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Sawmill Geyser, Upper Geyser Basin, Yellowstone National Park, Wyoming, USA.
Yellowstone National Park is known for its variety of wildlife and - even more - for its many geothermal features like geysers, fumaroles, hot springs etc., the best known of them being the geyser "Old Faithful". Yellowstone National Park is said to be the first National Park of the World. It is inscribed in the World Heritage List of the UNESCO.
---quotation from whc.unesco.org:---
Yellowstone National Park, established in 1872, covers 9,000 km2 of a vast natural forest of the southern Rocky Mountains in the North American west. It boasts an impressive array of geothermal phenomena, with more than 3,000 geysers, lava formations, fumaroles, hot springs and waterfalls, lakes and canyons. It is equally known for its wildlife: grizzly bears, bison, wolves and wapiti, North American elk.
The park is part of the most seismically active region of the Rocky Mountains, a volcanic 'hot spot'. The Yellowstone Plateau, now a forested area of 650,000 ha with an average elevation of 2,000 m, was formed out of the accumulation of rhyolite magma. The plateau is flanked on the north, east and south by mountains that rise to 4,000 m. Crustal uplifts 65 million years ago raised blocks of crust to form the southern Rocky Mountains. After that, volcanic outflows of andesitic composition were common to about 40 million years ago. Andesitic ashflows and mudflows of the Eocene age covered forests, which became petrified. Some 200 species of petrified plant have been found. A more recent period of rhyolitic volcanism began in the region about 2 million years ago, during which time thousands of cubic kilometres of rhyolitic magma filled immense chambers under the plateau and then erupted to the surface. Three cycles of eruption produced huge explosive outbursts of ash. The latest eruptive cycle formed a caldera 45 km wide and 75 km long, when the active magma chambers erupted and collapsed. The crystallizing magma is the source of heat for hydrothermal features such as geysers, hot springs, mud pots and fumaroles.
Yellowstone contains 200-250 active geysers and perhaps 10,000 thermal features. Most of the area was glaciated during the Pleistocene and many glacial features remain. The park lies at the headwaters of three major rivers. Yellowstone River is a major tributary of the Missouri River that flows via the Mississippi to the Gulf of Mexico. Firehole and Gibbon rivers unite to form the Madison, which also joins the Missouri. Snake River arises near the park's south boundary and joins the Columbia to flow into the Pacific. Yellowstone Lake is the largest lake at high elevation (2,357 m) in North America. Lower Yellowstone Falls is the highest of more than 40 named waterfalls in the park.
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USA tour September 2006
Artists Paintpots, Yellowstone National Park, Wyoming, USA.
Yellowstone National Park is known for its variety of wildlife and - even more - for its many geothermal features like geysers, fumaroles, hot springs etc., the best known of them being the geyser "Old Faithful". Yellowstone National Park is said to be the first National Park of the World. It is inscribed in the World Heritage List of the UNESCO.
---quotation from whc.unesco.org:---
Yellowstone National Park, established in 1872, covers 9,000 km2 of a vast natural forest of the southern Rocky Mountains in the North American west. It boasts an impressive array of geothermal phenomena, with more than 3,000 geysers, lava formations, fumaroles, hot springs and waterfalls, lakes and canyons. It is equally known for its wildlife: grizzly bears, bison, wolves and wapiti, North American elk.
The park is part of the most seismically active region of the Rocky Mountains, a volcanic 'hot spot'. The Yellowstone Plateau, now a forested area of 650,000 ha with an average elevation of 2,000 m, was formed out of the accumulation of rhyolite magma. The plateau is flanked on the north, east and south by mountains that rise to 4,000 m. Crustal uplifts 65 million years ago raised blocks of crust to form the southern Rocky Mountains. After that, volcanic outflows of andesitic composition were common to about 40 million years ago. Andesitic ashflows and mudflows of the Eocene age covered forests, which became petrified. Some 200 species of petrified plant have been found. A more recent period of rhyolitic volcanism began in the region about 2 million years ago, during which time thousands of cubic kilometres of rhyolitic magma filled immense chambers under the plateau and then erupted to the surface. Three cycles of eruption produced huge explosive outbursts of ash. The latest eruptive cycle formed a caldera 45 km wide and 75 km long, when the active magma chambers erupted and collapsed. The crystallizing magma is the source of heat for hydrothermal features such as geysers, hot springs, mud pots and fumaroles.
