Resistivity and Magnetics of the Roman Town Carnuntum, Austria: an Example of Combined Interpretation of Prospection Data W. NEUBAUER 1,2 * AND ALOIS EDER-HINTERLEITNER 2 1 Interdisziplina ¨ re Einrichtung fu ¨r Archa ¨ ologie der Universita ¨ t Wien, Geophysikalische Prospektion, Franz Kleingasse 1, A-1190 Wien, Austria 2 Zentralanstalt fu ¨r Meteorologie und Geodynamik, Abt. Geophysik, Hohe Warte 38, A-1190 Wien, Austria ABSTRACT In the well-known Roman town Carnuntum in the eastern part of Austria, systematic geophysical prospection has started recently. A five hectare area of the civil town, the former residence of Emperor Marcus Aurelius, was prospected by resistivity and magnetic surveys in 1996. Resistivity and magnetic surveys are arithmetically combined or colour coded in a digital image processing technique for a combined archaeological interpretation using geographical information systems’ procedures. Image combination facilitates correlation of the two data sets and offers new insights for the interpretation process. The results of the first survey show the layout of the town, i.e. roads and insulae. A part of the Roman town at the River Danube is now recovered, unveiling a lot of archaeological information about the hitherto unexplored archaeological area. A representative building and a square have been identified that might represent the town’s forum, with the building probably representing the curia. * c 1997 John Wiley & Sons, Ltd. Archaeol. Prospect. 4: 179–189, 1997. Key words: magnetic prospection; caesium gradiometer; resistivity survey; image processing; Roman town; GIS. Introduction Magnetic and resistivity surveys are the most successful geophysical prospection techniques for archaeological purposes (Clark, 1990; Neubauer, 1990; Scollar et al, 1990). Resistivity mapping using RM15 is three times as time consuming as magnetic surveying using caesium gradiometers for half the spatial resolution and therefore normally is applied only to areas where detailed information required. The areas mapped using resistivity surveys are decided after the interpret- ation of the digital image representation of the magnetic data, the so-called magnetogram (Neubauer and Melichar, 1996). Magnetic surveys carried out with an automatic caesium gradi- ometer in a standard raster of 0.25  0.5 m very clearly identify ditches, pits, ovens, bricks, woo- den palisades, etc. Large-scale magnetic surveys (45 ha), e.g. on a Roman villa rustica, identify not only the location of the main buildings but the whole habitation, with the associated field struc- tures and cemeteries. In contrast, the walls of Roman buildings are not usually resolved with great clarity in magnetic surveys. Often they are obscured by large anomalies caused by bricks and tiles inside and around the buildings. An CCC 1075±2196/97/040179±11$17.50 Received 14 October 1997 # 1997 John Wiley & Sons, Ltd. Accepted 14 January 1998 Archaeological Prospection, Vol. 4, 179±189 (1997) *Correspondence to: W. Neubauer, Interdisziplina Ère Einrich- tung fu È r Archa Èologie der Universita Èt Wien, Geophysikalische Prospektion, Franz Kleingasse 1, A-1190 Wien, Austria. Email: archeo@zamg.ac.at