A03_04

Wiggle-match dating on display: minimally destructive analysis of early American museum objects

Hadden C¹, Napora K²

¹Center For Applied Isotope Studies, Athens, United States, ²William S. Webb Museum of Anthropology, Lexington, United States

Wiggle-match dating of tree-ring sequences is particularly promising for achieving high-resolution dating across periods with reversals and plateaus in the calibration curve, such as the entire post-Columbian history of North America. Here we describe the process of wiggle-match dating two museum objects of significance to 18th–19th century United States history: (1) a cypress dugout logboat exhibiting a unique combination of European and Native American design elements; and (2) a tulippoplar wood trough utilized by an enslaved workforce in the production of saltpeter. Tree rings were counted and sampled for dating from exposed, rough cross-sections in the wood, with no or minimal surface preparation, to preserve these fragile objects. Both contained relatively long tree-ring sequences (>220 rings). Single-year samples were collected from the innermost ring and at approximately 10-year intervals from the outer ~50 rings, with practically no visible damage to the objects. The samples were radiocarbon dated by AMS, and the dates were modeled in OxCal using the Sequence and Interval functions to account for uncertainty in ring counts, rather than the D_Sequence and Gap functions that are more commonly used in wiggle-match dating. By this method, the outermost tree ring of the logboat’s hull dated to 1766–1796 cal AD, and the trough to 1778–1804 cal AD (95% highest posterior density ranges). Dendrochronological dating supports the radiocarbon wiggle-match dating for both objects. This study demonstrates that high-precision dating can be achieved for 18th–19th century objects through wiggle-match dating, with minimal damage to the objects of study.