Continental Drift TheoryContinental Drift Theory

No need to take notesNo need to take notesI have taken them for youI have taken them for you

"Doesn't the east coast of South America fit exactly against the west coast of Africa, as if they had once been joined?" wrote Wegener to his future wife in December 1910. "This is an idea I'll have to pursue."

Alfred was trying to get his girlfriend’s father to like him. Her father was a well-known geologist!!

Alfred Wegener (Vegener)Alfred Wegener (Vegener)• As a young scientist, As a young scientist,

Wegener was curious Wegener was curious about Earth’s continents.about Earth’s continents.

• In 1910, Mr. Wegener In 1910, Mr. Wegener formed a hypothesis formed a hypothesis which stated all the which stated all the continents were once continents were once joined together in a giant joined together in a giant landmass.landmass.

• He named this landmass He named this landmass PANGAEA.PANGAEA.

Wegener used 3 types of evidence Wegener used 3 types of evidence to prove his theory!to prove his theory!

1.Evidence from landforms1.Evidence from landforms 2.Evidence from fossils2.Evidence from fossils

3.Evidence from climate3.Evidence from climate

Evidence from landformsEvidence from landforms

• The shapes of the The shapes of the continents seemed to continents seemed to fit together.fit together.

• Mountain ranges and Mountain ranges and other features also other features also lined up.lined up.

The ‘jig-saw’ puzzle

EvidenceEvidence from landformsfrom landforms

The ‘jig-saw’ puzzle

Evidence from landformsEvidence from landforms

The ‘jig-saw’ puzzle

Evidence from landformsEvidence from landforms

Evidence from FossilsEvidence from Fossils

• Fossils from one Fossils from one continent matched continent matched fossils from other fossils from other continents.continents.

• Wegener used both Wegener used both plant and animal plant and animal fossils.fossils.

Glossopteris: a fern found on the southern continents

Mesosaurus: a freshwater swimming reptile found in Africa and South America

fossil matches

Evidence from Fossils

fossil matches

Evidence from Fossils

Evidence from ClimateEvidence from Climate

• Wegener looked at Wegener looked at certain areas on Earth certain areas on Earth and their climatesand their climates

• He noted that the He noted that the fossils he found on fossils he found on certain sections of certain sections of Earth did not match Earth did not match the current climate the current climate

• Glacier scratches in Glacier scratches in S. Africa S. Africa

Antarctic ice

Evidence from ClimateEvidence from Climate

Ice could not have extended this far. So...continents MUST have moved..

Evidence from ClimateEvidence from Climate

Drift awayDrift away

Continental Drift Theory

At first nobody believed Alfred Wegener’s theory…..

WHY YOU ASK!

He could not prove how or why the continents moved.

Scientists still do not appear to understand sufficiently that all earth sciences must contribute evidence toward unveiling the state of our planet in earlier times, and that the truth of the matter can only be reached by combing all this evidence. . . It is only by combing the information furnished by all the earth sciences that we can hope to determine 'truth' here, that is to say, to find the picture that sets out all the known facts in the best arrangement and that therefore has the highest degree of probability. Further, we have to be prepared always for the possibility that each new discovery, no matter what science furnishes it, may modify the conclusions we draw."

Alfred Wegener. The Origins of Continents and Oceans (4th edition)