WEBVTT

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[sil.]

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[music]

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In the heart of the Pacific Northwest

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ancient rock formations are
exposed in rugged mountains

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and rocky gorges. Hells Canyon,

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North America\'s deepest river canyon
offers an extraordinary passage

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through the geologic past. On
the border of Oregon and Idaho,

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the Snake River cuts through
8,000 feet of rocks

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that are as old as 350 million years.

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The older rock formations in Hells Canyon

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and in the rugged terrane surrounding it
are very unusual in their geologic makeup.

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Scientists discovered
that these rocks formed

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in a totally different
environment than today\'s.

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In fact, they were not part of
the continent when they formed.

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These formations are
exotic to North America.

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Geologists call them Exotic Terranes.

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I\'m not sure how far back this (inaudible).

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The exotic terranes of the Pacific Northwest
what undiscovered until recently.

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Ancient rock formations are exposed,

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but most have been highly altered by
geologic and another natural forces.

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These conditions kept
geologic secrets well hidden.

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Geologist Tracy Vallier

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began studying Hells
Canyon in the early 1960s.

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He was soon joined by other scientists
in exploring this new geologic frontier.

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Since much of it is wilderness, roads
and at the edge of the back country,

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most of the geology is learned on foot. If you
take a look and that way you can follow me.

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I\'ll probably be going right up… right up
that grassy slope. I\'ll be turning right

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and I\'ll go behind that big cliff. I\'ll probably there
by six, but listen at four o\'clock turn your radio on

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and I\'ll be talking to you.
Okay, that\'s great. Okay.

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[music]

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At 100 miles of canyon here unmanned
geologically nothing know about it.

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There are very few places
in the world right now

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we can go into an area that\'s been on that,
that another geologist hasn\'t worked at,

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so it was really a… a
challenging, it still is.

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Geologist soon learned that
the Hells Canyon region

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was very unique geologically. It is located
in some of the most rugged terrane

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in the Pacific Northwest. This
area includes Hells Canyon

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and the Seven Devils and
Wallowa Mountain Ranges.

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It is known as the Wallowa Terrane.

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We\'re sitting on the sides of an ancient
volcano that at one time was underwater

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maybe as much as a mile
underwater and under ocean water.

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The Wallowa Terrane contains large
formations of these odd-looking rocks.

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They are called pillow
lavas and they only form

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where volcanic lava flows into water.

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[sil.]

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Pillow lavas are forming today around
many volcanic islands including Hawaii.

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The pillow lavas in the Wallowa
Terrane also formed in the ocean

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over 200 million years ago.

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Today, these rocks are found in the Seven
Devils Mountains near Hells Canyon

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over 9,000 feet above sea level.

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The Pacific Ocean is 350 miles away.
Somehow these rocks were moved

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far away from their original
location under the ocean.

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[music]

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George Stanley is a paleontologist. He studies
fossils and life forms that lived in ancient oceans.

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Stanley is very interested in an unusual
rock formation in Hells Canyon,

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which can only be reached
by hiking a steep ridge

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far above the Snake River. That maybe
a fossil there. Hang onto that one.

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Here\'s another one.

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I\'m sitting right here on the Martin Ridge
limestone and they\'re just like this one

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have yielded hundreds of fossils, literally
thousands of fossils that come out of this bed.

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Umm… Brachiopods, coral nails, clamps

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a whole variety of fossils have been found right in these
beds and it\'s what paleontologists would call a goldmine.

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Limestone is a kind of rock
that forms in the ocean.

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It consists of the skeletons
of sea animals and plants.

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George Stanley has collected thousands of
fossils from the Martin Ridge limestone.

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He takes them back to his lab in Montana
where they undergo months of careful study.

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[music]

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So we all prepared for the
right strength about 7% or so.

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In the lab, the limestone is treated with
hydrochloric acid, this dissolves the weak rock

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and leaves fossils intact.

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[sil.]

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With this technique intricate
details are enhanced for study,

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the ages of the fossils are determined as
well as the environment where they lived.

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It was soon discovered that some
of the fossils from Hells Canyon

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were part of an ancient
tropical coral reef.

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[music]

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The startling discovery added another twist
to the geologic story of Hells Canyon.

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Coral reefs only grow near the
equator in warm ocean water.

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Yet here what parts of a fossil reef

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over 3,000 miles north of the equator
and thousands of feet above sea level.

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Stanley\'s work confirm that the ancient
rocks of Hells Canyon formed in the ocean

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and they could\'ve formed
thousands of miles away

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in a tropical setting that bears no
resemblance to Hells Canyon today.

