Sand Basin, an isolated group of the Upper Geyser Basin, was originally
named the Emerald Group by A.C. Peale in 1878. But turn of the century
tourists began calling it Black Sand Basin because of the small fragments
of black obsidian sand which cover portions of the basin.
Black Sand Basin contains a small collection
of jewel-like geysers, and colorful hot springs. Emerald Pool is the
most colorful and famous of these springs. It is a deep emerald green
fringed by an outer ring of yellow and orange. Another colorful pool
is Opalescent Pool. This recently formed pool inundated a stand of lodgepole
pine, creating a stand of white skeletons amidst a rainbow-colored pool. An unusual geyser formed on the bank of
Iron Creek. Cliff Geyser formed a rim or wall-like ridge of sinter around
its crater from which it erupts 30 to 40 feet high.
The famous Handkerchief Pool was once
the drawing attraction to Black Sand Basin. Turn-of-the-century tourists
dropped their handkerchiefs into this small spring. Convection currents
then whisked their laundry away where it would reappear again at the
surface, freshly laundered.
Temperature 144°F Dimensions 28x55 feet. Depth 6 feet. Opalescent
pool has a cooler temperature than other thermal features at Black Sand
Basin. Early in its history Opalescent was a boiling spring, surrounded
by smaller springs. In the early 1950s it was a small dry pool, then
the run-off from Spouter Geyser flowed into it. The increased water
flow flooded the surrounding area, killing the lodgepole pine. Since
then silica has precipitated upon the dead tree trunks creating the
white "bobby sock" trees. This silica, a non-crystalline compound,
slowly impregnates the wood and over time, with the absence of oxygen,
could eventually petrify the wood.
- 98 Minutes
~Telly Award Winner for Nature
Two years in the making
and just released, "The Wonders of Yellowstone" video
has been highly requested, produced in DVD format and is now available.
Take a complete tour of Yellowstone National Park as our Narrator
Cathy Coan guides you to all the wonders of the park including
all the geyser basins, wildlife, waterfalls and much more.
We previously sold
travel packets but these packets, maps and trail guides are all
available at the park for free or minimal charge.
Info or Order Online
Temperature 199.9°F Interval 1-2 hours. Duration 10-11 hours. Height
5-7 feet. Spouter Geyser, once believed to be a continuous geyser,
does erupt almost constantly with only a short 1 to 2 hour interval.
It is a fountain-type geyser and erupts from a splashing, undulating,
blue pool of water. The jets shoot through the pool to a height of five
to seven feet. The crater, formed of sinter with intricate scalloped
edges and rosette beads, drains after an eruption. No subsurface connection
is known to exist with any other spring in the basin. Overflow from
Spouter discharges into Opalescent Pool.
Temperature 191.8°F Interval irregular. Duration 30 minutes to 3
hours. Height 40 feet. A. C. Peale, geologist for the 1872 Hayden
Expedition, named this feature for its cliff-like wall of geyserite
formed around the crater and for its location on the edge of Iron Creek.
An indication of a pending eruption is that the crater nearly fills
with boiling water. As the eruption begins, jets of water explode through
the pool 15 to 40 feet high. This is accompanied by a tremendous amount
of steam. The eruption reaches its highest point the first half hour
and gradually subsides until the crater empties. The interval is irregular,
lasting between a half hour to 18 hours, and there may be weeks or even
years of dormancy. When it is active there are usually one or two eruptions
Temperature 154.6°F Dimensions 27x38 feet. Depth 25 feet. Named
for its emerald green color, it is one of the main attractions at Black
Sand Basin. The color is the result of lower temperatures which have
allowed yellow bacteria and algae to grow on the lining of the pool.
The clear water of the pool reflects the blues but absorbs the other
hues of the color spectrum. The combination of blue and yellow then
produces green. Objects thrown into the pool and natural debris have
caused a further decrease in temperature, resulting in a change of bacteria
and algae growth and thus a change of color. The edge of the pool is
now orange and brown. If the temperature continues to decrease, the
pool may lose its emerald color.
Temperature 161°F Dimensions 100x130 feet. Depth 27 feet. The
edges of this pool display the color of the rainbow, hence the name.
Algae and cyanobacteria are responsible for the varied colors. This
pool has only erupted a few times in the past. During one eruption in
1948 it reached a height of 25 feet. The last known eruption was in
1973. The famous Handkerchief Pool, located along the southern edge
of Rainbow, was a popular pool at the turn-of-the-century. Tourists
dropped handkerchiefs at one end of the pool and convection currents
would pull them under. A moment later they would reappear in another
vent, freshly laundered. The pool has not functioned since 1929 when
it became plugged by human vandalism. It is now a small spouter and
inaccessible because of microbial mats. Underground connections exist
between Rainbow Pool, Green Spring and Handkerchief Pool.
Temperature 180°F Dimensions 145x191 feet. Depth 23.5 feet. Sunset Lake is a shallow thermal pool with a soft sinter bottom and
yellow and orange bacteria and algae edges. The pool discharges into
Iron Creek, and overflows into Rainbow Pool creating a large microbial
mat between the two thermal features. The 1959 earthquake triggered
an eruption of Sunset Lake and the surge of hot water killed the bacteria
and algae in the run-off channels. It has erupted only occasionally
since 1959; during eruption it surges three feet high but may reach
eight to ten feet. No known underground connection exists between Rainbow
Pool or other Black Sand Basin thermal features.