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Continuing advances within unmanned aerial vehicles and scalar magnetic sensor technology are revolutionizing geophysical remote sensing. For perspective, examples of high resolution, low noise data presented in this study enabled detection and accurate positioning of human-made objects ferrous objects with a total mass of 0.5 kg, from altitudes around and above 2 m. However, with these new possibilities come a requirement of higher fidelity, where good sensor position estimates in particular are key to achieving a data quality sufficient for reliable data interpretation and geophysical inversion. Apart from inherent instrument properties, typical factors that hamper sensor position estimation are lag and parallax errors. Lag errors arise from time-stamping delays between the positioning system and sensor reading, while parallax errors stem from the imperfect recovery of sensor positions due to a decoupling and/or distancing of the positioning system and sensor head. The impact from each of these error sources is typically similar and partially or even completely inseparable. A number of correctional techniques exist, typically based on large-scale data correlations, or collection of specific additional data. We present a survey data adjustment method based on the simultaneous inversion of source parameters and a number of independent survey shifts or lags in pre-specified sections of a survey. The method is particularly suited for surveys where the sensor path through space can be assumed well known, but the sensor position itself may suffer lags or shifts relative to the position measurement. The approach is based on modelling an existing source signature within the data and requires no data transformations, such as continuation to a two-dimensional plane, or enforcing of smoothness. The approach is an amendment to independent source inversion and is ideal for scenarios where the source behaviour is thought to be well known, such as processing efforts in which the objective is source–parameter inversion. In this study, we validate the approach using a simple point-dipole model to adjust synthetic data and subsequently demonstrate it on an unmanned airborne scalar magnetic survey for small unexploded ordnance targets, where a hardware malfunction resulted in unknown time-shifts between magnetic sensor readings and positioning unit output. The adjustment procedure was carried out on line data, based on a single anomaly from a 155 mm shell, and enabled the recovery of signatures from several other ferrous unexploded ordnance targets as small as 0.5 kg. Subsequent inversion on the corrected signatures provided unexploded ordnance positions with an accuracy suitable for recovery purposes.

Early medieval strongholds are a significant phenomenon in the archaeology of East Central Europe, as they mirror the political and socio-economic changes occurring towards the end of the Early Middle Ages. This contribution is concerned with the site of Břeclav-Pohansko (Czech Republic), which graphically illustrates the rise and fall of the Moravian principality during its short existence from the second half of the 9th to the beginning of the 10th century. The site has been systematically excavated over more than 60 years. The excavation work has been accompanied by numerous geophysical surveys. Based on comparing previous knowledge of settlement on the site and the results of magnetic prospection, we evaluated similarities and differences in the central district of the stronghold using statistics and spatial analysis. Upon analysis of the success rate of the applied geophysical method, we present the resulting model of the settlement structure. The results confirm that the structure of the builtup area in the central district at Pohansko follows an original pattern which has no analogues in the Central Danubian region in the given period.

Magnetic measurements with an unmanned aerial vehicle are ideal for filling the gap between ground and airborne magnetic surveying. However, to obtain accurate aeromagnetic data, the compensation of magnetic effects of the unmanned aerial vehicle is a challenge. Typically, scalar magnetometers are towed several metres under the unmanned aerial vehicle to minimize its magnetic field. In this study, a fluxgate three‐component magnetometer is attached 42 cm in front of the unmanned aerial vehicle at the tip of a composite pipe. Using a scalar calibration, the sensor can be calibrated, and the permanent and induced magnetic fields of the unmanned aerial vehicle can be compensated. The contributions of the magnetic measurements at different altitudes to the unmanned aerial vehicle results were tested over an area of 1 km² in the Northern Vosges Mountains. The area is located in a hamlet surrounded by a forest where few geological outcrops are observed. Three magnetic surveys of the same area are obtained at different altitudes: 100, 30 and 1 m above the ground. The unmanned aerial vehicle magnetic data are compared with a helicopter aeromagnetic survey at 300 m above the ground and a ground magnetic survey using upward continuations of the maps to compare the results. The magnetic maps (300, 100, 30 and 1 m above the ground) show very different magnetic anomaly patterns (e.g. amplitude, shape, wavelength and orientation). The magnetic data at different altitudes improve the understanding of the geology from the local to more general scales.

Optically pumped vapour magnetometers have an orientation dependency in measuring the scalar component of the ambient magnetic field which leads to challenges for integration with mobile platforms. Quantifying the three‐dimensional attitude variations (yaw, pitch and roll) of an optically pumped vapour magnetometer, while in‐flight and suspended underneath a rotary unmanned aerial vehicle, aids in the successful development of reliable, high‐resolution unmanned aerial vehicle magnetometry surveys. This study investigates the in‐flight three‐dimensional attitude characteristics of a GEM Systems Inc. GSMP‐35U potassium vapour magnetometer suspended 3 m underneath a Da‐Jiāng Innovations S900 multi‐rotor unmanned aerial vehicle. A series of unmanned aerial vehicle‐borne attitude surveys quantified the three‐dimensional attitude variations that a simulated magnetometer payload experienced while freely (or semi‐rigidly) suspended underneath the unmanned aerial vehicle in fair weather. Analysis of the compiled yaw, pitch and roll data resulted in the design of a specialized semi‐rigid magnetometer mount, implemented to limit magnetometer rotation about the yaw axis. A subsequent unmanned aerial vehicle‐borne magnetic survey applying this specialized mount resulted in more than 99% of gathered GSMP‐35U magnetic data being within industry standards. Overall, this study validates that maintaining magnetometer attitude variations within quantified limits (±5° yaw, ±10° pitch and roll) during flight can yield reliable, continuous and high‐resolution unmanned aerial vehicle‐borne magnetic measurements.

