Plate Tectonics
What is Plate Tectonics?
According to the _______________________ theory, the
uppermost _________, along with the overlying _________,
behaves as a strong, rigid layer.
This layer is known as the _____________
A _________ is one of numerous rigid sections of the
_____________ that move as a unit over the material of the
_ _ _ __ _ _ _ _ _ _ _ _ _ _
Types of Plate Boundaries
__________________ (also called spreading centers) are the
place where two plates move apart.
 ___________________ form where two plates move together.
 _______________________ are margins where two plates
grind past each other without the production or destruction of
the lithosphere.
Divergent Boundaries
Oceanic Ridges and Seafloor Spreading
• ________________ are continuous elevated zones on the floor
of all major ocean basins. The rifts at the crest of ridges
represent divergent plate boundaries.
• _______________ are deep faulted structures found along the
axes of divergent plate boundaries. They can develop on the
s e a fl o o r o r o n l a n d .
• _____________________ produces new oceanic lithosphere.
Actions at Divergent Boundaries
CONTINENTAL RIFTS
• When spreading centers develop________________________,
the landmass may split into two
or more smaller segments, forming a _________.
Actions at Convergent Boundaries
A _______________ zone occurs when one oceanic plate is
forced down into the mantle beneath a second plate.
Oceanic-Continental
- _____________ oceanic slab sinks into the
__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .
- P oc k e t s o f m a g m a d e v e l o p a n d _ _ _ _ _ _ _
- __________________________ form in part by volcanic activity
caused by the _________________ of oceanic lithosphere
be n e a t h a c o n t i n e n t
• Examples include the Andes, _________, and the Sierra
Nevadas.
Actions at Convergent Plate Boundaries
OCEANIC – OCEANIC
Two oceanic slabs ___________ and one ___________ beneath
the other.
- This kind of boundary often forms ___________ on the ocean
floor.
- _______________ form as volcanoes emerge from the sea.
- Examples include the Aleutian, _____________, and Tonga
i s l ands .
Actions at Convergent Boundaries
CONTINENTAL-CONTINENTAL
When subducting plates contain continental material, two
c o n ti n e n ts _ _ _ _ _ _ _ _ _ _
This kind of boundary can produce new _____________, such as
the ____________.
Actions at Transform Boundaries
At a transform fault boundary, plates
__________________________________ without destroying
the lithosphere.
TRANSFORM FAULTS
• Most join two segments of a ____________________
• At the time of formation, they roughly parallel the direction of
pl a t e m o v e m e n t .
• They aid the movement of ________ crustal material.
Evidence for Plate Tectonics
Magnetic Pole Reversals
The mid-ocean ridge is a mountain range at the bottom of the
ocean that is composed mainly of volcanoes and lava flows. See
m ap p. 5 E S R T
The rocks created at the mid-ocean ridge have _____________
minerals that are aligned with Earth’s magnetic field.
Earth’s magnetic field ______________ on a cycle of thousands
of years.
Evidence of Plate Tectonics
The discovery of strips of ______________________, which lie
as mirror images across the ocean ridges, is among the
strongest evidence of seafloor spreading.
The data on the ages of seafloor sediment confirmed what the
_________________ hypothesis predicted.
The _____________ oceanic crust is at the ridge crest, and the
__________ oceanic crust is at the continental margins.
Evidence of Plate Tectonics
HOT SPOTS
A ___________ is a concentration of heat in the mantle capable
of producing magma, which rises to Earth’s surface; The Pacific
p l a te m o v e s o v e r a h o t s p o t, p r o d u c i n g th e
_ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Hot spot evidence supports that the _________ move over the
_ _ _ __ _ _ _ _ _ _ _ _ _ _ .
Causes of Plate Motion
________________________ WITHIN THE EARTH
Scientists generally agree that _________ occurring in the
mantle is the basic driving force for plate movement.
________________ is the motion of matter resulting from
changes in temperature
Mantle Convection
______________ are masses of hotter-than-normal mantle
material that ascend toward the surface, where they may lead to
igneous activity.
The ___________________________________ within Earth
causes the thermal convection in the mantle that ultimately drives
p l a te m o ti o n