Transcript Movements of Earth`s Major Plates PPT

Bell Work: 11/1/11
Please write the question,
answer, and explain why you
chose that answer (justify).
Objectives
• Differentiate among the
characteristics of the earth’s
three layers. (SPI 0707.7.4)
• Recognize that lithospheric
plates on the scale of continents
and oceans continually move at
rates of centimeters per year.
(SPI 0707.7.5)
Think, Pair, Share …
Come up with an explanation to
the following question, pair up
with your elbow partner, &
share:
• How do we know so
much about the mantle
and the core?
From our discussion…
• 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!
• In the early 1900s, ___________
Wegener
Alfred ___________
wrote about his hypothesis of continental
____________
______.
drift
• Continental drift is the hypothesis that
states that the _____________
continents once formed
a single ______________,
broke up, and
landmass
drifted to their present locations.
• Continental drift also explained why
__________
fossils 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”
You try it!
Make Pangaea with the
pieces of continents at
your group.
Challenging Question…
Think, Pair, Share …
• Based on what you know about
tectonic plates, how would you
prove Wegener’s theory to be
true?
Tracking Tectonic
Plate Motion
• Scientist use a system of satellites
called global positioning system or
GPS.
• Radio signals are continuously
beamed from satellites to GPS
ground stations, which record the
exact distance between the
satellites and the ground stations.
• Over time, these distances change
slightly.
• The movement is measured in
centimeters per year.
Events associated with
movements of earth’s major
plates:
•
•
•
•
Sea-floor spreading
Mountain building
Earthquakes
Volcanoes
Sea-Floor Spreading
• ____________
Mid-ocean __________,
ridges or underwater
mountain chains, are where
Sea-floor spreading
____________
___________ takes place.
• Sea-floor spreading is the process by
(or crust)
which new oceanic Lithosphere
____________________
magma rises toward the
forms as __________
surface and solidifies.
• As ___________
tectonic __________
plates move away
from each other, the sea floor spreads
apart and magma fills the gap.
Draw a picture of the sea floor spreading.
Mountain Building
• ______________
Mountains exist because tectonic
plates are continually ______________
moving
around and ___________
colliding with one another.
• The Andes Mountains in South America
formed where two tectonic plates
converge or collide.
• When tectonic plates undergo
________________ or ____________,
tension they can
compression
form mountains in several ways.
3 types of mountains
• Folded Mountains- form when rock layers
are _______________
together and pushed
squeezed
___________.
upward
Draw a picture
• Example: Appalachian Mountains
• Fault-Block Mountains- form when tectonic
forces put ___________on
the Earth’s crust
tension
causing large blocks of the Earth’s crust
to_________
_________.
drop
down
Draw a picture pg. 413
• Example: Tetons in Wyoming
• Volcanic Mountains- form when _________
magma
rises to the Earth’s surface and erupts.
• Most of the world’s major volcanic mountains
are located at convergent boundaries where
oceanic crust sinks into the asthenosphere at
subduction zones
• Example: Mount St. Helens Draw a picture
Earthquakes
• The study of earthquakes is called
________________.
seismology
• 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 crust, or ___________.
faults
• In response to this stress, rock in the plates
_______________.
deforms
Elastic _______________
deformation leads to earthquakes.
• __________
• It’s like a stretched rubber band, you can only
stretch rock so far before it breaks. When the
energy
rock breaks, it releases ________________.
• This energy is released in the form of seismic
waves.
Volcanoes
• Tectonic plate boundaries are likely places
for _____________
volcanoes to form.
• ________
_____
which are
The _________
Ring
of _________,
Fire
plate boundaries surrounding the Pacific
Ocean, contains nearly 75%
_____ of the world’s
active volcanoes.
• About _____
80% of active volcanoes on land
form where plates ______________,
and about
collide
15% form where plates ____________.
separate
______
• At these plate boundaries it is possible for
_____________
to form and travel to the
magma
surface. Draw a picture of both types of volcano
formations. Use pages 464-465.
Let’s Review…
3-2-1 Reflection
• 3 things that I learned…
• 2 questions I have…
• 1 way I can relate today’s lesson
to my daily life…