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Norris Geyser Basin

The Dye family on the boardwalk at Norris Geyser Basin.

Norris Geyser Basin is one of the hottest and most dynamic of Yellowstone's hydrothermal areas. It is divided into two parts: Porcelain Basin and Back Basin. Steamboat Geyser is the tallest active geyser in the world. There are lots of other geysers and hot springs.

Interactive Map

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Waypoints

Waypoint Latitude Longitude Description
Bookstore -110.70332192287 44.72605850222471  
Museum -110.7035373277481 44.72650470525068  
Porcelain Basin Overlook -110.7034118432748 44.72687703129478 Rainbow colors, hissing steam, and pungent odors greet your senses in Porcelain Basin. This basin pulsates from steam and boiling water beneath the surface. Its features appear and disappear often, but some hot springs and geysers have become relatively stable features. Take it all in from Porcelain Basin Overlook. You might see a small geyser splashing, sometimes two or three, sometimes none. Notice the milky blue pools—they are saturated with silica, which is the primary component of glass. Norris's thermal waters contain the highest concentration of silica in Yellowstone. Some of the orange color results from minerals containing elements such as iron and arsenic. Thermophiles also create colors you see, such as orange, greenish-black, and emerald green.
Black Growler Steam Vent -110.7034894121936 44.72736596189597 As you descend into Porcelain Basin, you'll pass Black Growler Steam Vent, a steady column of steam. A strong steam vent has been in different locations on this hill for many years, and it has always been called Black Growler. No one knows why it disappears and reappears, but Black Growler always roars back.
Thermophiles -110.7031733885537 44.72846494268023 The boardwalk across Porcelain Basin takes you over hot, acidic waters. It also provides a place to observe thermophile communities such as the streamers and mats populated by Zygogonium, an alga dark on the surface but bright green beneath. It thrives in water of pH 2-3 and temperatures of 68-96°F. Also look for the movement of ephydrid flies and other insects feeding off thermophile communities.
Constant Geyser -110.7030108415326 44.72861202229724 Constant Geyser could catch you by surprise. Its eruptions burst 20-30 feet high but last barely ten seconds. One or more erupt ions may occur within a few minutes of each other; the geyser may be quiet for 20 minutes or several hours.
Whirligig Geyser -110.7031564799766 44.72869011836529 When Whirligig Geyser erupts, its pulsing sound often can be heard around the basin. Its rust-orange color comes from iron that has been oxidized, in part, by thermophiles.
Pinwheel Geyser -110.7031627995596 44.7290938400164 Pinwheel Geyser, seen from the overlook beyond Whirligig, hasn't erupted for many years. But its runoff channel provides one of the clearest thermal and chemical gradients in Norris. The brilliant green belongs to acid-tolerant thermophiles, including Cyanidium. This community begins when water cools to l00-126°F. Rust-red mats are colored by iron oxide. The boundary between green and brown mats occurs when acid-tolerant algae reach their upper temperature limit. Return to the main path and continue around the lower part of Porcelain Basin. Look for tracks of bison and elk in damp areas.
Whale's Mouth -110.7053813779863 44.72857541360708 You'll pass Whale's Mouth, which is currently a quiet spring,
Crackling Lake -110.7052701227262 44.72794068666772 and Crackling Lake, named for the popping sounds from springs on its southern shore. The lodgepole pines to your left were killed by thermal activity. Silica penetrates the trees and hardens their bases.
Wooded Area -110.7042387534042 44.72739109057267 From the wooded hill, you can see other geysers and hot springs near Black Growler Steam Vent. When you reach the asphalt path, turn right and then left onto a trail leading to Congress Pool.
Solfatara -110.7016855734691 44.72755493143564  
