Transcript Plate Tectonics - 7thGradeScienceBCS

FINAL COMIC STRIP DUE
FRIDAY!!!!!!!!!
-Must submit all 3 drafts along with
peer/teacher feedback
WHAT IS THIS?
THIS IS NOT HOW EARTH LOOKS TODAY
Plate Tectonics
The theory of plate tectonics was first proposed by
Alfred Wegener in 1910. Wegener noticed that the
shorelines of the continents seemed to ‘fit together’
like the pieces of a giant jig saw puzzle.
Wegener’s theory stated:
1) The continents were once all
together in one
place forming a
supercontinent, Pangea.
2) The continents broke apart
and drifted to their
present locations.
Today plate tectonics and continental drift are accepted as facts.
Why? Let’s see the evidence!
L.T: I can explain why the Earths crust changes
The box represents a conveyor belt. The drawings represent
packages. Which person are the packages moving toward?
How do you know?
Packages are moving toward Joe, b/c the arrows on the top
where the packages are placed on are moving toward Joe.
Joe
Kara
Convection current:
Hot water rises because it’s lighter. When it reaches the top
then it cools and sinks because it gets heavier.
What Causes Plate Motion?
Convection currents within the Earth’s mantle
cause the plates floating on it to move. This
movement takes millions of years.
Similar to groceries on a conveyor
belt or a raft floating on a river.
Plates
Mantle
Next >
Introduction
Plates (tectonic plates): sections
of the Earths crust which are
constantly moving at a very slow
speed.
This movement causes
earthquakes, volcanoes, and the
continents and oceans to move
Plate tectonics: the movement of
the crust/lithosphere because of
movement in the mantle.
(convection currents)
Next >
The Earth’s crust is always moving!
Pangea
Pangea = Supercontinent (millions of years ago)
WHAT IS THIS?
THIS IS NOT HOW EARTH LOOKS TODAY
Plate Tectonics
The theory of plate tectonics was first proposed by
Alfred Wegener in 1910. Wegener noticed that the
shorelines of the continents seemed to ‘fit together’
like the pieces of a giant jig saw puzzle.
Wegener’s theory stated:
1) The continents were once all
together in one
place forming a
supercontinent, Pangea.
2) The continents broke apart
and drifted to their
present locations.

Continental Drift: The gradual movement
of the continents across the earth.
Copyright © 2010 Ryan P. Murphy
• The speed at which the plates move is about
the speed at which your fingernails grow.
Copyright © 2010 Ryan P. Murphy
• In 1915, The German geologist Alfred
Wegener (1880-1930) proposed continental
drift.
Copyright © 2010 Ryan P. Murphy
• In 1915, The German geologist Alfred
Wegener (1880-1930) proposed continental
drift. Not accepted until the 1950’s!
Copyright © 2010 Ryan P. Murphy
• In 1915, The German geologist Alfred
Wegener (1880-1930) proposed continental
drift. Not accepted until 1950’s!
“I say.” “Africa and South
America fit strangely like
two puzzle pieces.”
Copyright © 2010 Ryan P. Murphy

The shapes match.
Copyright © 2010 Ryan P. Murphy
FOSSILS!

The remains or impression of a prehistoric
organism (living thing: plant, animal,
footprint)

Same fossils found on different continents
Copyright © 2010 Ryan P. Murphy

The Same rock structures on different
continents
Copyright © 2010 Ryan P. Murphy
• What is this a fossil of?
– Where would you expect to find a specimen
like this on the planet?
Copyright © 2010 Ryan P. Murphy
• Answer! This is a fossilized tropical plant
found on Antarctica.
Copyright © 2010 Ryan P. Murphy
• Answer! This is a fossilized tropical plant
found on Antarctica.
– Remember, the continents have moved and
Antarctica use to be in a warmer climate.
Copyright © 2010 Ryan P. Murphy
• Answer! This is a fossilized tropical plant
found on Antarctica.
– Remember, the continents have moved and
Antarctica use to be in a warmer climate.
“Darn you
continental Drift.”
“Darn you.”
Copyright © 2010 Ryan P. Murphy

Fossils of plants and animals in Antarctica
Copyright © 2010 Ryan P. Murphy
CREATING PANGEA
• Today you will be recreating Pangea using
the fossil evidence.
• With your group cut out the tectonic plates
on your map and lay them on a piece of
construction paper.
• Use the fossil evidence to help you line up
the plates.
• Write your group members name on the
construction paper.
• Current Day + or – 4mm
• What causes continental drift and plate
tectonics?
Copyright © 2010 Ryan P. Murphy
• Answer!
– Convection currents (Remember heat rises)
move the plates
Copyright © 2010 Ryan P. Murphy
• Answer!
– Convection currents (Remember heat rises)
move the plates
Copyright © 2010 Ryan P. Murphy
• Answer!
– Convection currents (Remember heat rises)
move the plates
Copyright © 2010 Ryan P. Murphy
• Answer!
– Convection currents (Remember heat rises)
move the plates
Copyright © 2010 Ryan P. Murphy
• Which colored arrows are incorrect based
on the convection current patterns and
plate movements below?
Copyright © 2010 Ryan P. Murphy
• Answer! The blue arrows. The plates
should be moving toward each other.
Copyright © 2010 Ryan P. Murphy
• Answer! The blue arrows. The plates
should be moving toward each other.
Copyright © 2010 Ryan P. Murphy
“Oh-no!” “We
are trying it
again.”
• Try Again! Which colored arrows are
incorrect based on the convection current
patterns and plate movements below?
Copyright © 2010 Ryan P. Murphy
• Answer! The purple arrows should be
diverging instead of converging.
Copyright © 2010 Ryan P. Murphy
• Answer! The purple arrows should be
diverging instead of converging.
Copyright © 2010 Ryan P. Murphy
“Oh-no!” “We
are trying it one
more time.”
• Try Again! Which colored arrows are
incorrect based on the convection current
patterns and plate movements below?
Copyright © 2010 Ryan P. Murphy
• Answer! The light blue arrows should be
diverging instead of converging.
Copyright © 2010 Ryan P. Murphy
• Answer! The light blue arrows should be
diverging instead of converging.
Copyright © 2010 Ryan P. Murphy
“Oh-no!” “We
are trying it one
more time.”
• Try Again! Which colored arrows are the
only correct on in the entire group.
Copyright © 2010 Ryan P. Murphy
• Try Again! Which colored arrows are the
only correct on in the entire group.
Copyright © 2010 Ryan P. Murphy
Let's sum up everything we've learned:
1) The earth's crust is divided into many pieces called tectonic
plates which move around over long periods of time.
2) Evidence for crustal movement includes:
a) The 'fit' of the continents.
b) Correlation of rock types from opposite shores.
c) Correlation of fossils from opposite shores.
d) Age of the sea floor (youngest near mid-ocean ridges
and oldest near the continents).
e) Paleomagnetism: zones of oppositely magnetized
rock on opposite sides of the mid ocean ridge.
f) Direct satellite and GPS measurement of continental
movement.
3) The force driving the plates are convection currents (density
differences) in the earth's mantle.