Carbon dating radio
The amount of cosmic rays reaching the Earth varies with the sun's activity, and with the Earth's passage through magnetic clouds as the solar system travels around the Milky Way galaxy.The strength of the Earth's magnetic field affects the amount of cosmic rays entering the atmosphere.Accordingly, carbon dating carefully applied to items from historical times can be useful.However, even with such historical calibration, archaeologists do not regard C produced and therefore dating the system.The dating process is always designed to try to extract the carbon from a sample which is most representative of the original organism.In general it is always better to date a properly identified single entity (such as a cereal grain or an identified bone) rather than a mixture of unidentified organic remains.
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.
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.
Furthermore, different types of plants discriminate differently.
This also has to be corrected for. Second, the ratio of C in the atmosphere at that time to be estimated, and so partial calibration of the “clock” is possible.