:08:02
overriding other plates...
:08:05
plunging to destruction
:08:06
within the interior
from which they formed.
:08:11
The movements of the plates
are sustained
:08:13
by the continuous creation
of new earth's crust
:08:17
The process- one of four
major tectonic processes-
:08:21
is called "seafloor spreading."
:08:24
lt occurs
within the central rifts
:08:26
of the great mid-ocean ridges
:08:28
which wind for 40,000 miles
across the ocean floors.
:08:33
Beneath these rifts,
Earth's crust is thinnest
:08:37
and the pressures of the magma
rising from the fiery interior
:08:40
are relentless.
:08:43
The magma forces its way upward
:08:45
entering the rift
between the plates
:08:47
spreading the seafloor,
breaking to its surface
:08:51
in spectacular
undersea lava forms.
:09:12
Along this great system
of mid-ocean ridges
:09:14
suddenly volcanoes are born
:09:16
and ashy islands,
black and burning
:09:19
are thrust up out of the sea.
:09:22
We are witnessing the birth
of the island of Surtsey
:09:25
near lceland.
:09:33
For months,
this tiny ashen island
:09:35
waged a battle for survival
against the sea.
:09:39
lts survival depended
:09:39
on the surfacing of lava
from deep within the rift-
:09:43
lava which would armor Surtsey
:09:45
against the waves
of the north Atlantic.
:09:48
Surtsey had become
the newest battleground
:09:50
in Earth's oldest war-
:09:52
ln cessant forces of erosion,
relentless powers of creation.