Because of the rates of decay, radiocarbon dating is not useful for sites older than 50,000 years old.

The method was developed by Willard Libby in the late 1940s and soon became a standard tool for archaeologists.

Libby received the Nobel Prize for his work in 1960.

The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen.

Kris Hirst Definition: Radiocarbon dating uses the amount of Carbon 14 (C14) available in living creatures as a measuring stick.

All living things maintain a content of carbon 14 in equilibrium with that available in the atmosphere, right up to the moment of death.

When an organism dies, the amount of C14 available within it begins to decay at a half life rate of 5730 years; i.e., it takes 5730 years for 1/2 of the C14 available in the organism to decay.Comparing the amount of C14 in a dead organism to available levels in the atmosphere, produces an estimate of when that organism died.So, for example, if a tree was used as a support for a structure, the date that tree stopped living (i.e., when it was cut down) can be used to date the building's construction date.Studies have indicated that the amount of carbon in the atmosphere has not remained constant, and beginning about 1500 BC, dates provided by radiocarbon are too recent.These dates become farther off the older the time is indicated.Calibration of radiocarbon dates to offset the error is accomplished by a fairly complicated set of formulas, but they primarily use comparison to dendrochronology dating referents.