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 cave cavern caving chambers cracks damp dark discovery espeloelogo europe exploring formation geologist geology grotte grotto hell inside interior jama karst landmark light limestone mineral mountain mystic natural nature paradise postojna rock slovenia speleology stalactite stalagmite stone tectonic tourism travel underground water system