V času med eocenom in pliocenom so bile s temena krednega apnenčevega antiklinorija v osrednjem in zahodnem delu planote Kras in s kozinsko-podgrajske antiklinale erodirane flišne plasti, zaradi ...česar se je ob splošnem zniževanju okoliške ravnine ob pogojih zajezenega krasa razširjal in zniževal ravnik na razkritih apnencih. Največji del planote Krasa predstavlja najstarejši del kraškega ravnika. Na Krasu so se v pliocenu in kvartarju pasovi ravnika hitreje zniževali v smeri proti SZ, vmesno zastajajoče ali dvigujoče se površje pa je s tem dobilo obliko vzpetin na severozahodnem robu planote. Zaradi hitrejšega grezanja vipavske sinklinale so vodni tokovi prenehali teči preko planote Krasa še preden je bil fliš, ki jim je preprečeval pot proti jugu, odstranjen zaradi grezanja severnega dela Tržaškega zaliva. Zaradi tega na Krasu ni slepih dolin ali polj. Pač pa je veliko vrtač, površje je kamnito, zaradi česar je iz Krasa nastal splošni pojem kras. Obe značilnosti sta tipični za submediteranske dinarske kraške ravnike, gosto naseljene in obdelane ter zaradi tega brez gozdov Between Eocene and Pliocene, erosion of flysch strata on the top of Cretaceous limestone anticlinorium in the central and western part of the Kras plateau and the Kozina-Podgrad anticline uncovered and widened – and simultanously lowered - the karst plain in the conditions of dammed karst. The largest portion of Kras plateau is covered with karst plain, its oldest part. In Pliocene, the karst plain was fractured and subsided towards the NW regardless of older folded structure; during this process, several zones of elevations were formed through slower subsiding or uplifting. Due to faster lowering of the Vipava syncline, water streams stopped running over the Kras plateau before the flysch, damming the waters from the Kras plateau to the south was removed due to the subsiding in the northern Gulf of Trieste. Thus, no fossil blind valleys or poljes are found on the Kras plateau. However, there is considerable density of dolines and the surface is stony, giving the karst its original name. Both phenomena are typical of deforrested, densely populated and cultivated Submediterranean Dinaric karst plains.
Geomorfogenetski procesi korozijskih vrtač so razpoznavni iz omejitev za njihovo globalno in lokalno razprostranjenost: več padavin kot znaša potencialna evapotranspiracija, prepustna odeja prsti, ...kraška vodna gladina in korozijska fronta (to je stik agresivne in sigotvorne vode) globlje pod površjem, površinski naklon pod 30°, kompaktna kamnina. Vrtače so posledica lokalno pospešene korozije. Njihov začetek je v lokalno bolj pretrti kamnini z večjo specifično (površina/volumen) površino, izpostavljeno koroziji talne vlage. Vpliv zdrobljenosti kamnine je bil potrjen z laboratorijskim poskusom. Poznejša rast kotanje sloni na avtomatizmu, ki izhaja iz večje stične površine prst/kamen kot jo ima začetna ravna površina (zdaj odprtina kotanje). Lijakaste vrtače se ob večanju kotanje običajno spremenijo v skledaste, kjer je preseganje večje. Na obliko vplivajo še prepustnost tal in soliflukcija. V zmernem podnebju je nudil dva milijona let dolgi pleistocen z večjo vlago iz snega in mehaničnim razkrajanjem kamna boljše pogoje za razvoj vrtač kot toplejša neogen in holocen, ko je človek bistveno skrčil primarno gozdno okolje in z njim procese v vrtači. Udornice niso upoštevane. Geomorphogenetical processes of solution dolines are evident from restraints in their global and local distribution: more precipitation than potential evapotranspiration, permeable soil cover, water level and solution front (transition from aggressive to flowstone depositing water) below shallow epikarst, slope inclination below 30°, solid soluble rock. Dolines are an effect of local accelerated solution. In initial phase they are connected with more fractured stone, as the grains have greater specific (surface/volume) surface exposed to soil moisture. Effect of stone fracturing on solution was tested in laboratory. Later growth of basin is based on automatism, as the size of soil/stone interface is increased with deepening of the basin. Funnel-like dolines with growth usually convert in a bowl-like form with greater exceeding. The form is controlled also by water permeability of soil and solifluction. In temperate climate the two million year long Pleistocene offered with more moisture from snow and with intensive fracturing of stone better conditions for doline development than the warmer Neogene and Holocene when man’s impact in last centuries essentially redused primary forest environment and thus processes in the basins. Collapse dolines are not taken into account.
