Radiocarbon dating age
To give an example if a sample is found to have a radiocarbon concentration exactly half of that for material which was modern in 1950 the radiocarbon measurement would be reported as 5568 BP.
For two important reasons, this does not mean that the sample comes from 3619 BC: Many types of tree reliably lay down one tree ring every year.
Archaeologists have long used carbon-14 dating (also known as radiocarbon dating) to estimate the age of certain objects.
Traditional radiocarbon dating is applied to organic remains between 500 and 50,000 years old and exploits the fact that trace amounts of radioactive carbon are found in the natural environment.
Libby, a Professor of Chemistry at the University of Chicago, predicted that a radioactive isotope of carbon, known as carbon-14, would be found to occur in nature.
Radiocarbon measurements are always reported in terms of years `before present' (BP).
This figure is directly based on the proportion of radiocarbon found in the sample.
The new method is based on the fact that over the past 60 years, environmental levels of radiocarbon have been significantly perturbed by mid-20th-century episodes of above-ground nuclear weapons testing.
Before the nuclear age, the amount of radiocarbon in the environment varied little in the span of a century.The wood in these rings once laid down remains unchanged during the life of the tree.