Lobby > Exhibits > Hot Water Treasures > Types of Thermal Features > Mudpots

WHAT IS A MUDPOT?

Mudpot Colors Seasonal Variations

A mud pot is a natural double boiler! Surface water collects in a shallow, impermeable (usually due to a lining of clay) depression that has no direct connection to an underground water flow. Thermal water beneath the depression causes steam to rise through the ground, heating the collected surface water.

Hydrogen sulfide gas is usually present, giving mud pots their characteristic odor of rotten eggs. Some microorganisms use the hydrogen sulfide for energy. The microbes help convert the gas to sulfuric acid, which breaks down rock into clay. The result is a gooey mix through which gases gurgle and bubble.

After coming upon Mud Volcano during his 1871 expedition to Yellowstone, Ferdinand Hayden described the mudpot as "the greatest marvel we have met with."

Next: Mudpot Colors