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The Theory of Plate Tectonics

The theory of plate tectonics is the unifying framework of modern geology, explaining how the Earth's surface features are formed and change over time. It posits that the planet's outer layer, the lithosphere, is broken into several large and small rigid plates that move over the semi-fluid asthenosphere beneath. This idea was built upon the earlier concept of continental drift, proposed by Alfred Wegener in the early 20th century. Wegener presented evidence that the continents were once joined together in a supercontinent he called Pangaea, but his theory was initially dismissed because he could not provide a plausible mechanism to explain how the continents moved.

The scientific community remained skeptical of Wegener's ideas for decades. However, after World War II, new evidence emerged from oceanographic research. Scientists mapping the ocean floor discovered mid-ocean ridges, deep-sea trenches, and a pattern of magnetic stripes on either side of the ridges. These discoveries led to the development of the seafloor spreading hypothesis, which suggested that new oceanic crust is formed at ridges and moves outward. This provided the long-sought-after mechanism for continental movement, and the theory of plate tectonics became widely accepted by the 1960s.

Today, the theory of plate tectonics explains a vast range of geological phenomena. The interactions at the boundaries where plates meet are responsible for creating earthquakes, volcanoes, and mountain ranges. At convergent boundaries, plates collide; at divergent boundaries, they pull apart; and at transform boundaries, they slide past each other. This elegant and powerful theory not only explains the past configuration of the continents but also allows scientists to understand the ongoing dynamic processes that continue to shape our planet.