The Restless Earth
The Crust
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Outermost layer
___________________ layer
Ranges from 5-100km thick
Also known as the __________________________, which contains the
_______________ and the __________________________________________
Continental Crust
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Contains all known life in the universe
Consists mostly of ___________________________________
Ranges from 6 to 47 miles thick (average _________________)
Surface lies mostly above sea level
Makes up about 70% of the crust
_________________ than oceanic crust
Oceanic Crust
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Found under the ocean floor
Made up of ____________________________________
Only _____________________ thick
Much __________________
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Much ____________________ than continental crust and is constantly
________________ under it, eventually reaching the ______________________
Continental vs. Oceanic Crust
Continental
___________________
___________________
___________________
___________________
Oceanic
___________________
___________________
___________________
___________________
The Mantle
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Contains most of the Earth’s mass (67%)
_______________________ that moves by _______________________
No one has ever seen it because it is too far down and hot to drill for samples
Underwater volcanoes give us clues about it’s composition
The Core
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_________________________ is liquid layer below the mantle
_________________________ is solid, dense, and under extreme pressure
found in the center of the Earth
Composed mainly of __________________
The Mantle’s Physical Layers
__________________________
Crust + rigid upper part of mantle
Divided into pieces called tectonic plates
__________________________
Soft mantle layer where the lithosphere floats
Made of solid rock that flows very slowly like putty
“weak sphere”
__________________________
Under asthenosphere
More pressure = more dense
“middle sphere”
Mapping Earth’s Interior
How do we know about all these things about the deepest part of the Earth?
_________________________
Vibrations called _________________________ are produced during earthquakes.
These waves travel through the Earth.
Depending on the _________________ and ____________________ of material they
pass through, seismic waves travel at different speeds.
Seismic Waves
Seismic waves traveling through _________________________________________ than
a seismic wave traveling through a___________________________.
Body Waves: ____________________________________________________________
Tectonic Plates
Giant pieces of the Earth’s crust that fit together and move around on the Earth’s
surface are called _____________________________________.
There are 7-10 large primary plates and many smaller plates.
Seafloor Spreading
New oceanic crust is created as large slabs of the Earth's crust _____________________
from each other and _________________ wells up to fill the gap.
As they slowly move _____________________ from each other beneath the ocean
floor, hot magma from the Earth’s mantle bubbles to the surface.
This magma is then cooled by seawater. The new rock forms a new part of the Earth’s
crust. Seafloor spreading occurs along ________________________________________
_______________________________________________________________________.
The Mid-Atlantic Ridge
_________________________ between two tectonic plates in the Atlantic Ocean
Magma from the mantle reaches the seafloor, erupting as _____________________
Produces __________________________ for the plates
Ridge spreads at an average rate of __________________________
Continental Drift
____________________________ wrote his theory of continental drift
Believed that the ___________________ fitting of the continents was not a coincidence
Suggested that continents were once _______________________________at some
point in the past
This large supercontinent was named __________________________and it broke apart
about 200 million years ago
Dinosaur Fossil Evidence
Fossils of the reptile Mesosaurus have been found in South America & Africa
The Mesosaurus was a swimming reptile that lived in freshwater and on land, but it is
______________________________________________________________________
______________________________________________________________________
Plant Fossil Evidence
Fossils of the extinct plant, Glossopteris
An extinct fern that grew in thick strands all across the southern half of Pangaea
Presence of the fern in so many areas led Wegener to believe that all these
________________________________________________________________________
________________________________________________________________________
Climate Evidence
Fossils of warm weather plants native to tropical regions have been found in the Arctic
Ocean.
_______________________________________________________ found in South
America, Africa, India and Australia show these continents were once covered by
glaciers.
How can you explain why glacial deposits
are found where there are none today?
Rock Evidence
If continents were connected at one time, then rocks that make up the continent should
be the same.
________________________________________________________________________
________________________________________________________________________
Parts of the Appalachian Mountains, Greenland, Europe, and Africa are similar
Explanation, please?
Most people thought Wegener was nuts until the 1960’s when ____________________
proposed the accepted theory known as _____________________________.
Seafloor spreading helped provide an explanation of how the continents could move
Seafloor Spreading
________________________________________________________________________
________________________________________________________________________
As tectonic plates move away from each other, the sea floor spreads apart and magma
rises to fill the gap
Mid-ocean ridges form underwater range that stretches along the center of much of
Earth’s floor
In 1968, scientists aboard the research ship Glomar Challenger drilled into the seafloor
to obtain rock samples.
They found no rocks were older than 180 million years.
In contrast, some continental rocks are almost 4 BILLION years old!
Draw a diagram that explains the theory of Seafloor Spreading
Oceanic crust
Continental crust
Magma
Mantle
Lithosphere
Ocean
Youngest
Oldest
Mid-Atlantic Ridge
Convection currents
*Arrows that show direction of
seafloor movement
Magnetic Clues
Earth’s north and south __________________________________________________
many times over a course of thousands or even millions of years.
When this occurs, it is called a ____________________________________________
___________________-bearing minerals are found in ________________________.
These minerals act like a ______________________________ and align with the Earth’s
magnetic fields.
Once the rock cools, the direction is literally “set in stone.”
New bands start when a ____________________________ takes place.
Possible Causes of Tectonic Plate Motion
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Hot material from deep within Earth rises while cooler material near the surface sinks.
When the warmer material cools, it becomes denser and sinks back down. The motion
of convecting mantle drags tectonic plates sideways.
___________________________________
At mid-ocean ridges, the oceanic lithosphere is higher than it is where it sinks beneath
continental lithosphere. Ridge push is the process by which an oceanic plate slides
down the lithosphere-asthenosphere boundary.
____________________________________
Because oceanic lithosphere is denser than the asthenosphere, the edge of the oceanic
plate sinks and pulls the rest of the tectonic plate with it in a process called slab pull.
Tectonic Plate Boundaries
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Two tectonic plates _______________________ into each other
_______________________________________________ – buckle, thicken, and push
crust upward (mountain)
________________________________ – Oceanic slides under continental creating a
_______________________________where the plate sinks and down into the
asthenosphere
________________________________ – One slides under the other, much like the
continental/oceanic collision
In other words…
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Convergent boundaries happen when plates collide into one another.
Either mountains or subduction zones will be created.
Subduction zones are where the Earth is “eating” itself. One plate is sinking back
down into the mantle and will melt again.
________________________________
Two tectonic plates _________________ _________ from each other
__________________________________ – where new oceanic crust forms because of
rising magma that fills the gap
________________________________
Occurs when two tectonic plates ______________________ each other horizontally
The _____________________________________ in southern California marks the
boundary where the Pacific plate and North Amercian Plate Slide past each other