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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