In spite of this, the three different radioisotope methods give three very different ‘ages’—that is the ‘isochron discordance’ is pronounced. For example, if accelerated radioisotope decay occurred, then alpha-decaying radioisotopes would yield older isochron ‘ages’ than beta-decaying radioisotopes.
Figure 8 graphically illustrates how that, even when the calculated error margins are taken into account, the different radioisotope dating methods yield vastly different ‘ages’ that cannot be reconciled. This is exactly the pattern in the Brahma amphibolites in Grand Canyon (figure 8).
Furthermore, the seven samples from the small amphibolite unit near Clear Creek, which should be even closer in age because they belong to the same metamorphosed basalt lava flow, yielded K-Ar model ‘ages’ ranging from 1,060.4 ± 28 Ma to 2,574.2 ± 73 Ma (figure 6).
This includes two samples only 0.84 m (2 ft 9 in) apart that yielded K-Ar model ‘ages’ of 1,205.3 ± 31 and 2,574.2 ± 73 Ma.
For example, the calculated ‘age’ could be taken as the ‘date’ of metamorphism, or it could be the ‘age’ of the original volcanic (or sedimentary) rock, or something in between, or something else.
Both laboratories use standard, best-practice procedures on state-of-the-art equipment and routinely provide accurate and repeatable measurements of the required isotopes.It seems they are trying to avoid the inescapable conclusion that the radioisotope methods simply do not yield reliable ages. potassium-argon (K-Ar) ‘ages’ calculated for each of the 27 amphibolite samples from Grand Canyon ranged from 405.1 ± 10 Ma (million years) to 2,574.2 ± 73 Ma.That is a six-fold difference, for samples that should be of similar age.Many people, including many scientists, accept these dates as absolute truth.They believe that when different radio-dating methods are used on the same rocks, they will all yield the same age.Because the different radioisotope pairs are supposed to be dating the same geologic (rock formation) event, different ‘dates’ mean that the parent radioisotopes decayed at different rates over the same time period.