Rock dating geology
Metamorphic rocks are not always easy to date using radio-isotopes.
Results obtained usually signify the "date" of the metamorphism, but they may also yield the "age" of the original volcanic (or sedimentary) rock.
Furthermore, the seven samples from the small amphibolite unit near Clear Creek, which should all be the same age because they belong to the same metamorphosed basalt lava flow, yielded K-Ar model ages ranging from 1060.4±28 Ma to 2574.2±73 Ma.
This includes two samples only 0.84 meters apart that yielded K-Ar model ages of 1205.3±.2±73 Ma.
Yet the discordance patterns are consistent with past accelerated radioisotope decay, which would also render these "clocks" useless.