Yellowstone contains 200-250 active geysers and perhaps 10,000 thermal features. Most of the area was glaciated during the Pleistocene and many glacial features remain. The park lies at the headwaters of three major rivers. Yellowstone River is a major tributary of the Missouri River that flows via the Mississippi to the Gulf of Mexico. Firehole and Gibbon rivers unite to form the Madison, which also joins the Missouri. Snake River arises near the park's south boundary and joins the Columbia to flow into the Pacific. Yellowstone Lake is the largest lake at high elevation (2,357 m) in North America. Lower Yellowstone Falls is the highest of more than 40 named waterfalls in the park.
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USA tour September 2006
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Top of Sicily with 3323 m, largest volcano in Europe and one of most active in the world, Etna is full of superlatives !
Nestled along the Reykjanes Peninsula, Krýsuvík is a striking geothermal field where the Earth hisses, bubbles, and steams. Surrounded by colorful rhyolite hills, the area features boiling mud pots, steaming fumaroles, and sulfur-stained terrain. It's part of the Mid-Atlantic Ridge, where tectonic plates drift apart. Wooden boardwalks allow visitors to walk safely through this active landscape. The area is also home to nearby Kleifarvatn Lake
Turrialba Volcano is named after the region of Costa Rica in which the volcano is situated in Turrialba County, Cartago of Costa Rica. The stratovolcano is 3,340 m (10,958 ft) high and is about 45 minutes from the Atlantic slope town of Turrialba. The summit has three craters, one of which has fumaroles and sulfur pits.
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
A popular fumarole field on the cast flank of Tangkuban Perahu Volcano (and geothermal concession), West Java, Indonesia. Taken by Joe LaFleur, Geologist Extraordinaire, while doing field exploration for Raser GeothermaL Taken in December 2010.
Turrialba Volcano is named after the region of Costa Rica in which the volcano is situated in Turrialba County, Cartago of Costa Rica. The stratovolcano is 3,340 m (10,958 ft) high and is about 45 minutes from the Atlantic slope town of Turrialba. The summit has three craters, one of which has fumaroles and sulfur pits.
A capture by mobile phone.
Mud Volcano area
The Mud Volcano thermal area is an area of muddy hot springs and fumaroles located near one of the Yellowstone Volcano’s vents. Its 5.9 miles north of Fishing Bridge Junction. The Mud Cauldron is viewable from the pathway right in front of the parking area. It is a large area of mud and water heated by steam escaping from far below.
Geo-chemistry of mud volcano
Hydrogen sulfide gas rising from Yellowstone’s magma chamber causes the rotten-egg smell. Microorganisms, or thermophiles, use this gas as a source of energy, and then help turn the gas into sulfuric acid. The acid then breaks down the rocks and soil into mud. Many of the colors seen are vast communities of thermophiles, but some of the yellow is pure sulphur. When iron mixes with sulphur to form iron sulfide, gray and black swirls sometimes appear in the mud (From description of the display board in the park).
My experience
We entered Yellowstone NP through the eastern entrance using U.S. Route 14. It had been a moderate snow fall in the end of the first week of October, 2017. From few kilometers before reaching Yellowstone Lake, remnants of devastating wild fire were being evident. It was a shocking sight for me at the beginning and could not perceive how fire had devastated hundreds of acres of alpine forests in the valleys and atop the hills. But when I had a closer look to the floor of the forests, I was amazed by the facts how nature maintains its ecological balance! Numerous tiny siblings are growing besides the burnt and decaying logs. The future forests of the park are coming alive.
The park seemed to me the world’s finest natural laboratory and archive to study and understand all the faculties of human intellect.
The qualities of the photographs are not satisfactory, because they were taken so fast through the glass windows of our running bus. But I didn’t want to miss such life time opportunities. The overall beauties were essentially more important than technicalities, as I always believe.
Our luck didn’t favor anyway in this park trip, when our tour guide had declared a forecast for heavy snowfall next day since morning. He therefore decided to visit as many spots as possible in a single day, and not to wait for day-2. I hurried through the trails taking as many snaps as possible.
