**1. Introduction**

In the broad range of geophysical measurements applied to archaeology [1–6], electrical resistivity tomography (ERT) is today one of the most popular methods. Multichannel systems and new inversion techniques, developed between the 1980s and the 1990s, rapidly increased, in fact, the application and popularity of this technique in different archaeological contexts [7–15]. During the last 10 years, thanks to the development of 3D ERT surveys and new tools for 3D data inversion, this method enhances the possibility to reconstruct the spatial distribution and the shape of the archaeological targets, both in small or large areas, as well as in rural or urban context [16–22]. In this wide range of applications and possible uses of the ERT, undoubtedly, the main advantage offered by this method is highlighted in the contexts in which the distribution of buried large natural or artificial systems must

be defined, extended not only laterally but also in-depth. Theoretically, the penetration depth of the electrical signal depends on the total length of the ERT line, the power source, but also the electrical conductivity of the investigated systems. The use of ERT, often combined with frequency-domain electromagnetic (FDEM), also known as electromagnetic inductance (EMI) measurements, is recently mostly documented in agriculture, geomorphological, and sedimentary research applications [23–37]. Both methods are, in fact, susceptible to the di fferences in electrical conductivity of the soils, strictly related to their di fferent soil moisture content. This capability is fundamental, for example, in the identification of buried channels and corresponding palaeo-environments, or related structures, often also interesting from the archaeological point of view. The di fferences in the soil moisture content, existing between these buried structures and the hosting system, produce visible crop marks or surface evidence, identifiable by aerial and satellite images. In recent years, several scientific studies, both in geological and archaeological contexts, moving from preliminary information collected by remote sensing data, used geophysical prospection to define these buried structures [38–44]. This paper, considering these promising recent applications, shows a multidisciplinary approach carried out to characterize the fortified system of Late Bronze Age Terramara settlement of Fondo Paviani. The term "Terramara" identifies the archaeological remains of the fortified settlements di ffused in Northern Italy, more specifically in the Po Plain, between the central phase of the Middle Bronze Age and the end of the Recent Bronze Age (1600/1550–1175/1150 BC) [45,46]. A palisade or a rampart, and a wide ditch connected with a watercourse surrounded the Terramare (Figure 1).

**Figure 1.** Reconstruction of a Terramara development (Santa Rosa di Poviglio, [47], modified by authors). (**a**) Landscape view before the settlement; (**b**)" Villaggio Piccolo": a little settlement surrounded by ditch and palisade, later destroyed and covered by a rampart. (**c**) "Villaggio Grande": expansion of the small village with new fortified part with ditch and rampart. (**d**) Particular of the settlement at its maximum development, when small and big villages coexisting.

An intensive agro-pastoral economy characterized the Terramare culture. Almost every site was surrounded by a vast structured agrarian hinterland with channeling systems. In the Middle Bronze Age, the social order of the communities was tribal, while in the Recent Bronze Age, it seems that the social model was comparable to an evolved chiefdom [48–50]. At the end of the Recent Bronze Age, a general crisis, due to demographic and environmental factors, involved Terramare Culture. In the Southern Po Plain, the crisis led to a full abandonment of the settlements, while in the Northern Po Plain has registered only a contraction of the population [51,52].

The buried remains of the Terramara, thanks to the presence of palaeo-environments and related natural differences in soil moisture content with the hosting system, represents an ideal target for ERT and FDEM measurements [53,54]. The first step in this recent multidisciplinary study of the Fondo Paviani settlement (Figure 2) moved from the pieces of evidence provided by the aerial photographs (Figures 2c and 3a–c).

**Figure 2.** (**a**) Location of the embanked site of Fondo Paviani in Northern Italy (2020 aerial view from Maps-Bing modified by authors). (**b**) Fondo Paviani within the Valli Grandi Veronesi landscape (2012 photomosaic of C.G.R. aerial frames modified by authors). (**c**) Detail of the settlement landscape (1990 C.G.R. aerial frame modified by authors).


