Travel Reference
In-Depth Information
Canada geese. There are popular viewing areas 1 mile north of Sulfur Cauldron and 1.5
miles north of Trout Creek, where rangers lead wildlife watching trips four times a week
at 7am. Set up your spotting scope early, as the pullouts fill with cars an hour or two be-
fore dusk.
MUD VOLCANO
One of the park's most geologically volatile regions, this thermal area 10 miles south of
Canyon Junction and 6 miles north of Fishing Bridge Junction contains an assortment of
mud pots and other gurgling sulfurous pits. The nearby Sour Creek resurgent dome is the
fuel that superheats the mud volcanoes, while the high acidity breaks down rock into mud
pots rather than creating the pressurized geyser plumbing more characteristic of alkaline
thermal features. During a series of earthquakes in 1979 the mud pots developed enough
heat and gases to literally cook lodgepole pines and grasses on neighboring hillsides. One
mud pot recently emerged from underneath the parking lot.
Mud Volcano itself has not erupted since the 1871 Langford-Washington-Doane ex-
pedition first encountered it. A crater is all that remains of the original cone. Dragon's
Mouth Spring gets its name from the deep thumping and crashing that emanates from a
hidden lair that looks like it guards the gateway to the underworld. In 1999 the pool
cooled and its color changed from green to white and now gray.
The easiest way to see the other sights is to follow the 2.3-mile loop boardwalk (there
are some steps) clockwise, past Mud Geyser and up Cooking Hillside. Halfway up,
Churning Cauldron is a favorite; waves of water have created tiny beaches here. The
dark colors of this and other pots are due to the presence of iron sulfides.
Black Dragon's Cauldron appeared in 1948 in a crack in the earth and has since
moved south 200ft along the crack to produce an elliptical pool. The rolling motion of the
water is actually due to rising gases rather than boiling water. Nearby Sour Lake looks
like a nice place for a swim but its waters are as acidic as battery acid. Further downhill,
Grizzly Fumarole changes throughout the year from a fumarole to a mud pot and even a
muddy spring, according to the amount of moisture in the ground.
Sulfur Cauldron , just a few hundred yards north, by a pullout in the road, is one of the
most acidic springs in the park, at pH 1.3. Other thermal areas, visible across the Yellow-
stone River, can only be reached by hiking the Howard Eaton Trail from Fishing Bridge.
Rangers lead two-hour walks around the site at 4pm, but sadly no longer go to the
Gumper , a huge seething mud pot behind Sour Lake and off-limits to visitors.
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