As continents shift and clash,
volcanoes erupt, glaciers grow
and recede, the Earth's crust
is carved in countless,
fascinating ways, leaving a
trail of geological mysteries
behind.
And one of the greatest is right
here, at Yellowstone National
Park in Wyoming.
This is one of the world's most
geologically active places,
shaken by up to 5,000
earthquakes every year, and
with more geysers and hot
springs than in the rest of the
world combined. Why is
Yellowstone so active? How did
it form? And why here in the
heart of the Rockies?
Scientists studying Yellowstone
are uncovering a violent past.
Carved by water, crushed by
ancient glaciers and blasted by
the biggest volcanic eruptions
ever known on the planet.
And even today, Yellowstone is
one of the most dangerous
places on Earth.
How The Earth Was Made 01x08 Yellowstone Original Air Date on March 31, 2009
== sync, corrected by elderman ==
Yellowstone National Park is one
of the most amazing places on
Earth, and it's unique.
It contains some of America's
most stunning scenery and
wildlife that attracts three
million tourists a year.
To understand where Yellowstone
came from, and why it is so
active today, we need to take a
journey back into the distant
past of the North American
continent and deep into the
Earth's interior.
Yellowstone sits 8,000 feet up
on a remote mountain plateau,
primarily within Wyoming, but
stretching into parts of Idaho
and Montana.
The park covers 3,468 square
miles, 63 miles north to south
and 54 miles east to west.
And it's on top of one of the
world's most unusual and
deadliest geological structures.
>> What's unusual about the
park? Are the wildlife unusual?
No. Is the wide open space
unusual? No. You've got it all
over the western US. What's
unusual? It's a very unusual
geology that created the park.
Yellowstone was founded as the
world's first National Park
because of the geology.
>> It's this strange geology
that attracts teams of
scientists to the park.
Their task, to piece together
the story of the incredible
processes that built this
unique, extraordinary landscape
by digging deep into
Yellowstone's past.
>> The geologic history of
Yellowstone goes back to the
formation of the North American
continent. Some of the rocks in
Yellowstone are 2.8 to 3.2
billion year old rocks, some of
the oldest in North America.
>> Only by traveling back into
the past can we figure out why
in this particular location
there are 2,400 miles of
rivers, more than 300 waterfalls
and the world's greatest
concentration of 10,000 hot
water springs, bubbling
mud-holes, gas vents and
geysers. What do these features
reveal about this landscape, and
how it was formed?
The investigation begins at
Yellowstone's star attraction,
Old Faithful.
It's a key clue to what's going
on underneath the surface.
Located in the southwest of
Yellowstone Park, the geyser
puts on an explosive display
every 90 minutes or so, blasting
out thousands of gallons of
scalding hot water.
>> Yellowstone is like no other
place on Earth, there is so
much heat coming out here.
It's really a singular
phenomenon.
Well, after about a 90-minute
nap, Old Faithful has roared
back to life. It wasn't actually
napping, it was recharging, and
the temperature of the water was
increasing, the system was
pressurizing. Beneath Old
Faithful is a rather complex
plumbing system, filled with
caverns and conduits and
constrictions.
>> Rainwater saturating the
ground around the geyser slowly
fills its underground reservoir.
Hot rocks below ground heat the
water under pressure for around
90 minutes. Suddenly, some water
spurts through a tiny, five inch
wide crack in the rocks.
This causes a drop in the
pressure within the water
chamber. In an instant,
thousands of gallons of water
are turned to steam and blasted
up into the air.
>> When the pressure builds up
enough, steam bubbles start
rising to the surface, the
system depressurizes, and a
full eruption can occur.
>> Old Faithful shows that rocks
below the surface are very hot.
Scientists find clues to a
violent past 34 miles southeast
of the hot springs, on the
shores of a circular lake
called Indian Ponds.
>> As a field geologist, my job
is to basically be a rock
detective. And so I try to
determine what their origin is
and what the history is of that
particular rock. There we go.
OK, now, in this particular
case-- Let's look at this. This
rock, when it started, it was
just a loose sand, you could
just put your fingers through
it.
>> The solid boulder is formed
from millions of individual
grains of sand.
Microscopic analysis reveals the
grains have been cemented
together by chemicals and
pressure deep under the ground.
But how did the rock get to the
surface?
Morgan has chemically dated the
rocks and discovered that 3,000
years ago, the boulder was
blasted out of the ground by
the hot water explosion of a
gigantic geyser.