The next day heavy snowfall started since 9 am, and our guide cancelled the day-2 trip. Thanks God…we covered somehow all the spots on the first day.
I hope, you may like my Yellowstone series…
Description
Yellowstone National Park is an American national park located in Wyoming, Montana, and Idaho. Approximately 96 percent of the land area of Yellowstone National Park is located within the state of Wyoming. The Park spans an area of 8,983 km2 comprising lakes, canyons, rivers and mountain ranges. The park is known for its wildlife and its many geothermal features. It has many types of ecosystems, but the subalpine forest is the most abundant. It is part of the South Central Rockies forests eco-region.
It was established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone was the first national park in the U.S. and is also widely held to be the first national park in the world. Native Americans have lived in the Yellowstone region for at least 11,000 years. Aside from visits by mountain -men during the early to mid-19th century, organized exploration did not begin until the late 1860s.
The park contains the headwaters of the Yellowstone River, from which it takes its historical name. Although it is commonly believed that the river was named for the yellow rocks seen in the ‘Grand Canyon of the Yellowstone’, the Native American name source is unclear.
Yellowstone Lake is one of the largest high-elevation lakes in North America and is centered over the Yellowstone Caldera, the largest supervolcano on the continent. The caldera is considered as an active volcano. It has erupted with tremendous force several times in the last two million year. The Yellowstone Caldera is the largest volcanic system in North America. It has been termed a "supervolcano" because the caldera was formed by exceptionally large explosive eruptions. The magma chamber that lies under Yellowstone is estimated to be a single connected chamber, about 60 km long, 29 km wide, and 5 to 12 km deep. Yellowstone Lake is up to 400 feet deep and has 180 km of shoreline.The lake is at an elevation of 7,733 feet above sea levels. Half of the world's geysers and hydrothermal features are there in Yellowstone, fueled by this ongoing volcanism. Lava and rocks from volcanic eruptions cover most of the land area of Yellowstone. The park is the centerpiece of the Greater Yellowstone Ecosystem, the largest remaining nearly-intact ecosystem in the Earth's northern temperate zone. In 1978, Yellowstone was named a UNESCO World Heritage Site.
In May 2001, the U.S. Geological Survey, Yellowstone National Park, and the University of Utah created the Yellowstone Volcano Observatory (YVO), a partnership for long-term monitoring of the geological processes of the Yellowstone Plateau volcanic field, for disseminating information concerning the potential hazards of this geologically active region.
Hundreds of species of mammals, birds, fish, and reptiles have been documented, including several that are either endangered or threatened. The vast forests and grasslands also include unique species of plants.Yellowstone Park is the largest and most famous megafauna location in the contiguous United States. Grizzly bears, wolves, and free-ranging herds of bison and elk live in this park. The Yellowstone Park bison herd is the oldest and largest public bison herd in the United States.
Forest fires occur in the park each year. In the largest forest fires of 1988, nearly one third of the park was burnt.
Yellowstone has numerous recreational opportunities, including hiking, camping, boating, fishing and sightseeing. Paved roads provide close access to the major geothermal areas as well as some of the lakes and waterfalls. During the winter, visitors often access the park by way of guided tours that use either snow coaches or snowmobiles.
Fire in Yellowstone NP
Causes of wildfire in Yellowstone NP
Wildfire has had a role in the dynamics of Yellowstone’s ecosystems for thousands of years. Although many fires were caused by human activities, most ignitions were natural. The term "natural ignition" usually refers to a lightning strike. Afternoon thunderstorms occur frequently in the northern Rocky Mountains but release little precipitation, a condition known as ‘dry lightning’. In a typical season there are thousands of lightning strikes in Yellowstone. Lightning strikes are powerful enough to rip strips of bark off of a tree in a shower of sparks and blow the pieces up to 100 feet away. However, most lightning strikes do not result in a wildfire because fuels are not in a combustible state.
The great fire incidence of 1988
The Yellowstone fires of 1988 collectively formed the largest wildfire in the recorded history of Yellowstone National Park in the United States. Starting as many smaller individual fires, the flames quickly spread out of control due to drought conditions and increasing winds, combining into one large conflagration which burned for several months. The fires almost destroyed two major visitor destinations and, on September 8, 1988, the entire park closed to all non-emergency personnel for the first time in its history. Only the arrival of cool and moist weather in the late autumn brought the fires to an end. A total of 793,880 acres, or 36 percent of the park was affected by the wildfires.
