Case Studies from the Dinaric Karst of Slovenia

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Case Studies from the Dinaric Karst of SloveniaAndrej Mihevc, Nadja Zupan Hajna, Mitja PrelovšekThe Dinaric karst (Dinarski kras) is themajor karst area of Slovenia. In past centuries,the Dinarski kras of Slovenia represented oneof the world’s prime sites of early scientificexploration of karst phenomena (Kranjc1997; Shaw 1992) due to the large number ofoutstanding karst features such as caves, largesinking rivers and flooded poljes. Speleology,karst hydrology and biospeleology were bornhere. The most prominent phenomena aresituated in the north-western part on theplateau named Kras. In Slovene language, krasmeans a rocky, barren surface. The name isoften used as toponym (Kranjc 1994, 1997). Krasplateau became a textbook example for thiskind of landscape because of the extraordinarykarst phenomena, and explorations done inthe 19 th Century. The name Kras in the Germanform of the word (der Karst) became aninternational scientific term. The area wherethese early explorations took place is calledthe Classical Karst (term introduced by Radinja1966, also 1972 as Matični Kras; which shouldnot be confused with the misinterpretation byŠušteršič 2000).The dominant relief features are ratherextensive levelled surfaces at differentelevations, large closed depressions (e.g.,poljes), and conical hills. Fluviokarst featureslike dells are common on dolomites. Karstrivers appear only in the bottoms of poljes,where they result from a high level of karstwater. Allogenic rivers flowing from noncarbonateregions either sink at the karstboundary, forming blind valleys, or cross thekarst through deep karst valleys and canyons.There are numerous extensive and complicatedcave systems formed by sinking rivers andconnected with the surface also by numerousvadose shafts. The surface karst morphology istypified by the abundance of karren, dolinesof various diameters and depths, sometimesextensive collapse dolines, cave entrances,unroofed caves, etc.For the Dinaric karst of Slovenia, twotypes of relief are characteristic: High Dinarickarst (high karst plateaus: Javorniki, Hrušica,Nanos, Trnovski gozd, Banjščice and Snežnik)and Low Dinaric karst (karst in the lowerparts: Notranjsko podolje, Pivka basin, Kras).There are presented limestones and dolomitesof Permian, Triassic, Jurassic, Cretaceous andPaleogene, cut by faults in the dominant Dinaricdirection (i.e., NW-SE). The most dominantkarst forms in the area are dolines, collapsedolines, karst poljes and high plateaus (Mihevc1997). The main factor in relief developmenthas been the dissolution process; others(fluvial erosion, slope processes, etc.) have asubordinate role. Along Idrija Fault the mainkarst poljes in Slovenia are developed: Loškopolje (Lož polje), Cerkniško polje (Cerknicapolje), Planinsko polje (Planina polje). Thereare many caves developed, among which is theoutstanding Postojna caves system with about20 km of known passages.49
KrasThe Kras is a distinct plateau, especiallywhen viewed from the seaward side. The Krastrends NW–SE between Trieste Bay, the northernmostpart of the Adriatic Sea, Vipava valleyin north-east, and the Friuli–Venezia Giulialowlands and river Soča in northwest (Fig. 40).The 45°45´´N and 14°00´´E lines of latitudeand longitude cross the Kras near Divača village.There are steep limestone slopes a fewhundred meters high rising directly from thesea or from the neighbouring lowlands to thenorthwest. Higher relief on flysch in the eastseparates the Kras from the Pivka region. Inthe southeast, the border of Kras is again welldefined by contact with the non-carbonateflysch of the Brkini hills and the valley of theReka river. Toward the south, the transition tokarst ridges and Matarsko podolje karst plateauis less obvious. The climate is sub-Mediterraneanwith warm dry summers. Cold winters,with most of the precipitation, show thestrong influence of the continent.The Kras belongs to the Adriatic–DinaricCarbonate Platform of the External Dinarides,composed of shallow marine fossil-bearingCretaceous and Palaeogene