Science of carbon dating
Because the cosmic ray bombardment is fairly constant, there’s a near-constant level of carbon-14 to carbon-12 ratio in Earth’s atmosphere.Organisms at the base of the food chain that photosynthesize – for example, plants and algae – use the carbon in Earth’s atmosphere.
Clearly they can’t be any more recent than the Dissolution of 1538.
In 1949, chemist Willard Libby developed Carbon-14 dating analysis, and won a Nobel Prize for the process in 1960.
It compares the level of one radioactive carbon atom (14C), which decays at a measurable rate over time, with the level of another, more stable carbon (C) atom.
Aboveground nuclear testing almost doubled the amount of carbon-14 in the atmosphere. The black arrow shows when the Partial Test Ban Treaty was enacted that banned aboveground nuclear tests. A special kind of radiocarbon dating: Bomb radiocarbon dating.
As we mentioned above, the carbon-14 to carbon-12 ratio in the atmosphere remains nearly constant.