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

Mieszkowski R, Dzierżek J., Stańczuk D.

Studia Quaternaria

2014

Vol. 31, Nr 2

73--81

The paper describes the results of geoelectrical sounding application for the 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 glacial till and structures composed of sand that have been recognized earlier in the 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.

Record and palaeogeographical implications of Pleistocene periglacial processes in the Drohiczyn Plateau, Podlasie Lowland (Eastern Poland)

Dzierżek J., Stańczuk D.

Geological Quarterly

2006

Vol. 50, No. 2

219-228

The paper describes 51 ice-wedge casts from Wierzchuca Nagórna village near Drohiczyn town in the Podlasie Lowland in Eastern Poland. The structures are preserved in a till of theWartanian Glaciation. In the exposure the mean distance between them is 1.7 m; their mean length is 1 m, and their width ranges within 0.2–0.5 m. Most of the structures are typically wedge-shaped, although in some cases less regular pockets or veins are also observed. Some of the casts display a complex origin. They are filledmostly by fine-grained sand, in the lower parts with wind-corroded grains, as well as by sand with gravel from the overlying deposits. Near the ice-wedge casts, traces of frost swelling, uplift and sorting in permafrost conditions, as well as of an active layer are preserved. The thickness of the permafrost active layer, as preserved, is about 0.5–0.7 m. The formation of ice-wedges reflects periglacial conditions during the Vistulian (Weichselian) Glaciation. Three palaeogeographical alternatives are discussed. Probably, the lack of traces of periglacial activity from the Wartanian Glaciation is a result of plateau denudation. The range of this denudation has also been estimated.