The use of ground-penetrating radar in archaeology

New techniques of ground-penetrating radar (GPR) acquisition and computer processing were tested at archaeological sites in the American Southwest and found to be highly effective in producing images of buried archaeological features. These new methods, especially amplitude slice-maps, were combined with more standard data processing and interpretation techniques and tested at sites with little or no surface expression. In southern Arizona, numerous pit structures buried in terrace alluvium were discovered and mapped. In the Four Corners region, a Chaco period great kiva and other pit structures and features were mapped by GPR and later confirmed through excavation. At some sites, GPR surveys did not successfully identify buried archaeological features. These failed surveys highlight both geological and methodological problems including soil conditions, surface disturbance, and equipment calibration that may be avoided or ameliorated in future GPR surveys.

هر روش ژئوفیزیکی مزایا و معایب ویژه خود را دارد. تلفیق نتایج حاصل از برداشت به روش‌های مختلف ژئوفیزیکی سبب پوشش نقطه ضعف هر روش به وسیله روش‌های دیگر می‌شود. به همین دلیل بررسی‌های مختلف اکتشافی، مهندسی، زیست محیطی و غیره با استفاده از چندین روش مختلف ژئوفیزیکی، معمولا نتایج معتبرتری را در اختیار قرار می‌دهند. در این پژوهش نیز سعی شده است تا با تلفیق نتایج برداشت به روش‌های توموگرافی مقاومت ویژه الکتریکی (ERT)و رادار نفوذی به زمین (GPR) به بررسی نقاط قوت و ضعف هر یک از این دو روش‌ پرداخته و در پایان، در نتیجه تلفیق نتایج، تفسیر دقیق‌تر و با اطمینان بالاتری ارائه شود. روش ERT یکی از روش‌های برداشت بهینه از زیرمجموعه‌های روش مقاومت ویژه است که در مناطق با زمین‌شناسی پیچیده نتایج قابل اتکایی را در اختیار قرار می‌دهد. روش GPR نیز از روش‌های غیر مخرب ژئوفیزیکی با قدرت تفکیک بالا است که در آن با ارسال امواج الکترومغناطیس بسامد بالا به زمین و ثبت امواج بازتابی از فصل مشترک لایه‌های زیر سطحی، به بررسی‌ زیر سطح زمین در ژرفای کم پرداخته می‌شود. در این پژوهش، قنات به عنوان هدفی مناسب برای شناسایی با این دو روش انتخاب و سپس، برداشت‌های ERT و GPR بر روی منطقه دربرگیرنده هدف مزبور انجام شد. نتایج حاصل از پردازش، مدل‌سازی و تفسیر داده‌های برداشت شده نشان داد که از نقطه نظر مقایسه دو روش یادشده، روش GPR قدرت تفکیک بالاتری دارد ولی روش ERT دارای ژرفای نفوذ بیشتری است. این دو روش در نشان دادن پدیده‌هایی مانند وجود حفرات، تغییرات در ابعاد ذرات و نیز نفوذ رطوبت توافق و همخوانی خوبی دارند. همچنین با تلفیق نتایج حاصل از این دو روش با یکدیگر مشخص شد که دقت و اطمینان تفسیر به طور قابل ملاحظه‌ای افزایش ‌می‌یابد.

