Our tour starts at the Norris Museum. The museum houses exhibits relating to the origins of the geothermal features found at the basin. Two loop trails leave from here. They provide a safe route for viewing the Porcelain Basin and Back Basin.  

Rainbow Colors, hissing steam, and pungent odors combine to create an experience unique in Yellowstone. Porcelain Basin is open terrain with hundreds of densely packed geothermal features; in contrast, Back Basin is forested and its features are more scattered and isolated.

Porcelain Basin
Parts of the whitish rock-sheet before you pulsate from the pressure of steam and boiling water beneath them. A number of geysers and other features here have been born suddenly in small hydrothermal explosions. Some features are ephemeral, their activity lasting a few hours, days, or weeks. A few others have become relatively permanent fixtures in the scene.

Congress Pool
A visit most times of the year will show a Congress Pool that appears pale blue in color. Due to the variable nature of Norris features it is possible to see the same pool looking muddy and boiling violently.

At Norris, "disturbances" of geothermal activity take place annually. No other thermal area in Yellowstone exhibits this phenomenon. Mysteriously features throughout the Norris area undergo dramatic behavioral changes literally overnight. Clear pools become muddy and boil violently, and some temporarily become geysers. These "disturbances" often occur in late summer and early fall but have been observed throughout the year.

Features that typically behave as geysers may display altered eruption cycles or temporarily cease erupting. New features may be created during a disturbance, although they seldom remain long-term attractions at the basin. Disturbances tend to last from a few days to more than a week. Gradually, most features revert to "normal" activity.

Why this happens is not fully understood. Further study will no doubt yield new clues that will help unravel the mystery of this phenomenon and lead to a greater understanding of the earth’s hidden geologic forces.

Black Growler Steam Vent
The hottest of Yellowstone’s geothermal features are steam vents (fumaroles). Black Growler Steam Vent, on the hillside in front of you, has measured 199 to 280 degrees F (93 to 138 degrees C). A plentiful water supply would help cool these features; however, steam vents are usually found on hillsides or higher ground, above the basin’s water supply. They rapidly boil away what little water they contain, releasing steam and other gases forcefully from underground.

Ledge Geyser
Ledge is the second largest geyser in the Norris Geyser Basin, capable of shooting water 125 feet into the air. Because it erupts at an angle, however, the water will sometimes reach the ground 220 feet away. It has at times in the past erupted at regular intervals of 14 hours. The geyser became inactive between 1979 and late 1993.  It erupted on a fairly regular cycle of every four to six days in 1994 and 1995.

Hot Springs of Porcelain Basin
The milky color of the mineral deposited here inspired the naming of Porcelain Basin. The mineral, siliceous sinter, is brought to the surface by hot water and forms a sinter "sheet" over this flat area as the water flows across the ground and the mineral settles out. This is the fastest changing area in Norris Geyser Basin, and siliceous sinter is one of the agents of change. If the mineral seals off a hot spring or geyser by accumulating in its vent, the hot, pressurized water may flow underground to another weak area and blow through it.

Siliceous sinter is also called geyserite. Deposits usually accumulate very slowly, less than one inch (2.5cm) per century, and form the geyser cones and mounds seen in most geyser basins.

Colorful Water
Many of Norris’ features release acidic water. Amazingly living organisms thrive even in the extreme environments of these acid hot springs! The overflow channels of geysers and hot springs are often brightly colored with minerals and microscopic life forms. Hardy, microscopic, lime-green Cyanidium algae thrives in these warm acid waters. Orange cyanobacteria may be found in the runoff streams in Porcelain Basin. From a distance these bacteria look like rusty, iron-rich mineral deposits.

These and other microscopic life forms are links to the emergence of life on earth billions of years ago. They are also a focus of research in the fields of medicine and criminal investigation. New tools for use in such complex areas as AIDS research and DNA "fingerprinting" have been developed from the microscopic thermal organisms found in Yellowstone’s hot springs.

Blue Geyser
Blue Geyser was called Iris Spring in 1886. Due to a misread map label, in 1904 the feature was inadvertently given its current name. It was observed to erupt to heights of over 60 feet from 1993 to 1996. It became almost dormant in 1997 and has remained very quiet ever since. Blue Geyser’s last observed eruption was in February of 1997.

Whirligig Geysers
Little Whirligig got its name because of its close proximity to Whirligig Geyser. Whirligig was so named because while erupting its water swirls in its crater. The orange-yellow iron oxide deposits around Little Whirligig make it one of the most colorful features in Porcelain Basin. It has been dormant for several years.

