Zircon crystals radiometric dating
To have eroded during the last years they could not have been at great depths beneath the surface.
Figure 2 shows the diffusion rate data for the four lowest temperatures evaluated in that study, and EC. As a result, all of the argon in a volcanic rock sample is assumed to date from that time.
They never recognize the underlying unprovable assumptions on which the U-Th-Pb system is based. This entire scenario is based on inferences about what happened in the distant past, including an assumed naturalistic origin for the earth.
This is a theoretical calculation, and we can therefore determine that the half-life of U is 4. For more on this important work, please see Humphreys, R.
They confirmed that the Pb isotope composition in the full volume of these very tiny sub-microscopic clusters was the same as that obtained by the standard SIMS secondary ion mass spectrometry technique used to date the tiny spots elsewhere within this zircon grain.