UPPER
GEYSER BASIN (YELLOWSTONE
HOTSPOT)
HYDROTHERMAL
FEATURES
Old Faithful Geyser (above & below), Old Faithful Group,
southeastern Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA.
Geysers are hot springs that episodically
erupt columns of water. They occur in
few places on Earth. The highest
concentration of geysers anywhere is in Yellowstone’s Upper Geyser Basin.
Old Faithful Geyser itself is the # 1 most
famous geyser on Earth. Its eruption
frequency ranges from about a half-hour to about two hours. Full-force eruption columns range from about
100 feet to less than 200 feet tall, and last from over a minute to about 5
minutes long.
The mottled whitish-grayish-brownish
colored rocks at & around the Old Faithful Vent are geyserite, also
called siliceous sinter.
Geyserite is a friable to solid chemical sedimentary rock composed of
opal (hydrous silica, a.k.a. opaline silica: SiO2·nH2O). It forms by precipitation of hydrous silica
from hot spring water. Geyserite is the
dominant material at & around Yellowstone hot springs and geysers (the
Mammoth Hot Springs area is a major exception to this). The silica in the geyserite is ultimately
derived from leaching of subsurface, late Cenozoic-aged rhyolitic rocks by hot
and superheated groundwater. Rhyolite is
an abundant rock at Yellowstone.
Above: 30 July 2012 (looking ~S).
Below: 13 August 2010 (looking ~ESE).
Old Faithful Geyser (above) - eruption and steam plume on 13 August 2010
(looking ~ESE).
Old Faithful Geyser (above & below) - steaming geyserite
mound on 30 July 2012 (looking ~N).
Old Faithful Geyser (above) - post-eruption steam plume on 30
July 2012 (looking ~WNW).
Castle Geyser (above & below), Castle Group,
south-central Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA on 13 August 2010.
Castle Geyser has a large geyserite cone
that appears to have incorporated the remnants of standing conifer trees.
Above: looking ~NE. Below: looking ~SW.
Tortoise Shell Spring, Castle Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August 2010. Located immediately northwest of Castle
Geyser, this constantly boiling spring rarely has geyser-like bursts of water.
Crested Pool (above & below), Castle Group,
south-central Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA on 13 August 2010. This pool
occasionally has boiling water domes.
Shield Spring, Castle Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August 2010. This hot spring is located a little southwest
of Castle Geyser.
Grotto Geyser (right), Central Vents (center),
and Rocket Geyser (left), Grotto Group, north-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012.
Grotto Geyser (above & below), Grotto Group,
north-central Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA on 30 July 2012. The large geyserite
cone of Grotto Geyser is oddly shaped and appears to have incorporated
silicified tree trunks of conifers.
Eruptions here take the form of large splashes.
Central Vents, Grotto Group, north-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. This feature is on the northwestern flanks of
Grotto Geyser’s geyserite mound.
Rocket Geyser (above & below), Grotto Group,
north-central Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA on 30 July 2012. Rocket Geyser is
located just to the north of Grotto Geyser (see the latter in the right
background below). Eruptions from Rocket
Geyser usually occur together with Grotto Geyser’s eruptions.
Variable Spring, Grotto Group, north-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. Activity at this feature consists of
occasional drops of water in the basin, accompanied by relatively small-scale
splashing.
Spa Geyser, Grotto Group, north-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012.
Riverside Geyser along the eastern banks of the Firehole
River, north-central Upper Geyser Basin, Yellowstone Hotspot, northwestern
Wyoming, USA on 30 July 2012. When
Riverside Geyser erupts, the water column arcs over the Firehole River.
Morning Glory Pool (above & below), Morning Glory Group,
northern Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA.
The natural appearance of Morning Glory
Pool was basically all blue, resembling a morning glory flower. The hottest of Yellowstone’s hot spring pools
are bluish-colored - the high temperatures knock out even heat-loving
extremophile bacteria, so the yellowish-orangish-reddish colored bacterial mats
are absent. Incessant tossing of garbage
into the pool by brainless tourists over many decades has significantly damaged
this feature. Park personnel have
removed trash and coins on several occasions.
Unretrieved trash deep in the vent has restricted water movement,
resulting in cooling and the loss of the pale blue coloration. The green coloration shown above results from
“bluish water” mixed with yellowish-colored bacterial mats. When the pool is hotter, bacteria don’t live
near the center (see below).
