Our planet's surface is not one solid piece. It’s a cracked shell, broken into about 15 to 20 massive plates of rock. This is the theory of plate tectonics, and it explains nearly all of our world's volcanic and seismic activity. These plates float on a hot, semi-liquid layer deep within the Earth, constantly moving at a speed between 2 and 15 centimeters per year, which is about the rate human fingernails grow. The name comes from the Greek word 'tekton,' meaning builder. The slow, relentless interactions between these plates are what build the mountains, volcanoes, and ocean basins of our planet. For decades, however, the idea that solid continents could drift across the globe was dismissed as impossible. The biggest question was: what force could possibly move them?
Plate Tectonics
The unifying theory of geology explaining how Earth's outer shell is broken into pieces that move at the same rate human fingernails grow.
The Building Blocks of Our World
Frequently Asked Questions
What is plate tectonics?
Plate tectonics is the scientific theory that Earth's outer shell is divided into large, rigid plates. These plates float on a semi-liquid layer of the mantle and are in constant motion, driven by heat from the Earth's core. Their interactions are responsible for most earthquakes, volcanoes, and the creation of mountains.
Who first proposed that continents move?
In 1912, a German meteorologist named Alfred Wegener proposed the theory of 'continental drift'. He suggested the continents were once a single supercontinent called Pangea, citing how coastlines fit together like puzzle pieces. However, his theory was rejected because he could not explain how the continents moved.
How fast do tectonic plates move?
Tectonic plates move very slowly, at speeds between 2 and 15 centimeters per year. This is roughly the same rate that human fingernails grow. While this seems incredibly slow, over millions of years it is enough to move continents thousands of kilometers.
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