In the final report of ICR’s Radioisotopes and the Age of the Earth (RATE) project, Dr. Russell Humphreys reported that helium diffusion from zircons in borehole GT-2 at Fenton Hill, New Mexico, gave an age for the earth of 6,000 ± 2,000 years.1 This young age agrees with a literal reading of Scripture, but is at variance with the billions of years conventionally held. Gary Loechelt has been a frequent critic of Humphreys’ procedures for calculating the young age by helium diffusion.2 Humphreys has responded to Loechelt and other critics, demonstrating that their concerns were invalid and successfully defending his findings.
However, due to Loechelt’s persistent criticisms, Humphreys recently took a deeper look at one of the key papers on which his helium diffusion research was based, and he found some rather odd assumptions about local heating near the borehole.3 He concluded that some of the assumptions about the heating history of the borehole were made to avoid problems the authors of the paper (Harrison et al4) would otherwise have had with the diffusion of argon from the sample.
Humphreys decided to develop a second, independent method for estimating the age of the earth based on the diffusion of argon from feldspar in the same Fenton Hill borehole. The result was a slightly younger age for the earth than his earlier helium diffusion method.
A Brief Review of Diffusion
When radioactive isotopes decay in rock, various gases are produced as a byproduct. For example, uranium-238 in the rock decays to lead by alpha decay, producing alpha particles that combine with electrons to form helium. Potassium-40 decays directly to argon-40 by inverse beta decay and electron capture. The gases produced by radioactive decay are then free to move through the minerals in which they are imbedded and escape into the atmosphere….
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