The book is the obvious complement and continuation of the first part, which was published in 20131. One must emphasize that the two volumes are intended to be just the beginning of a series of ...similar publications that will cover all important karst regions in Britain. As before, the actual, paperback issue (hardback is also available) is in A4- format. In the future both volumes will be accessible as electronic versions, and some of the digital chapters will undergo revision if significant discoveries or scientific breakthroughs are made.
Podan je inventar denudiranih globoko freatičnih jamskih oblik, ki se danes pojavljajo na kraškem površju v Laškem Ravniku (vzhodno od Planinskega polja). To so denudirani delno izprani kanali, ...denudirani z ilovico popolnoma zadelani kanali, zaplate ohranjenega polnila izbrisanih jam, konglomerat in siga. Možen izvor polnil je v porečju Cerkniščice. Organizacija jamskega spleta se sklada s Ford-Ewersovim modelom in nakazuje pravilnost nekaterih spoznanj R. Curla, S.Worthingtona in D. Loweja. An inventory of denuded and exhumed deep phreatic cave forms that have been detected on the karstified surface of the Laški Ravnik (east of Planinsko polje, Slovenia) is presented and described. Features observed include denuded completely-filled channels, washed-out channels, accumulations of cave loam (originating from caves that are now completely destroyed), conglomerate and flowstone. The source area for the sedimentary infills might be the Cerkniščica river catchment. Cave patterns revealed by the study fit well to aspects of the Ford-Ewers’ cave development model, and also indicate the validity of some of the observations made by R. Curl, S. Worthington and D. Lowe.
Namen članka je pokazati, da ne obstoji samo prostorska domena, kjer podzemske kraške oblike sistematično prehajajo v nekaj drugega in izginjajo, ampak tudi, da lahko na osnovi tega znanja kraške ...votline trdneje vpnemo v logični okvir geospeleološkega prostora/časa. Prava kraška jama je vsaka podzemska kraška oblika, ki je nastala kot posledica odnašanja mase v raztopini, ob pogoju, da je trajekrotorija vodnega toka, ki jo je izoblikoval, tekla skozi (jamo), ne glede na njene izmere. Speleogenetski prostor definiramo v tem kontekstu kot tisti del Zemljine skorje, v katerem lahko nastajajo kraške jame. Tedaj je zakrasela kamninska masa aktiviran speleogenetski prostor. Zaradi denudacije in zniževanja gladine podtalnice se zdi, da posamezna jama po speleogentskem prostoru potuje navzgor, dokler ne doseže površja. Kraška denudacija deluje navpično in prizadeva matično kamnino znotraj cele vrhnje plasti, isto pa seveda velja za vse oblike znotraj kamnine. Zato lahko uvedemo pojem speleotanske cone. Znotraj nje je napadena vsa kamnina, na vsaki možni površini in končna posledica je njeno popolno izničenje. Slično razgradnjo bodo v stiku z agresivno vodo doživele vse strukture v kamnini, ne glede na izvor. Glede na značilno oblikovanje/razgrajevanje kraških votlin lahko znotraj spelogenetskega prostora definiramo tri speleoformativne/de-formativne cone. The point of this paper is to demonstrate that not only the spatial domain where underground karst phenomena are being systematically transformed exist but also that this knowledge makes the role of caves within the geospeleological space/time more consistent. A true cave is any underground karst feature resulting from mass removal, regardless of its dimensions provided that the trajectory of the formative water passes through the cave and that the mass is removed in liquid phase (solution). Speleogenetic space is defined as that portion of the Earth’s crust within which karst caverns may be formed. Thus, a karstified rock mass is defined as activated speleogenetic space. Due to the effects of denudation and watertable lowering, as the time passes a single cave seems to move upwards through speleogentic space, until it reaches the surface. The denudational logic of the karst surface is vertical, and the rock suffers disintegration throughout the thickness of its outermost layers. The same argument applies also to in-rock features. Consequently, the idea of the speleothanatic zone is introduced. Within it all of the rock is attacked, on any possible surface, and the final result is its complete annihilation. It may be expected that all structures, of any origin, that expose the rock surface to contact with aggressive water, will evolve via some “speleothanatic” progression. It is demonstrated that three vertical zones of specific formative/de-formative processes exist within speleogenetic space.
