Doesn’t the east coast of South America fit exactly against the west coast of Africa, as if they had once been joined? This is an idea I’ll have to pursue.” – Alfred Wegener said to his future wife, in December 1910. We can’t really get into Alfred Wegener’s head, but we can imagine that he started his investigations by trying to answer this question: Why do the continents of Africa and South America appear to fit together so well? Is it a geometric coincidence that they do, or is there some geological reason?
Alfred Wegener, born in 1880, was a meteorologist and explorer. In 1911, Wegener found a scientific paper that listed identical plant and animal fossils on opposite sides of the Atlantic Ocean. Intrigued, he then searched for and found other cases of identical fossils on opposite sides of oceans.
The explanation put out by the scientists of the day was that land bridges had once stretched between these continents. Instead, Wegener pondered the way Africa and South America appeared to fit together like puzzle pieces. Other scientists had suggested that Africa and South America had once been joined, but Wegener was the idea’s greatest supporter.
Wegener obtained a tremendous amount of evidence to support his hypothesis that the continents had once been joined. Imagine that you’re Wegener’s colleague. What sort of evidence would you look for to see if the continents had actually been joined and had moved apart?