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KIRK JOHNSON:
North America,
the land that we love.
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It looks pretty familiar,
don't you think?
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Well, think again!
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The ground we walk on
is full of surprises...
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if you know where to look.
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As a geologist,
the Grand Canyon is perhaps
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the best place in the world.
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Every single one of these layers
tells its own story
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about what North America
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was like when that layer
was deposited.
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So are you ready
for a little time traveling?
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I'm Kirk Johnson,
the director
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of the Smithsonian National
Museum of Natural History.
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And I'm taking off
on the field trip of a lifetime.
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Look at that rock there--
that is crazy.
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In this episode:
North America is locked
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behind an enormous wall of ice.
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How did the first humans
to ever set foot
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on the continent
manage to get in?
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This is not the easiest thing
in the world.
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Once they got here,
the challenges were daunting.
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(trumpeting)
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But somehow, we turn the rocks
of our homeland...
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Oh, man!
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...into riches.
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This thing is phenomenal.
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But what challenges lie ahead?
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Because our continent
may be hiding
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some pretty dangerous secrets.
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"Making North America: Human,"
right now, on
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NOVA.
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Major funding for
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NOVA
is provided by the following:
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gleaming cities.
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The incredible wealth
of our land,
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supporting a population
of over half a billion.
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But rewind the clock
just 15,000 years
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and our continent
was truly a wild kingdom
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filled with amazing
Ice Age creatures.
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(roaring)
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Still, there was one animal
found nearly everywhere
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but here... us.
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So how, in the blink
of a geologic eye,
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did we turn
an unpopulated continent
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into a rich and dynamic
civilization?
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And what surprises does our
homeland still hold in store?
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The story of humans in
North America begins with ice.
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Alaska's Mendenhall Glacier,
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a 13-mile-long expanse
thousands of feet thick.
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This particular ice
has been here for centuries.
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It may not be as old as rock,
but for a geologist,
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it's no less intriguing...
if a bit risky.
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Just a bad place to trip.
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Yeah, I guess there's
that, isn't there?
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Yeah.
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Once you start falling
on this ice
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you keep falling until
you hit something flat.
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JOHNSON:
15,000 years ago,
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this is what much of
North America looked like.
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By then, humans had migrated
from Africa to Europe,
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Asia, and Australia.
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Not yet to the Americas,
but that was about to change.
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North America
was in the grip of an ice age.
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So much of the world's water
was locked up in ice sheets
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that sea levels dropped,
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exposing a thousand-mile-wide
expanse of land
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that connected Siberia to
Alaska, the Bering Land Bridge.
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In the summer, this would have
been a huge, open expanse,
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allowing ancient
hunter-gatherers from Siberia
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to migrate east
into North America.
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But the open landscape
abruptly ended
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at the edge of a vast ice sheet
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in what is now
southeastern Alaska.
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Would they have tried
to cross it?
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Ready for this?
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I think so.
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All right,
here we go.
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A little bit higher
and to your right
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and you should be good.
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That's it, yup.
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This is not the easiest thing
in the world.
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(breathless):
You know, it's hard to imagine
somebody crossing
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even one ice field like this,
much less an entire ice sheet.
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This is insane.
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Glaciers are perilous,
ever-shifting
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and often unstable.
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Early explorers would have had
a tough time getting very far.
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Imagine trying to cross
big ice sheets
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100 miles wide,
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couple thousand feet high,
into North America.
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Based on this,
I'm pretty sure the people,
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if they came into North America
at that time,
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didn't go over the ice.
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MAN:
Looking good, buddy!
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JOHNSON:
So how did the first Americans
wind up on the other side
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of this daunting barrier?
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The traditional view is that
when climate began to warm
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about 13,000 years ago,
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melting along a seam between
two great inland ice sheets
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opened a corridor.
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But there's another
potential route
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to the rich land beyond the ice,
first hinted at
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by a discovery made over
1,000 miles to the south
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off the coast of California.
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25 miles from Santa Barbara
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lie the remote and windswept
Channel Islands.
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Here on Santa Rosa Island,
a little over 50 years ago,
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a lone archaeologist
stumbled upon
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some of the very earliest
human remains
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ever found in North America.
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Joining me is Joe Watkins,
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a National Park Service
anthropologist
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and a member of the
Native American Choctaw tribe.
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He's taking me to a spot
that has tremendous meaning
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to Native peoples
and scientists alike.
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This is a very
important place;
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it's what brings us
to Santa Rosa Island.
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Well, that's a nice
bluff right there.
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Yeah.
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JOHNSON:
Right here in an area called
Arlington Springs back in 1959,
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archaeologist Phil Orr spotted
a couple of distinctive bones
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revealed in the weathered cliff.
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Joe has a replica.
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It's clearly a thighbone.
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There's the knee joint
and there should be
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a ball on the...
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Here it is.
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That fits on...
that fits on right there.
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So I've got a thighbone
of a human.
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Exactly, and there were
two femurs that came out.
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They come from a man about
five-foot-one-inches tall.
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But it's the age
that has put
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the prehistory
of North America on its ear.
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JOHNSON:
Named Arlington Man,
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these bones date
to around 13,000 years ago.
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They're among the oldest human
remains ever to be discovered
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in North America.
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More than 13,000 years ago
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puts these bones
during the last ice age.
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Exactly.
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And that's what makes them
significant.
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JOHNSON:
Significant because not only
was Arlington Man
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one of the earliest known
inhabitants of North America,
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but he lived and died here
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on an island
miles off the coast.
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WATKINS:
That means that Arlington Man--
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or his ancestors--
probably got here by boat.
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That's an amazing fact.
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They didn't walk here,
they paddled here.
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If boats were in use here,
then they were probably in use
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all along the coastline,
from Alaska to South America.
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They may have been similar
to traditional Inuit boats--
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wooden frames
covered with walrus hides--
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agile and rugged vessels.
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This kind of technology
could have opened a way south
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even before the ice sheets
melted.
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WATKINS:
If you figure boats
into the equation,
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it really opens up a whole
different set of possibilities.
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You don't have to go
through the ice,
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you can just paddle down
the coastline.
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JOHNSON:
Using boats to probe the shore
could have opened the way
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for seafaring hunters
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to settle along the western edge
of the continent.
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And as they made their way
into this unexplored land,
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what untapped riches
would they have found?
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Luckily for us,
there are a wealth of clues
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in the unique geology
of Southern California...
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...extracted over the years from
an iconic tourist attraction,
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the La Brea Tar Pits.
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This is one of the greatest
fossil sites in the world,
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and it's right
in the middle of Los Angeles.
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Shallow pools of natural sticky
asphalt have been bubbling up
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from below the surface here
for tens of thousands of years,
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creating a lethal trap
for unsuspecting animals
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and a perfect graveyard
for their bones.
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Hey, Carrie, how's it going?
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Hi, Kirk, how are you?
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JOHNSON:
Carrie Howard
is a paleontologist
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working with an incredible trove
of animal fossils
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all pulled from the pits.
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What these bones tell us
is that this area
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was once a great
hunting ground--
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and not just for ancient people.
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Wow, that's a nice skull.
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Oh, yeah, this is
a saber tooth cat skull.
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It sure is!
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(laughs)
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As you can tell.
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It would have stabbed
or sliced its prey.
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In one, in,
boom you're done.
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Wow, so think about that,
just about the time that
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people showed up in North
America for the first time,
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these guys were waiting
to greet them.
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(laughing):
A bad day in California.
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More than a million bones
have been found here
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in the last century--
the largest, from huge mammoths
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that weighed
up to 12,000 pounds.
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All told, something like 620
different species
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of plants and animals
have been identified.
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Bison scapulae.
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Horse neck vertebrae.
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More bison leg bones.
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These are really great.
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Wow, look at those things,
that's a huge animal.
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Big camel vertebra.
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Wow.
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Toes of camels and more camels,
and more camels!
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There are a lot
of camels here.
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HOWARD:
Yeah, not many people know
camels originated
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in North America.
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JOHNSON:
It's so amazing to hear
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there were camels
here in Los Angeles.
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00:12:17,500 --> 00:12:18,900
(trumpeting)
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For ice age hunters,
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00:12:20,766 --> 00:12:24,266
the mammoth would have been
especially valued,
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each one providing
thousands of pounds of meat--
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if you could bring it down.
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What kind of weapon
could have evened the odds?
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To track down an answer,
I head to Boulder, Colorado.
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00:12:45,066 --> 00:12:48,500
A few years ago, Patrick Mahaffy
was having
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00:12:48,600 --> 00:12:50,766
some landscape work done
behind his house.
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One day, when he checked in
with the work crew,
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he got an unexpected report.
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PATRICK MAHAFFY:
I got home from work.
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00:12:58,733 --> 00:13:00,200
It was a very busy day for them,
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00:13:00,300 --> 00:13:02,100
and I asked, you know,
like you do on a project,
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"How did the day go?"
and they went through this list
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00:13:04,233 --> 00:13:05,766
of all the things
that they'd done.
