What is Continental Drift?

What is Continental Drift?

What is Continental Drift?

In 1912, Alfred Wegener published a theory to explain why the Earth looked like a huge jigsaw. He believed the continents were once joined, forming a supercontinent he called Pangaea. Over 180 million years ago, this supercontinent began to “break up” due to continental drift.

Continental drift

Continental drift

During the 20th Century, scientists developed the theory of Plate Tectonics. The theory suggests that the crust of the Earth is split up into seven large plates (see map below) and a few smaller ones, all of which can slowly move around on the Earth’s surface. They lie on the ductile mantle that allows them to move. There are several explanations for the movement of the Earth’s plates, and these are explored in the Why do plates move? page.

The Earth's main tectonic plates

The Earth’s main tectonic plates

What is the evidence for continental drift?

Wegener’s evidence for continental drift was that:

  • the same types of fossilised plants and animals are found in South America and Africa;
  • the east coast of South America fits the west coast of Africa like a jigsaw puzzle;
  • rock formations and mountain chains match in South America and Africa;
  • similar mineral deposits and natural resources, such as coal, exist along the east coast of Africa and the west coast of South America.

Summary

  • Wegener’s Theory

    In 1912, Alfred Wegener proposed that the continents were once joined as a supercontinent called Pangaea and have since drifted apart.

  • Supercontinent Pangaea

    Pangaea existed over 180 million years ago before breaking up due to continental drift.

  • Evidence for Continental Drift

    Wegener used fossil similarities, matching rock formations, and the jigsaw-like fit of South America and Africa as evidence.

  • Fossil and Rock Matches

    Identical fossils and mountain chains are found in both South America and Africa, supporting the theory.

  • Modern Understanding – Plate Tectonics

    Scientists later developed the theory of plate tectonics, explaining that Earth’s crust is divided into plates that move slowly over the mantle.

  • Movement of Plates

    Tectonic plates rest on the ductile mantle and move over time due to processes like slab pull and ridge push.

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