Because the isotopes we're using have a short half-life, it follows that if a rock has been buried for a few million years the quantities of these isotopes will be negligible.But when the rock becomes exposed on the surface, and so exposed to cosmic rays, these cosmogenic isotopes will begin to accumulate in the rock.The rate at which they do so will depend on a number of factors, including: If we take all the relevant factors into account, and calculate, estimate, or simply measure the amount of cosmic rays a given rock is exposed to per year, and if we measure the quantities of the cosmogenic isotopes in a sample of the rock, then we can figure out how long the rock has been exposed.The quantity of the relevant isotopes in the rock will not simply grow without limit with longer and longer exposure to cosmic rays; rather they will tend towards a maximum (a secular equilibrium): the point at which the cosmogenic cosmogenic production of unstable isotopes is equaled by their destruction by decay.As you learned in the previous page, carbon dating uses the half-life of Carbon-14 to find the approximate age of certain objects that are 40,000 years old or younger.In the following section we are going to go more in-depth about carbon dating in order to help you get a better understanding of how it works.Radiocarbon dating is a method of estimating the age of organic material.
Radiocarbon is not suitable for this purpose because it is only applicable: a) on a time scale of thousands of years and b) to remains of once-living organisms (with minor exceptions, from which rocks are excluded).
The method was then applied to two archaeological sites where reliable dates were obtained from the single bones of small mammals.
These results open the way for the routine dating of small or key bone samples. bones, teeth, antler and ivory) found in the fossil record have a tremendous informative potential relevant to the fields of archaeology, palaeoecology and the history of art and technology.
Age determinations can also be obtained from carbonate deposits such as calcite, dissolved carbon dioxide, and carbonates in ocean, lake, and groundwater sources.
Cosmic rays enter the earth's atmosphere in large numbers every day and when one collides with an atom in the atmosphere, it can create a secondary cosmic ray in the form of an energetic neutron.