Oregon Why is there a green side and a brown side of Oregon? Corvallis.

Oregon

Why is there a green side and a

brown side of Oregon?

Corvallis

Oregon

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Why are there Two Parallel Mountain Ranges in Oregon?

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The Whole Earth and Plate Tectonics

We need to understand know what goes on inside the Earth.

Depths in Miles

Oreo® Cookie

Oreo® Cookie

Oreo® Cookie

Oreo® Cookie

Oreo® Cookie

Oreo® Cookie

Oreo® Cookie

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Oreo® Psycho-Personality Test www.superkids.com/aweb/pages/humor/050199.sht

• Psychologists have discovered that the manner in which people eat Oreo® cookies provides great insight into their personalities. Choose which method best describes your favorite method of eating Oreos:

• 1. The whole thing at once.2. One bite at a time.3. Slow and methodical nibbles examining the results of each bite

afterwards.4. In little feverous nibbles.5. Dunked in some liquid (milk, coffee …..)6. Twisted apart, the inside, then the cookie.7. Twisted apart, the inside, and toss the cookie.8. Just the cookie, not the inside.9. I just like to lick them, not eat them.10. I don’t have a favorite way because I don’t like Oreos.

6. Twisted apart, the inside, then the cookie.

• You have a highly curious nature.• You take pleasure in breaking things apart

to find out how they work, though you’re not always able to put them back together, so you destroy all the evidence of your activities.

• You deny your involvement when things go wrong.

• You are a compulsive liar and exhibit deviant, if not criminal, behavior.

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Parks and Plates, ©2005 Robert J. Lillie

Sliding Plate over Asthenosphere

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Divergent Plate BoundaryParks and Plates©2005 Robert J. Lillie

North America

Africa

Atlantic Ocean

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North America

Africa

Iceland

Iceland

Pillow Basalt

Africa

SouthAmerica

Core

LowerMantle

AtlanticOcean

Asthenosphere

LithosphereTrench

Divergent Plate Boundary:

New Lithosphere Created

Mid-AtlanticRidge

Convergent Plate Boundary:Lithosphere Recycled back into

Deeper Mantle

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1New lithosphere created at divergent

plate boundaries. Does that mean Earth is expanding?

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Convergent Plate Boundary

Parks and Plates©2005 Robert J. Lillie

Subducting Plate Overriding

Plate

Deep-Sea Trench

Coast Range

Cascades

Subduction of the Juan de Fuca Plate forms the Coastal Ranges and Cascade Volcanoes

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Formation of the two parallel mountain ranges.

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Sedimentary layers scraped off the subducting plate form the Coast Range.

Mary’s PeakCorvallis,Oregon

Oregon StateUniversity

Mary’s Peak

Pillow Basalt – Coast Range Rocks made in the Ocean!

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Just like when you bicycle, the subducting plate sweats when it gets hot

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The rising hot water melts rock in its path, forming magma.

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Mount Hood and other Cascade Volcanoes form where some of the magma reaches the surface.

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Puget Sound and the Willamette Valley are low-lying regions between the rising mountains.

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Mt. St. Helens, Washington

Prior to 1980

Steep Composite

Volcano

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Early 1980

Bulge on North Side of

Mountain

Mt. St. Helens, Washington

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May 18, 1980

Explosive Eruption

Mt. St. Helens, Washington

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May 18, 1980

Mt. St. Helens, Washington

Eruption Cloud

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Mt. St. Helens National Volcanic Monument, Washington

200 + foot Douglas Fir trees downed on north side of mountain

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Mt. St. Helens National Volcanic Monument, Washington

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7,700 years ago – Southern Oregon’s Mt. Mazama was

perhaps taller than Mt. Hood.

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Vast amounts of volcanic ash, pumice, and lava flows erupted – the top of the mountain collapsed as rubble to fill the void, creating a

large crater.

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No rivers or creeks flow in or out of Mt. Mazama’s crater – rainfall and snowmelt partially fill it with some of the purest and

clearest water in the world

Crater Lake – 1,943 feet (592 meters) – deepest in the United States and 7th

deepest in the world!