>> You would see boiling water,
rock fragments and fine muddy
material being ejected up into
the air as high as 3 to 5,000
feet. And then, at some point,
material would start raining
down from this explosion column.
Now, you wouldn't want to be
standing next to one of those.
>> Indian Ponds is the crater
that the geyser left behind.
But it is dwarfed by the crater
Morgan has found at Mary Bay in
Yellowstone Lake.
Morgan has dated this geyser
explosion to 13,000 years ago.
>> So here we are in the middle
of Yellowstone Lake, and it's,
as you can see, a beautiful day
and it's nice and placid, but on
the floor of Yellowstone Lake,
it's anything but quiet.
>> Morgan's research proves that
geysers were exploding around
the lake, and even under the
water, between 13,000 and 3,000
years ago. And their size
suggests that whatever was
powering them was huge.
But is it still active today?
A clue comes from underwater
vents at the bottom of the
geyser crater.
They pump out vast quantities of
hot water and gases.
To find out what's creating the
gases, Jake Lowenstern and his
assistant collect samples from
the hot springs in the center
of the park.
The funnel they use is designed
to collect up gas bubbles
before they reach the surface,
so that they're not contaminated
by ordinary air.
>> So we let it sit for five
minutes and let the oxygen get
out?
>> Yeah.
It is a very complex mix of
gases and--but we have a--a lot
of tools that we can use to try
to unravel this rather, uh,
complicated information.
So we'll look at all of the
gases that are coming out, we
can learn about the different
kinds of rocks beneath
Yellowstone and try to
understand how things might be
changing from--from week to
week, or year to year or--or
decade to decade.
>> Analysis of the gases reveals
that they are a mix of carbon
dioxide, sulphur dioxide and
hydrogen sulphide. It is the
same mix that is found coming
out of volcanoes.
But the final clue to what's
actually going on underground
is found on the edge of the same
hot springs.
>> So these are quartz crystals
that we collected on the side
of the pool there. This stuff is
what remains. It gets tossed up,
and forms a little burr around
the side of the cr--pool and
it's all beautiful little quartz
crystals. Some of them have a
little bit of iron staining and
other things, um, but most--most
of them are--are nice, uh,
shades of yellow and--and clear.
>> Quartz crystals like these
can only have formed as a hot,
molten rock lava flow slowly
cooled after being erupted onto
the surface from deep
underground. So the crystals are
clear evidence that under the
springs is a volcano.
Yellowstone's hot water features
all point to one conclusion.
Yellowstone must be powered by
the heat of a volcano.
Geysers only erupt if the rocks
are hot enough to turn water
into steam. Gases from
underwater have the same
composition as those from
volcanoes. Quartz in the hot
springs must have come from
volcanic lava.
>> There is an immense amount of
energy coming out of the ground
that's expressed by the geysers,
the mud pots, the hot springs
and the steam vents. Where's all
that heat coming from? It's
coming from the molten rock
associated with the Yellowstone
volcano.
>> But that leaves a big
question unanswered. In this
gentle rolling landscape,
where's the volcano?
Yellowstone's unique volcanic
geology is potentially deadly
dangerous. It makes it crucial
to monitor what's happening
under the ground.
>> The Yellowstone volcano is a
very, very active volcanic
system, and so it really
requires observation.
Everything that we do here has a
research component, but it also
has a volcano monitoring
component and, uh, you know,
if--if--if activity picks up
here, we're going to want to
know something about the
plumbing system beneath us here.
>> To try and predict when
Yellowstone's hidden volcano
will erupt in the future,
scientists study its geological
past.
>> Part of our task is to look
at the landscape and read the
geologic story, and there are so
many clues and so much evidence
here to look at that it's a
fascinating place to work.
>> Scientists began
investigating Yellowstone even
before it became the world's
first national park 1872.
But observations of this
astonishing land began
long before that.
Dating ancient arrowheads shows
that Native Americans first
lived here 11,000 years ago.
Their legends of Yellowstone's
angry spirits who made the
ground tremble were passed on to
early explorers such as Lewis
and Clark.
Later reports from trappers,
explorers and mountain men like
John Colter and Jim Bridger told
of geysers that fired 70 feet
into the air and springs so hot
that meat was readily cooked in
them.
But these were thought to be
tall tales until the 1860s,
when geologists investigated and
found that the lava flows and
hot vents were signs of volcanic
activity.
But something clearly wasn't
right. Nobody could actually
find the Yellowstone volcano.
