the water boils in many mud caverns, fumaroles, where steam and gas penetrate the cold icelandic air

water boils mud caverns fumaroles steam gas penetrate cold icelandic air yellow sulfur stains place result crystallization earth minerals bedrock geothermal field covers area approximately km² springs located 100 wide belt runs direction tectonic lines south south-west 500 long 100m place bedrock km² south-west 500m