Congress Pool -110.7013827890362 44.72777802345679 This hot spring was named in 1891 when scientists from around the world converged upon Yellowstone for the Fifth International Geological Congress. Its activity varies from a steaming, dry vent to a boiling murky hot spring to an over-flowing blue pool. It was one of the first pools discovered to contain Sulfolobus, a thermophile that uses sulfur for energy and turns hydrogen sulfide to sulfuric acid in hot acidic water. Newly discovered viruses have been found using Sulfolobus as their host.
Porcelain Springs -110.7006738681711 44.7285643002711 At the junction, turn right to find Porcelain Springs, an ever-changing area. It may be full of water from new springs or geysers, or it could be dry and quiet.
Hurricane Vent -110.70189251889 44.72805557274192 Hurricane Vent once rivaled Black Growler in steam and noise. It has also been boiling and full of steam, with a small waterfall on the far side.
Sunday Geyser -110.7026259152338 44.72806192701152 As you circle back across Porcelain Basin, look for small patches of brilliant blue. They are salts containing sulfur, arsenic, and boron.
Colloidal Pool -110.7029745339249 44.7280617367657  
Ledge Geyser -110.7031559747032 44.72745164850574 Take your time on the steep climb back to the museum. Ledge Geyser may be spouting from its several vents. Its rare eruptions send water 80 feet or more over the basin.
Back Basin -110.7035713714537 44.72626388068957 In contrast to Porcelain Basin, Back Basin is forested and its features are more scattered and isolated. Notice the young lodgepole pines growing up among the remains of a fire that burned through the area in 1988. Their abundant growth provides ample evidence of the resiliency of Yellowstone's ecosystem.
Emerald Spring -110.7043166723615 44.72565432949046 The magnificent color of Emerald Spring comes from the inherent blue of the water combined with the yellow of the sulfur-coated pool. The water in this 27-foot deep pool is so hot—close to boiling—that only the most heat-tolerant thermophiles can survive.
Steamboat Geyser -110.7032041011178 44.72356226081842 Days, months, or years pass between the major eruptions of Steamboat Geyser. The world's tallest active geyser, Steamboat throws water more than 300 feet high, showering viewers and drenching the walkway. For hours following its rare 3-40 minute major eruptions, Steamboat thunders with steam. As befitting such an awesome event, full eruptions are entirely unpredictable. More commonly, it ejects water in frequent bursts of 10 to 40 feet.
Cistern Spring -110.7040793319082 44.72301303983033 Cistern Spring and Steamboat Geyser are linked underground—a fact confirmed in 1983 when Cistern began emptying after each major eruption of Steamboat. Otherwise, Cistern is a beautiful blue pool with constant overflow. Its waters deposit as much as 1/2 inch of sinter each year. Look at the trees around and below this spring; the silica-rich water of Cistern is slowly killing them.
Black Spring Pit -110.7021102371323 44.7222340019808 As you walk up to Echinus, notice the boiling pools on the hill. Black Pit Spring began as a group of small steam vents in the mid 1970s.
Echinus Geyser -110.7020309180699 44.72201279602097 Echinus (e-KI-nus) Geyser is named for its deposits, which look like the spines of echinoderms such as sea urchins or sea stars. Iron oxides cause the red-orange color around the pool and along the runoff channel. Echinus is the largest acidic geyser known; its waters are pH 3-4, almost as acidic as vinegar. Its eruptions are now months to years apart, but could become frequent again. The viewing platforms accommodated crowds that gathered when Echinus was frequent and predictable.
Arch Steam Vent -110.7036446377963 44.7215863081589 After Echinus, the walkway takes you past a number of hydrothermal features. You are traversing dangerous ground. Do not leave the walkways—boiling water may lie beneath the ground.
Mystic Spring -110.7060916478132 44.72132269285264  
Puff 'n Stuff Geyser -110.7061118174495 44.72031466171161 Puff 'n Stuff Geyser often chugs and sprays water a few feet.
Black Hermit Caldron -110.7064630179957 44.71976041422615  
Green Dragon Spring -110.7071324758482 44.7200747474738 Although you can observe the steam from Green Dragon Spring from the main path, descend the lower path to fully appreciate its bubbling gassy water and to glimpse its sulfur-lined cave.
