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Study Guide - Chapter 7 Plate Tectonics
Section 1: Inside the Earth
Study and know the Composition Layers of the Earth (Crust, Mantle, Core) –from the Earth model we made in class. These
layers are based on areas of similar composition (the elements that are present). Need to know their order from outside in,
Thickness, Temperature, Composition and State. (p. 190)
Know how Earth’s layers are further grouped into 5 Physical Layer (“Spheres”) based on their Physical properties (solid,
liquid, plastic solid). Know their order from outside-in, important features: (p. 192)

Lithosphere – made up of the
plates are located.

Asthenosphere – the “plastic” layer of the

Mesosphere – the strong, lower part of the

Outer Core – this layer is in a liquid

Inner Core – this layer is in a
crust
solid
and upper part of the
mantle
mantle
mantle
on which the tectonic
. This is where
plates
.
state
state
Use the following terms to label the diagram below. Terms may be used more than once.
crust
mantle
outer core
inner core
tectonic plate
astenosphere
mesosphere
move.
tectonic
Study Guide - Chapter 7 Plate Tectonics
Section 2: Restless Continents
What is Continental Drift and who came up with the idea? (p. 198)
Continental Drift is the hypothesis that states that the continents once formed a single landmass, broke up,
and drifted to their present locations. A scientist named Alfred Wegener came up with the theory in the early
1900’s.
What is Pangea? (p. 199)
Pangea was a single, huge continent formed when all the present continents were joined in one huge, single
continent . We now know from the hypothesis of plate tectonics that Pangaea existed about 245 million years
ago.
Use the two terms below to explain how we know the Continents/Tectonic Plates move: (p. 198, 205)
Fossils
GPS
Continental drift explains why fossils of the same plant and animal species are found on continents that are on
different sides of the Atlantic Ocean. Many of these ancient species could not have crossed the Atlantic Ocean.
Scientists use a system of satellites called the global positioning system (GPS), to measure the rate of tectonic
plate movement. Radio signals are continuously beamed from satellites to GPS ground stations, which record
the exact distance between the satellites and the ground station. Over time, these distances change slightly.
By recording the time it takes for the GPS ground stations to move a given distance, scientists can measure the
speed at which each tectonic plate moves.
What happens when plates separate on the sea floor and what evidence do we have that this takes place? (p. 200, 201)
Mid-ocean ridges are places where sea-floor spreading takes place. Sea-floor spreading is the process by
which new oceanic lithosphere forms as magma rises toward the surface and solidifies. Some of the most
important evidence of sea-floor spreading comes from magnetic reversals recorded in the ocean floor.
Which is older, rock that is close to the mid-ocean ridge or rock that is far away from the mid-ocean ridge? (p. 200)
Older rock is far away from the mid-ocean ridge. Younger rock is formed at the mid-ocean ridge.
Section 3: The Theory of Platae Tectonics
What does the theory of Plate Tectonics say? (p. 202)
Plate Tectonics is the theory that the Earth’s lithosphere is divided into tectonic plates that move around on
top of the asthenosphere.
Study Guide - Chapter 7 Plate Tectonics
What might be the cause of the movement of tectonic plates? (p. 204)
This movement occurs because of changes in density within the asthenosphere. These density changes are
caused by the outward flow of thermal energy from deep within the Earth. When rock is heated, it expands,
becomes less dense, and tends to rise to the surface of the Earth. As the rock gets near the surface, the rock
cools, becomes more dense, and tends to sink. This is called convection.
What do tectonic plates consist of? (p. 195)
Tectonic plates consist of continental crust and oceanic crust.
Describe the types of Boundaries that exist between plates, what causes the boundaries and what the results are: (p.
203)
Boundary
Formed by Plates doing what?
Convergant
Coming together
What is the Result?
Mountains, Subduction (when ocean crust
goes under continental crust and is melted)
Divergant
Moving Apart
Mid-Ocean Ridges – magma rises up
through the cracks and forms new crust
Transform
Sliding Past Each Other
Faults/Earthquakes
Section 4: Deforming the Earth’s Crust
What is stress? (p. 206)
Stress is the amount of force per unit area on a given material.
What causes rocks to deform? (p. 206)
The shape of a rock changes because of stress. Stress is the amount of force per unit area on a given material.
What are the two possible results of deformation? (p. 206)
Bending
When rocks are
SQUEEZED
or
we call this
Breaking
Compression
When rocks are –STRETCHED- we call this
Tension
(p. 206)
(p. 206)
Study Guide - Chapter 7 Plate Tectonics
What is folding? (p. 207)
The bending of rock layers because of stress in the Earth’s crust
What is faulting? (p. 208)
The breaking of rock layers because of stress in the Earth’s crust
Know the different types of deformations, what the cause is and an example of this type of deformation: (p. 207-211):
Type of Deformation
(fault)- Normal
Cause
Tension that pulls rocks apart
Example
Fault-Block Mountains Tetons
(fault)- Reverse
Compression that pushes rocks together
Folded Mountains (examples
below)
(fault)- Strike-Slip
opposing forces cause rock to break and
Faults - San Andreas Fault
move horizontally
Fold
rock layers are squeezed together causing
them to bend
Folded Mountains –
Appalachian, Alps, Ural,
Himalayas