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Later eruptions coated the crater floor – just like at Aniakchak Volcano in Alaska!

Volcano Inside a Volcano Lava Flows

Aniakchak National Monument, Alaska

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U.S. Geological Survey 3-D Image of Lake Bottom

Lava flows seal the bottom of Crater Lake

Volcano Inside a Volcano

Lava Flows

Wizard Island

Merriam Cone

Crater Lake Fly-Through Movie

Time: 0:57

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Wizard Island is a Cinder Cone Volcano formed after Mt. Mazama collapsed

Wizard Island

Oregon

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The Two Parallel Mountain Ranges make

the green and brown sides of Oregon

There are 20 potentially active volcanoes in the western United States (excluding Alaska and Hawaii).

Half are in the Cascades of Washington, Oregon, and northern California.

Cracked Egg Shell!Parks and Plates

©2005 Robert J. Lillie

Parks and Plates©2005 Robert J. Lillie

Plate Boundaries

San Andreas Fault

Western California is a Transform Plate Boundary

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Transform Plate Boundary Parks and Plates©2005 Robert J. Lillie

Pacific Plate

North American

Plate

San Andreas

Fault

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Parks and Plates©2005 Robert J. Lillie

Creating theSAN ANDREAS FAULT with a Deck of Cards

Pretend your left hand is the Pacific Plate, your right hand the North American Plate.

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Parks and Plates©2005 Robert J. Lillie

Creating theSAN ANDREAS FAULT with a Deck of Cards

The TRANSFORM PLATE BOUNDARY

is a broad zone of shearing between the

two plates.

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Parks and Plates©2005 Robert J. Lillie

Creating theSAN ANDREAS FAULT with a Deck of Cards

One card face eventually takes

over, simulating the predominance of

movement along the San Andreas Fault.

North American PlatePacific Plate

2 inches/year x 100 years= 200 inches

= 17 feet!

So in 100 years, a total of 17 feet (5 meters) of

movement would occur across the fault!

Orange Grove in Southern California – Planted 100 Years

Ago

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RT

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200

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Parks and Plates©2005 Robert J. Lillie

The San Andreas Fault and Gulf of California

accommodate transform plate motion

between the North American and Pacific

plates.

The San Andreas Fault accommodates

most of the transform plate

motion in California.

California Earthquake1973

Earthquakes

Parks and Plates©2005 Robert J. Lillie

Most earthquakes are at plate boundaries.

Parks and Plates©2005 Robert J. Lillie

Plate Boundaries

Where are the Volcanoes?

70% of them are in the "Ring of Fire"

Earth has more than 1500 active volcanoes

Turcotte, 1971

Plate Boundaries

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1. Where do Big Earthquakes occur?

Cascadia Subduction Zone2. Why do they occur there?

Plates stick together for about 300 years, then suddenly let go!

Boom!!!!

Parks and Plates©2005 Robert J. Lillie

Locked Zone Earthquake in the Pacific Northwest

Parks and Plates©2005 Robert J. Lillie

Locked Zone Earthquake in the Pacific Northwest

U.S.G.S.

What drowned these trees 300 years

ago?

Earthquakes from under the seasEarthquakes from under the seas Cause big waves to submerge the trees Cause big waves to submerge the trees The first waves are small The first waves are small Compared to them allCompared to them all These waves we call – These waves we call – tsunamistsunamis!

Generation of a TsunamiGeneration of a Tsunami

We can see what’s on the

surface.

Cascadia Subduction Zone

How does the surface change when the plates

are stuck?

How do we really know what’s

beneath here?

Drillhole across San Andreas Fault875 GPS Instruments175 Borehole Strainmeters5 Long-Baseline Laser Strainmeters400 Seismometers at 2,000 sites100 Permanent Seismometers

A project to:– Explore the structure and evolution of the North

American continent– Understand processes that cause earthquakes and

volcanic eruptions.

EarthScope

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