Radiocarbon dates on marine shell and other materials of marine origin appear significantly older than contemporaneous samples of terrestrial/atmospheric origin. Misunderstandings regarding the mechanisms that give rise to this “marine reservoir effect” (MRE), the terminology used to define it, and the mathematics used to describe it cause many coastal archaeologists to distrust or misinterpret marine shell dates. The recent release of a reformulated 14C calibration curve for marine samples (Marine20), which necessitates recalculation of all local reservoir age corrections, may add to the confusion. Here, we review the benefits of dating shell; provide a plain-language explanation of the mechanical, chemical, biological, and cultural processes that give rise to age disparities associated with the MRE; and offer advice to archaeologists intending to date marine shell. Our hope is that these comments will not only aid archaeologists in the planning and interpretive stages of research but also assist in assessing the reliability of legacy chronologies based on marine materials. More broadly, we encourage careful evaluation of all sources of uncertainty in all 14C chronologies, whether based on terrestrial or marine materials.

AMS radiocarbon dating has been widely applied in Palaeolithic art research and its value has been proven over the past three decades. Yet it still suffers from issues that need to be discussed and analysed to improve future sampling strategies and strengthen the interpretation of the results. This study presents new AMS dates for the parietal art in Cueva de Las Chimeneas in northern Spain, describes the quality of the samples, and discusses their reliability. The joint assessment of the dates and its comparison with previously obtained dates as well as stratified and dated portable art makes it possible to put forward a hypothesis about the time of creation of the cave's parietal art and the degree of synchrony or diachrony in its production. Consequently, it is proposed that the cave art at Las Chimeneas was created in the lower Magdalenian, between 19,000 and 17,500 cal bp.

From 2014 to 2020, we compiled radiocarbon ages from the lower 48 states, creating a database of more than 100,000 archaeological, geological, and paleontological ages that will be freely available to researchers through the Canadian Archaeological Radiocarbon Database. Here, we discuss the process used to compile ages, general characteristics of the database, and lessons learned from this exercise in “big data” compilation.

The Middle Mississippian component at Aztalan was a mixed, Late Woodland / Mississippian occupation sited within a heavily fortified habitation and mound center that is located on a tributary of the Rock River in Wisconsin. It represents the northernmost large Cahokian-related village recorded. The Oneota Lake Koshkonong Locality of the Rock River drainage is located approximately 20 km south of Aztalan, and it consists of a 25 km2 area along the northwest shore with a small cluster of habitation settlements. Sixty-eight radiocarbon measurements have been obtained from Aztalan, and 52 from Oneota settlements in the Lake Koshkonong Locality. We discuss how to best interpret this dataset, and we use Bayesian chronological modeling to analyze these dates. The results suggest that (1) Aztalan's Late Woodland (Kekoskee phase) occupation began in the AD 900s or early AD 1000s, (2) Aztalan's Mississippian occupation ceased in the AD 1200s, (3) Oneota occupations at Lake Koshkonong began after AD 1050 and were established by the AD 1200s, and (4) Oneota occupations at Lake Koshkonong continued after Aztalan's Mississippian abandonment until at least the late AD 1300s. Additionally, the results demonstrate that Aztalan was fortified with a palisade with bastions for much of the Mississippian occupation, suggesting a contested presence in a multiethnic landscape.

In a recent article, Kunz and Mills (2021) report 10 drawn, a speo finished, turquoise blue, IIa40 beads manufactured in Venice and recovered from three late precontact sites in the Alaskan Arctic. They argue that these beads date to the fifteenth century, predating Columbus's arrival in the Americas. This conclusion is certainly in error because beads of this type were not manufactured prior to approximately AD 1560. The historical and archaeological evidence for this dating is substantial. Additionally, the elemental and radiocarbon evidence presented by Kunz and Mills (2021) supports a late sixteenth- to early seventeenth-century date for these beads.

Hernando de Soto's expedition through the southeastern United States between 1539 and 1543 is often regarded as a watershed moment for the collapse of Indigenous societies across the region. Historical narratives have proposed that extreme depopulation as a result of early contact destabilized Indigenous economies, politics, networks, and traditions. Although processes of depopulation and transformation were certainly set in motion by this and earlier colonial encounters, the timing, temporality, and heterogeneous rhythms of postcontact Indigenous histories remain unclear. Through the integration of radiocarbon and archaeological data from the Mississippian earthen platform mound at Dyar (9GE5) in central Georgia, we present a case of Indigenous endurance and resilience in the Oconee Valley that has long been obfuscated by materially based chronologies and typologies. Bayesian chronological modeling suggests that Indigenous Mississippian traditions persisted for up to 130 years beyond contact with European colonizers. We argue that advances in modeling radiocarbon dates, along with meaningful consultation/collaboration with descendant communities, can contribute to efforts that move us beyond a reliance on materially based chronologies that can distort and erase Indigenous histories.

In this article, we use the precision of Bayesian modeled radiocarbon dates to reconstruct a generational history of Late Preclassic (300 BC–AD 250) Cerros (Cerro Maya), Belize. This research was made possible by long-curated excavation records and material remains now housed at the Florida Museum of Natural History, Gainesville. Our interpretations build on earlier research and refine the temporal resolution significantly, enabling us to view site development from the perspective of adjacent generations sharing a lived experience. Here we examine material evidence of their collective actions as they built new buildings and renovated aging ones, characterizing their roles in inventing a visual future for the Late Preclassic Maya port that engaged ancestral actions while reinventing the landscape.

The late Pleistocene–early Holocene archaeological record of the interior Pacific Northwest is dominated by what has been regionally referred to as the Western Stemmed Tradition (WST). While various efforts have attempted to clarify the chronology of this tradition, these have largely focused on data from the Great Basin and have been disproportionately preoccupied with establishing the beginning of the tradition due to its temporal overlap with Clovis materials. Specifically focusing on the Columbia Plateau, we apply a series of Bayesian chronological models to create concise estimates of the most likely beginning, end, and span of the WST. We then further explore its chronology by modeling its temporal span under various parameters and criteria so as to better identify places in the chronology that need further work and those that are robust regardless of data iteration. Our analysis revealed four major findings: (1) WST conservatively dates between 13,000 and 11,000 cal BP, likely extending to ~13,500 cal BP; (2) the most problematic period for WST is its termination; (3) the WST is incredibly long-lived compared to roughly contemporary Paleoindian traditions; and (4) the WST was seemingly unaffected by the onset of the Younger Dryas.