carbonates. Eoceneflysch rocks encircle the carbonate plateau.Kras and Matarsko podolje tectonicallybelong to Komen thrust sheet (Placer 1999),which is thrust over Eocene flysch and Palaeocene/Eocenelimestone of the Podgorski kras,a part of Kras imbricated structure (beforeknown as Čičarija imbricated structure; Placer2007). The whole structure is sub-thrust by theIstria unit.The main part of the plateau is essentiallylevelled, inclined slightly towards the northwest,with numerous dolines, caves and otherkarst features. There is a belt of slightly higherrelief in the central part of the plateau, formedby conical hills-like Grmada (324 m a.s.l.), Volnik(545 m a.s.l.) and Stari tabor (603 m a.s.l.), anddissected by large depressions. The higherrelief divides the Kras into two separatedlevelled surfaces. The southern one is namedNabrežinsko podolje. In the northwestern part,the plateau descends to below 50 m a.s.l. onthe edge of the Friuli Plain; on its south-easternedge altitudes are about 500 m a.s.l There areabout 300 m of accessible vadose zone withcaves formed at all altitudes from the surfaceto the sea level and below it. No superficialstreams occur on the Kras surface because allrainwater immediately infiltrates to carbonaterocks. There are two dry valleys crossing theplateau and some NW–SE-trending belts oflower relief which were believed to representprimary river valleys also because they containremnants of fluvial sediments dated to a prekarstificationphase (Melik 1955; Radinja1985).Geomorphologic and speleogenetic studiesand especially new interpretations of fluvialsediments from the Kras surface as the fluvialfill of now unroofed caves have enabled a newexplanation of the evolution of the Kras (Mihevc1996, 1998, 1999a-c, 2001b, 2007; ZupanHajna et al. 2008a).Nabrežinski krasNabrežinski kras (Nabrežina Karst) is thenorth-western part of the Kras around thevillage of Nabrežina (Aurisina in Italian). It isonly about 150–180 m a.s.l. There are severalold collapse dolines on the surface, morethan 300 m wide and to 50 m deep. Smallersolution dolines are less abundant, most ofthe surface having plain or slightly undulatingrelief. Toward the north-east, the surface ofthe Nabrežinski kras gradually transforms intothe slopes of the Volnik (545 m a.s.l.) hills andGrmada (324 m a.s.l.). An abrupt change of50
Page 2 and 3: Andrej Mihevc, Mitja Prelovšek, Na
Page 4 and 5: ContentsGeographical Position and G
Page 7 and 8: Fig. 2: Coastal part of Dinaric kar
Page 9 and 10: ogy started. In 1531 a lawyer from
Page 11 and 12: include numerous data and general o
Page 13 and 14: GeologyNadja Zupan HajnaThe Dinaric
Page 15 and 16: ceous. The final disintegration of
Page 17 and 18: Fig. 11: Locations of Jelar Breccia
Page 19 and 20: ClimateMitja PrelovšekThe Dinaric
Page 21 and 22: 311 mm/a; Zaninović 2008) and incr
Page 23 and 24: 24Fig. 16: Spatial distribution of
Page 25 and 26: ocks (such as Eocene flysch, Lower
Page 27 and 28: absent. Downstreamparts of the cany
Page 29 and 30: GeomorphologyAndrej MihevcIn folk l
Page 31 and 32: long. They are smoother especially
Page 33 and 34: is now depositing. Best known are t
Page 35 and 36: Structural poljes are dominated by
Page 37 and 38: Fig. 28: Typical dolines of Dinaric
Page 39 and 40: the disintegrated collapsed rock at
Page 41 and 42: on Northern Velebit, where three ca
Page 43 and 44: Land UseNadja Zupan Hajna, Andrej M
Page 45 and 46: for ‘bare limestone desert’ -th
Page 47: Fig. 38: Grančarevo dam in the upp
Page 51 and 52: in this part of the Kras (Mihevc 20
Page 53 and 54: dolomite barrier along the Idrija w
Page 55 and 56: of Dolenjska (Gams, 1974; Kranjc, 1
Page 57 and 58: Fig. 44: Blind valleys of Matarsko
Page 59 and 60: ly several dozen meters deep. Shaft
Page 61 and 62: smaller than the higher ones. The r
Page 63 and 64: tion in the Divaški kras (Mihevc 1
Page 65 and 66: Use of Karst and its ProtectionThe
Page 67 and 68: Gams, I., Vrišer, I. (Eds.), 1998:
Page 69 and 70: lems.- Dela 38, Raziskovalni center

Case Studies from the Dinaric Karst of Slovenia

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