Pivka Jama

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Pivka Jama

The Pivka Jama (pronounced: Pjuka Jama, German : Poik cave) is a karst cave in southwestern Slovenia that is open to tourists . It is part of the cave system created by the Pivka River , the most famous part of which is the Postojna Caves .

Position and extent

The Pivka Jama is about 3 kilometers north of the city of Postojna . It is accessed from a campsite, which offers daily cave tours, and is the largest of the natural shafts found in the Slovenian Karst area. The approximately 60 m deep shaft is accessed by a staircase built in 1925 with more than 300 steps that lead in several bends to the bottom. There is the entrance to the cave at the foot of the rock face.

In the cave the Pivka flows through a system of crevices and chambers, some of which are covered with stalactites. The water flows into the river in the Pivka Jama in two arms. The so-called Perko-Gang branches off from the course of the Pivka shortly before the Magdalena Cave, an entrance to the Postojna cave system west of the Pivka Jama, and then flows through the lowest level of the Črna Jama (Black Cave), another through a Natural shaft accessible part of the cave system. This arm is connected to the Pivka Cave by a siphon . The other arm of the Pivka flows through the Magdalena Cave; it is also connected to the Pivka Cave by a siphon. In the Pivka Jama, both arms unite and flow in a northerly direction past the entrance of the cave, only to disappear into another siphon a short distance behind it. The waters of the Pivka only reappear in Planina, more than two kilometers from the Pivka Jama. A 950 m long part of the connecting cave part has already been explored by cave divers, a further 1,500 m are not yet known (as of 2007).

The sightseeing route leads upstream in a southerly direction, first through some larger halls, then on the edge of the Pivka along a path cut into the rock face in 1925. The southern end of the Pivka Jama is connected to the Črna Jama by a short tunnel, in which another artificial tunnel, normally closed by a gate, provides access to the Postojna Caves. The current cave tour leads through the Črna Jama and reaches daylight again at its exit (status 2008).

Emergence

The Postojna cave system is the upper part of the catchment area of the Ljubljanica , which is strongly shaped by the karst, and has been created by the Pivka, the main drain of the Pivka basin and its subterranean tributaries, at least since the early Pleistocene . Dating of the sediments deposited in the cave system showed an age of up to 0.9 million years. The formation of the caves is related to the fact that on the southwestern edge of the Pivka Basin, the less permeable Eocene flysch in the basin below borders against thick layers of chalk , which are often very pure limestone, which is much more dissolved by water than the sandstones and mudstones of the Flysch.

The water, which initially ran off the surface, penetrated the limestone along fissures and fault zones and led to the formation of caves that allowed the water network to be shifted underground. This process was supported by tectonic processes, which led to the sinking and rising of the geological units against each other, so that the water had to constantly look for new paths. The active cave sections were also expanded by the masses of sand, gravel and rubble carried by the Pivka and its predecessor rivers.

The course of the cave passages of the Postojna cave system shows two main directions. A large part of the corridors runs clearly in a north-west-south-east direction and thus parallel to tectonic faults in the cave area. A second part is approximately perpendicular to it and is more branched than the other part.

In areas where the limestone is not very resistant - for example in fault and crevice zones and especially at the intersections of such zones - the cave ceiling can repeatedly collapse, which in many cases eventually reach the surface of the earth and form sinkholes there. If the underground water can remove the debris, the sinkhole will be cleared as far as possible. One such case is the Pivka Jama, where rock walls up to 60 meters high have formed in the hard limestone, at the foot of which an opening leads to the Pivka cave.

History of exploration

While the Postojna Caves had been known nationwide since the 16th century and their tourist development was vigorously promoted from 1819 and so did the Črna Jama (then still called Magdalena Jama, the current name of another shaft cave in the vicinity) through the discovery of another The presence of the olm in this cave in 1797 by Josip Jeršinovič von Löwengreif enjoyed a certain fame, the Pivka Jama received little attention due to its difficult access. Only Adolf Schmidl explored in his 1852 published studies a total of 5,250 m of underground river running of the Pivka by penetrated it from the main entrance of the Postojna Cave as well as from the Pivka Jama and Jama Planina in the cave system. In 1854 he gave a brief description of the part of the Pivka Jama that he examined in 1850, which was then not very widely accessible, as well as a description of a second visit in 1852, during which he and his companions could advance 150 fathoms downstream and 500 fathoms upstream . He was so taken with the sintered formations of the Pivka Jama that he wrote:

“ If any cave in Carniola deserves to be made accessible, it is the Piuka Jama. The Adelsberger Calvarienberg, the lake in the Planina cave and the Dolenz gate in the Piuka Jama are without a doubt the highlights of the cave world there! "

In Schmidl's time, the construction of a railway tunnel through the cave system was discussed, but this was not implemented because of the above-ground line Ljubljana - Trieste opened in 1857.

A connection between the Postojna Caves and the Pivka Jama could not be proven by Schmidl, and the investigations by Franz Kraus , who wanted to establish this connection from the Pivka Jama in 1885, were unsuccessful due to the autumn floods that set in early that year. The subterranean course of the Pivka was explored in 1893 by Édouard Alfred Martel and members of the Anthron Society, an association of speleologists from Postojna, via the Otoska Jama to today's Magdalena Jama, and finally, as part of Martel's explorations, the connection of the Magdalena Jama proved to be Pivka Jama.

After the First World War , the hinterland of Trieste was added to Italy. Due to its location on the border with the Kingdom of Yugoslavia , galleries and tunnels were built by the Italian military in the 1920s, connecting the Postojna Caves, the Črna Jama and the Pivka Jama. A continuous connection to the Planina cave was planned as a gateway from Italy to Yugoslavia. However, due to technical difficulties, this connection was never completed. In 1929, the Pivka Jama was equipped with electric light as part of the installation of a new lighting system in Postojna Cave. In 1944, the connection between the caves created in this way was used by Yugoslav partisans to reach a German gasoline depot built at the entrance to the Postojna caves and set it on fire.

literature

Web links

Individual evidence

  1. ↑ a b c Marcel Lalkovič: The cave in Postojna in Slovak literature before 1918 . Acta carsologica, 30/2, 19, pp. 267-277, Ljubljana 2001
  2. ↑ a b France Šušteršič: Relationships between deflector faults, collapse dolines and collector channel formation: some examples from Slovenia. International Journal of Speleology, Vol. 35, No. 1, pp. 1-12, Bologna, January 2006
  3. ↑ Stanka Šebela, Ira D. Sasowsky: Age and Magnetism of Cave Sediments from Postojnska jama cave system and Planinska jama cave, Slovenia. Acta carsologica, Vol. 28, No. 2, pp. 293-305, 1999
  4. ^ Francois numbers (ed.): Vulnerability and Risk Mapping for the Protection of Carbonate (Karst) Aquifers. European Commission, Directorate General, Science, Research and Development, 2003. ( PDF, 5 MB  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice . ) Map of the cave system on p. 10@1@ 2Template: Toter Link / www.bgr.bund.de  
  5. ↑ Schmidl 1854, p. 111 ff. And 301 ff.
  6. ↑ Schmidl 1854, p. 305
  7. ^ Trevor R. Shaw: Early electric lighting in caves - Postojnska jama, Slovenia, 1883-1929. Acta carsologica, Vol. 32, No. 1, pp. 189-204, 2003

Coordinates: 45 ° 47 ′ 56.6 "  N , 14 ° 12 ′ 24.4"  E