Blue Mud Steam Vent -110.7073394951766 44.7206765656898 Blue Mud Steam Vent, which began as a powerful steam vent, can still be muddy and dry—or muddy and overflowing.
Yellow Funnel Spring -110.7070168967501 44.72097531085645 Yellow Funnel Spring often is roiling and murky. It can also be calm and clear, or dry and steamy. At one time, its pool was lined with sulfur, which accounts for its colorful name. Beyond Yellow Funnel, the trail begins a route new in 2004. Previously, it crossed the flats to Pearl Geyser. However, in 2003 this area became superheated—enough to begin toasting boardwalks and overheating visitors' feet—and a new feature began throwing scalding, acidic mud onto the trail. Ground temperatures continue to exceed 200°F, the boiling point of water at this elevation. The new route takes you around this area, behind Porkchop Geyser, and on to Pearl Geyser.
Porkchop Geyser -110.7081321854505 44.72211012607115 Porkchop Geyser was once a small hot spring that some people said occasionally erupted. It began spouting continuously in 1985. Then, in September 1989, Porkchop exploded, throwing rocks more than 200 feet. Afterward, it became a gently roiling hot spring. In July 2003, Porkchop roiled as if in eruption. This activity, which probably was caused by an increased discharge of carbon dioxide, ceased within a few days.
Pearl Geyser -110.7074272859738 44.72235703469614 Pearl Geyser is a beauty—full or empty. Its eruptions can spray water 8 feet high. When it is empty, you can view its colorful formations and listen to its underground gurgling.
Vixen Geyser -110.7068272253073 44.72297195627458 Between here and Tantalus Creek, the boardwalk passes Vixen Geyser, usually a slightly-steaming hole in the ground on the right side of the trail. If active, you may hear gurgling below the surface and see steam rising—or you may witness a brief, narrow, and tall eruption.
Junction -110.7063902808267 44.72334902596438 At the junction, turn right to view Corporal Geyser, Veteran Geyser, and Cistern Spring before ascending the steep stairs back to the museum. Or go straight to view another small group of hydrothermal features. This route is longer but much less steep than the stairs.
Corporal Geyser -110.7059669187927 44.72334139143749  
Veteran Geyser -110.7056712061968 44.72291700307556  
Palpitator Spring -110.706339876196 44.72390092137107 Palpitator Spring seems to be constantly beating like your heart, with large "palpitations" caused by gas bubbles doming the surface. It has been known to drain completely for several hours, then refill and begin palpitating again.
Fearless Geyser -110.7062635229276 44.72412493102279  
Monarch Geyser -110.7055696926853 44.72431000379032 According to PW. Norris, Monarch Geyser's eruptions in the 1880s shook the geyser basin and discharged huge amounts of water. Monarch remained active until the early 20th century, and resumed much smaller eruptions in the mid 1990s. An earthquake may have caused its increased activity, but the change was short-lived. Today it quietly overflows.
Minute Geyser -110.7062489253848 44.72515583695459 Minute Geyser spouts vigorously 1-3 feet above its crater—much less activity than during the time of stagecoaches. Visitors waiting for coaches amused themselves by tossing coins and other objects into the geyser. Over time, this vandalism plugged the geyser's plumbing, effectively killing it. No one can predict if Minute Geyser will ever again display its former power.
Unnamed Geyser -110.7066269881576 44.72649638309028 From here, the trail climbs slowly up the forested hill. Look for a short spur to the left, which takes you to an unnamed geyser. After passing this feature, the trail begins to offer views of the East Fork of Tantalus Creek and Porcelain Basin, before reconnecting with the trail up to the museum. Norris Geyser Basin is named for P. W. Norris, superintendent of Yellowstone National Park from 1877-1882. He recorded this area's features in detail. Norris also oversaw construction of some of the park's first roads, some following Native American trails.
Trailhead -110.702113516943 44.72615213430068  