**Table 1.** List of aerial photo frames used for the photo interpretation.

**Figure 3.** Location of geophysical measurements (red lines: ERT; yellow area: FDEM) and stratigraphic section (dotted cyan line: stratigraphic section; orange line: segmen<sup>t</sup> intercepting the fortification structures). (**a**) 1955 I.G.M.I. G.A.I aerial frame (Table 1) modified by authors. (**b**) 1990 C.G.R aerial frame (Table 1) modified by authors. (**c**) 2004 C.G.R aerial frame (Table 1) modified by authors. (**d**) DTM from LIDAR data modified by authors.

The comparison between an old aerial image (Figure 3a) taken in 1955 and more recent images (Figure 3b,c) of the same area, respectively taken in 1990 and 2004, highlights the progressive attenuation of the northern boundaries of the settlement.

The relative recent intensive agricultural practice, consisting of the regularization of the soil surfaces, in some cases, determines the removal of the upper part of the soil. This practice, also adopted at the Fondo Paviani in the last 40 years, could definitively compromise the archaeological deposit of the Terramare in some parts of the farm. The elevation data obtained by LIDAR (Figure 3d) confirms local topographical modifications in the northern part of the site. Moving from these preliminary indications, a series of ERT lines collected in di fferent parts of Fondo Paviani site help in the analysis of the actual condition and extension of these palaeo buried structures. The combination of ERT and FDEM measurements, also supported, in a test area, in the identification of the multitemporal, complex palaeo-systems spatial distribution. The integration between ERT and FDEM measurements, remote sensing data, and some pieces of evidence made by archaeological excavations, provided new interesting information about the studied area. The results of this multidisciplinary approach also support new hypotheses about the original structure of the Fondo Paviani embankment system, also suggesting the best way to continue the study around this important and not wholly investigated archaeological site.

#### *Study Site Background*

The broad fortified Terramara of Fondo Paviani, located in the Verona low plain, since 2007, is the focus of a multidisciplinary project [55] directed by the Prehistoric-Protohistoric research team at the Department of Cultural Heritage of the University of Padova. The settlement, developed between the last decades of the 14th and the 11th centuries BC, represents one of the most critical contexts for understanding the Late Bronze Age historical events of the Po Plain and, more broadly, in Northern Italy. Fondo Paviani was the central place of the complex political-territorial system known as Valli Grandi Veronesi polity. Between the 13th and the beginning of the 12th century BC, the settlement became the central keystone of the relations and trades connecting the Terramare Culture on the one hand with the Alpine area and with peninsular Italy, and on the other hand with Mycenean Greece, Cyprus, and the Levant [55].

Fondo Paviani also was one of the few centers that survived in the 12th century BC at the crisis producing the collapse of the Terramare Culture. Then it became the model for the development of the later population pattern and the new international trade network focused on the central place of Frattesina, on the Po river [56–61]. The development of the Fondo Paviani settlement reflects the typical model of the evolution of the Terramare-type settlements [62,63]. In the first phase, Fondo Paviani was surrounded only by a palisade and by a small ditch without remarkable water flows. During the 13th and the beginning of the 12th century BC a wide rampart was built and a ditch connected to the wetlands of the Menago river valley surrounded the site.

At that time, the settlement, which finally took the Terramara-type shape, reached the surface of 20 ha (16 ha of inner area and 4 ha of perimetral structures), an exceptional size for a Bronze Age settlement in Italy. The new fortified system, one of the biggest of the entire Terramare world, involved the active exploitation of pre-existing river channels and alluvial ridges, implying modifications and adaptations of the related landscape. Between the second half of the 12th and the 11th century BC, Fondo Paviani su ffered a general crisis [60]. Broad areas of the settlement, for a long time occupied by houses and related infrastructures, were converted into cultivated spaces. In the last phase of the life of the settlement and many centuries after its abandonment, the wide rampart, although collapsed in several points and damaged by diggings, retained its primary function. The rampart represented an essential shield between the development of the stratification of the inner part of the settlement and the growing clogging of the ditch linking to the Menago valley [47].

