Cooking Hillside

Managing agency

National Park Service

The trees on this hillside are cooked by steam. In 1978, an earthquake swarm occurred at Mud Volcano. The intense swarm lasted about seven months. This hillside experienced increased heat, causing the vegetation to die. Researchers are able to study tree rings to learn about past earthquake swarms and other geological activity that preceded human records, using the records of increased carbon dioxide found in the tree rings. The Smell Mudpots are acidic features with a limited water supply. Some microorganisms use hydrogen sulfide, which rises from deep within the earth, as an energy source. They help convert the gas to sulfuric acid, which breaks down rock to wet clay mud and creates the area’s smell. The pungent odor of rotten eggs is caused by the hydrogen sulfide gas. Various gases escape through the wet clay mud, causing it to bubble. Mudpot consistency and activity vary with the seasons and precipitation. Mud Volcano Area The Mud Volcano area has many mudpots and hillsides strewn with trees cooked by steam. The hydrothermal features here are some of the most acidic in the park. Mud Volcano is near the greatest uplift and sinking of the Yellowstone Caldera floor. Many faults converge here and earthquakes are common. The areas surrounding the Mud Volcano vent and the other major vent near Old Faithful are called resurgent domes. Resurgent domes are active ground deformation, where the land moves up or down with the fluctuation of the magma chamber below. Scientists monitor these domes closely for information about ongoing volcanic activity. Use Caution in Hydrothermal Areas Stay on boardwalks and designated trails. Hydrothermal water can severely burn you. Never run, push, or shove. Supervise children at all times. Do not scratch hydrothermal mats. You are responsible for your safety. Think safety, act safely. Yellowstone is a dangerous place.