When my friend Joan and I visited Yellowstone National Park in May 2022, we were interested in seeing other thermal features in addition to the Mammoth Hot Springs. A major part of the Park is actually a super-volcano, with a caldera measuring 43 by 28 miles (70 x 45 km). It has half of all the world’s geysers, as well as other hydrothermal features (i.e., more than 10,000)!

A visit to the Old Faithful geyser was rewarding for Joan, but perhaps less so for me and others who decided to stand outside nearby. (Joan watched from inside a building with viewing windows.)

I’d seen it from afar before but now thought it would be interesting to be closer. When the awaited eruption occurred (happening about every 69 minutes or so in 2022), I hadn’t realized that I would just get soaked and see only spume and clouds! You readers can see an eruption online without getting wet!

Information about Yellowstone often reiterates that the geysers and other hotspots are always changing because of the geothermal dynamics propelling them. Earthquakes can affect them, and human vandalism can also end a geyser’s “life”. For example, in the 19th century, visitors would throw coins into geysers, which eventually plugged up the vents. (No one claims that the visitors pictured here did this; these parents must have been preoccupied keeping watch over their large brood!)

Photo on display in the Park Museum

When I was in high school, our assigned reading included older English texts, including work by Shakespeare. I found the stories interesting, but the language used did not appeal to me, except for an occasional phrase. The line “Fire burn and cauldron bubble” from Macbeth has a nice rhythm and it came to mind when we stopped to watch the mud pots.

The mud pots are hot springs which are so acidic that they dissolve the rock around them. Microorganisms help convert the emerging hydrogen sulfide gas into sulfuric acid; that breaks the nearby rock into a porridge-like clay which bubbles as gases gurgle through them.

Waiting for shapes to emerge from the thick moving masses was not at all boring. Instead, it made for a nice quiet, contemplative time — and judging by how many people were standing quietly and waiting for shapes to pop up, this was a shared experience. A video of one mud pot can be seen by clicking this link.

The area known as the Artists’ Paintpots was more colorful, even though we didn’t have sunny weather to highlight their hues.

There was vegetation here and there, making for some interesting scenes.

The Norris Geyser Basin is Yellowstone’s oldest, hottest and most changeable area. The National Park Service notes: “Norris has the greatest water chemistry diversity among Yellowstone’s hydrothermal areas. Multiple underground hot water reservoirs exist here and as their water levels fluctuate, concentrations of chloride, sulfate, iron, and arsenic change. Although Norris is known for its acid features, it also has alkaline hot springs and geysers.”

Norris has two main areas. The Porcelain Basin is bare of trees and vegetation. The Porcelain Springs, named for the milky colors of the deposited minerals, are the fastest changing area in the Norris Geyser Basin.

Fumaroles, the hottest hydrothermal features (up to 280°F/138°C) dotted the landscape in the Porcelain Basin. Where the steam and gases spewing from the holes are rich in sulfur, the feature is called a solfatara. Where the gases are mostly carbon dioxide, the fumarole is called a mofette. The sound of the fumarole can be quite loud, as in this video, sometimes sounding like hissing or whistling.

The Back Basin area has more wooded scenery. It was fascinating to see that there were mounds of bison dung in various places near fumaroles. I asked a park ranger how the bison could travel in those areas and whether they were ever injured.

She said that groups of bison will rest around the vents in winter. Their heavy fur apparently insulates them well and they can withstand the heat. She did note, however, that bison have been seen with burns on their legs, so they can be somewhat hurt by the heated clay ground.

Visitors should stay alert even when remaining on boardwalks. In 1989, the Porkchop Geyser threw rocks into the air; fortunately, no one was hurt.

In the early Park days, visitors were invited to bathe in the hot pools but that is fortunately no longer the case.

Where thermal colors are green, chlorophyll-containing algae predominate.

Where yellow is the dominant color, sulfur abounds and heat-loving and -tolerant creatures (thermophiles) use it to create energy.

The Cistern Spring is a beautiful pool that shows blue, green and brown colors with sunlight. These colors are produced by thermophilic algae and bacteria. They, in turn, are accompanied by tiny insects, such as ephidrid fly larvae that feed on bacteria. Spiders and dragonflies then feed on the flies.

We returned a couple times to see some of the famous features because the first day we visited them, it was rainy and then snowed with lots of cold wind. There was so much steam we could scarcely see the colored pools of water; only some features close to boardwalks were clearly visible.

Signs warned that it was a windy area, and the warning was certainly warranted! (Even so, some visitors were perturbed and complained about being subjected to sleet and flurries during their outing!)

The Excelsior Geyser used to erupt regularly in the 1880s and then stopped. In September 1985, it erupted again for 47 hours and again stopped. It was dormant and not very visible during our visit.

At Grand Prismatic Spring, which has stunning blue, green, yellow and rusty orange coloring, we saw mostly gray steam and mud-like rivulets on one visit.

I spoke with a man in a group of people including grandma, who was heavily bundled up in a wheelchair. He remarked that they had been there the previous day, when it was warm, sunny and scarcely windy at all. (Spring weather is extremely changeable at Yellowstone, not only day to day but within a day as well.) Their group had seen the beautiful colors of the Grand Prismatic and it made for a perfect outing since they had come to celebrate a wedding held on the spot. That was really an auspicious start to the married life of the lucky couple!

All in all, we didn’t get many spectacular views of the colorful thermals, but we did learn a lot. A future visit with warmer and sunnier periods would be something nice to anticipate. Nevertheless, the cold, windy, and partly wet days certainly did not dampen our overall enthusiasm. The visions of bubbling mud pots will last a long time, too.

Next up: a few blogs with some of my springtime sightings and then a visit back to Yellowstone to see some small mammals and Western birds.