Blue Planet Page #3

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for the onslaught.

We are under a hurricane warning.

Officials of Civil Defense

are advising voluntary evacuation...

...of the Berry Islands.

Hurricane Hugo,

after ravaging Puerto Rico...

...tore into South Carolina.

What was once a national forest...

...is now a heap of kindling.

Where once there was a house...

...only the front steps remain.

Overnight...

...nature's fury

has devastated entire communities.

But, then, as quickly as it struck...

...the storm vanishes...

...and the eastern seaboard

is calm once more.

There are, however, other catastrophic

events affecting our planet.

They are far more violent than any storm.

The Earth is continually pelted

by a hail of objects from space.

Most are tiny

and burn up in the atmosphere.

But, every now and then,

a big one gets through.

Some 30,000 years ago,

a piece of an asteroid...

...weighing perhaps 300,000 tons...

...slammed into Arizona.

It blasted out a crater

almost 600 feet deep.

As collisions go, it was a small one.

From space, we can see the scars

from much bigger impacts on Earth.

This one in Canada is 60 miles across.

The effects of a similar collision

may have wiped out the dinosaurs.

The young Earth was once

completely covered by impact craters.

But most have been erased...

...by the powerful forces

which keep changing the face of our planet.

From orbit, we see evidence

for the most astonishing...

...geological discovery of our time:

The Earth's crust is broken

into about a dozen moving plates.

Here, a giant crack extends out

to the right...

...from the Sinai Peninsula

through the Dead Sea.

In a closer view...

...you can see how the Sinai,

shaped like a triangle...

...has wrenched away from Saudi Arabia,

on the far right.

The rift that opened between them

lies under the Gulf of Aqaba.

Most of the rifts are on the sea floor.

To search for them,

we need vehicles similar to spaceships.

We are on a journey, two miles down...

...to the very bottom of the ocean.

We will enter a world

that has never seen sunlight.

And yet, the ocean floor

is alive with exotic creatures.

They thrive on nutrients in the water...

...which is heated

by the Earth's great furnace beneath.

Here, in mid ocean,

at the boundary between two plates...

...molten rock pushes up from the interior.

These lava chimneys

are actually miniature volcanoes.

Just as one of the Earth's systems

recycles water...

...another recycles rock.

As new crust

is added to the Earth's surface here...

...the other edge of the plate...

...perhaps thousands of miles away...

...sinks back into the Earth's interior.

As it melts...

...volcanoes erupt.

This is Sakura-jima Volcano, in Japan.

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