Jan Dzierżek

Application of geoelectrical profiling in the delineation of shallow periglacial structures on the Drohiczyn Plateau

Abstract The paper describes the results of geoelectrical sounding application for delineation of periglacial structures in Wierzchuca Nagórna within the Drohiczyn Plateau (eastern Poland). The method records the variation of apparent resistivity of deposits along a selected horizontal direction. The survey utilizes a distinct geoelectrical contrast between a glacial till and structures composed of sand that have been recognized earlier in a gravel pit wall. The studies have been conducted in direct hinterland of the gravel pit. Rectangular and concentric arrays were applied in the survey. The results have been presented as graphs and resistance distribution maps. The obtained geological image is not complete, although it shows an oriented course of the largest lineaments and traces of a network with a small mesh size (1.5-2 m). The recognized pattern of structures points to harsh climatic conditions during their formation. General orientation of the structures corresponds to the basic elements of the contemporary landscape in the area (slope, valley axes). Geoelectrical sounding using the rectangular array gave better results than in the concentric array, whereas introduction of brine into the system did not enhance the resolution of the readings. The presented resistance distribution maps with a characteristic rhythm of variations may serve as a benchmark for recognizing periglacial structures in areas without exposures.