volcanic fissure in leirhnjukur, myvatn geothermal area in iceland with mineral orange soil around

active area blue caldera crack crater crevasse deep field fissure formation fumarole gap geology geothermal gorge hole hot spring hverir iceland icelandic land landmark landscape leirhnjukur mineral mountain mud myvatn natural nature opening orange outdoor ravine red rock soil solfataras stone sulfur sulfurous sulphating sulphur tectonic tourism tourist travel volcanic volcano