The South-Eastern Nida Basin (Ponidzie)—Karst in Gypsum Rocks

The south-eastern part of the Nida Basin region is the only area in Poland of gypsumGypsum karst development. Karstification, developed in several areas of the region, occurred in a 30–40 m thick gypsumGypsum series of Miocene age. The most specific karst area within the Nida Basin is the western part of the Solec Basin, with large karst-denudational depressions, karst blind valleysBlind valley, ca. 100 caves as well as several clusters of dolinesDoline. The large karst-denudational depressions represent senile landforms, whereas karst valleys, most caves and dolinesDoline are young morphological features, of Late Pleistocene or Holocene age. They are genetically connected with the present-day water table and are classified as open karst. In the Szaniec Plateau, depressions (dolines, swallow holes) and valleys are the most typical karst landforms, while caves are practically absent. They mainly represent subjacent karst, since the gypsum series is still covered by younger rocks over most of the area. In other areas, gypsumGypsum karstification represents intrastratal karst that has developed and currently develops under the impermeable clays and claystones overlying gypsum series. Genetic differences of gypsumGypsum karst and their geomorphic consequences decide about scientific importance, whereas the occurrence of open, currently active karst in the Solec Basin has high educational value.