The Ground Penetrating Radar (GPR) method potentially offers many possibilities for fast and reliable lithostratigraphic sediment models to be developed. From a cognitive point of view, this represents a major simplification and shortening of procedures with which information about sediments can be obtained. And from the point of view of the economy of operations, there can be a significant reduction in costs and time of research in shallow geology and the stratigraphy of areas where unconsolidated clastic sediments are of superficial occurrence. Also noteworthy is the possibility for the results of GPR surveys to be deployed in support of geological mapping, as well as in the shallow exploration of resources and hydrogeological studies.The most major advantage of the GPR method related to the possibility of the structure of forms being observed in full shape. In the absence of large outcrops, geophysical prospection of geomorphological forms is helpful, insofar as we are able to translate the results of geophysical surveys into the actual lithostratigraphic system of sediments building a specific form.Against that background, the research presented in this article forms part of the work to develop radar stratigraphy, as an important support for direct geological research (Huggenberger et al., 1994; Van Overmeeren, 1998; Beres et al., 1999, Overgaard and Jakobsen, 2001; Jakobsen and Overgaard, 2002; Neal, 2004; Lejzerowicz et al., 2014; Żuk and Sambrook Smith, 2015; Lejzerowicz et al., 2018). It also points to the research potential of the GPR method in determining the genesis of form. The discussion on the way kames form has been going on in the literature for years (Niewiarowski, 1959; 1961; Karczewski, 1971; Klajnert, 1978; Jaksa, 2003; Terpiłowski, 2008). The studies presented here do not suffice to allow the matter to be determined comprehensively, even though they do provide for verification of the opinions of previous researchers.The area forming the subject of this article is defined by Niewiarowski (1959) as the dead ice zone because of the characteristic set of forms (dead ice moraines, kames and eskers). Like modern researchers (Terpiłowski, 2008), Niewiarowski points to the importance of sub-Quaternary surface elevations in the formation of cracks in the ice sheet, with this leading on to the formation of kame hills above such elevations. This would also seem to have been one of the reasons for the formation in the mass of ice of lakes whose filling with sediment and melting ice walls took the form of kames.The great advantage of the GPR method lies in its ability to recognise macrostructural sediment patterns in glacilimic forms. This diagnosis allows for the high-probability assessment of the genesis of form, especially in the context of its position being determined in the marginal zone of the ice sheet. Also looking extremely promising is the capacity for the thickness of fine clastic sediments lying on till to be determined using GPR. It allows for the determination of the way in which a given form is rooted.Described as they are in brief only, test results for selected sites serve to confirm the great usefulness of the GPR method in the recognition of shallow lithostratigraphy of clastic sediments. Nevertheless, this should not be the only method used to recognise the geological structure of forms and sediments. Significant interpretation ambiguities mean that the GPR method should act in support of direct lithostratigraphic research, not merely serving as an alternative to it. GPR surveys offer a depiction particularly close to the real one – of sediment present in homogeneous sediments in relation to electrical parameters. Sediments ideal for GPR surveys would for example be fine dry sands or silts – and it is precisely these sediments that built most of the investigated kame forms.

Twelve kilometers of ground penetrating radar (GPR) data have been collected over the Brookswood aquifer in southwestern British Columbia. The data have been analyzed to assess how GPR can be used to characterize the distribution and connectivity of hydraulic units. We have used GPR to locate the aquifer/aquitard boundary at several locations in the study area. The electrical contrast between these two materials makes the aquifer/aquitard boundary an excellent target for GPR surveys. GPR was also used to reconstruct the paleo-environment of one area of the Brookswood aquifer. This was accomplished by using a modification of the concept of architectural element analysis. Radar elements were identified in the survey and were assigned sedimentary parameters using data from trenching and drilling in the area. These elements were used to develop an interpretation of the paleo-environment that provides information about the spatial distribution of hydraulic units. INTRODUCTION Hydrogeologists require quantitative data to produce a realistic model of the spatial variabilities in hydraulic properties of an aquifer. Such data can be difficult and expensive to obtain. A possible solution is to develop geophysical techniques as a means of aquifer characterization. Ground penetrating radar (GPR), a shallow geophysical technique, is well suited for this purpose as it can be used to image to a depth of up to 30m in sand and gravel environments. However, the image produced by a GPR survey does not supply hydrogeologic parameters directly. The focus of this paper is to investigate how GPR can be used for aquifer characterization. At an aquifer scale of lo’s to 100’s of meters, the most fundamental aspect of aquifer characterization is the determination of the aquifer’s hydraulic connectivity through mapping of aquifer/aquitard interfaces. GPR can be used for this purpose due to the large contrast in electrical conductivity between the sand and gravel material of an aquifer, and the clay rich material of an aquitard. The electrical conductivity of a material affects the penetration depth of radar waves, such that radar waves penetrate well through resistive material, but poorly through conductive material. Aquifers, composed of sands and gravels, are resistive, while aquitards, composed of clay rich materials, are electrically conductive. Therefore a radar survey will show good penetration in aquifer materials and very poor penetration in aquitards. By exploiting this difference in radar response, the aquifer boundaries can be mapped. At a smaller scale of centimeters to meters, the determination of the internal structure of an aquifer is also important for aquifer characterization. For example, anisotropy within the aquifer can cause significant differences in hydraulic properties and so must be identified where present. In addition, identification of sedimentary features aids in the determination of the paleo-environment that can provide important insight into the probable arcal extent and orientation of geological units. GPR can be used to image these features because of changes in their electrical properties. GPR and Sedimentology GPR has received considerable attention as a means of imaging sedimentary stratigraphy (Jo1 and Smith, 1992; Smith and Jol, 1992; Pratt and Miall, 1993; Greenhouse et al, 1987; Rea et al, 1991; Huggenberger et al, 1994). The key question that needs addressing is exactly which sedimentary aspects of the subsurface are imaged with GPR. A GPR survey, conducted by transmitting radar waves into the subsurface and recording the reflected energy, will image changes in the subsurface dielectric constant and conductivity. If these electrical properties correspond to changes in sedimentary parameters, then a GPR survey can be said to image sedimentary features. The dielectric constant and conductivity of earth materials are dependent upon composition and geometry of the solid and liquid components. Sedimentological classification is based upon five fundamental properties from which all others can be derived: grain composition, size, shapes, orientation and packing (Blatt et al, 1980). These five properties clearly are related to the composition and geometry of the solid component of a system. It is therefore reasonable to assume that a change in sedimentological properties at some boundary will cause a change in electrical properties. If the resulting change in electrical properties is large enough, then the sedimentary boundary will be imaged in a radar survey. The complicating issue is the liquid, usually water, component which does not play a role in sedimentary

