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With detailed lithological and tectonic-structural mapping at the scale 1:5000 we studied the area near Bukovje NE from Predjama. In the studied area and further towards the NE we can follow a strong thrust contact between Upper Cretaceous limestones of Snežnik thrust sheet over which Upper Triassic Norian-Rhaetian dolomite of Hrušica thrust sheet is overthrust. The thrust is cut by systems of dextral faults with expressed vertical component. Beneath the studied area underground passages of Predjama cave can be found; they are developed in limestones as in dolomites. Dolines in Upper Cretaceous limestone are uniformly arranged and are in structural-genetic view broken (D), near-fault (E) or fault (F). Along the thrust edge we have contact dolines (G) in dolomite. The rest of the dolines on dolomite are connected to differently broken rocks in fault zones and are called reproduced fault-broken dolines / HF(D)do /. For described karst features along thrust contact we suggest the name contact karst on dolomite along thrust.
Structural geological studies on karst areas operate with the same structural geological terms as on other geological regions. But because of special geomorphologic terms characterized for karst areas, some structural geological elements, which are in a special way connected with particular karst forms, are used as a special terms, different from those used on non-karstic areas. For Slovene karst we need to divide two most important structural elements that are important for development of cave passages, bedding planes and tectonic structures. And between bedding planes the ones that are tectonically disrupted are very favorable for development of initial cave passages. In the longest Slovene karst caves as Postojnska jama caves, Predjama and Škocjanske jame caves interbedded movements, thrusting and folding deformations, and tectonically broken zones (fissured, broken and crushed zones) are very favorable for initial, and also for older and younger stages of passage development.
For Western Slovenia moderate historical to recent seismicity is characteristic. The principal aim for Slovenia to join the COST 625 project was to exchange the experiences and methodology and in this way to determine the activity or non-activity of selected faults in Western Slovenia. Within the project frame we decided for several years of monitoring, and in this sense four TM 71 extensometers were installed in Western Slovenia. In the first half of the 2004 two TM 71 instruments were installed in Postojnska Jama on the Dinaric oriented fault that is situated about 1 km North from Predjama fault. The third instrument was installed on Raša fault on the SE slope of Vremščica and the fourth instrument in Učja valley on Idrija fault. The fifth instrument TM 71 will be set up on Kneža fault that is situated south from Ravne fault. The first results from Postojnska Jama are showing the small horizontal movements for 0.05 mm in one year.
The important regional thrust called Snežnik thrust, that divides the Snežnik thrust sheet from the parautochthon of the Komen thrust sheet, runs through the Pivka basin. A tectonic window near Knežak is proof of older thrusting deformations. The landscape is cut by numerous younger faults among which the most important are Raša, Predjama and Selce faults. The area of Upper Pivka is tectonically quite active, which is shown by earthquakes in recent years. It looks as if the most active is the Raša fault or one of its northern parallel faults, for example Šembije fault or maybe Selce fault. Karst intermittent lakes of Upper Pivka are developed in Upper Cretaceous limestones. The lakes are situated 0.5-4.0 km NE from the Snežnik thrust. Most of the lakes are situated along the Selce fault.
Imenski rov (Rov starih podpisov), the Old Cave (Stara jama), was the only part of Postojnska jama known for several centuries until 1818 when Luka Čeč discovered the access to the inner parts of the cave. Here we documented ca. 400 inscriptions. About 100 more were also recorded in the historic part of Predjama Cave. From these signatures we correlated 19 with independently historically known persons, less than 5% of the total. The correlation is firm for 15 names, but only tentative for Bellegarde, Kotze, Mihanović and Karl von Zur. The oldest one is that of Johann Melchior Ott(o) of 1642, a painter in the service of Johann Anton zu Eggenberg (1610–1649) the owner of the Castle of Adelsberg at the time, whose coat of arms Ott drew as well. The next oldest is the name Josef Anton Nagel 1748 who also left Latin inscriptions in Predjama cave and in Sloup Cavern, Moravia. All other inscriptions of historic persons are younger than 1800 including those of Franz Graf von Hohenwart, Joseph Petsch Ritter von Löwengreif and Alois Schaffenrath (each with several inscriptions). Noteworthy are also the signatures of Josef Franz Eggenhöfner (1801 or 1809, and 1820; developer of Grotta di Padriciano), Johann Natterer (biologist, 1815, who stayed 19 years in Brazil and laid the basis of the zoological department of the Natural History Museum in Vienna), Karl Beyrich (1819, botanist who died during an expedition in Arkansas, 1834), Giuseppe de Volpi (1820, from Trieste who published first evidence of the cave bear presence in Postojnska jama), Johann Fercher, mine supervisor, and his team of miners from Idrija who signed during their survey of the cave in 1833, Johann Ritter von Hauer (1836 in Pisani rov, Vienna, Imperial Councelor of War and Palaeontologist), Ivan Andrej Perko (the later director of the cave) and several cave guides. Members of the nobility or state employees include Bellegard, Adrienne Brandis Desenffans and her brother Karl Graf Desenffans, Carl von Kotze, and Mihanović.
High floods of September 2010 partly ruined historic inscription made by charcoal »Slovenski gadje 1882« in Predjama cave system. Regarding studied historic records the September 2010 floods were the highest in Predjama at least since 1882. If we thrust the well-documented floods in 1826 they can even be higher than ones in 2010. In 2010 the water reached 489.60 m above the sea level at entrance parts of the cave and about 485 m at Vetrovna Luknja causing that the old inscription from 1882 was under water and partly destroyed. Another old inscription »Nagel 1748«, probably done by more resistant pencil, did not suffer from the 2010 floods. Contrary, it was twice partly destroyed by carless visitors, first in 1991 and secondly in the period 1991 – 2005.
High floods of September 2010 partly ruined historic inscription made by charcoal »Slovenski gadje 1882« in Predjama cave system. Regarding studied historic records the September 2010 floods were the highest in Predjama at least since 1882. If we thrust the well-documented floods in 1826 they can even be higher than ones in 2010. In 2010 the water reached 489.60 m above the sea level at entrance parts of the cave and about 485 m at Vetrovna Luknja causing that the old inscription from 1882 was under water and partly destroyed. Another old inscription »Nagel 1748«, probably done by more resistant pencil, did not suffer from the 2010 floods. Contrary, it was twice partly destroyed by carless visitors, first in 1991 and secondly in the period 1991 – 2005.