Continental Drift to Plate...
Transcript of Continental Drift to Plate...
Continental Drift &
Plate Tectonics
Is this SERIOUSLY happening????
If you take a look at a globe, you can see
that if we were to squish the land all
together, most of the continents seem to
fit together like a puzzle.
For example, the west African coastline
seems to snuggle nicely into the east
coast of South America and the Caribbean
sea.
http://www.uwsp.edu/geo/faculty/ozsvath/images/continental%20fit.jpg
In 1915 Alfred Wegener
proposed:
• all the continents were once
all one in a single massive
continent called Pangaea
(meaning "all lands")
•over time they drifted apart to
their current spots
•Pangaea was intact until
about 300 million years ago,
then began to break up
http://www.awi-bremerhaven.de/AWI/Presse/PM/pm05-
1.hj/pics/Wegener-w.jpg
Wegener was a German
meteorologist who also was
an explorer in Greenland.
He died there in his tent
while travelling to relieve a
group of scientists who
were without enough food.
http://www.ocean.washington.edu/education/magic/images/pangea1.gif
Pangaea: approximately 300 million years ago
Wegener had four
main pieces of
evidence (or
reasons why he
believed his theory
was true):
1. The jigsaw fit of
the continents,
especially South
America and Africa Making Connections: Canada’s Geography. Clark & Wallace.
Prentice Hall Ginn, 1999.
2. If we go far enough
back in our fossil
records, we find
fossils that are the
same on both sides
of the Atlantic
Eventually, the fossils
start to differ from
each other,
suggesting they were
geographically
separated. Making Connections: Canada’s Geography.
Clark & Wallace. Prentice Hall Ginn, 1999.
3. Geologic evidence: mountains have the
same age and structure on both sides of
Atlantic
Making Connections: Canada’s Geography. Clark & Wallace. Prentice Hall Ginn, 1999.
4. Ice sheets
covered parts
of Africa, India,
Australia and
South America
250 million
years ago.
How could this
happen in
places that are
so warm
today?
Making Connections: Canada’s Geography. Clark & Wallace. Pearson, 1999.
India? Glaciated??!! Huh?!
Click on this link to see a great animation
of the spreading of the Atlantic Ocean.
http://earthref.org/cgi-bin/z-
download.cgi?database_name=erda&searc
h_start=advanced&h=html-
header&file_path=/projects/earthref/archive
/archive/aaab/m00002.i1.2.seafloor.spreadi
ng.swf
He knew they moved,
but could never prove
HOW they moved!
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So, Wegener's idea of continental drift made
SENSE but was missing an explanation of how the
continents could drift across the earth's surface.
Things That Make You Go..hmmm
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It wasn’t until the 1960s that
the theory of plate tectonics was
advanced to explain how the
continents could separate.
A Canadian by the name of
J. Tuzo Wilson played an
important part in the
development of this theory.
http://www.psych.utoronto.ca/~rci/graphics/Tuzo_
Wilson.jpg
Companion of
the Order of
Canada.
First Director
General of the
Ontario Science
Centre.
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It was Wilson who
came up with the
Theory of Plate
Tectonics that the
plates are floating on
the mantle (magma)
and different
convection currents
moves the plates
around (think boiling
water moving the lid...) 14
Remember THIS diagram??
Convection currents power the plate
movements. They rise up from the
radioactive core, carrying heat to the thin
crust of the earth.
http://geog.ouc.bc.ca/physgeog/contents/10i.html
Continental
crust
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Plate Tectonics
http://geothermal.marin.org/GEOpresentation/images/img007.jpg
Crust is
created Crust is
“destroyed”
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