Lower Geyser Basin

Lower Geyser Basin is located between Madison Junction and the Old Faithful area and includes all four types of features, including fumaroles, hot springs, geysers and mud pots.

The Lower Geyser Basin is the largest geyser basin in area, in Yellowstone National Park. It covers approximately 11 square miles. By comparison, the Upper Geyser Basin only covers about one square mile.

Because of its large size, the thermal features in the Lower Geyser Basin tend to be clumped in widely spaced groups. The easiest grouping to get to and probably the most interesting to explore is the Fountain Paint Pot area.

Many of the thermal features of the Lower Geyser Basin are easily accessed on the one-way Firehole Lake Drive.

Acidity in the steam is responsible for the surface rock in this area breaking into clay. The clay and the steam pushing through it create natural occurrences and the most popular attraction in the basin, the Fountain Paint Pots.

The steam responsible for the paint pots is enough to cultivate the clay and mull its shades of white, brown and gray, but it can't muster the strength or the amount of water necessary to wash the clay away. Additional liquid at different times of the year gives the paint pots their characteristic look of bubbling, blended mud.

Fountain Paint Pots is Yellowstone's most easily accessed large group of mud pots.

Also located in the Lower Geyser Basin is Great Fountain Geyser. Great Fountain is the only predicted geyser in the Lower Geyser Basin and the only predicted geyser in Yellowstone that you can drive to. Predictions for this geyser are posted at the Old Faithful Visitor Center and, when staffing allows, at the geyser.

Silex Spring: Silex Spring is a beautiful blue hot spring. Sometimes, it is possible to see steam jetting into the pool from the vent at the bottom of the pool. This steam quickly collapses as it hits the cooler water of the pool.

Red Spouter: Red Spouter may sometimes look like a small geyser but it is actually a fumarole that sometimes gets drowned by a puddle of water that forms near its vent.

Clepsydra Geyser: Clepsydra is a pretty geyser often erupting to 45 feet. It was named for a mythical water clock. In the early history of the park, it erupted with clock like regularity. After the 1959 Hebgen Lake Earthquake it went into a "wild phase". Since then it has erupted almost constantly, only occasionally stopping after an eruption of nearby Fountain Geyser.

Fountain Geyser is the dominant member of a group of geysers at the Fountain Paint Pots thermal area.

Morning Geyser, which erupts from a vent close to Fountain's, is larger. Morning Geyser is the largest geyser in the Fountain area and one of the largest geysers in the world. Unfortunately, it is seldom active. When active it can erupt as often as every 4 hours to 200 feet high and 100 feet wide. Eruptions last up to 1/2 hour.

Fountain, by contrast, is usually active. It is a fountain-type geyser that erupts jets ranging in height up to 80 feet or more, with most eruptions containing at least a few bursts that reach 40 to 50 feet. Intervals (= eruption start to eruption start) vary from year to year but are commonly about 4.5 to 6 hours, with occasional longer intervals of 11 to 12 hours.

Durations of eruptions are typically about 30 minutes. Occasionally, Fountain departs from its usual behavior and enters so-called "wild-phase" eruption, during which the height is much reduced but the duration can be as long as two weeks.

Fountain is not to be confused with similarly named, and nearby (and larger), Great Fountain Geyser, another of the major features of Lower Geyser Basin, adjacent to the Firehole Lake road.

Great Fountain Geyser sits in the middle of one of the prettiest sinter formations in the park. The sinter forms a series of terraced concentric reflecting pools around the geyser.

Great Fountain is a fountain-type geyser, erupting in a series of bursts through a pool of water. Its interval between eruptions ranges from 9 to 15 hours but its short term average interval is usually stable enough that the eruptions can be predicted to within an hour or two. Great Fountain’s maximum height ranges from about 75 feet to over 220 feet. Its duration is usually about one hour but durations of over two hours have been seen.

Great Fountain erupts in a series of distinctly spaced bursts. The first group of bursts lasts about ten minutes. Then there is about a five minute quiet period followed by another five or so minutes of activity. These quiet and active episodes continue until the end of the eruption. Usually the first period of activity is the tallest and strongest, with the first and sometimes the second burst being the strongest of the eruption. Sometimes, the largest burst will occur during the third active period. This especially seems to occur when the first period has been uninspiring. Rarely, large bursts will continue long into the eruption.

Unfortunately I was unable to see it erupt.

White Dome is a conspicuous cone-type geyser located on the western side of Firehole Lake Drive. Its 12-foot-high geyserite cone is one of the largest in the park.

Eruptions are unpredictable, but generally occur with intervals (= eruption start to eruption start) ranging from 15 minutes to 3 hours. The shortest reported intervals have been 8 to 11 minutes. Intervals between 20 and 35 minutes are most common.

Eruptions last about 2 minutes and reach heights of about 30 feet, the maximum height being attained early in the eruption. As usual for cone-type geysers, the play is continuous for most of the eruption's duration.

Eruptions usually start without warning, although minor spitting may occur a little or immediately beforehand. Eruptions conclude with steam mixed with liquid spray. Between eruptions, minor spitting lasting 1 to 2 seconds may occur. Rarely, a minor eruption may occur involving about 10 to 15 seconds of hesitating, moderately low spouting and splashing.