Geomorphological Conditions of the Genesis of the Ponor Jovac Cave (Croatia)

Abstract

Osrednji del slunjske kraške planote gradi prepustni zakraseli gornjekredni apnenec. Na njem leže v transgresijskem stiku denudacijski ostanki miocenskih peščenjakov in laporjev. Ta del površja je neprepusten z značilnostmi fluviodenudacijskega reliefa. Z morfološkega vidika je pomembna slepa dolina ponikalnice Džedinovac. Potok ponika na stiku miocenskih in krednih kamnin in teče dalje po glavnem jamskem rovu Ponora Jovac. Jama je dolga 689 m in je stalna pretočna oziroma občasna ponorna jama. Svet na apnencu je dobro zakrasel in brez površinske rečne mreže. Pač pa se slepa dolina Džedinovac nadaljuje s suho dolino, ki je morfološka sled nekdanjega površinskega toka potoka Džedinovac.

The middle part of the Slunj karst plateau is built of permeable karstified upper Cretaceous limestone. The Miocene sandstones and marls lie over them in transgressive contact in the form of denudation remains. This area is impermeable and has characteristics of fluviodenudational relief. In a morphological sense, the blind valley of Đedinovac periodical stream is remarkable. The Đedinovac stream sinks underground in the contact zone of the Miocene and Cretaceous rocks and continues its flow through the main channel of the Ponor Jovac cave. The Ponor Jovac cave is 689 m long and has the function of a permanent percolating and periodical sinkhole cave. The area built of limestone is well karstified and without a surface fluvial network. But in continuation of the Đedinovac stream blind valley a dry valley exists which is a morphological trace of the former surface flow of the Đedinovac stream.