Fire incidence, 2016
As of September 21, 2016, 22 fires (human and lightning-caused) have burned more than 62,000 acres in Yellowstone National Park, making it the highest number of acres burned since the historic 1988 fire.
Heritage and Research Center
The Heritage and Research Center is located at Gardiner, Montana, near the north entrance to the park. The center is home to the Yellowstone National Park's museum collection, archives, research library, historian, archeology lab, and herbarium. The Yellowstone National Park Archives maintain collections of historical records of Yellowstone and the National Park Service. The collection includes the administrative records of Yellowstone, as well as resource management records, records from major projects, and donated manuscripts and personal papers. The archives are affiliated with the National Archives and Records Administration.
A Quick Overview Map of Yellowstone
(www.yellowstonepark.com/park/overview-map-yellowstone)
Free Yellowstone Trip Planner:
( www.yellowstonepark.com/travel-guides/yellowstone-trip-pl...)
8 Best Yellowstone Geyser Basins and Map
( www.yellowstonepark.com/things-to-do/yellowstone-geyser-b... )
National Park Maps
( www.yellowstonepark.com/park/national-park-maps )
Interactive map of ALL Yellowstone thermal features at the Yellowstone Research Coordination Network
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
These steam plumes are part of Brady's Hot Springs, a hydrothermal area along the Brady Fault in northwestern Nevada. Geothermal energy generation in the area has occurred for many years and the surface hot springs have long been wrecked. The steam plumes ("fumaroles") are not natural - the original hot springs had flowing hot water at the surface, with active siliceous sinter deposition. The current water table is well below the surface. It dropped due to geothermal power development.
People need to understand that geothermal power is NOT GREEN. Brady's Hot Springs have been ruined forever - might as well continue making electricity there. Untapped "hydrothermal resources" need to be left as is. Such environments are among the rarest and most beautiful on Earth (for example, Yellowstone). Geothermal drilling destroys the environment. Overpopulated hominids cannot continue wrecking the Earth's surface environment ad infinitum.
Nikon D40
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2009/09/27 10:49:22.6
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Tel.: (56) 22758 7209
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
Mud Volcano Area, Yellowstone National Park, Wyoming, USA.
Yellowstone National Park is known for its variety of wildlife and - even more - for its many geothermal features like geysers, fumaroles, hot springs etc., the best known of them being the geyser "Old Faithful". Yellowstone National Park is said to be the first National Park of the World. It is inscribed in the World Heritage List of the UNESCO.
---quotation from whc.unesco.org:---
Yellowstone National Park, established in 1872, covers 9,000 km2 of a vast natural forest of the southern Rocky Mountains in the North American west. It boasts an impressive array of geothermal phenomena, with more than 3,000 geysers, lava formations, fumaroles, hot springs and waterfalls, lakes and canyons. It is equally known for its wildlife: grizzly bears, bison, wolves and wapiti, North American elk.
The park is part of the most seismically active region of the Rocky Mountains, a volcanic 'hot spot'. The Yellowstone Plateau, now a forested area of 650,000 ha with an average elevation of 2,000 m, was formed out of the accumulation of rhyolite magma. The plateau is flanked on the north, east and south by mountains that rise to 4,000 m. Crustal uplifts 65 million years ago raised blocks of crust to form the southern Rocky Mountains. After that, volcanic outflows of andesitic composition were common to about 40 million years ago. Andesitic ashflows and mudflows of the Eocene age covered forests, which became petrified. Some 200 species of petrified plant have been found. A more recent period of rhyolitic volcanism began in the region about 2 million years ago, during which time thousands of cubic kilometres of rhyolitic magma filled immense chambers under the plateau and then erupted to the surface. Three cycles of eruption produced huge explosive outbursts of ash. The latest eruptive cycle formed a caldera 45 km wide and 75 km long, when the active magma chambers erupted and collapsed. The crystallizing magma is the source of heat for hydrothermal features such as geysers, hot springs, mud pots and fumaroles.
