New Visual Analytics Tool and Spatial Statistics to Explore Archeological Data: The Case of the Paleolithic Sequence of La Roche-à-Pierrot, Saint-Césaire, France

Abstract

The archeological record of La Roche-à-Pierrot (France) is central to debates on the Middle to Upper Paleolithic transition. To this day, it is the only site to have provided a relatively complete Neandertal skeleton associated with an industry identified as transitional, the Châtelperronian, which had been attributed until then to Homo sapiens. The site was the subject of several excavation campaigns led by F. Lévêque in the 1970s, 1980s, and 1990s, and ongoing fieldwork resumed in 2013. Spatial representations and statistical analyses of the original excavation data are of invaluable help in assessing the coherence of the first archeological stratigraphy established in the 1970s. A 3D reconstruction of Lévêque's spit record was developed for exploratory purposes, based on reassessment of the faunal collection and completed by information recorded in the excavation notebooks filled out by Lévêque's team. It was then used in order to evaluate the feasibility of modeling the data recorded during the first excavations. Geovisualization tools, associated with appropriate 3D spatial statistics using the Queen contiguity applied to the archeological sequence, such as the similarity and coherence indices, provided an understanding of the spatial inconsistencies in the first archeological sequence, as well as revealed the spatial organization (geometry) of the archeostratigraphic units. The resulting interactive visualization application provides researchers with a new tool to explore the stratigraphic units spatially, as well as according to their indices. Where inconsistencies are observed, use of similarity and coherence indices allows discussion of any biases potentially related to topography, spatial heterogeneity of the deposits (facies), excavation history, or primary data acquisition/recording. Such spatial analyses contribute to a better understanding of site formation processes and provide novel means to explore archival information interactively, as well as to produce models including data from old and new excavations on the same site.

Breaking free from field layers: the interest of Post-Excavation Stratigraphies (PES) for producing reliable archaeological interpretations and increasing chronological resolution

“…Pushing forward PES requires the development of tools for facilitating the spatial exploration of archaeological data in three dimensions as well as more advanced statistical treatment of data. For the former, several software or R packages speci cally designed for the three-dimensional exploration of intra-site spatial data exist, such as the NewPlot program (Dibble & McPherron, 1988), scripts adapted for the DataDesk software (Lacrampe-Cuyaubère, 1997), and Shiny R applications designed for the Poeymaü (Plutniak, 2021b;Plutniak, 2022a) and Saint-Césaire (Couillet et al, 2022) sequences. The development of new user-friendly tools for people unfamiliar with GIS would be useful to the more widespread application of PES studies.…”

SEAHORS: Spatial Exploration of ArcHaeological Objects in R Shiny

“…However, using a programming language can be challenging for untrained archaeologists. The Shiny package offers the possibility to build a point-and-click interactive interface, allowing for a more user-friendly experience (Chang et al 2022). SEAHORS also relies on the Plotly package (Sievert et al 2017), offering interactive data visualization by displaying information associated with each point directly on the visualized plots.…”

archeoViz: an R package for the Visualisation, Exploration, and Web Communication of Archaeological Spatial Data

“…-Shannon McPherron's R Shiny Plot it application (unpublished), -Anthony Sécher's PyCoCu python script, • R Shiny application implementing specific statistical methods, e.g. (Couillet et al, 2022), • R packages:…”