>> We say that Yellowstone is
one of the world's most active
volcanoes. People come out here,
visitors, other scientists, and
they say, "What do you mean?
I--I don't see a smoking
volcano, I don't see a big
steep volcanic, uh, uh,
crater," all the things that one
normally thinks of for an active
volcano.
>> So, without obvious signs of
a volcano, scientists hunted for
other clues.
They would find them in the
sweeping forests of Lodge Pole
pines. These are the only plants
that thrive on the poor soil
that comes from a particular
type of lava called rhyolite.
And Yellowstone's constant
plagues of mosquitoes also
reveal the presence of that same
rhyolite lava.
>> The rhyolites are--are not
very permeable, and so in--it
creates these little ponds of
water that never go away, and
those are wonderful breeding
grounds for mosquitoes. There
are a lot of mosquitoes, if you
can't see them, flying around my
head.
>> So the pine trees and the
insects both indicate that
there's a lot of rhyolite in
Yellowstone. And that's
important, because rhyolite lava
creates incredibly violent
volcanic eruptions.
>> It's much more like a bread
dough. It's about a thousand to
a million times thicker or more
viscous. If we put a bunch of
gas in it, we can have a very
explosive eruption.
>> But if rhyolite lava is that
explosive, how big a bang did
it produce?
To find that out, scientists
looked, not inside Yellowstone
Park, but in a faraway river
valley at Meadow Creek, Wyoming.
Cutting down through the land
over millions of years, the
river has exposed an unusual,
thin layer of black rock in the
cliff face.
A nearby road cutting lets
investigators examine the
mysterious, dark rock.
>> If you look at this sample,
um, in detail up close, you can
see that here's a pumice
fragment, these--these red
fragments here are--are little
rock fragments, and, uh, if we
were to make a thin section of
this rock and look at it under
the microscope, you would in
fact see compressed, uh, glass
shards.
>> The black layer that
geologists call obsidian is
actually a type of glass.
It's crucial evidence that the
rocks and soil here came out of
a volcano.
Because obsidian is forged when
boiling hot ash and gas rapidly
cool under great pressure.
And that's just what happens
when hot volcanic clouds roll
out across the landscape.
The obsidian forms in the very
bottom layers, cooled from
below and crushed by the weight
of hot debris on top.
The ash layer that crushed the
obsidian at Meadow Creek is
still visible today.
>> Its base is characterized by
this very thick, dense, obsidian
as--as the flow came to rest and
was compacted. And then, above
this dense glass layer as it
grades upwards into a tan sort
of region and continues up for
about an additional 30 feet. And
then up on top of that, as it's
exposed today, modern soil has
formed and we can see growing up
there various sorts of
vegetation, trees and grasses
and things of that sort.
>> Studying the mineral
composition of the ash proved
that it came from an ancient
volcanic blast in Yellowstone
Park.
And there's only one way that so
much ash could have been
blasted so very far away from
its source. The eruption must
have been larger, far larger,
than anything ever seen by man.
So big that scientists now label
it as a supereruption.
>> We're looking at this deposit
from a supereruption, and yet
we're over 50 miles from the
source of the--of the eruption.
>> The geologists have recreated
what must have happened here on
the day that Yellowstone
exploded. Incandescent
avalanches of ash raced out of
the park in all directions.
So this is traveling
at very high velocity, um,
easily over 100 miles per hour,
across the land surface
and obliterating everything
in its path.
It was extremely hot
when it arrived here,
and--perhaps as hot as--as
1,500 degrees Fahrenheit, two--
twice a pizza oven, I mean, it's
just very hot.
>> So what would it have been
like to be standing on this
spot hundreds of thousands of
years ago, on the day when the
Yellowstone ash cloud roared
over the horizon?
>> The--the impact of this
would--would be, uh, absolutely
unimaginable. It would be--
Yeah.
>> I think you would be
disarticulated, burned and--and!
unrecognizable, and it would be
very difficult to find any of
you.
>> All of the evidence about the
size of the supereruption
helped solve the mystery of the
missing volcano. Scientists
realized that the supereruption
was so enormous that it must
have blown the volcano to
pieces.
Swarms of mosquitoes show that
explosive rhyolite lava
underlies parts of the park.
Obsidian glass 60 miles away
reveals that ash flows spread
for miles around Yellowstone.
And thick layers of debris
confirm how gigantic an
explosion this must have been.
The problem now is the explosive
legacy that the supervolcano
left behind. Because a deadly
danger still lurks here, hidden
deep under the ground.
