Mammoth in Yellowstone National Park in Park County, Wyoming — The American West (Mountains)

Sulphur Caldron

Photographed by Beverly Pfingsten, June 9, 2011

1. Sulphur Caldron Marker

Inscription. Ten times more acidic than lemon juice, Sulphur Caldron sits on the edge of one of the most active areas of Yellowstone's buried volcano. Sulphur-rich gasses rise furiously here, filling Sulphur Caldron with sulfuric acid. Incredibly, this muddy pool is teeming with life!

Home Sweet Home
Billions of thermoacidophiles thrive in Sulphur Caldron. They convert the pool's hydrogen sulfide gas into sulfuric acid.
The sulfuric acid breaks soil and rock into mud, making this spring a very muddy home.

What is a Thermoacidophile?
Thermo = Heat
Acid = Acidic
Phile = Love
Microorganisms that "love" to live in an extremely hot, acidic environment are called "thermoacidophiles."

pH Scale Basics
If you have ever had "heart burn" from eating acidic foods and used an antacid to relieve the pain, you can easily understand pH basics.
"pH" means "power of hydrogen." Acids release hydrogen ions, and alkaline solutions remove them. Acids and bases neutralize each other.
Thermoacidophiles thrive in an acidic environment that would be deadly to humans. Sulphur Caldron's microbes live in a pool that is almost as acidic as battery acid!

Left Table
pH Scale

Topics.

Paid Advertisement

Click or scan to see
this page online

This historical marker is listed in these topic lists: Environment • Natural Features.

Location. 44° 37.677′ N, 110° 25.997′ W. Marker is in Yellowstone National Park, Wyoming, in Park County. It is in Mammoth. It is on Grand Loop Road. Touch for map. Marker is in this post office area: Yellowstone National Park WY 82190, United States of America. Touch for directions.

Regionally, this marker is in the Bighorn Basin

and in Greater Yellowstone.

It is also in the American Mountain West

and in the Lewis & Clark Corridor.

Globally, it is in North America,

the Rocky Mountains,

the Western Hemisphere,

the Western World,

and the Anglosphere.

Other nearby markers. At least 8 other markers are within walking distance of this marker: Volcanic Landscape (here, next to this marker); Dragon's Mouth Spring (approx. ¼ mile away); Mud Volcano (approx. ¼ mile away); Cooking Hillside (approx. 0.3 miles away); Grizzly Fumarole (approx. 0.3 miles away); Mud Geyser (approx. 0.4 miles away); Churning Caldron (approx. half a mile away); Black Dragon’s Caldron (approx. half a mile away). Touch for a list and map

Photographed by Bill Coughlin, July 30, 2015

2. Sulphur Caldron Marker

of all markers in Yellowstone National Park.

Yellowstone Markers image. Click for full size.

Photographed by Bill Coughlin, July 30, 2015

3. Yellowstone Markers

Two markers can be found at this location. The Sulphur Caldron marker is seen here on the right.

Sulphur Caldron Mudpot image. Click for full size.

Photographed by Beverly Pfingsten, June 9, 2011

4. Sulphur Caldron Mudpot

Credits. This page was last revised on February 16, 2023. It was originally submitted on August 20, 2011, by Bill Pfingsten of Bel Air, Maryland. This page has been viewed 1,180 times since then and 53 times this year. Photos: 1. submitted on August 20, 2011, by Bill Pfingsten of Bel Air, Maryland. 2, 3. submitted on September 24, 2015, by Bill Coughlin of Woodland Park, New Jersey. 4. submitted on August 20, 2011, by Bill Pfingsten of Bel Air, Maryland.