A CENTENNIAL AMBIGUITY: THE CHALLENGE OF RESOLVING THE DATE OF THE JEAN-BAPTISTE LAINÉ (MANTLE), ONTARIO, SITE—AROUND AD 1500 OR AD 1600?—AND THE CASE FOR WOOD-CHARCOAL AS A TERMINUS POST QUEM

Abstract

Considered in isolation, the radiocarbon (14C) dates on short-lived plant remains from the Jean-Baptiste Lainé (formerly Mantle) site, Ontario, yield an ambiguous result: more or less similar probability around AD 1500 or alternatively around AD 1600. This village site, likely of no more than ca. 20–30 years total duration, illustrates the challenges of high-resolution dating across periods with a reversal/plateau in the 14C calibration curve. Another problem we identify is the tendency for dating probability for short-duration sites to sometimes be overly compressed as dating intensity increases under analysis with OxCal, and for probability to shift away from the real age range especially during reversal/plateau episodes. To address both issues additional constraints are necessary. While a tree-ring sequenced 14C “wiggle-match” is the best option where available, we investigate how, in the absence of such an option, use of the in-built age in wood-charcoal samples can be used to distinguish the likely correct date range. This approach can resolve ambiguities in dating, e.g., for shorter-duration Late Woodland village sites in northeastern North America, but also other short-duration cases corresponding with reversal/plateau episodes on the 14C calibration curve. We place the Jean-Baptiste Lainé site most likely in a range between ca. AD 1595–1626 (95.4% probability).

The Monongahela tradition in “real time”: Bayesian analysis of radiocarbon dates

“…Contemporary practice calls for multiple radiocarbon measures on annual plant remains, which do not have potential for built-in ages like wood charcoal. Wood charcoal may be useful through wiggle-match dating [ 83 ] or as termini post quem [ 55 ]. However, these methods have not been applied in the region.…”

“…However, these methods and techniques have not been adopted by archaeologists working in the lower upper Ohio River basin. The most active use of Bayesian analysis in northeastern North America has been in fourteenth through mid-seventeenth-century AD contexts in the northern Iroquoian region of New York, Ontario, and Que ´bec (e.g., [15,[53][54][55][56][57][58]). These analyses have shown in many cases that chronological placements of sites based on traditional archaeological practice can be substantially in error.…”

The role of radiocarbon dating in advancing Indigenous-led archaeological research agendas

“…In fact, there may be cultural aversion or resistance to incorporating European goods that is often overlooked in estimating the ages of sites. While radiocarbon dating sites in the 1480-1630 period has at times been hampered by multiple intercepts in the calibration curve, creative use of sample selection and Bayesian modelling now allows us to overcome those problems (Manning et al, 2020;Manning and Birch, 2022). There are no more excuses for relying on artefacts as passive chronological-as opposed to active cultural-markers.…”

Phaseolus vulgaris Seeds from the Late Sixteenth–Early Seventeenth Century AD Ancestral Oneida Diable Site, New York

“…The dates fall on a large reversal in the IntCal20 calibration curve resulting in multimodal probability distributions falling in the fifteenth and late sixteenth to early seventeenth centuries AD. This is a frequently encountered problem when radiocarbon dating Iroquoian sites (Manning and Birch 2022;. Birch and colleagues' (2021:23) Bayesian modeling of radiocarbon dates from Northern Iroquoian sites indicates that sites with large amounts of European metal artifacts date toward the end of the sixteenth century AD and thereafter (Birch et al 2021:23).…”