Morning Glory Pool was originally
surrounded by a geyserite border, which was completely removed by early
tourists.
Above: 30 July 2012 (looking ~NE).
Below: undated photo (National Park Service
signage).
Spiteful Geyser, Morning Glory Group, northern Upper
Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July
2012. The irregularly-shaped crater was
formed by a hydrothermal explosion along a significant fracture in the
geyserite platform.
Fan Geyser, Morning Glory Group, northern Upper
Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012.
Mortar Geyser, Morning Glory Group, northern Upper
Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012.
Giant Geyser (above & below), Giant Group, central
Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July
2012. Giant Geyser has the 2nd tallest
eruptions of any geyser on Earth (Steamboat Geyser at Yellowstone’s Norris
Geyser Basin is # 1). Eruption column
heights have been recorded as reaching close to 300 feet high. Such eruptions involve water volumes
estimated at about 1 million gallons.
Note the very small splashing water in
Giant Geyser’s vent in the below photo.
Bijou Geyser & Catfish Geyser (above &
below), Giant Group, central Upper Geyser Basin, Yellowstone Hotspot,
northwestern Wyoming, USA on 30 July 2012.
Bijou Geyser is the erupting, dark-colored
geyserite cone. Catfish Geyser is the
light gray geyserite mound in the foreground in the above photo & to the
right in the below photo.
Long-term observations at Bijou Geyser
indicate that it has nearly constant eruptive activity.
Mastiff Geyser, Giant Group, central Upper Geyser Basin,
Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012.
Oblong Geyser, Giant Group, central Upper Geyser Basin,
Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012.
Limekiln Spring along the northeastern banks of the
Firehole River, Grand Group, south-central Upper Geyser Basin, Yellowstone
Hotspot, northwestern Wyoming, USA on 30 July 2012.
Chromatic Spring, Grand Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. This feature is not a geyser - it merely
episodically overflows or doesn’t.
Wave Spring, Grand Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. This pool had one eruption in 1990.
Economic Geyser (foreground) and East Economic Geyser
(background), Grand Group, south-central Upper Geyser Basin, Yellowstone
Hotspot, northwestern Wyoming, USA on 30 July 2012. Both pools were once geysers, but eruptions
have not occurred for many, many years.
Key Spring, Grand Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. When water levels are higher, the wet outline
of this feature includes the circular pool at left, the small vent at top
right, and the channel between. The
overall outline somewhat resembles an old-fashioned key, hence the name. Eruptions occurred here in 1988.
Topsoil Spring, Grand Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012.
Turban Geyser (above & below), Grand Group,
south-central Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA on 30 July 2012. Turban Geyser has
frequent eruptions that can reach 20 feet high.
West Triplet Geyser, Grand Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012.
Belgian Pool, Grand Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. This feature is not known to be a
geyser. The absence of a runoff channel
along the margin of the pool indicates that it does not overflow.
Crystal Spring, Grand Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. Crystal Spring sometimes overflows and rarely
has geyser eruptions.
Bulger Geyser (above & below), Grand Group or
Sawmill Group, south-central Upper Geyser Basin, Yellowstone Hotspot,
northwestern Wyoming, USA on 13 August 2010.
Bulger Geyser has frequent, moderately small eruptions (Ex: see
2nd photo below).
Bulger Geyser (above & below) and Bulger’s Hole
(below), Grand Group or Sawmill Group, south-central Upper Geyser Basin,
Yellowstone Hotspot, northwestern Wyoming, USA.
Above: 13 August 2010 (looking ~SW).
Below: 30 July 2012 (looking ~SW).
Bulger’s Hole is the dark, empty hole in
the foreground in the below photo. Upon
comparison with the above photo of the same view, it becomes obvious that
Bulger’s Hole is a novel feature in the Upper Geyser Basin, having formed between
summer 2010 and summer 2012.
Observations by others indicate that
Bulger’s Hole formed in spring 2011.
Sawmill Geyser (above & below), Sawmill Group,
south-central Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA.
Sawmill Geyser is one of my favorite
geysers. Its pool can be completely
drained of water (see above photo), but it frequently has activity (see below
photo). When “playing”, Sawmill Geyser
eruptions consist of a long series of individual bursts of water every few
seconds.
Above: 13 August 2010 (looking ~S).
Below: 30 July 2012 (looking ~S).
Spasmodic Geyser, Sawmill Group, south-central Upper
Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August
2010. Spasmodic Geyser is a multivent
geyser but has two relatively large, deep pools (see below).
