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 stratigraphy 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.

A pre-Campanian Ignimbrite techno-cultural shift in the Aurignacian sequence of Grotta di Castelcivita, southern Italy

“…In layer rsa’ , only a few miniaturized bladelets with direct retouch were identified. Several factors, including the absence of a sedimentary hiatus between the two layers, the complex formation processes typical of cave sites 111 , 112 , and the challenges in establishing a straightforward correlation between field layers and archaeological diachronic changes 113 may have contributed to this outcome. However, it is crucial to note that the occurrence of post-depositional events at the site is limited.…”