Radioisotope dating lab
Familiar to us as the black substance in charred wood, as diamonds, and the graphite in “lead” pencils, carbon comes in several forms, or isotopes.One rare form has atoms that are 14 times as heavy as hydrogen atoms: carbon-14, or C ratio gets smaller.These techniques are applied to igneous rocks, and are normally seen as giving the time since solidification.The isotope concentrations can be measured very accurately, but isotope concentrations are not dates.That is, they take up less than would be expected and so they test older than they really are.
Geologist John Woodmorappe, in his devastating critique of radioactive dating, points out that there are other large-scale trends in the rocks that have nothing to do with radioactive decay.However, even with such historical calibration, archaeologists do not regard C produced and therefore dating the system.The amount of cosmic rays reaching the Earth varies with the sun's activity, and with the Earth's passage through magnetic clouds as the solar system travels around the Milky Way galaxy.Since the flood was accompanied by much volcanism (see Noah's Flood…, How did animals get from the Ark to isolated places? ), fossils formed in the early post-flood period would give radiocarbon ages older than they really are.In summary, the carbon-14 method, when corrected for the effects of the flood, can give useful results, but needs to be applied carefully.
This also has to be corrected for. Second, the ratio of C in the atmosphere at that time to be estimated, and so partial calibration of the “clock” is possible.