For nearly a century after
Yellowstone National Park was
established, nobody realized one
astonishing fact.
That the park is located inside
one of the biggest volcano
craters on Earth.
It wasn't until the late 1960s
that American geophysicist
Robert Christiansen realized
that rock formations he had
been studying for several years
all around the edges of the
park in fact formed a giant
circular ridge.
He compared his findings on the
ground with a series of NASA
pictures taken between 1966 and
1970, confirming that the ring
was the rim of a giant crater,
45 miles across.
Parts of the crater rim are
still clearly visible today,
but the other edge is almost out
of sight.
Finding the crater coincided
with another scientific
discovery in a totally different
part of the country.
In California, scientists
identified a strange, thin
layer of ash buried underneath
the modern-day soil.
The ash matched material from
the Yellowstone crater.
Dating the soil layers proved
that the ash arrived 640,000
years ago. Scientists at last
had a date for the Yellowstone
supereruption.
Ash was later found all over the
western US, confirming the huge
size of the eruption.
At least 80 times the size of
the 1883 explosion that
destroyed the island of
Krakatoa.
And 2,500 times bigger than the
1980 eruption of Mount St.
Helens.
The almost unimaginable size of
the Yellowstone blast means
that scientists now call it a
supervolcano.
But that creates another
mystery. In this peaceful
landscape, where is the steaming
hot crater that the volcano must
have left behind?
>> Today, when you're looking
out across the landscape, you
see rolling hills and--and
trees, so, obviously, there's
not a big hole left in the
ground, um, from the eruption of
the--of the Yellowstone volcano.
So something else has happened.
One of the first processes was
infilling with all sorts of
volcanic lava flows, and if you
look just down from the
landscape toward those trees,
you'll see one of the oldest
lava flows that happened after
the 640,000 year eruption.
>> Over hundreds of thousands of
years this flow has weathered
into soil and been covered with
trees.
But elsewhere in the park are a
different type of lava deposit,
still bare of vegetation because
this lava was still erupting up
until about 100,000 years ago.
The later lava was far less
explosive and more runny, and
cooled slowly.
It smoothed the harsh, volcanic
landscape into Yellowstone's
softer countryside.
That made Yellowstone, at first,
more tranquil.
But there's evidence here that
the land was soon buried once
again, this time by freezing
snow and ice.
The ice that polished the rocks,
has a story to tell.
It offers crucial evidence
about volcanic forces
still shaping the park
to this day.
Its tale unfolds through the
tiniest of clues.
Scratches on the rocks reveal
which way the ice was moving.
They show that glaciers always
slid the same way, outwards
and downwards from an icecap at
the heart of the park.
The only conclusion is that
something pushed up Yellowstone
Park so much higher than the
surrounding hills that glaciers
formed on the top.
But what force could possibly be
powerful enough to have raised
Yellowstone's peaks up into the
air?
The first clue to help answer
that question comes from
Yellowstone's numerous
earthquakes.
>> When the ground deforms, it
creaks and groans like a
Stradivarius violin. And the
creaks and groans are
essentially earthquakes.
>> The quakes are recorded by
seismometers all over the park.
>> The earthquake monitoring is
a critical part of the picture
because it's basically--it's the
stethoscope that we have to
really see and sense the--the
heartbeat of the system.
>> Smith is investigating a
puzzling geological mystery.
Yellowstone has up to 5,000
earthquakes a year, even though
it's in the stable heart of the
North American continent.
Scientists needed to know what
was happening underground to
shake the park so much.
To find out, they plotted the
precise locations and depths of
earthquakes under the ground.
So, why are there so many
quakes?
The answer had to wait until the
mid-1980s, when ever more
powerful computers first let
scientists see into the Earth.
Seismic waves spreading out from
earthquakes travel rapidly
through cold rock, but slow down
when the rocks are hot.
The varying wave speeds can be
translated by computers into
color 3D images, revealing
exactly where hot rock lies
under the ground.
>> Seismic waves propagate
through the Earth, just like
X-rays go through a body.
And so we the same physics
to reconstruct the structure
of the geology of the Earth
beneath us.
>> The seismic waves have
outlined the park's underground
structures, revealing a graphic
history of what's happened
under Yellowstone.
They reveal this gigantic
reservoir of molten rock which
created Yellowstone's crater
when lava erupted out, and the
ground above collapsed into the
space left behind.
And the seismic waves still slow
down under Yellowstone today,
showing that the magma chamber
still lurks under the park.
