Lesson 2: Historical Evidence (Wegener)

Key Idea

In the early 1900s, a German scientist named Alfred Wegener challenged the idea that continents were fixed. He noticed that the coastlines of South America and Africa looked like fitting puzzle pieces and proposed the theory of continental drift.

Wegener hypothesized that the continents were once joined in a single landmass and had drifted apart. Although he lacked a mechanism (he didn't know about plates yet), his radical idea laid the foundation for modern plate tectonics.

Key Idea

Wegener’s strongest proof came from fossils. He found identical fossils of the reptile Mesosaurus and the fern Glossopteris on continents separated by vast oceans.

Since these organisms could not swim or fly across an ocean, the only logical explanation was that the landmasses were connected when these creatures were alive. This fossil evidence provided the necessary support to argue that the continents had moved over time.