All language subtitles for Modern.Marvels.S23E04.Rocks.Greatest.Hits.1080p.WEB-DL.DDP2.0.H264-BTN_track3_[eng]

- [Narrator] They are
the powerful engine

of the Earth's energy.

- If you fell in there,
you could get boiled alive.

- [Narrator] They support
the tallest skyscrapers

and are the foundation for
over 40 million miles of roads.

- [Man] All of
construction has been

based on using crushed stones,

from the early Roman roads
to today's interstates.

[dramatic music]

- [Narrator] Whether they're
billions of years old

or as young as this morning,

they hold the secrets
of the universe.

- [Sarah] There's no way
to put a price on them.

- [Narrator] You'll never think
of that pebble in your shoe

the same way again.

Now get ready to rock,

on "Modern Marvels:
Rock's Greatest Hits."

[dramatic music]

[rock music]

Rocks,

they may be the most
underappreciated objects

in the natural world.

But we'd be stone cold
out of luck without them.

Besides providing
us with shelter,

we extract metal from rocks
to construct our machines.

- Whether you're sitting
in a chair made of steel

or you're driving a
car made of steel,

that steel came from rocks.

- [Narrator] We take heat
from them for warmth,

and precious minerals
to make medicine.

- We rely on rocks to
make soil, to grow plants.

- [Narrator] At one time,
we used them for weapons.

They season our food,

and add sparkle and
wealth to our lives.

- If you're operating a
computer, the silicon chips

that make up an important
part of that computer

come from rocks.

- [Narrator] The Earth is
one huge ball of rock,

25,000 miles around and
over 4.5 billion years old.

But a question, what are the
most valuable rocks on Earth?

They very well may be NASA's
collection of lunar rocks

located at the Lyndon Johnson
Space Center near Houston.

[upbeat music]

They're housed in a special
building at the center

which was constructed
to quarantine astronauts

and material brought
back from the Moon

during the Apollo missions.

The lab is off limits
to the general public,

and those who work
here must observe

stringent cleanliness protocols

to protect the rocks from any
form of earth contamination.

All workers who come in
contact with the rocks

must wear a bunny suit.

- The suit that I'm wearing
is a nylon clean room suit.

The air that comes into this
lab is filtered very well

with very, very
small HEPA filters,

so the air stays very clean.

Well, this is the
door to the vault

where we keep our
lunar samples safe.

This is equivalent to a
federal reserve bank vault,

and it's a very, very
secure kind of storage.

This is a very substantial
door, as you will see.

And inside here,

we keep the samples
that are still pristine.

We originally brought
back 842 pounds.

And you can see, we
have cabinets in here,

and these cabinets have nitrogen
gas running through them.

- [Narrator] The nitrogen
protects the rocks

from certain elements in
the Earth's atmosphere.

- On the Moon there is no
oxygen and there is no water.

The minute the lunar samples
were to come in contact

with oxygen or water
in our atmosphere,

they would begin to oxidize.

Or in simple terms, they
would begin to rust.

And the samples,
in a few decades,

wouldn't be any good
for scientific study.

- [Narrator] Collecting these
geological samples from the Moon

was a top priority of
the Apollo Missions.

No better clues exist about how
the Moon formed and evolved.

To gather the Moon rocks,

the astronauts came equipped
with custom designed tools.

- These are tongs.

They worked by
squeezing the handle

and the tongs would open,

and this enabled the astronauts
to pick up rocks off the ground,

because they really couldn't
bend over in their space suits.

- [Narrator] Some of the rocks

the astronauts brought
back from the Moon

were similar to
those found on Earth.

Many were basalt, a product
of volcanic activity.

- [Gary] There were lavas
and there were crustal rocks,

like the kinds of rocks we
made granite tombstones out of.

- [Narrator] As the crewman

gathered the rocks
on the lunar surface,

other rocks, tiny ones,
hurtling through space,

added an element of
danger to their mission.

Such rocky debris,
including meteorites,

also pelts the Earth,

but Earth's atmosphere protects
us by disintegrating them

or slowing them down.

The Moon, which
has no atmosphere,

exposed the astronauts
to the threat.

- [Gary] They come in
at such fast speeds,

many times the
speed of a bullet,

and the space suits
were made in such a way

that they could withstand
some of these impacts,

because this mass of these
particles is very small.

