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1. The Plate Tectonics Theory
A. Outer part of Earth is made of up __________ and ____________ pieces called
_____________, and these plates move ____________________and continually.
B. There are 4 main pieces of evidence for plate tectonics:
1. ____________________________________________= fit together like a puzzle
2. Similarity of _____________________________________found on India, Australia
and South Africa.
3. Similarity of _______________________________________found in South
America and Africa.
4. Paleomagnetism – where _________________________that contain _______record
Earth’s magnetic ______________________________at the time the rocks cooled.
C. The Earth consists of ____ major plates and ___________________ minor plates.
1. Each plate is about _______ km thick.
2. Plates move between ___________ cm per year.
3. The average plate speed is ______ cm/year.
D. Plate tectonics theory explains the _______________________ of mountain ranges,
volcanoes, and __________________________________.
2. Earth’s layers
A. Earth is composed of 3 main layers:
1. Core – Earth’s internal ________________________________. 2 sub-layers:
a. Inner core is made of solid iron and ______________.
b. Outer core is made of liquid _________.
c. Heat in the core caused from remnant heat from Earth’s _____________&
__________________________________________of elements.
2. Mantle – made of ____________________________ magma, 2 sub-layers:
a. ______________sphere = lower mantle, made of iron and
__________________________. The asthenosphere is semi-solid and can
flow like ___________ ___________.
b. ___________sphere = upper mantle and is rigid and stiff. Does
__________________!
c. Asthenosphere and Lithosphere separated by a change in
_______________ and rock _______________________. The boundary
between is called the ______________ discontinuity.
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3. Crust – is the outer skin of the earth. ____ types of crust:
a. Oceanic –thinner, ____________________, _______________ rock.
b. ______________________– thicker, __________ dense, granite rock.
B. Earth’s plates are made of either oceanic or continental crust and the
___________________. These tectonic plates “____________” on top of the plasticlike asthenosphere.
3. How Do Plates move?
A. Answer: _______________________ currents in the mantle.
B. Convection occurs when a liquid or gas is _______________, becomes _________ dense
and ____________. When it cools, it gets ___________ dense and sinks, and the process
_____________________.
C. This cycle of ___________________ and ____________________ drives plate motion.
D. Draw a simple convection current below.
4. Types of Plate Boundaries
A. There are 3 types of plate boundaries.
1. Convergent = when 2 plates ____________________ into each other. Features
such as mountains or subduction zones form. Draw a convergent plate boundary below.
2. Divergent = when 2 plates move __________ from each other. Volcanoes form at
divergent boundaries. Draw a divergent plate boundary below.
3. Transform = when 2 plates __________ past each other. Earthquakes happen at
transform boundaries. Draw a transform boundary below.
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5. More about plate boundaries
A. SUBDUCTION occurs when an oceanic plate (denser) is forced ______________ a
continental (lighter) plate.
1. At the subduction zone a ________________________________ is formed where the
plate is being forced downwards under the continental plate.
2. Subduction causes rocks to _____________, and magma _____________ to surface
to form _____________________.
3. Example: ____________________ in US, ________________ Mountains in South
America
B. Mountains can be formed when 2 ____________________ plates collide into each other.
1. Because they both have the same density, neither one subducts under the other. They
crumple together.
2. Classic examples are the _______________________, which are still going up at a
rate of __________cm/year.
C. When 2 plates move away from each other, magma _________ and _______ crust is
formed.
1. This is happening along the mid-Atlantic ridge, which passes through ____________.
2. If continental crust pulls apart from continental crust then the same process occurs.
As ______________ erupts to the surface to fill the gap, a ____________________ is
created.
D. When plates move past one another ___________________________ occur.
1. Plates are rigid so it is difficult for the plates to ________________ past each other.
2. The most famous conservative plate margin is the _______________________ Fault
on the western coast of North America.
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