Yellowstone contains 200-250 active geysers and perhaps 10,000 thermal features. Most of the area was glaciated during the Pleistocene and many glacial features remain. The park lies at the headwaters of three major rivers. Yellowstone River is a major tributary of the Missouri River that flows via the Mississippi to the Gulf of Mexico. Firehole and Gibbon rivers unite to form the Madison, which also joins the Missouri. Snake River arises near the park's south boundary and joins the Columbia to flow into the Pacific. Yellowstone Lake is the largest lake at high elevation (2,357 m) in North America. Lower Yellowstone Falls is the highest of more than 40 named waterfalls in the park.
---end of quotation---
USA tour September 2006
This area at Lassen Volcanic National Park is called Sulphur Works due to the sulfurous gases, including hydrogen sulfide (smelling like rotten eggs) and sulfur dioxide, emitted by fumaroles that are found there.
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
Namafjall Hverir (Námafjall Hverir), Iceland - Walking around Namafjall is like being on mars. It's a dramatic change in the landscape, creating a small area with a stark red landscape covered with fumaroles and mud pots. Being a high temperature geothermal area, temperatures can get over 200C 1000 meters down. The fumaroles emit steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide.
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
The fumarole field at Asahidake, an area of thermal springs and gas vents where magma or hot igneous rocks at shallow depth are releasing gases or interacting with groundwater.
Asahidake, a stratovolcano, is the tallest mountain in Hokkaidō, Japan. Part of the Daisetsuzan Volcanic Group of the Ishikari Mountains, it is located in the northern part of the Daisetsuzan National Park.
The geothermal areas of Yellowstone include several geyser basins in Yellowstone National Park as well as other geothermal features such as hot springs, mud pots, and fumaroles. The number of thermal features in Yellowstone is estimated at 10,000. A study that was completed in 2011 found that a total of 1,283 geysers have erupted in Yellowstone, 465 of which are active during an average year. These are distributed among nine geyser basins, with a few geysers found in smaller thermal areas throughout the Park. The number of geysers in each geyser basin are as follows: Upper Geyser Basin (410), Midway Geyser Basin (59), Lower Geyser Basin (283), Norris Geyser Basin (193), West Thumb Geyser Basin (84), Gibbon Geyser Basin (24), Lone Star Geyser Basin (21), Shoshone Geyser Basin (107), Heart Lake Geyser Basin (69), other areas (33). Although famous large geysers like Old Faithful are part of the total, most of Yellowstone's geysers are small, erupting to only a foot or two. The hydrothermal system that supplies the geysers with hot water sits within an ancient active caldera. Many of the thermal features in Yellowstone build up sinter, geyserite, or travertine deposits around and within them.
The various geyser basins are located where rainwater and snowmelt can percolate into the ground, get indirectly superheated by the underlying Yellowstone hotspot, and then erupt at the surface as geysers, hot springs, and fumaroles. Thus flat-bottomed valleys between ancient lava flows and glacial moraines are where most of the large geothermal areas are located. Smaller geothermal areas can be found where fault lines reach the surface, in places along the circular fracture zone around the caldera, and at the base of slopes that collect excess groundwater. Due to the Yellowstone Plateau's high elevation the average boiling temperature at Yellowstone's geyser basins is 199 °F (93 °C). When properly confined and close to the surface it can periodically release some of the built-up pressure in eruptions of hot water and steam that can reach up to 390 feet (120 m) into the air (see Steamboat Geyser, the world's tallest geyser). Water erupting from Yellowstone's geysers is superheated above that boiling point to an average of 204 °F (95.5 °C) as it leaves the vent. The water cools significantly while airborne and is no longer scalding hot by the time it strikes the ground, nearby boardwalks, or even spectators. Because of the high temperatures of the water in the features it is important that spectators remain on the boardwalks and designated trails. Several deaths have occurred in the park as a result of falls into hot springs.
