Transcript Earth Science: Plate Tectonics

How do we see inside the Earth?
•
•
•
•
•
What do we use?
__________________________
Seismology
____________________________
What do we know that produces seismic
waves?
P-waves
“P” or Primary waves
–
–
–
–
_______________
_______________
_______________
Travel through all mediums ( solid, liquid
and air)
“S” Waves
• “S” or Secondary waves
–
–
–
–
_______________
Vibrate ____________/ ____________
_____________ than “P” waves
Only travel through _______________
The Crust
•
•
•
•
•
•
________ __________
Like an eggshell
___________
___________
Can crack
Two regions:
– ______________ (Basalt
rock)
– ______________ (granite
rock)
• Crust is _______ dense than
the mantle
• Like ice on water; the crust
_____________ on the mantle
The Mantle
• _____________
• Like the crust
– __________
– __________
• Iron, magnesium, calcium are heavier elements
• Mantle is ________ dense
• How does the Earth’s crust add to the density
of the mantle?
• __________ ___________ down on the
mantle…it compresses the minerals, increasing
the pressure and squeezing them into rocks.
The Mantle
•
•
•
•
Higher temperature
Why?
__________ __________
Decay of radioactive elements
Layers of The Mantle
• Upper mantle
• ___________
– Rigid rock upper
portion of upper
mantle
• ___________
– Lies beneath
lithosphere and
“__________” like
plastic
– It is ________…silly
putty
• Lower mantle
The Core
• ________ layers: inner and
outer core
• ____ Earth’s volume
• ____ Earth’s mass
• 2x as dense as the Earth’s
mantle
• Why?
• Made of _____ ______
• Inner core is VERY hot!
• Some places as hot as the
surface of the sun!
• ______ ______
The Inner Core
– How?
– __________ from
Earth keeps Iron
packed tightly;
doesn’t allow it’s
atoms to ______
The Outer Core
• Outer Core
– _______ Iron
– _______ pressure
– _____ and _____ as Earth rotates
– Creates _______ _________
– Affects Earth’s ________
– Produces _______ ______
– Possibly responsible for Earth’s magnetic field
Convection Currents
• What are
convection
currents?
• ________ of heat
flows from ______
to ______
• This sets up a
convection current
in the ________
Effects of Convection
Currents
• When the current comes at a weaker part of
the ________, for example at a _______,
________ comes above the earth's surface.
• This is called ______ _______.
• The movement of these plates goes very
slowly.
• The _______ of two tectonic plates causes
an _________.
• The ________ _______ along the bottom of
the _______ causes the moving of the
tectonic plates.
Continental Drift & Tectonic
Plates
• __________ Hypothesis on
Continental Drift
• The World’s continents are
in ________
• At one time, the continents
were ______ together as
one…
• This was known as _______
• They fit together like a
jigsaw puzzle
Continental Drift
• Wegner’s theory proposed the landmass
known as _______ started breaking up
• Separated into two parts: ______ and
________
• Wegner’s theory of the separation of
Pangea was supported by ______,
_________, _________ and
_________ evidence
Seafloor Spreading
• Seafloor is not _________
• Constantly _________ itself
• ____ ________ ______ (longest & tallest
mountain range in the world, center of the
________ Ocean)
• Forms ________: Iceland and Azore
• There are _______ in the mountains
Plate tectonics
• __________ move because they are
_________ in plates
• The plates shuffle or move _____ of
the Earth’s surface
• Plates move in _______ _______ and
different ______ from each other
• There are ______ large plates and
several smaller plates
Plate Boundaries
• _________ Boundaries
– Plates move
_____from each other
– Comes from rock in the
______________
– Partially melted
– The rock partially
melts = _______
– It was _____ before it
left the _______ of
the Earth
Convergent boundaries
• Plates move _______ each other
Transform fault boundaries
• Plates ______ ______ each other
Earthquakes
•
•
•
•
Devastating
______ (force) applied to _____
Stress causes ______
Eventually the rock cannot bend
anymore
• It breaks and releases ______
______
• The released energy ( ______ _____)
travel out in all directions
Earthquakes cont
• The initiating site of the
seismic wave: _______
• The point at Earth’s surface
directly above the focus:
________
• Measured on a _______
_______ ( the increments
are _____ fold in
magnitude…)
Tsunami
• Seismic sea wave
• Created by an
__________