Recent advancements in geophysical exploration have been realized through reliably integrating unmanned aerial vehicle platforms with lightweight, high‐resolution magnetometer payloads. Unmanned aerial vehicle aeromagnetic surveys can provide a contemporary data product between the two end‐members of coverage and resolution attained using manned airborne and terrestrial magnetic surveys. This new data product is achievable because unmanned aerial vehicle platforms can safely traverse with magnetometer payloads at flight elevations closer to ground targets than manned airborne surveys, while also delivering an increased coverage rate compared to walking conventional terrestrial surveys. This is a promising new development for geophysical and mineral exploration applications, especially in variable terrains. A three‐dimensional unmanned aerial vehicle aeromagnetic survey was conducted within the Shebandowan Greenstone Belt, northwest of Thunder Bay, Ontario, Canada, in July 2017. A series of two‐dimensional grids (∼500 m × 700 m) were flown at approximate elevations of 35, 45 and 70 m above ground level using a Da‐Jiāng Innovations multi‐rotor unmanned aerial vehicle (S900) and a GEM Systems, Inc., Potassium Vapour Magnetometer (GSMP‐35U). In total, over 48 line‐km of unmanned aerial vehicle aeromagnetic data were flown with a line spacing of 25 m. The collected aeromagnetic data were compared to a regional heliborne aeromagnetic survey flown at an elevation of approximately 85 m above the terrain, with a line spacing of 100 m, as well as a follow‐up terrestrial magnetic survey. The first vertical derivative of the gathered unmanned aerial vehicle total magnetic field data was calculated both directly between each of the different flight elevations, and indirectly by calculating the values predicted using upward continuation. This case study demonstrates that low flight elevation unmanned aerial vehicle aeromagnetic surveys can reliably collect industry standard total magnetic field measurements at an increased resolution when compared to manned airborne magnetic surveys. The enhanced interpretation potential provided by this approach also aided in delineating structural controls and hydrothermal fluid migration pathways (a pair of adjacent shear zones) related to gold mineralization on site. These structural features were not clearly resolved in the regional manned airborne magnetic data alone, further demonstrating the utility of applying high‐resolution unmanned aerial vehicle aeromagnetic surveys to mineral exploration applications. The conclusions and interpretations drawn from the unmanned aerial vehicle aeromagnetic data, coupled with historical data, were applied to make a new gold mineralization discovery on the site, assayed at 15.7 g/t.

This article focusses on an original magnetic survey protocol and its data processing chain. The use of a high sensitive magnetometer combined with a motorized total station permits production of a magnetic map with a high spatial resolution and a high precision of magnetic and positional measurements. The data processing enhances the final magnetic map by the removal and restoring the outlier values, measurement errors and magnetic disturbances. The magnetic survey was undertaken on the Neolithic site of Le Pontet at Saint-Nazaire-sur-Charente (French Atlantic coast, between Bordeaux and La Rochelle). The site was chosen for geographical and archaeological characteristics such as its settlement period, the topography and the presence of different magnetic disturbances (proximity to roads and residential area). The data processing is mainly made on ungridded data and the gridding is the second to last step. The last step is to correct the relative height variation of the sensors between the prospecting lines (tracks) induced by the topography and operators. The use of a motorized total station allows accurate height determination of the sensors and an upward continuation is performed to correct the slight magnetic intensity variation induced by the relative height variation of the sensors. The results of the magnetic map bring out several causewayed enclosures, pits and postholes. This map will serve as a working basis for interdisciplinary studies and future archaeological studies of this site.

Ground-based detailed magnetic surveys have so far been minimally used in permafrost research but they have a great potential to explore near-surface structures and to reveal their hidden features. This study presents the results of a two-elevation magnetic survey on a Pleistocene ice complex covered by Holocene deposits and penetrated by ice wedges. A polygonal pattern, which is not distinctly visible on the surface, is successfully identified in the anomalous magnetic field. Obtained data allow to confidently allocate polygon distribution and to discriminate ice wedges of different thicknesses. Typical values of total magnetic field anomalies related to ice wedges and frozen sediments in between are about several nanoteslas measured at the elevations of 0.4 and 1.15 m above the surface. Magnetic susceptibility of permafrost samples is of the order of 10-4. Observed data were modelled using a numerical magnetic model to estimate quantitatively geometrical and magnetic parameters of the ice complex structure. The best fitting model provides the following results: the upper part of Pleistocene and Holocene ice wedges shows a thickness of 8 and 3 m, respectively, and the upper boundary of the Pleistocene ice wedges where they contact with Holocene wedges rests at 1 m depth. The magnetic susceptibility of frozen sediments between ice wedges is about 0.14 × 10-3. An anomalous high vertical gradient within the study area has been observed. The presumable sources for this anomaly sources were considered. Our results suggest that detailed magnetometry could be efficient as it is a rapid and non-invasive reconnaissance permafrost research.