Razprava teče o udornicah, enem na videz najbolje definiranih površinskih kraških pojavov. Kljub temu je v literaturi zaslediti zelo različne poglede, nekateri vidiki njihove geomorfogeneze pa so ...bili doslej prezrti. Predvsem gre za za nadalnji razvoj globeli v kraškem površju, potem ko so prepadne stene udornice že uničene, pobočja oblikuje samo še žepasto preperevanje, denudacija pa se je zajedla že globoko pod dno nekdanjega jamskega rova. Take globeli imenuje avtor fantomske udornice. V nadalnjem obravnava pet v Sloveniji najbolj običajnih tipov udornic in jih klasificira s pomočjo terminologije splošne teorije sistemov. Zaključuje, da sam udor stropa ostaja bistven del celotnega procesa, je pa volumsko lahko zelo podrejen. The paper concerns collapse dolines, which appear to be one of the best-defined surface karst phenomena. Despite this appearance, one may find quite different views in the literature, and some the aspects of their morphogenesis have been overlooked completely. Among these aspects the most obvious is the question of the ongoing development of the closed depression. After the perpendicular walls have disappeared, the slopes are reshaped only by pocket weathering, and denudation penetrates deep below the former level of the preexisting cave floor. Dolines at this stage of development have been termed phantom collapse dolines. Five of the most common collapse doline types found in Slovenia are considered in terms of general systems theory, leading to a conclusion that cave roof collapse remains the crucial event in a collapse doline’s development. However, the collapse event itself may be relatively subdued in terms of the volume of free fallen mass involved.
Dvorana v Breznu pri Medvedovi konti (Pokljuka) je s svojim razponom okrog 150 m, višino prek 50 m in prostornino 62,0 × 104 m3 druga največja znana v Sloveniji. S pomočjo računalniškega programa ...FLAC smo modelirali stabilnost oboka pri hipotetičnem denudacijskem tanjšanju stropa. Uporabili smo dva nabora mehanskih parametrov kamnine. V obeh primerih so deformacije v stropu najmanjše pri debelini stropa 20 m do 30 m, do zrušenja pa pride pri debelini okrog 4 m. To dobro ustreza terenskim opazovanjem delno zrušenih jamskih dvoran. Skladanje z realnostjo nas opogumlja k nadalnjim simulacijam. The big chamber in Brezno pri Medvedovi konti (Julian Alps, Slovenia), about 150 m wide, over 50 m high and with a volume of about 62 x 104 m3, is the second largest cave chamber yet discovered in Slovenia. Application of FLAC computer software enabled modelling of the stability of the chamber’s arched roof during hypothetical denudational lowering of the overlying surface. Modelling was based on two sets of rock property parameters generally attributed to the local parent rock. In both cases the modelled deformation within the arch was at a minimum at a residual ceiling thickness of 20 to 30 m, whereas collapse occurred when the residual ceiling thickness reduced to about 4 m. These modelling results fit well with field observations of partly collapsed cave chambers.
Podrobna raziskava gornjega porečja Cerkniščice in njenih sedimentov v Cerkniškem polju je pokazala, da se je rečica v kotanjo polja pretočila šele srednjem Würmu, medtem ko je bil dotok v Cerkniško ...polje (in ponorne jame) dotlej popolnoma kraški. Njen vršaj je odrezal severne ponore in preusmeril glavni dotok s polja proti zahodu, posredno na Planinsko polje. Zato so današnje hidrološke razmere v Planinski jami neposredna posledica dogajanj na Cerkniškem polju. Detailed study of the upper Cerkniščica’s catchment and its sediments in Cerkniško polje revealed that the river turned this direction in the middle Würm, while in the more remote past, the input to Cerkniško polje (and to the caves) was completely karstic. Its alluvial fan cut the main vertical ponors, and deflected the main polje outflow westwards, indirectly into Planinsko polje. Consequently, recent hydrogeological conditions in Planinska jama are a direct consequence of development in Cerkniško polje.
Progress in the understanding of cave genesis processes, as well as the intensive research carried out in the Alps during the last decades, permit to summarize the latest knowledge about Alpine ...caves. The phreatic parts of cave systems develop close to the karst water table, which depends on the spring position, which in turn is generally related to the valley bottom. Thus, caves are directly linked with the geomorphic evolution of the surface and reflect valley deepening. The sediments deposited in the caves help to reconstruct the morphologic succession and the paleoclimatic evolution. Moreover, they are the only means to date the caves and thus the landscape evolution. Caves appear as soon as there is an emersion of limestone from the sea and a water table gradient. Mesozoic and early tertiary paleokarsts within the alpine range prove of these ancient emersions. Hydrothermal karst seems to be more widespread than previously presumed. This is mostly due to the fact that usually, hydrothermal caves are later reused (and reshaped) by meteoric waters.
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