Continental Drift Theory and Evidence

Continental Drift Theory

• Alfred Wegener, a German meteorologist, proposed the theory of continental drift.
• He noticed continents seemed to fit together like puzzle pieces, particularly the eastern coast of South America and the western coast of Africa.
• This observation, though known for centuries, was considered by Wegener as a significant clue.
• Wegener's theory suggested continents were once connected and have since drifted apart.
• He named the supercontinent Pangaea, which existed approximately 250 million years ago.
• Pangaea is a Greek term meaning "entire earth" or "all earth."
• Wegener's model showed modern continents joined as Pangaea.

Evidence for Continental Drift

• Apparent Fit of Continents: Continents seemingly fit together like puzzle pieces, suggesting a prior connection.
• Fossil Correlation: Identical fossils of the freshwater reptile Mesosaurus have been found in both South America and Africa. Other fossils exhibit similar patterns, aligning with continents once being together.
• Rock/Mountain Correlation: Similar rock types and mountain ranges in the northeastern US and Northern Europe. The evidence suggests these were linked and separated when continents drifted apart.
• Paleo-Climate Data: Glacial striations, evidence of ancient glaciers, have been found in tropical regions of South America and Africa, implying a shift in their positions and past climates that were once in polar areas. Bituminous coal (formed from compressed tropical plants) is found in locations that are now in cold environments, further supporting the idea of continental relocation.

Wegener's Contributions & Fate

• Wegener presented his theory in a book The Origin of Continents and Oceans.
• He proposed that Pangaea fragmented and the continents moved to their current locations.
• Despite his evidence, Wegener's theory was initially met with skepticism, lacking a mechanism for continental movement.
• Wegener died before his work was widely accepted. His expedition to the North Pole resulted in his death from exposure.