Scientists once believed Earth's continents were fixed in place and never moved. This changed when Alfred Wegener's continental drift theory proposed that continents slowly drift across Earth's surface over millions of years.
Wegener gathered several types of compelling evidence to support his revolutionary idea. He noticed that the coastlines of South America and Africa seemed to fit together like puzzle pieces. He also found matching rock formations and mountain chains that lined up when the continents were positioned together. Most importantly, he discovered similar fossil distribution across continents, including identical plant and animal fossils found on lands now separated by vast oceans. These fossils showed that organisms that couldn't have crossed oceans were somehow present on multiple continents. This led Wegener to propose that all continents were once joined in a supercontinent called Pangaea before breaking apart and drifting to their current positions.
Despite his strong evidence, Wegener faced fierce objections to his continental drift model from the scientific community. Critics argued that there was no known mechanism that could move such massive continents across the ocean floor. They also questioned how rigid continents could plow through the solid oceanic crust without breaking apart. The scientific establishment largely rejected Wegener's theory during his lifetime. However, later discoveries about seafloor spreading and plate tectonics in the 1960s finally provided the missing mechanism for continental movement. Modern scientists now recognize that Wegener was fundamentally correct about continental drift, even though he didn't fully understand how it worked. His careful observations and willingness to challenge accepted ideas eventually led to our modern understanding of how Earth's surface has changed dramatically over geological time.