The purpose of this work was to compare the mapping of shallow subsurface archaeological structures through Seismic Refraction Tomography (SRT), Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) methods. For achieving the goals of the project, a specific section of the archaeological site in Delphi has been surveyed through the employment of the above techniques. For the SRT survey, twenty four P-wave geophones were installed randomly in a 50 by 40 m area. Totally seventy three (73) shots were made by striking a metal plate with a sledgehammer to collect about 1752 travel-times. The pole-dipole array was employed to capture the ERT data along twenty densely spaced parallel profiles. The GPR data were collected along parallel sections with a resolution of 50 cm between the lines. The SRT and ERT field data were processed with modern tomographic inversion algorithms for the reconstruction of the 3-D velocity and resistivity models describing the buried archaeological remains and the subsurface matrix up to the depth of 5 meters below the ground surface. GPR signals were enhanced with specific filters signifying the shallow structures up to 2 meters below the ground surface. The integrated processing results indicate the existence of walls buried in a relatively uniform background soil. The outcome of this approach signifies that SRT, ERT and GPR methods can be used as a validation tool in any archaeological investigation by providing accurate tomographic subsurface models and contribute in cultural resources management.

The main goal of the study was to compare the potential of conventional and geophysical methods (ground-penetrating radar; GPR) to reconstruct the migration phases of a meandering lowland riverbed: the Obra River in western Poland. The purpose was to verify that the migration phases can be distinguished using the GPR measurement providing near-continuous imaging of alluvial structures and to discuss differences between the spatial extent of the migration phases distinguished using geologic data and GPR surveys. Historical maps from the eighteenth and the nineteenth century were analyzed to study transformations of the Obra River bed pattern. One hundred twenty tube sample borings were undertaken along five profiles to recognize the floodplain lithology. Granulation coefficients were determined using the method of moments to distinguish lithofacies of the alluvial deposits. The GPR measurement was performed using a georadar MALA ProEx equipped with shielded 100 and 250 MHz antennae. The GPR images were compared to geologic profiles to determine the depth scale and accuracy of the measurements. The depth scale of the GPR images was determined on the basis of the correlation of the radar reflections with the geologic profiles. Ten organic sediment samples were collected to determine the age of the migration phases. Point bars with layering of sand deposits, organic sediment fills, erosion surfaces, and gravel beds were distinguished using the 250 MHz antenna. However, some of sedimentary structures (e.g., inserts of fine sands in the organic deposits) were beyond the detection range of the antennae. The glacial/alluvial sediment interface was detected using the 100 MHz antenna which enabled the determination of the thickness of the alluvial fill. Traces of a period of early development of the Obra valley and three migration phases of the Obra River bed were distinguished. The research indicated that the Obra was a meandering river at least 7,000 years before present and that during the last 3,000 years, channel islands were formed within the studied section of the valley. The GPR method allowed for the analysis of the spatial variability of alluvial deposits and helped to describe how meander bends were formed. The presented GPR images illustrate the spatial extent of the migration phases in a more detailed way than using only sedimentary information. However, geologic data are necessary for interpretation of the GPR images. It was shown that the GPR method gives useful results in spite of rough land surface and dense vegetation.

