gentry claims that the presence of polonium radiohalos in certain rocks demonstrates that they are "primordial rocks" created almost instantaneously (within about 3 minutes) on day one of a literal creation week only several thousand years ago (Gentry, 1986). However, mainstream workers as well as other creationists have shown that geologic evidence invalidates his main thesis, and that serious problems exist in his methods, logic, and interpretations. Among these are:
1. Gentry has failed to describe the precise geologic setting from which many of his samples were taken.
2 Some of Gentry's samples are known to have been taken from metamorphic rocks and pegmatite veins that are intruded into, or occur on top of, sedimentary rocks - sometimes even fossil-bearing rocks (Collins, 1997a, 1988a, 2000; Wakefield, 1988a, 1988b, 1990). Logically, such veins must be younger than the sedimentary layers, and therefore cannot be primordial "creation rocks" as Gentry claims. Gentry has tried to deny some of this evidence, but it is extensive and well documented, and acknowledged even by other creationists (DeYoung, 2006; Snelling, 2002, 2003; Wise, 1989).
3. Several credible alternate hypotheses have been advanced for the origin of the supposedly anomalous Po-halos, including erasure or modification of inner halos by Alpha radiation from other isotopes, migration of uranium-series elements through rocks by fluid migration or diffusion, and modification of halos during geologic metamorphism (Baillieul, 2005; Brawley, 2007; Collins, 1997a, 1988a; Collins and Collins, 2010). Gentry has disputed but not effectively refuted these explanations. Moreover, it is not necessary for mainstream scientists to demonstrate precisely how the halos form in order to refute Gentry's claims about "creation rocks." The geologic setting of many of samples alone does this. Moreover, the following considerations further undermine other assertions and assumptions by Gentry.
4. Difficulties can exist with halo identification, including coloration reversals due to saturation effects, attenuation of alpha particle ranges by the radioactive inclusion, dose dependence of halo radii, lack of adequate data on the relation between energy and distance in various mineral types, and the effects of crystal imperfections and chemical impurities (Dalrymple, 1985). Evidently it is virtually impossible to distinguish certain Po halos from Radon 222 halos (Brawley, 1997; Wakefield, 1990).
5. Radon (222 Rn) is a gas that can difuse into the smallest pores or cleavages in rocks or be incorporated into them during crystallization. As the radon decays, Po isotopes nucleate the biotite (and fluorite) crystals, and Po-halos are formed (Collins, 1988b; 1997, 2000) .
6. Thin sections of Po-halos show that they are often concentrated along fractures and cleavage planes, in rocks containing uranium or other radioactive elements, strongly suggesting a secondary source of the halos (Baillieul, 2005; Collins, 1997a).
7. Creationists who examined Po halos in diamonds similarly concluded that the halos can be explained by hydrothermal fluid transport. They further conclude that they formed after emplacement of their host kimberlite/lamproite pipes at or near the earth’s surface (Armitage and Snelling, 2009).
8. Despite Gentry's claims to the contrary, Po(210) halos in coal do not require a young-earth explanation (Collins, 1997b).
9. Even if Gentry could demonstrate that rocks containing Po-halos were created instantaneously, it would not demonstrate when the rocks were created. Instantaneous creation does not necessarily imply young age.
At times Gentry seems to deliberately obscure or minimize the evidence against his claims. In the introduction at his website he states, "Have you heard that, decades later, this evidence still stands unrefuted by the scientific community?" Gentry declares that if claims by critics that Po halos formed in ways other than he asserts, "they would have passed peer review and been published in the open scientific literature... or have themselves been experimentally falsified." Yet as he knows, a number of rigorous, peer-reviewed scientific papers refuting his claims and supporting alternate explanations of Po formation have been published (as cited herein). Ironically, many of Gentry's own claims have not been published in peer reviewed literature, and when they have, strong rebuttals followed by both mainstream and creationist workers. Gentry's home page also boldly declares: "Every question regarding the validity or implications of this polonium-halo evidence has been systematically dealt with, in our published reports and in various discussions with those holding differing views." However, if one examines the page linked to the term "reports" one finds that they concentrate almost entirely on the physics of radio halos, and none substantially address let alone refute the geologic-setting evidence fatal to his claims. Andrew Snelling, a creationist geologist with "Answers in Genesis," bluntly stated that it is "wrong for Gentry to go on denying and rejecting the many impeccable observational evidences..." Snelling (2002) . Likewise, in reviewing evidence that many of the halos occur in intrusive dikes, Brown et al(1988) state: "...it would be safe to say that the majority of halo-containing minerals are younger than the host rock and therefore do not represent primordial material."
