In 1912 a man named Alfred Wagner discovered that millions of years ago there was only one gigantic continent that he named it Pangaea. He also discovered that millions of years ago there was only one giant ocean he named panthalassa. But when he tried to tell people they did not believe him. His theory was based on another theory called plate tectonics. according to plate tectonics the earths crust is split into seven to twelve big plates and a few small ones. The plates move by spreading apart, sliding, or colliding. They move 2-15 centimeters a year. When the plates move continents slowly drift.
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