Potential for¹⁴C Dating of Biogenic Carbonate in Hackberry (Celtis) Endocarps

Hackberry endocarp ( Celtis sp.) contains significant amounts (up to 70 wt%) of biogenic carbonate that is nearly pure aragonite (CaCO 3 ). Because of their high mineral content, hackberry endocarps are found abundantly in Tertiary and Quaternary sediments and are very common in many North American archaeological sites. We analyzed the 14 C content of different components of modern hackberries including the biogenic carbonate in hackberry endocarps collected at known times over the past century. The 14 C content of the endocarp carbonate accurately records the 14 C content of the atmosphere. 14 C dates of fossil endocarp carbonates compared favorably with dates obtained by other means at archaeological and geological sites ranging in age from the late Pleistocene through the early Holocene. We therefore suggest that hackberry endocarp is a suitable substrate for 14 C dating provided that its morphological and mineralogical integrity is preserved.