ABSTRACT Reversals and plateaus in the radiocarbon ( 14 C) calibration curve lead to similar 14 C ages applying to a wide range of calendar dates, creating imprecision, ambiguity, and challenges for archaeological dating. Even with Bayesian chronological modeling, such periods remain a problem when no known order—e.g., a stratigraphic sequence—exists, and especially if site durations are relatively short. Using the reversal/plateau AD 1480–1630 and the archaeology of northeastern North America as our example, we consider possible strategies to improve chronological resolution across such reversal/plateau periods in the absence of stratigraphic sequences, including uses of wood-charcoal TPQs from even very short wiggle-matches, and site phase duration constraints based on ethnohistoric and archaeological evidence.
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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 ( 14 C) 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 14 C 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 14 C “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 14 C calibration curve. We place the Jean-Baptiste Lainé site most likely in a range between ca. AD 1595–1626 (95.4% probability).
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- Award ID(s):
- 1727802
- PAR ID:
- 10359598
- Date Published:
- Journal Name:
- Radiocarbon
- Volume:
- 64
- Issue:
- 2
- ISSN:
- 0033-8222
- Page Range / eLocation ID:
- 279 to 308
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Reversals and plateaus in the radiocarbon (14C) calibration curve lead to similar 14C ages applying to a wide range of calendar dates, creating imprecision, ambiguity, and challenges for archaeological dating. Even with Bayesian chronological modeling, such periods remain a problem when no known order—e.g., a stratigraphic sequence—exists, and especially if site durations are relatively short. Using the reversal/plateau AD 1480–1630 and the archaeology of northeastern North America as our example, we consider possible strategies to improve chronological resolution across such reversal/plateau periods in the absence of stratigraphic sequences, including uses of wood-charcoal TPQs from even very short wiggle-matches, and site phase duration constraints based on ethnohistoric and archaeological evidence.more » « less
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{"Abstract":["Two parallel surface-to-bedrock ice cores (DEN-13A and DEN-13B) were drilled from the Begguya summit plateau in Denali National Park, Alaska (62.93 N 151.083 W, 3912 m asl; also known as Mount Hunter), during the summer of 2013. The summit of Begguya has a high accumulation rate and low melt rate, making it an ideal site to recover intact paleoclimate records. DEN-13A and DEN-13B, which reach depths of ~210 meters, respectively, cover at least 10,000 years (Fang et al., 2023). Shallow cores were drilled in the summers of 2019 (DEN-19A; 50 meters) and 2022 (DEN-22A; 20 meters) extend the paleoclimate record at this site through 2022. Together, these four ice cores are commonly referred to as the Denali Ice Core record or the Begguya summit plateau ice core record. A robust chronology has been developed using a combination of techniques including annual layer counting, sulfate peaks (volcanics), radiocarbon dating and the 1963 atmospheric nuclear weapons testing horizon (Fang et al., 2023). Here, we report aqueous ICP-MS elemental concentrations and Pb isotope ratio data for the top ~1,200 years (800 to 2022 CE) of the Begguya summit plateau ice core record."],"Other":["Fang, L., Jenk, T. M., Winski, D. A., Kreutz, K. J., Brooks, H. L., Erwin, E., Osterberg, E. C., Campbell, S. W., Wake, C. P., Schwikowski, M, (2023), "Early Holocene ice on the Begguya plateau (Mt. Hunter, Alaska) revealed by ice core 14 C age constraints." The Cryosphere, 17(9):4007-4020; Osterberg, E. C., Winski, D. A., Kreutz, K. J., Wake, C. P., Ferris, D. G., Campbell, S. W., Introne, D. S., Handley, M. J., Birkel, S. D., (2017), "The 1200 year composite ice core record of Aleutian Low intensification." Geophysical Research Letters, 44(14):7447-7454."]}more » « less
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