A carbonate breccia complex unconformably overlies limestones and dolomites, of middle to upper Triassic age, of the Veterlin and Havranica units. The clasts of breccia are angular and chaotically settled. They are petrographically consistent with the type of underlying limestones and dolomites. Speleothems and fluvially reworked gravels occur in the breccia complex. The greater part of the breccia complex is distinguished by a red coloured silt-clay matrix with increased content of Al₂0₃. The breccia complex was formed by the destruction of an extensive cave system, which was formed in the limestones and dolomites of the Veterlin and Havranica units at the end of the Paleoalpine phase, during the Upper Cretaceous or Paleocene.