The Sphinx is carved from the natural limestone of the Giza Plateau known as the Mokkatam Formation.An Eocene-period sea retreated 50 million years ago, leaving an embankment that became the north-northwest part of the Giza Plateau.Both laboratories use standard, best-practice procedures on state-of-the-art equipment.
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.
These are former sedimentary and volcanic strata that have been transformed by heat and pressure, possibly during the intense upheavals when the dry land was formed on Day 3 of Creation Week.
Among these metamorphosed volcanic strata are amphibolites, belonging to the Brahma Schist.
And the K-Ar model "ages" are so widely divergent from one another (ranging from 405.1±10 Ma to 2574.2±73 Ma), even from very closely spaced samples from the same outcrop of the same original lava flow, as to be useless for "dating" any event.