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

Abstract

In order to track diachronic changes in archaeological sequences, researchers typically partition time into stratigraphic layers defined during fieldwork, which serve as the framework for ensuing analyses. These analytical units have a significant impact on archaeological inference, defining its resolution, and influencing both the study of cultural assemblages and the reconstruction of past environments. However, field layers are seldom re-evaluated after excavation despite the fact that archaeological deposits are now commonly recognised as often containing material ‘mixed’ together by site formation processes, excavation techniques or analytical practices. Although the analysis of intra-site spatial data clearly offers a means to overcome these issues, our literature review of 192 journal articles revealed the potential of this data (notably vertical projections of piece-plotted artefacts) to be under-exploited in Prehistoric archaeology. Here we advocate for the development of a more spatially-informed framework for interpretation that we refer to as Post-Excavation Stratigraphies or PES. After proposing a definition for “PES”, we attempt to develop a framework for theoretical considerations underlying their implication, importance, and potential. Three main benefits of PES are highlighted: ensuring assemblage reliability, increased chronological and spatial resolution, and more reliable interpretations based on a multi-stratigraphic approach. We contend that the stratigraphy defined during fieldwork is insufficient and potentially misleading. By providing a different “stratigraphic view” of the same sequence, each specialist can contribute data that, when combined, produces a better understanding of interactions between changes in, for example, technological or cultural traditions, subsistence strategies, or paleoenvironments.

SEAHORS: Spatial Exploration of ArcHaeological Objects in R Shiny

“…The aim of the SEAHORS application is to offer tools for the spatial exploration of archaeological objects to a broader audience, through a point-and-click interactive interface, in a free and open-source environment. We hope that this software (in its current form and through future additions) will foster the spatial exploration of archaeological sites and, in particular, the practice of post-excavation stratigraphic analysis (Discamps et al 2023).…”

“…Using this three-dimensional (3D) spatial data to virtually reconstruct the excavated deposits offers the opportunity to investigate spatial (horizontal and vertical) organizations of plotted archaeological objects. Such exploration allows to attest, confirm or invalidate stratigraphic and spatial observations made in the field, and to generate postexcavation stratigraphies and assemblages (see Discamps et al 2023 for a recent review of such use).…”