Travel Reference
In-Depth Information
activity in Giant and its neighbors, but nearby Grotto Geyser's eruptions can take the energy
Giant needs.
With eruptions sometimes reaching 250 feet (76 m), Giant has built a massive 12-foot-high
cone (3.6 m) with an enormous central cavity. An estimated 1 million gallons of water (nearly
4 million L) pours out during an eruption. Giant Geyser ranks with the rarely erupting Excel-
sior and Steamboat Geyser as Yellowstone's three most powerful.
A short distance north of Giant, this route joins the paved walkway. Next, the bizarrely
shaped
Grotto Geyser
is the central attraction. Grotto's unique cone has probably been built
up over fallen trees that became encrusted with geyserite. The interval between Grotto's erup-
tions averages six or seven hours but may be more than a day. It may erupt for an hour or
perform a 36-hour marathon, height about 15 feet (4.5m). It's better to take Grotto's picture
when it's not erupting, so that water and steam don't obscure the view of its remarkable form-
ation.
Grotto Geyser has the park's most grotesque cone.
Three geysers near Grotto erupt briefly just before or during Grotto's long eruptions. They
are
Rocket Geyser,
which erupts from its cone in unison with Grotto, sometimes up to 50 feet
(15 m);
Grotto Fountain Geyser,
which can throw a thin stream of water up to 65 feet (20 m)
and precedes most of Grotto's eruptions; and smaller
South Grotto Fountain Geyser,
which
also may erupt just before Grotto. The last two are far back from the walkway.
Spa Geyser
was named for the mineral spring in Belgium that gave its name to all such
springs used for medicinal bathing. Don't try bathing in this spa—the water is over 190°F
(88°C)! Spa's infrequent but explosive eruptions, sometimes as high as 60 feet (18 m), are
linked to Grotto's activity.
R
IVERSIDE
G
EYSER
S
PUR
