Abstract
- Obtaining radiocarbon dates on objects of chronological interest is always preferable to obtaining dates on spatially associated charcoal. The development of Accelerator Mass Spectrometer (AMS) dating has expanded the number of objects that can be directly dated because it requires only a few milligrams of material. When present, charred cooking residues adhering to the interior walls of pottery allow direct dating of pottery and obtaining such dates has become standard practice worldwide. The accuracy of AMS ages derived from residues has been questioned in cases where cooking freshwater aquatic organisms may have introduced carbon from ancient carbon reservoirs into residues. Here we provide analytic protocols for examination of this phenomenon, and the results of systematic modeling of dates on residues formed from fish and maize with varying percentages of dead carbon. We present a regional case study using a large series of AMS dates on residues from the Finger Lakes region of northeastern United States to demonstrate how the paleolimnological record and lipid analysis of residues can help to determine if dates on residues from a given region are likely to have been affected by the presence of ancient carbon. In the case of the Finger Lakes, there is no evidence that ancient carbon affected the dates.