Travel Reference
In-Depth Information
Great Fountain Geyser erupts straight into the air.
Although there may sometimes be a shortage of park rangers to write the predicted range
of times on the signboard, a knowledgeable geyser gazer is often on hand to predict the next
eruption, using a formula based on the duration of the previous eruption. She or he can re-
fine the prediction after noting the length of time water overflows from the central vent. The
eruption usually starts more than an hour after overflow begins. Your patience will be amply
rewarded by a spectacular eruption! The beginnings of some bursts are accompanied by a so-
called “blue bubble” at the base of the water column. Don't be in a hurry to leave—wonderful
bursts may erupt from a seemingly empty crater during the next hour.
Even the crater of Great Fountain is impressive, with a vent 16 feet (4.8 m) across, surroun-
ded by concentric rings of geyserite that extend to about 150 feet (45 m) in diameter. Its sym-
metry so impressed expedition leader Ferdinand V. Hayden in 1871 that he called this geyser
Architectural Fountain.
This is perhaps the park's largest
fountain-type geyser.
Such geysers have a very broad pool
rather than a cone or narrow vent, and they usually erupt in a series of bursts, sometimes be-
ginning with a blue dome-shaped surge.