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Trip Report: July 12, 2011

The following information was taken from the Norris Geyser Basin Trail Guide, which is available at the trailhead.

Norris Geyser Basin
  • Norris is outside the Yellowstone Caldera, but inside the first and largest caldera.
  • Norris is one of the most active earthquake areas in the park.
  • This is one of the most acidic hydrothermal areas in Yellowstone.
  • Many acidic geysers, which are rare in the rest of the world, are here.
  • Steamboat Geyser is the tallest active geyser in the world.

Norris Geyser Basin is one of the hottest and most dynamic of Yellowstone's hydrothermal areas. Many hot springs and fumaroles have temperatures above the boiling point (200°F) here. Water fluctuations and seismic activity often change features.

Norris Geyser Basin

It's hard to imagine a setting more volatile than Norris. It is part of one of the world's largest active volcanoes. And it sits on the intersection of three major faults. One runs from the north; another runs from the west. These two faults intersect with a ring fracture from the Yellowstone Caldera eruption 640,000 years ago. These conditions helped to create this dynamic geyser basin.

Changing

Each year at Norris new hot springs and geysers appear; others become dormant. Geologic events cause many of these changes. Even small earthquakes can trigger changes in hydrothermal behavior. Some changes are brief; others last longer.

Geysers and hot springs may also create changes in themselves. Some Norris hot springs, like Cistern, rapidly dissolve underground rock. As hot water moves toward the surface, the dissolved minerals deposit along subterranean passages and around the surface vents. Eventually, these deposits can choke off the flow of water. New features may be born as hot, pressurized water seeks a route to the surface.

Unpredictable

Some features in Norris Geyser Basin can undergo dramatic behavioral changes simultaneously. Clear pools become muddy and boil violently, and some temporarily become geysers. Geysers cease erupting or have altered cycles. New features appear. This sudden activity is known as a "thermal disturbance" and can last a few days or more than a week. Gradually, most features return to "normal."

Why this happens is not fully understood. Norris has the greatest water chemistry diversity among Yellowstone's hydrothermal areas. Multiple underground hot water reservoirs exist here and as their water levels fluctuate, concentrations of chloride, sulfate, iron, and arsenic change. Although Norris is known for its acid features, it also has alkaline hot springs and geysers. As underground waters and chemistry shift, they could contribute to sudden dramatic changes in minerals and pH. Further study will help unravel the mystery of this phenomenon.

The Colors of Norris

Many of the colors you see here are evidence of thermophiles (heat-loving microorganisms) and their activity.

Yellow deposits here typically contain sulfur. They form when hydrogen sulfide gas (the rotten egg odor you may have noticed) is converted to sulfur. Some thermophiles live in these areas because they use chemicals like sulfur for energy. They form communities of mats and streamers (formations that look like waving clumps of hair) in the hottest acidic runoff, which measure between 140°F and 181°F.

Dark brown, rust, and red colors abound in Norris and contain varying amounts of iron. Red-brown mats may also contain bacteria and archaea that help build the mats by metabolizing and depositing iron. These iron-oxide deposits often contain high levels of arsenic. These communities form in water below 140°F.

Emerald-green mats color many of the runoff channels of hot springs and geysers here. Algae are the dominant life forms in these mats and contain chlorophyll, a green pigment that helps convert sunlight to energy. Some bacteria and archaea grow in these mats, which form below 133°F.

Dark blackish-green mats form in even cooler water. An alga called Zygogonium forms these communities of mats and streamers.

Color placement within thermal water changes, in part, because temperatures and chemistry change. In a hot spring, for example, the hottest water is closest to a hot spring's vent. As the water flows outward, it gradually cools. This range of water temperature, called a thermal gradient, supports various thermophilic habitats. Chemical composition also changes as water flows from thermal features, mixes with other water sources, and is diluted or concentrated. As temperatures or chemical compositions change, microbial populations?and the colors they create?shift to a location they favor.

Some Like It Hot!

Norris Geyser Basin supports an astounding diversity of life. The majority of species here are microscopic thermophiles?heat-loving microorganisms. They survive in conditions of high heat and acidity or alkalinity that would instantly kill most other life forms.

Thermophiles are included in all three domains of life:

Bacteria This domain includes bacteria that can cause disease, fertilize soil, recycle material, and renew supplies of oxygen, nitrogen, and water. At Norris, some bacteria metabolize iron and other minerals.

Archaea The organisms in this domain were once considered bacteria, but their genes show they are as different from bacteria as they are from animals and plants. Scientists think they evolved long ago when earth's environment was much hotter. Many of the microbes in Norris are archaea.

Eukarya Within this domain are plants, animals, and fungi. Some of Norris's thermophiles?algae?also belong in this domain.

Viruses, which are not included in the three domains, also thrive in Yellowstone's hydrothermal features. The viruses here are different from other known viruses because they survive such extreme conditions.

