♪♪ -It's one of the planet's best known landscapes.

♪♪ A breathtaking natural monument.

♪♪ 280 miles long, 19 miles at its widest.

Average depth -- 4,265 feet.

The Grand Canyon.

♪♪ Geologist Karl Karlstrom and Laurie Crossey are its biggest experts.

♪♪ For eight days, they take us on a journey to unveil this extraordinary geological laboratory.

♪♪ -Mother Earth has provided us with places where the secrets are told a little more clearly, and Grand Canyon is one of them.

-After four days of navigating, they get to where they'll be studying the creation of continents, Snowball Earth, and the evolution of life, and where they question the formation of the Grand Canyon.

♪♪ Accompanied by naturalist Jeff Carpenter and two river runners, Glade and Amy, they cross the wildest rapids that are brought to life by the clash between the Colorado River and the oldest rocks of the Grand Canyon... ...this unique place where adventure meets the history of our planet.

♪♪ ♪♪ ♪♪ Chuar Canyon camp on the morning of the fourth day of the trip, Karl and Laurie are about to cross the Colorado River to arrive on the opposite bank.

The crew has traveled about 90 miles and finds itself at the heart of fascinating geological layers that shed light on an essential period in the history of life, the Cambrian.

Here, Karl and Laurie make exceptional discoveries.

-So, we'll go in here, through the wash. -Oh, nice.

-And then back through the wash, and then we'll hop on the rocks and find our way up through the fan.

-Oh, fun.

-Yep.

Hang on, little bump.

All right.

-You're gonna be with me.

We're gonna be digging a little bit in the shale.

-All right.

-Okay.

This will be a good place to start.

Now, you guys probably know about the Cambrian, the so-called Cambrian explosion of life.

These are the rocks that record the first appearance of hard-bodied animals.

Now, that is hard shells.

It's animals that created biomineralized shells.

And Darwin's dilemma -- way back to Darwin -- he noticed there'd be rocks and rocks and rocks with no fossils, and then, poof, across an unconformity, you'd see trilobites and other interesting animals that made shells.

And he thought this was the most amazing, um, sort of appearance, an explosion of life.

And so animals -- And they kept changing very fast.

So this was a time in Earth history which we're really still studying to say, "How did life become so diverse so fast about 510 million years ago, 500 million years ago?"

So these rocks are really important for understanding life on Earth.

-To get the full picture, let's put things into perspective.

♪♪ Life appeared rapidly on our planet about 3.8 billion years ago.

♪♪ For 85% of the history of life, it has consisted of single-celled organisms.

Then, more complex organisms appeared.

They leave virtually no fossil trace, as they have no skeletons.

But in the Cambrian period, 500 million years ago, animal forms suddenly multiplied.

The shell appeared and left its mark on the rocks.

The trilobite, a marine arthropod with over 18,000 species, became extremely abundant and a fundamental animal for the geologists.

-This process of growing a shell is a major evolutionary step that occurred during Cambrian time, and of all of the hard-bodied fossils, the trilobite is the index fossil for the Cambrian.

It went through so many stages, so many changes in the detailed morphology of the shell that biologists, paleontologists, could literally tell where they were in time all across Earth, in rocks of Cambrian age by these changes in the trilobite fauna.

Here in Grand Canyon is the best exposures of trilobite evolution on Earth.

-On the slopes of the Palisades, Karl and Laurie try to find trilobites to precisely date and understand the major changes taking place during the Cambrian.

-4.5.

-4.5.

-Oh, look.

Look, look.

Yeah, look at this.

You know, this was deep in the Earth for a long time.

So it's more a fact that there was muds deposited and then sands on top.

-Yeah.

-And sometimes the muds get a really fine grain right underneath the sands and... -That's kind of an interesting one there.

-It's a little too sandy, but, yeah, you can see the trace fossils.

But these guys down -- -Still not anything more solid, though.

-See this stuff here?

Yeah, that's the good, fine-grained stuff.

-Oh, yeah.

-The muds.

-What's the white?

-Here, lookit.

-Oh, no way!

Look at that.

That's the biggest one so far.

You just dug that out of there.

Look at that.

-That's a, uh... -No way.

-It's nearly a full -- full specimen.

-Nice job.

Wow!

That's incredible.

-Like I say, I'm not an expert on these, but the trilobite experts on our team will look at the shape of the head -- the cephalon, it's called -- shape of the tail -- the pygidium -- the central part, which is the thorax and then the name trilobite is because of the three segments.

But it's little tiny features.

How many ribs, shape of the head, the shape of the tail that tell you about the evolution of early life.

-Wow!

What a find.

-We're finding is that these evolution of life in the Middle Cambrian, it was much faster, much faster than we thought.

We thought this took 40 million years for one species evolves into -- you know, goes extinct, next one evolves, it radiates.

But now we're finding this takes place in less than a million years.

That eliminates some of the possible explanations.

It has to happen fast.

-Totally different.

-And we're still struggling.

I think the community will continue to puzzle about, "How can these changes take place so fast?"

-For the geologists, for Karl and Laurie, the Grand Canyon is an extraordinary place of study.

It offers incursions into key periods of our planet's history.

And it happens that these essential periods, separated by a few hundred million years on a time scale, are only a couple of miles apart on the ground.

Not far from the Palisades, where they're studying the explosion of life, some very rare rocks can be found.

You must walk up a small canyon to reach Chuar Valley.

These rocks bear witness to another captivating period in our Earth's history, a major topic for the last 25 years.

They're in the middle of the desert and talk about ice.

-These rocks, the Chuar group, are only exposed in this part of the Grand Canyon.

And even in Grand Canyon, they're hidden, right?

They're in the Chuar Valley.

You have to hike here to see them.

But they're super important globally.

They tell us about the time just before the Snowball Earth.

-What is this Snowball Earth?

Like, how is it important to us today?

-The planet was undergoing one of the most extreme climate changes of her history.

So we may be going into another extreme climate change now with warmer and warmer climates.

It's hard to predict the future.

So we look to the past sometimes to see how extreme can it get.

And these rocks, just before the most amazing time, when the planet was essentially frozen, the oceans were frozen mostly, to a certain depth, all around the globe.

So it's not like there's a Antarctica and a polar ice cap.

But the entire blue ocean was frozen.

That's called the Snowball Earth.

-717 million years ago, 200 million years before the Cambrian explosion of life, the Earth underwent a phase of extreme glaciation.

The average temperature was minus-60 degrees Celsius.

A layer of ice over 300-feet thick partially isolated the ocean from the atmosphere.

In the space of 4.5 billion years, the Earth was covered almost entirely by ice on three occasions, and this radically changed the chemistry and biodiversity of its surface.

Albuquerque, University of New Mexico.

In their laboratory, Karl and Laurie analyze rocks collected in Chuar Valley.

The sequence of their layers in the Grand Canyon is exceptional.

-Now we can move in here?

-So they pound, crush, reduce them to powder.

♪♪ And make them talk to understand what changed the Earth's climate.

They tell them that the carbon cycle was enormously disrupted during this period.

It was removed from the atmosphere and buried in the sediments to such an extent.

So much so that the Earth cooled to the point of turning into a snowball.

But they also find a wealth of single-celled life in these rocks, in which their paleontology team makes a major discovery about the evolution of life.

-Yeah, it had a lot more debris.

-Life showed up as single-celled organisms very early.

And for 3 billion years, life persisted.

Single-celled organisms got their energy from the sun or from hot springs or...

But in the Chuar group, we saw -- we see the beginning of a new way that life can sustain itself.

-And these organisms displayed features that had not been seen before -- that is, features that something was feeding on them.

In other words, animals.

That was a new evolutionary step.

So that was a predator.

The first predators have been discovered.

-The first predation set off this arms race, where the predators and the prey now are each trying to develop better ways to stay alive, to reproduce, to carry on your species.

So these vase-shaped microfossils and the images that came out of the Chuar group are really a window into a very important process, which has now started in the -- before Snowball Earth time.

-The Grand Canyon is therefore home to the oldest known traces of predation.

And a great mystery.

How did life persist during millions of years of extreme glaciation?

♪♪ Above all, how could it then explode and develop into more complex organisms?

♪♪ ♪♪ ♪♪ In the Chuar Canyon camp, the question of life is approached in a more prosaic way.

♪♪ -Well, we always watch where we're putting our feet because, um, there are Grand Canyon rattlesnakes here, and they might like to hunker down under a rock or under a shrub.

And we want to be careful about when we set up our sleep kits.

If you're sleeping on the ground, especially, you want to wait till you go to bed to put your sleeping bag out because maybe a snake but more likely something like a scorpion could crawl in there.

And it's not that uncommon.

-At the camp, Carp is always on the lookout for signs of animal presence.

Especially lizards, a passion that consumes him.

-In the Grand Canyon, lizards are cool because they're visually conspicuous, and we see a lot of them, whereas a lot of the mammals come out at night.

Desert adjacent to water.

So in these patches of habitat, lizards can be more abundant because they have a rich source of reliable water.

That water is always there.

♪♪ ♪♪ This is Sceloporus magister.

Sceloporus refers to those femoral pores.

Magister means the master or the teacher because it's such a majestic lizard.

Aren't they beautiful?

Sorry.

♪♪ -Carp continues prospecting until nightfall, the moment when everyone gets together to take stock of the day's work and the one to come.

[ Insects chirping ] The next day, the river confronts the oldest rocks in the Grand Canyon.

For Glade, it's a crucial moment in the journey when the rapids come thick and fast.

John Wesley Powell, the first explorer of the Grand Canyon, wrote about these places in his diary.

His words still ring in the ears of the river runners.

-So, it took him 10 days to do what we did in a couple of -- you know, just a few hours of boating, couple of days.

-Mm-hmm.

-"August 13th, 1869.

We're now ready to start on our way down the great unknown.

We are three quarters of a mile in the depths of the earth, and the great river shrinks into insignificance as it dashes its angry waves against the walls and cliffs that rise to the world above.

The waves are but puny ripples and we but Pygmies, running up and down the sands, are lost among the boulders.

We have an unknown distance yet to run, an unknown river to explore.

What falls there are, we know not.

What rocks beset the channel, we know not.

What walls rise above the river, we know not."

-Thank you.

-Yeah.

-Thank you.

-On the morning of the fifth day, the crew arrives at the entrance to Granite Gorge.

♪♪ They are entering the depths of time.

♪♪ They have left the rocks that tell the story of the start of Snowball Earth, just under 800 million years ago.

They go past rocks over a billion years old for a mile.

And now they're getting to the oldest rocks in the Grand Canyon.

These are almost 2 billion years old.

♪♪ Granite Gorge is the most exciting section of the Grand Canyon.

It's where adventure meets the Earth's history.

The river runners call it the Valley of Adrenaline.

And Hance Rapid is the gateway to this world.

-So many rapids.

The boatmen just gets in the tongue and goes down, and that's where the deep water is and the best path.

But, Hance, if you get in the tongue, it takes you into things you wouldn't want to encounter, so you got much more maneuvering than most rapids.

-Yeah, yeah, most rapids, it's just all about that initial setup.

-Yeah.

-But this one, you actually have to, uh, you know, go against the flow to get to a good place, which makes it tricky.

-The thing about our big boats is that you can't change your mind.

-Yeah.

-They're very slow to react.

If you get on a bad path or somewhere you didn't think of, you know, you might be able to get it back.

-Yeah, we're coming on our next chapter into the older and older rocks.

And these rocks here are a billion years old.

That's pretty old.

But we're about to go into the Granite Gorge, almost 2 billion years old.

And the rocks there are very, very hard.

There's granites and there's schists, and they've been deformed deep in the Earth.

And the resulting rock is very, very hard to erode.

So when the river gets to those rocks, it has to steepen its gradient in order to continue cutting.

So the the river sort of feels the rock in the bed and adjusts its gradient so that it can flow all the way to the sea.

It has to do that.

The rapids get harder, more frequent, and the whole river is steeper.

For the boatmen, even run many, many trips, it's always -- it's always a challenge to get through these really hard rapids.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ -Hance Rapid opens onto an overwhelming world.

♪♪ The canyon seems to absorb humans.

♪♪ You feel as if you're standing at the bottom of the Earth.

♪♪ Which is true, in a way.

These rocks relate the formation of the continents.

-I guess the big question is, how does continental crust form?

We know that Earth has continents, it has oceans.

The oceans subduct and disappear.

The continents are forever.

They preserve a record of early Earth history.

-The oldest rocks on Earth are 4 billion years old.

Most of the continental crust was formed before 2,500,000,000 years ago, and plate tectonics set it all in motion.

Part of the Earth's crust move apart or come together as the planet's mantle moves, explaining the formation of several supercontinents in the course of history.

In Granite Gorge, Karl can see how the American Plate is expanding.

-The general model that I have for how continents form is, assembly of small bits of buoyant material against bigger bits, and then more and more collisions of volcanic arcs that were out in the ocean, just subduction zones, but they get smashed into continents and the continent can build, in our case, from Wyoming all the way to Mexico.

That amount of material was forming in the Proterozoic, we call it, between about 1.8 billion and about 1.4 billion.

-So, 1.8 billion years ago, volcanic islands formed and collided with a continental plate on the edge of a supercontinent.

♪♪ These rocks tell the story of the moment when the North American Plate expanded.

They were formed nearly 66,000 feet below the Earth's surface.

They fascinate Karl because they allow him to see what's going on in the depths of the Earth's crust.

For him, traveling here is like a journey to the center of the Earth.

♪♪ These rocks, the oldest in the Grand Canyon, are also the hardest.

They're so hard, they seem to defy the river, which must erode them to pass through and follow its path to the sea.

This battle between rock and water gives rise to the Valley of Adrenaline.

40 miles where the rapids are more numerous and more violent.

40 miles of fury, excitement, and pleasure.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ In the Valley of Adrenaline, the river is sometimes calm, and life on the river is also about encounters.

[ Indistinct conversations ] -Guys, this is my friend, uh, Kurt.

And we got into this bad habit that every time we see each other, we have to play a song or two together.

Yeah.

So it won't be long, but we'll play you guys a little song.

Grab it.

All right.

-Some squirrelly currents in here, huh?

-[ Laughing ] Yeah.

-Hey, man, how you doing?

-Good.

How are you?

-Great.

-Kurt, a river runner, accompanies scientists to the hydrometric station.

They've only just arrived, and Glade has decided that music comes first.

[ Guitar strumming ] ♪♪ ♪♪ -♪ Let me tell ya about a girl I knew ♪ ♪ Her skin was dark and her eyes so blue ♪ ♪ All the things she could do to you ♪ ♪ By walkin' in the room ♪ ♪ Let me tell you about this girl again ♪ ♪ I say y'all never seen such a grin ♪ ♪ Like a tractor beam that pulls you in ♪ ♪♪ ♪♪ ♪♪ ♪♪ [ Cheers and applause ] ♪♪ -These unexpected and shared moments are also what makes every trip to the Grand Canyon unique.

Life here unfolds without any connection to the outside world, punctuated by the flow of the river and the impatient anticipation of certain rapids.

Hermit is one of them.

Technically easy for Glade, but a great thrill for all.

-Whoo!

-Whoo-hoo!

[ All exclaiming ] ♪♪ -I think my all-time favorite would have to be Hermit.

There's nothing like those waves.

It's almost like a roller coaster, you know?

I don't know anybody who doesn't like Hermit.

You could actually -- if you're up on the rim at Hermit's Rest, you could look down at Hermit and you could see the individual waves.

You know, they're so big.

♪♪ -Life on the river is also about the animals you meet along the way.

♪♪ The desert bighorn sheep often hangs on the walls above the Colorado.

They are one of the few species able to move freely in an environment that often acts as a barrier.

-He is so macho.

You are king of the hill, buddy.

We are not coming there.

There he's getting ready to go.

Wow!

Look at him.

-The desert bighorn almost became extinct.

The Grand Canyon population of this species is the only one.

It's never been reintroduced.

This is its home.

The rapids succeed one another.

-[ Laughing ] -You know where every rock is, don't you?

[ Laughter ] -Yeah, because I hit most.

-Yeah, we -- we've left a few dingers on those rocks.

-Karl is constantly taking notes and finding new places to collect rocks.

Laurie watches as travertine, the youngest rock in the Grand Canyon, covers the oldest rocks.

♪♪ For all periods of time blend here.

Time immemorial relates the Earth's history.

More recent times reveal the landscape.

But there's also time that no longer exists, time that has vanished.

♪♪ This vanished time is called a discordance.

The Blacktail Canyon is a staggering place to observe it.

-Don't you love Blacktail Canyon?

-Oh, it's the best place.

It's a museum of the Great Unconformity.

-I think this contact between this rock and this rock has got to be the most profound contact in Grand Canyon.

-So, here we have the Tapeats Sandstone, half a billion years, and beneath it, the basement rock, 1.7 billion.

So we're missing 1.2 billion along that contact.

-Grand Canyon has such an amazing complete rock record, and yet -- and yet -- there's more time missing than is recorded by the rocks in Grand Canyon.

-The Grand Canyon is crisscrossed by lost times, by discordances.

And the most important of these is the 1 billion year gap in Blacktail Canyon.

-So much missing.

So much missing time.