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[sil.]

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As studies progressed in the Pacific Northwest, scientists
embarked on geological studies in the Pacific Ocean,

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working day and night from specially
equipped research vessels.

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They explored the geology of the
Earth\'s crust beneath the sea.

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They also study the volcanic island
chains that docked the Pacific Ocean.

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Nobody could predict that this research
would solve many geologic mysteries

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on the North American Continent.

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[music]

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This is Anatahan Island.

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It is really just the top of
a giant underwater volcano.

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Anatahan rises near the equator in the western
Pacific Ocean. It is one of the Mariana Islands

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which include the Islands
of Saipan and Guam.

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[sil.]

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Anatahan is an active volcano.

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In these pictures it is
dangerously close to erupting.

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A small village on the island was
evacuated because of the imminent danger.

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When this simmering volcano finally erupts, it
will probably be sudden and extremely powerful.

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[sil.]

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Just to the north of Anatahan,

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the Island of Pagan had
already come to life.

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Explosive eruptions like this one are
typical of Mariana Island volcanoes.

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To learn what causes these
volcanoes, we must first understand

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a geologic concept called plate tectonics.

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The Earth\'s crust is made of separate pieces
called plates that fit together like a puzzle.

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The plates are floating on a hot
plastic like material below.

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Some of the plates are pulling away
from each other and some are colliding.

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[music]

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The Mariana Islands are located where two of
the Earth\'s crustal plates are colliding.

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If we remove the ocean water around the islands,
the collision is revealed on the sea floor.

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The plates come together just
east of the Mariana Islands.

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By looking beneath the sea floor, we have an
even better view of the colliding plates.

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The collision formed a deep
canyon near the island,

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this is the Mariana
Trench, which bottoms out

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at 36,200 feet below sea level,
The lowest spot on Earth.

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Mount Everest would
easily fit in the trench

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with over a mile to spare
before reaching sea level.

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Plate tectonics is driving the two plates
together at the rate of a few inches per year.

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The plate on the right which
is the heavier of the two

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is sinking below the lighter plate,
this is called a subduction zone.

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As the plate sinks deeper, it melts.

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Magma is created, which can force
its way up through the plate above.

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Volcanoes erupt on the sea floor.

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Eventually they might become
islands like Pagan and Anatahan.

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[music]

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It is common for a chain of volcanic islands
like the Marianas to rise above the zone

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where crustal plates collide.
The chain typically forms

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along a curved line which is
called a Volcanic Island Arc.

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[sil.]

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In addition to volcanoes

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other parts of the seafloor are
pushed up where plates collide.

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When they rise to a depth just below sea
level coral reefs began to colonize.

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This reef grows offshore of Saipan,

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the capital of the
northern Mariana Islands.

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The sea floor underneath is being pushed up very
slowly and may eventually rise out of the sea.

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Saipan itself was lifted over
1,500 feet above sea level

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by the collision of the plates below it.

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Banzai and Suicide Cliffs dominate

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the north end of Saipan. They are the
uplifted remains of old coral colonies.

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A tragic incident occurred
here during World War II.

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Japanese forces lost a fierce battle
for Saipan to American forces.

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Rather than surrendering, thousands
of Japanese people committed suicide

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from these limestone cliffs.

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Peace memorials commemorate the tragedy.

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[sil.]

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On voyages to the Pacific Islands,

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scientists learned a great deal about Volcanic
Island Arcs like the Mariana Islands.

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When they returned to North America,

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they discovered that the rocks of Modern
Island Arcs are strikingly similar

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to ancient rocks in the Pacific Northwest.
For Tracy Vallier

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and his colleagues, the present
became the crucial link to the past.

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They could see firsthand how the older
rocks in the Hells Canyon area formed.

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Those folks who are out
there in the deep ocean

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hardly had any idea I suspect to being with that they were gonna be solving
problems on the continent, that were (inaudible) so complicated like

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what Tracy is working with. But
it did happened just that way

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and that\'s… that\'s the progress.

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[music]

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The research in the Pacific Ocean continued to
solve geologic mysteries in the Pacific Northwest.

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Geologists Ellen Bishop works in the
Greenhorn Mountain of Eastern Oregon.

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This area is known to geologists
as the Baker Terrane,

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which is named after Baker City, Oregon.

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For years geologists working in the Baker
Terrane could not explain how these rocks form.

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They are highly altered and mixed up
like no other rocks in the region.

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The mystery was solved when Ellen Bishop was doing
research at the Scripps Institution of Oceanography.