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00:13:05,866 --> 00:13:08,133
And then they said,
"Oh, and there's one last thing.
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We found something."
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JOHNSON:
They found what seemed to be
an intentionally buried cache
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of mysteriously shaped stones.
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DOUG BAMFORTH:
That one's amazing.
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00:13:26,766 --> 00:13:29,300
That is amazing.
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00:13:29,400 --> 00:13:32,766
JOHNSON:
Archaeologist Doug Bamforth
was called in to take a look.
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00:13:35,800 --> 00:13:38,600
I regularly get phone calls
about people's discoveries.
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But I don't get very excited,
because they usually
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don't turn into
much of anything.
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But then I went up the next day
and it was just breathtaking.
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JOHNSON:
An 83-piece stone age tool kit,
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each piece
carved by ancient hands.
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BAMFORTH:
There's a good sharp edge.
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00:13:56,033 --> 00:13:58,233
You could only hold it between
the tips of your fingers,
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but you could do light cutting.
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00:14:00,900 --> 00:14:04,733
JOHNSON:
13,000 years ago,
these sharpened stones
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00:14:04,833 --> 00:14:06,200
would have been
the most advanced technology
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00:14:06,300 --> 00:14:07,933
on the continent.
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00:14:08,033 --> 00:14:11,400
BAMFORTH:
You have to imagine a world
with no metal in it.
249
00:14:11,500 --> 00:14:15,000
All the things that we rely on
to cut things and scrape things
250
00:14:15,100 --> 00:14:17,500
and do almost all
of our physical work, right,
251
00:14:17,600 --> 00:14:19,333
the fundamental material
that we use,
252
00:14:19,433 --> 00:14:21,000
did not exist in the world.
253
00:14:22,733 --> 00:14:25,500
JOHNSON:
Like other early human
societies,
254
00:14:25,600 --> 00:14:29,233
North Americans relied on stone.
255
00:14:29,333 --> 00:14:32,266
So Doug wanted to know
how old were the tools
256
00:14:32,366 --> 00:14:34,200
in this collection?
257
00:14:36,833 --> 00:14:40,266
To find out, Doug decided
to test for DNA residue
258
00:14:40,366 --> 00:14:43,000
that might give him a clue
about the age.
259
00:14:46,200 --> 00:14:49,066
Incredibly,
he found traces of blood
260
00:14:49,166 --> 00:14:52,733
from several species of animals.
261
00:14:52,833 --> 00:14:55,700
Two in particular surprised him.
262
00:14:55,800 --> 00:14:58,266
He found DNA from the ancestors
263
00:14:58,366 --> 00:15:01,700
of modern-day
horses and camels--
264
00:15:01,800 --> 00:15:04,166
species that once lived
in North America
265
00:15:04,266 --> 00:15:07,033
around the end of the Ice Age,
266
00:15:07,133 --> 00:15:09,266
clear evidence that these tools
were once used
267
00:15:09,366 --> 00:15:11,333
by some of
the earliest American hunters.
268
00:15:13,566 --> 00:15:15,700
BAMFORTH:
Getting artifacts that have
blood residue on them
269
00:15:15,800 --> 00:15:18,600
from camels and horses tells us
270
00:15:18,700 --> 00:15:20,666
that these are among the oldest
tools we know about
271
00:15:20,766 --> 00:15:21,933
in North America.
272
00:15:23,200 --> 00:15:25,100
So evidence of some of the very
earliest people who were here.
273
00:15:27,866 --> 00:15:31,800
JOHNSON:
The most lethal hunting weapon
they devised was a spear tip
274
00:15:31,900 --> 00:15:35,066
known as a Clovis point,
named after the site
275
00:15:35,166 --> 00:15:38,566
where it was first discovered
in New Mexico.
276
00:15:38,666 --> 00:15:41,833
Clovis points all share
a common design:
277
00:15:41,933 --> 00:15:45,933
a symmetrical, fluted shape
with sharp edges on both faces.
278
00:15:47,866 --> 00:15:50,966
More than 4,000 Clovis points
have been found
279
00:15:51,066 --> 00:15:53,433
all across North America,
280
00:15:53,533 --> 00:15:58,233
a sign that the first Americans
traded weapons-grade rock
281
00:15:58,333 --> 00:16:00,200
and the latest hunting
technology
282
00:16:00,300 --> 00:16:02,700
over hundreds of miles.
283
00:16:06,100 --> 00:16:08,900
Bob Patten has been crafting
Clovis point replicas
284
00:16:09,000 --> 00:16:12,100
for over 40 years,
and he's offered to show me
285
00:16:12,200 --> 00:16:16,333
just how tricky it can be
to coax a sharp-edged weapon
286
00:16:16,433 --> 00:16:17,833
from a stone.
287
00:16:19,266 --> 00:16:20,366
BOB PATTEN:
These are antler.
288
00:16:20,466 --> 00:16:21,933
Oh, I see.
289
00:16:22,033 --> 00:16:23,233
That catches the blow.
290
00:16:23,333 --> 00:16:25,866
And I want you to reach
forward a little bit.
291
00:16:26,700 --> 00:16:28,466
There you go.
292
00:16:28,566 --> 00:16:29,366
Wow, my first flake!
293
00:16:29,466 --> 00:16:31,733
Awesome!
294
00:16:31,833 --> 00:16:34,666
JOHNSON:
We're using a rock called chert.
295
00:16:34,766 --> 00:16:39,066
It's similar to flint and was
favored by stone age toolmakers
296
00:16:39,166 --> 00:16:41,500
because of a very special
property:
297
00:16:41,600 --> 00:16:44,666
with a bit of persuasion,
the rock will break off
298
00:16:44,766 --> 00:16:47,566
razor-sharp flakes.
299
00:16:47,666 --> 00:16:49,700
PATTEN:
This is better
than an X-Acto knife.
300
00:16:49,800 --> 00:16:53,166
Wow, you're cutting
leather with a rock.
301
00:16:53,266 --> 00:16:55,000
You can cut with
great precision there, too.
302
00:16:57,666 --> 00:16:59,000
I can see the spear point
in there,
303
00:16:59,100 --> 00:17:00,566
I just can't quite get
to it yet.
304
00:17:00,666 --> 00:17:04,633
JOHNSON:
Bob's going to put the finishing
touches on my Clovis point.
305
00:17:04,733 --> 00:17:08,166
He seems to have a knack
for finding just the right spot
306
00:17:08,266 --> 00:17:09,933
to hit the stone.
307
00:17:10,033 --> 00:17:12,166
It's a very subtle thing,
308
00:17:12,266 --> 00:17:13,733
and you have to train yourself
309
00:17:13,833 --> 00:17:15,566
in order to do this
consistently.
310
00:17:17,500 --> 00:17:20,000
Now we've got a tool
we can go hunt a mammoth with.
311
00:17:20,099 --> 00:17:22,433
Oh, you'd put it
on something fairly long
312
00:17:22,533 --> 00:17:24,366
because a mammoth
is a big animal
313
00:17:24,466 --> 00:17:27,200
that you don't want to get
too close to until he's dead.
314
00:17:27,300 --> 00:17:31,466
JOHNSON:
It's hard to imagine
how a relatively small stone
315
00:17:31,566 --> 00:17:34,266
could bring down an animal
the size of an elephant.
316
00:17:35,766 --> 00:17:37,833
To test its killing power,
317
00:17:37,933 --> 00:17:40,733
I'm going to use
a block of ballistics gel.
318
00:17:42,233 --> 00:17:45,033
It's a material
used to test firearms,
319
00:17:45,133 --> 00:17:49,066
because it has
the same consistency as flesh.
320
00:17:50,333 --> 00:17:52,833
You've got the mammoth,
I've got the spear.
321
00:17:52,933 --> 00:17:56,633
JOHNSON:
A piece of animal hide covers
the front of the ballistics gel,
322
00:17:56,733 --> 00:17:58,300
so I'll be able to see how well
323
00:17:58,400 --> 00:18:01,666
the spear point
penetrates skin, too.
324
00:18:01,766 --> 00:18:05,233
All right,
so the angle is here.
325
00:18:05,333 --> 00:18:07,166
It's like shooting
a pool cue.
326
00:18:10,366 --> 00:18:11,233
And now.
327
00:18:15,700 --> 00:18:16,800
The blade went in
328
00:18:16,900 --> 00:18:19,100
like it was going
into a block of butter,
329
00:18:19,200 --> 00:18:21,400
and when it hit the actual shaft
that's when it stopped.
330
00:18:21,500 --> 00:18:23,100
Well, I think we know
331
00:18:23,200 --> 00:18:24,866
why that style of point
was so successful.
332
00:18:24,966 --> 00:18:25,966
Yeah, that thing
really worked.
333
00:18:26,066 --> 00:18:28,066
It does cut.
