As with the other hydrothermal features of Yellowstone,
the mudpots are the result of a unique combination of ground
water, magma, and subsurface cracks. These components combine
to form the various pools of bubbling mud and sometimes
explosive cones called mud volcanoes.
Ground water comes from infiltrating rain and snowmelt. Some
areas have more ground water than others. This area is on the side
of a hillside, so ground water is more limited than in valleys
where geysers and hot springs are located. What water that does
come to the surface doesn’t flow out of the pools quickly and is
often recirculated.
The heat comes from the cooling magma which is between 3 and 8
miles below the surface. For magma, this is very close to the
surface. Hydrogen sulfide, a gas that smells like rotten eggs, is
common in cooling magma. Specialized microorganisms “feed” on this
gas converting it into sulfuric acid. This acid decomposes the
bedrock into clay.
Fissures, or cracks in the ground, allow the ground water to
move the clay up to the surface where it forms pools. There is not
enough water to wash away the clay and acid, so it remains in the
pools. Where there is more ground water, the pools are more liquidy
and where there is little ground water, the pools look like a very
thick putty. The character of a mud pot will vary by season due to
the availability of ground water in each season.
There are even some places where this is almost no ground water.
At these cracks, ground water is boiled away faster than it comes.
Other gasses such as hydrogen sulfide and carbon dioxide flow out
as well. This formation is called a fumarole.
Many of the pools bubble furiously, however none are boiling.
Carbon dioxide, hydrogen sulfide and other gasses are constantly
coming out of solution (like a carbonated drink) creating these
bubbles.
Logging requirements:
Send me a note with :
- The text "GC15A0Q Mud Volcanoes and Mud Pots" on the first
line
- The number of people in your group.
- Send me a note with the coordinates and name given to one of
each of the following features this basin
- a mud pot
- a mud volcano
- a fumarole
- At Churning Cauldron (the given coordinates), find out how the
temperature has changed over time
- At the secondary coordinates (N44 37.679 W110 26.004), what is
the name of this feature and what is unique about it (a specific
number is needed for this one); what do you think this indicates
about the amount of ground water in this area.
The above information was compiled from the
following sources:
- NPS informational Pannel
- Fritz, William J., Roadside Geology of the
Yellowstone Country, Mountain Press Publishing Company, May
1989.
- Mud Volcano Trail Guide including Sulphur
Caldron, Yellowstone National Park, Yellowstone Association, April
2007
- The Geologic Story of Yellowstone National
Park, William R. Keefer Illustrated by John R. Stacy, GEOLOGICAL
SURVEY BULLETIN 1347 1975 .
Placement approved by the
Yellowstone National Park