Radiometric dating wikipedia the encyclopedia Cairns sex chat
The decay of radioisotopes can be used not only to date material but also to time very slow processes, such as the evolution of the Earth's atmosphere.
The key is to measure an isotope that has had time to decay a measurable amount, but not so much as to only leave a trace remaining.Half-lives must therefore be known with great accuracy for precise dating and should range from about 10 years.In addition, there should be no loss or gain of parent or daughter isotope during the time the ‘radioactive clock’ is operating; if this condition is only partly satisfied, allowances must be made.Such raw ages can be calibrated to give calendar dates.One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites.
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Given isotopes are useful for dating over a range from a fraction of their half life to about four or five times their half life.