What is radioactive dating of fossils

Posted by / 28-Jan-2020 16:40

It is founded on unprovable assumptions such as 1) there has been no contamination and 2) the decay rate has remained constant.By dating rocks of known ages which give highly inflated ages, geologists have shown this method can’t give reliable absolute ages.Carbon-14, or radiocarbon, is a naturally occurring radioactive isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecules, which then oxidize to become carbon dioxide.Green plants absorb the carbon dioxide, so the population of carbon-14 molecules is continually replenished until the plant dies.Carbon-14 has a half-life of 5,730 ± 40 years, meaning that every 5,700 years or so the object loses half its carbon-14.

Carbon 14 with a half life of 5,700 years can only be used to date fossils of approximately 50,000 years. If 50% of pure uranium' is left in a sample the sample is assumed to be 4.5 billion years old.( This is assuming that the original sample was 100% uranium and no Uranium 238 has been eroded or lost in 4.5 billion years old.Most fossils are thought to be much older than 50,000 years. The fossilized remains have been mineralized where the original organic material has been replaced and turned into stones containing no carbon. If a fossil has only 25 % of the Uranium 238 the sample has an estimated age of 3.2 Billion years.This would be the estimated age of the earliest life or formation of fossils. Uranium 238 is only found in igneous or volcanic rocks. Because of the huge differences in the half lives of Carbon 14 and Uranium238 they cannot be used together.Many geologists claim that radiometric “clocks” show rocks to be millions of years old.However, to read any clock accurately we must know where the clock was set at the beginning.

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This technique is widely used on recent artifacts, but educators and students alike should note that this technique will not work on older fossils (like those of the dinosaurs alleged to be millions of years old).