Radiocarbon Contamination

Extract

Before rushing into a revision of archaeological chronologies based upon the dates recently published in Memoir 8 of the Society for American Archaeology, the possibilities for the contamination of carbon should be considered. The dates given so far are from specimens found in widely divergent deposits and environments; they come from caves, bogs, Egyptian tombs, lake beds, deep deposits, shallow deposits, wet deposits, dry deposits, exposed deposits, and excavations; from material carefully removed and from other material which may have been molding in storage for years. The recognition of this diversity alone should produce caution in accepting radiocarbon dates as unassailable. Contamination of samples for dating can occur at a variety of times. It could happen prior to discovery or during excavation and removal, or in the archaeological laboratory, or even in the laboratory where the dating is done.