Dating techniques in archaeology

Once the organism dies, the Carbon-14 begins to decay at an extremely predictable rate.

Radioactive carbon has a half-life of approximately 5,730 years which means that every 5,730 years, half of the carbon-14 will have decayed.

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.

They are called chronometric because they allow one to make a very accurate scientific estimate of the date of an object as expressed in years.This number is usually written as a range, with 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.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.Cultural seriations are based on typologies, in which artifacts that are numerous across a wide variety of sites and over time, like pottery or stone tools.If archaeologists know how pottery styles, glazes, and techniques have changed over time they can date sites based on the ratio of different kinds of pottery.

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