Benefits of using radiocarbon dating
All living organisms take up carbon from their environment including a small proportion of the radioactive isotope 14C (formed from nitrogen-14 as a result of cosmic ray bombardment).The amount of carbon isotopes within living organisms reaches an equilibrium value, on death no more is taken up, and the 14C present starts to decay at a known rate.
Others place mineral grains under a special microscope, firing a laser beam at the grains which ionises the mineral and releases the isotopes.Radioactive decay is a natural process and comes from the atomic nucleus becoming unstable and releasing bits and pieces.These are released as radioactive particles (there are many types).For an element to be useful for geochronology (measuring geological time), the isotope must be reasonably abundant and produce daughter isotopes at a good rate.Either a whole rock or a single mineral grain can be dated.This technique has become more widely used since the late 1950s.
Its great advantage is that most rocks contain potassium, usually locked up in feldspars, clays and amphiboles.
Another way of expressing this is the half-life period (given the symbol T).
The half-life is the time it takes for half of the parent atoms to decay.
The Re-Os isotopic system was first developed in the early 1960s, but recently has been improved for accurate age determinations.
The main limitation is that it only works on certain igneous rocks as most rocks have insufficient Re and Os or lack evolution of the isotopes.
The relationship between the two is: T = 0.693 / λ Many different radioactive isotopes and techniques are used for dating.