Radioactive isotope used for radiometric dating
By establishing geological timescales, radiometric dating provides a significant source of information about the ages of fossils and rates of evolutionary change, and it is also used to date archaeological materials, including ancient artifacts.
The different methods of radiometric dating are accurate over different timescales, and they are useful for different materials.
It is the principal source of information about the absolute age of rocks and other geological features, including the age of the Earth itself, and it can be used to date a wide range of natural and man-made materials.
The best-known radiometric dating techniques include radiocarbon dating, potassium-argon dating, and uranium-lead dating.
But, how can we determine how old a rock formation is, if it hasn’t previously been dated?
Scientists can use certain types of fossils referred to as index fossils to assist in relative dating via correlation.
This chain eventually ends with the formation of a stable, nonradioactive daughter nuclide.
Each step in such a chain is characterized by a distinct half-life.
When they die no new carbon-14 is taken in by the dead organism.
The results showed that Ötzi died over 5000 years ago, sometime between 33 BC. Uranium has a very long half-life and so by measuring how much uranium is left in a rock its approximate age can be worked out.