334
00:18:28,166 --> 00:18:31,566
And we should be ready to go
and conquer the continent.
335
00:18:33,266 --> 00:18:36,833
JOHNSON:
Clovis points have been found
embedded within the bones
336
00:18:36,933 --> 00:18:40,900
of mammoths, demonstrating
just how successful
337
00:18:41,000 --> 00:18:42,833
these weapons could be
in bringing down
338
00:18:42,933 --> 00:18:44,833
even the biggest beasts.
339
00:18:48,500 --> 00:18:51,700
These Clovis spearheads
are exquisite artifacts,
340
00:18:51,800 --> 00:18:54,033
just beautiful things to behold.
341
00:18:54,133 --> 00:18:56,900
But in reality they were
lethal killing machines.
342
00:18:59,066 --> 00:19:05,633
By 12,000 years ago, mammoths,
saber-toothed cats, dire wolves,
343
00:19:05,733 --> 00:19:11,733
camels and many other large
mammals had all but disappeared,
344
00:19:11,833 --> 00:19:15,900
likely the victims
of an expanding human population
345
00:19:16,000 --> 00:19:16,866
and a changing climate.
346
00:19:19,400 --> 00:19:22,500
But others thrived
on a landscape that offered
347
00:19:22,600 --> 00:19:26,066
more than a million square miles
of grass-covered prairie--
348
00:19:26,166 --> 00:19:28,466
home to a North American icon.
349
00:19:31,966 --> 00:19:34,933
WATKINS:
On the Great Plains,
these oceans of grasses
350
00:19:35,033 --> 00:19:37,866
were the primary food
for millions of bison.
351
00:19:41,233 --> 00:19:43,100
These bison were the supermarket
on the hoofs
352
00:19:43,200 --> 00:19:47,766
for the nomadic Native American
tribes that hunted them.
353
00:19:47,866 --> 00:19:51,000
The bison hides could be used
for housing.
354
00:19:51,100 --> 00:19:53,800
They made them into teepees
that could be put up
355
00:19:53,900 --> 00:19:56,033
and taken down
in a matter of minutes,
356
00:19:56,133 --> 00:19:59,333
just so that the Native American
tribes could follow the herds
357
00:19:59,433 --> 00:20:01,300
from one spot to the next.
358
00:20:01,400 --> 00:20:05,733
For 10,000 years,
this was their staple food.
359
00:20:09,566 --> 00:20:12,133
JOHNSON:
The geology of North America
created a landscape
360
00:20:12,233 --> 00:20:15,800
ideally suited to support
abundant animal life,
361
00:20:15,900 --> 00:20:17,733
sustaining a growing
human population.
362
00:20:19,833 --> 00:20:22,733
But not all Native Americans
hunted for a living.
363
00:20:27,266 --> 00:20:31,466
In Colorado's Mesa Verde
National Park,
364
00:20:31,566 --> 00:20:34,866
I've come to see a genuine
wonder of the ancient world.
365
00:20:37,433 --> 00:20:40,666
Tucked away in these
rocky hills
366
00:20:40,766 --> 00:20:46,466
stands an 800-year-old
architectural masterpiece
367
00:20:46,566 --> 00:20:47,900
called Cliff Palace.
368
00:20:55,466 --> 00:20:58,000
(laughing):
Oh man, that
is so awesome.
369
00:21:02,733 --> 00:21:06,000
Built from finely laid
sandstone slabs,
370
00:21:06,100 --> 00:21:09,800
pine beams and mortar
beneath natural overhangs,
371
00:21:09,900 --> 00:21:16,566
this 150-room complex was home
to the ancient Puebloans,
372
00:21:16,666 --> 00:21:19,266
forbearers of today's
Puebloan peoples.
373
00:21:23,200 --> 00:21:25,433
This is a massive set
of structures here.
374
00:21:28,833 --> 00:21:31,066
So these were a people that
really invested in real estate.
375
00:21:31,166 --> 00:21:32,533
SCOTT TRAVIS (laughing):
Yeah.
376
00:21:32,633 --> 00:21:36,166
JOHNSON:
Scott Travis is the park
archaeologist.
377
00:21:37,700 --> 00:21:40,133
It's characteristic
of cliff dwellings at Mesa Verde
378
00:21:40,233 --> 00:21:43,033
to have this type of scale,
but nothing approaches
379
00:21:43,133 --> 00:21:45,633
the sheer size
of this particular site.
380
00:21:45,733 --> 00:21:49,233
JOHNSON:
And this original cavelike
structure is a natural formation
381
00:21:49,333 --> 00:21:50,666
in the sandstone.
382
00:21:50,766 --> 00:21:52,566
TRAVIS:
It's just a natural part
of the evolution
383
00:21:52,666 --> 00:21:54,266
of these canyon systems.
384
00:21:54,366 --> 00:21:58,566
JOHNSON:
These formations--
along with others like them--
385
00:21:58,666 --> 00:22:01,866
provided shelter for thousands.
386
00:22:01,966 --> 00:22:04,233
And for centuries,
387
00:22:04,333 --> 00:22:06,300
the people here
worked the land as farmers,
388
00:22:06,400 --> 00:22:09,066
even though conditions
were often tough.
389
00:22:10,533 --> 00:22:13,766
TRAVIS:
Mesa Verde is a wonderful
example of how
390
00:22:13,866 --> 00:22:15,566
the Ancestral Puebloans
took advantage
391
00:22:15,666 --> 00:22:17,066
of their local situation.
392
00:22:17,166 --> 00:22:19,666
Not only did they create
remarkable architecture
393
00:22:19,766 --> 00:22:22,133
within the alcoves,
they were able to farm
394
00:22:22,233 --> 00:22:25,466
in one of the harshest
environments on this continent.
395
00:22:25,566 --> 00:22:26,533
(thunder)
396
00:22:28,733 --> 00:22:31,566
They did this with a combination
of expert geological knowledge
397
00:22:31,666 --> 00:22:36,033
and the ability to control
scarce water resources
398
00:22:36,133 --> 00:22:39,500
to farm in a situation
that is difficult even today.
399
00:22:43,266 --> 00:22:46,300
JOHNSON:
And other farming cultures
did even better,
400
00:22:46,400 --> 00:22:48,733
using their resource wealth
to build big cities
401
00:22:48,833 --> 00:22:50,666
and giant places of worship.
402
00:22:52,700 --> 00:22:55,600
Like the builders
of the mysterious mounds
403
00:22:55,700 --> 00:22:57,900
at Cahokia, Illinois,
404
00:22:58,000 --> 00:23:01,700
who raised corn
to support a city of 15,000.
405
00:23:04,066 --> 00:23:07,900
Or the Maya of Central America,
who built canals
406
00:23:08,000 --> 00:23:11,666
and irrigation networks that
sustained great stone cities.
407
00:23:13,533 --> 00:23:17,466
Hundreds of thousands
lived in the Aztec capital
408
00:23:17,566 --> 00:23:20,233
in Central Mexico at the end
of the 15th century.
409
00:23:23,366 --> 00:23:25,333
But the story of human
interaction with the geology
410
00:23:25,433 --> 00:23:27,633
of North America was about to be
turned on its head
411
00:23:27,733 --> 00:23:30,566
by the arrival of outsiders.
412
00:23:34,066 --> 00:23:37,166
Western European explorers
opened the way for conquerors,
413
00:23:37,266 --> 00:23:41,266
colonists, and their slaves,
who would all ultimately
414
00:23:41,366 --> 00:23:43,300
displace most of
the Native population.
415
00:23:45,133 --> 00:23:50,300
What drew so many to voyage
so far into an unknown world?
416
00:23:54,033 --> 00:23:58,200
To find out, I'm traveling
to North Carolina
417
00:23:58,300 --> 00:24:01,766
to a research station
that studies a native plant
418
00:24:01,866 --> 00:24:05,400
that enticed European settlers
with a promise of riches.
419
00:24:05,500 --> 00:24:06,800
It's pretty cool.
420
00:24:06,900 --> 00:24:09,166
I have never been in
a tobacco field before.
421
00:24:09,266 --> 00:24:11,100
This is the plant that got
North America started
422
00:24:11,200 --> 00:24:12,566
as a Btish colony.
423
00:24:12,666 --> 00:24:14,500
Sort of the first
cash crop.
424
00:24:14,600 --> 00:24:16,900
It was the one that
economically could keep
425
00:24:17,000 --> 00:24:18,333
the early colonists
in business
426
00:24:18,433 --> 00:24:19,966
and in great part,
because there was
427
00:24:20,066 --> 00:24:21,666
a perfect storm
of the right plant,
428
00:24:21,766 --> 00:24:23,633
brought to the right place,
in the right climate,
429
00:24:23,733 --> 00:24:26,166
at the right time,
with, importantly,
430
00:24:26,266 --> 00:24:28,000
the right kind of soil
for growing it.