#### **2. Materials and Methods**

#### *2.1. Geomorphological Setting*

The settlement of Fondo Paviani is part of the Valli Grandi Veronesi system, a lowland of Adige alluvial fan, on an alluvial ridge inside the valley of the Menago river belonging to the Bassa Pianura Veronese. The valley flows from the Adige alluvial fan through the Valli Grandi Veronesi, where it gets the shape of an N–W/S–E large depression with slight escarpments. The Menago valley is blocked by a large Late Pleistocene ridge ("Fabbrica dei Soci" ridge) immediately S–E of the site of Fondo Paviani (Figure 2). This ridge, since the Holocene, has prevented the drainage of the valley, gradually changing the whole depression in a wetland, without covering the high bump of the settlement [64].

The Valli Grandi Veronesi area is well known [64–68] for the high preservation of the Bronze Age landscape. The depth of archaeological remains in this area is very shallow (between 0.2 and 1.4 m) [69,70]. Sometimes, the topography of the ancient structures corresponds to that of the current landscape [70], where this high preservation is the result of a lucky sequence of hydrogeological and anthropic events in the area from the end of Bronze Age to nowadays [65–71].

The main preservation factor of the Valli Grandi Veronesi ancient landscape is due to the presence of an alluvial/marshy clay layer [65], which gradually had covered the whole area from the Early Middle Age to the Modern Age. The presence of this layer and the general low drainage had made the Valli Grandi Veronesi a swamp almost uninhabited until the end of the 19th century when the reclamations of the area began.

For these reasons, the Valli Grandi Veronesi represents an optimal context both for archaeological research and for non-invasive analysis as aerial photo interpretation, DTM data from LIDAR, and geophysical measurements.

The hydrographic network contemporary to Fondo Paviani Terramara mainly consisted of spring-fed rivers flowing through the Menago Valley [65,66]. The sedimentary contribution of these rivers started between the end of the Early Bronze Age and the central phases of the Middle Bronze Age (between the 17th and the 16th century BC), is also at the origin of the formation of the ridge where, about two centuries later, the Fondo Paviani settlement developed [65]. A spring-fed river and Perteghelle channel, a watercourse certainly active between the Late Pleistocene and the beginning of the Holocene surround the N–W and S–W sides of the site. Probably, the Perteghelle palaeo-channel was not wholly inactive contemporarily to the life cycle of Fondo Paviani, although carrying slight flows of water [67].

#### *2.2. Aerial Photograph Interpretation*

The analysis and the consequent interpretation of aerial photographs represented the first step of the whole research. The aerial photograph interpretation helps in the identification of some hypothetical anthropic structures and natural features of the buried landscape, allowing in the plan of the field investigation the direct or non-direct verification of these features.

Firstly, a broad photo set of the area of Fondo Paviani settlement and its nearest hinterland allow the identification of the aerial frames of interest. Six different years and four companies were selected: I.G.M.I. (Istituto Geografico Militare Italiano) and G.A.I. (Gruppo Aeronautico Italiano) 1955 flights, S.C.A.M.E. (Società Cartografica Aero Fotogrammetrica Meridionale di Scambia) 1983 flight, C.G.R. (Compagnia Generale Riprese aeree) 1990, 1999, and 2004 flights, and ROSSI (ROSSI s.r.l.) 1997 flight (Table 1). The details of each aerial shot are reported in Table 1. Different years and months were considered to analyze the same area in different seasonal and cultivation conditions (Table 1).

The high quality of the frames and the high visibility of the buried landscape reduce the processing to the enhancement and object classification steps [72,73]. The piece of evidence related to the archaeological and natural landscape features have been selected and compared, frame by frame, with different soil marks and crop marks [74]. A previous study of the Valli Grandi Veronesi landscape, based on aerial photo-interpretation [75], attributes light colors at features consisting of draining sediments (sand and coarse silt), often related to elevation structures, that can correspond to alluvial ridges or artificial ramparts, and dark colors at limited drainage areas and, more broadly, wetlands or fillings of abandoned water channels.

The aerial frames and the vector data of the photo interpretation were then loaded on Quantum GIS (release 2.18) and georeferenced. The contribution of GIS is essential to measure the features, to define their geometry better, and to determine their spatial relationships. Through GIS it was also possible to integrate the aerial photo interpretation with DTM data derived from LIDAR defining the geographical position of the features to plan further field investigations.
