The hypothesis according to which continents are believed to have drifted along the Earth’s crust and collided with one another, resulting in the creation of mountain ranges, volcanoes and earthquakes, was not taken seriously for a long time because there was supposedly insufficient proof to support it. Despite the fact that the theory of plate tectonics is today considered to be one of the most important scientific revelations in the field of geology as it has enabled us to explain many phenomena that had before been thought of as inexplicable, its author was, at least during his life, believed to be more a madman than a scientist whose name would once become synonymous with the greatest paradigmatic leap in the history of earth sciences.
Arctic enthusiast responsible for the geological revolution
Alfred Lothar Wegener earned a PhD in astronomy from the University of Berlin in 1904, but had always been more fascinated with the Earth than with the sky and the stars. He was especially interested in geophysics and in the quickly developing fields of meteorology and climatology. Even though today he is not particularly well-known for his achievements in meteorology, he had contributed many original ideas and methods to this subject, and wrote a textbook which has in the German-speaking area long been recognized as the fundamental work in the field. He had always been fascinated with Greenland which he visited regularly on arduous and extensive scientific expeditions. There, he used weather balloons to follow the movement of air masses in the North.
One of the reasons Wegener was in love with Greenland was because he hoped it to be the very place where he would find evidence to confirm his unusual hypothesis that continents were, slowly, constantly moving. In a letter to his future wife in 1910, he wrote: “Is it not true that the eastern shore of South America and the western shore of Africa make a perfect match, as if the two were once one? I must examine this idea more closely.” Since then he constantly searched for arguments that could best support his unusual hypothesis.
In the autumn of 1911, when he was rummaging through the library of the University of Marburg, he stumbled upon a scientific article on identical fossils that geologists had found in separate corners of the world now divided by vast oceans. Traditionally, the correspondence between these findings was argued to be the consequence of the existence of land bridges which once enabled animals to cross the seas, but were later destroyed. However, Wegener had his own explanation of the matching fossils: the fossils were identical because the separate continents of our time were once close together.
The way the continents matched in their shape as well as the similarity between the fossils discovered convinced Wegener that they had once constituted a whole that became divided into parts which now moved in all directions. Europe is moving away from America, just as other continents are moving from each another. Another evidence supporting the hypothesis of the existence of a united “primordial continent”, which Wegener later named Pangaea, were mountain ranges which also matched and, if put together, would form a continuation from one continent to the other. Mining sites were another perfect fit and provided an additional argument in support of his theory.
Wegener described his idea about continents drifting across the surface of the Earth in his book The Origins of Continents and Oceans which was published in 1915. He later updated the book with new information, so three new editions were published before his death. Unfortunately, the experts of the time had difficulties accepting the idea of moving continents. The main problem was that Wegener was not able to explain the mechanism according to which the continents could move, and to reveal the forces causing the phenomenon.
He often referred to the analogy of a journey of an icebreaker through a frozen sea, and attributed the forces to the rotation of the Earth, but he failed to convince the experts. One geologist even calculated that a centrifugal force large enough to move continents would cause the Earth to stop rotating in less than one year. Another difficulty was that Wegener had false data to begin with, so he obtained some unusual results, like one which implied that Europe and North America were moving apart at 250 centimeters per year which was 100 times faster than exact measurements showed many years later.
Death in Greenland
During the First World War, Wegener was enlisted as a soldier at the front where he received two minor wounds because of which he was later transferred to the army’s weather service. After the war, he returned to his post at the University of Marburg, but soon found himself displeased with the possibilities of his academic advancement, so he accepted the position of the professor of meteorology and geophysics at the University of Graz in 1924. In 1930, he left for another expedition to Greenland. An expedition from which he would, unfortunately, never return.
Despite the severe cold, he and his local friend set off to find a group of colleagues who camped somewhere in the middle of the Greenland icecap and were starting to run out of food. They managed to break through to the camp and renew their supplies. They decided to return to the base after a couple days of rest. Regrettably, after 1st November when they left the camp, they were never to be seen alive again. Wegener’s body was discovered by another expedition the following May. He was lying on reindeer skin, wrapped up in his sleeping bag. His piercing blue eyes were still wide-open and, as the expedition leader wrote down in his journal, his face seemed to be smiling.
He died only a day or two after his fiftieth birthday. The cause of his death was most probably a heart attack. His friend tried to reach the shore alone, but soon all trace of him disappeared. The expedition that found Wegener’s body put up a big cross to mark the spot, but the movement of the Greenland ice soon knocked it down and it was not to be found in fifty years. Along with the cross, the ice had also swallowed Wegener’s body.
Evidence supplied by military projects
During the Second World War and after, navies started using sonars to examine the depths of the oceans as seas became more strategically important. Before, scientist had almost no knowledge of the ocean floors. The structure of the bottom revealed by the sonars uncovered a whole new world. First, they were surprised to find out that approximately in the middle of the Atlantic Ocean there was a mighty mountain range that was later named the mid-oceanic ridge. This mountain range runs deep beneath the sea except in the north where it rises above the surface of the sea as a piece of land we call Iceland. It was soon discovered that similar mountain ranges ran under other oceans as well. It was also found out that these mountain ranges had an extremely high volcanic activity. The other important argument supporting the theory of moving continents was also a result of a military project. During the Cold War, the superpowers surveyed each other to discover potential nuclear testing. An atom bomb explosion shakes the earth with such magnitude that, using a seismograph, it can be detected as a minor earthquake. With this in mind, the Americans installed several hundred devices for measuring seismic waves and used computers to analyze the data in a military base somewhere in Colorado. After a detailed examination of the measurements obtained, they were able to determine where under the sea floors many of the earthquakes began, and at the same time discovered that seismic waves under the upper layer of the lithosphere spread slower than through solid rocks. Under the upper layer of the solid lithosphere, at depths between 100 and 200 kilometers beneath the surface, lies the plastic asthenosphere over which the solid plates carrying the continents move.
On the basis of the above mentioned and several other discoveries, the hypothesis of the drifting continents was revived and by the end of the sixties became generally accepted, although only after a couple essential improvements of Wegener’s original idea were made. Continents do not plough through the bottom of oceans like an icebreaker through a frozen sea, but form vast tectonic plates with the ocean floors. It is not only the continents that move, as Wegener falsely assumed; the ocean floor moves as well. Continents are like loads on different conveyor belts represented by individual tectonic plates. The Earth’s surface is formed of ten large plates which move and are pushed one over the other. When two “loads” moving on two separate plates collide, a mountain range rises. Similarly, the movement of continents can help explain other features of the Earth’s surface. Today, the theory of plate tectonics is believed to be one of the essential theories of modern science on the structure of our planet.
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