431
00:24:28,100 --> 00:24:29,533
Huh.
432
00:24:29,633 --> 00:24:31,066
JOHNSON:
Dave Montgomery studies
433
00:24:31,166 --> 00:24:34,266
how the earth's thinnest and
most fragile geological layer
434
00:24:34,366 --> 00:24:37,100
has shaped the destinies
of human societies--
435
00:24:37,200 --> 00:24:39,200
including ours.
436
00:24:39,300 --> 00:24:40,866
So what is soil?
437
00:24:40,966 --> 00:24:44,000
So soil is sort of the frontier
between the worlds of geology
438
00:24:44,100 --> 00:24:45,600
and the world of biology.
439
00:24:45,700 --> 00:24:47,466
It's that interface,
440
00:24:47,566 --> 00:24:50,733
and it's made dominantly
of rotten rocks.
441
00:24:50,833 --> 00:24:54,266
JOHNSON:
But what kind of rotten rock?
442
00:24:54,366 --> 00:24:58,100
Dave reveals the recipe
that makes life on land
443
00:24:58,200 --> 00:25:01,800
and all agriculture possible.
444
00:25:01,900 --> 00:25:04,866
The first ingredient is sand.
445
00:25:04,966 --> 00:25:09,800
JOHNSON:
Sand is any mineral
ground down into tiny grains
446
00:25:09,900 --> 00:25:13,233
by natural wear and tear.
447
00:25:13,333 --> 00:25:14,666
This looks like
a nice beach sand,
448
00:25:14,766 --> 00:25:16,566
it's just
little quartz grains.
449
00:25:16,666 --> 00:25:18,733
Little clear grains of quartz
is what I am seeing.
450
00:25:18,833 --> 00:25:20,066
Yeah, quartz and feldspar.
451
00:25:20,166 --> 00:25:21,733
It's not unlike
a California beach.
452
00:25:21,833 --> 00:25:24,966
JOHNSON:
Silt is next.
453
00:25:25,066 --> 00:25:29,500
Made of the same stuff as sand,
but ground much finer.
454
00:25:29,600 --> 00:25:32,266
MONTGOMERY:
It's too small to really see,
but you can feel the grit.
455
00:25:32,366 --> 00:25:34,033
If you put a little
on your teeth
456
00:25:34,133 --> 00:25:35,466
you'll feel the grit
between your teeth.
457
00:25:35,566 --> 00:25:36,466
Oh, yeah.
458
00:25:36,566 --> 00:25:37,733
It's really gritty.
459
00:25:37,833 --> 00:25:39,633
I don't really like
eating silt.
460
00:25:37,833 --> 00:25:39,633
No.
461
00:25:41,400 --> 00:25:42,733
JOHNSON:
The finest is clay,
462
00:25:42,833 --> 00:25:46,166
made up of mineral crystals
so tiny,
463
00:25:46,266 --> 00:25:49,100
they're visible
only with a microscope.
464
00:25:50,266 --> 00:25:51,700
This is all geology still.
465
00:25:51,800 --> 00:25:53,166
This is all geology,
this is the basis,
466
00:25:53,266 --> 00:25:54,800
the backbone
of making a soil.
467
00:25:54,900 --> 00:25:56,566
And the geological part,
468
00:25:56,666 --> 00:25:58,866
some combination
of these three components
469
00:25:58,966 --> 00:26:01,700
makes up about 40% to 50%
of the volume of most soils.
470
00:26:01,800 --> 00:26:03,133
So what's the rest?
471
00:26:04,566 --> 00:26:07,800
JOHNSON:
How about the rich black stuff
we associate with fertile soil?
472
00:26:07,900 --> 00:26:11,600
The stuff of life--
or, actually, of death.
473
00:26:11,700 --> 00:26:13,733
So it's nice and dark.
474
00:26:13,833 --> 00:26:15,166
It looks like
coffee grounds.
475
00:26:15,266 --> 00:26:16,300
So it's rotted
plant matter.
476
00:26:16,400 --> 00:26:18,100
You've got pieces
of plants...
477
00:26:18,200 --> 00:26:19,966
Oh, this smells nasty.
478
00:26:20,066 --> 00:26:21,300
I guess it's
dead stuff though, right?
479
00:26:21,400 --> 00:26:22,933
It's dead stuff.
480
00:26:23,033 --> 00:26:24,533
That's why it smells
so good.
481
00:26:24,633 --> 00:26:26,200
I'm going to put this
back in the jar.
482
00:26:26,300 --> 00:26:28,733
So that's it,
these four things?
483
00:26:28,833 --> 00:26:31,000
Well, then there's also
living matter,
484
00:26:31,100 --> 00:26:32,666
which in this case,
485
00:26:32,766 --> 00:26:34,300
we have worms.
486
00:26:34,400 --> 00:26:36,900
So you can think of them
the way that Charles Darwin did,
487
00:26:37,000 --> 00:26:38,133
as God's plowmen.
488
00:26:38,233 --> 00:26:40,733
They basically plow the fields.
489
00:26:40,833 --> 00:26:44,100
Underground, they're like
little underground miners.
490
00:26:45,800 --> 00:26:48,033
JOHNSON:
There's one last ingredient,
491
00:26:48,133 --> 00:26:51,300
a geologist's best friend.
492
00:26:51,400 --> 00:26:52,400
We have time
in a jar here?
493
00:26:52,500 --> 00:26:53,566
We got time
in a bottle here.
494
00:26:53,666 --> 00:26:54,566
We're not gonna open it.
495
00:26:54,666 --> 00:26:56,300
How much time do you have
in that bottle?
496
00:26:56,400 --> 00:26:59,133
There's only one way
to find out.
497
00:26:59,233 --> 00:27:00,566
Don't open that jar.
498
00:27:00,666 --> 00:27:02,133
It can be a million years
in that jar.
499
00:27:02,233 --> 00:27:03,066
It could be.
500
00:27:06,533 --> 00:27:08,533
JOHNSON:
The British colonists got lucky
501
00:27:08,633 --> 00:27:10,866
when they chose
to plant tobacco here.
502
00:27:10,966 --> 00:27:13,200
For tens of thousands of years,
503
00:27:13,300 --> 00:27:16,766
nature had been preparing the
soil along the Southeast coast,
504
00:27:16,866 --> 00:27:20,333
giving it all the right
ingredients,
505
00:27:20,433 --> 00:27:23,966
especially
an extra helping of sand.
506
00:27:24,066 --> 00:27:28,100
Perfect for growing
the original wacky weed.
507
00:27:28,200 --> 00:27:31,600
But they soon paid a price.
508
00:27:34,500 --> 00:27:36,600
It's not hard to see
what growing millions of pounds
509
00:27:36,700 --> 00:27:39,366
of tobacco to ship back home
did to the land.
510
00:27:39,466 --> 00:27:44,833
Even today, comparing soil
from the forest
511
00:27:44,933 --> 00:27:48,066
to soil from the tobacco field
tells the whole story.
512
00:27:49,333 --> 00:27:51,966
So over here on this side,
we've got the forest soil,
513
00:27:52,066 --> 00:27:53,533
which is probably
a lot more like
514
00:27:53,633 --> 00:27:55,266
the native soil was like
515
00:27:55,366 --> 00:27:56,833
when colonial agriculture
arrived in the New World.
516
00:27:56,933 --> 00:27:58,466
Yeah, lots of organic
matter in it
517
00:27:58,566 --> 00:28:00,533
and roots and twigs
and stuff like that.
518
00:28:00,633 --> 00:28:03,633
You notice the dark color
relative to the soil next to it,
519
00:28:03,733 --> 00:28:06,366
which is from the conventionally
plowed tobacco field.
520
00:28:06,466 --> 00:28:11,766
JOHNSON:
The sickly yellow color shows
the soil's exhaustion.
521
00:28:11,866 --> 00:28:17,133
These fields are lush today
thanks to chemical fertilizers.
522
00:28:17,233 --> 00:28:19,300
But the colonists
had no such tricks,
523
00:28:19,400 --> 00:28:21,666
and growers soon hit a wall.
524
00:28:21,766 --> 00:28:23,600
MONTGOMERY:
The erosive effects
of colonial agriculture
525
00:28:23,700 --> 00:28:26,366
were so apparent
on the American landscape
526
00:28:26,466 --> 00:28:29,066
that people at the highest
levels of American society
527
00:28:29,166 --> 00:28:30,666
were very concerned
about what it meant
528
00:28:30,766 --> 00:28:31,966
for the future of the country.
529
00:28:32,066 --> 00:28:34,800
Washington even wrote
in a letter in the 1790s
530
00:28:34,900 --> 00:28:36,966
to Alexander Hamilton
about his prediction
531
00:28:37,066 --> 00:28:39,533
that American society would be
compelled to push inland,
532
00:28:39,633 --> 00:28:41,000
to push westward,
533
00:28:41,100 --> 00:28:43,933
due to the search
for fresh and fertile soils
534
00:28:44,033 --> 00:28:47,800
after having worn out the soils
along the Eastern seaboard.
