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- Site formation histories and context of human occupations at the paleolithic site of La Ferrassie (Dordogne, France)Publication . Aldeias, Vera; Sandgathe, Dennis; McPherron, Shannon; Bruxelles, Bibiana; Turq, Alain; Goldberg, PaulThe Paleolithic site of La Ferrassie (Dordogne, France) has contributed significantly to the understanding of Middle and Upper Paleolithic technocomplexes, as well as Neanderthal skeletal morphology. Excavations at the site have spanned more than a century and uncovered rich archaeological assemblages associated with the Mousterian, Chatelperronian, Aurignacian and Gravettian technocomplexes. Renewed excavations exposed a sequence spanning both Middle and Upper Paleolithic occupations in the Western Sector and low-density Mousterian deposits and Chatelperronian in the Northern Sector. Here, we report on an extensive geoarchaeological study of deposits at the western end of the site to reconstruct and interpret both the depositional history of the sediments and associated human occupations in this poorly documented part of La Ferrassie. Our results point to the nature of the site as originally a karstic cave, with the Western Sector located in what would have been the cave's mouth. The stratigraphic sequence comprises first fluvial deposition (Phase I) followed by soliflucted deposits and accretion cones that emanate from an elevated platform situated several meters above the modern road next to the site (Phase II) and, finally, spatially restricted channeling (Phase III). Most archaeological assemblages are associated with Phase II and reflect an interplay between occupations directly in this area and bones and artifacts sliding down the slope from the upper platform. Unlike in the Western Sector, in the Northern Sector - situated along the north wall and several meters inside the footprint of the cave - cold features dominate the entirety of the sequence; we interpret these as being linked to microenvironments specific to this location of the karst rather than to general (external) climatic conditions. Relevant is the identification of patterned ground formation in this area, which can be clearly linked to the "monticule" features first reported by Capitan and Peyrony and erroneously interpreted as anthropogenic in origin. Our geoarchaeological results point to a large and complex karst system, with distinct depositional sources and often locally independent sedimentary histories throughout its extent. These formation pathways have differently impacted the main occupation areas and resulted in distinct degrees of preservation of the archaeological assemblages throughout the different areas of the site.
- Reconstructing hammerstone size flake by flake: an experimental approachPublication . Li, Li; McPherron, ShannonUnderstanding force application in flake production is essential for reconstructing hominin behaviour, technological advancements and biomechanics. Extensive research has examined stone tool production, focusing on the intended material outcomes such as the cores, tools and flakes. Analyzing force application in this process requires knowledge of hammerstone selection and use. Despite progress made in understanding hammerstone selection and use, linking specific knapping outcomes to hammerstone use remains challenging. This difficulty stems from the complex relationship between fracture mechanics and material signatures in lithic artifacts. Key variables related to hammerstone use and their influence on flaking outcomes remain poorly understood. We draw on fracture mechanics to explore factors driving flake ring crack size-the circular region where the Hertzian cone, a feature of conchoidal flaking, intersects with the platform. Our experiment systematically examines how hammerstone size, velocity and strike angle-factors influencing strike force-affect ring crack and flake size under controlled conditions. We validate our findings with previously reported controlled and replicative experiments. Results show that flake ring crack size can estimate hammerstone size. Our findings mean that we can reconstruct the flaking process and particularly variability in the application of force at a level of detail previously unavailable.
- Classifying polish in use-wear analysis with convolutional neural networksPublication . Eleftheriadou, Anastasia; Djellal, Youssef; McPherron, Shannon; Marreiros, JoaoLithic use-wear analysis examines micro- and macroscopic traces on tool surfaces resulting from human use and post-depositional processes. Polish, formed through surface abrasion with different materials, is a key diagnostic feature that is increasingly analyzed using machine learning to enhance automation and standardization. However, further research is needed to explore whether deep learning approaches, in particular, can be effectively applied to use-wear analysis and to determine the optimal surface area size (e.g., patch size and microscope objectives) and model architecture (custom vs. pre-trained) for achieving the best results. This study employs convolutional neural networks (CNNs) to classify experimental polish based on contact material (wood, hide, bone) and use intensity, while also assessing optimal imaging and analytical parameters. The results of this exploratory study suggest that CNNs may effectively identify polish from bone and hide but perform less effectively with wood. The models also successfully distinguish between polish formed by short- and long-term use. Custom models outperformed pre-trained ones, particularly when using images that captured smaller areas of the tool’s surface, suggesting that bigger surface areas may lack the necessary information for optimal results. These findings underscore the need to expand use-wear datasets in terms of size and variability and optimize CNN architectures and workflows.