Geophysical and Archaeological Characterization of a Modest Roman Villa: Methodological Considerations about Progressive Feedback Analyses in Sites with Low Geophysical Contrast

Abstract

The low contrast in physical properties of archaeological elements compared to the host soil is a common drawback in geophysical surveys applied to subtle archaeological sites because those contrasts are usually what are being measured by most instruments. Furthermore, when archaeological elements and construction remains are placed within the same package of materials, differentiation of each can make the interpretation of geophysical data sometimes difficult. In this work we propose a dynamic, integrated approach for the characterization of an archaeological site with simple Roman construction materials in order to evaluate methodological considerations in the evaluation of this kind of sites. This approach includes: (i) a preliminary evaluation of construction material characteristics, according to the background provided by the historical and geographical context and from previous excavations, (ii) measurements of magnetic susceptibility of archaeological and natural materials in the site for direct modelling of the expected anomalies; (iii) a geophysical survey including magnetometry, multifrequency electromagnetic (EM) method and ground penetrating radar (GPR) (100, 250 and 500 MHz centre frequency antennas); (iv) geophysical data evaluation for planning subsequent systematic surveys; (v) dynamic interpretation of geophysical results through careful data evaluation of all previous steps. The final archaeological model from geophysical data has been successful due to the manner of data interpretation looking for orthogonal patterns of geophysical anomalies that were hypothesized to be subsurface walls. Modelling was then followed by archaeological excavations consisting of three trenches where the walls were exposed. The integration of geophysical data with excavations has permitted to evaluate significance of the different geophysical analysis and to identify their archaeological meaning. The proposed sequential methodology represents an innovative manner of analysis (i) in subtle sites where construction remains are scarce and the absence of well‐defined geophysical contrasts can limit the results of usual surveys and (ii) to increase the efficiency in the evaluation of more extensive survey areas. Copyright © 2015 John Wiley & Sons, Ltd.

Magnetic Prospecting as a Tool for the Characterization of Mining Dams in the La Carolina Mining District (South of Spain)

“…In this sense, it is worth highlighting its great utility in mining and, specifically, in the prospecting of ferromagnetic elements [24][25][26][27]. In addition, it has been used to carry out geological mapping in heavily covered areas [28,29], hydrocarbon prospecting sites [30], archaeological prospecting sites [31,32], and location of sinkholes or shallow holes [10,33,34]. However, to date, it has not been used for the characterization of mining dams.…”

GPR and Magnetic Techniques to Locate Ancient Mining Galleries (Linares, Southeast Spain)

“…GPR prospecting method has been widely used in geoscience studies, including studies focused on surface geology, hydrology, mining, environment, forensics, and archaeological or heritage studies [7,15,17,18]. In this sense, Cardarelli et al [19] applied this technique successfully in civil engineering to evaluate the rock fracturing and obsolescence of the concrete lining in a tunnel.…”

“…This technique does not require diurnal corrections because the two sensors are equally affected by the external magnetic field, which is one of the main advantages of this technique. Gradiometer measurements highlight shallow anomalies; that is, they are less sensitive to deep anomalies, thus opening new applications such as doline or karstic cavity detection [7,22], archaeological prospection [18,31], environmental studies [32], and detection of unexploded ordnance in military zones [33].…”

Investigation of Jabung Temple Subsurface at Probolinggo, Indonesia Using Resistivity and Geomagnetic Methods

“…Geopysical methods are used for idetification of landslide, mineral distribution, groundwater, geothermal, seepage zones, petroleum distribution, seawater intrusion, and archaeological traces [1]- [7]. The geophysical method is due its ability to determine the archaeological remains buried and provide information in the form of archaeological structure based on data in the form of resistivity, magnetic anomalies and other physical parameters [7]- [10]. Resistivity and magnetic methods have been developed gradually over the last 50 years to discover hidden objects and are now accepted as effective approaches to archaeological research [8] Some researchers have conducted research using magnetic, electromagnetic and resistivity methods to predict archaeological remains.…”