Accessibility Information

Due to Norris Geyser Basin's rough terrain and highly changeable conditions, please expect uneven ground and steep grades that exceed 8 percent. Rocks and roots protrude into sections of dirt trail. Most of these sections are marked on the map, but may change. Proceed with extreme caution.

Area Trails

If you are staying in Norris Campground, a 1-mile trail connects the campground and geyser basin. This unpaved trail is mostly flat, well marked, and easy to follow. The geyser basin parking lot is typically full throughout summer, so using the trail can save you time and gasoline and help ease parking congestion.

If you began your visit at the geyser basin and wish to visit the Museum of the National Park Ranger, a historic soldier station, we suggest you use this connecting trail. An excellent view of the station, along with an exhibit, can be found at the turnout located on the main road approximately 1/2 mile (0.8 km) north of Norris Junction, on the road to Mammoth Hot Springs.

Geyser Basins: Windows to Earth's Interior

All of Yellowstone's hydrothermal areas are fueled by magma (molten rock) beneath the park. This magma heats water percolating down from the surface along fractures and faults. This superheated water rises back toward the surface, collecting into larger channels that serve as the "plumbing" for each hydrothermal feature.

Geysers form if the plumbing channel contains a constriction. Between eruptions, temperatures in the superheated, pressurized water beneath the constriction build up, creating increasing amounts of steam. Eventually the steam pushes water out of the constriction, water pressure deep in the system drops instantaneously, and the geyser erupts.

Hot springs are features with no plumbing constriction. Superheated water cools slightly as it reaches the surface, and is replaced by hotter water from deeper sources. This sets up a pattern of water circulation, which helps prevent the chain reaction leading to an eruption.

Fumaroles (steam vents) are Yellowstone's hottest surface features. Their underground channel systems penetrate the hot rock masses, but are generally dry. What little water does drain into the fumarole's plumbing converts instantly to steam.

Mudpots form when acid decomposes surrounding rock into clay. This clay mixes with water to form mud of varying consistency and color. Gases bubble and burst through the mud and create the playful plopping so characteristic of these features.

Porcelain Basin

Rainbow colors, hissing steam, and pungent odors greet your senses in Porcelain Basin. This basin pulsates from steam and boiling water beneath the surface. Its features appear and disappear often, but some hot springs and geysers have become relatively stable features.

Take it all in from Porcelain Basin Overlook. You might see a small geyser splashing, sometimes two or three, sometimes none. Notice the milky blue pools?they are saturated with silica, which is the primary component of glass. Norris's thermal waters contain the highest concentration of silica in Yellowstone. Some of the orange color results from minerals containing elements such as iron and arsenic. Thermophiles also create colors you see, such as orange, greenish-black, and emerald green.

As you descend into Porcelain Basin, you'll pass Black Growler Steam Vent, a steady column of steam. A strong steam vent has been in different locations on this hill for many years, and it has always been called Black Growler. No one knows why it disappears and reappears, but Black Growler always roars back.

Norris Geyser Basin

The boardwalk across Porcelain Basin takes you over hot, acidic waters.

Norris Geyser Basin

It also provides a place to observe thermophile communities such as the streamers and mats populated by Zygogonium, an alga dark on the surface but bright green beneath. It thrives in water of pH 2-3 and temperatures of 68-96°F. Also look for the movement of ephydrid flies and other insects feeding off thermophile communities.

Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin

Constant Geyser could catch you by surprise. Its eruptions burst 20-30 feet high but last barely ten seconds. One or more erupt ions may occur within a few minutes of each other; the geyser may be quiet for 20 minutes or several hours.

Norris Geyser Basin

When Whirligig Geyser erupts, its pulsing sound often can be heard around the basin. Its rust-orange color comes from iron that has been oxidized, in part, by thermophiles.

Norris Geyser Basin

Pinwheel Geyser, seen from the overlook beyond Whirligig, hasn't erupted for many years. But its runoff channel provides one of the clearest thermal and chemical gradients in Norris. The brilliant green belongs to acid-tolerant thermophiles, including Cyanidium. This community begins when water cools to l00-126°F. Rust-red mats are colored by iron oxide. The boundary between green and brown mats occurs when acid-tolerant algae reach their upper temperature limit.

