Collapse Structures as a Connection Between the Karst Surface and Underground (Examples from Croatia)

Na hrvaškem krasu je veliko udornic. So tudi take, nastale zaradi posedanja (subsidence). Analiziranih je nekaj geomorfoloških elementov in oblik, nastalih z udiranjem in posedanjem (vpliv geoloških okoliščin in stopnje jamskega razvoja na procese udiranja in posedanja, morfologija udornih in subsidenčnih vrtač ter jamskih rovov pod njimi), iz dveh jam z različnih delov hrvaškega krasa (Dolačina mama iz Žumberka in Jama na Sredi s Cresa). Opazovanja potrjujejo, da je podiranje pomembna sestavina v razvoju jam in da je nastajanje udornih in subsidenčnih vrtač pomemben pokazatelj razvojne stopnje krasa. In the Croatian Karst area there are a lot of collapse dolines. Here we can also find structures that are the result of subsidence (subsidence dolines). In the cases of two selected caves in different parts of the Croatian Karst area (Dolačina mama cave - Žumberak Mt. and Jama na Sredi cave - Cres island) some geomorphological elements and features of collapse and subsidence processes were analysed (the influence of geological conditions and the cave’s stage of development to wards collapse/subsidence the morphology of collapse and subsidence dolines and the cave passages beneath them). Observations confirm that collapse is a significant component of cave development and that formation of collapse and subsidence dolines is an important indicator of karst evolution.