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Bubbling Mud T ere’s another kind of hot spring here you might want to see. Well, you’ll probably smell it before you see it. A mud pot smells a lot like rotten eggs. A mud pot is a hot spring that has only a

small amount of water in it. Steam and gas bubble up through the mud. T e mud-covered bubbles grow until they pop and spatter. T e water in a mud pot has a lot of sulfuric

acid in it, which is that strong smell you smell. T e acid breaks rock down into clay, changing the landscape as it does. T e clay and water mix together to form a stinky pool. Most mud pots are beige or gray. Yet the

mud pots at Artists’ Paint Pots are sometimes pink. T at’s because there’s a mineral in the rock that colors the mud. Mud pots might not be as exciting as other

features here, but they add to the park’s chorus of sounds. While geysers rumble, hiss, and roar, mud pots gurgle, burp, and pop.

Fuming Fumaroles While you’re keeping an ear out for mud pots, you might also want to listen for fumaroles. Fumaroles are called “dry geysers.” T at’s because the underground water in a fumarole never reaches the surface. Fumaroles release steam and other gases but not water. T ey are the hottest features here. T ey are also some of the strangest. Take a walk along Roaring Mountain, and

you’ll feel like you’re on another world. Steam pours out of the ground. T e steam vents sizzle and hiss. Fumaroles change the land. Few trees and plants can live amid the heat

here. So the land has become mostly barren. It’s a bare and empty place, but we scientists love it. It helps us understand more of what’s going on down below.

FAST FACT: There are only 30 active supervolcanoes in the world. Yellowstone

is the only one located on land. 22 NATIONAL GEOGRAPHIC EXPLORER

Forest of Stone T ere is one more wonder I want to share with you before we leave. It’s a petrifi ed forest. Heat and minerals from melted rock have turned the trees here into stone. Around 50 million years ago, this forest

fl ourished with willows, elms, maples, oaks, magnolias, dogwoods, and walnuts. T en volcanic eruptions from the nearby mountain range buried the forest in ash. Over time, water trickled through the

hardened layers of ash. It carried dissolved minerals. As the water seeped into the trees, the minerals replaced the wood. T e trees turned into stone. Knocked-down trees carried away by mud

and lava fl ows fi ll most petrifi ed forests. Not here. T is place is unique because many of the trees were petrifi ed in the upright position. T at means the eruption was swiſt , and these trees were instantly buried in place. Aſt er being buried, the ash on the surface

slowly wore down into clay. T e clay eventually turned into soil. A new forest grew. T is cycle—from old forest to new forest—takes about 200 years. It’s a process that has repeated itself here for tens of thousands of years. T e Specimen Ridge site has many layers of

forest stacked on top of one another. Water and wind have uncovered the fossilized trees we see today. Yet even more layers of forest still lie fossilized underground, unseen.

Ready to Rumble? I hope you enjoyed taking a tour with me of a supervolcano. T ere’s so much more I want to show you. T ere’s still so much more I want to know about this place. T is supervolcano may not be ready to

rumble any time soon, but it’s alive and well. T e mud pots bubble. T e geysers gurgle. T e hot springs simmer. T ey are all signs of the underground supervolcano at work. I’m going to keep an eye on it, studying the sizzling sights, sounds, and smells of one of the world’s largest volcanoes.

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