Dating techniques in archaeology wiki
Chronometric methods include radiocarbon, potassium-argon, fission-track, and thermoluminescence.
The most commonly used chronometic method is radiocarbon analysis.
The earliest-known hominids in East Africa are often found in very specific stratigraphic contexts that have implications for their relative dating.
The majority of chronometric dating methods are radiometric, which means they involve measuring something related to radioactivity, for example radioactive decay.
They are called chronometric because they allow one to make a scientific estimate of the date of an object as expressed in years.
They do not, however, give "absolute" dates because they merely provide a statistical probability that a given date falls within a certain range of age expressed in years.
Radioactive carbon has a half-life of approximately 5,730 years plus or minus 40 years (1 standard deviation of error) and the theoretical absolute limit of this method is 80,000 years ago, although the practical limit is close to 50,000 years ago.Stratigraphic dating is based on the principle of depositional superposition of layers of sediments called strata.This principle presumes that the oldest layer of a stratigraphic sequence will be on the bottom and the most recent, or youngest, will be on the top.Because the pool of radioactive carbon in the atmosphere (a result of bombardment of nitrogen by neutrons from cosmic radiation) has not been constant through time, calibration curves based on dendrochronology (tree ring dating) and glacial ice cores, are now used to adjust radiocarbon years to calendrical years.
Relative dating methods allow one to determine if an object is earlier than, later than, or contemporary with some other object.
It does not, however, allow one to independently assign an accurate estimation of the age of an object as expressed in years.