Unit 3: Plate Tectonics

AIM: What evidence did Wegener

have forContinental Drift?

What is Continental Drift?• Continental Drift: all of the

continents were once joined together in a single landmass, and have since drifted apart.

• This hypothesis was created by a young German scientist, Alfred Wegener, in 1910.

What is Continental Drift?• According to Wegener, the continents drifted

together to form the supercontinent, Pangaea.–Pangaea existed about 300 million years ago.

Evidence of Continental Drift1. Fit of the continents: coastlines fit together like

puzzle pieces.

Evidence of Continental Drift2. Plant and Animal Fossils: certain fossils can be found in places now separated by oceans.

The reptile Mesosaurus swam in the freshwaters of Pangaea 260 million years ago. Today, its fossils are

only found in Africa and South America.

Evidence of Continental Drift3. Land features: mountain ranges on different continents line up when placed together.

Evidence of Continental Drift4. Climate: Tropical plant and animal fossils are found near the poles, and evidence of glaciers is found in warm regions.

Why was Wegener’s hypothesis rejected?

• Wegener could not provide a good explanation for WHY the continents would move.