These included seven samples from a 150 meter long and 2 meter wide amphibolite body outcropping just upstream from the mouth of Clear Creek at river mile 84 (measured from Lees Ferry).
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.
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.
Both laboratories use standard, best-practice procedures on state-of-the-art equipment.
The model K-Ar ages for each of the samples ranged from 405.1±10 Ma to 2574.2±73 Ma.These were originally basalt lava flows several meters to tens of meters thick.