Prehistoric Native American artifacts have been found at Mammoth Hot Springs and other geothermal areas in Yellowstone. Some accounts state that the early people used hot water from the geothermal features for bathing and cooking. In the 19th century Father Pierre-Jean De Smet reported that natives he interviewed thought that geyser eruptions were "the result of combat between the infernal spirits". The Lewis and Clark Expedition traveled north of the Yellowstone area in 1806. Local natives that they came upon seldom dared to enter what we now know is the caldera because of frequent loud noises that sounded like thunder and the belief that the spirits that possessed the area did not like human intrusion into their realm. The first white man known to travel into the caldera and see the geothermal features was John Colter, who had left the Lewis and Clark Expedition. He described what he saw as "hot spring brimstone". Beaver trapper Joseph Meek recounted in 1830 that the steam rising from the various geyser basins reminded him of smoke coming from industrial smokestacks on a cold winter morning in Pittsburgh, Pennsylvania. In the 1850s famed trapper Jim Bridger called it "the place where Hell bubbled up"
The heat that drives geothermal activity in the Yellowstone area comes from brine (salty water) that is 1.5–3 miles (7,900–15,800 ft; 2,400–4,800 m) below the surface. This is actually below the solid volcanic rock and sediment that extends to a depth of 3,000 to 6,000 feet (900 to 1,800 m) and is inside the hot but mostly solid part of the pluton that contains Yellowstone's magma chamber. At that depth the brine is superheated to temperatures that exceed 400 °F (204 °C) but is able to remain a liquid because it is under great pressure (like a huge pressure cooker).
Convection of the churning brine and conduction from surrounding rock transfers heat to an overlaying layer of fresh groundwater. Movement of the two liquids is facilitated by the highly fractured and porous nature of the rocks under the Yellowstone Plateau. Some silica is dissolved from the fractured rhyolite into the hot water as it travels through the fractured rock. Part of this hard mineral is later redeposited on the walls of the cracks and fissures to make a nearly pressure-tight system. Silica precipitates at the surface to form either geyserite or sinter, creating the massive geyser cones, the scalloped edges of hot springs, and the seemingly barren landscape of geyser basins.
There are at least five types of geothermal features found at Yellowstone:
Fumaroles: Fumaroles, or steam vents, are the hottest hydrothermal features in the park. They have so little water that it all flashes into steam before reaching the surface. At places like Roaring Mountain, the result is loud hissing of steam and gases.
Geysers: Geysers such as Old Faithful are a type of geothermal feature that periodically erupt scalding hot water. Increased pressure exerted by the enormous weight of the overlying rock and water prevents deeper water from boiling. As the hot water rises it is under less pressure and steam bubbles form. They, in turn, expand on their ascent until the bubbles are too big and numerous to pass freely through constrictions. At a critical point the confined bubbles actually lift the water above, causing the geyser to splash or overflow. This decreases the pressure of the system and violent boiling results. Large quantities of water flash into tremendous amounts of steam that force a jet of water out of the vent: an eruption begins. Water (and heat) is expelled faster than the geyser's recharge rate, gradually decreasing the system's pressure and eventually ending the eruption.
Hot springs: Hot springs such as Grand Prismatic Spring are the most common hydrothermal features in the park. Their plumbing has no constrictions. Superheated water cools as it reaches the surface, sinks, and is replaced by hotter water from below. This circulation, called convection, prevents water from reaching the temperature needed to set off an eruption. Many hot springs give rise to streams of heated water.
Mudpots: Mudpots such as Fountain Paint Pots are acidic hot springs with a limited water supply. Some microorganisms use hydrogen sulfide (rotten egg smell), which rises from deep within the earth, as an energy source. They convert the gas into sulfuric acid, which breaks down rock into clay.
Travertine terraces: Travertine terraces, found at Mammoth
Hot Springs, are formed from limestone (a rock type made of calcium carbonate). Thermal waters rise through the limestone, carrying high amounts of dissolved carbonate. Carbon dioxide is released at the surface and calcium carbonate deposited as travertine, the chalky white rock of the terraces. These features constantly and quickly change due to the rapid rate of deposition.
The areas arround hot springs are usually very colorful. This was taken yesterday in Seltún, a few minutes south of Kleifarvatn in SW Iceland. The different colors and textures are caused by sulphur and other minerals that are deposited from the bubbling mud pots and steaming fumaroles that abound there.
Sulfur crystals on a fumarole vent of Nisyros Volcano, Greece. The Sulfur is probably formed from a redox reaction involving hydrogen sulfide and sulfur dioxide, both produced from magmatic activity, and in the presence of moisture. Water is the other product (most of it as steam).
Southern high-temperature fumarole on the summit of the dome of La Soufriere, Basse Terre, Guadeloupe.
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide. However, there are some Mud Volcanoes and Mud Geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.