Fischer and Heinemeier (2003) present a hypothesis that the freshwater reservoir effect produces old apparent
ages for radiocarbon dates run on charred cooking residues in regions where fossil carbon is present in groundwater. The
hypothesis is based in part on their analysis of dates on charred cooking residues from 3 inland archaeological sites in Denmark
in relation to contextual dates from those sites on other materials. A critical assessment of the dates from these sites suggests
that rather than a pattern of old apparent dates, there is a single outlying date—not sufficient evidence on which to build
a case for the freshwater reservoir effect.