remote sensing Article Remote Sensing, Archaeological, and Geophysical Data to Study the Terramare Settlements: The Case Study of Fondo Paviani (Northern Italy) Rita Deiana 1,* , David Vicenzutto 1, Gian Piero Deidda 2 , Jacopo Boaga 3 and Michele Cupitò 1 1 Department of Cultural Heritage, University of Padova, Piazza Capitaniato 7, 35139 Padova, Italy; [email protected] (D.V.); [email protected] (M.C.) 2 Department of Civil and Environmental Engineering and Architecture, University of Cagliari, Via Marengo 2, 09123 Cagliari, Italy; [email protected] 3 Department of Geosciences, University of Padova, Via Gradenigo 6, 35129 Padova, Italy; [email protected] * Correspondence: [email protected]; Received: 22 June 2020; Accepted: 6 August 2020; Published: 13 August 2020 Abstract: During the Middle and Recent Bronze Age, the Po Plain and, more broadly Northern Italy were populated by the so-called “Terramare”, embanked settlements, surrounded by a moat. The buried remains of these archaeological settlements are characterized by the presence of a system of palaeo-environments and a consequent natural gradient in soil moisture content. These differences in the soil are often firstly detectable on the surface during the seasonal variations, with aerial, satellite, and Laser Imaging Detection and Ranging (LIDAR) images, without any information on the lateral and in-depth extension of the related buried structures. The variation in the moisture content of soils is directly related to their differences in electrical conductivity. Electrical resistivity tomography (ERT) and frequency domain electromagnetic (FDEM), also known as electromagnetic induction (EMI) measurements, provide non-direct measurements of electrical conductivity in the soils, helping in the reconstruction of the geometry of different buried structures. This study presents the results of the multidisciplinary approach adopted to the study of the Terramare settlement of Fondo Paviani in Northern Italy. Remote sensing and archaeological data, collected over about 10 years, combined with more recent ERT and FDEM measurements, contributed to the analysis of this particular, not yet wholly investigated, archaeological site. The results obtained by the integrated multidisciplinary study here adopted, provide new useful, interesting information for the archaeologists also suggesting future strategies for new studies still to be conducted around this important settlement. Keywords: electrical resistivity tomography (ERT); frequency domain electromagnetic (FDEM); archaeology; terramare; bronze age 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 Remote Sens. 2020, 12, 2617; doi:10.3390/rs12162617 www.mdpi.com/journal/remotesensing Remote Sens. 2020, 12, 2617 2 of 21 Remote Sens. 2020, 12, x FOR PEER REVIEW 2 of 22 highlighted in the contexts in which the distribution of buried large natural or artificial systems must beartificial defined, systems extended must not be only defined laterally, extended but also not in-depth. only late Theoretically,rally but also in the-depth. penetration Theoretically, depth ofthe the electricalpenetration signal depth depends of the on electrical the total signal length depend of thes ERT on the line, total the powerlength source,of the ERT but line also, thethe electricalpower conductivitysource, but ofalso the the investigated electrical conductivity systems. The of use the of investigated ERT, often combinedsystems. T withhe use frequency-domain of ERT, often electromagneticcombined with (FDEM), frequency also-domain known aselectromagnetic electromagnetic (F inductanceDEM), also (EMI) known measurements, as electromagnetic is recently mostlyinductance documented (EMI) measurements, in agriculture, geomorphological,is recently mostly documented and sedimentary in agriculture research, geomorphologica applications [23–l37, ]. Bothand methods sedimentary are, in research fact, susceptible applications to the [2 di3–ff37erences]. Both inmethods electrical are, conductivity in fact, susceptibl of the soils,e tostrictly the relateddifferences to their in dielectricalfferentsoil conductivity moisture content.of the soils This, strictly capability related is fundamental,to their different for example,soil moisture in the content. This capability is fundamental, for example, in the identification of buried channels and identification of buried channels and corresponding palaeo-environments, or related structures, often corresponding palaeo-environments, or related structures, often also interesting from the also interesting from the archaeological point of view. The differences in the soil moisture content, archaeological point of view. The differences in the soil moisture content, existing between these existing between these buried structures and the hosting system, produce visible crop marks or surface buried structures and the hosting system, produce visible crop marks or surface evidence, identifiable evidence, identifiable by aerial and satellite images. In recent years, several scientific studies, both by aerial and satellite images. In recent years, several scientific studies, both in geological and in geological and archaeological contexts, moving from preliminary information collected by remote archaeological contexts, moving from preliminary information collected by remote sensing data, used sensinggeophysical data, usedprospection geophysical to define prospection these buried to define structures these [3 buried8–44]. T structureshis paper, [38considering–44]. This these paper, consideringpromising theserecent promising applications, recent shows applications, a multidisciplinary shows a multidisciplinaryapproach carried out approach to characterize carried outthe to characterizefortified system the fortified of Late systemBronze ofAge Late Terrama Bronzera Age settlement Terramara of Fondo settlement Paviani. of FondoThe term Paviani. “Terramara The term” “Terramara”identifies the identifies archaeological the archaeological remains of remains the fortified of the settlements fortified settlements diffused in di ffNorthernused in NorthernItaly, more Italy, morespecifically specifically in the in Po the Plain, Po Plain, between between the central the central phase phase of the of Middle the Middle Bronze Bronze Age and Age the and end the of endthe of theRecent Recent Br Bronzeonze Age Age (1600/1550 (1600/1550–1175–1175/1150/1150 BC) BC) [45 [,4546,]46. A]. palisade A palisade or ora rampart, a rampart, and and a wide a wide ditch ditch connectedconnected with with a watercoursea watercourse surrounded surrounded thethe TerramareTerramare (Figure 11).). FigureFigure 1. Reconstruction1. Reconstruction of aof Terramara a Terramara development development (Santa (Santa Rosa Rosa di Poviglio, di Poviglio, [47], modified[47], modified by authors). by (a)authors). Landscape (a) viewLandscape before view the settlement; before the ( bsettlement;)” Villaggio (b Piccolo”:)” Villaggio a little Piccolo settlement”: a little surrounded settlement by ditchsurrounded and palisade, by ditch later and destroyed palisade, later and covereddestroyed by and a rampart. covered by (c) a “Villaggio rampart. (c Grande”:) “Villaggio expansion Grande”: of theexpansion small village of the with small new village fortified with part new with fortified ditch part and with rampart. ditch (dand) Particular rampart. of(d) the Particular settlement of the at its maximumsettlement development, at its maximum when development, small and bigwhen villages small an coexisting.d big villages coexisting. AnAn intensive intensive agro-pastoral agro-pastoral economy economy characterizedcharacterized the the Terramare Terramare culture. culture. A Almostlmost every every site site was was surroundedsurrounded by by a vasta vast structured structured agrarian agrarian hinterlandhinterland with channeling channeling systems. systems. In In the the Middle Middle Bronze Bronze RemoteRemote Sens. Sens.2020 ,201220,, 2617 12, x FOR PEER REVIEW 3 of 223 of 21 Age, the social order of the communities was tribal, while in the Recent Bronze Age, it seems that the 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, social model was comparable to an evolved chiefdom [48–50]. At the end of the Recent Bronze Age, a generala general crisis, crisis, due due to demographic to demographic and and environmental environmental factors, involved involved Terramare Terramare Culture. Culture. In the In the SouthernSouthern Po Plain,Po Plain the, the crisis crisis led led to to a a full full abandonment abandonment of of the the settleme settlements,nts, while while in the in theNorthern Northern