The rate at which fission tracks occur is related to the half-life of uranium-238, which is a relative dating method based on the fact that bones buried in the ground progressively lose nitrogen and gain fluorine and other trace elements.

The rate at which these changes occur depends on the local environment.

Proteins are composed of different combinations of amino acids assembled in chain-like molecules.

If two bones from the same site have markedly different amounts of nitrogen and fluorine, it is a strong indication that they did not come from the same time period.

The bone with the least amount of nitrogen and the greatest amount of fluorine is most likely the oldest.

a research instrument primarily used in physics to accelerate streams of charged subnuclear particles to high velocities in order to sort and analyze them.

This technique is now also used to count carbon isotope atoms for radiocarbon dating.

In the Julian system, a day is added to the end of February every 4 years.

In the Gregorian system a year is a leap year if it is divisible by 4 unless it is divisible by 100 but not by 400.

The result is that the Julian calendar is out of by one day every 131 years.

The Gregorian calendar fixed this problem by changing the rules for leap years.

D.remains of a plant or animal of a species that is known to have lived only during a specific time period.

The discovery of such a fossil in an archaeological site is circumstantial evidence of the approximate time period that it was occupied.

The advantage of this technique over the conventional radiocarbon method is that it requires a far smaller sample size and can potentially provide dates going back to around 100,000 B. At present, however, AMS dates generally are for events less than organic molecules that are building blocks of proteins.