If you look at the shape of the Earth's continents, Africa and South America look like the pieces of a that could snap together. This supports the that all of the continents were once one big continent called . Scientists believe Pangea existed about 2 or 3 hundred years ago. Then Pangea started to break apart, eventually forming the we see today.
The surface or crust of the Earth is broken up into about 18 floating on the liquid . When the plates move, continents shift along with them. You hardly ever notice the ground moving; continents only move a few every year.