HOPEWELL BLADELETS: A BAYESIAN RADIOCARBON ANALYSIS G. Logan Miller Hopewell bladelets may be the most common diagnostic artifact of the Hopewell Interaction Sphere. As such, they are often recognized as a Middle Woodland “index fossil” and a key materialized indication of Hopewell ceremonialism. However, few formal analyses of their occurrence across space and time exist. Drawing on published reports, as well as an extensive review of the unpublished gray literature, I present a Bayesian analysis of radiocarbon-dated, bladelet-bearing features from across Ohio. The Bayesian model provides insight into previously unrecognized temporal variation in this element of Hopewell material culture. Results indicate that bladelets are present from around the BC/AD switch to nearly AD 500 in certain portions of the state. Analysis by major drainages indicates that bladelets occur earliest in southern and central Ohio before subsequently spreading north to the Lake Erie region. Understanding the spatial and temporal variation in artifact classes such as Hopewell bladelets is essential to explaining prehistoric cultural processes. Las navajillas Hopewell pueden considerarse el artefacto de diagnóstico más común de la esfera de interacción Hopewell. Como tal, a menudo se les reconoce como “fósil índice” del Silvícola medio y un indicador material clave del ceremonialismo Hopewell. Sin embargo, existen pocos análisis formales de su ocurrencia a través del espacio y el tiempo. Con base en informes publicados y en una extensa revisión de la literatura gris inédita, se presenta un análisis bayesiano de rasgos contenientes navajillas y fechados por radiocarbono a lo largo del estado de Ohio. El modelo bayesiano revela una variación temporal no anteriormente reconocida en este elemento de la cultura material Hopewell. Los resultados indican que las navajillas estuvieron presentes en ciertas partes del estado entre el primer y quinto siglo dC. Tomando en cuenta su distribución alrededor de los drenajes principales, el análisis revela que las navajillas ocurren primero en Ohio meridional y central y luego se difunden hacia la región del Lago Erie en el norte. Un entendimiento preciso de la variación espacial y temporal de clases de artefactos como las navajillas Hopewell es esencial para explicar los procesos culturales prehistóricos. U nderstanding the spatial and temporal distribution of patterns in material cul- ture has always been of central impor- tance to archaeological inference (Binford 1965; Dunnell 1971; McKern 1939; Thomas 1894; Willey and Phillips 1958; Willey and Sabloff 1993). Since the mid-twentieth century, radio- carbon dating has played a vital role in building archaeological chronologies worldwide (Libby 1955), and accelerator mass spectrometry dates and Bayesian modeling have led to what many describe as a continuing radiocarbon revolution (Bayliss 2009). As a baseline for the explana- tion of variation in material culture, one must first establish a detailed understanding of the spatiotemporal distribution of material culture. G. Logan Miller Department of Sociology and Anthropology, Campus Box 4660, Illinois State University, Normal, IL 61790, USA (glmill1@illinoisstate.edu) This issue is particularly important in cases where large-scale regional similarities may mask local variation. In these cases, archaeologists often downplay local variation by focusing on shared regional material culture. Such is the case with Hopewell ceremonialism in eastern North America, while similar arguments can be made for the archaeology of Clovis, Adena, or Mississippian. As Charles recently lamented, there is a widely held “conception (or at least pre- sentation) of Hopewell as a uniform and singular entity in which any temporal and spatial variation in the manifestations of the phenomenon is largely ignored” (2012:471). Although studies of Hopewell variation exist (e.g., Charles 1995; Clay 2014; Emerson et al. 2013; Struever 1964; American Antiquity 83(2), 2018, pp. 224–243 Copyright © 2018 by the Society for American Archaeology doi:10.1017/aaq.2017.64 224