535
00:28:47,900 --> 00:28:50,533
JOHNSON:
But the founding fathers
needn't have worried.
536
00:28:53,666 --> 00:28:58,666
Because migrating farmers would
soon discover the Great Plains,
537
00:28:58,766 --> 00:29:02,900
with some of the best soil
in the world.
538
00:29:03,000 --> 00:29:05,966
MONTGOMERY:
Dirt is destiny
in that sense,
539
00:29:06,066 --> 00:29:08,133
where degrading the soils
of the Eastern seaboard
540
00:29:08,233 --> 00:29:10,700
and then opening up
the fresh fertile soils
541
00:29:10,800 --> 00:29:12,200
in the American Midwest
542
00:29:12,300 --> 00:29:14,333
served like a great magnet
pulling people westward
543
00:29:14,433 --> 00:29:16,766
towards the source of fertility
and prosperity
544
00:29:16,866 --> 00:29:19,566
in the heart of the country.
545
00:29:19,666 --> 00:29:24,033
JOHNSON:
The great magnet
of North American soil exerted
546
00:29:24,133 --> 00:29:26,100
an irresistible pull on those
with a pioneering spirit.
547
00:29:34,966 --> 00:29:39,733
But the westward expansion also
got a major shot of adrenaline
548
00:29:39,833 --> 00:29:41,566
with the discovery of a new gift
549
00:29:41,666 --> 00:29:46,633
from the geology
of the continent: gold.
550
00:29:48,133 --> 00:29:52,466
In 1848, Mexico ceded
to the U.S. a territory
551
00:29:52,566 --> 00:29:55,600
that included what would become
the state of California.
552
00:29:58,233 --> 00:30:01,100
At the time, San Francisco
was little more
553
00:30:01,200 --> 00:30:06,200
than a military garrison
with a population under 1,000.
554
00:30:06,300 --> 00:30:11,433
But that changed when James
Marshall found nuggets of gold
555
00:30:11,533 --> 00:30:15,866
in a streambed at Sutter's Mill
in Coloma, California.
556
00:30:15,966 --> 00:30:22,366
When word got out, California
became a hot destination.
557
00:30:22,466 --> 00:30:26,100
In 1849, about 80,000 people,
558
00:30:26,200 --> 00:30:29,733
called '49ers,
joined the gold rush.
559
00:30:29,833 --> 00:30:35,100
Over the next six years,
about 200,000 more followed,
560
00:30:35,200 --> 00:30:36,666
turning San Francisco
561
00:30:36,766 --> 00:30:39,533
into one of the largest cities
on the continent.
562
00:30:42,766 --> 00:30:45,100
By then, prospectors
had snatched up
563
00:30:45,200 --> 00:30:49,000
pretty much all the gold
to be found just lying around,
564
00:30:49,100 --> 00:30:52,133
and so the party
had to move underground.
565
00:30:54,800 --> 00:30:56,266
Pretty sweet place here.
566
00:30:56,366 --> 00:30:57,733
Yes, it's beautiful here.
567
00:31:00,400 --> 00:31:04,933
So they started mining
around here in 1849...
568
00:31:05,033 --> 00:31:09,566
JOHNSON:
Lisa White is a geologist
and a native San Franciscan.
569
00:31:09,666 --> 00:31:12,533
Her passion for California's
amazing geological history
570
00:31:12,633 --> 00:31:14,666
was bred in the bone.
571
00:31:14,766 --> 00:31:15,933
Let's go have a look.
572
00:31:17,233 --> 00:31:21,500
JOHNSON:
Who better to show me
this historically preserved mine
573
00:31:21,600 --> 00:31:24,233
in the Sierra Nevada mountains?
574
00:31:24,333 --> 00:31:26,233
The miners must have
been short guys.
575
00:31:26,333 --> 00:31:27,700
Well, I fit
right in here!
576
00:31:27,800 --> 00:31:29,100
Yeah, I guess you do!
577
00:31:29,200 --> 00:31:30,833
Not me.
578
00:31:30,933 --> 00:31:34,100
WHITE:
This is such an incredible mine
for so many different reasons.
579
00:31:34,200 --> 00:31:35,833
Unbelievably, they dug out
580
00:31:35,933 --> 00:31:38,633
the earliest part
of this mine by hand.
581
00:31:38,733 --> 00:31:40,333
Wow, look at that,
you can actually see
582
00:31:40,433 --> 00:31:42,333
the pick marks where
they carved this thing.
583
00:31:45,100 --> 00:31:47,533
As Lisa leads me further
into the mountain,
584
00:31:47,633 --> 00:31:50,333
we spot a change in the rock.
585
00:31:50,433 --> 00:31:52,033
Ah, here we go.
586
00:31:52,133 --> 00:31:53,366
JOHNSON:
That's something
different.
587
00:31:53,466 --> 00:31:54,900
WHITE:
It is, it is.
588
00:31:55,000 --> 00:31:59,600
It's a quartz vein, and it's
important and distinctive
589
00:31:59,700 --> 00:32:02,866
because when the miners would
locate these quartz veins,
590
00:32:02,966 --> 00:32:06,766
they knew they were in the area
they wanted to be for gold.
591
00:32:06,866 --> 00:32:08,766
So the gold is actually
in the quartz?
592
00:32:08,866 --> 00:32:10,800
The gold is in the quartz,
yes it is,
593
00:32:10,900 --> 00:32:13,966
and so looking for these
was the way to the gold.
594
00:32:14,066 --> 00:32:16,533
I've got a quartz sample
here in my pocket
595
00:32:16,633 --> 00:32:18,700
with some gold flakes in it.
596
00:32:18,800 --> 00:32:20,866
Wow, there's a lot of gold
in there actually, wow.
597
00:32:20,966 --> 00:32:22,333
It's really beautiful.
598
00:32:22,433 --> 00:32:24,966
Yeah, if you like gold!
599
00:32:25,066 --> 00:32:26,300
But the gold
is in the quartz
600
00:32:26,400 --> 00:32:28,233
and not in the rock
next to the quartz?
601
00:32:28,333 --> 00:32:31,100
Exactly, so that's key
to understanding its formation.
602
00:32:35,866 --> 00:32:40,233
JOHNSON:
When Earth was forming, most
heavy metals like iron and gold
603
00:32:40,333 --> 00:32:43,366
sank to the molten core.
604
00:32:43,466 --> 00:32:45,266
But as Earth cooled,
605
00:32:45,366 --> 00:32:48,866
small amounts remained
in the rocky mantle.
606
00:32:48,966 --> 00:32:53,133
Later, asteroids deposited
more of these metals.
607
00:32:53,233 --> 00:32:56,366
But for gold to work its way
back up to the surface,
608
00:32:56,466 --> 00:32:59,700
it had to hitch a ride on some
kind of geological shake-up,
609
00:32:59,800 --> 00:33:02,266
like an earthquake.
610
00:33:04,966 --> 00:33:06,600
WOMAN (on phone):
9-1-1.
611
00:33:06,700 --> 00:33:08,933
MAN:
...Cypress section of
the freeway has come down.
612
00:33:09,033 --> 00:33:11,933
JOHNSON:
Violent earthquakes like
this one in San Francisco
613
00:33:12,033 --> 00:33:14,466
cause serious damage
above ground.
614
00:33:17,866 --> 00:33:20,800
But they also wreak havoc
below the surface.
615
00:33:20,900 --> 00:33:24,100
Most people know that California
is earthquake country,
616
00:33:24,200 --> 00:33:27,100
but even in the past,
earthquakes were key
617
00:33:27,200 --> 00:33:29,933
because earthquakes
would fracture the rocks.
618
00:33:30,033 --> 00:33:32,366
And in many ways, the cracks,
619
00:33:32,466 --> 00:33:37,000
they're like pathways for fluids
from deep within the earth.
620
00:33:37,100 --> 00:33:39,433
JOHNSON:
Deep below, millions of years
of earthquakes
621
00:33:39,533 --> 00:33:41,666
and pressure from molten rock
622
00:33:41,766 --> 00:33:44,166
have created
a network of cracks.
623
00:33:44,266 --> 00:33:45,866
These provide pathways
624
00:33:45,966 --> 00:33:48,400
for superheated water
full of minerals,
625
00:33:48,500 --> 00:33:50,566
like gold
from deep in the earth.
626
00:33:50,666 --> 00:33:54,633
When that hot fluid rises up
through the fractured rock,
627
00:33:54,733 --> 00:33:59,433
it cools down, and the minerals
carried within crystalize.
628
00:33:59,533 --> 00:34:03,066
Over time, that builds up
a vein of quartz,
629
00:34:03,166 --> 00:34:06,233
and trapped inside the quartz
are bits of gold.
