Why are there continents?

The continents are formed by lighter but thicker sections of the Earth's crust, which ride above the mantle and the thinner oceanic crust. The tectonic plates that form the continents are mostly in constant motion, sliding past, into, or away from each other. They all sit atop vast liquid oceans of magma (melted rock) heated by the mantle.

The current position of the continents, with the vast majority in the Northern Hemisphere, has only existed for less than 100 million years, after the last supercontinent, Pangaea, rifted apart. Fossils on the various continents indicate that they were all joined together when those plants and animals were alive.