Carbon dating information
The ratio of carbon-14 to carbon-12 in the atmosphere and on earth is nearly constant, although there has been some change in carbon-14 concentration over the last 10,000 years.Carbon-14 formed in the atmosphere can combine with oxygen to form carbon dioxide (CO2).Also, many fossils are contaminated with carbon from the environment during collection or preservation proceedures.When scientists first began to compare carbon dating data to data from tree rings, they found carbon dating provided "too-young" estimates of artifact age.Carbon-14 is created from nitrogen-14 in the upper atmosphere of the earth.Radiation from the sun collides with atoms in the atmosphere.
The age of the carbon in the rock is different from that of the carbon in the air and makes carbon dating data for those organisms inaccurate under the assumptions normally used for carbon dating.Nuclear tests, nuclear reactors and the use of nuclear weapons have also changed the composition of radioisotopes in the air over the last few decades.This human nuclear activity will make precise dating of fossils from our lifetime very difficult due to contamination of the normal radioisotope composition of the earth with addition artificially produced radioactive atoms.This restriction extends to animals that consume seafood in their diets, as well.Carbon dating also cannot be used on artifacts over about 50,000 years old.
by Helen Fryman Question: What about radiocarbon dating? Response: I asked several people who know about this field. (1.) C14 dating is very accurate for wood used up to about 4,000 years ago.