Before the 19th century, there was no explanation for the mysterious distribution of some of the plants and animals on the planet:

• Why is the fauna of North America and Europe similar on both sides of the Atlantic, while the fauna of South America and Africa so different?

• Why is the fauna of Australia so different from the fauna of the other continents?

• Why are there marsupials in America, like opossums?

• Why are there generally no large mammals on islands? Why are there camel fossils in America, but no modern-day camels exist?

Science should be able to clarify these questions with evidence. As Darwin suggested, “the current global distribution of plants and animals is the result of their dispersal from their place of origin.” Similar species must have evolved from common ancestors. Since the beginning of the 19th century, the existence of almost identical fossils in distant continents, like Africa and India, or South America and Africa, was well known. No one ever considered that the continents had drifted to their current locations. The idea defies common sense. But alas, while common sense is necessary, it’s not always reliable. 

Alfred Wegener, a German geophysicist from the early 20th century, was the first to suggest that continents are large masses that move relative to one another.

Wegener is known for his pioneering work in the concept of continental drift, the original term for plate tectonic theory. Wegener compiled in-depth empirical evidence that left no doubt that the Earth’s continents have changed position over time. His evidence includes: 

• Paleozoic rocks in southern Scotland and Ireland are more like rocks found in Canada’s Newfoundland than those found in northern England.

• The coal fields of Belgium and the British Isles are aligned with those of the Appalachian Mountains in North America.

• Kimberlite magma appears in both Africa and South America. Kimberlites are very rare volcanic eruptions that bring material from the depths of the Earth, where diamonds are formed.

• Fossils of the same plants and animals can be found in distant regions of the Earth, such as the Glossopteris plant in Australia, Antarctica, India, Africa, and South America, and the Mesosaurus reptile in South America and Africa.

• There is geological evidence that South America, India, Africa, and Australia experienced an ice age during the Carboniferous and Permian eras. At the same time, humid, warm forests covered North America, Europe, and Asia.

• The most obvious evidence for Wegener’s theory is the fact that the east coast of South America seems to fit perfectly with the west coast of Africa.

Ironically, geology, the science dedicated to studying Earth’s oldest rocks, is one of the most recent. The fundamental idea on which geology is based – that of plate tectonics – is more recent than the invention of the laser beam and the discovery of the genetic code.