[astronaut murmuring
indistinctly]

- [Narrator] Despite the danger,

none of the Apollo astronauts
were injured by the particles.

- [Astronaut] Beautiful,
just beautiful.

- [Narrator] Back on Earth,

scientists believe that the
rocks recovered from the Moon

posed an entirely
different kind of threat.

- We were concerned that
perhaps there were bugs

or some sort of Andromeda strain

that might exist on the Moon,

but it was a very
rare possibility.

We understood that the
radiation environment

and the lack of an
atmosphere on the Moon

would make it very difficult
for a life to survive.

But you always wanna be cautious
in an unknown environment.

- [Narrator] Extensive
tests determined

that the Moon rocks contain
no hint of alien life.

But as hoped,

they have helped researchers
gain many new insights.

Since basalt is a common rock
on both the Moon and on Earth,

studying its chemistry
was the basis

for a mind-boggling theory on
how the Moon itself was formed

over 4.5 billion years ago.

- The leading theory right now
for the formation of the Moon

is that very early in
solar system history,

a planet or a proto
planet the size of Mars

impacted the very
early planet Earth.

The Mars-sized
planet was shattered.

The core of that Mars-sized
body became part of Earth,

and the exterior parts,
the crust and the mantle,

were all pulverized,

and all those particles went
into orbit around the Earth.

So for a while, the
Earth had a ring system.

And then over time,

those particles began to
slow down and coalesce.

And after a while,

they had all clumped up,
and they became the Moon.

- [Narrator] But what about the
six sextillion tons of rock

we call planet Earth?

By the way, that's almost
800 billion tons of rock

for every person on the planet.

What are they?

In simple terms,

rocks are composed of
one or more minerals.

Minerals are the most solid
material found on Earth

and they always have the
same chemical makeup.

There are three basic
classifications of rock.

One is igneous,
like the rocks found

in the lava fields of
the Hawaiian Islands.

- An igneous rock is a rock
that's formed from cooled magma,

magma being liquid molten rock
that has come to the surface

or near the surface, like
you would see in a volcano.

- [Narrator] Another type
of rock is sedimentary,

like that found in
the Grand Canyon.

- Sedimentary rocks
are formed by erosion

making bigger rocks
into smaller rocks.

And these smaller rocks,

when they lay on top each
other over many, many years,

they cement together until
they form a solid rock,

a sedimentary rock.

- [Narrator] The third type
of rock is metamorphic.

Metamorphic rock forms

when a preexisting rock
type is subjected to heat

and extreme pressure.

This causes a physical or
chemical change in the rock.

- It could be an igneous
rock, originally,

sedimentary rock originally,
or another metamorphic rock.

The word metamorphic, meta
means change, morph means form.

So in some fashion
has changed in form,

either through a change
in the mineralogy

or the hardness of the rock.

- [Narrator] It can take
millions of years

for a rock to morph from
one form to another.

Yet in our never ending
drive to put rocks to use,

we're speeding up the
process with technology.

Sometimes we can almost
do the impossible.

You ever hear the
phrase, sink like a rock?

Well with today's technology,
we can reverse that.

- We get some products that
actually weigh less than water,

they'll actually float
when you put them in water.

- [Narrator] This is
lightweight aggregate,

but you won't find it in nature.

This rock has been manufactured
at the Stalite Company

in Gold Hill, North Carolina.

[upbeat music]

Composed of sand, gravel
and crushed stone,

aggregate is a primary
ingredient in concrete.

Without concrete, we wouldn't
lay foundations strong enough

for buildings to scrape the sky,

or build titanic dams,
or pave the sidewalks

leading to our homes.

However, all aggregates
are not created equal.

[upbeat music]

Lightweight aggregate
composed of such light,

but strong rocks
is meta-argelite,

can make much lighter
weight concrete

than traditional aggregate.

And lightweight
concrete is desirable

because it can reduce
construction costs.

- Lightweight aggregate reduces
the weight of the concrete

by 25 to 30%, which allows you
to use a lot less foundation,

less reinforcement,
less reinforcing steels,

and there's less seismic mass
of the foundations as well.

[rock music]

- The rocks that the
Stalite Company uses

to produce the
lightweight aggregate

come from North Carolina's
Gold Hill Quarry,

operated by the Vulcan
Materials Company.

- This is our meta-argelite.

It is not a slate actually,
but it has a slatey appearance.

It's very hard.

