Plate Tectonics PPT Notes
Name_________________________
4 Main Layers of the Earth
1) Crust – Made up of two types: _________ and __________.
Contains mostly ________, Oxygen, and Aluminum
2) Mantle – Divided into _______ and lower mantle; mostly _____ and magnesium
3) Outer Core – ________; Mostly Iron and _________
4) Inner Core – ________; Mostly Iron and Nickel
Comparison of Earth’s Two Types of Crust
1) Oceanic ________ and more dense
Made up mostly of mafic (basaltic) igneous rocks _________ and ___________
2) ContinentalThicker and ______ dense
Made up mostly of the felsic (granitic) igneous rocks _________ and __________
CHAPTER 10 -- PLATE TECTONICS
(rev. 1/05)
I. Theory of Continental Drift - proposed by _________ ____________.
The theory states that the continents have ________ ___________ to their
present location.
Evidence for the theory:
A) Continents’ shorelines fit like a puzzle.
Wegener called this large landmass ____________
(see fig.1 and 4, pp. 272, 275)
B) Fossils:
Fossils of similar animals such as ____________ (a reptile)
and _______________ (a fern) were found on different continents
(see fig.2 on page 273)
C) Climate:
1) Warm-weather fossils found in the __________.
2) Evidence of ___________ found in present-day warm areas of
South America, Africa, India, and Australia.
D) Rock type and structures:
Similar rock types and rock structures are found on different
continents. Example: The Appalachian folded mountains in
the United States match the pattern of rocks in Greenland
and _________ __________.
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Block___
II. Theory of Seafloor Spreading -- proposed by _________ _________.
• The theory states that hot, less dense material in the mantle is forced upward
to the surface at the ______-________ ridges.
• As magma is forced upward at mid-ocean ridges, it flows in ________ directions
away from the ridge.
• As it moves away from the ridge, the magma cools, solidifies, gets ________and becomes ______ dense.
• Becoming more dense than the ______________ below it, the oceanic crust sinks downward at convergent
boundaries, forming ____________
Evidence for the theory:
A) Age of the Seafloor
• Oceanic crust is _______ than continental crust
• Oceanic crust is ____ million years old while continental crust is almost ____ billion years old.
• Rocks are younger at the __-_____ _____ and get increasingly ______ away from the ridge on both sides. (see
fig. 5, p.276, and graph on p. 279)
B) Magnetic Clues
• ________ minerals in basaltic rocks align with the Earth’s _________ field.
• The magnetic field has ___________ several times.
• The reversal creates an ____________ pattern of normal and reversed polarity that is _____ _______ on both
sides of the ridge (see fig.7, p.278).
III. The Theory of Plate Tectonics
This theory helps explain continental ______, seafloor _________, AND provides
a cause for these movements of the crust. The cause was what was lacking
in the previous theories. The theory of plate tectonics states that the
Earth’s continental and oceanic crust is broken up into sections. These
sections are called __________ or ____________ plates, and they move over the
surface of the Earth. The larger plates and their boundaries can be seen
in figure 9, page 281.
Layers Related to Plate Tectonics:
1) Lithosphere
• Consists of the _____ and rigid upper _____
• Broken into large pieces called ______ ________.
2) Asthenosphere
• ___________-like part of the upper mantle.
• Is beneath the _______________.
As the tectonic (lithospheric) plates move along and above the asthenosphere, the plates meet at three (3) types of
boundaries: Divergent, _____________, and Transform.
A. DIVERGENT BOUNDARIES
-- The tectonic plates are moving ________ _______ each other.
-- Characteristics of a divergent plate boundary are:
1) ______________
2) _____________ since the molten material of the
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mantle is so close to the surface.
-- Examples of divergent boundaries are the Mid-Atlantic _______ and the
East-African _______ _____________.
Sketch a cross-section view of a divergent boundary in the space below:
B. CONVERGENT BOUNDARIES
-- Plates move ____________ each other
-- There are three (3) types of convergent plate boundaries:
1) Oceanic-to-Continental
-- The more dense __________ crust ___________under the
less dense _____________ crust.
-- Characteristics of this type convergent boundary are:
a) ____________ at subduction zone
b) Volcanoes
c) ________________
-- An example of this type boundary is the _____________
Mountains on the west coast of South America.
Sketch a cross-section view of an oceanic-to-continental convergent boundary in the space below:
2) Oceanic-to-Oceanic
-- An _________, cooler, and ______ dense oceanic plate ___________
under another oceanic plate.
-- Characteristics of this type of convergent plate boundary are:
a) Volcanic __________ _______
b) Earthquakes and ___________
c) Ocean or narrow seas on _______ _______ of the boundary
-- Examples of this type of boundary are _________ and the
____________ _____________ in Alaska
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Sketch a cross-section view of an oceanic-to-oceanic convergent boundary in the space below:
3) Continental-to-Continental
-- This occurs when _______-dense _______________-crust plates
collide. Being ______ dense, these plates can only
move __________ during collision.
-- Characteristics of this type of convergent boundaries are:
a) Tall mountains
b) Earthquakes
c) ____________ of _____________ because there is
no ______________.
-- The _______________ mountains where ________ and ________
collided are an example.
Sketch a cross-section view of a continental-to-continental convergent boundary in the space below:
C) TRANSFORM BOUNDARIES
-- At this boundary, the tectonic plates _______ _______ each other
with little or ___ __________ movement or subduction. The
movement is in opposite directions, or in the same direction
at different rates (See figure 11 on page 284)
-- Characteristics of a transform boundary:
1) ____________ Earthquakes
2) An ___________ of volcanoes since there is ____ subduction
-- An example of a transform boundary is the _____ ___________
Fault in California.
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Sketch a cross-section view of a transform fault boundary in the space below:
THE FIGURE ABOVE SHOWS A SUMMARY OF PLATE BOUNDARY TYPES.
Identify and label the plate boundaries shown.
One type of plate boundary is not shown in this figure; Which type is not shown?
(Theory of Plate Tectonics Continued)
D) General characteristics related to plate tectonics:
-- Volcanoes and Earthquakes are concentrated along
________ ______________. An example is the “Ring of _______”
in the Pacific Ocean. (See figures 2 on page 301
and 5 on page 333)
-- An exception to earthquakes and volcanoes being
along plate boundaries is the occurrence of _____ ________
where the mantle material is very close to the
surface in isolated areas __________ a plate (see figure
8 on p.335). An example of a ____ _______ is ___________.
-- The cause of tectonic (lithospheric) plate movement is __________
_________ in the plastic-like mantle, or the _____________
-- There are different _________ made to explain these _____________
___________________.
.
(See figure 12 on p. 285)
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