Potassium argon dating limitations


One of the most widely used is potassium–argon dating (K–Ar dating).Potassium-40 is a radioactive isotope of potassium that decays into argon-40.It cannot be used to accurately date a site on its own.



Cosmic radiation entering the earth’s atmosphere produces carbon-14, and plants take in carbon-14 as they fix carbon dioxide.The relatively short half-life of carbon-14, 5,730 years, makes the reliable only up to about 50,000 years.The technique often cannot pinpoint the date of an archeological site better than historic records, but is highly effective for precise dates when calibrated with other dating techniques such as tree-ring dating.For example, techniques based on isotopes with half lives in the thousands of years, such as Carbon-14, cannot be used to date materials that have ages on the order of billions of years, as the detectable amounts of the radioactive atoms and their decayed daughter isotopes will be too small to measure within the uncertainty of the instruments.