An analysis of the archaeological site of Pelusium on the northeastern edge of the Nile Delta, Egypt, was carried out using phased array type L-band synthetic aperture radar (PALSAR) data. The aim was to assess the potential of PALSAR to identify buried archaeological structures. The 18 PALSAR images acquired in various polarimetric modes were obtained for the analysis through a European Space Agency Category-1 project. Processing included co-registration and summation of images for each polarimetric mode in order to reduce speckle. The summed images were then compared with each other and with optical imagery to identify any features that may be of archaeological interest. Features identified on the summed images were also viewed in the individual images to assess their ephemeral nature. One image was available in quadrupole polarization (quad-pol) mode with which polarimetric analysis was undertaken, including extraction of target decompositions and analysis of the scattering characteristics of the study area. Linear and geometric features that may be archaeological structures were visible in the processed SAR imagery. Possible palaeolandscape features were also identified. Some of these are visible in the optical imagery, but not clearly delineated. The results of the polarimetric analysis show that single-bounce scattering dominates over the study area, and that over the sandy regions the signal is much weaker in all polarizations, with mixed scattering. Although the spatial resolution did not enable clear identification and characterization of the physical scattering properties of small-scale features, the PALSAR data demonstrate a capability to highlight features that become almost invisible in optical imagery at the synoptic scale (even if they are visible up close) leading to the conclusion that PALSAR may be a useful tool in the first stages of archaeological surveys to analyse the spatial pattern of features, and identify where to focus smaller scale surveys in areas with land cover similar to that of the study area. Copyright © 2013 John Wiley & Sons, Ltd.

SubSAR is a new scheme for mapping subsurface features with synthetic aperture radar (SAR) at large stand-off distances applicable to airborne and satellite measurements. This is in sharp contrast to current techniques, where discrimination relies on close-proximity measurement of the scene, usually with a ground-based system. The scheme discriminates between surface and subsurface returns using a novel application of differential SAR interferometry (DInSAR). It is based on the differing phase histories of surface and subsurface features. Whereas the latter experiences phase delays in sympathy with variations in soil moisture, these are absent from the surface feature's phase history. To assess the predictions and performance of the model against measurements, a laboratory investigation was carried out at the GB-SAR Microwave Measurement Facility. C-band VV tomographic profiling (TP) was collected of a trihedral and a pile of cobble stones, buried in a sandy soil. The TP imagery displayed the vertical backscattering pattern through the soil, allowing separation of returns from the soil and buried features. Known amounts of water were added incrementally to the soil to precisely quantify DInSAR phase and backscatter behaviours of the soil and buried features. The measurements confirmed the two central tenets of the model: (i) a linear relationship between soil moisture and DInSAR phase, and (ii) that this is independent of incidence angle. Application and performance of the scheme applied to mapping subsurface archaeology is discussed. A low-level product would deliver a basic distinction between surface and subsurface features in SAR imagery. The high-level product, with supporting ground-truth data, could additionally deliver the depth of a feature. Copyright © 2013 John Wiley & Sons, Ltd.

The aim of the present work was to compare Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) with RADARSAT-2 C-band satellite in order to identify the most suitable method for the detection of ground anomalies due to the presence of shallow underground archaeological structures. This comparison was performed over two UNESCO archaeological sites: Djebel Barkal (northern province of Meroe, Sudan) and Samarra (130 km north of Bagdad, Iraq). The choice of these two cultural sites was motivated by their position in a desert area (especially the Djebel Barkal site) where soil moisture has smaller impact on radar wave penetration, thus not compromising data interpretation. The largest difference between the satellites is the spatial resolution, around 20 m for the PALSAR sensor and 9 m for the RADARSAT-2 satellite. Given the importance of spatial resolution for archaeological purposes, that difference is balanced by the wave band utilized, which can be translated in differences in soil penetration. However, the quite superficial remains in both the sites give different but complementary responses. Polarimetric SAR data were analysed with PolSARpro software, and all the products were then compared with archaeological maps and available optical satellite images, used as a basis for the georeferencing process. This work constitutes a fundamental step in archaeological research toward a correct interpretation of all the scattering mechanisms above or around ancient structures. Additional information, such as meteorological conditions where available and archaeological maps (that can be consulted from the UNESCO website), was used as a support for interpretation of the archaeological areas; in the case of the Iraqi city of Samarra and of the archaeological area of Gebel Barkal, ground-truth surveys in situ are not allowed for political reasons. Copyright © 2013 John Wiley & Sons, Ltd.

