ANTICIPATION GUIDE
1) All the continents once formed one supercontinent.
2) Continents drift across the molten mantle.
3) Divergent boundaries are where two plates come
together.
4) Volcanoes and earthquakes occur along plate
boundaries.
5) Mountains can form at transform boundaries.
Watch the video. Do you think one large
continent really existed?
Can you figure out how the
continents once fit together?
ALFRED WEGENER
Wegener was
Alfred ________
the scientist who
proposed the theory
Continental _____
Drift in
of __________
the early 20th century.
He proposed that
continents had once
__________
joined
been ________
together. He noticed
similarities between
continental coastlines.
EVIDENCE
Climate Clues
Fossil Clues
Evidence of continental
drift included _______
fossils that
were found on separate
continents, landform
shapes and features,
rock
identical ______
formations on separate
continents, and ________
climate
evidence. For example,
evidence of warmer
climates was found in
Antarctic fossils.
LITHOSPHERE
lithosphere is the
The _________
rigid outer layer of
____
the Earth. It is
made up of the
crust and upper
_____
mantle. It is broken
tectonic plates
into ________
that move slowly
upper
over the _____
mantle.
PANGAEA
The continents are
moving They
always ______.
move about two
centimeters
and half _________
each year. A
___________
supercontinent called
Pangaea existed
_______
about 250 million
years ago.
Pangaea
PLATES
lithosphere is broken into _____
eight
The _________
major plates and many minor ones.
CONVECTION CURRENTS
Tectonic ______
plates
on the planet’s
move
surface _____
because of
convection
_________
currents in the
mantle Hot
_______.
rises
material ____
and cool
sinks
material ____.
PLATE BOUNDARIES
Geologic activities occur
boundaries
along plate ____________.
Plate tectonics is responsible
for the creation of most
continental and ocean floor
features and for the
distribution of rocks and
minerals within the Earth’s
crust. Plate tectonics also
shapes our existing
continents and affects
seismic and volcanic activity.
three major types
There are _______
of plate boundaries.
CONVERGENT BOUNDARY
A convergent
__________ boundary is where two
plates are moving ________
towards each
other. Plates can push up to form
mountains or one can ___
slip below the
_________
other in what is called a __________
subduction
zone.
CONVERGENT BOUNDARY
One example, is where more
dense oceanic plates slide
under less dense continental
plates. An oceanic plate
forming a trench at a
subduction zone where crust is
melting and recycled is
another example. Along these
trenches, island arcs and
volcanic arcs can be created.
When two continental plates
collide, mountains are formed.
Earthquakes also occur as
these plates collide.
DIVERGENT BOUNDARY
A _________
divergent boundary is where two
plates are moving ______
away from each
crust is formed when
other. New ______
_______
magma rises to the surface between
two plates.
DIVERGENT BOUNDARY
Divergent boundaries create mid-ocean ridges and rift valleys.
New crust forms because magma pushes up and hardens in
the rift zone between separating plates. (seafloor spreading)
Volcanoes and other types of volcanic activity occur along
these boundaries. Earthquakes also occur as plates spread
apart.
TRANSFORM BOUNDARY
Transform boundaries are where two
_________
plates ______
slide sideways past each other.
friction and pressure builds, it can
As the ______
be released in the form of ____________.
earthquakes
TRANSFORM BOUNDARY
At a transform boundary, crust is neither created nor
destroyed. Earthquakes occur frequently as plates slide
past each other. The San Andreas Fault in California is
an example of a transform boundary.
San Andreas Fault
LET’S REVISIT
1) All the continents once formed one
supercontinent.
2) Continents drift across the molten
mantle.
3) Divergent boundaries are where two plates
come together.
4) Volcanoes and earthquakes occur along
plate boundaries.
5) Mountains can form at transform
boundaries.