Note that, contrary to a popular misconception, carbon dating is not used to date rocks at millions of years old.Before we get into the details of how radiometric dating methods are used, we need to review some preliminary concepts from chemistry.They used pottery and other materials in sites to date 'relatively'.
Atoms are made up of much smaller particles called protons, neutrons, and electrons.
Many people are under the false impression that carbon dating proves that dinosaurs and other extinct animals lived millions of years ago.
What many do not realize is that carbon dating is not used to date dinosaurs. Carbon dating is only accurate back a few thousand years.
Carbon-14 has a half life of 5730 years, meaning that 5730 years after an organism dies, half of its carbon-14 atoms have decayed to nitrogen atoms.
Similarly, 11460 years after an organism dies, only one quarter of its original carbon-14 atoms are still around.
We know that it is older than Christendom, but whether by a couple of years or a couple of centuries, or even by more than a millenium, we can do no more than guess." [Rasmus Nyerup, (Danish antiquarian), 1802 (in Trigger, 19)].