630
00:34:09,900 --> 00:34:11,733
Over millions of years,
631
00:34:11,833 --> 00:34:15,266
they formed the seams
found all over California.
632
00:34:15,366 --> 00:34:18,533
WHITE:
So every time you look
at a vein of quartz
633
00:34:18,633 --> 00:34:21,466
you're really seeing an ancient
earthquake in many ways.
634
00:34:21,566 --> 00:34:23,300
JOHNSON:
I've always thought
of earthquakes
635
00:34:23,400 --> 00:34:24,900
as very destructive
kinds of things,
636
00:34:25,000 --> 00:34:26,400
but looking at this,
637
00:34:26,500 --> 00:34:28,433
if earthquakes are involved
in the formation of gold,
638
00:34:28,533 --> 00:34:30,800
maybe there's a silver lining--
I guess a gold lining--
639
00:34:30,900 --> 00:34:32,833
to earthquakes.
640
00:34:38,566 --> 00:34:42,033
The California Gold Rush
didn't last very long.
641
00:34:42,133 --> 00:34:45,000
But between 1848 and 1860,
642
00:34:45,100 --> 00:34:49,600
it's estimated that more than
one million pounds of gold
643
00:34:49,699 --> 00:34:51,300
were found in these hills.
644
00:34:53,400 --> 00:34:55,699
Over the following years,
much of it made its way
645
00:34:55,800 --> 00:34:59,900
right here to the Old Mint
in San Francisco,
646
00:35:00,000 --> 00:35:03,233
affectionately called
The Granite Lady.
647
00:35:03,333 --> 00:35:06,533
This building
once held the machinery
648
00:35:06,633 --> 00:35:09,766
that turned California gold
into beautiful coins.
649
00:35:09,866 --> 00:35:12,800
It's no longer in operation,
but there's a vault here
650
00:35:12,900 --> 00:35:17,866
holding something
that these days is truly rare.
651
00:35:21,200 --> 00:35:24,233
Oh, man.
652
00:35:24,333 --> 00:35:26,500
This thing is phenomenal.
653
00:35:26,600 --> 00:35:30,166
A massive nugget of gold,
654
00:35:30,266 --> 00:35:34,800
the largest to be found
in California in decades.
655
00:35:34,900 --> 00:35:38,033
Worth around $400,000!
656
00:35:38,133 --> 00:35:41,700
It was probably buried
about 40 million years ago,
657
00:35:41,800 --> 00:35:45,233
and it was dug up
a few months ago.
658
00:35:45,333 --> 00:35:49,800
Gold is so dense that
it doesn't look that large,
659
00:35:49,900 --> 00:35:51,633
but it feels really heavy.
660
00:35:51,733 --> 00:35:54,866
It's like five pounds packed
into the palm of my hand.
661
00:35:54,966 --> 00:35:57,166
You feel both the power
of the earth
662
00:35:57,266 --> 00:35:59,300
and geology and chemistry,
663
00:35:59,400 --> 00:36:01,766
but you also feel the weight
of human history.
664
00:36:01,866 --> 00:36:04,433
Gold has driven
the behavior of humans
665
00:36:04,533 --> 00:36:06,133
since it was first found.
666
00:36:06,233 --> 00:36:09,200
I actually have
gold fever right now.
667
00:36:09,300 --> 00:36:11,000
I want to take a bite
out of this thing.
668
00:36:11,100 --> 00:36:13,366
It's an amazing thing.
669
00:36:13,466 --> 00:36:16,700
Striking it rich
in gold or silver
670
00:36:16,800 --> 00:36:19,366
was the dream of thousands
of prospectors.
671
00:36:19,466 --> 00:36:21,566
But what other treasures
672
00:36:21,666 --> 00:36:23,866
did the geology of the continent
have to offer?
673
00:36:29,266 --> 00:36:32,700
Turns out the real money
was about to be made back east,
674
00:36:32,800 --> 00:36:35,733
in the iron and coal mines
675
00:36:35,833 --> 00:36:40,366
poised to power the nation's
next great leap.
676
00:36:45,133 --> 00:36:47,600
(whistling)
677
00:36:47,700 --> 00:36:48,766
By the 1860s,
678
00:36:48,866 --> 00:36:51,500
the industrialization
of the American economy
679
00:36:51,600 --> 00:36:54,366
was going full steam,
literally.
680
00:36:54,466 --> 00:36:55,833
Unbelievable.
681
00:36:57,400 --> 00:36:59,833
Perhaps the one technology
that best symbolized
682
00:36:59,933 --> 00:37:03,633
the massive transformation
underway was this:
683
00:37:03,733 --> 00:37:05,733
the steam locomotive.
684
00:37:13,133 --> 00:37:19,000
In 1863, the U.S. government
launched an ambitious effort:
685
00:37:19,100 --> 00:37:23,900
to unite the coasts with
a transcontinental railroad.
686
00:37:26,600 --> 00:37:30,433
Two railroad companies set out
to meet in the middle.
687
00:37:30,533 --> 00:37:32,933
Progress from the east
was relatively rapid
688
00:37:33,033 --> 00:37:35,866
thanks to the wide-open prairie
689
00:37:35,966 --> 00:37:39,033
and a natural pass
through the Rockies.
690
00:37:39,133 --> 00:37:40,866
But construction
of the western line
691
00:37:40,966 --> 00:37:42,766
progressed much more slowly,
692
00:37:42,866 --> 00:37:47,233
impeded by the Sierra
Nevada Mountains.
693
00:37:47,333 --> 00:37:50,966
The only option:
cut a pass by hand.
694
00:37:54,400 --> 00:37:55,633
From this logging train,
695
00:37:55,733 --> 00:37:58,600
we can see just
what they were up against.
696
00:38:00,300 --> 00:38:03,166
This is granite,
an incredibly hard rock,
697
00:38:03,266 --> 00:38:05,333
and the people that had to build
the first railroad
698
00:38:05,433 --> 00:38:08,233
across the Sierra Nevadas
cut through this rock
699
00:38:08,333 --> 00:38:12,600
with hand tools, sledge hamms,
steel drills, and explosives.
700
00:38:12,700 --> 00:38:14,600
Incredibly hard work.
701
00:38:14,700 --> 00:38:16,466
(hammer ringing)
702
00:38:19,300 --> 00:38:23,000
They relied heavily
on Chinese immigrant laborers.
703
00:38:23,100 --> 00:38:27,133
In harsh conditions,
they carved 15 tunnels,
704
00:38:27,233 --> 00:38:30,633
largely using hand tools
and dynamite.
705
00:38:30,733 --> 00:38:32,066
(explosion)
706
00:38:35,433 --> 00:38:38,733
The longest stretched
about a third of a mile
707
00:38:38,833 --> 00:38:42,033
and took 15 months to complete.
708
00:38:45,100 --> 00:38:51,566
Eventually, the two lines met
in Utah on May 10, 1869.
709
00:38:51,666 --> 00:38:53,966
It had taken six years,
710
00:38:54,066 --> 00:38:59,066
but America's new East-West
railroad was open for business.
711
00:39:01,233 --> 00:39:03,366
The building of the
transcontinental railroad
712
00:39:03,466 --> 00:39:05,100
was an epic endeavor.
713
00:39:05,200 --> 00:39:06,933
But once it was done,
714
00:39:07,033 --> 00:39:09,200
it linked the United States
from coast to coast,
715
00:39:09,300 --> 00:39:10,700
and within 50 years of that,
716
00:39:10,800 --> 00:39:12,400
there was a quarter
of a million miles
717
00:39:12,500 --> 00:39:16,500
of railroad tracks
spanning the continent.
718
00:39:19,166 --> 00:39:23,766
And with the two coasts linked,
the economy roared,
719
00:39:23,866 --> 00:39:26,566
fed by the continent's
abundant geological gifts
720
00:39:26,666 --> 00:39:30,566
of coal, metals,
and other resources,
721
00:39:30,666 --> 00:39:33,566
and eventually
by a powerful new fuel.
722
00:39:41,700 --> 00:39:43,833
I've come to the great city
of Los Angeles.
723
00:39:43,933 --> 00:39:45,733
It's an amazing
metropolitan area.
724
00:39:45,833 --> 00:39:48,600
Something like 18 million people
live here.
725
00:39:48,700 --> 00:39:52,500
That's a lot of people,
and they use a lot of resources.
726
00:39:54,500 --> 00:39:56,033
It's no secret that Los Angeles
727
00:39:56,133 --> 00:39:58,966
has an insatiable thirst
for oil.
728
00:39:59,066 --> 00:40:01,633
But what's less well known
729
00:40:01,733 --> 00:40:04,400
is the area's history
as a major producer.
730
00:40:11,333 --> 00:40:14,733
That story takes me back
to the La Brea tar pits.
731
00:40:17,400 --> 00:40:20,866
The natural asphalt that trapped
so many ancient animals
732
00:40:20,966 --> 00:40:22,933
is actually a form of oil.