Spasmodic Geyser (above & below), Sawmill Group,
south-central Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA on 13 August 2010 - close-ups of the two main vents.
Twilight Spring, Sawmill Group, south-central Upper
Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August
2010. This feature is sometimes filled
with water, is sometimes drained, and sometimes has splash-like eruptions.
Tardy Geyser, Sawmill Group, south-central Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. The geyserite here consists of small-scale to
medium-sized pustules. Eruptions can be
up to 10 to 20 feet high.
Snake Eyes Geyser, Sawmill Group, south-central Upper
Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August
2010. This small geyser first erupted in
the 1990s.
Chimney Cone along the northeastern banks of the
Firehole River, Sawmill Group, south-central Upper Geyser Basin, Yellowstone
Hotspot, northwestern Wyoming, USA on 13 August 2010. The geyserite cone here formed from slightly
overflowing hot spring activity - geyser eruptions have never been
reported. The yellowish-orange and
brownish areas at the center are extremophile bacterial mats that thrive in hot
water runoff.
Churn Geyser, Sawmill Group, south-central Upper
Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August
2010. This geyser occasionally has
eruptions up to 15 feet high.
Gargoyle Spring (Scalloped Spring), Sawmill Group,
south-central Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming,
USA on 13 August 2010. This feature was
formerly a hot spring pool. Vandals
“soaped” this feature (and many other areas in the Upper Geyser Basin) in 1955,
inducing it to erupt. The jagged margins
of the present hole of Gargoyle Spring indicate it erupted violently. The pool has not recovered for over 50 years.
South Scalloped Spring, Sawmill Group, south-central Upper
Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August
2010. This hot spring pool does not
erupt as a geyser. Gradual precipitation
of geyserite along the margins of the pool has resulted in slightly
overhanging, scalloped geyserite shelves, similar to shelfstone travertine in
caves.
Deleted Teakettle Geyser on the northeastern banks of the Firehole
River, Sawmill Group, south-central Upper Geyser Basin, Yellowstone Hotspot,
northwestern Wyoming, USA on 13 August 2010.
North Goggles Geyser, Geyser Hill Group, southern Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August 2010.
Goggles Spring, Geyser Hill Group, southern Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August 2010.
Lion Geyser, Geyser Hill Group, southern Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA. Fairly frequent eruptions occur at this
moderately large geyserite cone, sometimes reaching almost 100 feet high.
Above: 30 July 2012 (looking ~ESE).
Below: 13 August 2010 (looking ~S).
Big Cub Geyser (center) & Lioness Geyser
(right background) Geyser Hill Group, southern Upper Geyser Basin, Yellowstone
Hotspot, northwestern Wyoming, USA on 30 July 2012 (looking ~ESE).
Heart Spring, Geyser Hill Group, southern Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August 2010. The pool outline is somewhat
heart-shaped. This hot spring does not
have geyser eruptions.
Depression Geyser, Geyser Hill Group, southern Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 13 August 2010.
Scissors Springs (above & below), Geyser Hill Group,
southern Upper Geyser Basin, Yellowstone Hotspot, northwestern Wyoming, USA on
13 August 2010. The two water-filled
vents shown above and below make up Scissors Springs. Runoff
channels from the two vents converge and then diverge, resulting in a
pattern somewhat resembling shears or scissors.
Beehive Geyser, Geyser Hill Group, southern Upper Geyser
Basin, Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. Beehive Geyser is a significant and fairly
regularly erupting geyser. The
beehive-shaped cone has a fairly small vent, resulting in a narrow jet of
erupting water up to 200 feet high.
Big Anemone Geyser (center) & Little Anemone Geyser
(upper left background), Geyser Hill Group, southern Upper Geyser Basin,
Yellowstone Hotspot, northwestern Wyoming, USA on 30 July 2012. These two vents have frequent eruptions. Both have an abundance of small to
medium-sized geyserite nodules.
Info. mostly synthesized from:
Bryan, T.S. 2008. The Geysers of Yellowstone, Fourth Edition. Boulder, Colorado. University Press of Colorado. 462 pp.
Schreier, C. 1987. A Field Guide to Yellowstone’s Geysers, Hot
Springs and Fumaroles. Moose,
Wyoming. Homestead Publishing. 96 pp.
Yellowstone Association. 2010. Old Faithful Area Trail Guide. 7 pp.