At any particular time all living organisms have approximately the same ratio of carbon 12 to carbon 14 in their tissues.When an organism dies it ceases to replenish carbon in its tissues and the decay of carbon 14 to nitrogen 14 changes the ratio of carbon 12 to carbon 14.Radiocarbon dating involves determining the age of an ancient fossil or specimen by measuring its carbon-14 content.Carbon-14, or radiocarbon, is a naturally occurring radioactive isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecules, which then oxidize to become carbon dioxide.In general it is always better to date a properly identified single entity (such as a cereal grain or an identified bone) rather than a mixture of unidentified organic remains.Common materials for radiocarbon dating are: The radiocarbon formed in the upper atmosphere is mostly in the form of carbon dioxide. Because the carbon present in a plant comes from the atmosphere in this way, the radio of radiocarbon to stable carbon in the plant is virtually the same as that in the atmosphere.
Carbon is naturally in all living organisms and is replenished in the tissues by eating other organisms or by breathing air that contains carbon.
This article will answer several of the most common creationist attacks on carbon-14 dating, using the question-answer format that has proved so useful to lecturers and debaters. Answer: Cosmic rays in the upper atmosphere are constantly converting the isotope nitrogen-14 (N-14) into carbon-14 (C-14 or radiocarbon).
Living organisms are constantly incorporating this C-14 into their bodies along with other carbon isotopes.
This means that things like stone, metal and pottery cannot usually be directly dated by this means unless there is some organic material embedded or left as a residue.
As explained below, the radiocarbon date tells us when the organism was alive (not when the material was used).