Transcript Bob-Lillie-9-19-07

Oregon
Corvallis
Why is there a
green side and a
brown side of
Oregon?
Oregon
Why are there Two
Parallel Mountain
Ranges in Oregon?
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
®
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.
Sliding Plate over Asthenosphere
Parks and Plates, ©2005 Robert J. Lillie
North
America
Parks and Plates
©2005 Robert J. Lillie
Atlantic
Ocean
Africa
Divergent Plate Boundary
Iceland
North
America
Africa
Iceland
Pillow Basalt
New lithosphere created at divergent plate
boundaries. Does that mean Earth is expanding?
Mid-Atlantic
Ridge
Atlantic
Ocean
South
America
Divergent Plate
Boundary:
New Lithosphere
Created
Africa
Asthenosphere
Trench
Lithosphere
Lower
Mantle
Convergent
CorePlate Boundary:
Lithosphere Recycled back into
Deeper Mantle
Deep-Sea
Subducting Trench
Plate
Overriding
Plate
Parks and Plates
©2005 Robert J. Lillie
Convergent Plate Boundary
Coast Range
Cascades
Subduction of the Juan de
Fuca Plate forms the
Coastal Ranges and
Cascade Volcanoes
Formation of the two parallel mountain ranges.
Sedimentary layers scraped off the subducting plate form the
Coast Range.
Corvallis,
Oregon
Mary’s Peak
Oregon State
University
Pillow Basalt –
Coast Range Rocks
made in the Ocean!
Mary’s Peak
Just like when you bicycle, the subducting plate sweats
when it gets hot 
The rising hot water melts rock in its path, forming magma.
Mount Hood and other Cascade Volcanoes form where some of
the magma reaches the surface.
Puget Sound and the Willamette Valley are low-lying regions
between the rising mountains.
Mt. St. Helens, Washington
Steep
Composite
Volcano
Prior to 1980
Mt. St. Helens, Washington
Bulge on
North Side of
Mountain
Early 1980
Mt. St. Helens, Washington
Explosive
Eruption
May 18, 1980
Mt. St. Helens, Washington
Eruption
Cloud
May 18, 1980
Mt. St. Helens National Volcanic
Monument, Washington
200 + foot Douglas Fir trees
downed on north side of mountain
Mt. St. Helens National Volcanic
Monument, Washington
7,700 years ago –
Southern Oregon’s
Mt. Mazama was
perhaps taller than
Mt. Hood.
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.
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!
Later eruptions coated the crater floor – just
like at Aniakchak Volcano in Alaska!
Lava Flows
Volcano Inside
a Volcano 
Aniakchak National Monument, Alaska
Lava flows seal the bottom of Crater Lake
Volcano Inside
a Volcano 
Wizard
Island
Merriam
Cone
Lava
Flows
Crater Lake FlyThrough Movie
Time: 0:57
U.S. Geological Survey 3-D Image of Lake Bottom
Wizard Island is a Cinder Cone Volcano formed after
Mt. Mazama collapsed
Wizard
Island
Oregon
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
Western California is a Transform Plate Boundary
San Andreas
Fault
Plate Boundaries
Parks and Plates
©2005 Robert J. Lillie
San
Andreas
Pacific
Fault
Plate
North
American
Plate
Transform Plate Boundary
Parks and Plates
©2005 Robert J. Lillie
Creating the
SAN ANDREAS
FAULT with a
Deck of Cards
Pretend your left
hand is the Pacific
Plate, your right
hand the North
American Plate.
Parks and Plates
©2005 Robert J. Lillie
Creating the
SAN ANDREAS
FAULT with a
Deck of Cards
The TRANSFORM
PLATE BOUNDARY
is a broad zone of
shearing between the
two plates.
Parks and Plates
©2005 Robert J. Lillie
Creating the
SAN ANDREAS
FAULT with a
Deck of Cards
One card face
eventually takes
over, simulating the
predominance of
movement along the
San Andreas Fault.
Parks and Plates
©2005 Robert J. Lillie
So in 100 years, a total of
17 feet (5 meters) of
movement would occur
across the fault!
2 inches/year
x 100 years
= 200 inches
= 17 feet!
Orange Grove in Southern
California – Planted 100 Years Ago
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.
Parks and Plates
©2005 Robert J. Lillie
California Earthquake
1973
Earthquakes
Most earthquakes are at plate boundaries.
Parks and Plates
©2005 Robert J. Lillie
Plate Boundaries
Parks and Plates
©2005 Robert J. Lillie
Where are the Volcanoes?
Earth has more than 1500 active volcanoes
70% of
them are in
the "Ring of
Fire"
Turcotte, 1971
Plate Boundaries
Cascadia Subduction Zone
1. Where do Big Earthquakes
occur?
Plates stick together for about
300 years, then suddenly let go!
Boom!!!!
2. Why do they occur there?
Locked Zone Earthquake in the Pacific Northwest
Parks and Plates
©2005 Robert J. Lillie
Locked Zone Earthquake in the Pacific Northwest
Parks and Plates
©2005 Robert J. Lillie
What drowned these trees 300 years ago?
U.S.G.S.
Generation of a Tsunami
Earthquakes from under the seas
Cause big waves to submerge the trees
The first waves are small
Compared to them all
These waves we call – tsunamis! 
Cascadia Subduction Zone
We can see
what’s on the
surface.
How does the
surface change
when the plates
are stuck?
How do we really
know what’s
beneath here?
EarthScope
A project to:
– Explore the structure and evolution of the North
American continent
– Understand processes that cause earthquakes and
volcanic eruptions.
Drillhole across San Andreas Fault
875 GPS Instruments
175 Borehole Strainmeters
5 Long-Baseline Laser Strainmeters
400 Seismometers at 2,000 sites
100 Permanent Seismometers