Continental Drift

Alfred Wegener In 1910, Alfred Wegener became curious about the continents. He formed a hypothesis that the continents had moved.

Wegener’s hypothesis was that all continents had been joined together in a single landmass and have since moved apart.

He named this super continent Pangaea. This idea was known as Continental Drift.

Evidence 1. Landforms –Mountain ranges and other features on continents provided evidence. South America and Africa fit together like puzzle pieces. A mountain range in South America lined up with a mountain range in Africa. European coal fields matched up with ones in North America.

2. Fossils –A fossil is a trace of an organism preserved in rock. Fossils of the reptiles Mesosaurus and Lystrosaurus had been found in places now separated by oceans. Another example was the fern- like plant Glossopteris found in Antarctica, Africa, South America, Australia and India.

Laurasia -included most of the landmasses that make up today’s northern hemisphere. Gondwanaland - Southernmost supercontinent that was once part of Pangaea

3. Climate –Fossils of tropical plants were found in Antarctica. –Glaciers once covered South Africa. Deep scratches from the glaciers were found on rocks.

Rejection of Wegener’s Hypothesis Wegener could not provide evidence for the forces that push or pull the continents. Many geologists in the 1900’s thought the earth was slowly shrinking and cooling. Wegener disagreed with this proposal because mountains usually appear in narrow bands along the edge of continents

New evidence today: The Ring of Fire; showing that the plates once were connected and seismic activity in the mantle has caused the movement and the eruption of volcanoes and earthquakes.