Yet the RATE research has uncovered much evidence, including the patterns of these discordances between the "dates" from the different radioisotope systems, For example, if accelerated radioisotope decay occurred, then alpha-decaying radioisotopes would yield older isochron "ages" than beta-decaying radioisotopes, which is exactly the pattern in the Brahma amphibolites (see diagram above).Because the different radioisotopes are dating the same geologic event, to have produced different "dates" has to mean that the parent radioisotopes have decayed at different rates over the same time period.The computer program Isoplot was used to plot isochrons and calculate isochron ages from the other radioisotope analyses.The best isochron plots, where all the variation from the line of best fit to the data incorporates all the analytical errors, yielded an Rb-Sr isochron age of 1240±84 Ma, an Sm-Nd isochron age of 1655±40 Ma, and a Pb-Pb isochron age of 1883±53 Ma.
Results obtained usually signify the "date" of the metamorphism, but they may also yield the "age" of the original volcanic (or sedimentary) rock.
The "age" or "date" is calculated from the amount of the daughter isotope produced by radioactive decay of the parent isotope.
In Grand Canyon, the "date" of metamorphism of the basalt lavas to form these Brahma amphibolites has been determined as 1690-1710 Ma (million years ago), based on U-Pb dating of minerals in the overlying Vishnu Schist and underlying Rama Schist that formed during the metamorphism.
However, they are confirmation of the repeated failure of all the radioisotope "dating" methods to successfully date Grand Canyon rocks.
but tenuous "explanations" are given to account for the anomalous amounts of daughter products, and avoid the inescapable conclusion that the radioisotope methods simply do not yield reliable absolute ages.