Plate Tectonics
Chapter 17
Plate Tectonics
Continental Drift
_________
Wegener proposed
the theory that the
crustal plates are
moving over the
mantle. This was
supported by fossil
and rock type
evidence; also
matching of coastline
shapes.
Further evidence




Coal deposits in Antarctica indicate that it once
had swamp plants thriving
Climate was once tropical
Therefore, evidence to conclude that Antarctica
must have been closer to the equator
300 million years old glacial deposits show that
Africa, India, Australia, and South America were
once covered by ice cap similar to current
Antarctica. Found where it was warm therefore
must have been located near the south pole.
17.4 – Causes of Plate
Motion
Convection currents is the transfer od
thermal energy by the movement of
heated material from one place to
another.
 Like a lava lamp

Convection Currents
The force responsible for plate movement are convection
currents.
Plate Boundaries
The following two slides show maps of
the current major plate boundaries
and their relative motions.
 You should be able to describe
various landforms created by different
plate movements.

Plate Boundaries
apart
Divergent Boundary – moving _____
 Convergent Boundary – moving
________
together
 Transform Fault Boundary – moving
sideways past each other
________________________

Divergent boundary of two continental plates.
rift valley
East African Rift
Creates a __________.
Example: _____________
Convergent boundary of two oceanic plates.
island arc and a _____.
trench Example: _____
Japan
Creates an ________
Convergent boundary of an oceanic plate and a
continental plate. Forms a _______
volcanic mountain range
trench Examples: Cascades
Andes Mts
and a ______.
_______ or _______
Convergent boundary of two continental plates. Forms
Himalayas
a ______
folded mountain range. Examples: ___________,
Appalachians
Alps, ______________
Transform-fault boundary where the North American
and Pacific plates are moving ____
past each other.
San Andreas Fault in California
Example: ________________
Plate Boundaries Review





Places where plates move apart are called
_____________
boundaries.
divergent
When continental plates diverge a
rift valley
___________
is formed.
When two oceanic plates converge what is
an island arc and a trench
created? _________________
The Appalachians formed mainly from
continental plate collisions and therefore are a
__________
mountain range.
folded
Convection currents
The force moving the plates is ____________
.