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Plate Tectonics: A Dynamic Earth

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For centuries, people believed the Earth's crust was static and immovable. However, the theory of plate tectonics, developed in the mid-20th century, revolutionized our understanding of the planet. It proposes that the Earth's outer shell, the lithosphere, is divided into several large, rigid plates that glide over the semi-fluid asthenosphere beneath them.

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The interactions between these plates occur at their boundaries, which are classified into three main types. At divergent boundaries, plates pull apart from each other, allowing magma to rise and create new crust; this process forms mid-ocean ridges. At convergent boundaries, plates collide, often causing one plate to slide beneath the other in a process called subduction, which leads to the formation of volcanoes and mountain ranges. Finally, at transform boundaries, plates slide horizontally past one another, frequently triggering earthquakes.

[Image of plate tectonic boundaries]

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Evidence supporting this theory is robust. The most famous early proponent, Alfred Wegener, noted that the coastlines of South America and Africa fit together like puzzle pieces. Furthermore, fossils of the same ancient species have been found on continents that are now separated by vast oceans, suggesting that these landmasses were once joined in a supercontinent known as Pangaea.