Radioactive dating isotopes
Radioactive elements are unstable; they breakdown spontaneously into more stable atoms over time, a process known as radioactive decay.
Radioactive decay occurs at a constant rate, specific to each radioactive isotope.
This method is useful for igneous and metamorphic rocks, which cannot be dated by the stratigraphic correlation method used for sedimentary rocks. Some do not change with time and form stable isotopes (i.e.
This technique is used on ferromagnesian (iron/magnesium-containing) minerals such as micas and amphiboles or on limestones which also contain abundant strontium.This method faces problems because the cosmic ray flux has changed over time, but a calibration factor is applied to take this into account.Radiocarbon dating is normally suitable for organic materials less than 50 000 years old because beyond that time the amount of 14C becomes too small to be accurately measured.When living things die, they stop taking in carbon-14, and the radioactive clock is "set"!Any dead material incorporated with sedimentary deposits is a possible candidate for carbon-14 dating.
Search for radioactive dating isotopes:
Radioactive elements were incorporated into the Earth when the Solar System formed.