9­16 Evidence of Continental Drift.notebook
Scien
September 22, 2011
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What happened to India as
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the continents moved over
time?
India drifted
north and collided
into Asia.
Think back to
yesterday with your
flip books and the
movie clips we
watched!
Please get out your
flipbooks and yellow
sheets that were for
homework!
Questions from Flip Book
1. First appearance of land masses
North America
Australia
India
Antarctica
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
2. Which frame did you locate the final breakup of
Pangea? Why did you choose that frame and not
another? F6- because Pangaea had broken into 3 large
land masses
3. Using a world map, identify two
locations where mountain ranges exist and
where you hypothesize plate collision
between continents or parts of continents
have occurred.
4. If mountain ranges can form where plates are
colliding, what would you hypothesize might occur
where plates are separating?
Evidence of Continental Drift
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
• Map-makers in the 1400s
wondered why the coasts of
several continents matched
so neatly.
• They noticed that the
coasts of Africa and South
America look as if they
could fit together like
jigsaw puzzle pieces.
In the 1700s, geologists
thought that the continents
had always remained in place.
But in the early 1900s, one
scientist began to think that
the continents could have
once been joined in a single
landmass.
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
Alfred Wegener's
hypothesis was that all
the continents were once
joined together in a
single landmass and have
since drifted apart.
continental drift-the
hypothesis that the
continents slowly
move across Earth's
surface.
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
According to Wegener, the
continents drifted together to
form supercontinent Pangaea
which means "all lands"
Pangaea existed about 300
million years ago when reptiles
and winged insects first
appeared.
Great tropical forests, which
later formed coal deposits,
covered a large part of Earth's
surface.
How did Wegener
support his hypothesis
for continental drift?
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
He gathered his information
from different scientific
fields to support his ideas
about continental drift.
He studied land features,
fossils, and evidence of
climate change.
He published a
book, "The Origin
of Continents and
Oceans", in 1915.
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
Evidence from Land Features
When he pieced
together maps of
Africa and South
America, he
noticed that
mountain ranges on
both continents
line up.
He also noticed that coal
fields in Europe matched
up with similar ones in
North America.
In the 1960's, it was
recognized that the fit of the
continents could be even
further improved by fitting
the continents at the edge
of the continental slope —
the actual extent of the
continental crust.
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
Evidence from Fossils
An example is Glossopteris,
a fernlike plant that lived
250 million years ago.
These fossils have been
found in rocks in Africa,
South America, Australia,
India, and Antarctica.
Other fossil examples include the
fresh water reptiles Mesosaurus
and Lystrosaurus.
These fossils were found in areas
that are now separated by oceans
and neither could have swum great
distances across salt water.
Wegener inferred that these
reptiles had to have lived on one
large land mass.
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
Evidence from Climate
As a continent moves closer to
the equator it becomes hotter
and as it moves away, colder.
But continents carry with them
the fossils and rocks formed at
the previous locations.
Deep scratches in rocks
showed that continental
glaciers once covered South
Africa.
Continental glaciers are thick
layers of ice that cover
hundreds of thousands of
square kilometers.
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9­16 Evidence of Continental Drift.notebook
September 22, 2011
The climate of South
Africa is too mild today
for continental glaciers
to form.
Wegener concluded that
when Pangaea existed,
South Africa was much
closer to the South Pole.
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