Radiocarbon dating organic
Libby and coworkers, and it has provided a way to determine the ages of different materials in archeology, geology, geophysics, and other branches of science.Some examples of the types of material that radiocarbon can determine the ages of are wood, charcoal, marine and freshwater shell, bone and antler, and peat and organic-bearing sediments.In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.
For these samples, other dating methods must be used.
Age determinations can also be obtained from carbonate deposits such as calcite, dissolved carbon dioxide, and carbonates in ocean, lake, and groundwater sources.
Cosmic rays enter the earth's atmosphere in large numbers every day and when one collides with an atom in the atmosphere, it can create a secondary cosmic ray in the form of an energetic neutron.
Back in the 1940s, the American chemist Willard Libby used this fact to determine the ages of organisms long dead.
Most carbon atoms have six protons and six neutrons in their nuclei and are called carbon 12. But a tiny percentage of carbon is made of carbon 14, or radiocarbon, which has six protons and eight neutrons and is not stable: half of any sample of it decays into other atoms after 5,700 years.