The Continental Drift Theory
Have you ever looked at the map and wondered why the east coast of South America and the west coast of Africa seem to fit together like two pieces of a jigsaw puzzle? If you thought of this, then you are not alone. A scientist named Alfred Wegener also noticed this oddity and this prompted him to develop the continental drift theory . This theory postulates that the world’s continents are shifting in position—that is, they are “drifting” across the Earth’s surface. When Wegener first published his theory in 1912, it was met with both scepticism and criticism. After all, the idea is radical; the mountains look as if they can never be moved just as the seas seem unchanging, so how can the continents move? Modern society, however, sees this theory in an entirely different light. While Wegener’s continental drift theory was initially rejected, the theory has been widely accepted today due to the emergence of strong evidence, most important of which is the development of plate tectonics theory.
Though Wegener’s theory was rejected when it was first published, it was not without evidence. The first crucial piece of evidence that lends the theory credence is the geometric fit between the continents. In particular, the east coast of North America and South America fit with the west coast of Africa. Meanwhile, the west coast of India and Madagascar fit with the east coast of Africa. The fact that the continents’ edges seem to complement each other suggests that the continents were once linked with each other. Wegener theorized that the continents were once a single landmass that he called “Pangaea” which means “all of Earth. The second piece of evidence was the similar fossils found across various continents. Scientists noted that many fossils of prehistoric plants and animals from various parts of the globe are similar. For instance, fossils of a freshwater reptile found in Brazil are similar to fossils found in South Africa. If the continents have always been separate, the chances of finding similar fossils across different continents is improbable; fossils would have been unique to their continents. Assuming that the continents were once joined, on the other hand, explains the finding of the similar fossils. Finally, certain rocks were also similar in the different continents. For instance, rocks in the Appalachian Mountains in the east coast of the United States match rocks in Scotland. Hence, the similarity between rocks serves as evidence in the same way that the similarity between fossils does. But despite these evidence, Wegener was at a loss for an explanation of how the continents were drifting in the first place, and it was this missing piece of evidence that contributed to the rejection of his theory by the scientific community.
The real breakthrough that brought widespread acceptance of Wegener’s theory came in the development of the plate tectonics theory. During the 1950s to the 1970s, scientists around the world began to realize that the Earth’s crust is not a single landmass enveloping the world; rather, it is composed of several landmasses called “plates”. Several pieces of evidence point to the existence of these plates. For instance, the locations of geologic formations such as ridges, faults, trenches, volcanoes, and valleys correspond with plates’ boundaries. An example to this is the Ring of Fire, a region characterized by increased earthquake and volcanic activity, which roughly corresponds to the edges of the Pacific Plate. For reasons yet to be fully understood, scientists discovered that these plates do move. In fact, estimates show that these plates move at rate of a few inches each year. They collide to, slide against, and pull away from each other, thus causing geologic formations and events such as volcanic eruptions and earthquakes. With the movement of plates established, it provided the most important evidence that the continents do drift. In fact, the plate tectonics theory is often considered today as the updated version of Wegener’s theory.
As much as the Earth’s surface looks fixed, the reality is that it is ever changing. The continental drift theory, postulated by Alfred Wegener in 1912, is the first modern theory to describe the movement of the continents. Though the theory was accompanied by evidence such as the similarities between fossils and rocks from different continents which suggest that these continents were once joined together, the theory was rejected. However, the development of the plate tectonics theory that resulted from more recent discoveries provided the most crucial piece of evidence to Wegener’s theory, thus leading to the widespread acceptable of his theory. Indeed, Wegener’s theory is considered as predecessor to the plate tectonics theory. Much needs to be learned about the workings of the Earth. But the continental drift theory certainly provides excellent insight into the origins of the Earth.
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