Cosmogenic dating archaeology
The occurrence of natural radioactive carbon in the atmosphere provides a unique opportunity to date organic materials as old as roughly 60,000 years.
Unlike most isotopic dating methods, the conventional carbon-14 dating technique is not based on counting daughter isotopes.
Newly created carbon-14 atoms were presumed to react with atmospheric oxygen to form ) molecules.
Radioactive carbon thus was visualized as gaining entrance wherever atmospheric carbon dioxide enters—into land plants by photosynthesis, into animals that feed on the plants, into marine and fresh waters as a dissolved component, and from there into aquatic plants and animals.
It is clear that carbon-14 dates lack the accuracy that traditional historians would like to have.
A final problem of importance in carbon-14 dating is the matter of sample contamination.
And, if so, has today’s uniform level prevailed throughout the recent past?
After showing the essential uniformity of carbon-14 in living material, Libby sought to answer the second question by measuring the radiocarbon level in organic samples dated historically—materials as old as 5,000 years from sources such as Egyptian tombs.
Whenever the number of cosmic rays in the atmosphere is low, the rate of carbon-14 production is correspondingly low, resulting in a decrease of the radioisotope in the carbon-exchange reservoir described above.
Studies have revealed that the atmospheric radiocarbon level prior to 1000 it was about 8 percent above what it is today.
Search for cosmogenic dating archaeology:
In short, all parts of the carbon cycle were seen to be invaded by the isotope carbon-14.