Travel Reference
In-Depth Information
When active, Fountain may erupt as high as 100 feet (30 m). Since both Fountain and
Morning Geysers have years-long dormant periods, catching one or both erupting is a treat
you can't count on. Yellowstone's geysers are notorious for changing their eruption patterns.
In past summers Fountain erupted every five to seven hours, whereas in 2012 you were lucky
to catch it once or twice a day.
The geysers of the Fountain Group are interdependent, exhibiting what scientists call
ex-
change of function.
This means that the underground plumbing of each influences the others
a great deal. These geysers are consequently irregular and mostly unpredictable.
Geysers of two other groups, the Kaleidoscope and Sprinkler groups, can sometimes be
seen erupting as you stand on the boardwalks above or near Fountain. There has been more
activity in this area in the past few years than ever before, according to those who've been
watching closely.
Twig Geyser,
at the base of the steps, can be seen erupting a few feet high (a meter or two),
related to Fountain's eruptions.
Jet Geyser
built its formation from six vents along a long break in the sinter. It erupts every
few minutes up to 20 feet (6 m) high when either Fountain or Morning geyser is active.
Spasm Geyser
(near the bend in the boardwalk) plays about 3 feet high (1 m), often begin-
ning to erupt two or three hours before Fountain. Spasm has a yellow-stained cone and pale
green water. Its rocky edge is the result of a hydrothermal explosion this geyser experienced
in 1963.
Clepsydra Geyser
(pronounced CLEP-si-drah), farther from the boardwalk than Spasm
Geyser, clearly exhibits the geysers' exchange of function. If Fountain Geyser is not active,
Clepsydra rarely stops playing, but when Fountain is active, Clepsydra sometimes pauses. Be-
fore Fountain reactivated in the late 1990s, Clepsydra's spurts were as high as 45 feet (14 m);
lately they have been lower.
Clepsydra is the ancient Greek word for water clock (literally, “to steal water”). The name
was applied to this geyser in the 1870s, because at that time its eruptions could be expected
regularly every three minutes. As you tour the park you'll find that early park explorers, offi-
cials, and guides drew on their classical education, choosing Greek and Latin names for many
features.
Jelly Spring
(its official name, although it has sometimes erupted as a geyser) becomes
lined with thick, jellylike masses of cyanobacteria during its long dormant periods. Some sci-
entists think that the microorganisms in Jelly Spring have helped it deposit its gelatinous gey-
serite.
