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

Na hrvaskem krasu je veliko udornic. So tudi take, nastale zaradi posedanja (subsidence). Analiziranih je nekaj geomorfoloskih elementov in oblik, nastalih z udiranjem in posedanjem (vpliv geoloskih okoliscin in stopnje jamskega razvoja na procese udiranja in posedanja, morfologija udornih in subsidencnih vrtac ter jamskih rovov pod njimi), iz dveh jam z razlicnih delov hrvaskega krasa (Dolacina 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 subsidencnih vrtac 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 (Dolacina 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.