It's more than 30 miles long, 25
miles wide and ten miles in
depth. But its size alters from
year to year as it fills or
empties with semi-liquid rock at
an incredible 1,500 degrees
Fahrenheit. This is the hidden,
beating heart of Yellowstone
Park. The way it moves deforms
the ground above, explaining the
fault lines and the earthquakes
they produce. And its heat
ultimately powers all of
Yellowstone's hot water
pools and geysers.
Subterranean Yellowstone is
giving up its secrets.
Seismographs record thousands of
earthquakes in the park. And the
evidence of earthquake waves
reveals a massive magma
chamber miles under
Yellowstone's surface.
But the Yellowstone
investigation is far from
finished, because there's
evidence of another, even more
monstrous sized structure under
the park.
By the beginning of the 21st
century, scientists
investigating how Yellowstone
was made had images of what lay
under the park.
But there was a problem.
Technology only allowed a view
of a few miles below the
surface. Then, as more and more
data was fed into more and more
powerful computers, there was a
breakthrough.
In April 2006, geologists
published new diagrams of
hot structures, far deeper under
the park, and computers painted
more detailed pictures.
The results were startling.
Investigators saw for the first
time the sleeping monster that
lies below Yellowstone Park.
Snaking down hundreds of miles
into the Earth, far deeper than
the relatively shallow magma
chamber, is a colossal volcanic
pipe.
Nobody's certain how deep it
goes, but they can picture it
down to 400 miles or more -
twice the distance between
Washington and New York.
Smith makes an educated guess
about what the underground
plume is like.
>> Our best estimates now as we
start doing the physics and the
dynamics of these things, it's
like a conduit of melted rock,
like a chimney.
>> That chimney, called a
hotspot, pumped up enough heat
to melt the rocks of the crust
and fill the overlying magma
chamber, which then erupted to
blast out Yellowstone's vast
crater.
Understanding how the crater
formed was an important moment
for the investigation.
Because there was evidence that
similar eruptions had happened
before. Many times before.
Throughout the 1960s, various
teams of geologists studied the
Snake River Plain, to the
southwest of Yellowstone Park,
and found traces of ancient
volcanic craters.
The crater rims had long been
eroded, but their outlines were
confirmed by aerial pictures
over the following decade.
They ran in a straight line
along the plain, heading for the
heart of Yellowstone Park. On
average, each crater was a
couple of million years older
than its neighbor.
Investigators realized that
these are the remnants of
earlier supervolcano explosions,
an unbroken chain stretching far
back into geological history.
It seemed clear that, time after
time, the hotspohad blasted
out a supereruption and then
moved on. The hotspot appeared
to have traveled hundreds of
miles.
But that posed yet another
riddle. How could a hotspot
anchored to the core of the
planet be moving?
An important clue had been found
in 1985 by American
volcanologist William Scott.
He realized that plotting the
location of 30,000 earthquakes
around Yellowstone produced an
amazing pattern.
The quakes traced out a giant
V-shape on the surface of the
Earth.
The V-shape wrapped around
the hotspot's location. It
seemed, at first, to confirm
that the hotspot was still
moving, rippling up the land
around it with fault lines and
tens of thousands of
earthquakes.
But the real answer lay with the
theory of plate tectonics. It
showed that it's the American
continent, not the hotspot,
that's moving.
And the chain of craters on
Snake River Plain is there
because for millions of years,
the moving American continent
has continually pushed new land
over the stationary hotspot.
But, as the North
American Plate moved across this
source of heat, it pops through
the lid and creates the hotspot
track. That's the Snake River
Plain. Yellowstone is just the
active component today.
>> The repeated hotspot
explosions on land have made
Yellowstone unique.
Other hotspots have been
identified around the world,
like the one that has created
the island chain of Hawaii, but
Yellowstone is the only place
where a hotspot has erupted in
the middle of a continent.
Each of the earlier explosions
blew the original mountains to
pieces. Then, the land smoothed
over with later flows of more
runny lava that was released
from deep under the Earth's
crust.
Multiple strands of evidence
combine to reveal Yellowstone's
slumbering monster, the gigantic
hotspot plume lying under the
park. Earthquake maps show the
hotspot's location.
Seismic waves reveal the depth
of the plume.
And earlier craters prove
regular supereruptions over
millions of years. All of which
leads to the most frightening
question of all. When will
Yellowstone erupt again?
Measuring the amount and
geographical spread of ashfall
from Yellowstone's
supereruptions produced some
terrifying figures.
