Tree-ring-radiocarbon dating paraffin-conserved charcoal at the Mississippian Center of Kincaid, Illinois, USA

Archival charcoal tree-ring segments from the Mississippian center of Kincaid Mounds provide chronometric information for the history of this important site. However, charcoal recovered from Kincaid was originally treated with a paraffin consolidant, a once common practice in American archaeology. This paper presents data on the efficacy of a solvent pretreatment protocol and new wiggle-matched 14C dates from the largest mound (Mound 10) at Kincaid. FTIR and 14C analysis on known-age charcoal intentionally contaminated with paraffin, as well as archaeological material, show that a chloroform pretreatment is effective at removing paraffin contamination. Wiggle-matched cutting dates from the final construction episodes on Mound 10 at Kincaid, indicate that the mound was used in the late 1300s with the construction of a unique structure on the apex occurring around 1390. This study demonstrates the potential for museum collections of archaeological charcoal to contribute high-resolution chronological information despite past conservation practices that complicate 14C dating.