Facts About Pangaea, Ancient Supercontinent
By Tia Ghose, Associate Editor | February 22, 2018 07:30pm ET
About 300 million years ago, Earth didn't have seven continents, but instead one massive supercontinent called Pangaea, which was surrounded by a single ocean called Panthalassa.
The explanation for Pangaea's formation ushered in the modern theory of plate tectonics, which posits that the Earth's outer shell is broken up into several plates that slide over Earth's rocky shell, the mantle.
https://www.livescience.com/38218-facts-about-pangaea.html