Scientific dating methods list

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.Precision is enhanced if measurements are taken on multiple samples from different locations of the rock body.

This predictability allows the relative abundances of related nuclides to be used as a clock to measure the time from the incorporation of the original nuclides into a material to the present.

The basic equation of radiometric dating requires that neither the parent nuclide nor the daughter product can enter or leave the material after its formation.

Among the best-known techniques are radiocarbon dating, potassium–argon dating and uranium–lead dating.

By allowing the establishment of geological timescales, it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change.

For instance, carbon-14 has a half-life of 5,730 years.

After an organism has been dead for 60,000 years, so little carbon-14 is left that accurate dating cannot be established.

The procedures used to isolate and analyze the parent and daughter nuclides must be precise and accurate.

This normally involves isotope-ratio mass spectrometry. The precision of a dating method depends in part on the half-life of the radioactive isotope involved.

The only exceptions are nuclides that decay by the process of electron capture, such as beryllium-7, strontium-85, and zirconium-89, whose decay rate may be affected by local electron density.

For all other nuclides, the proportion of the original nuclide to its decay products changes in a predictable way as the original nuclide decays over time.

The temperature at which this happens is known as the closure temperature or blocking temperature and is specific to a particular material and isotopic system.

Tags: , ,