Bishop James Ussher, a 17th-century Irish cleric, for example, calculated that creation occurred in 4004 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.
Radiocarbon dating is one kind of radiometric dating, used for determining the age of organic remains that are less than 50,000 years old.
For inorganic matter and for older materials, isotopes of other elements, such as potassium, uranium, and strontium, are used.
he question of the ages of the Earth and its rock formations and features has fascinated philosophers, theologians, and scientists for centuries, primarily because the answers put our lives in temporal perspective.
Until the 18th century, this question was principally in the hands of theologians, who based their calculations on biblical chronology.
any method of determining the age of earth materials or objects of organic origin based on measurement of either short-lived radioactive elements or the amount of a long-lived radioactive element plus its decay product.
A method for determining the age of an object based on the concentration of a particular radioactive isotope contained within it.The amount of the isotope in the object is compared to the amount of the isotope's decay products.The object's approximate age can then be figured out using the known rate of decay of the isotope.James Hutton, a physician-farmer and one of the founders of the science of geology, wrote in 1788, “The result, therefore, of our present inquiry is, that we find no vestige of a beginning, — no prospect of an end.” Although this may now sound like an overstatement, it nicely expresses the tremendous intellectual leap required when geologic time was finally and forever severed from the artificial limits imposed by the length of the human lifetime.By the mid- to late 1800s, geologists, physicists, and chemists were searching for ways to quantify the age of the Earth.Lord Kelvin and Clarence King calculated the length of time required for the Earth to cool from a white-hot liquid state; they eventually settled on 24 million years.