Radiocarbon dating coal
The carbon dioxide is absorbed by plants, and the plants are eaten by animals, thus contaminating every living thing on earth with radioactive carbon. As time passes, the C14 in its tissues is converted back into nitrogen.
If we know what the original ratios of C14 to C12 were in the organism when it died, and if we know that the sample has not been contaminated by contact with other carbon since its death, we should be able to calculate when it died by its C14 to C12 ratio.
PROBLEMS WITH RADIOCARBON DATING During the last 30 years, a new method of determining C14/C12 ratios has been developed.
Only one out of every trillion carbon atoms is C14. The C14 created in the upper atmosphere reacts with oxygen to become carbon dioxide.But in actual practice, we know neither the original ratios nor if the specimen has been contaminated and are forced to make what we hope are reasonable assumptions.The tiny initial amount of C14, the relatively rapid rate of decay (the half-life of C14 is currently about 5700 years) and the ease with which samples can become contaminated make radiocarbon dating results for samples "older" than about 50,000 years effectively meaningless.When they strike ordinary atoms in the upper atmosphere, the cosmic rays smash them apart. Some of these neutrons then collide with nitrogen atoms.This collision is less destructive than the initial collision that produced them.