Comments on the Meadowcroft Rockshelter Radiocarbon Chronology and the Recognition of Coal Contaminants

Early 14C dates from Meadowcroft Rockshelter have engendered debate on the antiquity of human occupation in North America. Although the investigators of this important site conclude that particulate and nonparticulate contamination have not affected the radiocarbon dates, several points of confusion remain in regard to the question of coal contamination. We clarify these issues, provide comparative data from other sites, and recommend specific tests that are necessary to negate or support the issue of "dead carbon" contamination of radiocarbon samples.