Norris Geyser Basin

Return to the main path and continue around the lower part of Porcelain Basin. Look for tracks of bison and elk in damp areas.

Norris Geyser Basin

You'll pass Whale's Mouth, which is currently a quiet spring,

Norris Geyser Basin

and Crackling Lake, named for the popping sounds from springs on its southern shore.

Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin

The lodgepole pines to your left were killed by thermal activity. Silica penetrates the trees and hardens their bases.

Norris Geyser Basin
Norris Geyser Basin

From the wooded hill, you can see other geysers and hot springs near Black Growler Steam Vent.

When you reach the asphalt path, turn right and then left onto a trail leading to Congress Pool.

Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin

This hot spring was named in 1891 when scientists from around the world converged upon Yellowstone for the Fifth International Geological Congress. Its activity varies from a steaming, dry vent to a boiling murky hot spring to an over-flowing blue pool. It was one of the first pools discovered to contain Sulfolobus, a thermophile that uses sulfur for energy and turns hydrogen sulfide to sulfuric acid in hot acidic water. Newly discovered viruses have been found using Sulfolobus as their host.

At the junction, turn right to find Porcelain Springs, an ever-changing area. It may be full of water from new springs or geysers, or it could be dry and quiet.

Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin

As you circle back across Porcelain Basin, look for small patches of brilliant blue. They are salts containing sulfur, arsenic, and boron.

Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin

Hurricane Vent once rivaled Black Growler in steam and noise. It has also been boiling and full of steam, with a small waterfall on the far side.

Take your time on the steep climb back to the museum. Ledge Geyser may be spouting from its several vents. Its rare eruptions send water 80 feet or more over the basin.

Back Basin

In contrast to Porcelain Basin, Back Basin is forested and its features are more scattered and isolated. Notice the young lodgepole pines growing up among the remains of a fire that burned through the area in 1988. Their abundant growth provides ample evidence of the resiliency of Yellowstone's ecosystem.

The magnificent color of Emerald Spring comes from the inherent blue of the water combined with the yellow of the sulfur-coated pool. The water in this 27-foot deep pool is so hot?close to boiling?that only the most heat-tolerant thermophiles can survive.

Norris Geyser Basin

In sulfur-rich hot springs, such as Emerald Spring, some microorganisms use sulfur as their energy source. Byproducts from these reactions can be used by other microbes. This kind of "recycling" ties the various microorganisms into diverse functioning communities.

Norris Geyser Basin

Days, months, or years pass between the major eruptions of Steamboat Geyser. The world's tallest active geyser, Steamboat throws water more than 300 feet high, showering viewers and drenching the walkway. For hours following its rare 3-40 minute major eruptions, Steamboat thunders with steam. As befitting such an awesome event, full eruptions are entirely unpredictable. More commonly, it ejects water in frequent bursts of 10 to 40 feet.

Norris Geyser Basin
Norris Geyser Basin

Cistern Spring and Steamboat Geyser are linked underground?a fact confirmed in 1983 when Cistern began emptying after each major eruption of Steamboat. Otherwise, Cistern is a beautiful blue pool with constant overflow. Its waters deposit as much as 1/2 inch of sinter each year. Look at the trees around and below this spring; the silica-rich water of Cistern is slowly killing them.

Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin
Norris Geyser Basin

As you walk up to Echinus, notice the boiling pools on the hill. Black Pit Spring began as a group of small steam vents in the mid 1970s.

Norris Geyser Basin

Echinus (e-KI-nus) Geyser is named for its deposits, which look like the spines of echinoderms such as sea urchins or sea stars. Iron oxides cause the red-orange color around the pool and along the runoff channel. Echinus is the largest acidic geyser known; its waters are pH 3-4, almost as acidic as vinegar. Its eruptions are now months to years apart, but could become frequent again. The viewing platforms accommodated crowds that gathered when Echinus was frequent and predictable.

After Echinus, the walkway takes you past a number of hydrothermal features. You are traversing dangerous ground. Do not leave the walkways?boiling water may lie beneath the ground.

Norris Geyser Basin

Puff 'n Stuff Geyser often chugs and sprays water a few feet.

