Atom used in radiocarbon dating
The surplus "bomb" radiocarbon is just one of the effects human have had on the ratio of C. During the industrial revolution (1850 - present) increasing amounts of fossil fuels were combusted. Since the carbon in these fuels was ancient, it contained no radiocarbon.
As far back as there were organisms who were able to consume food containing both ordinary carbon and an isotope of carbon; the comparison of the ratios - which pinpoints the time when an organism stopped eating - gives rise to carbon dating.
Carbon dating is one type of radiometric dating, there are others.
The 14 in Carbon-14 means that the atomic weight of the carbon atom is 14 atomic mass units (AMU).
Radiocarbon dating is an radioactive isotope dating technique used in dating materials which contain the unstable carbon-14 isotope.
This can be overcome by calibration curves calculated by dating materials of precisely known age.
The best samples are tree rings, but annually laminated sediments have also produced excellent results. Chudy, Eristavi, Pagva, Povinec, Sivo, and Togonidze. Anthropogenic 14C variations in atmospheric CO2 and wines.
In fact, the natural production of radiocarbon has varied as well.
Before the industrial revolution, from 1800 - 1400 AD, the natural production of radiocarbon was high, so dates are "too young." From 1400 AD to 300 BC they are "too old," and prior to 300 BC , they are too young.
Carbon dating uses the carbon-14 isotope, with a half life of about 5700 years.