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The relatively short half-life of carbon-14, 5,730 years, makes dating 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.
In historical geology, the primary methods of absolute dating involve using the radioactive decay of elements trapped in rocks or minerals, including isotope systems from very young (radiocarbon dating with Radiometric dating is based on the known and constant rate of decay of radioactive isotopes into their radiogenic daughter isotopes.
Particular isotopes are suitable for different applications due to the types of atoms present in the mineral or other material and its approximate age.
Argon, a noble gas, is not commonly incorporated into such samples except when produced in situ through radioactive decay.
In archaeology, absolute dating is usually based on the physical, chemical, and life properties of the materials of artifacts, buildings, or other items that have been modified by humans and by historical associations with materials with known dates (coins and written history).
Carbon-14 moves up the food chain as animals eat plants and as predators eat other animals. It takes 5,730 years for half the carbon-14 to change to nitrogen; this is the half-life of carbon-14.
After another 5,730 years only one-quarter of the original carbon-14 will remain.
An additional problem with carbon-14 dates from archeological sites is known as the "old wood" problem.
It is possible, particularly in dry, desert climates, for organic materials such as from dead trees to remain in their natural state for hundreds of years before people use them as firewood or building materials, after which they become part of the archaeological record.