Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2006

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Claim CD015:

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Response:

1. Subsurface pressure and temperature conditions affect how quickly the helium diffuses out of zircons. D. R. Humphreys et al. selected a rock core sample from the Fenton Hill site, which Los Alamos National Laboratory evaluated in the 1970s for geothermal energy production. The area is within a few kilometers of the Valles Caldera, which has gone through several periods of faulting and volcanism. The rocks of the Fenton Hill core have been fractured, brecciated, and intruded by hydrothermal veins. Excess helium is present in the rocks of the Valles Caldera (Goff and Gardner 1994). The helium may have contaminated the gneiss that Humphreys et al. studied. In short, the entire region has had a very complex thermal history. Based on oil industry experience, it is essentially impossible to make accurate statements about the helium-diffusion history of such a system.
   
   
2. Scientific studies, especially those with radical implications, do not mean much until the results have been replicated by others. Many scientific claims have disappeared entirely when others could not get the same results. Confidence in this particular paper is reduced by certain points:
   • Most measurement errors and variabilities are not reported. Therefore, we do not know how accurate the results are.
   • Humphreys et al. claimed that they studied zircons and biotites from depths of 750 and 1,490 meters in the Jemez Granodiorite. However, Sasada (1989) showed that at those depths, the samples came from a gneiss, an entirely different rock type.
   • Because of math errors, the Q/Q₀ values (fraction of helium retained), used by Humphreys et al. to derive their dates, are too high.
   • Humphreys et al. (2003) failed properly to total their data in Appendix C, which means that they grossly underestimated the total amount of helium released by their 750-meter-deep zircons. The amount of helium in the zircons greatly exceeds the amount that would be expected from the radioactive decay of uranium over 1.5 billion years. The high helium concentration may be due to samples that were abnormally high in uranium and/or to the presence of excess helium.
   • Much is made of the fact that samples five and six retained the same amount of helium, even though the amounts are probably at the limit of what could be measured. The possibility of measurement error accounting for the results is never mentioned.
   • If one discounts sample five, which is likely at the limit of measurable precision, the conclusions of Humphreys et al. (2004) rest on just three samples. Such a small data set may be the basis for further research, but not for drawing firm conclusions.
   • Humphreys et al. (2003, note 9) referred to correcting "apparent typographical errors" in the raw data, casting suspicion on the validity of all the data.
   
   The helium results could easily be due to an aberrant sample. They could be an artifact of the experimental or collecting method (e.g., defects in the zircons caused by rapid cooling) or from just plain sloppiness. We cannot know for sure until others have looked at the issue, too.
   
   
3. Producing a billion years of radioactive decay in a "Creation week" or year-long flood would have produced a billion years worth of heat from radioactive decay as well. This would pretty much vaporize the earth. Since the earth apparently has not been vaporized recently, we can be confident that the accelerated decay did not occur. (Humphreys recognizes this "heat problem" but is currently unable to provide a solution.)
   
   
4. If helium concentrations stay high around the rocks, it is possible for helium to diffuse into voids and fractures in the zircons, or at least high helium pressures could reduce the rate at which helium diffuses out. Either of these scenarios would invalidate the helium diffusion calculations in Humphreys et al. (2003, 2004). Helium concentrations within the earth become high enough for commercial mining. The sample measured by Humphreys et al. came from an area that is probably helium enriched. Helium deposits are common in New Mexico, and excess helium has been found just a few miles from where the sample was taken (Goff and Gardner 1994). To test for the presence of excess helium in their zircons, Humphreys et al. should look for ³He.
   
   
5. Uranium does not decay directly to lead; rather, it proceeds through a series of multiple intermediate radioactive elements (Faure 1986, 284-287). It takes about ten half-lives of the longest lived intermediate to achieve secular equilibrium (i.e., each intermediate having the same activity). The uranium decay series contains elements with half-lives well over 10,000 years. If the decay rates changed suddenly, we would not expect the various elements to be in a secular equilibrium. Humphreys et al. should test for this in their zircons. Other uranium ores are at secular equilibrium, indicating a constant decay rate for at least the last two million years.

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