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Radiocarbon dating is one of the most widely used scientific dating methods in archaeology and environmental science.

It can be applied to most organic materials and spans dates from a few hundred years ago right back to about 50,000 years ago - about when modern humans were first entering Europe.

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.

Common materials for radiocarbon dating are: The radiocarbon formed in the upper atmosphere is mostly in the form of carbon dioxide. Because the carbon present in a plant comes from the atmosphere in this way, the radio of radiocarbon to stable carbon in the plant is virtually the same as that in the atmosphere.

Plant eating animals (herbivores and omnivores) get their carbon by eating plants.

Carbon dating has a certain margin of error, usually depending on the age and material of the sample used.

Carbon-14 has a half-life of about 5730 years, and therefore it is used to date biological samples up to about 60,000 years in the past.

Since Nitrogen gas makes up about 78 percent of the Earth's air, by volume, a considerable amount of Carbon-14 is produced.

Carbon-dating Carbon dating, like other radiometric dating methods, requires certain assumptions that cannot be scientifically proved.

These include the starting conditions, the constancy of the rate of decay, and that no material has left or entered the sample.

Beyond that timespan, the amount of the original C formed by irradiation of nitrogen by neutrons from the spontaneous fission of uranium, present in trace quantities almost everywhere.

For these samples, other dating methods must be used.