For the remaining period 12,400-26,000 cal yr BP, the curve is derived from independently dated marine samples such as foraminifera and corals.
A new internationally-ratified calibration curve (Int Cal09) covering the whole radiocarbon timescale (~50,000 cal yr) is being prepared by the Int Cal Working Group.
Terrestrial (Int Cal04) and Marine (Marine04) radiocarbon calibration curves for the past 26,000 cal yr BP. Calibrated ages are shown for 1σ and 2σ (68.2% and 95.4% confidence levels, respectively).
Details Calibration of a radiocarbon age of 6550 ± 40 BP of a terrestrial sample from the Northern Hemisphere, using Int Cal04 calibration curve and Ox Cal program version 3.10.
is a technique used by scientists to learn the ages of biological specimens – for example, wooden archaeological artifacts or ancient human remains – from the distant past.
It can be used on objects as old as about 62,000 years.
High-energy cosmic rays (from outside the solar system) are constantly bombarding the upper atmosphere.
The level of bomb carbon in the northern hemisphere reached a peak in 1963, and in the southern hemisphere around 1965.Follow the links below to learn more about radiocarbon dating. Radiocarbon dating uses carbon isotopes A special kind of radiocarbon dating: Bomb radiocarbon dating What is an isotope?To understand radiocarbon dating, you first have to understand the word Although an element’s number of protons cannot change, the number of neutrons can vary slightly from each atom.Calibration is necessary because the ratio is not exactly constant.A small proportion of the cosmic rays reach the surface of the earth (particularly on high mountains) and can form radiocarbon Radiocarbon is also formed (through the processes described above) in man made nuclear reactions.Because radiocarbon is a radioactive isotope, it only exists on the earth because it has been formed recently.