Carbon dating methods accurate
The best gauge they have found is dendrochronology: the measurement of age by tree rings.Accurate tree ring records of age are available for a period extending 9,000 years into the past.Scientists at the Lamont-Doherty Geological Laboratory of Columbia University at Palisades, N.Y., reported today in the British journal Nature that some estimates of age based on carbon analyses were wrong by as much as 3,500 years.The Lamont-Doherty scientists conducted their analyses on samples of coral drilled from a reef off the island of Barbados.
Because it is radioactive, carbon 14 steadily decays into other substances.
But when a plant or animal dies, it can no longer accumulate fresh carbon 14, and the supply in the organism at the time of death is gradually depleted.
Since the rate of depletion has been accurately determined (half of any given amount of carbon 14 decays in 5,730 years), scientists can calculate the time elapsed since something died from its residual carbon 14.
This assumption is backed by numerous scientific studies and is relatively sound.
However, conditions may have been different in the past and could have influenced the rate of decay or formation of radioactive elements.
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