The other two isotopes in comparison are more common than carbon-14 in the atmosphere but increase with the burning of fossil fuels making them less reliable for study (2); carbon-14 also increases, but its relative rarity means its increase is negligible. After this point, other Absolute Dating methods may be used.Today, the radiocarbon-14 dating method is used extensively in environmental sciences and in human sciences such as archaeology and anthropology.When an animal dies it is taken out of the carbon cycle.After this, the proportion of 14-C to 12-C steadily declines. 141, page 636, August 16, 1963) showed the shell from a living mollusk to be dead for 3,000 years!This supposedly allows one to date an object by the proportion of 14-C to 12-C. Tests of Hawaiian lava flows known to be less than 200 years old have been dated up to 3 billion years old! That is, the scientists themselves do not know the effective range for 14-C.Also, All carbon dates have a "plus-minus" probable error range. An additional problem is that the true half-life of 14-C is unknown2!
In 1979, Desmond Clark said of the method “we would still be foundering in a sea of imprecisions sometime bred of inspired guesswork but more often of imaginative speculation” (3).There are three carbon isotopes that occur as part of the Earth's natural processes; these are carbon-12, carbon-13 and carbon-14.The unstable nature of carbon 14 (with a precise half-life that makes it easy to measure) means it is ideal as an absolute dating method.Radiocarbon dating may only be used on organic materials.Typically (6): The above list is not exhaustive; most organic material is suitable so long as it is of sufficient age and has not mineralised - dinosaur bones are out as they no longer have any carbon left.
It is widely used in dating fossils or archaeological samples containing organic material such as wood, charcoal, bone, shells, etc.