Significant near-surface magnetic distortions and weakly magnetic responses complicate the interpretation of surface magnetic data and compound difficulties associated with the prospecting of deepburied orebodies in old mines, such as the Daye iron-ore deposit. To address this problem, we used three-component borehole magnetic measurements from multiple drillholes to evaluate a magnetisation inversion approach that incorporates these data to obtain magnetisation intensity distributions. The magnetisation direction was estimated from rock and ore sample magnetic property measurements. Linear optimisation problem equations were solved using the pre-conditioned conjugate gradient algorithm. Tests on two-dimensional synthetic data returned favourable results. In the case study of the Daye iron-ore deposit, several concealed magnetite orebodies were discovered using three-component borehole magnetic measurements. Two-dimensional magnetisation inversion for borehole magnetic data indicated that magnetic sources were located at the contact zones between the diorite and marble rocks, as verified by other drillings. A three-component borehole magnetic survey shows advantages of moving away from shallow interferences and containing important additional information compared with a surface total field and provides a feasible approach to explore deep-buried and concealed minerals in areas with strong near-surface distortions.

Fluxgate 3-axis magnetometers are seldom used on archaeological sites due to their lack of precision. Nonetheless, they offer light weight, low power consumption and the ability of compensation of the magnetization of the prospecting device. This study proposes to use calibration and compensation processes developed for space research and aerial measurement to build a multi-sensor and georeferenced device to assess deep and shallow objects for large-scale archaeological investigations in Qasr 'Allam, in a context of heavy sedimentary coverage and uneven surface. The use of the device on the site in combination with potential field transformations of the signal such as the double reduction to the pole and the vertical derivative reveal a vast irrigation system as well as a large religious facility. A comparison with gradiometric measurements shows a resolution as good at least for shallow sources. The precise positioning allows targeted excavations that validate the geophysical interpretations and offer new archaeological information. These discoveries give enough proof to the local authorities to define the area to be protected from the threatening progression of agricultural fields. Copyright © 2016 John Wiley & Sons, Ltd.

Archaeological remains are very often buried under uneven soil of agricultural fields crossed by rather parallel furrows and ridges. Consequently, ploughing in a magnetic survey might produce a repetitive, quite regular, linear noise in the data, which could impede optimal recovery of the archaeological magnetic anomalies; depending on the acquisition line orientation, this noise may show as an oblique, vertical or horizontal pattern in the magnetic maps. Several studies have tested and verified methods for oblique ploughing minimization, but, to our knowledge, no procedures regarding the vertical and horizontal types of noise have been published. The present research proposes a procedure to filter each type of ploughing effect through an algorithm working in the wavenumber domain. The procedure produces images with a considerable reduction of the noise in any direction, resulting in enhanced visibility and readability of the archaeological anomalies. Copyright © 2016 John Wiley & Sons, Ltd.

Irrespective of the region and time period, settlement pits are common features at archaeological sites. Variations in shape, size and fill reflect great diversity in terms of primary and secondary functions. Careful analysis of these aspects and a pit's refilling history yield key information for the reconstruction of economic, social and chronological aspects of settlement history. At present, it is unusual for a settlement site to undergo complete excavation; in most cases, only small areas within a larger settlement are opened to archaeological inquiry and, accordingly, only a scarce few pits can be excavated. Therefore, the application of a combination of new prospection methods can help to classify and preselect representative pits for subsequent excavation in order to guarantee the highest information output. The interdisciplinary investigations at the Early Bronze Age of Fidvar in Slovakia enabled the development of just such a multidimensional research strategy for the evaluation of settlement pits. Used in concert, magnetic survey and electromagnetic prospection delivered 2D data which revealed the locations of pits at the site. This was the basis for the 3D electrical resistivity tomography measurements which followed, enabling the three-dimensional reconstruction of prehistoric pits' geometries. Supplementary sedimentological and geochemical investigations of the pits' contents revealed important information about the pits' former functions as well as the mechanisms of the processes through which they were filled in. Thus, the integrated approach provides us with a new means of obtaining an overview of pit assemblages at archaeological sites in general and demonstrates its potential for the acquisition of valuable information about the food acquisition and storage processes at Fidvar in specific. Copyright (C) 2015 John Wiley & Sons, Ltd.

