A WEBQUEST

Pangaea – The Supercontinent

Do You Think the World Has Always Looked Like This?

Can You Believe That the World Might Have Looked Like This a Long Time Ago?

The Theory of Pangaea

A theory is a well-researched idea or thought that has a substantial amount of evidence to support it. It isn’t a fact or law yet, and it can still be researched more and possibly proven wrong.

If you look at a modern day map of the world, it looks as though the edges of some of the continents could fit together like puzzle pieces. There is a theory that millions of years ago, our seven present-day continents formed one huge continent, named Pangaea.

Check out the following websites:

Pangaea - Whole Land (read whole page)

Pangaea (read top paragraph only)

The Pangaea Theory (read top paragraph

only)

The Theory of Continental Drift

German meteorologist and geophysicist Alfred Wegener (VEG nur) thought that the fit of the continents was not a coincidence. In 1912, he proposed the theory of Continental Drift.

Check out the following websites:

PBS - People and Discoveries - Albert Wegener(skip bottom paragraph)

Continental Drift (skip Tectonic Activity section)

Albert Wegener looked at a map and noticed that the coasts of Africa and South America looked like the edges of pieces of a jigsaw puzzle that fit together.

Albert Wegener, 1880-1930

Pangaea & Continental Drift Animations

The following websites show the supercontinent of Pangaea drifting apart into seven separate, present-day continents. View each one.

Animation of the Break-Up of Pangaea 1

Animation of the Break-Up of Pangaea 2

Animation of Continental Drift

Now You Try….

The following interactive website (game) will allow YOU to reconstruct Pangaea:

Move the Continents!

The following interactive website (game) will allow you to identify modern-day continents in Pangaea:

The Earth, 250 Million Years Ago...

Evidence for Continental Drift

1. Pieces of a Puzzle

Africa and South America seem to fit together.

Evidence for Continental Drift

2. Identical species of animal fossils of the same age have been found on different continents.

For example, fossils of the freshwater/land reptile Mesosaurus have been found in South America and Africa. This would not have been possible had the two continents always been separated by the seawater of the Atlantic Ocean.

Mesosaurus fossil in rock

Evidence for Continental Drift

3. Identical species of plant fossils of the same age have been found on different continents.

For example, fossils of the tropical fern (plant) Glossopteris have been found in Africa, Australia, India, South America, and Antarctica. This would only be possible if the continents were once connected and shared a similar warm climate.

Glossopteris fossil in rock

Evidence for Continental Drift

4. Rock Clues

The West Coast of Africa and the East Coast of South America have very similar rock formations and mineral deposits, suggesting that they once were joined together.

Also, parts of the Appalachian Mountains in the Eastern United States are similar to those found in Greenland and Western Europe.

Evidence for Continental Drift

5. Climate Clues

There is evidence that glaciers once covered parts of tropical continents, such as South America, Africa, India, and Australia. It is believed that this was possible because these continents were once connected and located near the Earth’s very cold south pole.

What Causes Continental Drift?

Seafloor Spreading

In the 1960’s, scientist Harry Hess proposed that hot, less dense material below the Earth’s crust rises toward the surface at mid-ocean ridges. It then flows sideways away from the ridge in both directions.

As the seafloor spreads apart, magma moves upward and flows from the cracks. It becomes solid as it cools and forms new seafloor. As new seafloor moves away from the mid-ocean ridge, it cools, contracts, becomes denser, and sinks, helping to form the ridge. This slowly pushes the continents farther apart, at about 5 cm per year.

Check out the following websites:

Seafloor Spreading

Seafloor Spreading Animation 1

Seafloor Spreading Animation 2

Harry Hess, 1906-1969

How Far Do You Think the Continents Might Continue to Drift?

If the continents are drifting apart at 5 cm every year, then we can expect the continents to drift further apart and then possibly back together again in the future.

Check out this website that shows Continental Drift over the next 250 million years:Copy and paste this URL into the address bar then run the quicktime movie.

http://earth.rice.edu/mtpe/geo/geosphere/topics/plate_tectonics/plate_future.mov