(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.