From the brains behind brains on, this is the moment of um.

Moment of um comes to you from APM Studios. I'm producer Anna Goldfield.

Hi ya, pals. I've been lounging in the Brains-on library, reading up on my mythology.

My favorite kind of myths are stories that explain something that happens in nature,

like this one from the Klamath, an indigenous tribe living in the northwestern

United States. The legend says that long ago, the chief of the underworld and the chief of the

above world had a fight to see who was the strongest. The mythical warriors battled it out for days,

flinging massive rocks and fire at one another. Kind of sounds like a volcanic eruption,

huh? Anyway, the chief of the underworld decided to climb to the top of a mountain to see his

opponent better, but just as he reached the peak, the mountain collapsed under his weight.

He fell back to his underworld domain. This collapse made a massive hole or crater

in the earth that filled with water and became a huge lake. People today think the source of that

legend comes from the fact that there was once an active volcano in that area, and it did collapse

more than 7,500 years ago.

When it collapsed, it formed a huge hole that became what's now called Crater Lake in Oregon.

Luckily for anyone in that area, that volcano is now dormant, which means it can't erupt.

Huh. I wonder how that happens.

My buddy Cali wanted to know how volcanoes go dormant too, so I asked a geologist to tell us all about it.

The key thing that you need for a volcano is lava.

My name is Kelsey Woody.

I'm an isotope geochemist, and I study how certain chemicals on Earth, so like water and

carbon dioxide, for example, are exchanged between the inside and the outside of the Earth.

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