Mud Volcano

Mud Volcano is located on the road between Lake Yellowstone and Canyon. It is a short set of boardwalks to some interesting geothermal features (the boardwalks have plenty of stairs because they go up the side of a hill, so you may have to huff and puff briefly to go all the way around the loop.)

Sulpher Spring is not in the Mud Volcano, but it is located just across the street (with its own parking lot.) Sulpher Spring is a very large hot pool with boiling gases pouring through it.

According to park literature, Dragon's Mouth Spring was previously known as Gothic Grotto, Blowing Cavern and The Belcher. It has been cooling since 1999, which caused the green water in the pool to turn a chalky white shade.

When the first explorers reached Yellowstone in the 19th century, the mud volcano stood 30 feet tall, and would erupt violently, spewing hot mud all over the surrounding landscape. The eruptions repeated every few hours, shooting hot mud to cover nearby trees. But in the 20th century, a crack blew out the side of the mud volcano cone, and now a hot pool seethes at the crumbling base of the old volcano. You can see the muddy pool in my photo, the wall of dried mud behind the pool is the eroding wall of the old cone.

The behavior of the Grizzly Fumarole depends on the viscosity of the mud. If the mud is liquid, the Grizzly Fumarole will be a mud put. However, the mud was dry during our visit, so the hot steam hissed through the cracks.

Black Dragon's Cauldron is violent pool that broke through the surface in 1948. The pool is slowly migrating south. It is supposed to appear black in color, but perhaps that is just a trick of the light.

Churning Cauldron was extremely active during our visit. It continually frothed hot, muddy water, spouting up 3 to 5 feet high right by the boardwalk. It smelled of sulphur here.

Mud Geyser looks like a large lake. At one time, it would erupt in muddy plumes up to 50 feet tall. Currently, the hot spot under the water is moving south, collapsing the bank on the south shore. It doesn't erupt any more, but the lake water churns with the heat and escaping gases. The photograph on the left is the south bank of the lake. The road in the background leads to Lake and Fishing Bridge. The water on the far side of the road is the Yellowstone River, which flows northward here, heading to the falls in Grand Canyon of the Yellowstone.