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My colleagues at Scripps

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were dredging the Marianas Trench looking
at ocean island systems of the Pacific

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and they kept coming home with the same
kinds of rocks that I was finding except

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I didn\'t have to use a ship and a dredge to find these
things. I just had to walk through the Greenhorn Mountains

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and I came up with the same mysterious assemblage
that they were finding in the South Pacific.

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Once again the present became
a crucial link to the past.

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Ellen Bishop concluded that the Baker Terrane
formed at an ancient subduction zone

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like the Marianas Trench.

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Her findings complimented the work of
geologists in the nearby Wallowa Terrane.

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When they put their data together,
they could see that the two terranes

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were part of the same Ancient Island Arc. The Wallowa
Terrane consisted of the volcanic islands and the arc.

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And the Baker Terrane was the
site of the subduction zone

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near the islands. The
entire geologic feature

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is called the Blue Mountains island Arc.

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[sil.]

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Fossil discoveries in the Wallowa Mountains

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hinted that the Blue Mountains Island
Arc was once an entire ocean away.

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I\'m standing at the ichthyosaur site. An
ichthyosaurs are swimming marine reptiles

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that lived on the age of the dinosaurs.
Uh… This particular ichthyosaur fossil

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with a skull discovered by a high school student very inadvertently
who stumbled upon it here on these shales ichthyosaurs.

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Like this are swimming reptiles but this particular
one is known from only one place in the world

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and that\'s in China and that supports the idea that
these rocks might have originated very far out

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in the Pacific far away from North America.

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A fossil find in Hells Canyon

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proved that the ancient islands migrated
far north from their tropical setting.

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Geologists Sydney, a professor
at Weber State University

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found the remains of an ancient forest
on the banks of the Snake River.

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The forest grew 175 million years ago

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and it looks something like today\'s forest.
It took about 35 million years

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at the rate of three inches
per year for the old islands

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to move to their new setting.
By modern comparison,

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the San Andreas Fault in California
moves about two inches per year.

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Los Angeles which is moving
north on the pacific plate

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will line up with San Francisco 380
miles away in about 12 million years.

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[sil.]

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Plate tectonic processes
like faulting and subduction

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caused the Blue Mountains Island
Arc to move across the ocean.

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By a 130-million years ago the islands were
close to the North American Continent.

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At that time, the West Coast
was located far inland

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from today\'s coast. Ocean waves
broke on beaches in Western Idaho.

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The Blue Mountains Island Arc was
one of many island groups offshore.

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Plate tectonics gradually closed the gap.

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About 115 million years ago

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the Blue Mountains are
docked with the continent.

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The collision occurred along a zone

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that passes close to Riggins
Idaho near Hells Canyon.

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Just east of Riggins just three or four miles,
we come to what\'s called the suture zone

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and you can think of it as… as a zipper or something
like that for that cotton has been zippered

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together with these oceanic islands.
The rocks of the sutures zone

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was squeezed and tilted during the
collision. The force was so great

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that the mountains of Central
Idaho were pushed higher

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by thousands of feet. For millions
of years after this suturing event,

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plate tectonics added new land
to Western North America,

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but one of the ancient islands
remains offshore today,

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it is known as Vancouver Island in Canada.

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[music]

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This is a land of misty fjords
and densely forested mountain,

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rugged cliffs rise to 7,000
feet above sea level.

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Pillow lavas make up many of these cliffs.

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Like the pillow lavas in Hells Canyon,
these rocks form under ocean water.

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High above the lavas a limestone cliff

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looks out on a valley. Pieces of limestone
are scattered all over the island.

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Many have fossils that
came from the tropics

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and some species are the same as
those in the Wallowa Terrane.

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Much of Vancouver Island
like the Wallowa Terrane

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formed in tropical waters
before plate tectonics

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moved it to its present position.

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The fossils of the Wallowa
Terrane have relatives

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even farther north than Vancouver Island.

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Fossil clamps here in the Wallowa Mountains
are also found in Northern Canada.

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In fact, many tropical fossils had
been collected as far north as Alaska.

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[sil.]

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Geologists search for more evidence to
support their exciting new findings.

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They used many types of
geologic investigations

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both in the field and in the lab.

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Paleomagnetism uses the magnetic properties of rocks
to determine their location when they first formed.

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Mass-spectrometry reveals
the kind of environment

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that rocks formed then
as well as their ages.

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A technique called potassium argon dating is
also used to determine the age of certain rocks.

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As scientists had hoped

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these studies provided supporting
evidence for their new geologic theories.

00:21:25.000 --> 00:21:29.999
It is now thought that much of
Western North America did not form

00:21:30.000 --> 00:21:34.999
as part of the continent.