- [Narrator] This rock
is so hard,

it has to be blasted
out of the ground.

The explosive used is
made of ammonium nitrate,

an ingredient also found
in yard fertilizers.

The explosives are
placed in a pattern

that will create a domino
effect when detonated.

- These holes are
approximately 46 feet deep.

We drill on a 15
by 17 foot pattern.

[machine whirring]

This is a booster.

Inside the booster
will go a cap.

The cap is a non-electric cap.

It is set off by a powder
substance inside the tube.

[ground explodes]

The amount of rock
that's blasted can vary,

but here we usually get about
30,000 tons out of a shot.

- [Narrator] First stop for
these rocks, the rock crusher.

- The rock is dumped
onto a feeder.

This feeder is fastened to
a set of something called

grizzly bars, and
they are like grates

with openings between them.

These things will
feed the rock forward.

It allows the smaller
rock to fall out

and not go through
the primary crusher,

therefore saving energy.

- [Narrator] /Up to 7,000 tons
of rock are crushed each day.

That's the weight of a
fleet of almost 4,000

mid-sized automobiles.

[rock music]

After crushing, the rocks
tumble through several screens

to be sorted,

and are then sent
to a rotary kiln.

The kiln is where modern
alchemy turns heavy rock

into light.

For it is here that the rock
material expands under heat

without losing strength.

- And as it slowly
tumbles through the kiln,

the temperature
slowly rises up to

about 2,100 degrees Fahrenheit.

And at 2,100 degrees,

the material is actually
starting to soften.

And then the gases inside,

basically sulfur dioxide
and some other gases, form,

and they try to escape.

And what they do is
they create millions

of little non-connected cells,

millions of little air bubbles

that are entrapped
inside the aggregate.

Then the material falls
and goes through the cooler

and it hardens.

That's how it gets
its low weight,

because none of the cells
are actually connected,

but there's millions of them
entrapped inside the aggregate.

- [Narrator] Stalite then
sells the cooled aggregate

to construction firms
all over the world

to make lightweight concrete

used in skyscrapers, bridges,

and other major
construction projects.

One type of rock dominates
our city landscapes.

Carved from nature's majesty,

and to finely cut
building blocks

of countless classic structures,

[jackhammer buzzes]

granite is synonymous with
hardness and durability.

You can count on it to last,

from the facade of the
Empire State Building

to your glistening
kitchen countertop.

And it all comes from quarries,

like the Rock Of Ages
in Barre, Vermont.

Over 500 feet deep,

the quarry is one of the
largest in the world,

noted for both the
quality of its rock

and the extent of a deposit.

- Barre stone itself is
just an exceptional granite,

probably the finest gray
granite yet discovered

anywhere in the world.

The deposit's been measured
by sound technology.

It's approximately
four miles long,

one and a half to
two miles wide,

and it's estimated to be up to
about 10 miles in thickness.

- [Narrator] That's a
tower of granite,

the height of over 36
Empire State buildings.

The deposit at the Rock Of Ages,

like all granite,
is igneous rock.

It formed from magma generated
millions of years ago

by friction between tectonic
plates deep below the surface.

Less dense than the solid
rocks surrounding it,

the molten material rose
up through the cracks

in the overlying rock and cooled

into the huge granite deposit.

Granite from the Rock of
Ages Quarry has been used

in many of America's greatest
buildings and monuments.

- We were very, very
proud to be a part

of the fabrication of the
national World War II Memorial

on the mall in Washington, D.C.

The steps of the capital
building in Washington, D.C.,

are also fabricated
from Barre Gray granite.

- [Narrator] Rocks such
as granite and marble

are often used as
so-called dimension stones.

- The term dimension
stone refers to stone

that's cut to be a
certain dimensional size,

rather than aggregate that's
to be used for crushed stone

and other purposes.

[rock music]

- [Narrator] Often it's
taken out of the ground

in giant blocks, weighing
as much as 200 tons.

Because granite is so hard,

it takes giant powerful drills
and saws to cut into it.

Quarrymen call the
process of separating

the granite into
blocks, channeling.

To separate a block
from the quarry wall,

they first have to
cut around the sides

and the back of the block.

One method uses a slot drill.

- A slot drill is an
air driven rotary drill.

It is set up so that it
drills a vertical hole

up to about 20 feet in depth.

Then the drill rod
retracts automatically,

moves over on a
tracking mechanism.