Relatively few geophysical surveys have shown how buried traces of agricultural fields can be revealed. An ancient Greek vineyard on the Crimean peninsula was first suggested in a satellite photograph; however, it was discovered only with a magnetic survey. This survey found a 5.7-ha field that is crossed by about 80 buried stone walls that are parallel and spaced by 2.6 m; this pattern is found only in the vineyard. Later excavations revealed underground walls in this vineyard. The magnetic survey also detected simple magnetic anomalies at three of the four corners of the vineyard. Excavations found that these anomalies are caused by pits that were dug by the ancient Greeks into bedrock to a depth of 2.5 m; the purpose of these pits is not known. The magnetic properties of soil and stone were measured in the excavations, and the magnetic anomalies of the features were calculated. These calculations agree with the measurements, and this means that the entire source of the anomalies was discovered. The interpretation of the magnetic map was adaptive, and it improved as excavations added more information. The archaeological importance of the Ortli vineyard is described along with the efficient procedures that allowed its discovery and mapping. Using the same techniques that were applied at Ortli, another ancient Greek vineyard and farmhouse was later found 1.5 km away. This vineyard has dimensions that are 25% larger than those of the first vineyard. Copyright © 2015 John Wiley & Sons, Ltd.

A non-invasive investigation, integrating aerial photography and high-resolution magnetic survey, was carried out at the Masseria Pantano site (Apulia, Southern Italy) to obtain a more detailed reconstruction of an extensive ancient settlement, which revealed different phases of human frequentation. The results of the ground-based survey were also used to guide some archaeological excavations, which brought to light, mainly, parts of Medieval wall and column foundations. The correlation between the magnetic anomalies and archaeological remains was very satisfying, except for the lack of a source body that could explain the origin of a positive anomaly, the intensity and extent of which is very significant. A supplementary magnetic survey combined with stratigraphic interpretation from two boreholes, followed by susceptibility measurements, were able to solve this interesting partial misunderstanding between archaeological and magnetic data. This approach revealed clear evidence for a canal, probably Roman in date, which lies beneath the presumed ancient surface identified during the excavation. Copyright © 2014 John Wiley & Sons, Ltd.

Magnetic survey is one of a number of methods used in archaeological geophysics for detecting and mapping archaeological artefacts and features. Recent magnetic instruments have become both faster and more sensitive as a result of technological and industrial developments. Hence, magnetic methods are becoming an accepted part of archaeological projects. Mapping the edges of magnetic sources is a problem of fundamental importance in magnetic interpretation. Commonly used edge-detection filters are considerably affected by the presence of noise because this requires the computation of horizontal and vertical derivatives of the magnetic data. Archaeomagnetic data are often dominated by large-amplitude anomalies that mostly originate from the presence of noise and other environmental effects. Prior to application of the edge-detection filters, an upward continuation of the archaeomagnetic anomaly or low-pass filtering may be used to reduce environmental effects. Another useful approach is to apply edge-detection filters to the pseudogravity-transformed data. This paper compares the results of common edge-detection filters applied to the original and pseudogravity-transformed archaeomagnetic data. In the concept of edge detection, the feasibility and capability of the pseudogravity transformation is demonstrated using a real archaeomagnetic dataset from the ancient city of Pisidia Antiocheia in the province of Isparta (central part of Turkey). Copyright © 2014 John Wiley & Sons, Ltd.

The archaeological site of El Cano is located in the cultural region of Gran Cocle and is one of the most important pre- Columbian ceremonial complexes of the Isthmus of Panama. El Cano is 3.57ha in area presents a set of mounds and alignment of columns of carved basalt and tuff. The first organized occupation is dated between 100 and 400 BC, and this occupation lasted until the arrival of the Spanish conquerors. In order to determine the spatiotemporal organization of the site, the first magnetic and electrical surveys of this archaeological site were performed in 2005 and 2006. Although the resistivity mapping survey did not offer any information about buried stone structures, the magnetic survey in gradiometer mode produced well-characterized magnetic anomalies. A circular magnetic anomaly in the central area of the site allowed the discovery of one of the largest Panamanian pre-Columbian funerary complexes. Copyright © 2014 John Wiley & Sons, Ltd.

Several studies in the field of archaeological prospection have suggested that multi-element soil geochemical survey holds potential as an archaeological survey method, complementing more common techniques such as magnetometry and fieldwalking. Despite this, only limited research regarding this topic has been carried out. In this study, a geochemical survey was conducted in the Eastern Suburbium of the Roman to Byzantine city of Sagalassos, with the aim of investigating the possibilities and limitations of the technique in facilitating the interpretation of magnetic survey data. To explore the multivariate patterns present within the chemical dataset, the data were statistically analysed using a contiguity-constrained spatial clustering algorithm. The resulting spatial clusters revealed that an area characterized by high-frequency magnetic anomalies was spatially associated with a chemical cluster rich in Cu, K, P, Pb and Zn. This is interpreted as resulting from the accumulation and decomposition of occupational debris. Enhancements of Al, As and Ba helped to interpret an area with a low magnetic signal as a region where limestone bedrock was located close to the soil surface. Finally, two zones of enhanced magnetization were shown to spatially overlap with two clusters of soils containing elevated levels of Co, Cr, Mg, Mn, Ni and (Fe) and Ti, V and (Fe), respectively, indicating the presence of two different types of mafic to ultramafic ophiolitic bedrock near the soil surface. This study confirms that multi-element geochemistry has potential as a survey technique, because it offers direct information on soil bedrock or ancient human disturbance, thereby adding an extra dimension to the interpretation of geophysical survey data. It is shown that soil chemical data are particularly valuable for distinguishing anthropogenic and natural impacts creating geophysical anomalies. Contiguity-constrained clustering was found to be a promising data analysis technique for multivariate geochemical survey data. Copyright © 2013 John Wiley & Sons, Ltd.

