Use of ground penetrating radar to map subsurface archaeological features in an urban area

The ground penetrating radar (GPR) technique was used to investigate the subsurface in an urban area located in Mesagne (Italy) to obtain a map of the archaeological features in the ground. The GPR survey was undertaken at selected locations placed near (about 50 m) to a necropolis dating from the Messapian to the Roman imperial age, using a GSSI Sir System 2 incorporating 200 and 500 MHz centre frequency antennae. The selected areas (A and B) were surveyed along parallel 1 m spaced profiles using a 200 MHz antenna in area A and along parallel 0.5 m spaced profiles using a 500 MHz antenna in area B. For the selected areas the processed data were visualised in 3D space not only by means of the standard time slice technique, but also by means of a recently proposed approach, namely by iso-amplitude surfaces of the complex trace amplitude. The immediacy in revealing the spatial positioning of highly reflecting bodies, such as the anomaly interpreted as an old hypogeum room in area A, makes 3D visualisation techniques very attractive in archaeological applications of GPR. Their sensitivity to the signal/noise ratio is, on the other hand, highlighted by the quite poor performance in area B, where the only reliable result provided by all the techniques was the ancient living surface reflection, whereas none of them could effectively enhance the visibility of weak hyperbola reflections noted on 2D sections and probably related to the walls located on the ancient living surface. The performance of the various techniques in these two different situations allowed insights into their main advantages and drawbacks to be gained.     

Integrating pedological and geophysical methods to enhance the informative value of an archaeological prospection – The example of a Roman villa rustica near Regensburg,Germany

Geophysical prospection techniques are widely used to visualize the buried past. Various methods such as magnetometry, electric resistance mapping and electric resistivity tomography and ground penetrating radar yield different results. The use of all three techniques in combination with aerial photography interpretation and pedological mapping is highly effective, but it requires a multi-layer approach. This paper presents such a multi-layer approach carried out at a site with buried remnants of a Roman villa rustica in southern Germany. The integration of the various results into a geographical information system leads to a geocodation of all outcomes and a final archaeological interpretation. Several buildings in different states of preservation, different kinds of ground floors both with and without hypocausts, perimeter walls and kilns could all be detected. The soil mapping results helped in the geophysical interpretation by outsourcing soil erosion and accumulation areas. It is shown that none of the employed methods could have supplied all the compiled information on their own, and the strengths and weaknesses of each method is discussed in order to point out the implications for archaeologists.     

Understanding the built environment at the Seneca Iroquois White Springs Site using large-scale,multi-instrument archaeogeophysical surveys

A landscape-scale conception of the circa 1688–1715 CE Seneca occupation at the White Springs Site (NYSM 1952; RMSC Plp-018), located in Geneva, NY, is important for understanding their built environment during a period of residential upheaval. This paper reports on approximately five hectares of high-resolution, multi-instrument archaeogeophysical surveys. These surveys allowed engagement with layered, temporal contexts and the gathering of otherwise inaccessible information. In combination with excavation, surface survey, and historic research, archaeogeophysical techniques provided expanded access to the site, a settlement size estimate of 1.42–2.75 ha, and tentative evidence for a palisade at the White Springs Site. The interplay between archaeogeophysics and other techniques was critical to this undertaking.     

地质雷达文物勘察技术应用研究——以元上都为例

本次研究主要利用地质雷达对元上都遗址进行了勘察研究。通过对采集的数据进行处理分析并经过反复的研究分析出了外城东西大道的道路情况与明德门基础的详细情况和城门外护城河的相关信息。同时也提出了地质雷达特征图像识别的规律,为以后地质雷达在遗址探测中提供了很好的利用经验。并且进一步提出了物理探测和岩土类型遗址保护工作实际情况相结合的文物勘察方法——无损文物勘察。     

Ground Penetrating Radar in the Northern Great Lakes: A Trial Survey of a Contact Period Occupation in Marquette County,Michigan

ABSTRACT

Timing, inclement weather, and limited budgets can obstruct archaeological survey efforts. Here, we ameliorate some of these with use of ground penetrating radar (GPR) at the Goose Lake Outlet #3 (GLO#3) site (20MQ140). GPR surveys to guide survey and excavation efforts in these well-drained sandy soils are limited. GPR imagery exhibited false positives; however, shovel probes, subsequent site excavation, and artifact analysis led to numerous discoveries at this protohistoric site—including glass trade beads dating to the 1630s. These discoveries solidify evidence for some of the earliest European-made trade items in the region and provide further confirmation for placement of an Indian trail and ancient travel corridor between Lake Superior and Lake Michigan. Two ¹⁴C samples obtained from moose-bone in features with trade goods fall within the expected occupation range of 1633–1668 and 1615–1647. Several anomolies, possible hearth clusters were seen on the GPR imagery; however, many features remained invisible.     