733
00:40:26,500 --> 00:40:27,833
Paleontologist Carrie Howard
734
00:40:27,933 --> 00:40:29,833
takes me into one
of the fossil pits
735
00:40:29,933 --> 00:40:33,633
to see LA's black gold up close.
736
00:40:33,733 --> 00:40:35,466
I'm just dying
to get down in there
737
00:40:35,566 --> 00:40:37,566
and scrape some of those bones
right now.
738
00:40:37,666 --> 00:40:38,733
But if I did that,
739
00:40:38,833 --> 00:40:40,766
I would actually probably be
stuck, right?
740
00:40:40,866 --> 00:40:43,300
HOWARD:
Yeah, even if you just stepped
right there,
741
00:40:43,400 --> 00:40:44,733
don't be fooled.
742
00:40:44,833 --> 00:40:48,000
Even, like, an inch
could stick your shoe,
743
00:40:48,100 --> 00:40:50,000
and then you'd definitely
need help.
744
00:40:50,100 --> 00:40:53,033
JOHNSON:
This sticky oil was produced
745
00:40:53,133 --> 00:40:57,233
by the slow accumulation
and burial of marine plankton
746
00:40:57,333 --> 00:40:59,300
over millions of years.
747
00:40:59,400 --> 00:41:01,433
Compressed
and heated underground
748
00:41:01,533 --> 00:41:03,233
and turned into thick oil,
749
00:41:03,333 --> 00:41:07,733
it's managed to seep upwards
to bubble up here.
750
00:41:07,833 --> 00:41:10,066
It may not seem like much,
751
00:41:10,166 --> 00:41:13,333
but there's a lot more
where this came from.
752
00:41:13,433 --> 00:41:16,733
These tar pits
with their fantastic fossils
753
00:41:16,833 --> 00:41:18,900
are just the tip of the iceberg,
754
00:41:19,000 --> 00:41:23,633
because deep beneath the streets
is a tremendous amount of oil.
755
00:41:28,300 --> 00:41:30,966
Once Californians
realized the scale
756
00:41:31,066 --> 00:41:32,266
of this geological treasure,
757
00:41:32,366 --> 00:41:34,733
they kinda went nuts
exploiting it.
758
00:41:37,633 --> 00:41:40,066
What I've got here is a picture
from 1901 of this very spot,
759
00:41:40,166 --> 00:41:44,033
and I can see a house down there
that's in this photograph.
760
00:41:44,133 --> 00:41:45,700
But what's not here today
761
00:41:45,800 --> 00:41:48,900
are the dozens of oil derricks
that were here in 1901.
762
00:41:49,000 --> 00:41:51,133
This place was
an incredible oil field.
763
00:41:54,200 --> 00:41:57,233
Oil is really the DNA
of Los Angeles.
764
00:41:57,333 --> 00:42:00,133
It was discovered here first
in 1892,
765
00:42:00,233 --> 00:42:03,766
and it kicked off
an amazing oil boom.
766
00:42:03,866 --> 00:42:06,600
And even today,
Los Angeles is defined by oil.
767
00:42:11,266 --> 00:42:13,900
In and around Los Angeles,
768
00:42:14,000 --> 00:42:15,433
there are oil wells
almost everywhere.
769
00:42:20,066 --> 00:42:22,033
Pretty amazing.
770
00:42:22,133 --> 00:42:24,900
Right here in the middle
of a neighborhood
771
00:42:25,000 --> 00:42:26,800
is full-on oil rigs.
772
00:42:26,900 --> 00:42:28,700
There's a house
and there's a pump jack,
773
00:42:28,800 --> 00:42:31,066
and a house and a pump jack.
774
00:42:31,166 --> 00:42:34,866
Looking down, and it's a great
view of the city of Los Angeles.
775
00:42:34,966 --> 00:42:37,966
There's oil rigs
all over the place down there.
776
00:42:42,166 --> 00:42:46,166
Los Angeles County has more
than 3,000 active oil wells
777
00:42:46,266 --> 00:42:53,933
tirelessly pumping more than
14 million barrels a year.
778
00:42:54,033 --> 00:42:55,466
But that's just a tiny fraction
779
00:42:55,566 --> 00:42:57,500
of the total
North American output.
780
00:43:00,500 --> 00:43:03,500
From Mexico to the oil sands
of Alberta, Canada,
781
00:43:03,600 --> 00:43:05,333
and the Arctic Coast,
782
00:43:05,433 --> 00:43:07,533
we're pumping oil
and natural gas
783
00:43:07,633 --> 00:43:11,333
out of the ground
at a record rate.
784
00:43:11,433 --> 00:43:14,833
Which begs the question:
should we?
785
00:43:14,933 --> 00:43:19,366
When we burn fossil fuels,
the release of carbon dioxide
786
00:43:19,466 --> 00:43:23,033
causes Earth's atmosphere
and oceans to warm.
787
00:43:23,133 --> 00:43:26,033
As a result,
glaciers are melting
788
00:43:26,133 --> 00:43:28,233
and sea levels are rising
789
00:43:28,333 --> 00:43:31,833
much faster than at the end
of the last ice age.
790
00:43:31,933 --> 00:43:35,200
Our impact on the planet
is a huge concern,
791
00:43:35,300 --> 00:43:40,033
but as a geologist, I also worry
about the nasty surprises
792
00:43:40,133 --> 00:43:43,666
our continent has in store
for us.
793
00:43:47,033 --> 00:43:50,000
In the Pacific Northwest,
794
00:43:50,100 --> 00:43:55,233
there are chilling clues
about a future natural disaster.
795
00:43:55,333 --> 00:43:59,933
This is an old-growth
rainforest.
796
00:44:00,000 --> 00:44:00,066
Some of these trees
are more than 500 years old,
797
00:44:05,166 --> 00:44:08,966
and they've witnessed events
we can barely imagine.
798
00:44:09,066 --> 00:44:11,000
And it's trees like these
799
00:44:11,100 --> 00:44:14,366
not too far from here
that played a key role
800
00:44:14,466 --> 00:44:17,133
in resving a mystery
of epic proportions.
801
00:44:22,566 --> 00:44:26,166
Meet geologist Brian Atwater.
802
00:44:26,266 --> 00:44:30,166
He and I are paddling up
the Copalis, a coastal river
803
00:44:30,266 --> 00:44:35,100
that rises and falls
with Pacific Ocean tides.
804
00:44:35,200 --> 00:44:37,833
We're here at low tide.
805
00:44:37,933 --> 00:44:39,333
But at high tide,
806
00:44:39,433 --> 00:44:41,700
the river can rise enough
to overflow its banks,
807
00:44:41,800 --> 00:44:46,466
flooding the surrounding marshes
with salt water.
808
00:44:46,566 --> 00:44:49,766
But it wasn't always that way.
809
00:44:49,866 --> 00:44:52,333
Once, this was a lush
coastal rainforest.
810
00:44:54,500 --> 00:44:55,633
Now, all that remains
811
00:44:55,733 --> 00:44:59,066
are massive roots sticking out
of the eroded riverbank
812
00:44:59,166 --> 00:45:04,533
and the trunks
of long-dead cedar trees--
813
00:45:04,633 --> 00:45:06,166
a ghost forest.
814
00:45:11,100 --> 00:45:14,100
Brian has brought me here
to show me evidence
815
00:45:14,200 --> 00:45:16,800
of one of the worst earthquakes
to hit North America
816
00:45:16,900 --> 00:45:19,766
since human beings arrived here.
817
00:45:19,866 --> 00:45:22,433
He's found signs in a place
818
00:45:22,533 --> 00:45:25,100
where geologists
feel right at home:
819
00:45:25,200 --> 00:45:26,766
in the mud.
820
00:45:37,133 --> 00:45:40,133
Slicing into the bank
reveals three layers.
821
00:45:43,233 --> 00:45:45,733
They tell a story of change
over time.
822
00:45:45,833 --> 00:45:51,000
The lowest once supported
a healthy rain forest.
823
00:45:51,100 --> 00:45:53,366
BRIAN ATWATER:
So this is almost like
a garden soil, right?
824
00:45:53,466 --> 00:45:55,233
But it's got tree roots in it.
825
00:45:55,333 --> 00:45:57,566
It's a forest floor soil.
826
00:45:57,666 --> 00:46:03,133
JOHNSON:
Just above is a layer of sand
entirely out of place.
827
00:46:03,233 --> 00:46:05,733
Its sharp definition
tells Atwater
828
00:46:05,833 --> 00:46:10,333
that whatever put it here
came fast and furious.
829
00:46:10,433 --> 00:46:12,500
You don't see sign
of a gradual change from here
830
00:46:12,600 --> 00:46:14,566
because there's such
a black and white difference
831
00:46:14,666 --> 00:46:17,100
between this and this.
832
00:46:17,200 --> 00:46:19,300
How do we do this combination?
