Chapter 4: PLATE TECTONICS
Learning Target
Vocabulary Word
Definition
Facts or Examples
continental
drift
continents slowly moved
over Earth’s surface
Wegener’s hypothesis
was that all the
continents were once
joined together in a
single landmass and
have since drifted
apart.
Pangaea
a supercontinent, or
single landmass, where
all the continents were
joined together
Pangaea existed about
350 million years ago
and over tens of millions
broke apart and drifted.
fossil
any trace of an ancient
organism that has been
preserved in rock
Ex. Glossopteris – fernlike
plant, 250 mya found in
Africa, S.A., Australia,
India, & Antarctica
evidence for
Continental Drift Theory
Lesson 1
I can explain Alfred
Wegener’s
hypothesis about the
continents, evidence
supporting the
hypothesis, and why
the hypothesis was
rejected . . .
Lesson 2
Symbol/Picture
I can define and
describe mid-ocean
ridges . . .
mid-ocean
ridge
long chains of
mountains that rise up
from the ocean floor
Mid-ocean ridges are
mapped using sonar
(sound waves).
I can explain how
sea-floor spreading
affects Earth’s
crust . . .
sea-floor
spreading
at mid-ocean ridges,
new material is
continually added to
the ocean floor
As sea-floor spreading
adds new more crust to
the ocean floor, older
strips of rock move
outward from either side
of the ridge.
I can explain deepocean trenches and
the process of
subduction . . .
deep ocean
trenches
the oceanic crust bends
downward
In a process that takes
tens of millions of years,
part of the ocean floor
sinks back into the
mantle at deep ocean
trenches.
subduction
the process by which
the ocean floor sinks
beneath a deep ocean
trench and back into
the mantle again
As subduction occurs,
crust closer to the midocean ridge moves
away from the ridge
and toward a deepocean trench.
Lesson 3
I can explain the
theory of plate
tectonics . . .
The major tectonic
plates are: North
American, South
American, Pacific,
African, Eurasian,
Antarctic, IndoAustralian, Nazca,
Scotia, Phillippine,
Cocos, Arabian,
Caribbean, & the Juan
de Fuca plates.
plate
pieces of Earth’s
Lithosphere
divergent
boundary
where two plates move
apart from each other
Most occur along midocean ridge, can also
cause rift valleys.
where two tectonic
plates come together
Two continental plates,
two ocean plates or
one continental and
one oceanic that
collide can cause
mountains or
subduction.
convergent
boundary
transform
boundary
where two plates slip
past each other
North Amerian – Pacific
plates (by California),
many earthquakes can
occur at this boundary.
plate tectonics
theory that states that
Earth’s plates are in
slow, constant motion,
driven by convection
currents in the mantle
This theory incorporates
sea-floor spreading,
continental drift and
fossils as evidence.
faults
breaks in Earth’s crust
where rocks have
slipped past each other
Occurs at plate
boundaries. Plates can
collide, pull apart or
grind past each other.
rift valley
a deep valley that forms
when plates pull apart
or diverge on land
Ex, East African rift
system
Learning Targets Chapter 4
Lesson 1
I can explain Alfred Wegener’s hypothesis about the continents, evidence supporting the hypothesis, and why the
hypothesis was rejected . . .
Wegener’s hypothesis was that all the ___________________ were once joined together in a _______________ landmass, called
__________________ and have since __________ apart.
Lesson 2
Mid-ocean _______________ form long chains of __________________ that rise up from the ocean floor.
I can explain how sea-floor spreading affects Earth’s crust . . .
Sea-floor spreading adds more ____________ to the ocean floor. At the same time, older strips of rock move
_________________ from either side of the _____________.
I can explain deep-ocean trenches and the process of subduction . . .
In a process taking tens of millions of years, part of the ocean floor _______________ back into the _______________ at deepocean ridges.
Lesson 3
I can explain the theory of plate tectonics . . .
The Theory of Plate Tectonics states that Earth’s _____________ are in slow, ________________ motion, driven by ____________
currents in the ____________________.