American physical chemist Willard Libby led a team of scientists in the post World War II era to develop a method that measures radiocarbon activity.He is credited to be the first scientist to suggest that the unstable carbon isotope called radiocarbon or carbon 14 might exist in living matter. Libby and his team of scientists were able to publish a paper summarizing the first detection of radiocarbon in an organic sample. Libby who first measured radiocarbon’s rate of decay and established 5568 years ± 30 years as the half-life. Libby was awarded the Nobel Prize in Chemistry in recognition of his efforts to develop radiocarbon dating.By dating rocks of known ages which give highly inflated ages, geologists have shown this method can’t give reliable absolute ages.Many geologists claim that radiometric “clocks” show rocks to be millions of years old.
Yet few people know how radiometric dating works or bother to ask what assumptions drive the conclusions. This figure wasn’t established by radiometric dating of the earth itself. Radiohalos shouldn’t exist, according to conventional wisdom!By dating these surrounding layers, they can figure out the youngest and oldest that the fossil might be; this is known as "bracketing" the age of the sedimentary layer in which the fossils occur.Teach your students about absolute dating: Determining age of rocks and fossils, a classroom activity for grades 9-12.So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.Scientists date igneous rock using elements that are slow to decay, such as uranium and potassium.