continental drift plate tectonics...wegener had four main pieces of evidence for his theory on...
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Plate Tectonics Continental DriftNOTES
I can describe the theory of continental drift.
November 2, 2020
When I think of plate tectonics or continent drift, I
think of...
Let’s go back into history!
Continental Drift
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Did you know that someday in the future, coastal California and Baja California will separate from North America and drift out into the Pacific ocean?
Alfred Wegener● German scientist● Noticed in the early 1900’s that
some continents seemed to fit together as a puzzle
● Wegener hypothesized that these continents were once a great land mass or supercontinent called Pangea
Continental Drift
The Idea that the continents move around and change locations on Earth.
Alfred Wegener proposed the idea of Continental Drift
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What do you notice about the shapes of the continents?
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“Continental Drift” Evidence #1: Shape
“Continental Drift” Evidence: Fossils
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“Continental Drift” Evidence: Mountain Belts
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“Continental Drift” Evidence: Glacial Markings
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MovingContinents
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…Back in time…
Pangea
Supercontinent~250 Myr ago
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North America!
● The Continents Move Around on Earth● Evidence for Continental Drift:
Shape of the ContinentsFossils
Glacial MarkingsMountain Belts
● Pangea existed when all the continents were together
Conclusions
So, how come the scientific community disregarded Wagner’s hypothesis?
No explanation for the movement of the continents.
Theory of Plate Tectonics● Earth’s plates are in
constant, slow motion● Between 2.5 and 15 cm
per year!● Explains how plates
move and formSince you’ve been alive, plates have moved
more than 180 centimeters!!!
Theory of Plate Tectonics continued...
Geologists came to the conclusion in the 1960’s that the Earth’s lithosphere was broken up into about 12 large pieces called plates that are moving relative to one another.
The lithosphere floats upon the asthenosphere (upper mantle).
The crust and upper layer of the mantle together make up a zone of rigid, brittle rock called
the lithosphere.
Continental crust is less dense than oceanic crust.
Continental crust is composed of granite. Oceanic crust is composed of basalt.
Plate Movement● Plate motion is the result of
the movement of material in the upper mantle, which drags the overlying plates above.
● Convection currents take place in the mantle
Convection Currents● the transfer of heat by movements within a
fluid○ hot rises, cool sinks
● Convection currents within the mantle cause the plates to move
Continental DriftThe process continues as the current earth/volcano hot spots of the world reflect the edges of the moving plates atop which the continents sit.
Quiz Time!1. The plates move along the top of the
A. coreB. asthenosphereC. crustD. inner core
Quiz Time!2. Plate movement occurs because of
A. conduction currents in the mantleB. convection currents in the mantleC. convection currents in the crustD. conduction currents in the crust
Quiz Time!3. Earth’s lithosphere is broken into a number of large pieces called…A. faultsB. volcanoesC. platesD. folds
Today’s assignmenthttps://docs.google.com/presentation/d/1_IoH40FmnIuPvUo3k_1ZeHd882K3pnJc0ZjHGu9i3uM/copy?usp=sharing
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Use this website to answer the questions below.
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Type example here
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Wegener had four main pieces of evidence for his theory on Continental Drift. Use this website to give examples of each.