Half life carbon dating example
After about 10 half-lives, the amount of radiocarbon left becomes too miniscule to measure and so this technique isn't useful for dating specimens which died more than 60,000 years ago.
Another limitation is that this technique can only be applied to organic material such as bone, flesh, or wood. Carbon Dating - The Premise Carbon dating is a dating technique predicated upon three things: Carbon Dating - The Controversy Carbon dating is controversial for a couple of reasons.
This man-made fluctuation wasn't a natural occurrence, but it demonstrates the fact that fluctuation is possible and that a period of natural upheaval upon the earth could greatly affect the ratio.
He was inspired by physicist Serge Korff (1906–1989) of New York University, who in 1939 discovered that neutrons were produced during the bombardment of the atmosphere by cosmic rays.
So, if we find the remains of a dead creature whose C-12 to C-14 ratio is half of what it's supposed to be (that is, one C-14 atom for every two trillion C-12 atoms instead of one in every trillion) we can assume the creature has been dead for about 5,730 years (since half of the radiocarbon is missing, it takes about 5,730 years for half of it to decay back into nitrogen).
If the ratio is a quarter of what it should be (one in every four trillion) we can assume the creature has been dead for 11,460 year (two half-lives).
The amount of cosmic rays penetrating the earth's atmosphere is itself affected by things like the earth's magnetic field which deflects cosmic rays.
Precise measurements taken over the last 140 years have shown a steady decay in the strength of the earth's magnetic field.