Until the 18th century, this question was principally in the hands of theologians, who based their calculations on biblical chronology. Bishop James Ussher, a 17th-century Irish cleric, for example, calculated that creation occurred in B. There were many other such estimates, but they invariably resulted in an Earth only a few thousand years old. By the late 18th century, some naturalists had begun to look closely at the ancient rocks of the Earth. They observed that every rock formation, no matter how ancient, appeared to be formed from still older rocks.
Radiometric dating is a process of identifying the age of a material based on known half-lives of decaying radioactive materials found in both organic and inorganic objects. Radiometric dating is often used to determine the age of rocks, bones, and ancient artifacts. In fact, radiometric dating can be used to determine the age of the Earth, 5. While not all objects have the same isotopes, both living and nonliving objects have some sort of decaying, radioactive isotope that can be used based on known decay rates. How does Radiometric Dating Work? An isotope of some sort is located and isolated within an object.
The radiometric evidence for a 4. The basic theory of radiometric dating is briefly reviewed. Since 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 this assumption was shown to be highly questionable.
Scientists estimate that the Earth is about 4. To understand how this process works, you need to know a little bit about atoms and isotopes. Often, any one atom has several different forms, called isotopes.