Parabolic Dunes of the Southern Nyírség

Abstract

A series of alluvial fans extend into the Carpathian Basin from the encircling mountains, and one of the biggest among them is the Nyírség, built by the Tisza River and its tributaries. In the late Pleistocene and Holocene aeolian processes reworked its surface, therefore sand dunes are the characteristic forms today. Approximately one quarter of the area of the Southern Nyírség is occupied by dunes, which form dune fields separated by former river courses. Although previous studies held parabolic dunes as the typical forms, only 6 % of the total dune area covered by filled, partially filled or unfilled parabolic dunes. Most of the dune area (ca 40 %) belongs to the valley-marginal dunes, which are associated with waterlogged paleo-courses and depressions. The rest of the features are transitional between straightened valley-marginal dunes and parabolic dunes. The present dune assemblage developed during the late Pleistocene, although due to human impact the sand was mobilized time to time, and smaller features (e.g. blowouts, hummocks) developed.