We sink another hole in another

until we have a row of closely
spaced holes up one side,

across the back, and
down the other side.

- [Narrator] Once workers drill
these initial sets of holes,

they make another
pass at the rock,

drilling out the granite
between the holes,

called the web.

[rock music]

But now comes the hard part.

They've gotta
separate the bottom

without destroying
the equipment.

The process is
called undercutting.

It begins by drilling
a series of holes

in the bottom of the block

and will end with
a huge explosion.

- We use primer cord
that's often used as a fuse

in other industries.

Looks like a giant jump rope.

It's on a large
reel, like a wire.

It's reamed into the
holes with a metal rod

about every other hole.

Then it's tied
together electrically

and set off remotely.

- Fire.

[ground explodes]

- [Narrator] Once loosened
the slabs are lifted

to the rim of the quarry by
giant derricks, or cranes.

The most powerful of the
derricks can lift an astounding

200 tons of stone at a time out
of the 500 foot deep quarry.

- We lower a cable from a
derrick and put it in a loop

around the perimeter
of the stone.

We don't go
underneath the stone,

because we would have
no way of lifting it up

to put the cable underneath it.

So we go around the perimeter,

actually cut a small notch
into each of the four corners

of the stone, and draw
the cable tightly,

just like a slip knot, so
that the harder that the block

pulls on the cable,
the tighter it becomes.

- [Narrator] Next, the granite
goes to a processing plant

to be cut and polished.

This is where workers craft
it into the dimension stones

used for our
buildings and homes.

[upbeat music]

The most unusual place
the granite might show up

is six feet over your head.

Craftsmen first workout
tombstone design and lettering

on a computer.

- Then that design is
transferred from paper

to a rubber sheet
by the computer.

[mallet pounding]

The rubber sheet is then
temporarily adhered, or glued,

to the surface of the granite,

and parts of it are cut
away to form a stencil.

- [Narrator] A sand
blaster then takes over,

spewing its abrasive
under high pressure

at 125 pounds per square inch.

Even granite gives way
under this assault.

- The abrasive actually
will hit the rubber,

but because it can absorb
some of the energy,

it deflects and it bounces away.

- [Narrator] Well, granite
earns its reputation

as a tough and versatile
player above and below ground.

Some rocks are in demand for
their durability and beauty.

It's been a favorite of
artists and architects

for centuries, whether
used in great works of art,

like Michelangelo's
statue of David,

or classic buildings, like
the United States Capital

and the Lincoln Memorial.

Marble is one of the most
sought after materials

on the planet, and
built a global industry

worth more than $50 billion.

- Marble is such
a desirable stone

because it unifies two
very important things:

the beauty and the strength.

[upbeat music]

- [Narrator] Most marble
quarries are above ground,

but the Vermont Marble
Company's mine in Danby, Vermont

is the largest underground
marble quarry in the world.

Their marble supply here
reaches over one mile

into the Earth and is
spread over 25 acres.

Marble is a metaphoric rock
formed by the alteration

of limestone, or dolomite.

[machines whirring]

It's so hard, they use
diamond wire saws to cut it.

Diamonds are the
hardest of all rocks,

and one of the few strong
enough to cut through marble.

The diamonds are strung
on a flexible wire.

- We put it on a
certain sequence,

and we start with a spring,

and we slide it on the cable,

and then we use a spacer,

and then we use a pearl,

what we call pearl, because
it's round and it's expensive,

and it's got diamonds.

And we do another
spacer, a spring,

spacer,

a pearl.

- [Narrator] When the diamond
saws blur into motion,

the workers keep their distance
in case the wire breaks.

- It's very dangerous work.

We have to be careful
where you're standing,

because when the wire breaks
you could get hit with pieces

coming off the wire moving
at a high rate of speed.

- [Narrator] The workers select

only the highest grade of stone.

- What you're looking at here

is the face of the
gallery side area.

And that black, and
gray, and brown streak

you see in there is what
we call tunnel rock.

It's not the desirable
stuff that we're after.

This is actually the
stuff that we desire.

This particular block
right here is what we call

an imperial marble.

It's some of the finest
marble in the world.

[upbeat music]

- [Narrator] Pure white
marble is the result

of the metamorphism of
very pure limestone.

When mineral impurities are
present in the limestone,

they can produce the
characteristic swirls and veins

in many varieties
of colored marble.