Although you can observe the steam from Green Dragon Spring from the main path, descend the lower path to fully appreciate its bubbling gassy water and to glimpse its sulfur-lined cave.

Blue Mud Steam Vent, which began as a powerful steam vent, can still be muddy and dry?or muddy and overflowing.

Yellow Funnel Spring often is roiling and murky. It can also be calm and clear, or dry and steamy. At one time, its pool was lined with sulfur, which accounts for its colorful name.

Beyond Yellow Funnel, the trail begins a route new in 2004. Previously, it crossed the flats to Pearl Geyse r. However, in 2003 this area became superheated?enough to begin toasting boardwalks and overheating visitors' feet?and a new feature began throwing scalding, acidic mud onto the trail. Ground temperatures continue to exceed 200°F, the boiling point of water at this elevation. The new route takes you around this area, behind Porkchop Geyser, and on to Pearl Geyser.

Porkchop Geyser was once a small hot spring that some people said occasionally erupted. It began spouting continuously in 1985. Then, in September 1989, Porkchop exploded, throwing rocks more than 200 feet. Afterward, it became a gently roiling hot spring. In July 2003, Porkchop roiled as if in eruption. This activity, which probably was caused by an increased discharge of carbon dioxide, ceased within a few days.

Pearl Geyser is a beauty?full or empty. Its eruptions can spray water 8 feet high. When it is empty, you can view its colorful formations and listen to its underground gurgling.

Between here and Tantalus Creek, the boardwalk passes Vixen Geyser, usually a slightly-steaming hole in the ground on the right side of the trail. If active, you may hear gurgling below the surface and see steam rising?or you may witness a brief, narrow, and tall eruption.

At the junction, turn right to view Corporal Geyser,

Norris Geyser Basin

Veteran Geyser,

Norris Geyser Basin
Norris Geyser Basin

and Cistern Spring before ascending the steep stairs back to the museum.

Norris Geyser Basin

Or go straight to view another small group of hydrothermal features. This route is longer but much less steep than the stairs.

Palpitator Spring seems to be constantly beating like your heart, with large "palpitations" caused by gas bubbles doming the surface. It has been known to drain completely for several hours, then refill and begin palpitating again.

Norris Geyser Basin
Norris Geyser Basin

According to PW. Norris, Monarch Geyser's eruptions in the 1880s shook the geyser basin and discharged huge amounts of water. Monarch remained active until the early 20th century, and resumed much smaller eruptions in the mid 1990s. An earthquake may have caused its increased activity, but the change was short-lived. Today it quietly overflows.

Norris Geyser Basin
Norris Geyser Basin

Minute Geyser spouts vigorously 1-3 feet above its crater?much less activity than during the time of stagecoaches. Visitors waiting for coaches amused themselves by tossing coins and other objects into the geyser. Over time, this vandalism plugged the geyser's plumbing, effectively killing it. No one can predict if Minute Geyser will ever again display its former power.

Norris Geyser Basin
Norris Geyser Basin

From here, the trail climbs slowly up the forested hill. Look for a short spur to the left, which takes you to an unnamed geyser.

Norris Geyser Basin

After passing this feature, the trail begins to offer views of the East Fork of Tantalus Creek and Porcelain Basin, before reconnecting with the trail up to the museum.

Norris Geyser Basin is named for P. W. Norris, superintendent of Yellowstone National Park from 1877-1882. He recorded this area's features in detail. Norris also oversaw construction of some of the park's first roads, some following Native American trails.

Animals at Norris

Like other hydrothermal areas in Yellowstone, Norris provides a warm respite from winter for bison and elk. They can also find plants growing here year-round and water to drink.

Watch for bison in the spring; they can seem to suddenly appear as they walk about the basin.

Elk give birth to their calves in May. Do not approach calves; adults fiercely defend their young. Bull elk in the fall are also dangerous.

Look and listen for killdeer. They nest on bare ground and will call in alarm if visitors are close by. Also look for swallows, which fly over the basin catching insects to eat.

Norris Geyser Basin is home to many insects associated with thermophiles. It also provides habitat for colorful dragonflies. Look for them in grassy areas near Crackling Lake in Porcelain Basin and Puff 'n Stuff Geyser in Back Basin.