Chronological dating techniques
Radiocarbon dates are presented in two ways because of this complication.The uncalibrated date is given with the unit BP (radiocarbon years before 1950).
View the full list Radiocarbon dating has transformed our understanding of the past 50,000 years.This method requires less than 1g of bone, but few countries can afford more than one or two AMSs, which cost more than A$500,000.Australia has two machines dedicated to radiocarbon analysis, and they are out of reach for much of the developing world.The second difficulty arises from the extremely low abundance of C, making it incredibly difficult to measure and extremely sensitive to contamination.In the early years of radiocarbon dating a product’s decay was measured, but this required huge samples (e.g. Many labs now use an Accelerator Mass Spectrometer (AMS), a machine that can detect and measure the presence of different isotopes, to count the individual C atoms in a sample.The total mass of the isotope is indicated by the numerical superscript.
While the lighter isotopes C has decayed that what remains can no longer be measured. In 5,730 years half of the C in the atmosphere, and therefore in plants and animals, has not always been constant.
If 1% of the carbon in a 50,000 year old sample is from a modern contaminant, the sample will be dated to around 40,000 years.
Because of this, radiocarbon chemists are continually developing new methods to more effectively clean materials.
Moving away from techniques, the most exciting thing about radiocarbon is what it reveals about our past and the world we live in.
Radiocarbon dating was the first method that allowed archaeologists to place what they found in chronological order without the need for written records or coins.
These new techniques can have a dramatic effect on chronologies.