A geomagnetic survey of Ammaia: a contribution to understanding Roman urbanism in Lusitania

Abstract

This paper presents the results of geomagnetic field survey undertaken in three stages (July 2009-October 2010) within the area of the Roman town of Ammaia (Marvao, Alto Alentejo, Portugal), some 120 km northwest of Merida (fig. 1). The principal goal was to map the full extent of sub-surface archaeological features within the archaeological park owned by the Fundacao Cidade de Ammaia and those neighbouring properties which can be argued to fall within the walls (fig. 2). The integration of the data collected through several survey techniques tested at Ammaia is still ongoing. Topographical and threedimensional geophysical data from ground-penetrating radar and earth-resistivity survey will soon permit more detailed spatial, volumetric and diachronic interpretations of targeted areas. Other approaches, such as limited excavations and other types of survey (GPR, earth-resistance, DGPS, augerings, artefact surveys, metal-detector surveys, and scanning of standing architecture) (fig. 3), have been presented elsewhere, while a full discussion of the surveys of the forum area is the subject of a recent paper.1 This article presents the data collected through gradiometer survey2 and its initial archaeological interpretation leading to a complete town plan. Based on this data we will assess the urban characteristics of a