Important research and technical issues are related to the prospection in urban area to locate subsurface cavities and/or archaeological remains and to produce hazard mapping. In many cases, cavities, voids and collapses represent disruptions to the geometry of an originally near-horizontal layered system. Geophysical techniques can be employed to identify the feature geometries by contrasts in the physical properties, but can be strongly conditioned by cultural features that interfere with instrument measurements (utilities, structures, surficial debris).The most promising non-destructive geophysical prospection method for use in urban area is GPR. GPR measurements are less affected by the presence of metallic structures compared to magnetometer prospection and they result in the largest amount of data of all commonly employed near-surface geophysical methods, providing detailed three-dimensional information about the subsurface [1], [4]. In thist paper the surveys made with GPR to investigate different sites in the area of S. Giovanni in Laterano and Santa Croce in Gerusalemme in Rome, as part of the ERC funded Rome Transformed project (2019-2024) are presented and discussed. The aim of the GPR survey is to identify Roman and high-medieval age remains which could enhance understanding of the ancient topography and the urban evolution of the study area.For the surveys a GPR SIR3000 (GSSI), equipped with a 400 MHz (GSSI) bistatic antenna with constant offset, a 70 MHz (Subecho Radar) monostatic antenna and a SIR4000 system equipped with dual frequency antenna with 300/800 MHz were employed.All the GPR profiles were processed with GPR-SLICE v7.0 Ground Penetrating Radar Imaging Software. The basic radargram signal processing steps included: (i) post processing pulse regaining; (ii) DC drift removal; (iii) data resampling; (iv) band pass filtering; (v) background filter and (vi) migration. With the aim of obtaining a planimetric vision of all possible anomalous bodies, the time-slice representation technique was applied using all processed profiles up to a depth of about 2.5 m, [2], [3]. Ground Penetrating Radar (GPR) survey at the selected areas has produced significant and fruitful results that will be discussed during the presentation. References1 - I. Trinks, P. Karlsson, A. Biwall and A. Hinterlaitner, Mapping the urban subsoil using ground penetrating radar – challenges and potentials for archaeological prospection, ArchaeoScience, revue d’archeometrié, 2009, suppl. 33,  pp. 237-240.2 - D. Goodman and S. Piro, GPR Remote sensing in Archaeology, 2013, Springer (Ed), ISBN 978-3-642-31856-6, ISBN 978-3-642-31857-3 (eBook), DOI 10.1007/978-3-642-31857-3. Springer, Berlin, (Germany).3 - S. Piro S. and D. Goodman, Integrated GPR data processing for archaeological surveys in urban area. The case of Forum (Roma, Italy), 2008, 12th International Conference on Ground Penetrating Radar, June 16-19, 2008, Birmingham, UK. Proceedings Extanded Abstract Volume.4 - Piro S., Zamuner D., 2016. Investigating the urban archaeological sites using Ground Penetrating Radar. The cases of Palatino Hill and St John Lateran Basilica (Roma, Italy). Acta IMEKO, Vol. 5, issue 2, pp 80-85. ISSN: 2221-870X. DOI: 10.21014/acta imeko/v5i2.234 . 

This paper describes the ground penetrating radar (GPR) survey performed on the archaeological site of Ciavieja, El Ejido (Spain). It is part of historical studies performed in Ciavieja in order to add information to previous studies and also to analyze the extent and importance of the remains buried in this site. The objective of the GPR survey was to locate the most promising areas within the archaeological site to help the architects and archaeologists with an optimal design for the park. The time slices built with the radar data show several locations with linear and square anomalies with sizes compatible with the ones of Roman walls or roman house rooms.