[rock music]

Blocks sliced from the
wall can weigh as much

as 1,000 metric tons, and
are worth about $10,000

before being processed.

Workers cut them down
to about 45,000 pounds

to make them more
manageable during transport

to the processing plant.

It too is underground.

Here the marble is cut
to the exact dimensions

specified by customers.

Then it is sent to the polisher.

- It has 14 different
heads on it,

and it has different
abrasives that are put

on to the head, and then
the marbles fed through

on a conveyor, and
the heads come down,

and each one does its part.

And when it comes
out the other side,

you can either have
what you call a honed

or a glassy finish.

[relaxed music]

- In the past, the quarry
stone has been ordered

for both the Jefferson Memorial

and the United
States Supreme Court.

[upbeat music]

Yet another type of rock
holds the precious stuff

industry uses to
make everything,

from your car, to your
appliances, to your paper clips.

But prying it loose requires
a lot of water, heat,

- Fire!
and noise.

[ground explodes]

Our modern world is built
on a foundation of iron.

Mined in 50 countries
for its durability,

iron makes up approximately
95% of all metals used today.

- Iron is used to make steel.

We would not have all of the
factories, the appliances,

the cars.

None of the things that we know
today in modern civilization

would exist basically
without iron and iron ore.

- [Narrator] And iron comes
from rock like this.

When a rock is valuable enough
to be mined for the metals

or minerals trapped
within it's called ore.

Minnesota is one of the
most iron rich states.

- Minnesota was blessed
with a large deposit of iron

called the Biwabic
Iron Formation,

and it extends for about
110 miles long from Babbit,

Minnesota down to Grand
Rapids, Minnesota.

- The iron ore began forming
over 2 billion years ago,

when the area
that's now Minnesota

was covered by a shallow sea.

- The iron source was located

to the north of the iron range,

and was from volcanic
material that was deposited

into a water filled basin,

and later buried, and heated

and formed into a hard
iron formation rock.

- [Narrator] Since the
late 19th century,

more than 4 billion tons
of ore have been mined

from the Biwabic Formation.

- Iron mining began in 1892

near the town of
Mountain Iron, Minnesota.

Then from that point
on, more and more mining

came into a place.

The initial mines
were underground.

They later turned
into open pit mines.

- The most valuable iron ore,

during the days of Minnesota
mining, was hematite,

which is nearly 60% iron.

Within six decades, miners
had exhausted the rich supply.

- It went through World
War I, World War II.

Vast quantities of iron ore
were mined to provide steel

for the battleships,
and the tanks,

and everything else
that went along

with those two war efforts.

And in the process, of course,

a lot of the natural iron ore,

the stuff that you could
just mine out of the ground,

was exhausted.

So in the early 1950s, a
new process was developed

called the taconite process.

- [Narrator] With about
22% iron content,

taconite ore is nowhere
near as rich as hematite,

which could be loaded directly
from the ground into steel,

making blast furnaces.

[rock music]

With taconite, the iron
content must be extracted

grain by grain, and
then concentrated.

Key to the process is
taconite's magnetic qualities.

- An important characteristic
of the taconite

that's being mined is
that the iron is magnetic,

and it can be separated from
the non-magnetic material

very easily through
magnetic separation.

To illustrate that point,

I'll hold a magnet on to
the black material here,

and you'll see that it sticks.

The white material, which
is quartz, is non-magnetic,

and the magnet falls off.

- [Narrator] The process
of magnetic separation

begins by blasting the stone
from out of the ground.

The procedure is
similar to that used

for blasting aggregate loose.

- Four, three, two,
one, zero, fire.

[ground explodes]

- Large haul trucks
carry the blasted rock

to a processing plant.

- This is where we
take the blasted ore,

We dump it into this crusher.

It's a giant, gyrating
cone that slowly turns.

And as it turns, it crushes
the ore against the side wall,

reduces it in size from
this blasted material

down to about minus six inches.

[rock music]

- [Narrator] From here,
the process involves

reducing rocks to
smaller and smaller bits

so the magnetic iron
can be extracted.

From the crusher, the rocks
go through a series of mills

inside the processing plant.

- So the first stage of
grinding is called the rod mill.

And what we do there
is we introduce

the crushed ore with water
and put it into a slurry form,

which is just a mixture of
water with the ground material.

All of our processing
is done wet.

So we have to mix water with
whatever material we have

to transport it
through the process.

And then we feed it
into these large mills

that rotate and tumble.

Inside of these mills, we put
large diameter grinding rods.

These are about four inches
in diameter and 20 feet long.

And as these rods tumble over
with the turning of the mill,

they grind the ore
into a finer slurry.

- [Narrator] Then the slurry
goes through its first set

of magnetic separators,

which attract particles with
at least 100 times more power

than the magnet on your
refrigerator at home.

- Magnetic separators
are large rotating drums

that have permanent
magnets inside of them.

The magnetic portion
of the ground material

is then picked up and separated

from the non-magnetic portion.

- [Narrator] The particles are
then sent to ball mills.

They grind them down to the
consistency of face powder.

- We use one and a half inch
diameter grinding balls,

which are fed into the mill.

And as they tumble, they
grind the ore even finer.

- [Narrator] Not ready yet,

the material then goes
through another set

of magnetic separators.

It emerges as a concentrate
of about 67% iron.

- At that point in time,

we then start adding some
limestone and dolomite

back into the process to
make a very special pellet

for our customer.

[upbeat music]

- [Narrator] These pellets are
the form in which the iron

will be fed into
the blast furnaces.

At first, the concentrate
must be dried.

- In that plant, we
use vacuum disc dryers

to actually suck the moisture
out of this wet concentrate.

- [Narrator] An air blast
loosens the particles.

- That concentrate is
then fed into what we call

balling discs.

And we spin these discs,
and we create these pellets,

which we call green balls.

- [Narrator] Then the pellets
are baked in a giant furnace.

- And this is a long,
260 foot furnace

where the pellets are fired
at 2,400 degrees Fahrenheit,

and then cooled down as
they exit the process.

The pellets have to be
hardened to a certain strength

in order for them to
withstand the transportation

that occurs between here
and the blast furnace.

- [Narrator] The pellets
are now over 60% iron.

- When the pellets come
off the end of the furnace,

they're quite hot yet.

And when they enter into
the stockpile behind us,

they're still at a couple
of hundred degrees.

From here, the pellets
are loaded into rail cars

and shipped down to a
port on Lake Superior.

From there, the pellets
are loaded into boats,

where they begin their journey
down to the blast furnaces

at the Southern end
of Lake Michigan.

- [Narrator] In the
blast furnaces,

the pellets are melted
into molten iron.

[rock sizzling]

Some furnaces using the pellets

can produce over 10,000
tons of molten iron a day.

From here, the molten
iron will go to foundries

where the steel is made
to build our world.

As rocks rich with iron
demand a complex process

to extract their treasure,

another kind of invaluable
rock comes pre-fabricated

by nature.

[rock music]

When it comes to rocks, bigger
doesn't always mean better.

The smallest rocks of
all, sand and gravel,

are crucial ingredients
in construction projects

requiring asphalt or concrete.

- Typically asphalt is in the
range of 95% stone products.

Concrete is about 80%.

For a single family home,
it's about 400 tons of stone.

- [Narrator] It's estimated
that 38,000 tons of aggregate

are necessary to
construct one mile

of a four lane
interstate highway.

[upbeat music]

Crushed rock, sand, and gravel,
and lightweight aggregate

have been essential building
materials since ancient times.

- From a historical
perspective, you look back,

basically all of
construction has been based

on using crushed stone, sand
and gravel type products,

from the early Roman roads
to today's interstates.

Basically our nation
and our economy

are based on a solid foundation
of construction aggregates.

- [Narrator] Unlike
rock quarries,

where we rely on explosives
to blast the aggregate loose,

[ground explodes]

the deposits in many
sand and gravel quarries

come ready made
by mother nature.

They're situated where
the loose rock has existed

since prehistoric times,

like here in Prince
George County, Virginia.

About a hundred
million years ago,

a river ran through this area,

leaving layers of
rock along its shores.

- Weathering breaks
the rocks down

into various size fractions.

As they're moved along
the river channels,

they are rounded and broken
into smaller and smaller sizes.

- [Narrator] With each
passing century.

The river deposited
more and more layers

of loose sand and gravel.

- The excavator's
loading material

that's not been blasted,

it's a loose material that
we can dig quite easily.

- [Narrator] Sand is
composed of rocks,

such as feldspar,
limestone and quartz.

Gravel consists of pebbles,
stones and fragments

of such minerals as
shale and granite.

- We mine the sand and gravel

with a 5.6 yard cubic excavator.

Our haul truck's are 40
ton articulated trucks.

On a good day, we can average
between eight and 10,000 tons

with this operation.

We haul the material
to the surge pile,

dozer pushes it over,

and a loader picks it up and
puts it into the feed hopper.

- [Narrator] The feed hopper
distributes the sand and gravel

onto a huge conveyor belt

that transports it to the
main processing plant.

- With the price of
diesel fuel going up,

we didn't want to have to
haul the material over a mile,

so we installed almost
a mile of conveyor belt

that will carry approximately
a thousand tons an hour.

- [Narrator] At the
processing plant,

a vibrating machine with a
series of sifting screens

separates the sand
from the gravel.

- Once the material hits
the number one screen,

that material is then sized

according to whether
it goes into the gravel

or the sand circuit.

- [Narrator] Each of the
screens has a smaller mesh

than the one above it.

The larger gravel
rocks stay at the top,

and the smaller sand
particles drop to the bottom.

- That begins a process of
sorting the material by size.

It's essentially like this.

[sand pours]

[can rattling]

The material goes
across the first screen,

and then goes through a
series of additional screens

and is sorted by size
in decreasing diameter.

- [Narrator] Once separated
from the gravel,

the sand is sent through an
additional screening process

in water filled
classifying tanks.

Much like panning for gold,

the finer sand particles rise

to the top of the
water separator,

and the heavier ones
drop to the bottom.

- This is a finer sand that
we pull out our core sand.

We then take this material,

let it go by gravity back
down to the ground level,

pump it back up again, and
resize it even further.

- [Narrator] After processing,

the sand and gravel are
ready to be shipped.

The construction aggregate
business is so competitive

that shipping costs
are a major concern.

Therefore, most
quarries are located

close to construction
site areas.

- Construction aggregates
are typically used

within 20 to 30 miles or
their point of production.

- That is unless there
are no local suppliers.

Then the material will have to
be shipped longer distances.

In this case, a barge
is the likely transport.

- This pit is adjacent
to the Appomattox River,

we ship quite a bit
of our material on barges

down to the Norfolk area.

Finished product is loaded on
our barge load aid facility

here behind me.

Dump trucks dump it
in a grizzly hopper

up the conveyor
belt onto the barge.

This barge will hold
approximately 2,000 tons.

[rock music]

- [Narrator] The aggregate
is often shipped

to concrete plants,

and then sent off to make
our churches, swimming pools,

and shopping malls.

Although rocks are most
useful as building materials,

they may soon rock our world
in a surprising new way.

In fact, we're starting
to light up our cities

with an endless power source,
not so deep beneath our feet.

The world is looking for
sources of clean, reliable,

and renewable energy.

Northern California
has found it.

- We're in the
Mayacamas Mountains

of California's coast range

at the Geysers power plants.

The Geysers power plants
are geothermal power plants

that cover 40 square miles
of the mountains here

and generate enough
electricity to provide 850,000

households with electric power.

- It's the largest
geothermal area,

for it's producing
power, in the world.

- [Narrator] And where does this
geothermal energy come from?

Hot rocks.

In most places,
molten rock or magma

exists very deep in the Earth,

where temperatures
are extremely high.

The Geysers area is
unique in that the magma

is very close to
the Earth's surface.

- The heat that supplies
the Geysers is supplied

from liquid magma
about five miles deep,

this liquid magma
that was left over

from a volcanic period
that existed here

about 1.3 million years ago.

That volcanism is
long since gone,

but it's left behind
these pools of magma.

- [Narrator] In some
of the geysers,

this heat bubbles right
up to the surface.

- This is a steam vent,
also known as a fumeral,

and it's evidence
that we're very close

to a geothermal resource here.

Steam exits that
vent at 250 degrees,

causing that water to boil.

If you fell in there, you
could get boiled alive.

- [Narrator] The owners of
the Calpine Corporation

operate most of the
Geyser power plants,

but they aren't the first
ones to take advantage

of this unique place.

- This area was known to the
Indians thousands of years ago

when they lived here.

They utilized the hot
Springs for hot steam

and for hot water.

Later on, in about 1847,

an Explorer named
William Bell Elliot

happened on this area and
was really quite surprised

to see steam venting
out of the ground

and hot bubbling mud coming up.

