During the lifetime of an organism, the amount of c14 in the tissues remains at an equilibrium since the loss (through radioactive decay) is balanced by the gain (through uptake via photosynthesis or consumption of organically fixed carbon).However, when the organism dies, the amount of c14 declines such that the longer the time since death the lower the levels of c14 in organic tissue.These newly formed 14C atoms rapidly oxidize to form 14CO..Photosynthesis incorporates 14C into plants and therefore animals that eat the plants.This discovery meant that there are three naturally occurring isotopes of carbon: Whereas carbon-12 and carbon-13 are stable isotopes, carbon-14 is unstable or radioactive.
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.
In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.
Although relative dating can work well in certain areas, several problems arise.
Transform the radiocarbon ages into calendar dates using the calibration program CALIB (you can see this and other programs at:
New Zealand The laboratory number is a unique identifier given to each radiocarbon sample.
Hereafter these isotopes will be referred to as 12C, 13C, and 14C.