The Earth’s crust (top layer) is not a solid shell. It is made up of thick, connecting pieces called tectonic plates. These fit together like a puzzle.

Underneath the plates is thick, soft, hot flowing rock called mantle. This is what makes tectonic plates move around like a puzzle and not be solid.

Scientists believe that 220 million years ago, today’s continents may have all been joined together as one supercontinent called Pangaea. They looked at maps and saw the continents looked like they fit together like a puzzle. They also found that there are similar rock types, deserts and fossils in the places where the continents look like they would join.