And so he returned
to his companions

exclaiming that he'd
found the gates of hell.

- [Narrator] During the 1920s,
several attempts were made

to tap the geothermal
energy resources here

for electrical power.

But it wasn't until the 1950s

that drilling technology
became advanced enough

to make the resource
truly productive.

- As they started
drilling thermal wells

deep into the Earth's
core to capture the steam

and utilize it to
generate power.

From there, in the sixties,
the first plant was built.

And since then they've
built up to 23 plants

that have operated up
here in the Geysers

almost for 50 years.

- [Narrator] The wells at the
Geysers don't have to reach

all the way down to
the liquid magma,

but only to where the
rocks are hot enough

and there is enough water to
create a large supply of steam.

Nevertheless, many of
the wells are drilled

over two miles into the ground

until they reach sandstone.

- The sandstone's been heated,

and it has water in
that turned into steam.

But on top of that sandstone
is what's called a cap rock.

And that cap rock holds all
that heat and steam pressure

down in the rock.

We drill down through that
cap rock and into what we call

a geothermal reservoir.

And that reservoir
is highly fractured,

so there's cracks and
fishers that allow that steam

to travel, essentially,
through the rock

and then into our well, or pipe.

- [Narrator] The drilling
equipment is identical

to that used for
oil and gas wells.

- This kind of drilling
that we're in right now,

we're in hard rock
drilling, very deep.

We use these tungsten
carbide bits here.

These are the
cutting edges here.

It's very, very hard.

It wears
very, very long time.

- Once drilled, the
steam is channeled

into an intricate
network of pipelines,

stretching over a hundred miles.

- This is a
geothermal well head,

connected to a steam well

that extends two
miles underground.

The steam exits this well head
at 350 degrees Fahrenheit,

and the steam's transported
down the pipeline

at 70 miles an hour
to the power plant.

- [Narrator] The pipe itself
originates from rock material,

primarily iron ore.

- Pipes made out of iron,

when an iron gets
hot, it expands.

When the iron starts out cold,
when it's first installed,

it might only be 35, 40
degrees here at the Geysers.

And this is 350
degrees right here,

so the pipe has to be allowed
to expand and contract.

And that's why
everything is mounted

on these little shoes like this.

It gives us some leeway,
when it gets hot and cold,

to slide back and forth.

- [Narrator] The steam is
piped to giant turbines.

[upbeat music]

This power is then
transferred to a generator.

- That generator is
generating 50 megawatts

of electricity right now,
enough to power 50,000 homes.

- [Narrator] The
electricity is then sent

all over Northern California.

Then it's time for the
water to pay another visit

to the hot rocks.

- What you see behind me here

is the power plant
cooling tower.

After the steam has expended
its energy in the turbine,

it's condensed and sent out
here to the cooling tower

to be cooled where it could be
injected back into the ground

to produce more steam.

What you see coming out of
the top of the cooling tower

is not smoke.

It's just pure water
vapor that's being cooled

through evaporation.

- We have an endless
supply of energy

in which we can generate power.

This is renewable energy
that works around the clock.

The geothermal power comes
up naturally 24 hours a day,

seven days a week.

- [Narrator] Across the
globe, many countries

are looking to the
heat of hot rocks

for future energy needs.

- The potential for
geothermal energy is huge.

The Earth has an inexhaustible
supply of energy.

Worldwide, geothermal
energy is produced

in about 20 different countries.

- [Narrator] In the areas
of the world where steam

isn't as close to the surface

as it is at the Geysers,

engineers are experimenting
with a process

called hot dry rock technology.

- In hot dry rock
geothermal technology,

there's no steam locked
up in the hot rock

that exists down
under the crust.

So what engineers
have tried to do

is drill down into that rock,

and then, taking
whatever water source

they happen to have
available at the surface,

pump it down into a well,

let it work its way out
into the cracks and fishers

in that hot, dry rock,

and then drill more wells
around the perimeter,

and try to recover
that water as steam

to produce electricity.

- [Narrator] The wills
have to be deeper

with hot rock technology.

But theoretically, the process
could produce enough energy

to supply the entire
world's demands.

Not bad for a bunch of rocks.

Whether they're creating
energy for our homes,

iron for our industries,

or concrete for
our infrastructure.

Rocks partner with
us in stony silence.

They've stood by us in the past,

and they will
support our future.

Rock on.