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>> Earth, a unique planet,

restless and dynamic.

Continents shift and clash.

volcanoes erupt. Glaciers grow

and recede.

Titanic forces that are

constantly at work, leaving a

trail of geological mysteries

behind.

In this episode, we investigate

the formation of The Rockies,

A North American mountain

range shrouded in mystery,

flanked by huge slabs of rocks

with ancient sea fossils buried

high in its slopes and crowned

by jagged peaks that geologists

believe were once double the

height they are today.

Scientists piecing together

their story uncover evidence of

massive ice sheets, collapsing

mountains and explosive

volcanic eruptions.

A geological history that

brings us one step closer to

understanding how the Earth was made.

S02x06 The Rockies Original Air Date on December 22, 2009

-- Sync, corrected by elderman -- -- for MY-SUBS.com ---

The Rockies--a majestic

mountain range towering high

above the American West.

It's the longest chain in North

America and the third longest

in the world, stretching over

3,000 miles from New Mexico,

through Colorado, Wyoming and

Montana and north into Canada.

For decades, geologists have

been puzzled about how this

giant mountain range rose from

the plains.

The investigation begins with a

specific type of rock.

>> Here we are in the

heart of the Rocky Mountains,

we're in an amazing place to

begin with, and right here at

Red Rocks we're in the midst of

an amphitheatre of rock.

>> [singing rock music]

>> 13 miles west of Denver,

Colorado, two 300-foot-high

sandstone monoliths slope 45

degrees into the sky.

Each is taller than Niagara

Falls.

Together, they form the walls of

a unique musical venue.

[crowd cheering]

>> But there is more to these

rocks than fine acoustics.

These rocks tell the story of

how the Rocky Mountains were

made.

The story begins with a

mystery, 8,000 feet high in the

Colorado Rockies 60 miles

northwest of Boulder.

All kinds of strange

impressions are found in rocks

scattered over the landscape.

>> We find more than a hundred

species of marine animals right

here at this site. We find

sharks. We find lobsters,

crabs. We find beautiful fossil

clams which are all over the

place.

>> These fossils are crucial

evidence of what existed here

before The Rockies emerged.

>> We're sitting at

about 8,000 feet in the middle

of the Rocky Mountains.

And so when these fossils where

formed, this was below the level

of the ocean. This was below sea

level.

>> This area was covered by a

vast inland sea.

It existed for over 30 million

years and stretched from Utah

to Missouri and from the Gulf

of Mexico to the Arctic Sea.

>> And at this very site,

it would have been very warm,

almost tropical, so

envision maybe a day on the

beach in Florida or something

like that.

>> This warm climate attracted a

unique type of creature that

left behind large, round

imprints in the rocks.

These fossils would play an

important part in the

investigation.

>> This fossil here is

a giant fossil Ammonite and

this animal, this coiled shell

right here, is a relative of

modern-day squids.

So, the closest living relatives

today are squids, nautiloids,

octopuses, things like that.

And so in this big coiled shell

here, the animal would have

lived at this end, and its

tentacles would have stretched

out right here.

And this animal is really quite

remarkable. It's about the size

of a truck tire, and this is

incredible because most

Ammonites aren't this big.

>> Nowhere else have scientists

found a greater number of these

prehistoric creatures than here.

Miller has come up with a

theory why so many of them came

to this area.

>> We think this particular

fossil here was a female

Ammonite. And we think that in

part because male squids are

smaller than female squids by a

lot. So just looking around the

fossil deposits here, we've

found a male Ammonite, this

small one here.

So compare the size of this guy

to this very big one here. And

when we look across this

landscape, we find mostly these

big Ammonites. And so we think

that maybe all these females

got together to spawn and then

died after they spawned.

>> When the Ammonites became

extinct, the map of North

America looked completely

different.

To the north, the Canadian Rocky

Mountains already existed.

To the south, the American

Rockies had yet to rise.

The date of the Ammonites'

extinction holds a key to when

they first emerged.

>> These animals died

about 70 million years ago

in the middle of the western

interior seaway. And so we know

at that time, about 70

million years ago, that this

site was below sea level.

So we know then that the Rocky

Mountains had to rise from that

seaway some time after

70 million years ago.

>> Today, all that is left from

the ancient sea floor are these

fossilized remains high in the

Colorado Rockies.

Next, geologists needed to find

out what pushed the seafloor up.

The investigation moves to

these slabs of rock flanking

the Rockies just outside

Denver, Colorado.

They are known as the flatirons,

and they are part of the same

formation that make up the Red

Rocks Amphitheater.

These slabs of rock are

unusual, because they contain

holes--holes that make the

flatirons appealing to climbers

and geologists alike.

>> So when we go

climbing in the flatirons, we're

climbing on really nice

hand-holds, in some cases

hand-holds that have been

formed either by the pebbles in

the rock or by zones of

fine-grained material that are

easily removed by erosion, the

shales and the silt stones.

Those layers get removed

leaving a notch for the hands

to go in, and it makes

for fantastic climbing.

>> The holes are a clue as to

how these strangely tilted

flatirons were formed.

>> The layers themselves, the

different grain sizes in the

layers, the silt, the sand, the

pebbles--this tells us that

these are sedimentary rocks.

>> Sediments form in water when

sand and small pieces of rock

settle on the ground.

Over millions of years, they get

compressed into layers of rock.

Taking a closer look, Lester can

find out more about the

surroundings they formed in.

>> These were not just deposited

in any kind of sedimentary

situation, but they were

deposited in rivers capable of

transporting big particles and

busting 'em up as it goes along.

>> Sheets of sand and gravel

built up a thick sedimentary bed

like a layered cake,

but stream deposits are rarely

more than a few degrees from

horizontal.

>> These rocks--you can see the

layers and the layers in the

flatirons behind me--are 60

degrees.

>> Something caused these vast

slabs to be tilted.

The investigation moves 10

miles northeast to Flagstaff

Mountain, located in the outer

ranges of the Colorado Rockies.

>> I'm standing here

right next to a miniature

flatiron. It's tilted like the

flatirons at about 60 degrees.

It's steep. How did it

get that way if it was

originally a stream gravel

deposit?

>> The answer lies in the darker

rock underneath.

It is granite and looks

completely different to the

flatiron rock above.

>> There's no layering

in this rock, unlike the

flatiron rock which does have

layering.

There's no pebbles in this

rock, unlike the flatiron rock

which does have pebbles.

>> A close-up investigation of

the granite reveals that it is

full of minerals.

This offers another clue to how

the Rockies emerged.

>> So I've picked up

this granite here and taking a

look at it, I see quartz and

feldspar and a little bit of

mica in here, very

characteristic of a rock like

this that has cooled from a

magma, from a liquid rock.

>> Among the minerals is iron.

It is responsible for the dark

color of the rock.

The precise quantity of iron

tells scientists the depth at

which the rock was formed.

>> So we've taken this

rock into the laboratory and we

do the chemistry on this rock,

and we can actually determine

that not only did cool and

crystallize at depth, that

depth we can estimate at about

15 miles down.

It's now at the surface. How

did it get here? It's been

pushed up by the rise of the

Rocky Mountains and in doing

so, look what it's done to the

flatiron.

>> Scientists investigating the

Rocky Mountains have found two

clues about their early history.

Ammonites on a site 8,000 feet

high are evidence that the area

was once under the sea.

Traces of iron in granite

is evidence that

rock pushed up from 15 miles

below the surface

tilting the flatirons.

And it didn't just happen here

but along approximately 1,000

miles of the American Rockies.

Geologists now needed to find

out what monumental forces were

responsible for this massive

upheaval.

100 million years ago, most of

North America was covered by a

vVast inland sea.

70 million years ago, the sea

retreated and the Rocky

Mountains began to rise, forming

a great mountain range.

Scientists trying to piece

together their geological past

needed to solve the mystery of

what lifted them up.

A force capable of that amount

of heavy lifting would have to

have been on a global scale.

Geologists believe this force

was caused by plate tectonics.

The Earth's crust is broken up

into a series of interlocking

plates.

These plates are continuously

on the move.

Over millions of years, they

collide and break apart,

forming new continents and

geological features around the

world.

When The Rockies formed, two of

these plates smashed into each

other at the American West

Coast.

>> What we know is

that at the time of this

granite uplift on the western

margin of North America, ocean

crust and oceanic plate was

subducting beneath the North

American plate, and it was doing

so at a high rate of speed.

As such, it was transferring

stress into the interior of the

continent.

>> As the two plates moved

towards each other, they

squeezed the crust.

Over millions of years, it

folded and buckled forming tall

mountains.

This was the birth of the

American Rockies.

But a mystery remained.

How did the collision of two

tectonic plates at the western

edge of North America cause the

rise of the Rockies 500 to 1,000

miles inland?

>> Mountain ranges

that form on the margins of

continents are pretty easy to

explain, or where continents

have collided. Where India

slams into Asia, we get the

Himalayas. Where oceanic crust

dives beneath the continental

margin in the northwest,

the Cascades, or in

South America, the Andes

Mountains.

But these mountains here in the

middle of a continent are much

harder to explain and they've

been an enigma for decades.

>> Only recently geologists have

come up with a plausible theory.

They suspect the Rockies formed

along a line where the crust is

very fragile.

>> What happens when

the continent gets compressed,

especially if there's a weak

zone or a zone that's prone to

buckling, it rises.

That's what's brought this

granite to the surface.

>> Geologists now understood how

the Rockies rose and they had a

date for when it happened,

but what were these early

mountains like?

How do they compare to the

mountains of today?

On a site in The Rockies 70

miles northwest of Denver,

geologists find a clue.

>> The mountains that

we see here today aren't the

mountains that were around

millions of years ago. They're

always evolving. Rivers are

shifting. Peaks are shifting.

It's a very dynamic process.

It's almost as if the mountains

are alive themselves.

>> Miller sets out to estimate

the height of the early

mountains. But how can you

measure something that is no

longer there?

Once more, fossils provide the

evidence he is looking for.

>> What's amazing about

collecting fossils is that

you're really the first person

to see this when you crack open

a rock.

It's the first time it sees

light again after 60 million

years.

>> Miller has uncovered a 60

million-year-old fossilized

leaf.

>> It's from a tree that grew

here just 10 million years after

the Rockies began to form.

And intriguingly, this leaf

holds a clue to the height of

these early mountains.

Or more precisely, it's the

edges of the leaf, known as

leaf margins.

Botanists know that in colder

temperatures, the margins tend

to have more teeth than leaves

that grow in warmer areas.

>> Leaves with teeth

do better in colder climates

because teeth are actually

really advantageous in

ump-starting growth at the

beginning of the growing season.

In this case, you can see this

beautiful fossil leaf here with

teeth, and each of the teeth are

little hot-beds of

photosynthesis. So when that

leaf first comes out of the bud,

it gets a jump-start on leaves

that don't have teeth.

>> Miller uses this information

to find out about the height of

the young Rocky Mountains.

In a simple but powerful

technique, he compares the

number of leaves with teeth to

those without.

>> If you go to a

particular area and you pick up

all the species of leaves that

are there from the trees that

are growing in that area and

you compare the number of

species that have teeth to the

number of species that have

smooth margins, that gives us

some idea of what the

temperature is.

>> So the higher the proportion

of plants with jagged edges

compared to plants with smooth

edges, the colder the

temperature of the site.

And the colder the temperature,

the higher the mountain.

>> So if you

got into a hot-air balloon here

today and you floated straight

up into the atmosphere, the

temperature would decrease in a

aery predictable way. And it

turns out that for about every

mile you go up in the

atmosphere, you lose about

20 degrees fahrenheit.

So if we know how temperature

changes with elevation, we can

back out elevation from those

estimates of temperature.

>> To work out the height of the

early mountain, Miller needs to

compare samples from two areas--

one at the base of the mountain

and one at the top.

Fossils found at the base of

the Rockies near to present day

Denver have an amazing story to

tell.

These ancient leaves are

incredibly similar to plants

growing in the tropics today.

>> So after the Rockies

rose, down in the area of

Denver, it was sub-tropical and

tropical forests. We had palms

and cycads and canopies like we

see in the tropics today.

Up here, we had a forest that

looked probably more like a

forest that grows in North or

South Carolina on the east

coast of the U.S.

>> By comparing the ancient

fossil leaves from the top of

the mountain with fossil leaves

from the foot of the mountain,

Miller has come up

with a surprising conclusion.

>> Turns out that

the fossil leaves here are

predominantly toothed, as

compared to those that are in

Denver, which are predominantly

smooth margined.

And it turns out the ones in

Denver grew in a climate that

was about, on average, about

75 degrees fahrenheit.

The ones up here grew in a

climate that was probably about

50 degrees fahrenheit.

So we know how temperature

changes with elevation. That

means that this site when these

fossil leaves were deposited,

was about a mile higher than

Denver.

Today, it's only half a mile

higher. So, 60 million years

ago, the mountains would be

twice as high as they are today.

>> After the Rockies emerged

from the sea, it took them 10

million years to rise.

60 million years ago, they

reached spectacular heights of

28,000 feet, rivaling the

Himalayas today.

The deep history of the Rocky

Mountains is beginning to take

shape. A weak line in the crust

explains why The Rockies rose

500 to 1,000 miles inland.

Fossil leaves show that the

young Rocky Mountains were once

nearly twice their size.

Half of the rock that formed

them originally has vanished.

Scientists are now trying to

unravel the processes that cut

them down to the size they are

today.

100 million years ago, a vast

inland sea covered the area

where the American Rockies

stand tall today.

70 million years ago, the sea

retreated as The Rockies began

to rise. 60 million years ago,

the Rocky Mountains reached

their pinnacle, towering into

the sky with peaks over 28,000

feet high, rivaling the

Himalayas. Since then, the

entire mountain range has lost

nearly half its height.

Geologists investigating the

history of the Rockies are

trying to discover what

happened to the billions of

tons of rock that went missing.

The investigation starts with a

mystery at the Owl Creek

Mountains in the Wyoming

Rockies.

The mountains are sliced by a

river that has formed a deep

canyon.

>> Well, the Wind River

is very perplexing.

It chose to take a straight

path right through the core of

a major mountain range. This is

not the way that rivers

normally act. Usually they'll

take the easiest route,

which is downhill. But this

river cut right through a major

mountain range and has been

a mystery. It's a very

perplexing issue to early

geologists in the region.

>> This river led to confusion

as early as 1806 when Meriwether

Lewis and William Clark mapped

the area during their famous

expedition to explore uncharted

territory in the west.

When they came to the area

around the Owl Creek Mountains,

they assumed there were two

rivers.

North of the mountain flowed a

river which they named

"Bighorn", thinking it was

different to Wind River in the

South.

But later surveys showed that

the Bighorn and Wind River are

in fact one river that

channeled through the mountain.

Recently, geologists have come

up with a possible answer--an

answer that could also explain

what happened to the once

towering peaks of the Rockies.

They proposed that millions of

tons of rock eroded away,

filled in the valleys, and

covered the lower parts of the

mountains.

It completely changed the

terrain.

>> At one point in

ancient history, the basins in

Wyoming were filled with

sediments that had eroded off

the mountains.

This allowed the river to be at

a higher plain and meander

wherever it wanted to on its

course.

>> As the water flowed, it

carved deep into the sediments

and rock underneath.

>> Eventually, it

cut down a channel into the

mountain and it eventually

excavated right through the

mountain.

>> But this is just a theory.

Now geologists needed to find

proof on the ground.

The search is on for the rock

yhat eroded from the early

Rockies.

The investigation moves to a

series of thousand-foot-tall

hills in the Powder River basin

in Wyoming.

Known as the Pumpkin Buttes,

they stand tall in an otherwise

wide, empty landscape.

Hidden behind the horizon are

the Bighorn Mountains, the

nearest range of the Rockies.

These hills are not formed from

solid rock but a collection of

rubble.

>> This rock, which

we find all over the top of

Pumpkin Buttes in wyoming, is

granite. The closest granitee

find to this area is the Bighorn

Mountains, nearly a

hundred miles to the west.

>> The round shape of the

granite rocks is further proof

that they traveled from afar.

Tumbling downhill in rivers and

kandslides rounded them on

their journey over millions of

years.

This was a crucial step in the

investigation tracing the

missing rock from the early

Rockies.

Rock and cobbles eroded down

from the Bighorn Mountains and

filled up the basin to at least

1,000 feet, the height of the

Pumpkin Buttes.

>> The Pumpkin Buttes

are unique because this used to

be the actual surface level of

the basin itself.

The rest has been eroded away,

a thousand feet of sediment, to

the basin that we see now.

>> But the rubble found here is

nowhere near enough to have

covered the Owl Creek Mountains.

Mclaughlin traveled to Darton's

Peak, 100 miles west in the

Bighorn Mountains.

On a cliff 9,000 feet high, he

finds granitic cobbles that are

strikingly similar to the ones

on the Pumpkin Buttes.

They, too, are from the core of

the Rocky Mountains.

>> The core of the

Rocky Mountains are made

extensively of granite, much

like what you see here.

These are from the Bighorns

that have been transported

down, rolled, and smoothed along

their way to create these

smaller boulders and cobbles.

>> This is strong evidence that

cobbles eroding from the

Rockies filled in the basins

and valleys to at least 9,000

feet, slowly burying the

Mountains under their own

debris.

Where once the mighty Rockies

stood, there was now a gray,

barren plain with only the

peaks of the old mountains

piercing the surface.

The same process has happened

in other mountain chains, too.

There is evidence that the

European Alps were also cut in

half by erosion.

At their base, scientists found

hills formed out of millions of

tons of rock that had cascaded

down and reduced their height.

But the story of the eroding

Rockies wasn't over yet.

After erosion turned the

landscape into a gray cobble

field, another disruption

happened.

Evidence for this is a layer

covering the top of the cobbles.

>> It's very light.

It's very fine-grained.

It's actually a volcanic ash.

As you can see, it's made of

very, very fine-grained

sediments compared to this

boulder conglomerate, which is

made up of big hunks of rock.

It sits directly on top of this

unit, and it was laid

horizontally from mostly ash

fall.

>> This fine-grained ash

suggests huge volcanic eruptions

nearby. They spewed out thick

clouds of hot air, ash, and

volcanic rock, which settled on

the ground. Radiocarbon dating

the rock revealed that it

happened 25 million years ago.

>> Ash was deposited as it came

out of the sky as plumes.

Most of it came from the west

and was deposited in basins

across Wyoming.

>> After the lower Rockies were

buried by their own rock,

volcanic ash settled on top and

covered the area with a thick

white sheet.

>> At the time of

the deepest basin-fill of this

volcanic material, all you would

see in this area would be the

very tops of the peaks exposed.

The rest would be large,

extensive lateral ash sheets.

>> Erosion and volcanism

completely transformed the

terrain and buried The Rockies.

But then over millions of

years, rivers flushed out the

eroded rock.

Most of it is thought to have

ended up in the Missouri and

Mississippi rivers from where

it was transported into the sea.

What's left are the mountains

we see today.

This also confirmed the theory

geologists had about the

formation of Wind River Canyon.

The incredible amount of infill

buried the Owl Creek Mountain.

Wind River flowed on top and

began carving into the mountain,

creating the canyon we see

today.

The investigation into what

happened to the early Rocky

Mountains reveals two major

clues.

Granite found on the Pumpkin

Buttes is evidence that the

early Rockies dumped their

eroded rock into the basins.

Wind River Canyon cutting

straight through the Owl Creek

Mountains is evidence that the

Rockies were buried by their

own debris.

The once mighty Rockies had now

been cut down to nearly half

their original size,

but the story was far from over.

Before they became the

Mountains we know today, they

would have to endure an even

greater assault.

70 million years ago, a great

inland sea disappeared and the

Rocky Mountains emerged from

yhe sea floor.

60 million years ago, they

reached their peak height--

twice what it is today.

Then for millions of years, the

Rockies slowly eroded away to

half their original height

until 3 million years ago

another dramatic chapter in

their story began that would

transform them into the

Mountains we know today.

Geologist and photographer Bob

Anderson takes to the air.

He is looking for clues that

will tell him how the mountains

have evolved.

First, he flies over Boulder

Canyon in the Colorado Rockies.

It is an area that has remained

almost unchanged over millions

of years.

>> So, this is Boulder

Canyon we're flying up right

now and you can see how the

river has incised maybe a few

hundred feet down into

otherwise relatively rolling

terrain.

>> The mountain peaks that

existed on the young Rocky

Mountains were rounded off as

rivers and streams eroded the

rock.

>> It's this rolling terrain

that the landscape looked like

in the aftermath of

the mountain-building event that

ended about 50 million years

ago.

>> But as Anderson climbs higher

to Longs Peaks in the Rocky

Mountain National Park, the

terrain changes.

Instead of rolling hills, there

are rugged mountains with

steep, jagged cliffs.

It's evidence that another

force has been at work.

The most famous of these cliffs

is "the Diamond".

Named for its shape, it's a

vertical wall with a sheer 900

foot drop.

The summit, about 45,000 square

feet, is the same size as a

football field.

>> Well, we're flying

beside Longs Peak, one of the

biggest climbing

challenges in The Rockies.

For a century, it's been a

climbing mecca.

It's a gorgeous intact piece

of rock.

>> This awesome wall is the most

difficult climb in the whole of

the Rockies, and since it was

officially opened to climbers

in 1960 has claimed over 50

lives.

Back on the ground,

Anderson is looking for

evidence that will reveal the

processes that shaped the

jagged peaks.

On a hillside, he finds

mysterious large boulders

scattered across the valley

floor.

[tapping rock]

A closer look uncovers some

secrets about their origin.

>> I'm standing in

front of a rounded boulder that

itself is sitting on a smooth

bedrock outcrop.

Both the boulder and the

outcrop are covered in lichen

here of green to black to

gray colors, and therefore I had

to whack off a piece of the

rock in order to see inside the

rock.

And indeed it is different.

The minerals that I see and the

texture of the rock is

different from the underlying

rock. And therefore the rock is

foreign to this particular site.

>> Anderson searches the ground

for more clues as to how this

massive boulder got here.

Nearby, he finds a smooth

surface with very fine scratch

marks.

>> I'm sitting on a

polished surface. This little

piece right here is smooth to

the touch. And if I look at it

in a certain way that the light

glints off of it just right, I

can see that there are

scratches running in this

direction across the surface.

>> The only force that could

have produced these fine,

parallel scratches on the rock

is ice, and lots of it.

It's a clue that a massive

glacier once filled this valley.

>> And that tells me

that the glacier came

down-valley, came across this

surface and eroded it.

Each one of these scratches

corresponds to a sand grain

embedded in the sole of the ice

that just like sandpaper

smoothes off the surface. So

zillions of sand grains over

thousands of years will have

eroded this surface smooth.

>> As glaciers flowed down the

valley, they picked up rocks

and grit.

The ice pushed down on these

cutting tools with the weight

of over a thousand fully loaded

garbage trucks.

It left scratch marks all over

the Rockies up to 1,000 feet

high.

This is evidence that a massive

wall of ice covered this part

of The Rockies and shaped the

mountains.

The ice ripped out the rock

from the valley walls and left

behind the jagged cliffs and

rugged edges.

>> For the last few

million years, perhaps 3

million years, glaciers have

come and gone from the Rocky

Mountains. And every time they

come across the landscape,

they're capable of eroding that

landscape at rates that are

perhaps fractions of an inch

per year, meaning that over the

course of one glacial cycle you

perhaps erode 10, 20 feet

of rock.

>> Ice also created the broad

Canyons.

With every ice age, new glaciers

ground their way down v-shaped

river valleys and turned them

into broad u-shaped canyons.

>> For the glacier,

the whole valley is its

channel, so any place where the

glacier touches the wall it's

capable of eroding it.

And therefore the walls

will be made more vertical on

the edges and be flattened on

the base, until it gets

to now a u-shape which then

propagates downward.

>> Ice also explains the

presence of these boulders.

They hitchhiked at the bottom

of a glacier down the frozen

valley.

When the last ice age came to

an end and the glaciers melted

about 10,000 years ago, the

boulders were left behind.

Scientists had found two pieces

of evidence that were

responsible for the jagged

looks of the Rockies today.

A solitary boulder foreign to

the area could have only been

transported here by ice.

Striations showed scientists

that a glacier at least 1,000

feet thick covered the Rockies.

Ice was responsible for the

dramatic shape of the Rockies

today.

But the mountains keep evolving.

Recently, scientists discovered

alarming evidence that they may

collapse into a deep rift.

For the last 70 million years,

compression, erosion and ice

have sculpted the Rocky

Mountains to their present

formation.

But the geology that created

this impressive

Mountain range has also the

potential to destroy it.

Over the last 25 million years,

a gigantic rift has been

opening up at the southern end

of the Rocky Mountains.

It stretches over 160,000 square

miles and is known as the Rio

Grande Valley.

Geologists are eager to

investigate how this giant

rifting valley could affect the

future of the Rockies.

They find their first lead in

San Ysidro, New Mexico, north

of Albuquerque.

The area is dominated by

bright, yellow, porous rock

known as travertines.

Curiously, geologists think

this rock forms from water.

>> This water has some unusual

characteristics, and that is

this water's capable of

precipitating, or depositing, a

new rock called travertine. It's

kind of like the scale in your

teapot.

>> Travertine rock is

made out of calcite, the same

material that builds up lime

scale. These rocks grow very

rapidly. Some enlarge by a few

inches per month.

>> About a liter of

the water will be able to drop

out or precipitate a little

pile of calcite about as big as

an aspirin tablet.

>> Like lime scale building up

in a hot water kettle,

travertines form around warm

springs. Measurements confirm

that water temperature around

the travertines is roughly 77

degrees.

Besides the ability to build

rock, this hot water has more

secrets to tell.

Laura Crossey and Karl

Karlstrom have a hunch that the

water is warmed up by heat from

the Earth's interior, rising up

through cracks in the rock.

They form as the rift valley

pulls apart.

Climbing down a cave 25 feet

below the surface, they are

hoping to find further evidence.

The water contains microbes.

They are microscopically small

organisms.

Most of them consist of only

one cell.

When scientists analyzed their

genes in the lab, they found

something remarkable.

>> What we found in springs like

this by doing the dna analysis

is that the microbes that are

coming up these faults are much

more like what we find

at mid-ocean ridges than like

the rivers and streams we would

expect in a continental setting.

>> Mid-ocean ridges are very

long mountain chains under the

sea. Just like the rift valley,

they also form in geologically

active areas where lava

constantly erupts and builds up

new crust.

Any living organism surviving

down there has to be able to

cope with these hot conditions.

