Radiometric dating and astronomical dating
See table 1 at the bottom for a list of the most common elements used for Radiometric dating and their corresponding half lives.Carbon 14 dating: Carbon 14 dating method measures the time since a living organism has died.Fourth, a specimen's contamination by carbon from surrounding soil, water, vegetation, and animal matter can seriously undermine accuracy of tests on a given sample.Fifth, the release of carbon dioxide from fossil fuel burning significantly dilutes carbon 14, and researchers have no accurate way to calibrate this dilution factor.Because polonium has a fleeting existence, the polonium radiohalos had to have formed within hours and days.However, the source of the polonium had to be the uranium which was also at the same time producing the uranium radiohalos.There are certain kinds of atoms in nature that are unstable and spontaneously change (decay) into other kinds of atoms.
Third, because carbon 14 forms from cosmic ray bombardment of nitrogen 14 (and decays back into nitrogen 14 through the release of beta particles, i.e., electrons) the effect of variations in cosmic radiation intensity (caused by altitude, depth below the earth's surface, and astronomical events) can be difficult to calibrate.
When the molten material hardens, argon (produced by later decays of potassium-40) is once again trapped.
In this way, formation of an igneous rock resets the potassium-argon clock.
They are the systematic differences in radioisotope age estimates for the same rock units, as explained in item two above, which can only be reconciled by grossly accelerated decay rates in the past.
There are co-existing uranium and polonium radiohalos in the same mineral grains in granites from around the world.For certain mineral crystals it was found the uranium-lead radioactive age estimate was 1.5 billion years, yet the helium leak age was only about 6,000 years.