Namen te študije je pokazati tektonske poteze v izbranih kraških poljih in manjših kotanjah Dinarskega krasa. Vrtine in gravimetrične meritve so ugotovile debele neogene nesprijete sedimente in ...apneniško dno pod gladino morja - kriptodepresije. Sedimenti so deli obsežne akumulacijske ravnine, ugreznjeni v kraška polja v spodnjem pliocenu. Seizmična aktivnost v sedanjosti nakazuje še trajajočo tektonsko aktivnost. Najgloblje (čez 100 m) in najmanjše kraško polje v slovenskem Dinarskem krasu, Globodol, je suho kraško polje v piezometrični vodni gladini. Pliokvartarno grezanje dna je edina možna razlaga za nastanek polja. Na Planinskem polju so znaki podtalne korozije in holocenskega tektonskega grezanja dna. Štiri kraška polja v Ravnih kotarih (Dalmacija) dokazujejo proces uravnavanja jezerskega dna pod plitvim pokrovom aluvialnih sedimentov. Izjemno globoke majhne kotanje so okoli 450 m globoko Rdeče jezero (Hercegovina) in kotanji pri Črnomlju in Kočevju (Slovenija), okoli 300 m oziroma 100 m pod gladino morja. The aim of this study is to show tectonic features in selected poljes and minor basins in the Dinaric Karst. Boreholes and gravimetric measurements show thick Neogene loose sediments and the rocky bottom below the sea level - real cryptodepressions. The sediments make parts of a large plain that subsided at the end of the low Pliocene. The recent seismic activity in this area proves the ongoing tectonic process. The deepest (more than 100 m) and the smallest polje in the Slovenian Dinaric karst, Globodol is a dry polje in the piezometric level. Quaternary subsidence of the bottom is the only reasonable explanation of its genesis. On Planinsko polje there are signs ob suballuvial corrosion and the indicators of the Holocene tectonic subsidence. Four poljes in the Ravni kotari (Dalmatia) are shallow basins in the first stage of development. They prove the process of the bottom levelling below the shallow cover of alluvial sediments. An extremely deep small basin is about 450 m deep Red Lake (Hercegovina) and small basins at Črnomelj and Kočevje (Slovenia), 300 m and 100 m deep below the sea level.
Geomorphology of Pohorje mountains GAMS, I
Acta geographica Slovenica : Geografski zbornik,
01/2008, Letnik:
48, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Pohorje mountain range, young mountains with prevailing metamorphic rocks and dacite, continues to uplift above the igneous laccolith in the area of the rapid rising asthenosphere in the ...transition to the Pannonian basin also due to changes in temperature and, resultantly, of the density of uplifting dacite- and other intrusions which have not metamorphosed the surrounding sediments. On the Pohorje by the river Drava (hereinafter the Drava Pohorje), the drainage network does not match the orography, because, between the Vuzenica-Radlje basin and Fala, the Drava epigenetically deepened its gorge into the marginal range of Kobansko. Modest plateaus on the ridge of the Pohorje originate from the time when the base level maintained a cover of the so-called Eibiswald strata between the Karavanke and the Kobansko in the upper Miocene. The originally larger ridge plateau in the centre of the Pohorje was lowered by erosion and periglacial processes; it has been preserved as an inclined plateau on the Eastern Pohorje. Explained through the recent tectonic shifting, established by means of GPS in the years 1996–2002 at the peak Velika Kopa, is the southeastwards curving of the five valleys above the Legen terrace where, supposedly, original headwaters of the Spodnja Mislinja came from. Due to its geological, geomorphological and hydrological peculiarities the Legen Quaternary terrace deserves that it should be declaired the ‘geopark’, the first one in Slovenia. Even more explicit and extensive is the westwards curving of the valleys on the northern slope of the Pohorje, and their northeastward orientation in the Ribnica-Lovrenc-Selnica valley system. In the east section of the Lovrenc valley system above Fala the brook Rečnikov potok has not adjusted its course to the recent tectonic subsiding, so that its valleys run obliquely to the slope inclination. The up to 700 metres deep Mislinja rift lowered the central ridge of the Pohorje to 1299 metres. Blowing intensely across it, the northeastern Pleistocene cold winds made possible the origination of two smaller glaciers in the upper drainage basin of the Radoljna. The gently sloping Pohorje landforms are not the result of the old age but of the disintegration of granular rocks to permeable sand, above which the thick cover of continuous roots of grasses and prevailing spruce reduces the erosion.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The relief of Bela Krajina and Semiška Reber in southeastern Slovenia is mainly a consequence of post Late Miocene tectonic movements and karstic, mostly subsoil, erosion. In the lower half of the ...slope at Vrtača in the northwestern part of Bela Krajina, 1.3 km northeast of the center of Semič and 15 to 25 meters above the surroundings, a 250-meter long and about 150-meter wide lateral ridge rises at an inclination of 8°. The formation of the medium-sized relief between the elevated lateral ridge and the lower elongated side depressions is most probably to a large extent the consequence of differences in the rock fissuring and the varying intensity of hundreds of thousands of years lasting corrosion related to it. Traces of subsoil formation are the prevailing feature found on hundreds of rock ribs (i.e., subsoil rock formations that are not cone-shaped like teeth but rather elongated with their longer axes largely parallel to the dip of the surface) dissecting the surface area of one of the vineyard plots on the rocky lateral ridge. This indicates they were relatively recently exposed, as a consequence of human activity when soil was removed from an abandoned plot.
Članek prikazuje dosedanji razvoj fizične geografije v Sloveniji kot dela kompleksne geografske vede, katere vrh so regionalnogeografske monografije Slovenije. Avtor vidi izziv za bodoči razvoj ...fizične geografije v Sloveniji v konkurenci več, močnejših in bolje opremljenih inštitutov s podobnimi delovnimi področji. Edino kvantitativno vrednotenje izbranih pokrajinskih pojavov lahko po avtorjevih izkušnjah ohrani geografiji že standardno in še vedno edino preostalo vlogo v domoznanskih prostorskih znanostih. Kljub večjemu zanimanju javnosti za družbeno geografijo pa zagotavlja tudi fizični geografiji pomembno vlogo 2-3-krat povečan vpis slušateljev geografije na v zadnjih letih še razširjeno mrežo visokošolskih ustanov.
The artice presents Dinaric karst, human impacts in the area, and its long history of deforestation, transformation into stony semi-desert, and a century long reforestation, where plans to restore ...the primary thick soil were just hoping against hope.
V planirani novi regionalni monografiji Slovenije naj bi bilo tudi Pohorsko Podravje predstavljeno v okviru mezoregij kot splet aktualnih regionalnih faktorjev in pri submakroregijah historični ...nastanek regionalnih prvin.
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