The Ground Penetrating Radar survey can increase the amount and quality of the information when applied to archaeological prospection. In comparison to other geophysical methods, the Ground Penetrating Radar method's effectiveness rests in its applicability to a wide variety of site variables as well as the complementary nature of the data. One more benefit of the use of Ground Penetrating Radar for this investigation is that an archaeological location is usually ‎shallow, which facilitates the Ground Penetrating Radar with an enhancement in the resolution achieved. An area with dimensions of ×19 m dimensions was taken in cooperation with the Heritage and Antiquities Authority. This area was regularly divided into a group of lines in North-South and West-East, representing the radar device’s path. The Tall Abo_Al-Za’ar district was surveyed using Seventy-two parallel and two antennas, 450 and 750 MHz, used respectively, for each survey. The results of this research showed the presence of several zones, the first represented by the upper layer, which ranges from 0.5-1 m, which is the burial area, as is evident in the Ground Penetrating Radar Image, interspersed with broken parts of the materials from which the walls of the area made. The second zone is located directly below the burial layer, and it is clear that there are archaeological walls made of clay at different depths. The last zone, located below the depth between 4-5m, represents the water-saturated area, which decreased the specific resistance, which caused loud noises and the inability to know what was in this range. The 2D view of the Tall Abo_Al-Za’ar district shows that the archaeological anomalies are distributed randomly and with different widths, and it was not possible to know the thickness of the walls in the area due to the high humidity.

Identification of liquefaction and deformation features using ground penetrating radar in the New Madrid seismic zone, USA

Ground penetrating radar (GPR) is a very useful geophysical method for use in hydrogeologic and near-surface mapping studies. It can be used to study contaminants in groundwater, subsurface faulting, and underground cavities (natural or man-made), all of which pose potentially dangerous geological hazards. The GPR technique is similar in principle to seismic reflection and sonar techniques. The propagation of the radar signal depends on the frequency-dependent electrical properties of the ground.Electrical conductivity of the soil or rock materials along the propagation paths introduces significant absorptive losses which limit the depth of penetration into the earth formations and is primarily dependent upon the moisture content and mineralization present.Reflected signals are amplified, and transformed to the audio-frequency range, recorded, processed, and displayed. From the recorded display, subsurface features such as soil/ soil, soil/rock, and unsaturated/saturated interfaces can be identified. In addition, the presence of floating hydrocarbons on the water table, the geometry of contaminant plumes, and the location of buried cables, pipes, drums, and tanks can be detected. The GPR data are presented as a two-dimensional depth profile along a scanned traverse line in which the vertical axis is two-way travel time measured in nanoseconds. The location of hydrocarbon contamination in the ground using the GPR method is based mainly on information taken from reflected signals. In the cases investigated in Romania contaminated sites (Navodari area), such signals were very rarely recorded. A long time after spillage, contamination takes the form of plumes with different size and distribution, which depends on the geological and hydraulic properties of the ground. The survey discussed in this paper was carried out using the GPR system-Noggin with two antennas (250 and 500mHz) Data collected were processed using software(EKKO_Project™ GPR Data Analysis) to produce 2D radargram in time scale. The presence of contaminant plumes as well as the water table are observed in the GPR sections at depths approximately of 0.5 to 1.5 m. In the GPR section, the oil contaminated layer exhibits discontinuous, subparallel, and chaotic high amplitude reflection patterns. Promising results were also obtained in the GPR survey where three obvious reflection patterns representing the top sand-silt layer, oil-contaminated zone and, the underlying thick soft clay were detected in all 2D radargrams of the GPR traverse lines.

Paper is dedicated to geophysical mapping of polygonal wedge ice. Magnetometric and ground penetrating radar surveys were implemented on a small area of Yedoma ice complex on Kurungnakh island in Lena river delta. Such deposits are widely spread on a huge areas of Siberia and Alaska. The study was conducted near the thermoerosional gully, which propagates along the most thick ice wedges. Polygonal pattern is observable on high-resolution aerial imagery and digital elevation model - this data was used during the interpreting of obtained results. Study area (40×50 m) was covered with highresolution magnetic survey at the elevation of 2 m with 2×2 m step and with ground penetrating radar survey along profiles with 1 m distance between the profiles. Map of total magnetic field anomalies allow to determine the ice wedges of Yedoma ice complex distinctly. Difference between maximum positive (polygons centers) and negative (ice wedges) anomalies reaches 6 nT (error of the survey is 0,3 nT). Beyond that smaller ice wedges which penetrate the ice wedges of Yedoma complex are also observable in magnetic field. Basing on ground penetrating radar data an amplitude slice of at 3,5 m depth was built. Yedoma ice wedges are observable at depth of 3–4 m. Ground penetrating radar data is quite noisy due to surface inhomogeneity (puddles, knolls, etc.). Results of the surveys were compared in the light of practical application of the methods for above mentioned goal. Magnetometric method appears as more efficient than ground penetrating radar survey: it does not require a contact with the surface and more rapid, it is more sensitive as the case stands. Ground penetrating radar method may have advantages in the case of natural (magnetic storm, high-magnetized overlaying deposits) and anthropogenic (metal constructions — pipelines, ETL) noise.

