Drifting Continents:

The Continental Drift Theory

Continental Drift

• 1910: Alfred Wegner came up with the theory of continental drift

• Theory: Wegner hypothesized that all the continents were once joined together in a single landmass and have since drifted apart.

• Named the super continent Pangaea (meaning “all lands”)

Pangaea

• Existed about 300 million years ago

Evidence?

• Wegner was not taken seriously because he had no hard evidence.

• Gathered evidence to support his theory

– Land Features

– Fossils

– Climate Change

Land Evidence

• Africa and South America

– Mountain ranges on both continents matched up!

• Coal fields

– European coal fields match up with the coal fields in North America

Fossil Evidence

• Glossopteris

– Fernlike plant lived over 250 mya

– Fossils have been found in Africa, South America, Australia, India, and Antarctica

– Very spread out today with varying climates

• Mesosaurus and Lystorsaurus

– Fossils found in places now separated by oceans

– Neither reptile could swim these large distances

Climate Evidence

• Glacier Evidence- same deposits left in many different continents: South America, Africa, India, Australia, and Antarctica

• Fossils of tropical plants found on an island in the Arctic Ocean

• Coal: formed in warm swampy climates, but deposits have been found in Antarctica

• Salt Deposits: form in areas 10-30° N/S of the equator- but have been found as far north as Michigan