Notranjski Kras

Notranjska Karst

Image: overview map of the Notranjska Karst located at the entrance of Postojnska Jama.

Notranjska is a heavily karstified triangle between the Ljubljana Basin to the north, the Gulf of Trieste to the southwest and Kvarner to the southeast The central Notranjska karst area is located around Postojna, Planina and Cernica. There are different definitions about what belongs to Notrjanska, some tell that it is the whole area also called Notrjanska Classical Karst. However, we found that the term today is used moer or less for the area around Postojna, including also some nerby sights like lake Cerkniza. On the other hand there is the Classical Karst, which we define as the area around Trieste.

The whole area shows numerous cave systems, dolines, swallow holes, seasonal lakes, and karst springs. There is a typical change between insoluble flysh lowlands and soluble limstone ridges. Rivers leave the surface, as soon as they reach the limstone and disappear underground, just to reappear a few kilometres away behind the ridge.

The most famous cave system is the underground bed of the Pivka river. This cave system is enormous, more than 20km long and with numerous entrances in the whole area. In former times, when the people knew nothing about the connection of the caves, they gave every entrance its own name. Several cave entrances where developed as independent show caves.

This area has a long speleologic history, the first known visit of the cave happened already in the 13th century. During the renaissance, in the 16th century, visitation and exploration of the cave boosted. The Postojna branch, better the upper level of Postojna Cave which is visited today, was discovered in 1818. The first light system was installed in 1818 using gas. Then the cave had the first electric light of all caves in the world, which was installed in 1884.

The reason is easy: the southern entrance of the cave system is really huge. The cave is big and rather easy to explore, you just walk in. And there is the history of the area. Slovenia belonged to the Austrian Hungarian Empire, an enormous multi cultural empire unique in history. So there was the possibility for famous geologists from all over Europe to visit and explore the cave.

The whole cave system of Postojna has several entrances:

Postojnska Jama.
The biggest part of the system gave the whole system its name.
Crna Jama (Black Cave).
Pivka Jama (Pivka Cave).
Crna Jama and Pivka Jama are connected by an artificial tunnel and are together accessible to the public.
Magdalenska Jama (Magdalena Cave).
This cave is only open to speleologists. It is just mentioned as it is an important part of the Postojna system.
Otoska Jama (Otok Cave).
Though not connected with the cave system, this nearby cave definitely belongs to the Postojna system.

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