Population estimates are a vital backdrop to our understanding of ancient societies' socio-economic structures and development. In order to facilitate such an informational mise en scene in terms of the early Bronze Age settlement of Fidvar in southwestern Slovakia, a new geophysical–geochemical approach is presented here, the first results of which are very promising. The crux of the new methodology utilizes the population's chemical fingerprint in relation to total anthropogenic phosphorus input as a proxy for different population models. These methods suggest an early Bronze Age population of 300–600 individuals, in accordance with the comparative analysis of a magnetic survey, and also matches initial archaeological estimates. Further methodological adjustments suggest an even higher population of up to 1000 inhabitants. In light of these figures, it is likely that Fidvar was one of the centres of the early Bronze Age socio-economic system of the northern Pannonian Basin. Copyright © 2013 John Wiley & Sons, Ltd.

This paper presents the results of a multisystem survey using magnetometry and dual frequency ground-penetrating radar (GPR) carried out at the Iron Age Iberian site of El Moli d'Espigol, Tornabous, Catalonia, dated from the seventh to third centuries bce. The surroundings of the current urban area were explored with magnetometry in order to describe possible features related to the settlement. In the non-excavated part of the urban area was surveyed by GPR in order to describe the urban mesh. The interpretation of the data has allowed not only the identification of new areas of archaeological interest and priority action, but also the proposal of a new hypotheses on the evolution of the town planning and the defensive system of the site. Copyright (c) 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.

The town of Classe was founded at the beginning of the fifth century ad south of Ravenna. There are a few surviving monuments, such as the basilica of St Apollinare in Classe, as well as other important sites documented by the excavations of the University of Bologna and the Superintendence for Archaeological Heritage of Emilia Romagna. These are situated particularly in the areas of the commercial port and the Basilica of St Severo. Much of the remains of the ancient town are hidden beneath modern soils. An integrated project, initiated in 2005, was conducted to learn more about the buried remains and the ancient landscape of Classe. The project used historical and cartographic sources, geology and geomorphology studies, analysis of aerial photography, geophysical and remote sensing techniques, aerial and field walking surveys, and their integration with data from archaeological excavations. In order to obtain a synthesis of all the collected data, different data sets were processed and managed using a GIS platform. The paper presents some results of this research obtained from different geomagnetic prospecting systems in three relevant areas of Classe, particularly important for understanding the ancient urban topography of the site. Copyright © 2012 John Wiley & Sons, Ltd.

One of the most important archaeological sites in Sudan is Meroe, capital city of the kingdom of Kush (800 bc to ad 400). The site is located in the Nile valley, about 200 km northeast of Khartoum. The most prominent feature among the ruins of Meroe is the Royal City: a stone-walled enclosure containing remains of palaces, governmental buildings and temples. The current study presents the results of integrated magnetic gradient and electrical resistivity tomography surveys in unexplored and partly explored areas in the central part of the site and in the southern part of the Royal City. The main enclosure wall, remains of sandstone and red-brick buildings, and a number of small archaeological structures have been traced on magnetic maps. The extent of buildings, identified by magnetic survey, has been complemented by information on the depth of structures provided by electrical resistivity tomography. The geophysical results have been partly verified through excavation. Copyright © 2012 John Wiley & Sons, Ltd.

This paper studies the applicability of the Mean Shift algorithm as support in interpreting geophysical images produced, on this occasion, from magnetic prospection data. The data obtained from a magnetic survey carried out in Gilena (Seville province, Spain) by the La Rabida Archaeophysics Group will be used for the research. Its applicability is illustrated by comparing, on the one hand, some reduction-to-pole algorithms and on the other, the (well-known) k-means algorithm. Finally, the paper shows the results obtained by applying the Mean Shift algorithm as an alternative method to ‘unsupervised clustering’ of anomalies that appear in images obtained from geophysical data, in which the a priori knowledge of the number of classes is difficult or impossible.

This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved that these approaches have yielded good results on classifying the sedimentary facies, defining the redox transitional zones and reflecting deep mineralization information. They may probably become new methods on searching for sandstone-type uranium deposits.

This short report summarizes two seasons of magnetic surveying at the Roman town of Venta Ice-norum at Caistor St Edmund, Norfolk. Survey strategies have been developd utilizing caesium vapour magnetometers mounted on a wheeled platform with a global positioning system to map former areas of settlement and their immediate hinterlands. There sulting survey system has enabled therapid collection of high-resolution magnetic data over an area of 30 ha, providing a detailed magnetic map of the former town. Details of the system configuration and survey strategy are described and data from the survey presented.