The launch of the first German radar satellite TerraSAR-X in 2007 opened a new era in spaceborne radar remote sensing. So far the applicability for the high-resolution prospection of upstanding and, especially, buried monuments was limited because of the low resolution of the former sensors. TerraSAR-X, however, provides us with images with a spatial resolution of up to 1 m. The satellite operates in the so-called X-band with a frequency of 9.65 GHz. Therefore it is supposed that there is no possibility to penetrate the soil with this sensor. To testify and analyse the benefit of TerraSAR-X in archaeological geophysics, we chose as a test site a Roman fortress in Syria. The site was chosen as we already have GPR data of the same area for a comparison and for the verification of the actual penetration depth. Our results revealed that it is possible to resolve superficial and even buried structures in the data set, which provides evidence that the X-band waves can penetrate the soil. This paper shows our results of the survey and an estimation of the possible penetration depth of TerraSAR-X. Copyright © 2013 John Wiley & Sons, Ltd.

The ruins of the St Catherine's monastery complex, the largest sacral ruins in Slovakia, are an important example of Slovak cultural heritage. The Franciscan monastery was a famous site of religious significance due to the legends describing the apparitions of St Catherine. The preservation project of the monastery remains started in 1994. As a part of this project, complex historical, archaeological, anthropological and geophysical research has been conducted at the site since 1997. Microgravity and ground-penetrating radar (GPR) surveys were carried out in the nave of the former church in order to reveal the position of three aristocratic crypts that served as burial places for the members or higher society in the seventeenth and eighteenth centuries. In the microgravity data processing, a novel method for the calculation of the building correction was employed, where the gravitational effect of the church is calculated using a polyhedral model of the building created from photographs with a special photogrammetric software. Several gravity anomalies were found in the residual Bouguer anomaly map. Semi-automated interpretation techniques including the Euler deconvolution and harmonic inversion have been used to investigate the depth and size of anomalous sources. Results from 36 GPR profiles obtained by a 400 MHz antenna were visualized in the form of horizontal time-slices and vertical time-sections. These images indicate anomalous reflections suggesting potential archaeological targets. Integrated interpretation of results from both geophysical methods has confirmed the presence of a known aristocratic crypt excavated in 2001, as well as two other crypts predicted from historical archives. The combination of microgravity and GPR surveys has proved to be a very effective and non-destructive tool for archaeological research. Copyright © 2013 John Wiley & Sons, Ltd.

Different human activities produce different material signatures, and therefore integrating several complementary prospection data sets provides a more comprehensive picture of site structure than any one method. We combine magnetic prospection data with soil chemistry and surface collection data from two small late Neolithic (ca. 5000 bc) settlements in eastern Hungary. Magnetic gradiometer survey helps to define basic subsurface features. Semi-quantitative soil phosphate analysis improves our understanding of vertical and horizontal settlement boundaries and the locations of some activity zones. Through the surface distribution of burnt daub and pottery, controlled surface collection aids in our interpretations of structure and preservation at these settlements, as well as providing dating evidence. Spatial analysis, including the interpolation of chemical data, is performed in a geographical information system. Results indicate two different settlement types at contemporaneous sites, and suggest excellent preservation for site types that are poorly understood, relatively rare and generally poorly preserved in the archaeological record of eastern Hungary. In addition, this work provides the first comprehensive depiction of spatial organization at small late Neolithic settlements in the region. Copyright © 2013 John Wiley & Sons, Ltd.

During the Bronze Age, the region of La Mancha Occidental (Spain) was occupied by prehistoric settlements in which the protection of basic resources was a primary concern. The structure of these settlements comprised several concentric walls that surrounded conical mounds around 4–10 m high. The Motilla de la Vega is an unexcavated site next to the Azuer River, and is only 4 km from another Bronze Age village, called Motilla del Azuer, which has been subject to systematic archaeological excavations and is the paradigmatic reference for these settlements. As Motilla del Azuer had a well inside its walls and this fort is located in a similar geological setting, it is logical to ask whether Motilla de la Vega also had a well inside its walls, and to determine whether it is possible to extend similar architectonic and social patterns to other settlements that occupied the river valleys of this region. In this study, we used the electrical resistivity tomography (ERT) method to detect the possible location of a well in Motilla de la Vega. In order to plan appropriate data acquisition, and to evaluate the optimal parameters for processing the field data, we performed a numerical modelling exercise to simulate the likely ERT responses based on the geological information and on the constructive scheme of the excavated well in Motilla del Azuer. Afterwards, we carried out five ERT profiles over the levelled Motilla de la Vega site and some of them have resistive anomalies similar to those that synthetic models predict for a well. Consequently, we propose the existence of a well placed in the eastern side of Motilla de la Vega, with the same relative position as the well of Motilla del Azuer. This has implications for the understanding of other sites in the region. Copyright © 2013 John Wiley & Sons, Ltd.

