The older a sample is, the less (the period of time after which half of a given sample will have decayed) is about 5,730 years, the oldest dates that can be reliably measured by this process date to around 50,000 years ago, although special preparation methods occasionally permit accurate analysis of older samples.The idea behind radiocarbon dating is straightforward, but years of work were required to develop the technique to the point where accurate dates could be obtained.It takes another 5,730 for half of the remainder to decay, and then another 5,730 for half of what's left then to decay and so on.The period of time that it takes for half of a sample to decay is called a "half-life." Radiocarbon oxidizes (that is, it combines with oxygen) and enters the biosphere through natural processes like breathing and eating.In contrast to relative dating techniques whereby artifacts were simply designated as "older" or "younger" than other cultural remains based on the presence of fossils or stratigraphic position, 14C dating provided an easy and increasingly accessible way for archaeologists to construct chronologies of human behavior and examine temporal changes through time at a finer scale than what had previously been possible.The application of Accelerator Mass Spectrometry (AMS) for radiocarbon dating in the late 1970s was also a major achievement.Compared to conventional radiocarbon techniques such as Libby's solid carbon counting, the gas counting method popular in the mid-1950s, or liquid scintillation (LS) counting, AMS permitted the dating of much smaller sized samples with even greater precision.
Scientists then look for more pieces of dead wood to match and overlap the second specimen and on and on.
By carbon dating a piece of wood which has also been dated by counting its annual tree-rings, scientists can create a table by which they can convert the questionable Carbon-14 years into true calendar years.
This is how it works: scientists begin with a living tree or dead wood specimen which can be accurately dated by some reliable means.
Carbon Dating - Dendrochronology As we've already seen, in order for Carbon dating to work we need to know what the C-12 to C-14 ratio was at the time of a specimen's death.
If the ratio has fluctuated throughout the unobservable past (and we can be sure that it has), how can we determine what the ratio was during the lifetime of a specimen that lived and died before we first began measuring the ratio?