The Continental Drift Theory
Looking at how massive the continents are, one may get the feeling that they have always been like this and will remain so for the rest of time. After all, how immovable the mountains do appear and how vast the rolling oceans seem. While the world’s terrain may come across as permanent (and indeed for most of human history people believed it to be so), the reality is that the Earth’s surface is in constant motion. Humans simply do not feel the movement of the Earth because it is too slow to be felt, except of course when earthquakes occur. This process takes hundreds of millions of years but over time dramatically changes the globe’s surface. One of the earlier models that explain this process is now known as the theory of continental drift. Despite being an early model that got some details wrong, the theory of continental drift established the foundations of the way society understands the Earth’s surface.
The history of the continental drift theory is relatively recent. Throughout history, people believed that the Earth’s surface has always been the same. People assumed that the continents have always been shaped the way they appear and have not changed since the dawn of time. This prevailing belief was radically challenged in 1912 when a man named Alfred Wegener published his theory that attempts to explain the movement of the continents. According to this theory, the world’s continents are in a perpetual state of motion. They are massive landmasses that drift across the world’s oceans. Wegener postulated that the globe’s surface once had only one supercontinent that he named “Pangaea” or “all earth”. Over time, this supercontinent broke up into pieces that drifted apart, eventually becoming the separate continents today. The theory also asserts that this process also influences the formation of geological structures. For example, the theory asserts that when two continents collide, they push against each other with such great force that the surface is pushed upwards to form mountain ranges. The theory was severely criticized when it was first published. People and even members of the scientific community simply cannot believe that the process the theory presents is possible. However, there is compelling evidence that support this theory.
Although Wegener’s theory of continental drift was met with skepticism and criticism when it was published, the body of evidence that supports his model was difficult to ignore. The first and perhaps most obvious clue pointing to this theory is the shape of the continents and how they seem to fit together like pieces of a jigsaw puzzle. For instance, the west coast of Africa is an almost perfect fit of the east coast of North America and South America. Furthermore, the east coast of Africa fits the west coast of Madagascar. In fact, Wegener’s observation of how the continents fit together is what inspired his theory. Wegener believed that while Pangaea broke into smaller pieces, many of the pieces retained some of their shape, thus accounting for why some of the continents’ edges reflect each other’s contours.
While the shape of the continents is the most obvious piece of evidence, it is not the strongest. More compelling evidence has been noted in the fossils from various continents. Wegener studied fossils collected from different parts of the world. He noticed that that many fossils were strikingly similar. An example of this is fossils of freshwater reptiles found in the south of Brazil and fossils found in South Africa. These fossils come from the same time period. Assuming that the continents do not move, these fossils should be different from each other considering that many of them are separated by oceans. The plants and animals of these fossils would have developed differently and became entirely different species with no similarities. On other hand, assuming that the continents were once joined but later broke up explains the fossils’ similarities. The fossils indicate that South America and Africa were once joined. In particular, the areas in the south of Brazil and South Africa where the similar fossils were found were once part of the region populated by the same animals.
Similar to fossils, rocks found in various parts of the world also show similarities. For example, rocks in Scotland bear the same features as rocks in the Appalachian Mountains in the United States. This indicates that these regions were once part of the same contiguous area. They just eventually got separated as the continents drifted apart.
The location of certain fossils also supported Wegener’s theory. During his studies of fossils, Wegener noticed that some fossils showed plants and animals that could have not thrived in the climate of the places in which they were found. For example, plants that were found in Norway were not adapted to life in frigid temperatures. The fact that they were found in this place indicates that the area moved to the north of the globe long after the plants died.
Despite compelling evidence that supported Wegener’s theory of continental drift, there were still many unanswered questions. For instance, Wegener did not have a concrete explanation as to how the continents moved. Neither was he able to demonstrate that the continents do in fact move. Breakthroughs in the middle of the 20 th century, however, gave credence to many points raised by Wegener’s theory. A new theory emerged known as the plate tectonics theory. Building upon Wegener’s model, this theory asserts that the crust is not a single landmass that covers the entire globe. Instead, the crust is made up of several landmasses known as “plates.” These plates shift around, sliding and crashing against each other. There are several pieces of evidence supporting the existence of these plates. For example, prominent geologic formations such as mountain ranges, fault lines, volcanoes, and trenches are located in the same places where scientists have identified the plates’ boundaries. An example to this is the Pacific Plate—a large landmass that lies beneath the Pacific Ocean. The edges of this plate constitute the Pacific Ring of Fire, an area characterized by increased volcanic and earthquake activity resulting from the plate clashing with other plates. Of course, developing the plate tectonics theory would have not been possible if not for Wegener’s pioneering ideas on the nature of the Earth’s crust.
When Alfred Wegener first published his theory of continental drift, he was met with skepticism. It was simply too far-fetched to think that something as large as a continent could move. But as evidence based on the continents’ shapes, fossils, and rocks show, the continents do move. Furthermore, more recent findings helped develop a more comprehensive theory. In many ways, the continental drift theory is no longer the most accurate, surpassed as it is by the plate tectonics theory. But it cannot be denied that Wegener’s theory established the science behind society’s current understanding of the world’s crust. By being bold enough to reimagine the workings of the Earth’s surface in a completely different way, Wegener’s theory dared future scientists to find clues that expand people’s knowledge of the world.