Speleological Features in the Mountainous Karst of Risnjak Mountain (Croatia)
Nenad Buzjak, Suzana Fiedler - (28/1,1999)
Risnjak mountain is located in western Croatia. Its central area is, together with the nearby Snjećnik mountain and the upper part of the Kupa river valley, a part of Risnjak National Park. Since it is mostly built of heavy broken Jurassic carbonate rocks (limestones predominate), all kinds of karst features are well developed. Among exokarst forms dolines predominate. Among speleological features shafts are the most frequent forms. There are several morphological types of these in the altitude range between 680 and 1520 m. Although the deepest shaft explored to date is 180 m deep, the rest of the shafts are mostly up to 50 m deep. Consistent with high altitude and a severe climate thick beds of snow and ice were found in a few shafts. Near the southeastern border of the National Park area there are a few streams which flow over the less permeable Triassic dolomite beds and impermeable Triassic and Permian clastic beds. They sink at the contact with permeable carbonate beds. Among their ponors the largest is Vele Vode ponor cave which is 1495 m long.