Carbon dating tree
C-14 is produced in the upper atmosphere when nitrogen-14 (N-14) is altered through the effects of cosmic radiation bombardment (a proton is displaced by a neutron effectively changing the nitrogen atom into a carbon isotope).The new isotope is called "radiocarbon" because it is radioactive, though it is not dangerous. This is how carbon dating works: Carbon is a naturally abundant element found in the atmosphere, in the earth, in the oceans, and in every living creature.C-12 is by far the most common isotope, while only about one in a trillion carbon atoms is C-14.We will deal with carbon dating first and then with the other dating methods.Carbon has unique properties that are essential for life on Earth.Plants and animals naturally incorporate both the abundant C-12 isotope and the much rarer radiocarbon isotope into their tissues in about the same proportions as the two occur in the atmosphere during their lifetimes.
Unfortunately, the amount of Carbon-14 in the atmosphere has not been steady throughout history.
In mainstream scholarship alone, Manning said, "there are five major scholarly positions and possibilities -- the so-called ultra-high, high, middle, low and ultra-low or new chronologies, based on various assumptions and fragmentary evidence. This is useless for any real comparison or history.
Our work demonstrates that only the middle chronology is possible, and the likely range of debate left is about eight years, versus plus or minus 60 to 100 years.
So, we have a “clock” which starts ticking the moment something dies.
Obviously, this works only for things which were once living.