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In researching the pivotal assumptions that the methodology relies on I have found quite a range to consider: Sheridan Bowman of the Department of Scientific Research at the British Museum lists the assumptions as follows: -The atmosphere has had the same amount of C14, (in terms of production, mixing and transfer rates) in the past as it is now. Snelling lists the following assumptions: -Cosmic ray influence on the atmosphere is constant. -Carbon dioxide levels in the sea and ocean are constant.-The biosphere has had the same overall concentration of C14. Taylor, professor of anthropology at University of California Los Angeles and University of California Riverside lists the following assumptions: -The concentration of C14 has been constant over the C14 timescale. -C14 concentration in the carbon dioxide cycle is constant. -C14 decay formation and decay rates are in equilibrium (Snelling, 856).-C14 concentrations exist in all parts of the biosphere. -There has been complete and rapid mixing of C14 throughout the various carbon reservoirs on a worldwide basis. All these assumptions can be summarized as follows: 1) C14 production in the atmosphere is constant.-The death of a plant or animal, is the point at which it no longer exchanges C14 with the environment. -Carbon isotope ratios have not been altered except by that of C14 decay. 2) C14 rapidly mixes and is spread evenly throughout the biosphere. 6) C14 decay rates and formation rates are in equilibrium.Knowing that C14 degrades into nitrogen at a known rate and organisms do not take in C14 once they’re dead, then it logically follows that the presence of C14 in a dead organism will decrease over time.Therefore, by measuring the amount of C14 in an organism, it can be known how long ago it lived with high C14 remains representing a recent age and lower C14 remains representing an older age. There are in essence, two different forms of carbon dating: the original conventional methods and the more recent AMS (Accelerated Mass Spectrometry).As is common fact, plants photosynthesize and consume CO2, fixing its carbon.
Though the vast majority of CO2 is comprised of the more common and stable isotope of carbon, carbon 12 (C12), a small fraction of CO2 (one in 765 million), contains C14.C14 on average emits 15.2 beta particles per minute, or 15.2 disintegrations per minute (dpm), for every gram of carbon (Warf, 213).After one half-life (5,730 years) activity will drop to 7.6 dpm, then 3.8 dpm (Warf, 213).Animals eat the plants, ingesting the C14 which in turn enters the animal’s tissues (Warf, 212).When an organism dies, it obviously no longer eats, photosynthesizes, etc.