Hot springs Fumaroles-a geothermally heated opening in the Earth where steam and hot gases are expelled. Solfataras (Italian name)-relatively cool fumarole that(l00°Cand300°C)that give off hydrogen sulfide that reacts with the oxygen in the air to produce sulfur deposits.Hot Springs • Fumaroles - a geothermally heated opening in the Earth where steam and hot gases are expelled. • Solfataras (Italian name) - relatively cool fumarole that (100°C and 300°C) that give off hydrogen sulfide that reacts with the oxygen in the air to produce sulfur deposits