Finally, correlation between different isotopic dating methods may be required to confirm the age of a sample.
For example, the age of the Amitsoq gneisses from western Greenland was determined to be Accurate radiometric dating generally requires that the parent has a long enough half-life that it will be present in significant amounts at the time of measurement (except as described below under "Dating with short-lived extinct radionuclides"), the half-life of the parent is accurately known, and enough of the daughter product is produced to be accurately measured and distinguished from the initial amount of the daughter present in the material.
Radiometric dating is also used to date archaeological materials, including ancient artifacts.
Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied.
Precision is enhanced if measurements are taken on multiple samples from different locations of the rock body.
After an organism has been dead for 60,000 years, so little carbon-14 is left that accurate dating can not be established.
For most radioactive nuclides, the half-life depends solely on nuclear properties and is essentially a constant.
It is not affected by external factors such as temperature, pressure, chemical environment, or presence of a magnetic or electric field.
and is now the principal source of information about the absolute age of rocks and other geological features, including the age of fossilized life forms or the age of the Earth itself, and can also be used to date a wide range of natural and man-made materials.
Together with stratigraphic principles, radiometric dating methods are used in geochronology to establish the geologic time scale.
Among the best-known techniques are radiocarbon dating, potassium–argon dating and uranium–lead dating.