The study area is located in the Sinai Peninsula, which is considered one of the most promising regions for oil resources. Three different tectonic forces affect the area in the triple junction structures associated with the opening of the Gulf of Suez and the strike slip movement along the Gulf of Aqaba. The main goal of this work is to model the structure of the basement rocks in the study area using magnetic methods. To achieve this, a high-resolution land magnetic survey was acquired and the results were combined with existing seismic reflection data. The magnetic interpretation was carried out using the analytical signal, horizontal gradient, Euler and Werner deconvolution and 3D magnetic modelling methods. We concluded that most of the deduced structures are trending in N-S, N35°-N45° west and E-W directions. The Aqaba trend (N15°-N25° east) is barely noticeable. The depth to the basement rocks ranges from 1 km to more than 2 km below sea level and these results are in agreement with the available well log data. In addition, interpretation of seismic reflection sections was carried out and compared with overlapping magnetic profiles interpreted using Euler deconvolution. They show that the sedimentary section was affected by the basement tectonics, with faults extending from the basement upwards through the sedimentary cover. These faults constitute good potential structural traps for oil accumulation.

Analysis of results from an electrical resistivity survey, a magnetic survey, and an aquifer test performed on the Leona River floodplain in south-central Texas indicates that ground-water discharge from the Edwards Aquifer through the Leona River floodplain may be as great as 91.7 Mm 3 /year. When combined with an estimate of 8.8 Mm 3 /year for surface flow in the Leona River, as much as 100.5 Mm 3 /year could be discharged from the Edwards Aquifer through the Leona River floodplain. A value of 11,200 acre-ft/year (13.82 Mm 3 /year) has been used as the calibration target in existing ground-water models for total discharge from Leona Springs and the Leona River. Including ground water or underflow discharge would significantly increase the calibration target in future models. This refinement would improve the conceptualization of ground-water flow in the western portion of the San Antonio segment of the Edwards Aquifer and would thereby allow for more accurate assessment and management of the ground-water resources provided by the Edwards Aquifer.

A high‐resolution magnetic survey was performed on a large cultivated field located inside a heavily built‐up town in Southern Italy. Measurements with a vertical gradiometer were even carried out relatively close (down to 35 m) to sources of strong magnetic noise. Despite these particularly unfavourable surroundings, the geophysical investigation made it possible to detect and recognize buried archaeological remains from the Neolithic age.

A non-intrusive investigation integrating complementary technologies was carried out at four vast archaeological settlements located in the northern part of Apulia (Southern Italy). An aerial photographic survey combined with a high-resolution magnetic investigation was used to detect many buried archaeological features. After processing, both crop marks and magnetic anomalies appeared very sharp and well-defined, outlining the shape and plan of the buried structures with notable accuracy. Furthermore, differential global positioning system measurements were carried out in order to geocode the magnetic grids, to orthorectify the oblique coloured photographs and to make these data sets suitable for input into a GIS; a very good spatial correlation and a more rigorous and comprehensive interpretation of the various data elements were attained. Finally, as a result of this combined and accurate multilayer analysis, an archaeological interpretation was proposed, enabling useful information to be obtained on the transformations that have occurred over time at these study sites. Copyright © 2007 John Wiley & Sons, Ltd.

Results are presented from a cart-mounted caesium magnetometer system developed by English Heritage using an array of specially modified Scintrex SM4 sensors, to investigate the application of high sensitivity magnetic survey. The caesium data are compared with equivalent datasets collected with recently developed fluxgate instruments. The underlying instrument noise level for the magnetometer systems is considered together with attempts to quantify other sources of noise that potentially limit the ability to detect weak magnetic anomalies. Comparative case studies are presented from a number of English sites which demonstrate the equivalence of results that may be obtained, at similar sample densities, between caesium and fluxgate systems over well magnetized causative features. However, the caesium system exhibits a superior ability to detect very weak anomalies (≤ 0.1 nT) due to features buried beneath alluvium and has revealed additional archaeological information from small-scale changes in magnetization within the plough soil that could not be distinguished from equivalent fluxgate data. © Crown copyright 2007. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.

The site of Deir al-Barsha (Middle Egypt) is well known for its nomarchal rock tombs cut in the cliffs and dating to the Middle Kingdom (2040–1640 BC), but the presence of a necropolis of the same date in the sandy gravel desert plain was seldom mentioned in the past. Part of this necropolis had been investigated at the beginning of the twentieth century, but no plans or detailed accounts were ever published. The tombs were observed then to be structures lined with mud bricks with shafts going down several metres. In 2002, when archaeologists returned to this burial ground, few of the archaeological remains were still visible on the surface, the area being pitted with deep craters left over from the earlier excavations. The objective of the research, which was to gain insight into the overall organization and social stratification of the cemetery, required the use of the magnetic surveying method. A series of anomalies was registered in effect and interpreted as the images of shafts and accompanying ground structures (circuit walls). Several of these features have already been verified in excavations. The magnetic study has also led to the discovery of a previously unrecognized dirt road cutting across the necropolis from the nomarchal tombs to the Nile valley. The research has also attested later post-burial human activity: the magnetic maps have provided a record of several hundred of pits dug by grave robbers and not visible presently on the surface. Copyright © 2005 John Wiley & Sons, Ltd.

