Radiocarbon dating used on

In 2008 we could only calibrate radiocarbon dates until 26,000 years.

Now the curve extends (tentatively) to 50,000 years.

In the 19th and early 20th century incredibly patient and careful archaeologists would link pottery and stone tools in different geographical areas by similarities in shape and patterning.

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.

From these records a “calibration curve” can be built (see figure 2, below).

A huge amount of work is currently underway to extend and improve the calibration curve.

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.Isotopes of a particular element have the same number of protons in their nucleus, but different numbers of neutrons.This means that although they are very similar chemically, they have different masses.This method requires less than 1g of bone, but few countries can afford more than one or two AMSs, which cost more than A0,000.Australia has two machines dedicated to radiocarbon analysis, and they are out of reach for much of the developing world.Moving away from techniques, the most exciting thing about radiocarbon is what it reveals about our past and the world we live in.

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