Download Seafloor Spreading

Seafloor Spreading
Ocean floor moves like a ___________________________ carrying continents with it.
__________________ ocean floor forms along cracks in the ocean crust as molten
material erupts from the mantle spreading out and pushing ________________ rocks to
the sides of the crack. New ocean floor is constantly added by the process of
______________________________.
Evidence of Seafloor Spreading
1. _______________________________________ – Rocks shaped like pillows (rock pillows)
show that molten material has erupted again and again from cracks along the mid-ocean ridge and
cooled quickly.
The _____________________________ the most extensive chain of mountains on earth,
but more than ________________ of this mountain range lies in the deep ocean. The midocean ridge wraps around the globe for more than 65,000 km like the seam of a baseball.
2. ____________________________ – Rocks that make up the ocean floor lie in a pattern of
magnetized stripes which hold a record of the reversals in Earth’s magnetic field
3. _____________________________ – Core samples from the ocean floor show that older rocks
are found farther from the ridge; youngest rocks are in the center of the ridge
Sea-Floor Spreading – ________________________in the 1960’s; the process that continually
adds new material to the ocean floor while pushing older rocks away from the ridge.
Plate Tectonics
According to the theory of plate tectonics, the earth’s outer shell is not one solid piece of
rock. Instead the earth’s crust is broken into a number of _____________________. The
plates vary in size and thickness.
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These plates are not anchored in place but __________________over a hot and bendable
layer of the _____________________.
Tectonic Plates
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
These tectonic plates are ___________________________________.
There are 3 types of plates
Divergent:
Convergent:
Transform:
Plate Boundaries
Divergent Boundary:  

Boundary between two plates that are _________________________________.

Features of Divergent Boundaries are:
Convergent Boundaries: 
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Boundaries between two plates that are ___________________.
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Three Types
Ocean to Continent: Ocean plate collides with Continent Plate
Subduction Zones:
Volcanoes
Ocean Plates are more ______________ than the Continent plates
Ocean to Ocean: Ocean plate collides with another ocean plate
The ____________ dense plate slides under the __________ dense plate creating a subduction
zone creating a ______________________.
Island arcs are formed
Continent to Continent
Plates push _________________________ forming ________________________.
Transform Boundaries: ↓↑

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Boundaries between plates that ______________________ past one another.
___________________________ occur at this boundary.
What’s the most active transform boundary in the U.S.?
__________________________________.