bill-i must admit that i did wonder if elements from vast ages ago [for sake of argument] could be retained in a recent lava flow.
but then i thought- how could you be sure when any rock formed,after all the dating could be miscalculated by former elements.
the recent rock formed from lava and was misdated.
so if we cant trust the dating of rock of known age of forming,why should we trust the dating of unknown age. sigh.
i suppose i could be missing something in the argument.