Drifting Continents

http://www.youtube.com/watch?v=TzzGPfVx32M

A. The Theory of Continental Drift1. Alfred Wagener2. All the continents were once

joined together in a single landmass and have since drifted apart

3. Super continent was named Pangaea

4. Continental Drift – Pangaea broke apart and slowly moved toward their present day location

I. The Theory of Continental Drift

Wegener1880-1930

earthobservatory.nasa.gov

Alfred Wegener first proposed the theory of

continental drift.

Did You Know?Wegener’s theory was rejected by

scientists because he could not

explain what force pushes or pulls

continents.

B. Evidence to support the theory

1. Evidence of Landforms – Mountain ranges in South

Africa line up with mountain ranges in

Argentina

Fit of Continents Across the

Atlantic

Mountain ranges in South America line up exactly with those in

Africa!

2. Evidence from Fossils – fossils are any trace of an ancient organism that has been preserved in rock (Example – Glossopteris which is a fernlike plant that lived over 250 million years ago and was found in Africa, South America, Australia, India, and Antarctica)

Notice how fossils lined up across continents!

http://evolution.berkeley.edu/evolibrary/images/history/fossils3.gif

3. Evidence from Climate – Tropical plant fossils found in polar climate and deep scratches in rocks that where formed from glaciers in tropical areas

Did you know... 1. that India was once in the Southern Hemisphere connected to Antarctica? 2. that North America was once surrounded by warm, tropical seas? 3. that Africa was once covered by glaciers, which were kilometers in thickness? 4. that the Sahara desert was once a tropical rain forest?

As North America has drifted to different latitudes, changing climates were

experienced. This shows the changes in the state of New Mexico.

Proof for Changing Climate

At one time, the area that

is New Mexico

(and the rest of

the USA was

below the equator!

• He could not find the force that was causing the continents to drift.

• Because of this, he could not convince anyone that continents could move.

• He died in Greenland on an expedition.

• At the time of his death, no one believed his hypothesis!

Technology developed during the 1940’s changed all that!

Alfred WegenerPangaea

GlossopterisSea floor Spreading

Magnetic pole reversalsProof: Climate, Fossils, Geological

Features

Tier 1 Must have