The underground world of karst: Speleology
There are about a hundred caves and pits along the course of the Krka River, some 40 of which are within the boundaries of Krka National Park.
The largest number of cave structures has been recorded in the Promina deposits and Upper Cretaceous rudist limestone. These structures were created from tectonic fissures that expanded over time under the corrosion and erosion influences of water. Cave structures from the Quaternary also include travertine barriers and are typically of smaller dimension.