DRIFTING CONTINENTS

DRIFTING CONTINENTS

Do you see the pieces of the jigsaw-puzzle?

DRIFTING CONTINENTS

DRIFTING CONTINENTS

Theory of Continental Drift – Alfred Wegener’s theory that all continents

were once one landmass called Pangaea (theory proposed in 1910)

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DRIFTING CONTINENTS

200-300 million years before present – Pangea existed, and later, over tens of millions of years, Pangaea breaks up to form present landmasses

Continental Drift

What is the EVIDENCE? (proof)

What evidence is there that Pangaea even existed?

There are 3 pieces of evidence: 1. Landforms 2. Fossils 3. Climate

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Evidence from Landforms – Mountain belts that match up in South Africa, Argentina, and South America; Coalfields in North America and Europe match up

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Glacial striations on rocks show that glaciers moved from Africa toward the Atlantic Ocean and from the Atlantic Ocean onto South America. Such glaciation is most likely if the Atlantic Ocean were missing and the continents joined.

DRIFTING CONTINENTS

DRIFTING CONTINENTS

DRIFTING CONTINENTS

Evidence from Fossils – Glossopteris plant fossils found in Africa, South America, Australia, India, & Antarctica; these seeds are not designed to travel a great distance or survive ocean travel

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Glossopteris fossil found in Antarctica.

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DRIFTING CONTINENTS

Evidence From Climate – Island in Artic Ocean called Spitsbergen has

fossils of tropical plants

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The island of Spitsbergen

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Rejection of Wegener’s Theory – Wegener’s theory was rejected by most scientists because he could not identify the mechanism for HOW continents drift

DRIFTING CONTINENTS

DRIFTING CONTINENTS

Question

How would you explain how the continents might have moved? Why does heat transfer have something to do with it?