Where does the time go?

[ Both laugh ] -These rocks go back 500 million or 1.75 billion years.

And these, sometimes we call it the aliens.

You just get them mixed up in your mind.

So you're talking millions or billions, but the time -- the time aspect of what geologists contribute is very important for society, for everyone to think about how humans fit into a long continuum of Earth history.

-The Grand Canyon is disturbing because it places humankind in the time scale of Earth and life.

Homo only appeared 2.5 million years ago.

Our species, Sapiens, is 300,000 years old.

We live for about 80 years.

But in the Grand Canyon, we are confronted with the dynamism that has animated our planet for billions of years.

The Earth appeared 4.5 billion years ago.

Rocks are 4 billion years old.

Plate tectonics have been moving continents for 3 billion years.

The North American Plate began to form 2.5 billion years ago.

And the Grand Canyon region joined it around 1,800,000,000 years ago.

Supercontinents make and break up every 700 million years.

Global glaciations take place.

Life diversifies, explodes, dies out, transforms, and multiplies as these evolutions unfold.

But there's one thing you won't find in the Grand Canyon's layers -- its own history.

For it is far more recent than the age of the layers it reveals.

♪♪ ♪♪ -This magnificent canyon, the Grand Canyon, must be one of the -- one of the most incredible questions geologists have.

How does a river carve a canyon, and how does it -- how does a landscape like this evolve?

Powell, I think, way from the earlier Euro-American expeditions, people said, "Well, the river did it.

The river carved it."

Uh... And that's true.

But how and when and how does it result in such a spectacular, spectacular landscape?

-People have puzzled about that idea for over 150 years, in terms of the details of how the canyon carved, and they had some very different ideas about the timing.

Many people, because we see a flat plateau, they think, "Well, it was all a flat surface, like a table, and then the river carved this huge canyon from that point.

But there were rocks here.

And so just as much as we wonder when we look down where all the material has gone, we can look up and say, where is the past rock that we know was deposited in this place?

It's been eroded away.

So it's not just the canyon that formed, it's the entire landscape that's been reshaped.

-Imagine a mile of sedimentary layers placed at the top of the Grand Canyon.

A mile eroded by an event without which the Grand Canyon's existence would have been impossible.

The uplift of the Colorado Plateau.

70 million years ago, the meeting of an oceanic plate and the American continental plate deformed the Earth's crust, creating widespread volcanism in the region, raising the Colorado Plateau and forming the Rocky Mountains.

With this new relief, erosion worked the landscape and attacked the Colorado Plateau.

At the same time, large quantities of water from melting snow flowed down the mountains, carving out a multitude of small canyons on its surface.

So, when did the Grand Canyon appear?

How was it formed?

♪♪ -The genesis of this extraordinary landscape remains a mystery that Karl and Laurie are trying to understand.

The river is the key to the problem.

-This, uh... this map shows nicely what a strange pattern the Colorado River takes when it goes from Lake Powell, goes south...

So it came to here from the Rocky Mountains -- snowmelt from the Rocky Mountains.

It's still going south.

And then, just here, it takes a right-angle bend.

What a crazy river.

And it goes across the Kaibab Uplift.

So this strange pattern of the Colorado River has been puzzled for 150 years.

Powell only floated from Wyoming, noticed that the river crossed an uplift.

Wasn't the only time along the path.

So a very strange river that wants to go over an uplift.

You think it would go around.

But it carves across.

And then this segment takes another turn.

It goes to the south, toward the -- toward the ocean.

And it takes a hard left and goes along this fault, and then it comes over here and finally emerges into the basement range.

So what's the history of this river?

-To understand the history of the river is to solve the mystery of the age and formation of the Grand Canyon.

♪♪ ♪♪ But as the Grand Canyon carves away, it also removes the evidence that geologists constantly need.

Karl and Laurie are looking for the footprints the river has left in its history, an ancient bed now occupied by gravel, lava flows, or travertine.

They seek to capture something that no longer exists, that has vanished.

♪♪ But from far and wide, the Grand Canyon offers clues.

And one of those clues can also be found in the most dreaded spot.

Lava Falls.

Lava covers the landscape.

It has frozen the trace of the ancient river.

And in the exact same place stands a mythical and dangerous rapid.

The river runners even consider that, once past this rapid, the rest of the journey will be smooth sailing, like an exit door to the Grand Canyon.

But the tension mounts when the Anvil of Vulcan appears.

