Geodiversity, as diversity of the abiotic environment, includes terrain ruggedness (or roughness), which is one of the essential parts of geodiversity evaluation. The terrain ruggedness index (R) ...represents the value of one of the main geodiversity components. The purpose of the study is to discuss the characteristics of R in the scope of geodiversity, and to show how R differs within two specific study areas if we study them using a data scale that covers both areas and only site-specific data. Hence, the main methods include geodiversity element mapping, calculating R based on either the study area or broader-scale data and discussing the differences that arise. The findings show that R should not be calculated only within individual study areas if the results among different study areas are to be compared; rather, it should first be calculated on a larger scale for the whole region in which we are about to compare the specific study areas. The applied value of these results is that such data are then suitable for calculating the geodiversity index (G) according to specific methodological steps and for further analyses.
Monitoring of air temperature takes place at five locations in two cave systems. At monitoring location Velika gora (Postojna 1), mean air temperature for the time period 2009–2010 was 11.10 °C. Of ...three monitoring locations Velika gora is situated at the highest absolute height. Mean air temperature in the same period was 10.66 °C in the central part of the Lepe jame cave (Postojna 3) and 10.30 °C in the side passage (Postojna 2). Temperature difference between outside and cave temperature is the highest at Postojna 2 monitoring location, due to the inflow of the air currents from the unknown parts, especially in winter time. Manual temperature measurements (2004–2010) exhibit slight increase of air temperature at Postojna 1 and Postojna 2 monitoring sites. In the Predjama cave system, the air temperature in Velika dvorana is much more stable than in Konjski hlev passage, which is more subject to external influences.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Regarding the studied historic references there are sufficient proofs that during the 1st January 1926 earthquake (M=5.6) in Postojna cave system (Sala del Candore or Pralnica) a stalagmite column ...of 1 meter in diameter collapsed. This is a not so common event in karst caves and took place due to the close vicinity of the epicentre located at the SE end of Idrija Fault or at the Javorniki Mountain. During earthquakes in karst caves brontides are generally heard, but ground movement is rarely felt. Only strong and close earthquakes can be felt as ground shaking or waving inside the caves also, withsome possible collapses as well.
Mineralogical and chemical analyses of black coatings from two sites in Postojna cave system were studied. Scattered samples were taken from the entrance parts of the cave and from Črna Jama. Thin ...sections, powder X-ray diffraction (XRD) technique and scanning electron microscope coupled with energy dispersive X-ray spectrometer (SEM/EDS) were used. Microscopic investigation of thin sections of black coloured material from both locations revealed that the main material is carbonate – calcite, with evenly dispersed prevailingly minute opaque black grains. The XRD analysis on samples from both locations confirmed just a presence of calcite with minor quartz and dolomite, excluding Mn and Fe oxides or apatite-group minerals as reason for black colouring. The SEM/EDS analysis of samples from the entrance parts of Postojna cave system was consistent with XRD analysis, which did not show any Mn oxides. The high content of C measured in the black coatings from the cave entrance parts indicates organic C, which deposited on the cave walls at time of the petrol explosion during WW2. We can attribute black coatings from Črna Jama to one form of organic C as well, but it is certainly different from the one in the entrance parts of Postojna cave system. As in Črna Jama no other evidence indicates for old human inhabitation of the place: torches of first tourists are a more probable origin of charcoal. On both locations black coatings can be at least partly described by microclimate conditions at cave entrances, which caused the deposition of organic material of allogenic origin (for example soot due to the forest fires).
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