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The Theory of Plate Tectonics

The theory of plate tectonics is a cornerstone of modern geology, providing a comprehensive explanation for many of the Earth's most significant geological processes. The theory posits that the Earth's rigid outer layer, the lithosphere, is broken into a mosaic of large and small plates. These tectonic plates are not static; they are in constant, slow motion, gliding over the semi-fluid asthenosphere beneath them. This movement is driven by convection currents in the Earth's mantle, as hot material rises and cooler material sinks.

The interactions at the boundaries where these plates meet are responsible for much of the planet's seismic and volcanic activity. There are three main types of plate boundaries: divergent, where plates pull apart; convergent, where plates collide; and transform, where plates slide past each other. For example, earthquakes are common along transform boundaries like the San Andreas Fault, while many of the world's most prominent mountain ranges, such as the Himalayas, were formed by the collision of convergent plates.

The concept of plate tectonics unified several earlier geological observations and theories, most notably Alfred Wegener's early 20th-century theory of continental drift. Wegener had proposed that the continents were once joined together in a single supercontinent called Pangaea but lacked a convincing mechanism to explain their movement. It was not until the 1960s, with evidence from seafloor spreading, that the full theory of plate tectonics was developed and widely accepted, revolutionizing our understanding of the planet.