-Vulcan's Anvil right there.

Marks a mile above Lava Falls.

Some people say it's the longest mile on the river.

It's because it's like a mile and a quarter, but... [ Laughter ] Figured I'd read what Powell wrote.

Just a little part of it when he was here.

"August 25th, 1869" -- exactly 154 years ago, to the day.

This is what he had to say.

"What a conflict of water and fire there must have been here.

Just imagine a river of molten rock running down into a river of melted snow.

What a seething and boiling in the waters.

What clouds of steam rolled into the heavens.

35 miles today.

Hurrah!"

-Well, we're in the footsteps of John Wesley Powell.

-On Lava Falls.

How about that?

-That's amazing.

-It's pretty sweet.

-That is.

♪♪ ♪♪ -In your stomach.

Yeah, you start getting nervous.

The last big one.

Not the last one, but the last big, big one.

Never quite -- never quite know how it's gonna go.

-Should be big today, though.

-It should be big, yeah.

We got plenty of water, yeah.

♪♪ -Before crossing the Lava Falls Rapid, the last hurdle in the Grand Canyon, Karl and Laurie want to get closer to the ancient river, the bed of which has been frozen by lava flows.

-So, we're gonna walk up the sort of the trail.

-This, uh -- This gravel is super slippery.

-Sorry.

Yeah.

-[ Chuckles ] -Be careful.

-Yeah.

[ Indistinct talking ] -Well, the thing is -- Look at this strat.

This -- This is like the bottom of the river looks today, except this -- this contact is worth its weight in gold for figuring out how fast the Colorado River is carving Grand Canyon.

And we're interested in how the river carves through solid rock.

So this was at the bottom of the river at some time in the past.

If we measure the height of this level to the present bottom of the river, and if we can know the age of this, we can calculate the rate.

-By calculating the speed at which the river cuts through the rock, Karl and Laurie have solved a question that has agitated scientists since Paul first explored -- the age and formation of the Grand Canyon.

-It wasn't until 6 million years ago that the Colorado River found its very weird zigzaggy path here and carved the Grand Canyon.

5 to 6 million years is a long time for a human, but in geologic time, it's not so long.

-So we had a paleo canyon with a different landscape.

As the Grand Canyon became carved and the river comes down to some of those levels, it finds pathways and integrates the river system so the modern Colorado River has integrated into paleo canyons.

♪♪ -The Colorado River itself only appeared around 6 million years ago when it made its way from the Rockies to the sea.

It also carved out canyons and integrated older ones.

This explains its very strange course.

And ever since, the Colorado has continued to carve out the Grand Canyon.

0.008 inches per year, on average.

The thickness of a sheet of paper.

0.8 inches in 100 years.

But 656 feet per million years.

3,281 feet for 5 million years.

Time does great things.

-Why is Grand Canyon here?

Why is it the most -- one of the most amazing landscapes in the world?

It's because we have this combination of a powerful continental-scale river with snowmelt from the Rockies.

But that wouldn't do it on its own.

We have to have gradient.

We have to have uplift of the Rockies and the Colorado Plateau to give the river the energy to carve down through.

The water wants to get to the sea, and it's going to do it.

It's going to get to the sea.

It eventually reached the sea 5 million years ago.

But it's that combination of uplift of the plateau region and the power of the river that together created this unique landscape.

-The power of the Colorado is never more apparent than at Lava Falls Rapid.

A legendary rapid so feared that river runners give it an acronym -- ABL -- Alive Below Lava.

-Here we're gonna be ABL -- Alive Below Lava.

Hopefully.

-Glade, how's it looking?

-Looks pretty fun out there.

Looks big.

Glad I'm not in a rowboat.

Big Mama Lava.

♪♪ -Lava Falls is often the highlight of the trip.

Whatever the water level, it is always rated 10 out of 10, the highest degree of difficulty.

It's powerful.

Violent.

It drops 36 feet in just 0.02 miles.

The currents clash.

The rocks emerge.

Glade chooses the right side.

♪♪ ♪♪ -Whoo!

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ -Whoo!

♪♪ -Alive after Lava Falls, a rapid in the image of the Grand Canyon.

Majestic.

Fiery.

Complex.

Grandiose.

At the 224th mile, the crew comes within sight of the first place to land -- Diamond Peak.

The height of the mountain is a symbol indicating also the height differences covered since they left Lees Ferry into the depths of time and Earth's history.

♪♪ ♪♪ ♪♪