Ground truth validated 3D electrical resistivity imaging of the archaeological deposits at Arma Veirana cave (northern Italy)

Abstract

We present 3D electrical resistivity tomography (ERT) imaging of the archaeological deposits at Arma Veirana cave (northern Italy), to date only partially explored. The archaeological importance of the cave is due to the presence of a rich Mousterian layer, traces of Late Upper Palaeolithic (Epigravettian) temporary occupations and an Early Mesolithic burial of a female newborn. ERT is rarely employed in Palaeolithic cave contexts because Palaeolithic remains are typically disseminated in loose deposits and either do not possess high electrical resistivity contrasts or are too small to be detected. Furthermore, some issues can derive from the confined environment in caves. In this view, our study represents an opportunity to assess the capability of this geophysical method to retrieve subsurface information of Palaeolithic cave deposits and create a framework for the improvement of ERT applications in such a peculiar cave context. The aim of this study was to define the features of the deposits (i.e. geometry, thickness and sediment distribution) and to map the morphology of the underlying bedrock. Results reveal that the thickness of the deposits varies both along the primary axis of the cave and transverse to it. This study allowed the recognition of shallow, meter-sized, fine-grained sediment-filled structures with a longitudinal orientation with respect to the primary axis of the cave, as well as a possible erosional-like structure. The cross-validation of geophysical results with the archaeological evidence (the Early Mesolithic newborn burial and Epigravettian artefacts) confirms that the low-resistivity unit could be the most promising from an archaeological point of view.