Integrated seismic tomography and ground-penetrating radar (GPR) for the high-resolution study of burial mounds (tumuli)

The study primarily aims at providing adequate imaging resolution of large and prominent targets of archaeological interest, such as pyramids and tumuli, at all depth levels. We implemented an integrated seismic tomography and georadar (STG) technique to perform high-resolution imaging and characterization of tumuli (burial mounds). We tested the proposed technique on a preserved late Bronze Age burial mound in northern Italy, for which STG succeeded in performing an accurate 3-D reconstruction of the structure and stratigraphy as proved by later archaeological excavations. We completed two transmission seismic tomography measurements, at present ground level and at 1.5 m elevation, with a 24-channel seismograph and 15° angular separation between geophones. The ground-penetrating radar (GPR) dataset encompasses 12 250 MHz radial profiles and 12 common mid point gathers for velocity analysis. Shallow layers of the mound are successfully imaged by GPR, whilst the structure of the deep central part of the tomb is reconstructed from seismic traveltime inversion. In particular, GPR images lenses and layers of sediments forming the external part of the tumulus, evidences of a looting attempt, peripheral structures associated with later exploitation of the mound (furnaces) and, in the external sector of the tumulus, the top of the deep layer of silty sediments covering the funeral chamber. Tomographic results reveal seismic velocity anomalies of potential archaeological interest at ground level, which were successively validated by archaeological excavations. The integration of GPR and tomographic datasets is an effective strategy to overcome the imaging and interpretation problems related to the structure of such peculiar funeral monuments. STG can be applied to a virtually unlimited dimensional range and requires a limited data acquisition, processing and inversion effort. The results of the study allowed the identification of the funeral chamber and a detailed imaging of layering and structural details.     

Medieval phases of settlement at Benabbio castle,Apennine mountains,Italy: evidence from Ground Penetrating Radar survey

The lack of written sources for many of the medieval castles in the northern Apennines (Italy) makes it difficult to completely establish the most ancient historical phases of these settlements. The church of San Michele belongs to an abandoned fortified settlement of the Castle of Benabbio, in the mountains surrounding Lucca. Thanks to an epigraph still visible on the façade, the church foundation is dated back to AD 1218. However, several archaeological findings at the settlement seem to suggest stages of encastlement that are older than the church foundation.     

Integrating Multi‐Sensor Remote Sensing Data for Land Use/Cover Mapping in a Tropical Mountainous Area in Northern Thailand

Accurate mapping of land use/cover conditions provides essential information for managing natural resources and is critical for further examination of land use/cover change and its subsequent impacts on the environment. Remote sensing offers a means of acquiring land use/cover data in a timely manner, with optical remote sensing images commonly being used in land use/cover related studies. The persistent cloud cover during the rainy season in Southeast Asia, however, presents a challenge for using optical images in land use/cover mapping. Integrating multi‐sensor images of different spectral domains is thus desirable because more information can be extracted to improve the mapping accuracy. The purpose of this study is to assess the potential of using multi‐sensor data sets for land use/cover mapping in a tropical mountainous area in northern Thailand. Optical data from Landsat Thematic Mapper, radar images from Advanced Land Observing Satellite/Phased Array type L‐band Synthetic Aperture Radar (PALSAR), and topographical data were used, providing complementary information on land use/cover. Classification and accuracy assessment were conducted for 12 different combinations of the data sets. The results suggested that short crop mapping using multi‐temporal Phased Array type L‐band Synthetic Aperture Radar images offered insights into the distributions of crop and paddy fields. Because of the mountainous environment of the study area, combining topographic data of elevation and slope into the classification greatly reduced the confusion between different land use/cover types. Improvement of classification accuracy was evident especially in separating evergreen and deciduous forests from other vegetation types and discriminating urban village and the fallow field classes.     

Integrated geophysical surveys for the subsurface mapping of buried structures under and surrounding of the Agios Voukolos Church in İzmir,Turkey

This work presents the results of the integrated usage of geophysics in the Agios Voukolos Church, one of the unique Orthodox constructions in ?zmir. The surveys had two main objectives: to define subsurface characteristics inside and around the church and search for possible structural damage such as cracks and fissures, that may exist in the subfloor of the church. Magnetic gradiometry, ground penetrating radar and electrical resistivity tomography were used in the investigations; this study is the first indoor application of magnetic gradiometry. The studies revealed that several suspicious relics and crypts might have existed under the floor of the church. In addition, investigations of the courtyard area indicated potential buried structures under the settling area of the church. This study demonstrates the importance of the integrated usage of non-destructive geophysical techniques in searching for possible hidden subsurface structures in standing historical buildings. In addition, magnetic gradiometry might be useful in indoor studies, assuming that there are no important magnetic sources near the site.     

Imaging skeletal remains with ground-penetrating radar: comparative results over two graves from Viking Age and Medieval churchyards on the Stóra-Seyla farm,northern Iceland

Detailed ground-penetrating radar surveys were conducted at separate Viking Age and Medieval churchyards on the Stóra-Seyla farm in Skagafjörður, northern Iceland. Surveying over a previously unknown site (ca. AD 1000) that is located just a few meters above the Skagafjörður valley bottom delineated the remnants of a buried circular turf wall that encloses a church structure and several graves. The radar profiles over the graves contain strong hyperbolic reflections that emanated from the skeletal remains. Over one of the graves, an air-filled void within the chest cavity had been detected as noted by reflections with normal polarity which indicated a boundary towards increasing microwave velocity. During excavation, the soil surrounding an intact rib cage collapsed thus confirming the presence of the void. In general, the skeletal remains were very well preserved and yielded strong reflections which permitted the orientation of the body to be determined. Conversely, the radar profiles over a grave from a more recent churchyard (ca. AD 1200) show ground disturbance but lack hyperbolic reflections. Upon excavation, only teeth were recovered. The poor preservation of the skeletal remains is attributed to increase contact with infiltrating groundwater from an overlying gravel layer. Interpretations were aided by time-slice overlay imaging, forward modeling and analysis of the reflection coefficient.