Radiocarbon Age Anomalies in Shell Carbonate of Land Snails from Semi-Arid Areas

Abstract

Radiocarbon age anomalies, resulting from ingestion of old carbonate, were measured in shell carbonate of live-collected snails from arid and semi-arid areas of Israel and the West Bank. The age anomalies were found to be similar to those in land snails from other climatic regions and averaged ca 1600 yr in Trochoidea seetzeni, 2200 yr in Sphincterochila spp, 800 yr in Levantina sp, and 1700 yr in coastal dune species. The differences are associated with ecological differences among taxa. The uncertainties of the age anomalies average several hundred years within each group. This renders radiocarbon dates of late Holecene snails relatively imprecise, whereas it has almost no effect on the age uncertainties of relatively old samples (ie, those with large errors of measurement). Procedures for correction for fractionation are discussed.