833
00:46:19,400 --> 00:46:24,933
How do we go from forest floor
to some kind of muddy flat
834
00:46:25,033 --> 00:46:30,400
and have a sand layer brought in
first, right at that time?
835
00:46:30,500 --> 00:46:34,866
JOHNSON:
The answer lies
about 80 miles away
836
00:46:34,966 --> 00:46:37,866
at the bottom
of the Pacific Ocean.
837
00:46:37,966 --> 00:46:40,900
It's called the Cascadia
subduction zone,
838
00:46:41,000 --> 00:46:45,100
a 700-mile-long crack
in the crust of the planet.
839
00:46:45,200 --> 00:46:47,600
It's where a Pacific Ocean plate
840
00:46:47,700 --> 00:46:50,833
is trying to slide
under the North American plate.
841
00:46:50,933 --> 00:46:52,700
(plates scraping)
842
00:46:52,800 --> 00:46:56,500
But the plates are stuck.
843
00:46:56,600 --> 00:46:58,300
So the story there, you know, is
844
00:46:58,400 --> 00:47:00,166
with the down-going
oceanic plate
845
00:47:00,266 --> 00:47:04,400
and the overriding continental
plate stuck together here,
846
00:47:04,500 --> 00:47:06,900
they go closer and closer
like that,
847
00:47:07,000 --> 00:47:10,700
and the overriding plate
gets shortened and bulges up.
848
00:47:10,800 --> 00:47:15,033
JOHNSON:
The old growth forest that once
stood around the Copalis River
849
00:47:15,133 --> 00:47:17,500
sat on that bulge.
850
00:47:17,600 --> 00:47:21,833
But then the plates broke free
along the fault,
851
00:47:21,933 --> 00:47:24,333
causing a violent earthquake,
852
00:47:24,433 --> 00:47:28,933
dropping 600 miles of coastline
as much as five feet
853
00:47:29,033 --> 00:47:33,266
and into the tidal zone,
where it sits today.
854
00:47:33,366 --> 00:47:35,333
The local landscape drops.
855
00:47:35,433 --> 00:47:37,833
The ghost forest
goes for a swim.
856
00:47:37,933 --> 00:47:38,733
That's it for them.
857
00:47:40,266 --> 00:47:42,633
But the disaster wasn't over.
858
00:47:42,733 --> 00:47:44,833
That same tectonic rupture
859
00:47:44,933 --> 00:47:48,966
also drove the edge
of the continental plate upward
860
00:47:49,066 --> 00:47:51,466
and triggered a series
of huge waves--
861
00:47:51,566 --> 00:47:53,400
a tsunami.
862
00:47:55,566 --> 00:47:57,166
The tsunami comes in.
863
00:47:57,266 --> 00:47:59,066
That's the first thing
the forest gets to see.
864
00:48:00,800 --> 00:48:03,666
JOHNSON:
What the forest sees is a rush
of salt water and sand
865
00:48:03,766 --> 00:48:06,633
inundating the land,
866
00:48:06,733 --> 00:48:10,000
the final blow
from a massive fault rupture
867
00:48:10,100 --> 00:48:12,033
that turned an old-growth
rainforest...
868
00:48:14,400 --> 00:48:16,966
...into this.
869
00:48:17,066 --> 00:48:20,233
We now know that this
cataclysmic one-two punch
870
00:48:20,333 --> 00:48:23,833
took place in the year 1700.
871
00:48:23,933 --> 00:48:28,900
Today, everyone wants to know:
will it happen again?
872
00:48:29,000 --> 00:48:32,500
Is the Pacific Northwest
living on borrowed time?
873
00:48:34,900 --> 00:48:36,766
Tsunami is running.
874
00:48:47,100 --> 00:48:49,100
JOHNSON:
At Oregon State University,
875
00:48:49,200 --> 00:48:51,433
Chris Goldfinger studies
deep-sea earthquakes
876
00:48:51,533 --> 00:48:55,300
that can cause
devastating tsunamis.
877
00:49:02,100 --> 00:49:04,166
He's examined hundreds
of sediment cores
878
00:49:04,266 --> 00:49:06,066
from the sea floor,
879
00:49:06,166 --> 00:49:10,000
sampled all along the 700-mile
Cascadia subduction zone.
880
00:49:13,833 --> 00:49:16,600
Analyzing each one,
he's assembled a history
881
00:49:16,700 --> 00:49:20,466
of earthquakes
going back 10,000 years.
882
00:49:20,566 --> 00:49:24,233
And the news is not good.
883
00:49:24,333 --> 00:49:27,466
Chris estimates that
severe earthquakes strike
884
00:49:27,566 --> 00:49:31,500
somewhere along the fault line
about every 240 years,
885
00:49:31,600 --> 00:49:36,800
most often in Oregon
and Northern California.
886
00:49:36,900 --> 00:49:39,700
We're now 315 years
into a 240-year average,
887
00:49:39,800 --> 00:49:42,200
and so that drives
the probability up quite a bit.
888
00:49:42,300 --> 00:49:45,733
It's up around 37%
in the next 50 years.
889
00:49:45,833 --> 00:49:48,100
(rumbling)
890
00:49:48,200 --> 00:49:52,200
JOHNSON:
Today, seismologists warn
that the next big one
891
00:49:52,300 --> 00:49:55,766
in the Northwest
could be even more destructive
892
00:49:55,866 --> 00:50:00,500
than the earthquake and tsunami
that struck Japan in 2011.
893
00:50:02,866 --> 00:50:06,300
Luckily, there is time
to prepare,
894
00:50:06,400 --> 00:50:09,833
thanks to a warning
from an ancient disaster
895
00:50:09,933 --> 00:50:14,033
written in the land.
896
00:50:14,133 --> 00:50:16,100
Geology gives us many,
many examples
897
00:50:16,200 --> 00:50:19,333
where what we've learned from
interrogating the earth's past
898
00:50:19,433 --> 00:50:21,833
prepares us
for the earth's future.
899
00:50:24,600 --> 00:50:27,000
The relentless forces
beneath the earth
900
00:50:27,100 --> 00:50:31,266
will continue shaping our
continent far into the future,
901
00:50:31,366 --> 00:50:33,966
as they have
from the very beginning,
902
00:50:34,066 --> 00:50:37,866
since the first land formed
from molten rock
903
00:50:37,966 --> 00:50:41,833
and the pieces of our homeland
slid into place.
904
00:50:41,933 --> 00:50:46,900
As seas and mountains
rose and fell,
905
00:50:47,000 --> 00:50:52,933
as creatures small and mighty
lived and died here,
906
00:50:53,033 --> 00:50:56,633
geology has profoundly shaped
our destinies
907
00:50:56,733 --> 00:50:59,633
ever since we set foot
upon these shores--
908
00:50:59,733 --> 00:51:03,433
soil, oil, minerals.
909
00:51:03,533 --> 00:51:07,800
The power of the rocks beneath
our feet cannot be ignored.
910
00:51:07,900 --> 00:51:10,266
So what can we expect?
911
00:51:10,366 --> 00:51:14,866
Not just in our lifetimes,
but over the serious long haul?
912
00:51:18,033 --> 00:51:22,000
Well, over the next
175 million years,
913
00:51:22,100 --> 00:51:24,733
geologists predict
that North America
914
00:51:24,833 --> 00:51:28,366
will slowly converge
with Europe and Africa
915
00:51:28,466 --> 00:51:32,833
until eventually, the Atlantic
will completely close.
916
00:51:32,933 --> 00:51:38,366
And once again, we'll be part
of one giant super continent:
917
00:51:38,466 --> 00:51:41,533
Pangea Ultima.
918
00:51:41,633 --> 00:51:42,733
North America today
919
00:51:42,833 --> 00:51:44,700
is just the middle
of this continent's
920
00:51:44,800 --> 00:51:46,433
long and interesting story,
921
00:51:46,533 --> 00:51:48,433
and it will go on
for tens of millions
922
00:51:48,533 --> 00:51:51,233
and hundreds of millions
of years into the future.
923
00:51:52,666 --> 00:51:55,666
Because in geology,
one thing is for sure:
924
00:51:55,766 --> 00:51:58,233
no landscape is permanent.
925
00:52:18,133 --> 00:52:20,966
The investigation continues
on
926
00:52:18,133 --> 00:52:20,966
line
927
00:52:18,133 --> 00:52:20,966
The three-part
928
00:52:18,133 --> 00:52:20,966
NOVA
929
00:52:18,133 --> 00:52:20,966
series
"Making North America"
930
00:52:21,066 --> 00:52:22,633
is available on DVD.
931
00:52:22,733 --> 00:52:28,066
To order, visit shoppbs.org
or call 1-800-PLAY-PBS.
932
00:52:28,166 --> 00:52:30,833
NOVA
933
00:52:28,166 --> 00:52:30,833
is also available
for download from iTunes.
934
00:52:28,166 --> 00:52:59,900
Be more. PBS.