These isotopes are present in the following amounts C12 - 98.89%, C13 - 1.11% and C14 - 0.00000000010%.Thus, one carbon 14 atom exists in nature for every 1,000,000,000,000 C12 atoms in living material.Herein lies the true advantage of the radiocarbon method, it is able to be uniformly applied throughout the world.Included below is an impressive list of some of the types of carbonaceous samples that have been commonly radiocarbon dated in the years since the inception of the method: The historical perspective on the development of radiocarbon dating is well outlined in Taylor's (1987) book "Radiocarbon Dating: An archaeological perspective".The half-life () is the name given to this value which Libby measured at 556830 years. After 10 half-lives, there is a very small amount of radioactive carbon present in a sample.At about 50 - 60 000 years, then, the limit of the technique is reached (beyond this time, other radiometric techniques must be used for dating)."Everything which has come down to us from heathendom is wrapped in a thick fog; it belongs to a space of time we cannot measure.We know that it is older than Christendom, but whether by a couple of years or a couple of centuries, or even by more than a millenium, we can do no more than guess." [Rasmus Nyerup, (Danish antiquarian), 1802 (in Trigger, 19)].
It follows from this that any material which is composed of carbon may be dated.By measuring the C14 concentration or residual radioactivity of a sample whose age is not known, it is possible to obtain the countrate or number of decay events per gram of Carbon.By comparing this with modern levels of activity (1890 wood corrected for decay to 1950 AD) and using the measured half-life it becomes possible to calculate a date for the death of the sample.Renfrew (1973) called it 'the radiocarbon revolution' in describing its impact upon the human sciences.