Nobody bring up the dinosaurs dep’t — I know it’ll come up, so:
http://www.mnsu.edu/emuseum/archaeology/dating/radio_carbon.html
[snp] Radioactive carbon, produced when nitrogen 14 is bombarded by cosmic rays in the atmosphere, drifts down to earth and is absorbed from the air by plants. Animals eat the plants and take C14 into their bodies. Humans in turn take carbon 14 into their bodies by eating both plants and animals. When a living organism dies, it stops absorbing C14 and the C14 that is already in the object begins to disintegrate. Scientists can use this fact to measure how much C14 has disintegrated and how much is left in the object. Carbon 14 decays at a slow but steady rate and reverts to nitrogen 14. The rate at which Carbon decays (Half-life) is known: C14 has a half-life of 5730 years. Basically this means that half of the original amount of C14 in organic matter will have disintegrated 5730 years after the organisms death; half of the remaining C14 will have disintegrated after another 5730 years and so forth. After about 50,000 years, the amount of C14 remaining will be so small that the fossil can’t be dated reliably. [nsnp]
http://www.c14dating.com/int.html
first Americans (sidebar link):
http://www.pbs.org/wgbh/nova/first/radiocarbon.html
I thought that we couldn’t carbon date bone fossils because fossilization replaces the organic material with dissolved minerals. I was also under the impression that the R/C dating of the Shroud of Turin was of questionable value due to a fire that occured in the cathedral around the time that the tests indicated as the age of the Shroud.