More accurate methods were developed using gas-proportional counters and liquid-scintillation counters.These C atom decays, it emits a beta-particle, which can be counted in a gas by the electrical pulse it generates.C, using samples of several grams of carbon-black powder.Unfortunately, in the 1950's, due to atmospheric nuclear testing, this method was subject to errors due to the absorption of nuclear contaminant.C atoms in the sample would greatly enhance the sensitivity, and some unsuccessful attempts were made in this direction using conventional mass spectrometry. This technique has allowed the measurement of radiocarbon in samples of much less than a milligram, or over a thousand times less material than is needed from the older counting methods.
The false radiometric ages of several million years are due to parentless argon, as described here, and were first reported in the literature some fifty years ago.
Example: The radioactive element carbon-14 has a half-life of 5750 years.
The percentage of carbon-14 present in the remains of plants and animals can be used to determine age.
Another role of isotopic geochemistry that is of great importance in geology is radiometric age dating. Beginning with studies in the 1950s, a much better chronology and record of Pleistocene climatic events have evolved through analyses of deep-sea sediments, particularly from the oxygen isotope record of the shells of microorganisms that lived in the oceans.
Many geologists claim that radiometric “clocks” show rocks to be millions of years old.