A mudpot, or mud pool, is a type of acidic

hot spring A hot spring, hydrothermal spring, or geothermal spring is a Spring (hydrology), spring produced by the emergence of Geothermal activity, geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow ...

, or fumarole, with limited water. It usually takes the form of a pool of bubbling

mud Mud (, or Middle Dutch) is loam, silt or clay mixed with water. Mud is usually formed after rainfall or near water sources. Ancient mud deposits hardened over geological time to form sedimentary rock such as shale or mudstone (generally cal ...

, as a result of the acid and microorganisms decomposing surrounding rock into clay and mud.

Description

The mud of a mudpot takes the form of a

viscous Viscosity is a measure of a fluid's rate-dependent resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup h ...

, often bubbling,

slurry A slurry is a mixture of denser solids suspended in liquid, usually water. The most common use of slurry is as a means of transporting solids or separating minerals, the liquid being a carrier that is pumped on a device such as a centrifugal pu ...

. As the boiling mud is often squirted over the brims of the mudpot, a form resembling a mini-volcano of mud starts to build up, sometimes reaching heights of . Although mudpots are often called "mud volcanoes", true

mud volcano A mud volcano or mud dome is a landform created by the eruption of mud or Slurry, slurries, water and gases. Several geological processes may cause the formation of mud volcanoes. Mud volcanoes are not true Igneous rock, igneous volcanoes as th ...

es are very different in nature. The mud of a mudpot is generally of white to greyish color, but is sometimes stained with reddish or pink spots from

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

compounds. When the slurry is particularly colorful, the feature may be referred to as a paint pot.

Geology

Mudpots form in high-temperature geothermal areas where water supply is short. The little water that is available rises to the surface at a spot where the soil is rich in

volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

ash,

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

, and other fine particulates. The thickness of the mud usually changes along with seasonal changes in the

water table The water table is the upper surface of the phreatic zone or zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the loc ...

Notable sites

The

geothermal areas of Yellowstone The geothermal areas of Yellowstone include several geyser basins in Yellowstone National Park as well as other Geothermal activity, geothermal features such as hot springs, mud pots, and fumaroles. The number of thermal features in Yellowstone ...

National Park contain several notable examples of both mudpots and paint pots, as do some areas of

Azerbaijan Azerbaijan, officially the Republic of Azerbaijan, is a Boundaries between the continents, transcontinental and landlocked country at the boundary of West Asia and Eastern Europe. It is a part of the South Caucasus region and is bounded by ...

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

and

Nicaragua Nicaragua, officially the Republic of Nicaragua, is the geographically largest Sovereign state, country in Central America, comprising . With a population of 7,142,529 as of 2024, it is the third-most populous country in Central America aft ...

. Several locations in and around the

Salton Sea The Salton Sea is a shallow, landlocked, highly salinity, saline endorheic lake in Riverside County, California, Riverside and Imperial County, California, Imperial counties in Southern California. It lies on the San Andreas Fault within the S ...

in California are also home to active mudpots, including the moving Niland Geyser. In the case of Niland Geyser, its name is somewhat of a misnomer, as the release of

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

by seismic activity from the nearby

San Andreas Fault The San Andreas Fault is a continental Fault (geology)#Strike-slip faults, right-lateral strike-slip transform fault that extends roughly through the U.S. state of California. It forms part of the tectonics, tectonic boundary between the Paci ...

is responsible for its behaviour, rather than through geothermal activity. The fluid contained within it is near ambient atmospheric temperature, rather than boiling, measuring around .

Photo gallery

File:Mudpot west thumb 20190717 135010 VID.webm, A large boiling mudpot in the parking area of West Thumb Geyser Basin in

Yellowstone Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...

Image:Fountain Paint Pots in Yellowstone-750px.JPG, Fountain Paint Pots,

Yellowstone National Park Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...

Image:MudPot_8334.jpg, Mudpot in Bumpass Hell,

Lassen Volcanic National Park Lassen Volcanic National Park is a List of national parks of the United States, national park of the United States in northeastern California. The dominant feature of the park is Lassen Peak, the largest lava dome, plug dome volcano in the wo ...

Image:Yellowstone mud pot p1090998.jpg, Mudpot in Yellowstone National Park Image:RincónMudpot Apr2003.jpg, Mudpot at Rincón de la Vieja Volcano National Park,

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

Image:Mud pool near Waiotapu.ogg, Short video of mud pool activity near Waiotapu,

File:Mud pool in Solfatara crater.jpg, The surface of a boiling mudpot in the crater of Solfatara, part of the

Campi Flegrei The Phlegraean Fields (, ; ) is a large volcanic caldera west of Naples, Italy. The Neapolitan Yellow Tuff eruption (about 12ka BP) produced just 50 cubic kilometers. It is, however, one of relatively few volcanoes large enough to form a cal ...

complex,

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

File:Mud pool at Orakei Korako.ogv, Video of mud pool at Orakei Korako,

Image:Hverir mudpool 2012-06-05.jpg, Erupting mudpot at Hverir, Iceland Image:YellowstoneMudpit.jpg, A mud pot in

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

References

External links

{{Commons category, Mudpots
Mudpots at Yellowstone National Park official site

Springs (hydrology) Volcanic landforms Volcanism Geothermal areas Articles containing video clips Volcanic degassing