Carbon 14 or radiocarbon dating
They have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all the way to apex predators, like sharks.But when gas exchange is stopped, be it in a particular part of the body like in deposits in bones and teeth, or when the entire organism dies, the ratio of carbon-14 to carbon-12 begins to decrease.It’s not absolutely constant due to several variables that affect the levels of cosmic rays reaching the atmosphere, such as the fluctuating strength of the Earth’s magnetic field, solar cycles that influence the amount of cosmic rays entering the solar system, climatic changes and human activities.Among the significant events that caused a temporary but significant spike in the atmospheric carbon-14 to carbon-12 ratio were above-ground nuclear test detonations in the two decades following World War II.There are three carbon isotopes that occur as part of the Earth's natural processes; these are carbon-12, carbon-13 and carbon-14.The unstable nature of carbon 14 (with a precise half-life that makes it easy to measure) means it is ideal as an absolute dating method.
Organisms at the base of the food chain that photosynthesize – for example, plants and algae – use the carbon in Earth’s atmosphere.Here’s an example using the simplest atom, hydrogen. Carbon-14 is an unstable isotope of carbon that will eventually decay at a known rate to become carbon-12.Radiocarbon dating uses isotopes of the element carbon. Cosmic rays – high-energy particles from beyond the solar system – bombard Earth’s upper atmosphere continually, in the process creating the unstable carbon-14. Because it’s unstable, carbon-14 will eventually decay back to carbon-12 isotopes.Stone and metal cannot be dated but pottery may be dated through surviving residue such as food particles or paint that uses organic material (8).
There are a number of ways to enter into a career in studying radiocarbon dating.
Radiocarbon dating may only be used on organic materials.