Osobliwe formy poligonalne na łąkach w dolinie Wieprza

Abstract

Peculiar polygonal markings on·the meadows in the Wieprz river valleyDuring the author's geological and geomorphological investigations in the area of the Lublin Upland a regular polygonal (penta- and hexagonal) network of crackings was found by him on the meadows of the valley of the Wieprz and its tributary Stawek, in the neighbourhood of the village Zakrzew. The crackings are of 1,5-3 m in diameter (s. fig. 1, 2). They are very similar to the polygonal network found in the arctic tundra (e. g. to the fissure polygons in Greenland and Spitsbergen). These crackings were formed in the following circumstances. The meadow, on which they appear; was a pond until 1944. After the dam was destroyed during the last year of the war, the water flowed down rapidly and the surface of the bottom, coated with a thick silt layer, dried up very quickly and formed the network·referred to. This phenomenon proves that the markings formed through drying·are similar to those which are produced by the action of frost. The main difference consists in their surfaces: the forms of drying action have a flat and even surface, those of the action of frost have a convex surface. The author also describes another type of meadow markings in the neighbourhood of Ciechanki on the river Wieprz. The meadow is filled with mounds 20-40 cm high, often bell-shaped (fig. 3) . They recall the "bugry" of the Russian tundra, the "palsen" of the finish tundra and the "thufurs" of Iceland, but, according to the author, they were pressed out by the pasturing cattle. Among the forms of the meadow microrelief in Poland discussed, the author quoted the following: 1) mounds arising from the volume alternation of green turf mass by frost action (after Brandt and Lozi:6ski), 2) green turf mounds which were formed in connection with turf lenses in the area of highland peat-bogs, 3) cattle mounds, mentioned above, 4) mole-hills raised on the dry meadows, which, when covered by vegetation, are very similar to the first group.