Radioactive dating calculations
Radiocarbon dating is one such type of radiometric dating.
A process for determining the age of an object by measuring the amount of a given radioactive material it contains.
The object's approximate age can then be figured out using the known rate of decay of the isotope.
For organic materials, the comparison is between the current ratio of a radioactive isotope to a stable isotope of the same element and the known ratio of the two isotopes in living organisms.
Instead, I describe briefly only the three principal methods. These are the three methods most commonly used by scientists to determine the ages of rocks because they have the broadest range of applicability and are highly reliable when properly used.
The main point is that the ages of rock formations are rarely based on a single, isolated age measurement.
James Joly calculated that the Earth’s age was 89 million years on the basis of the time required for salt to accumulate in the oceans.
There were other estimates but the calculations were hotly disputed because they all were obviously flawed by uncertainties in both the initial assumptions and the data.
Comparing these rocks with the products of present erosion, sedimentation, and earth movements, these earliest geologists soon concluded that the time required to form and sculpt the present Earth was immeasurably longer than had previously been thought.
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.