640,000 years ago, the eruption
poured out around 240 cubic
miles of material - enough to
bury the whole of New York
State tens of feet deep in ash.
If it happens again, thousands
will die and vast areas of the
United States will be buried in
volcanic debris. But when will
Yellowstone erupt again?
One clue to when that next
eruption will happen comes from
investigating the eruptions of
the past.
The hotspot punches out a
supereruption, on average,
every 600,000 years.
And the last one was 640,000
years ago.
But geologists expect that there
will be warning signs before
Yellowstone explodes again.
Volcanic eruptions are usually
preceded by an increasing
number of earthquakes.
The quakes are a sign that
underground volcanic chambers
are filling with molten rock and
expanding to stretch and deform
the land up above.
Yellowstone Park usually
experiences an average of 12
tiny earthquake tremors every
day. Most are too weak to be
felt by tourists and register
only on the most sensitive
seismometers. But in early 2009,
more than four times as many
quakes started striking every
day. Over one ten-day period,
there were more than 500
quakes, some of them up to
magnitude 3.9, powerful enough
to frighten the visitors and put
the scientists on alert.
There's a second indicator of
increasing volcanic activity.
If more molten rock does inflate
the underground chamber, the
ground above will rise.
And that, too, seems to be
happening right now.
Unusual evidence to prove it
comes from an unlikely source,
the waters of Yellowstone Lake.
Around 100 years ago, small
steamships carried tourists on
sightseeing trips across the
lake. But one of the ships
caught fire and sank forever
below the surface of the lake.
But now, Yellowstone's
astonishing geological forces
have resurrected the ship's
remains from their watery grave.
>> Here we have a boat which
burnt down to water level and
so this tells us something about
the deformation of Yellowstone,
and basically, what's happened
is that the floor of the lake
has risen, bringing the boat out
of water.
>> The reappearance of the wreck
shows that land under and
around the lake is rising
because of the expansion of the
magma chamber.
>> Even more alarmingly, the
rate at which it's rising seems
to be increasing. In geological
terms, a huge area of
Yellowstone Park is
positively soaring up into the
air, faster than it's ever done
before.
The biggest uplift of all has
been recorded just a few miles
from the shore of the lake.
There's a GPS system here,
a much more sophisticated
version of the one in your car.
It measures not only its surface
position, but also its exact
altitude to within fractions of
an inch.
>> There's a small radio
antenna, about the size of your
thumb, that sits on top of this
steel rod, and it is anchored in
two to thr--about three or four
feet, so if the ground moves up
and down, the antenna moves up
and down.
>> The GPS and the land on which
it's anchored are moving
upwards.
>> We're above the magma chamber
and, beginning in late 2006,
this whole area of ground
started to rise, uh, at the
order of two to three inches per
year. And as of today, this
whole system right here has
risen about that much, and it's
still moving today, and so we're
measuring and keeping close
track of the deformation,
the--of the uplift that we're
seeing at this station.
>> But does the uplift mean that
Yellowstone's supervolcano is
threatening to erupt once again?
>> The question of what lies in
Yellowstone's geologic future
is fascinating, and I and all of
my colleagues would love to
know the answer to that
question.
>> The scientists keep a careful
watch on the volcano's activity.
>> The idea of science is to
understand the process and so
we have a responsibility to see
how this system is deforming,
and how it's working, hence we
have to be aware there is still
a possibility of--of volcanic
eruptions or earthquakes. After
all, that's what made this
system, and, uh, there is no
reason to think that volcanism
has stopped.
>> The Yellowstone investigation
has shown that the park's
sleeping supervolcano is still
alive, and dangerous.
Old Faithful's underground
plumbing reveals volcanic heat.
Obsidian glass tells of a
massive eruption. Seismographs
record thousands of earthquakes,
while the earthquake waves
reveal terrifying underground
chambers. And the reappearance
of a sunken boat shows that the
land is rising.
And yet, the ultimate
Yellowstone geological question
remains to be answered. When
will the supervolcano erupt once
again?
We know there's
enough magma left, we know
there's enough heat, we know
that there will be future
eruptions in Yellowstone. But we
don't know if there will ever be
another catastrophic eruption.
>> So the investigation is left
with a deadly serious warning.
On the timescale that geologists
work to, a coming supereruption
in Yellowstone may well be right
around the corner. That corner
could be 10,000 or 100,000 years
in the future. Or it could be
tomorrow. A new and devastating
chapter in the ever-changing
story of how the Earth was made.
== sync, corrected by elderman ==