Yellowstone National Park - Part 3.
Hot Springs, Fumaroles, and More.

Before moving on I would like to take this time to identify the four types of thermal features at Yellowstone; they are Hot Springs, Geysers, Fumaroles, and Mudpots. In Yellowstone National Park there are some 10,000 thermal features including about 500 geysers. Yellowstone contains the majority of the world's known geysers.

Hot Springs – Superheated water cools and circulates as it reaches the surface. This circulation prevents water from reaching the temperature needed to set off an eruption. The many beautiful colors you see in hot springs are caused by light refraction, suspended mineral particles, and heat-loving microorganisms.

Geysers – A geyser is the equivalent of a giant pressure cooker; even though the temperature of water deep down may be well above boiling, the weight and pressure of the water above prevents that boiling from happening. Eventually the pressure builds enough to push the water in the upper reaches up and out, causing an overflow. That overflow, in turn, relieves the pressure on the super-heated water below causing it to flash into steam. That flash is what sends water shooting into the air.

Fumaroles (also called steam vent) – Basically a vent in the earth’s crust. Modest amounts of ground water come in contact with hot rocks underground and are turned into steam. This steam rushes up through a series of cracks and fissures and out the vent. Some times with enough force to create a loud hiss or roar.

Mudpots – Mudpots occur in places where microorganisms help convert hydrogen sulfide, which rises from deep within the earth into clay, which mixes with rising steam and groundwater to form mud of varying colors and consistencies. Our first stop after leaving Old faithful is Black Sand Basin, which is located in Upper Geyser Basin.


This is an unnamed fumarole/hot spring which is continuously bubbling and emitting gas.
It is mainly a fumarole because very little water, if any, leaves the spring but a lot of gas.


Marge does not like the smell of sulfur.

Another unnamed bubbling hot spring.

Marge looking at Emerald Pool

Emerald Pool is a hot spring.
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.


Marge looking at Sunset Lake

Sunset Lake is a large hot spring.
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.


This is the other half of Sunset Lake.

RAINBOW POOL on the left and two small unnamed geysers on the right.
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.
Our Saturn VUE is in the far parking lot.


Runoff from the hot springs and geysers flowing into Iron Spring Creek.

Runoff from the hot springs and geysers flowing into Iron Spring Creek.

CLIFF GEYSER
Temperature 191.8°F Interval irregular. Duration 30 minutes to 3 hours. Height 40 feet.
Named for its cliff-like wall of geyserite formed around the crater and for its location on the edge of Iron Creek. Geyserite is a form of opaline silica that is often found around hot springs and geysers.


We turned down Fire Lake Drive to see the Great Fountain Geyser and passed this meadow.
This herd of buffalo were just waiting for us visitors to pass.




It must be buffalo's lovers-lane. They seemed to be all paired up.



These two had a lovers spat. The bull on the right is sticking his tongue out at us!

Great Fountain Geyser
The geyser erupts every 9 to 15 hours. Great Fountain's maximum height ranges from about 75 feet (23 m) to over 220 feet (67 m). Its duration is usually about one hour but durations of over two hours have been seen.


They do not have a listing for the next eruption of Great Fountain Geyser
It seems to be very quiet so we are moving on. You can see the buffalo tracks in the gray mud.


White Dome Geyser

White Dome is a cone-type geyser. Its 12-foot-high geyserite cone is one of the largest in the park. Its eruptions are unpredictable, but generally occur with intervals ranging from 15 minutes to 3 hours. Eruptions typically last 2 to 3 minutes and reach heights of about 30 feet. Because we have to pack so much into this day, we cannot wait and are moving on.

Bacteria Mat
We are now hiking on a trail in Lower Geyser Basin.
This is the runoff from the Silex Hot Spring and several springs and geysers.


Bacteria Mat
The runoff is very colorful as we near the Silex Spring.


Either the wind blew this hat (lower right of picture) off the wearers head or
there is a sunken body standing under it.


The Silex Hot Spring - 193 degrees F

Red Spouter
It behaves like a fumarole, a hot spring, and a mudpot throughout the year. It is like a hot spring in the winter, a muddy reddish pool in the spring and a steaming fumarole in the drier summer and fall. Today it's a fumarole. These two vents are really smelling up the place. Best to stand up wind!


Fountain Paint Pot (mudpot)

The NP added this to the sign in front of the Fountain Paint Pot.

Evidently this tree does not mind the smell or the results of the runoff.

Leather Pool (Hot Spring)

Buffalo tracks on the boardwalk. They like to walk in the warm water and mud at night when nobody is around. These tracks were stepped on by visitors all day long.

Clepsydra Geyser plays nearly continuously and erupts to heights of 45 feet



“Bobby Socks Trees” on flat, mineralized land near the Fountain Group.
A common sight near active thermal features, these lodgepole pine trees drowned in the super-heated water of shifting thermal activity. Silica penetrated the trees and hardened their bases. The white silicified portions of the dead trees resemble the upper cuff of a type of ankle socks popular in America in the 1940’s and 50’s.


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