NARRATOR: They're in
every skyscraper we erect and every road we pave. Rocks are the
beginning of everything. NARRATOR: The indispensable
ingredients of the mundane and the monumental. It's some of the finest
marble in the world. NARRATOR: Some can even float,
while others can supply us with unlimited power. This is renewable energy
that works around the clock. NARRATOR: Billions of years old
or as young as this morning, they hold the secrets
of the universe. Fire. [explosion] NARRATOR: Now, rocks
on "Modern Marvels." [music playing] 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. They're priceless because
we can't bring any more back until we have a new
system to get back to the moon. So there's no way to
put a price on them. NARRATOR: 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 building where we keep
the rocks was specially designed to hold them. It can withstand a Category
5 hurricane, or a tornado, or almost any other natural
event that you could think of. NARRATOR: 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 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. GUY LOFGREN: There were lavas. And there were crustal rocks,
like the kinds or rocks we make granite tombstones out of. NARRATOR: As the crewmen
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. GUY LOFGREN: 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 the mass of these
particles is very small. NARRATOR: Despite the danger,
none of the Apollo astronauts were injured by the particles. Back on Earth, scientists
believed 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 life to
survive, but you always want to be cautious in
an unknown environment. NARRATOR: Extensive tests
determined that the moon rocks contained 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 protoplanet
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
6 sextillion tons of rock we call planet Earth? By the way, that's about
1 trillion 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 of each other over many, many years,
they cement together until they form a solid
rock of sedimentary rock. NARRATOR: The third type
of rock is metamorphic. Metamorphic rock forms when
a pre-existing 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, it
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 term
"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. Composed of sand, gravel,
and crushed stone, aggregate is a primary
ingredient in concrete. Without it, concrete
wouldn't exist, and neither would the
modern world as we know it. We couldn'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. Lightweight aggregate composed
of such light but strong rock as meta-argillite 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 steel. And there's less size and mass
of the foundations as well. NARRATOR: 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-argillite. It is not a slate, actually,
but it has a slate-y 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. Ammonium nitrate is
essentially the same fertilizer that you put on your
yard to make it go. NARRATOR: 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. Here's 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. [explosion] 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 midsize automobiles. GUY MEDLIN: We have a
primary jaw crusher. It's capable of doing
about 1,000 tons an hour. The operation is much like a
jaw or a crankshaft on a motor. NARRATOR: 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,
it becomes pyroclastic, so that means 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 trapped
inside the aggregate. And the material falls and goes
to 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
trapped 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. Another kind of rock looms
large as a building block of modern civilization. The slabs that workers
carve from massive quarries like this one will end up in
everything from your kitchen to your crypt. One type of rock dominates
our city landscapes, carved from nature's majesty
into finely cut building blocks of countless classic structures. 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 the 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 4 miles
long, 1 and 1/2 to 2 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 Earth's surface. Less dense than the solid
rock surrounding it, the molten material
rose up through 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 that is now on the
mall in Washington DC. The steps of the Capitol
Building in Washington DC are also fabricated
from Barre gray granite. NARRATOR: Rock 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. 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. Quarry men 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, and 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. But now comes the hard part. They've got to separate the
bottom without destroying their 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. It'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! [explosion] 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 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 slipknot, 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. The most unusual place
that granite might show up is 6 feet over your head. Craftsmen first work out
tombstone design and lettering on a computer. Then that design is
transferred from paper to a rubber sheet
by the computer. 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: Another stone
that stands the test of time is marble. Whether used in
great works of art, like Michelangelo's statue of
David, or classic buildings, like the United States Capitol
or the Lincoln Memorial, it's been a favorite of artists
and architects for centuries. Marble is such a desirable
stone because it unifies two very important things-- the beauty and the strength. 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. The marble supply here reaches
over 1 mile into the earth and is spread over 25 acres. Marble is a metamorphic rock
formed by the alteration of limestone or dolomite. 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. Then we use a spacer. And then we use a pearl,
what we call a pearl, because it's round,
and it's expensive, and it's got diamonds. Then we do another spacer,
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. You've got 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. 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. 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 onto the head. And then the marble's 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 they call a honed or a glassy finish. NARRATOR: In the past,
the quarry's stone has been ordered for both
the Jefferson Memorial and the United
States Supreme Court. Yet another type of rock holds
the precious stuff industry uses to make everything from
your car to your appliances to your paperclips. But prying it loose
requires a lot of noise-- Fire! [explosion] NARRATOR: --water and heat. Our modern world is built
on a foundation of iron. 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, its called ore. Minnesota is one of the
most iron-rich states. Minnesota was blessed with
a large deposit of iron called the Biwabik Iron Formation. And it extends for
about 110 miles long from Babbitt, Minnesota, down
to Grand Rapids, Minnesota. NARRATOR: 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's 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, 4 billion tons of ore have been mined from
the Biwabik Formation. Iron mining began
in 1892 near the town of Mountain Iron, Minnesota. Then from that point
on, more and more mining came into place. The initial mines
were underground. They later turned
into open pit mines. NARRATOR: The most valuable
iron ore during the early 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. 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 onto the black material here. And you will 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. 4, 3, 2, 1, 0. Fire. [explosion] NARRATOR: 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 6 inches. NARRATOR: From here, the process
involves reducing the 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 that grind them
down to the consistency of face powder. We use 1 and 1/2 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. NARRATOR: These pellets are
the form in which the iron will be fed into the blast furnaces. But 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. 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 prefabricated by nature. Grab your toys-- it's
time to play in a sandbox. 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 1 mile of a four-lane
interstate highway. 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, 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 at Vulcan Materials
Puddledock Quarry in Prince George County, Virginia. About 100 million years ago,
a river ran through this area, leaving layers of
rock along its shores. Weathering breaks rock down
into various sized 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. The haul trucks are
40-ton articulated trucks. On a good day, we can average
between 8,000 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
1,000 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
rock 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. 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 the finer sand that
we pull out of our coarse sand. We then take this material,
let it go by gravity back down to the ground level, pump
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
of their point of production. NARRATOR: 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, and we ship quite a
bit of our material on barges down to
the Norfolk area. Finished product is
loaded on our barge load out 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. NARRATOR: The aggregate is
often shipped to concrete plants and then set 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. We're starting to
light up our cities with the power of hot rocks
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 as far as 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 5 miles deep. This liquid magma was left over
from a volcanic period that existed here about
1.3 million years ago. That volcanism has
long since gone, but it's left behind
these pools of magma. NARRATOR: In some
areas of The Geysers, this heat bubbles right
up to the surface. This is a steam vent,
also known as the fumarole. 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
Geysers' 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 Elliott
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. 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 '60s
the first plant was built. And since then,
they have 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 2 miles into the ground
until they reach sandstone. The sandstone's been
heated, and it has water in it 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 if there's cracks and
fissures that allow that steam to travel essentially
through the rock, and then into our well 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 works a very, very long time. NARRATOR: Once
drilled, the steam is channeled into an intricate
network of pipelines stretching over 100 miles. This is a geothermal
wellhead connected to a steam well that extends 2
miles underground. The steam exits this wellhead
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
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. This power is then
transferred to a generator. That generator's 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 expanded
its energy in the turbine, its 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 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 is 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 fissures
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 wells have to
be deeper with hot dry 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.
