Grizzly Fumarole

Grizzly Fumarole changes from day to day and season to season, reflecting recent weather conditions. During dry weather, steam rises from its mostly dry vents, but rain or snow transforms it into mudpots, and a single, large mudpot often appears in spring. A fumarole, or steam vent, has an underground system that is nearly dry, where water heated deep below the surface turns to steam and rises with other gases. Mudpots are muddy springs where microorganisms convert hydrogen sulfide gas from Yellowstone’s magma chamber into sulfuric acid, which breaks rock and soil into mud. More broadly, Yellowstone’s hydrothermal features form when rain and snow seep into the ground, are heated by the magma chamber, and rise to the surface as a geyser, hot spring, mudpot, or fumarole under extreme water pressure.

Wyoming · United States