1. Continental Drift

2. 4.1 Continental Drift
Drifting Continents
Continental drift is the idea that continents are moving very slowly, parallel to Earth’s surface.
Alfred Wegener proposed that the continents slowly drifted to their present-day locations over millions of years. 4

3. 4.1 Continental Drift
Pangaea
Approximately 255 million years ago, the continents were one big landmass named Pangaea. 3

4. Evidence for Continental Drift
Four major pieces of evidence:
Fit of Continents
Fossil Evidence
Rock types and mountain ranges
Climate evidence 2

5. 1. Fit of the Continents
Africa and South America fit together like a puzzle.

6. 4.1 Continental Drift
2. Fossil Evidence
Wegener used fossil evidence from a fossil of a fern called Glossopteris.

7. 3. Rock Types and Mountain Ranges
4.1 Continental Drift
3. Rock Types and Mountain Ranges
Ancient rocks on the continents match up when you assemble the continents as Pangaea.
Some mountain ranges appear as if they were once connected.

8. 4. Climate Evidence Sedimentary rocks record clues about climate.
4.1 Continental Drift
4. Climate Evidence
Sedimentary rocks record clues about climate.
The ancient climate of certain locations was very different from the present-day climate.
Tropical plants in Greenland, glaciers in Africa

9. 4.1 Continental Drift
Hypothesis Rejected
Wegener proposed that the same forces of gravity that produced tides moved the continents.
Scientists rejected this hypothesis because they did not accept Wegener’s explanation of how the continents moved.
New technology gathered additional evidence that supported the continental drift theory. (p.172) 1