Hidden images in Atxurra Cave (Northern Spain): A new proposal for visibility analyses of Palaeolithic rock art in subterranean environments

Abstract

Visibility has been the subject of study in Palaeolithic rock art research ever since the discovery of Altamira Cave in 1879. Nevertheless, until now, the different approaches have been based on subjective assessments, due to computational limitations for a more objective methodology. Nowadays, cutting-edge technologies such as GIS allow us to address spatial studies in caves and overcome their geomorphologically complex and closed characteristics. Here we describe an innovative methodology that uses computing tools available to any researcher to study the viewsheds of the graphic units in decorated caves. We have tested its validity on the recently discovered rock art ensemble of Atxurra Cave, in Northern Spain. We demonstrate that this technology (GIS), widely used in other fields of archaeology, especially in outdoor studies, is also useable in caverns, taking into account the complex morphologies -ceilings and diverse floor-levels, for example. These programmes have also allowed us to consider the lighting systems used by the prehistoric groups inside the cave, as well as various data previously estimated by other authors, such as the height of individuals during the European LUP. The dynamism of these tools −2.5D-, as well as the advancement of new 3D GIS technologies, will allow in the future remarkable progress in these types of structural studies for a better understanding of Palaeolithic cave art phenomena.