U.S. Geological Survey Photographic Library
ID. Jackson, W.H. 95
Yellowstone National Park, Wyoming. Mud Springs at Crater Hills near Sulphur Spring. The contents of this spring are a fine, siliceous, pearl-colored mud, the consistency of thick, hasty pudding. The surface is covered with puffs of mud, which, as they burst, give off a thud-like noise, and then the paint-like liquid recedes from the center of the puffs in a perfect series of rings to the side. The explosion is produced by the escape of sulfurated hydrogen gas through the mud. 1871.U.S. Geological and Geographical Survey of the Territories (Hayden Survey).
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