>> The springs here in the

mid-ocean ridge settings are

also characterized by

the upwelling of deep hot fluids

from within the Earth,

indicating that these both are

connected to that deep tectonic

setting.

>> The microbes suggest

deep tectonic forces are at

work, but there is even more

compelling evidence.

Karlstrom and Crossey find an

unusually high amount of gas

bubbling up through the water.

>> These samples are kind of fun

because it looks like an empty

glass bottle, but it started out

full of water. And then we

filled up--turned it upside-

down in the water, and the gas

displaced the water until it's

full of gas.

>> A lab analysis identifies the

gas as helium.

This is the conclusive evidence

that deep tectonic forces are

at work here.

>> The helium is the most

interesting gas for us. It's

the smoking gun of evidence

for where these fluids

have come from.

There's two forms of helium, but

yt's the helium 3 that we're

most interested in, and that

form of helium is only derived

from the Earth's mantle.

>> The mantle is a part of the

Earth's interior 30 miles below

the surface.

It is made up of hot, molten

rock.

In areas where magma moves up,

pressure on top of it decreases

and gases such as helium are

released.

They find their way through

faults and cracks until they

reach the surface.

So, helium gas is conclusive

proof that geological forces

deep under the Earth are

building up,

and the effect it will have on

the Rockies is devastating.

>> The Rio Grande rift

is an area that's

tectonically active

in a different way than you

think of building of mountains.

This area is the next stage

in the life sometimes of a

mountain belt where it starts to

collapse, it starts to extend.

>> As hot magma

surges upwards from 30 miles

below the surface, it forces the

area on top to spread.

The surface stretches and thins

and opens up a deep chasm.

As the rift opens, the

mountains to each side crumble

into the valley.

>> You can think of a piece

of taffy that's being stretched,

and it might break on the top.

And those breaks would lower

pieces of the--they would drop

down. And then once you have

what's called a fault valley,

then the sediments wash in from

the high mountains. It's an

immense structure. It's

about 6 miles deep. It's about

as deep as Mount Everest is

high. But when you drive

across it or you look at it

from any vantage point,

you don't see that entire depth

because it's all been filled

with sand and gravel

progressively as the extension

took place.

>> Today, the Rio Grande rift

stretches over 160,000 square

miles from Mexico in the south

where it's broadest, to

Colorado in the north where

it's only just begun to open up.

>> This rift is propagating

northwards into the higher

Colorado Rockies.

What's gonna happen to

Colorado, those mountains will

probably collapse by rifting,

as the rift propagates, zippers

northward. And you can

visualize that what's

now in Colorado is more similar

to what was in New Mexico

before the Rio Grande rift

opened and before the mountains

collapsed.

>> Looking ahead in the distant

future, there could be

challenging times.

The tectonic forces that created

the Rockies could eventually

lead to their destruction.

>> When we think

about the great continental

rifts of East African and Rio

Grande rift, the question

arises: Is the continent gonna

split apart here? If this

rifting carries on, are we gonna

have beachfront property right

here in New Mexico? And the

realtors are very interested in

this, but so are the geologists.

>> The formation of the Rocky

Mountains is a remarkable story.

70 million years ago. The death

ff ancient ammonites marked the

rise of the Rocky Mountains

from the retreating inland sea.

60 million years ago, leaves

with jagged margins grew on the

Mountains that were twice as

high as today.

10,000 years ago, a solitary

boulder marked the retreat of

the last glacier, that sculpted

the Rockies.

And helium gas in the Rio

Grande Valley today is a clue

that the area deep under the

surface is active again.

If rifting continues and the

Rio Grande Valley widens, the

area of the Rocky Mountains

could one day rip apart.

A new sea would move in, like

the vast inland sea that

covered the area 70 million

years ago.

The Rocky Mountains, the great

backbone of North America would

slowly disappear, and the

continent would once more split.

- Living proof that the Earth

is never at rest.

-- Sync, corrected by elderman -- -- for MY-SUBS.com ---