Microstratigraphic analysis of the main Roman road in Hispania: the Via Augusta where it passes through the Ianus Augustus (Mengíbar, Spain)

Abstract

Roman roads are omnipresent in the Mediterranean basin. Despite the methodological advances achieved, interdisciplinary studies including geoarchaeological techniques are still rare. The aim of this study is to offer a microstratigraphic analysis of an important Roman road in order to characterise the raw materials and construction techniques used to build it and their evolution over time. Our research focuses on the Via Augusta, the longest road in Roman Hispania, where it passes through the Ianus Augustus (Mengíbar, Spain), a monumental complex on the frontier between the provinces of Baetica and Tarraconensis. Archaeological excavations of this road have revealed vertical stratigraphic variations, suggesting the presence of several transit surfaces and repair works. A protocol was designed to characterise the road deposits at the microscale, where micromorphology revealed six overlying roads and their construction techniques. The combination of micromorphology, µ-XRF and the study of the textural parameters of the deposits allowed us to identify the raw materials used and their sources, as well as the specific features generated during the construction and use of the road. The results show how the technical solutions used survived as a tradition for centuries, and how the repair works identified in the stratigraphic sequence have a correlation with the road maintenance works mentioned in the Roman epigraphic record of Hispania Baetica. This study shows how detailed microstratigraphic analyses of Roman roads are very effective in the characterisation of road biographies.