Download I-6 Dynamic Planet Notes

I-6 Dynamic Planet
Notes
Activity Notes and Digging
Deeper Notes
Evidence of a Super Continent
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Continents fit together. See the
match between the east coast of
South America and the west coast of
Africa.
Several of the world’s mountain
ranges that appear on a continent
today are similar in age and form to
mountain ranges that are on another
continent.
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Several fossils are found on particular
landmasses but not on others
Cynognathus was a reptile that lived in
what are now Brazil and Africa
Lystrosaurus was found in central Africa,
India, and Antarctica
Glossopteris was a fern found in
Antarctica, Australia, India, Southern
Africa, and South America
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Mesosaurus was found in the
southern tip of South America and
the southern tip of Africa
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Evidence produced by glaciers from
long ago provide geoscientists with
ideas about the movement of
continents.
Like a bulldozer, a glacier plows a
large pile of rock and sediment.
When the glacier melts, the “plowed”
deposit, called a terminal moraine, is
left at the front of the glacier
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Evidence of ice sheets 300 million
years old has been found in the
southern hemisphere
Super Continent
Digging Deeper Notes
Continental Drift
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Believed over 100 years ago based
on observation of how Africa and
South America fit together-Perhaps
was once a single continent
Idea is that the single continent
broke apart and the pieces drifted
away from each other to form the
Atlantic Ocean
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Theory not accepted by geoscientists
until the 1960’s
The Theory of Plate Tectonics gave a
natural explanation for continental
drift
Supercontinents
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Geoscientists are sure that about
250 million years ago all of the
Earth’s continents were gathered into
a single “supercontinent”
Formed by a series of continentcontinent collisions
Named Pangea (“Pan” means “all”,
and “gea” means “land”)
Suture Zones
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Evidence for the existence of Pangea
Former continent-continent collisions
Are found in the interiors of
continents
Believed to be where earlier
continents joined to form Pangea
Example, the Appalachian Mountains
in North America
The Breakup of Pangea
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About 200 million years ago the
pattern of convection cells in the
mantle changed
Caused Pangea to slowly split apart
Process is called continental rifting
Caused the Atlantic, Indian, and
Antarctic Oceans to grow larger
Rifts didn’t develop in the same
places where Pangea was first
sutured together
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There is evidence of earlier
supercontinents. One may have
existed about 600 million years ago.
At the time of Pangea, the Pacific
Ocean was the only ocean! (Pacific
Ocean is surrounded by subduction
zones and is being consumed
Prediction for the Future
Pacific ocean will continue to shrink
until all of today’s continents collect
to form a new supercontinent
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The pacific ocean will expand again,
and the new oceans will close up
again to form a Supercontinent
where Pangea once existed
(Scientists believe the latter)
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The measurement of plate
movement is made by using a
satellite-based global positioning
system (GPS)
I-6 AYR Questions
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In your own words, explain the
theory of continental drift.
What was Pangea?
How is a suture zone formed?
Why is the Pacific Ocean shrinking?
Answers to AYR
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1. According to plate tectonic theory,
the outermost layer of the Earth
consists of pieces of lithosphere
called plates. The plates move
relative to one another. Some of the
plates have continents on them. The
continents move relative to one
another.
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2. Pangea (Pangaea) was a continent
that existed about 250 million years
ago. It consisted of all of the Earth’s
continents, which had been gathered
by continental drift into a single large
continent, called a supercontinent.
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3. A suture zone is the place where
two separate continents come
together to form a single continent.
Suture zones form at continentcontinent collision zones.
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4. The Pacific Ocean is shrinking because
there are subduction zones all around it.
Oceanic lithosphere is being consumed at
those subduction zones. There are midocean ridges in the Pacific also, but the
rate of production of new oceanic
lithosphere there is less than the rate of
consumption of oceanic lithosphere at the
subduction zones, so Pacific is shrinking.