On the basis of the magnetic survey data during 1998-2001, the China Geomagnetic Reference Field Secular Variation model for 2000, CGRF-SV2000, is established. The model shows a slow and smooth variation of the magnetic field in China area. The unsigned average annual rates are 12.2nT/a, 8.2nT/a, 43.8nT/a, 11.8nT/a, 0.96'/a, 2.99'/a and 22.4nT/a for seven elements X,Y,Z,H,D,I and F, respectively. These rates are less than the global rates of IGRF by 1/3 to 1/2. The variations of different elements show an unified SV pattern in China: the north geomagnetic pole is moving to China, or China is moving toward high latitude at a rate 3'/a. In addition, the variation of declination D shows that the contrast of D between Eastern and Western China is enhanced. As a comparison and test, the 8-th generation of the International Geomagnetic Reference Field (IGRF) models is analyzed. The global SV estimated by IGRF models shows similar characteristics compared with CGRF-SV2000, although the annual rates of IGRF-SV are greater than those of CGRF-SV, and some regional (or local) anomalies are noted.

This report covers the application of magnetic survey, primarily using a magnetic susceptibility field instrument, at the historically attested site of KoBulawayo, Zimbabwe. The approximate position of the site was known before the geophysical survey took place; it was believed to comprise a Royal Enclosure, a surrounding open space possibly used as a military parade ground and the Commoner/Peripheral Settlement of Lobengula, King of the Ndebele. Occupation at the site was short lived and after only 11 years the capital of the Ndebele state was destroyed by fire in 1881. A pilot survey was undertaken in 1994 to assess the suitability of survey techniques. Consequently, a second, more extensive survey was carried out in late 1996 and early 1997 with the intention of delimiting the Royal Enclosure. Further periods of data collection took place later in 1997 and in 1998. This report describes the methods used and the interpretation of the geophysical results in the context of the understanding and management of this important historical site. Additionally, some of the results of the geophysical work have been tested by excavation and a discussion of the correlation between these data sets is also reported in this article. Copyright © 2004 John Wiley & Sons, Ltd.

Qasr Al-Zayyan or Al-Zayyan temple in Al-Kharga oasis is documented as a node in the fortress chain that was built by the Romans to secure Darb Al-Arbain; the slaver's trade caravan route between Asyuit and Sudan. The historical and archaeological background of the temple is very scarce; it has been ascribed to Amenebis and was restored during the reign of Emperor Antoninus AD 138–161. In March 2001, an integrated ground-penetrating radar (GPR) and magnetic survey to the west of the temple showed the possibility of an existing structural complex intersecting the present temple at about 45°. It was interpreted as a multigate structure or a tomb complex. In March 2002, the relative topographic elevations were measured and the surface archaeological features were marked on a map. Also a complementary integrated geophysical survey including electromagnetic, geomagnetic and GPR was conducted along northern and western extensions of, and partially covering, the formerly prospected structure in the survey of 2001. It was designed to verify the structure, to define its extent on both the northern and western sides, and to decide about a possible excavation. The results verified the formerly prospected structure of 2001; some of its particular features have been detected. The structure therefore has been mapped over the surveyed area at the northern and western parts of the 2001 structure and it might extend wider than the surveyed area. The former proposition of a multigate structure becomes stronger because of its general appearance, and the idea of a tomb complex still exists owing to the presence of some depressions thought to be graves. Copyright © 2005 John Wiley & Sons, Ltd.

This report details fieldwork on a suspected Roman fort in the grounds of Drumlanrig Castle. Geophysical survey was undertaken in the first instance using a 1.0 m separation fluxgate gradiometer system and the base plan of the fort was confirmed. Additionally a prototype wheeled square array was used to collect earth resistance values in order to investigate further the findings of the magnetic survey. The short report discusses some of the technical issues involved with the wheeled array and identifies technical improvements that have been implemented since the trial. Copyright © 2005 John Wiley & Sons, Ltd.

An archaeological geophysics survey was conducted on the early neolithic site of Movila lui Deciov, in the Province of Banat, Romania. Magnetometry and electromagnetic terrain conductivity were used for the main prospection effort, and a test of electrical resistivity imaging was conducted on a selected profile. In addition, magnetic susceptibility measurements were obtained from excavation pit samples. The magnetic survey was successful in determining the extent of the site, in delimiting zones rich in structures and artefacts, and in confirming the presence of a ditched enclosure that could be the earliest known in the region. The electromagnetic survey was limited by a lack of resolution of electrical property contrast. Detailed joint modelling of the magnetic and electrical response of the subsurface was used to confirm that electrical resistivity imaging can provide depth information to complement magnetic mapping. One of very few reported in Romania, this survey paves the way for an increased use of geophysical techniques in the cultural heritage management of this country. From a methodological viewpoint, this work further demonstrates the potential of electrical resistivity imaging in archaeology Copyright © 2004 John Wiley & Sons, Ltd.