Seismic tomography and ground-penetrating radar (GPR) were combined to determine weakness zones and the degree of alteration in rock making up the Moai statues of Easter Island. The surveys were carried out on stratified argillaceous tuff that had been subjected to weathering for long periods. The argillaceous nature and unsaturated condition of the rock creates ambiguity in both the seismic and georadar data interpretation, but this ambiguity is removed by using a combined interpretation of the data. Interpretation of the combined data shows that the high seismic velocities of the inner zones of the statues must be related to water content and not to better rock quality, because of the high attenuation of the georadar signal in those zones. The weathered zone is characterized by a high signal-to-noise ratio of georadar data and low P-wave seismic velocities. Comparing the seismic and GPR data sets, we found that the seismic velocity and the signal attenuation of the georadar section differ for two statues in accordance with the degree of alteration of the rock. We show that the combined interpretation of seismic and georadar data allows the removal of the ambiguities in the interpretation of the seismic velocity in the massive tuff, the definition of the thickness of the weathered layer and the linking of seismic velocity to the degree of Moai preservation, which is useful for a classification of Moai health. Copyright © 2013 John Wiley & Sons, Ltd.

The prospection and evaluation of former battlefields of the Great War or the First World War (WW I) poses specific challenges. For several reasons, large-scale excavation campaigns of this conflict landscape are problematic. The vastness of the former Western Front (one of the largest archaeological sites in the world), the large amounts of buried unexploded ordnance and the possible presence of human remains hinder invasive practices. As an alternative, an integrated approach combining a geophysical survey, contemporary aerial photographs and a topographic model is proposed. This approach was evaluated for a 3.2 ha WW I battlefield using a multireceiver electromagnetic induction (EMI) sensor. Integrating multiple apparent electrical conductivity (ECa) and apparent magnetic susceptibility (MSa) EMI measurements allowed evaluation of the present WW I remains in the subsoil, while comparison with WW I aerial photographs and a digital terrain model led to a comprehensive understanding of the WW I landscape. It is suggested that this approach may be of value for the investigation of battlefields in other locations and periods. Copyright © 2013 John Wiley & Sons, Ltd.

Ground-penetrating mapping radar allows for the three-dimensional reconstruction of ancient landscapes by interpreting geological horizons associated with archaeological sites. When the geological framework of a site can be placed in both time and space, ancient environments and people's usage and adaptation to landscapes can be studied. In coastal Portugal late Ice Age people discarded stone tools within aeolian sands that were deposited directly on a bedrock surface, which could be mapped using ground-penetrating radar. That surface was then studied in three-dimensions and the palaeotopography at the time people were using this area was mapped. It was found that these ancient people probably took shelter behind a small elevation rise on the edge of a series of streams that flowed toward a nearby floodplain. Using this type of analysis the environmental context of prehistoric activities and human behaviour of these people is provided in a way not possible using traditional archaeological methods. Copyright © 2013 John Wiley & Sons, Ltd.

Strong archaeological evidence exists for the presence of Anglo-Saxon settlement at the former Roman civitas capital Venta Icenorum, including two cemeteries of early Saxon date. A large-scale magnetic survey west of the former walled town has revealed a complex palimpsest of surviving subsurface features, several of which were cautiously interpreted as the remains of Anglo-Saxon sunken-featured buildings (SFBs). Targeted earth resistance measurements enhanced the interpretation in terms of likely subsurface morphology. One of these anomalies was subsequently subject to archaeological excavation, revealing the surviving remains of an SFB of middle Saxon date. The magnetic susceptibility of deposits sampled during excavation was also evaluated and a simple forward model constructed to compare a theoretical magnetic response of the structure to that observed in the field. A reasonable correlation was observed, allowing the quantitative characterization of similar magnetic anomalies revealed in the survey data. Copyright © 2013 John Wiley & Sons, Ltd.

Tools for the processing of raster data are well developed, but noisy data still pose considerable challenges. If anomalies are broken up into isolated individual readings, for example due to high noise levels, it may still be possible for a human interpreter to recognize the isolated readings as being part of a single anomaly. However, such a concept of neighbourhood is difficult to implement with raster tools and an alternative, vector-based approach is presented here. By converting the measured raster data into polygons, it is possible to undertake shape and neighbourhood analysis to process the data. This allows discriminating, reshaping and merging of the anomalies based on their spatial location relative to each other (neighbourhood) and with respect to the size of each anomaly. The added advantage of this approach is the possibility to use the processed vector data as a basis for interpretation and visualization diagrams in two- and three dimensions. This method is applied to the GPR survey of a necropolis at Pessinus, showing several types of grave monuments. Copyright © 2013 John Wiley & Sons, Ltd.