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1. The main concepts of our GPR

2. Experience of georadar "Grot" application for mapping of a cultural layer on archeological excavation

3. Archeological Investigation below the Sea Bottom by Underwater Ground Penetrating Radar



By the order of Moscow Region archaeological expedition of the Institute of Archaeology, Russian Academy of Science (RAS), GPR inspection of an ancient settlement excavation (D'yakovsky period, early iron age, 4-3 centuries BC) was carried out. This ancient settlement is located near village Myachikovo in Kolomna district of the Moscow Region. The inspection of the excavation was carried out by the georadar GROT (design of the device has been reported at the 6th GPR Conference in Sendai, Japan).The research problem consisted in the mapping of buried earthen fortification structures of the ancient settlement. According to the data of aerial photography, sectors of two concentric strips, distinguishable due to more saturated color of vegetation, were well visible in the territory surrounding the excavation. According to the archaeologists version, the vegetation indicated the borders of the interred fortification structures. The GPR inspection of the territory around the settlement showed, at the depths of 1.5 to 2 meters, some structures similar to a buried ditch. The "ditch" width was about 5-6 meters; radius from the settlement center was 20 meters for the internal, and 30 meters for the external ditch. Georadar cross sections superimposed on the excavation map allowed us to understand the scheme of ditch arrangement in fortification structures of an early iron century settlement.

Keywords: georadar, archaeology, excavation, testing, mapping, fortification structures, buried ditch The Conservation Department of the Institute of Archaeology, RAS invited a group of the experts from IZMIRAN for the inspection of the excavation area of ancient settlement Nastasjino, located near Kolomna in Moscow Region. The excavation was carried out at the site of planned construction of a highway. By archaeological estimations, the age of ancient settlement was 2.5 thousand years. This period belongs to the epoch of early iron century. Human settlements of that time, as a rule, were surrounded by earthen fortifications for defense from militant forays of the neighbours. According to the archaeological assumptions, there were probably earthen ditches around the excavation buried by centuries-old agricultural activity. This version has been confirmed by an aerial photograph, on which concentric strips allocated by more saturated colour of the vegetation are distinctly visible (Fig.1). Archaeologists have suggested to investigate the northern sector of the territory with the help of GPR try, in order to find out the borders of buried ditches and to make a map of the underground structures. The inspection of the excavation area was carried out with the help of the georadar GROT [1,2]. Basic GPR characteristics are:
  1. Working frequency range 30 - 500 MHz.
  2. Pulse voltage on the transmitter's output 5 kV.
  3. Receiver sensitivity 75 mkV.
  4. Time resolution 1 ns.
This study was carried out with the help of the aerial set consisting of two resistive-loaded dipoles, 1 m long. The distance between receiver and transmitting aerials was 1.5 meters. Nine parallel profiles, with the length 50 - 60 meters each, were carried out. The distance between two next profiles was 3 meters. The measurements were carried out at direct contact of the aerials to the ground with a step of 10 cm (Fig. 2). There were executed hodographs in several essential points for finding the true depth of the layers, according to the well-known seismic method of "general excitation point". Two-layer geological structure, with an interface at the depth about one meter, was registered in all georadar scans executed across the excavation. The interface between two layers fell below this level on each GPR profile only in two places. The areas of the border descent, according to a radar-tracking image, were similar to a buried ditch. The sections of the "ditches" putted on the excavation scheme form sectors of circular strips with the width 5-6 meters and the radius from the settlement centre 20 meters, for the internal, and 30 meters for the external ditch. Preliminary analysis has given us a base to assume that the border registered by the georadar divides the upper cultural layer and the lower continental one, (according to archaeological terminology). The areas of the interface descent evidently correspond to the bottom of buried earthen fortifications ditches. This courageous assumption was confirmed during the subsequent excavation. (Fig. 3). The structure of the buried ditch with the depth of 1.7 meters from the present earth surface is well visible in the photograph. The bottom contour is distinguished by a layer of the condensed clay. It is possible to assume that "the ancient builder" laid these clay locks for water accumulation in the ditches. This trick of the ancient builder keeps its properties after 2.5 thousand years preserving the increased humidity of the ground which is detected by the vegetation and by GPR sounding. According to the results of georadar investigations and the excavation data, an artist has reconstructed the relief of this area and settlement constructions (Fig. 4). By the way, near the external ditch the archaeologists found a big quantity of arrowheads and lance tips during the excavation. All the arrowheads and lance tips had similar direction - from northeast to southwest - towards the fortress wall. This fact convincingly supports the above hypothes and our interpretation of the georadar data: the found objects were buried ditches, and the space between them was the base of earthen bulwarks. The results of GPR study of an archaeological excavation have shown that the georadiolocation can be useful for detection of such low contrasting interface, aged by several thousand years. The GPR application to archaeological research will essentially reduce time and volume of the excavation. The authors express their gratitude to the employees of the Conservation Department and Moscow Region archaeological expedition of the Institute of Archaeology RAS for supplying the experimental data and for the opportunity to test the georadar on an archaeological excavation.
  1. V.А. Garbatsevich, V.V. Kopeykin, S.Е. Kyun and А.Yu. Schekotov. Device for underground penetrating mapping. Patent Russian Federation, February 15 1994.
  2. V.V. Kopeykin, D.E. Edmsky, V.A. Garbatsevih, A.V. Popov, A.E. Reznikov and A.Yu. Shchekotov. Enhanced power ground penetrating radars. Proceedings of 6th International Conference on GPR. Sendai, Japan, 1996, v.1, pp. 515-517.
Fig. 1. Aerial photograph of the excavation area of ancient settlement Nastasjino
Fig. 2. Results of GPR inspection of the area around the excavation of settlement Nastasjino (4-3 centuries BC), Kolomna district, Moscow
Fig. 3. Excavation of buried ditch.
Fig. 4. Reconstruction of the relief near ancient settlement Nastasjino

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