The classical city of Butrint in southern Albania embodies over three millennia of settlement history. A Roman colony was established sometime after 31 BC, which led to the expansion of the city southwards onto a low-lying floodplain where settlement continued well into the late antique period. In this paper we describe the results of a detailed magnetometry survey undertaken to investigate Roman settlement upon the floodplain. The study included the use of multilayer perceptron neural networks to further process the magnetic data and derive estimates of feature burial depths, allowing a three-dimensional reconstruction of buried subsurface remains to be made. The neural network approach potentially offers several advantages in terms of efficiency and flexibility over more conventional data inversion techniques. The paper demonstrates how this can lead to an enhanced interpretation of magnetic survey data, which when combined with other geoarchaeological data can provide a clearer picture of settlement evolution within the context of landscape change. The value of this processing technique is also evident within the context of cultural resource management strategies, which potentially restrict more intrusive methods of investigation.

In 1993-1994, researchers at Oak Ridge National Laboratory collected high-resolution airborne geophysical data on the Oak Ridge Reservation, Oak Ridge, TN. The data were collected in part to address concerns about possible undocumented hazardous waste sites. Interpretation of the aeromagnetic data was complicated, however, by the discovery in remote areas of numerous small magnetic anomalies of natural origin. Magnetic susceptibility measurements of core showed that the underlying Copper Ridge Dolomite was non-magnetic. We attribute the magnetic anomalies to the presence of the ferromagnetic mineral maghemite (γ-Fe 2 O 3 ), which formed during pedogenesis of Fe-enriched colluvium that had infilled low-lying areas, including dolines. We discuss explanations offered in the literature for the formation of magnetic soils, and present evidence based on profile descriptions, thin sections, x-ray diffraction (XRD), and scanning electron microscopy (SEM), that in this case, maghemite formed either by anaerobic microbial Fe reduction followed by the formation of single-domain maghemite, or by abiological weathering and reduction of an Fe-bearing mineral followed by oxidation. Naturally occurring magnetic soils may produce magnetic anomalies similar to those characteristics of anthropogenic objects, such as buried waste drums, and complicate interpretation of airborne geophysical surveys.

Magnetic survey techniques, such as fluxgate gradiometry, depend greatly on bodies of soil developing enhanced magnetic susceptibilities. Coarse mineral soils, especially those subject to a high groundwater table, often fail to develop enhanced susceptibilities and gradiometry. An example of this is Easingwold, in the Vale of York, UK. Gradiometry detected very little, however, subsequent excavation uncovered a complex of features suggesting multiphase activity and evidence for industry. This non-detection is attributed to the coarse mineral soils and the high watertable. Several laboratory reconstructions were made to investigate the influence of specific characteristics of soil and ignition episode upon susceptibility. It was found that variations in soil texture had marked impacts on the levels of susceptibility attained, as did waterlogging. Leaching had a limited effect upon soil magnetic susceptibility, but there was variation according to texture. Copyright © 2004 John Wiley & Sons, Ltd.

The detection of induced and remanent magnetization of subsurface features provides a rapid survey technique. Rejection of the unwanted geomagnetic field and its diurnal variations is accomplished by adopting a gradient magnetometer arrangement in which only the difference signal from two magnetometers, separated by a short distance, is recorded. Nuclear resonance scalar magnetometers offer high sensitivity but have higher power requirements and therefore suffer a weight penalty relative to fluxgate types. Fluxgate magnetometers are vector sensing and their sensitivity is limited, mainly by thermally induced mechanical and electronic drift. This paper describes the development of a 1-m separation, vertical component, fluxgate magnetometer that alleviates these problems. Single and multiple array gradiometer configurations are presented, together with a description of data logging software developed to enhance survey efficiency. Survey data acquired during trials and testing are presented. The ergonomics of portable instrument surveying is also discussed. Copyright © 2003 John Wiley & Sons, Ltd.

The results from a magnetic survey and archaeomagnetic investigation of a medieval brick kiln at Kungahalla in Bohuslan (south-west Sweden) are reported. Detailed magnetic total field and magnetic gradient measurements over known traces of the kiln showed marked local magnetic anomalies of up to 200 nT, revealing the rectangular shape of the kiln remains. Palaeomagnetic investigations of the remanent magnetization of 12 bricks from the kiln floor gave precise definitions of both the direction of the archaeomagnetic field [(D m , I m ) = (66.7°, 8.8°), k = 655, α 95 = 1.7°] and the palaeointensity [B m = 69.0 ± 3.6 μT]. An archaeomagnetic date is obtained by comparing the direction of the archaeomagnetic fteld found in the kiln with a geocentral dipole-transformation of the British master-curve for secular variation. Of two possible archaeomagnetic dates (AD 1280 ± 50 or AD 1480 ± 50), the AD 1280 ± 50 age is in good accordance with the C-14 ages and archaeological dates as well as with direct historical evidence, whereas a c. 100 years younger TL date appears to be too young.