Where Gentry briefly alludes to the problematic geologic evidence, he dismisses it as based on "uniformitarian assumptions" or suggests that God could have created complext features in rock instantaneously. However, even other creationists acknowledge that the evidence of intrusion and underlying fossil-bearing rocks does not depend on uniformitarian assumptions, and do invalidate his interpretations (Wise, 1989; Snelling, 2003, 2005, 2006; DeYoung, 2006; Walker, 2001). As to Gentry's suggestion about instantaneous creation of complext features (presumably even the fossils in surrounding rocks), such "appearance of age" arguments are reminiscent of pre-modern ideas that fossils might have been created directly by God to test humans -notions that even most creationists of today find far-fetched and unscientific (Snelling, 2003; Walker, 2001). Such arguments would also seem to imply a deceptive or mischievious God, and make it impossible to trust any empirical data. Furthermore, since Po-halos have been found in many different geologic strata from Precambrian through Mesozoic, Gentries reasoning would make a large portion of fossil-bearing rocks "primordial," which conflicts with not only extensive geologic evidence, but also virtually all young-earth/Flood models.
Gentry's website notes that he sent letters to ICR and AIG (two of the most prominent creationist groups), challenging them to produce "fossiliferous granites." However, the point of this was not clear, since ICR and AIG never claimed that the granites themselves contained fossils, but that fossiliferous rocks sourrounding the granites, and other evidence of intrusion, refutes the "creation rocks" interpretation (Snelling, 2002). Gentry's website also boasts that he sent letters to the National Accademy of Sciences, challenging them to refute his Po evidence. This too seems like a pointless exercise, since Gentry's claims have already been well refuted by mainstream scientists and fellow creationists alike. Moreover, the entire young-earth paradigm is undermined by mountains of evidence from geology, biology, paleontology, and other fields.
Gentry's claims also include serious logical errors. For example, he argues that unless scientists can artificially form a hand-held piece of granite, it demonstrates that God created granite by fiat. However, whether or not humans can duplicate a piece of granite has no logical bearing on whether God and/or natural processes did so in the past. Indeed, since there are many post-Phanerozoic granitic rocks, which are acknowledged by all to be non-primordial, clearly Gentry's reasoning is flawed. Moreover, although most diamonds are Pre-cambrian, humans already have created synthetic diamonds. By Gentry's logic, this implies (contrary to his own claims) that Pre-cambrian rocks are not primordial. Finally, Gentry's view of granites implies that they were all formed in one way (instantaneously by God) whereas there is abundant geologic evidence that various granites formed by at least several different processes (Collins, 1988a). Other problems and inconsistencies with Gentry's granite-manufacture challenge are discussed by Dalrymple (1985).
Gentry also has made bold claims against conventional Big Bang Cosmology which are disputed by Pitts (2004) and others. While that controversy is beyond the scope of this paper, it may be worth noting that his writtings on the matter suggest further reasoning deficicies, including a tendency to jump from scientific findings to tenuous theological speculations. For example, he writes that his BBC work "led to my discovery that the locally observed, spherically symmetric galactic redshift distribution is unique and hence that a universal Center exists nearby. I identify it as the location of God's eternal throne, as per Hebrews 8-10 and Revelation 20 (Gentry, 2004).
Although most major creationist groups seem to be abandoning Gentry's claims that Po halos imply primordial rocks, they are now trying to fit the same evidence into a Flood Geology scenario. Some suggest that the halos are evidence that uranium bearing minerals were incorporated into the host rock by a rapid geologic process (DeYoung, 2006; Snelling, 2003). However, the vast bulk of geologic evidence, including several independent radiometric dating methods, refutes the entire young-earth paradigm (MacRae, 2004; Neyman, 2012; Stassen, 2005; Wien; 2002; Wolf, 2012). Creationist proposals that radioactive decay rates may have been significantly higher in the past is lacking in any credible evidence, and contradicted by rigorous studies (Isaac, 2004). Even if it were true, it would not yield the sloping pattern of dates seen in rocks from lower to higher stratigraphic levels, if as most YECs claim, all rocks are only a few to several thousand years old. Furthermore, as demonstrated by Meert (2002), "Radioactive decay at a rate fast enough to permit a young earth would have produced enough heat to melt the earth."*
* At the 2004 RATE Conference in Denver, CO, creationis Donald DeYoung acknowledged that the accelerated decay proposal was challenged by these problems. He remarked, "Neither variations in pressure, temperature, electrical, or magnetic fields has been shown to significantly affect nuclear decay." "This probably involved some sort of change in the "nuclear binding force..." His conclusion: this "must involve Divine intervention." (Smith, 2007). However, this approach and the denials of Gentry, seem to beg the question: how can young-earth advocates on the one hand claim that the science is on their side, but when faced with major problems and contradictory evidence, deny it exists or wave it away by invoking ad-hoc miracles? When non-miracculous solutions are offerred, they often contradict other evidence. For example, in attempting to deal with the excess heat problem inherent in the "accelerated decay" proposal, Russell Humhpreys first invokes miracles to explain the changing of physical constants, then suggests that excess heat might be removed by a new interpretation of cosmic expansion, despite it too violating known principles of physics. After elucidating these problems, Morton and Murphy (2004) write: "...why does Humphreys insist on any naturalistic approach at all, given all the miracles he postulates? Why not simply remove the heat miraculously? For these reasons, we reject Humphreys's cooling mechanism: because it is wrong, it is ineffective, it is falsified by observational data, and it is theologically flawed."
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