Archaeological evidence has demonstrated that the Bujang Valley is Malaysia's richest archaeological site and served as the primary coastal centre. A study in the Bujang Valley found monuments related to trading activities and others that functioned as a temple related to the Hindu-Buddhist period. The main purpose of this study was to resolve issues and problems arising from previous studies related to the Bujang Valley civilisation, particularly in terms of iron studies. Geophysics plays a vital role in assisting archaeologists to obtain excellent preliminary results before they proceed with excavation and digging works. Therefore, the 2-D resistivity and ground-penetrating radar (GPR) methods were conducted to locate and map the potential iron smelting site at Site B2 (SB2). Three main characteristics that can be observed on the surface are a mound area, exposed clay bricks and surface finds. Two-D resistivity showed the resistivity values of a possible buried structure, with values > 800 Ωm. Radargram profiles showed the highest amplitude, indicating the reflections uncovered in the location in certain survey lines. This paper presents the first summary of research on the metallurgical sites in the Bujang Valley, the most important site in Malaysia. Geophysical methods, which rely on a physical contrast between buried archaeological features and the properties of the surrounding subsoil, can assist archaeological investigations.

Cape Henlopen, Delaware is a coastal spit complex located at the confluence of Delaware Bay and the Atlantic Ocean. This region was occupied by prehistoric peoples throughout the evolution of ancestral Cape Henlopen. A ground-penetrating radar (GPR) survey was conducted at one of the prehistoric archaeological sites (7S-D-30B) located within the Cape Henlopen Archaeological District. The site was in a remote location in the center of a tide dominated back-barrier marsh. Ground-penetrating radar waves penetrated to depths of 7 m, and four major sets of reflections were observed. Three sets were interpreted to be GPR images of geomorphic units associated with the spit complex, and the fourth was identified as the GPR image of a shell midden deposit. The GPR survey was used to determine the approximate dimensions of the shell midden, including its depth below ground surface (up to 2.1 m) and horzontal extent (∼250 m2), and to establish the paleoenvironmental setting and antecedent topography of the site prior to occupation. The GPR data suggests that the shell midden was initially deposited upon an aeolian dune surface and the antecedent topography at the site included an up to 1 m deep trough located 5 m to the north of, and trending parallel to, the axis of a present-day topographic high. This survey illustrates that GPR is a useful, noninvasive, tool that may be implemented at archaeological sites in coastal areas. It provides constraints on the environmental setting and topography of the terrain which prehistoric peoples inhabited, and it can be used in planning excavations at sites in coastal geomorphic settings. © 2000 John Wiley & Sons, Inc.

Ground penetrating radar and shear-wave reflection methods were used to characterize the shallow subsurface. Both methods were compared at a site in south western Sweden. The site, which consists of a [Formula: see text] long profile, was chosen based on existing site information from previous studies. The shallow subsurface consists mainly of sediments of sand and clay. Ground penetrating radar methods, using common-offset and multi-offset techniques, in combination with common midpoint processing, were compared regarding resolution and depth penetration. It is shown that the latter strategy provides more distinct reflections and allows a deeper range of interpretable reflectors. The shear-wave reflection method images overlapping and deeper parts of the section which are below the depth range resolved by the radar waves. The study shows that by combining information from ground penetrating radar and shear-wave reflection surveys, a more complete analysis of subsurface geology can be conducted. Also in conductive environments, the shear-wave reflection method offers a possible alternative to ground-penetrating radar.