Transcript tectonic plate boundaries

Tectonic Plates
Tectonic Plates
 The LITHOSPHERE, or Earth’s outer
layer, is broken up into huge pieces
plates
tectonic __________.
called _________
–These plates are continuously
moving
________.
 Let’s look at pg. 396
Answer this question…
 How do we know so much about the
mantle and the core?
– Seismic waves, or vibrations produced
from earthquakes, travel at different
speeds through the Earth. Their speed
depends on the density and composition
of the material they pass through.
– Traveling through a solid will go faster
than through a liquid.
Restless Continents
 Look at pg. 400!
Alfred
Wegener
 In the early 1900s, ___________ ___________
continental
wrote about his hypothesis of ____________
drift
______.
continents once
 Continental drift = the _____________
landmass
formed a single ______________,
then broke up,
and drifted to their current locations.
fossils
 Continental drift also explained why __________
of
the same plant and animal species are found on
continents that are on different sides of the Atlantic
Ocean.
Pangaea
 Wegener thought
that all of the
present continents
were once
joined
__________
in a
single, huge
continent called
Pangaea
______________.
 Pangaea is Greek
for
“all earth”
______________.
Events caused by
Earth’s
plate movement:
1. Sea-floor spreading
2. Mountain building
3. Earthquakes
4. Volcanoes
Mountain Building
Mountains
 ______________
exist because
tectonic plates are continually
moving
colliding
______________
and ___________
with one another.
Compression
tension
 ________________ or ____________
can form mountains in several ways.
3 types of mountains:
1. Folded Mountains:
squeezed
--Form when rock layers are _______________
upward
together and pushed ___________.
--Example: Appalachian Mountains
2. Fault-Block Mountains:
--Form when tectonic forces put
___________on
the Earth’s crust causing
tension
drop
down
large blocks to_________
_________.
--Example: Tetons in Wyoming
3. Volcanic Mountainsmagma
--Form when _________
rises to the Earth’s
surface and erupts.
– Example: Mount St. Helens
Earthquakes
 Most earthquakes take place near the edges of
tectonic
plates
__________
___________.
 As tectonic plates push, pull, or slip past each
other, stress increases along breaks in the Earth’s
faults
crust, or ___________.
 In response to this stress, rock in the plates
deforms
_______________.
Elastic
deformation
 __________
_______________:
Imagine a
stretched rubber band. You can only stretch rock
so far before it breaks. When the rock breaks, it
energy
releases ________________.
Sea-Floor Spreading
 Process by which new oceanic
________________
forms as __________
lithosphere
magma
rises toward the surface and solidifies.
mid-ocean
ridges
 Occurs at ____________
__________,
or
underwater mountain chains
tectonic
plates
 As ___________
__________
move away
from each other, the sea floor spreads apart
and magma fills the gap.
Look at page 402…
Figure 3: Sea-Floor
Spreading
Volcanoes
tectonic ______
plate _________.
boundaries
 Likely to form at _________
The
Ring
of
Fire
 ________
_________
_____
_________,
plate
boundaries surrounding the Pacific Ocean,
75% of the world’s active
contains nearly _____
volcanoes.
80% of active volcanoes on land form
 About _____
15%
collide
where plates ______________,
and about ______
separate
form where plates ____________.
 At these plate boundaries it is possible for
magma
_____________
to form and travel to the surface.
The Ring of Fire
3 Types of Boundaries…
 Look at pg. 404-405
1. Convergent Boundaries:
--Formed when two tectonic
plates __________
COLLIDE
a. Continental-Continental Collisions
b. Continental-Oceanic Collisions
c. Oceanic-Oceanic Collisions
2. Divergent Boundaries:
--Formed when two tectonic plates
SEPARATE
____________
3. Transform Boundaries:
--Formed when two tectonic plates
SLIDE past each other horizontally
________