Samples of sediment cores from two lakes in the karst area of northwest Yugoslavia were analyzed. Both Lakes Kozjak and Prošće are in the Plitvice National Park, Central Croatia. 14C dating, sedimentologic, seismic, and isotopic studies, and distribution of diatoms are presented.
14C dating of lake marl revealed a uniforn sedimentation rate in Lake Prošće as opposed to Lake Kozjak. Both lake sediments belong to the Holocene period. 14C dating of lake sediment is in agreement with seismic profiles, sedimentologic analysis, and diatom frequency measurements both in an undisturbed as well as in a disturbed lake sediment.