Chronometric dating, also known as chronometry or absolute dating, is any archaeological dating method that gives a result in calendar years before the present time.
Chronometric techniques include radiometric dating and radio-carbon dating, which both determine the age of materials through the decay of their radioactive elements; dendrochronology, which dates events and environmental conditions by studying tree growth rings; fluorine testing, which dates bones by calculating their fluorine content; pollen analysis, which identifies the number and type of pollen in a sample to place it in the correct historical period; and thermoluminescence, which dates ceramic materials by measuring their stored energy.
Scientists first developed absolute dating techniques at the end of the 19th century.
It is not affected by external factors such as temperature, pressure, chemical environment, or presence of a magnetic or electric field.
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.
It is therefore essential to have as much information as possible about the material being dated and to check for possible signs of alteration.