Special issue: Lithic material studies in geoarchaeology: An introduction

The papers in this special issue represent state‐of‐the‐art approaches to the study and interpretation of human exploitation of lithic materials. The contributions here apply rigorous analytical methodologies intending to elucidate the complexity of human interaction with the landscape, specifically identifying questions relating to the investment in the extraction of lithic resources. These papers move beyond the mere characterization of materials, assessing the nature of human choices, thus providing potential frameworks for subsequent investigations of mobility and resource exploitation. Geographic coverage includes Australia, Tasmania, North America, and Europe, several studies touching on chronologically key times in human history, including the transition of hunter‐gatherers to neolithic lifeways, the peopling of the Americas, all the way up to present issues. What follows is a brief summary of the approaches and key findings in each paper organized by the themes that emerge from this collection. The first paper is a rare consideration of lithic weathering or taphonomic issues and its impact on geochemical lithic sourcing of metamorphic rock. This is followed by a paper on the optically stimulated luminescence (OSL) dating of monumental stone architecture of the Australian Aborigines, and finally, a range of case studies that use diverse techniques to investigate lithic tools and stone architectural procurement. As with nearly all domains of archaeological research, revealing taphonomic processes is essential for any subsequent classification and interpretation of sites and material. Theys and Webb analyze surface weathering of the regionally exploited hornfels to create artifacts in southeast Tasmania. They demonstrate that Rb, Sr, Y, and Nb, while mobile during weathering, can successfully source these hornfels artifacts. This study also effectively applies isocon plots to identify the trace elements best suited for these weathered sources. OSL is a technique that is increasingly applied to challenging archaeological and geomorphic contexts where other dating techniques fall short. Kemp and colleagues take on the difficult goal of dating exposed stone architectural remains in the Mithaka Native Title Area in southwest Queensland, Australia. Targeting emplaced single grain quartz underlying Nunc and Kit stones using OSL combined with fallout radionuclides 137Cs and 210Pb, they are able to confidently date these structures to the mid and late 20th century. Approaching other structures in this way can complement the dating of occupation layers within them, which remain important to the Australian Aboriginal cultures. There is increasing interest in sourcing stone artifacts as multi‐instrumentation applications are becoming more precise and affordable, including the added benefit that a wider range of materials can be assessed using portable equipment. Meanwhile, research questions have become more sophisticated and focused on lithic procurement, exploring issues of cost and transport, the dynamics of trade, forager behavior, recognition of material quality, and the relationship between raw material and the tool type, to name just a few. The diverse sourcing studies presented in this issue span two continents, with unique questions directed at detailed petrographic and geochemical studies scrutinized through various multivariate statistical approaches. In the first sourcing paper, Allan and McMillan apply Raman spectroscopy to carbonaceous material in sedimentary rock to identify possible sources used by hunter‐gatherers at the Hummingbird Creek site in the Canadian Rockies of Alberta. Guided by the exclusionary Provenance Hypothesis, they test artifacts from the site and two local sources with known workshop sites using Raman spectroscopy and X‐ray fluorescence (XRF) analysis of major, minor, and trace element compositions. These data are analyzed using principal components analysis and linear discriminant analysis. The outcomes suggest that the site occupants were likely aware of the poor quality of the local material and thus imported workable toolstone material to the site. Questions remain that there may be other potential local sources that have yet to be located. Schmuck and colleagues direct their study to the role of early Holocene archaeology in the story of the peopling of the Americas using obsidian artifacts from the six earliest sites in the islands of Southeast Alaska. They focus on the geochemistry and the region's four most commonly used obsidian sources to build a source catalog and accompanying PLS‐DA model for classification of the obsidian for different portable XRF (pXRF) instruments. A distance‐decay model indicates high mobility and no relationship between core reduction intensity and distance from the source, suggesting that morphological variation of microblade cores is linked instead to quality constraints of raw materials. Lewis, Eren, and colleagues develop a case study focused on different techniques to quantify the quality (fracture predictability) of Upper Mercer chert artifacts (Northern Ohio, USA) from the source to a series of sites up to 100 km to the north. The study measures silicon dioxide (SiO2) content and loss on ignition along with direct measures of the amount of impurities represented in the chert artifacts. Statistical analysis of the data shows a consistent difference in the use of higher‐quality material at the source and lower‐quality stone at the sites distant to the outcrop. The authors propose that