Libby thus reasoned that by measuring carbon 14 levels in the remains of an organism that died long ago, one could estimate the time of its death.
But this just means that one should not hang their whole confidence on a lone radiocarbon date.It is not correct to state or imply from this evidence that the radiocarbon dating technique is thus shown to be generally invalid.The problem with freshwater clams arises because these organisms derive the carbon atoms which they use to build their shells from the water in their environment.A number of stories are commonly circulated about a shell, or a piece of coal, or some other sample which supposedly yielded a radiocarbon date which could not possibly be correct.Such stories misrepresent the truth and do a disservice to science and public knowlege.He first noted that the cells of all living things contain atoms taken in from the organism's environment, including carbon; all organic compounds contain carbon.Most carbon consists of the isotopes carbon 12 and carbon 13, which are very stable.Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. 1979, 1986 © Harper Collins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cite This Source radiocarbon dating A technique for measuring the age of organic remains based on the rate of decay of carbon 14.Because the ratio of carbon 12 to carbon 14 present in all living organisms is the same, and because the decay rate of carbon 14 is constant, the length of time that has passed since an organism has died can be calculated by comparing the ratio of carbon 12 to carbon 14 in its remains to the known ratio in living organisms. Our Living Language : In the late 1940s, American chemist Willard Libby developed a method for determining when the death of an organism had occurred.(Aardsma, 1994, page 2.)The original reference [Trautman and Willis, page 200.] in the second case (natural gas) immediately reveals that both Whitelaw and The Answers Book have, unfortunately, neglected several very important " The sensitivity of the equipment used to make the radiocarbon measurements on these natural gas samples was limited to 30,000 to 34,000 years---the equipment was unable to measure back further. In this example, old radiocarbon dates from living clams or snails are given as evidence which discredits the reliability of radiocarbon dating. Aardsma addressed this issue in a 1989 article: The shells of freshwater clams can, and often do, give anomalous radiocarbon results.However, the reason for this is understood and the problem is restricted to only a few special cases, of which freshwater clams are the best-known example.