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  • Writer's pictureDeborah Kade

Lower Geyser Basin

Updated: Oct 14, 2019

May 12, 2019

Our first stop when entering Yellowstone was at the Lower Geyser Basin.

The half mile (.8k) Fountain Painted Pots Trail takes you through one of the most complex and dynamic hydro-thermal areas in Yellowstone. Here you will find geysers, hot springs, fumaroles, and mud pots.

The geysers in the Fountain Group exhibit a variety of eruption patterns and intervals.

In the spring, the mud-pots are thin, soupy and splash a lot. As the year goes on and there is less water, they become thick and gurgly.

You must walk on the boardwalk. You are cautioned there is thin crust and scalding water so it is illegal to leave the boardwalk.

Dead lodgepole pines near some hydrothermal areas look as if they are wearing white anklet socks, at one time called “bobby socks.” The dead trees soak up the mineral-laden water. When the water evaporates, the minerals are left behind, turning the lower portion of the trees white.

Fumaroles come in all shapes and sizes, but broadly speaking they’re openings in the ground that emit steam and gases – for example carbon dioxide or sulfur dioxide.

A fumarole (or fumerole – the word ultimately comes from the Latin fumus, "smoke") is an opening in a planet's crust which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrogen chloride, and hydrogen sulfide. The steam forms when super heated water condenses as its pressure drops when it emerges from the ground. The name solfatara (from the Italian solfo, "sulfur") is given to fumaroles that emit sulfurous gases.

Fumaroles may occur along tiny cracks, along long fissure, or in chaotic clusters or fields. They also occur on the surface of lava or pyroclastic flows. A fumarole field is an area of thermal springs and gas vents where shallow magma or hot igneous rocks release gases or interact with groundwater.

Fountain Paint Pot

Mudpots are turbulent pools of hot muddy water.

Making Mud

This vat of bubbling mud contains the perfect mix of ingredients to create mudpots:heat, gases, water, volcanic rock, minerals, acid, and even living microorganisms!

Heat loving "thermopiles" consume some of the gases and help convert them into sulfuric acid. The acid breaks down rock to form clay- clay that mixes with water in mudpots.

Recipe for a mudpot:

Heat: derived from Yellowstone's volcano

Hydrogen sulfide gas


thick layer of rhyolite (volcanic rock)

Thermopiles (heat loving microorganisms)

Pinch of minerals

Let volcanic heat and gases rise through Earth's crust.

Boil water deep underground and add to gases.

Process mixture by forcing upward through cracks in rhyolite.

Simmer in large cooking pot, adding water from rain and snow to make a muddy consistency.

Add thermopiles, simmering while they consume gases and help turn mixture into an acidic marinade.

Cook until rhyolite turns into clay.

Garnish with minerals, allowing bubbling action to create swirls of color.

Year after year, this huge mudpot, called Mammoth Paint Pots until 1927, has changed with the seasons. Fountain Paint Pot spits thin, sloppy mud in spring. In drier conditions, thick bubbles of mud and gas ooze through cracks, then burst and collapse, forming cone shaped mounds.

These are mudpots, too.

We missed Fountain Geyser erupting.

Height: 50 - 90 feet (15 - 27 meters)

Duration: 20 - 35 minutes

Interval; : 5.5 - 11 hours

A geyser is a hot spring that throws forth jets of water and steam intermittently.

Clepsydra Geyser

Height: 10- 40 feet ( 3-12 meters)

Duration: nearly continuous

Bison or buffalo?

In North America, both "bison" and "buffalo" refer to the American bison (Bison bison). Generally, "buffalo" is used informally; "bison" is preferred for formal or scientific purposes. Early European explorers called this animal by many names. Historians believe that the term "buffalo" grew from the French word for beef, boeuf. American bison are a different genus than other buffalo in the world.

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