Cistern Spring
Cistern Spring and Steamboat Geyser are linked underground. During a major eruption of Steamboat, the water in Cistern Spring’s pool drains. Normally Cistern is a beautiful blue pool from which water continually overflows. It is quite creative, depositing as much as 1/2 inch (12mm) of grayish sinter each year. By comparison Old Faithful Geyser and many other thermal features may build at the rate of 1/2 to 1 inch (12–25mm) per century. Cistern Spring’s influence expands throughout the lodgepole pine forest below. This forest has been slowly flooded with silica rich water since 1965. The pioneering lodgepole pine forest at Norris is in constant flux, retreating here and in other areas of increasing heat while advancing in places of diminished thermal activity.

Emerald Spring
A hot spring’s color often indicates the presence of minerals. In a clear blue pool, the water is absorbing all colors of sunlight except one, blue, which is reflected back to our eyes. Here in Emerald Spring’s pool, another factor joins with light refraction to give this spring its color. The 27-foot (8 meter) deep pool is lined with yellow sulfur deposits. The yellow color from the sulfur combines with the reflected blue light, making the hot spring appear a magnificent emerald green.

Hot spring water can dissolve and transport sulfur from underground. The mineral can deposit and crystallize at the earth’s surface, sometimes in hot spring pools.

Echinus Geyser
Echinus (e-KI-nus) Geyser was a perennial crowd-pleaser which typically erupted every 35 to 75 minutes. Late in 1998 this geyser altered its interval and now erupts only a few times per day at best. Its pool fills gradually with water; then suddenly, bursts of steam and water explode 40 to 60 feet (12 to 18 m) skyward. Eruptions usually last about 4 minutes but in the past major eruptions have lasted as long as 118 minutes. The major eruptions were believed to be caused by a secondary water source which has mysteriously vanished. There has not been a major eruption in 3 years. In late 1998 Echinus’ performance diminished and became erratic. As of mid-1999 its eruptions remain unpredictable.

Echinus is the largest acid-water geyser known. Its waters are almost as acidic as vinegar with a pH ranging from 3.3 to 3.6 . Acid geysers are extremely rare with the majority of the planet’s total being found here at Norris Geyser Basin.

Steamboat Geyser
The world’s tallest active geyser, Steamboat can erupt to more than 300 feet (90m), showering viewers with its mineral-rich waters. For hours following its rare 3 to 40 minute major eruptions, Steamboat thunders with powerful jets of steam. As befitting such an awesome event, full eruptions are entirely unpredictable. Recently, Steamboat had one major eruption on May 2, 2000. More commonly, Steamboat has minor eruptions and ejects water in frequent bursts of 10 to 40 feet.

Porkchop Geyser
Dramatic behavioral changes have characterized Porkchop Geyser during the last decade. Once a small hot spring that occasionally erupted, Porkchop Geyser became a continuous spouter in the spring of 1985. The force of the spray caused a roar that could be heard at the museum over 660 yards (603m) away. On September 5, 1989, Porkchop Geyser exploded. Rocks surrounding the old vent were upended and some were thrown more than 216 feet (66m) from the feature. Porkchop Geyser is now a gently rolling hot spring.

Green Dragon Spring
Except on warm summer afternoons, steam frequently fills the cavern of this intriguing hot spring. Visitors must wait patiently for a glimpse of the sulfur-lined cave and boiling green water.

Whale’s Mouth
This hot spring was named by a park naturalist in 1967 because its shape "resembles the mouth and gullet of a giant fish".

Crackling Lake
The name of this thermal feature was proposed by Ed Leigh in 1967 because of popping sounds from nearby springs on its southern shore. It was formerly simply called Spring #39 in Dr. Peale’s publication entitled Gibbon Geyser Basin.

Minute Geyser
Minute Geyser’s eruptions have changed dramatically. Its larger west vent is clogged with rocks tossed in by early visitors when the park’s main road was near this trail and passed within 70 feet of the geyser. Minute once erupted every 60 seconds, sometimes to heights of 40 to 50 feet (12 to 15 meters). Eruptions now are irregular and originate from its smaller east vent. Removal of the west vent’s mineral-cemented rocks would require the use of heavy equipment resulting in severe damage.

Minute Geyser’s destruction stands today as a sad reminder of thoughtless behavior on the part of some visitors.