00:21:35.000 --> 00:21:39.999
Large parts are made up of oceanic islands,
coral reefs and other seafloor fragments.

00:21:40.000 --> 00:21:44.999
These exotic terranes were
brought in from the ocean

00:21:45.000 --> 00:21:49.999
by the relentless force of plate tectonics.

00:21:50.000 --> 00:21:54.999
[music]

00:21:55.000 --> 00:21:59.999
Plate tectonics is still changing
the face of Western North America.

00:22:00.000 --> 00:22:04.999
Two crustal plates have collided just
offshore of Oregon and Washington,

00:22:05.000 --> 00:22:09.999
a subduction zone formed which
created a great chain of volcanoes

00:22:10.000 --> 00:22:14.999
are short distance from the coast.
These volcanoes like

00:22:15.000 --> 00:22:19.999
majestic Mount Rainier in Washington have produced
some of the most powerful eruptions on Earth.

00:22:20.000 --> 00:22:28.000
[sil.]

00:22:30.000 --> 00:22:34.999
Mount St. Helens unleashed its fury in 1980. The
landscape around the volcano was completely devastated.

00:22:35.000 --> 00:22:39.999
Terrane features including a dense forest

00:22:40.000 --> 00:22:44.999
were buried under thick layers of ash.
New vegetation is growing

00:22:45.000 --> 00:22:49.999
on a highly modified land surface.

00:22:50.000 --> 00:22:54.999
[sil.]

00:22:55.000 --> 00:22:59.999
Volcanic lava and ash buried most of the
exotic terranes in the Pacific Northwest.

00:23:00.000 --> 00:23:04.999
Great outpourings of lava called
the Columbia River Basalt

00:23:05.000 --> 00:23:09.999
flooded the region many times
for several million years.

00:23:10.000 --> 00:23:14.999
It may have looked something like this
volcanic landscape on the island of Hawaii.

00:23:15.000 --> 00:23:19.999
[sil.]

00:23:20.000 --> 00:23:24.999
The Snake River in Idaho was
just a minor stream there

00:23:25.000 --> 00:23:29.999
running gently over thousands of
feet of harden lava and other rocks.

00:23:30.000 --> 00:23:34.999
But powerful geologic forces allowed
the cutting of Hells Canyon

00:23:35.000 --> 00:23:39.999
in only two million years.
Geologically speaking,

00:23:40.000 --> 00:23:44.999
the canyon formed rather quickly. All
through the West geologic activity

00:23:45.000 --> 00:23:49.999
made dramatic changes in the landscape
in the past few million years.

00:23:50.000 --> 00:23:54.999
The exotic terranes of the Pacific Northwest look
nothing like they did when they first formed.

00:23:55.000 --> 00:23:59.999
Fortunately enough has been preserved
to reveal their fascinating past.

00:24:00.000 --> 00:24:04.999
[sil.]

00:24:05.000 --> 00:24:13.000
[music]

00:24:55.000 --> 00:24:59.999
Today, rugged mountains and deep canyons
dominate the exotic terranes of the West.

00:25:00.000 --> 00:25:04.999
Once buffeted by the waves
of tropical oceans,

00:25:05.000 --> 00:25:09.999
these rocks are now being
shattered by snow and ice.

00:25:10.000 --> 00:25:14.999
Being able to… to look at rocks from
the ocean floor here in the mountains,

00:25:15.000 --> 00:25:19.999
impresses me with the… the power and
consistent dynamics of this planet

00:25:20.000 --> 00:25:24.999
that it\'s something that it… it
keeps moving and keeps working

00:25:25.000 --> 00:25:29.999
and it\'s… it\'s not going to stop. Umm…
It\'s just going to keep on changing

00:25:30.000 --> 00:25:34.999
and… and… and working in (inaudible).

00:25:35.000 --> 00:25:39.999
[music]

00:25:40.000 --> 00:25:44.999
In addition to geology,
other forces of nature

00:25:45.000 --> 00:25:49.999
and people will change these exotic
terranes into something new.

00:25:50.000 --> 00:25:54.999
Eventually, the rocks will be eroded into
a river which will take them on a journey

00:25:55.000 --> 00:25:59.999
all the way to the sea,

00:26:00.000 --> 00:26:05.000
back to where they came from.

00:27:45.000 --> 00:27:49.999
This program was funded by the United States
Forest Service Department of Agriculture

00:27:50.000 --> 00:27:54.999
and the United States Geological
Survey, Department of Interior.

00:27:55.000 --> 00:28:00.000
[sil.]