- [Instructor] What does it mean to be curious?

For my students, curiosity creates opportunities for a bigger and brighter future.

(bright upbeat music) (tranquil traditional music) - Wenatchee, Washington is down there on a perfect late spring evening, and this is Saddle Rock, a pinnacle of volcanic lava that looms above the Columbia River.

There's more than Saddle Rock.

There's many of these pinnacles that are 44 million years old.

That's a new date from new research.

What kind of rock is up here?

What kind of volcano story can be told by studying Saddle Rock?

Hint, it's older than the Cascade Volcanoes.

(tranquil traditional music) (tranquil traditional music continues) Okay, top of Saddle Rock.

This is rhyolite, and rhyolite is very stiff lava.

This is not the kind of volcanic rock that you typically see in the well-known Cascade Volcano line, like Mount Rainier and Mount St. Helens.

It's a pink volcanic rock with these little white chunks inside, little smoky quartz, crystals.

Well, this is very stiff, sticky lava, and so each of these pinnacles is a rhyolite dome, a squirt of very toothpaste-like magma.

It was part of a very explosive volcanic system.

(tranquil traditional music) (tranquil traditional music continues) Saddle Rock, beautiful pinnacle.

There's a whole family of these volcanic outcrops, including this one here.

This is Wenatchee Dome.

Just like it sounds, a dome of lava.

But there's a specific story about all of these outcrops.

They tell the same story with age and chemistry.

Let's look a little bit more carefully at this volcanic outcrop and try to put a story together.

(tranquil traditional music) (tranquil traditional music continues) All right, Saddle Rock, 44 million year old rhyolite, Wenatchee Dome, same stuff.

Castle Rock, Black Thumb, Rooster Comb.

If this is too old for the Cascades and it's rhyolite, what should we be visualizing for this area at that time?

This.

This is a welded tuff.

It's the result of a pyroclastic flow.

An ignimbrite, an ash-flow tuff.

Those phrases all mean the same thing.

The most explosive, dangerous, ground-hugging hurricanes of ash rock gas coming to rest, welding in place with a volcanic vent close by.

This is much closer to a supervolcano story than it is a composite cone volcano.

We're still trying to work out the details of if there's a supervolcano here, or where the vents are, or what the volcano actually looked like, but it's major progress to realize that all of these pinnacles at Wenatchee tell the same story.

(tranquil traditional music) (tranquil traditional music continues) So yes, this is a volcano story, but no, this is not volcano standing on this landscape for 44 million years.

Let's not get carried away.

This is an underground story.

So these pinnacles of rhyolite lava were actually underground fingers of magma working their way up through soft sandstones.

Some of them got to the surface and exploded violently, but these pinnacles are the result of eroding soft sandstone over the last 44 million years.

And what's left standing?

These fingers of frozen magma that, today, preside over Wenatchee, Washington.

(tranquil traditional music) - [Announcer] This series was made possible in part with the generous support of Pacific Science Center.