14C Dating - also called RADIOCARBON DATING, is a method of age determination that depends upon the decay of radiocarbon (14C) to nitrogen . 14Carbon is continually formed in nature by the interaction of neutrons with nitrogen-14 in the Earth's atmosphere. The neutrons required for this reaction are produced by cosmic rays interacting with the atmosphere.    Radio14Carbon molecules are present in atmospheric carbon dioxide and enters the biological carbon cycle. Living things continually consume carbon via photosynthesis and animals eat plants via the food chain. The atmospheric ratio  14C to regular carbon 12C  remains constant at 1 ppt (part per trillion).

Once an organism dies (plant, animal or their by-products), it ceases to absorb 14C, so the amount of radiocarbon present in its tissues at death steadily decreases from that point on with the time frame of 14C's half-life.  14Carbon has a half-life of 5,730 +/- 40 years i.e., half the amount of the radioisotope present at any given time will undergo spontaneous disintegration during the succeeding 5,730 years.  A half-life is the time it takes for one-half of the parent isotope to decay* to its daughter isotope (14C to 14N). Because 14Carbon decays at the constant rate of 5,730 years, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon remaining. The 14carbon method was developed by the American physicist Willard F. Libby about 1946. It has proved to be a versatile technique of dating fossils and archaeological specimens from 500 to 50,000 years old. The method is widely used by Pleistocene geologists, anthropologists, archaeologists, and investigators in related fields.   back                                                  Carbon dating equation