Carbon dioxide is distributed on a worldwide basis into various atmospheric, biospheric, and hydrospheric reservoirs on a time scale much shorter than its half-life.
Measurements have shown that in recent history, radiocarbon levels have remained relatively constant in most of the biosphere due to the metabolic processes in living organisms and the relatively rapid turnover of carbonates in surface ocean waters.
In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.
Although relative dating can work well in certain areas, several problems arise.
Carbon-14 was discovered on February 27, 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, California.
Its existence had been suggested by Franz Kurie in 1934. The primary natural source of carbon-14 on Earth is cosmic ray action on nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide.
It is in knowing what made past cultures cease to exist that could provide the key in making sure that history does not repeat itself.
Over the years, archaeology has uncovered information about past cultures that would have been left unknown had it not been with the help of such technologies as radiocarbon dating, dendrochronology, archaeomagnetic dating, fluoride dating, luminescence dating, and obsidian hydration analysis, among others.
For example, Christian time counts the birth of Christ as the beginning, AD 1 (Anno Domini); everything that occurred before Christ is counted backwards from AD as BC (Before Christ).
Each sample type has specific problems associated with its use for dating purposes, including contamination and special environmental effects.
More information on the sources of error in carbon dating are presented at the bottom of this page.
C, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.
Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues (1949) to date archaeological, geological and hydrogeological samples.