Radioactive age dating
Since 1955 the estimate for the age of the Earth has been based on the assumption that certain meteorite lead isotope ratios are equivalent to the primordial lead isotope ratios on Earth.In 1972 this assumption was shown to be highly questionable.Despite this, the momentum gained in the two decades prior to 1972 has made 4.5 b.y.
For teaching and sharing purposes, readers are advised to supplement these historic articles with more up-to-date ones suggested in the Related Articles and Further Reading below.Radiometric dating, often called radioactive dating, is a technique used to determine the age of materials such as rocks.It is based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.Before 1955, ages for the Earth based on uranium/thorium/lead ratios were generally about a billion years younger than the currently popular 4.5 billion years. old Earth is reviewed and deficiencies of the uranium/lead method are discussed.The basic theory of radiometric dating is briefly reviewed.
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Radiometric dating, or radioactive dating as it is sometimes called, is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes.