fascinating stalactites and stalagmites in postojna cave, slovenia

cave formation caving quail stalagmite geology stalactite tunnel trunk rock wadi tree darkness canyon terrain ice wood person fascinating stalactites stalagmites postojna slovenia millions years karst phenomena generated wonders extend kilometers underground slovenian ancient archeology awe beautiful calcium cavern chambers cracks damp dark discovery espeloelogo europe exploring geologist grotte grotto hell inside interior jama landmark light limestone mineral mountain mystic natural nature paradise speleology stone tectonic tourism travel water system