>> 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 addic7ed.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 addic7ed.com ---