Millions of years ago, a person could walk through all the continents without any problems. There were no oceans that they needed to travel across to get from one landmass to another. This was because all of the earth’s continents were stuck together in one massive supercontinent called Pangea.

Gradually, however, what was once a single landmass, later detached and drifted into the 7 continents we have today. Now, it is impossible to walk from the Americas to Africa because of the large bodies of water that separate the continents.

Although it may seem like the land on Earth is fixed in place, in reality, it is constantly moving. This may come as a surprise to you since we can never feel the earth moving underneath our feet because the earth is moving in very small increments. In fact, it only moves about 1 to 6 inches per year. However, over millions of years, those inches added up to the thousands of miles that separate these now very distant continents.

The Earth has many layers, but the layer that is mainly responsible for this movement is the earth’s crust and upper mantle, also known as the lithosphere (li-thuh-sfeer). The lithosphere is broken into big chunks called tectonic plates. Think of a tectonic plate as an ice cube in soda. All the ice cubes floating on top of your soda make up the lithosphere, and each individual ice cube is a tectonic plate. Tectonic plates float on top of the asthenosphere (uhs-theh-nuh-sfeer), a layer of the earth made of liquid, rubbery melted rock, just like how an ice cube floats on top of soda. But how exactly are these tectonic plates able to move?

The Earth’s core is made of radioactive elements that generate immense amounts of heat. The hottest molten rock travels to the surface of the earth, where cools and sinks back to the core. This process of molten rock moving around the layers of the earth is called convection. The rising and sinking of molten rock pushes and pulls the plates together and apart. When plates collide, they can form mountains and volcanoes. Places where plate collisions occur are called convergent boundaries. When 2 plates move apart, also known as a divergent boundary, they make way for a new crust to be formed, and on some occasions, new oceans. Finally, when two plates slide past each other, they form a transform boundary. Transform boundaries can create earthquakes and tsunamis.

Even today, the continents continue to move. Who knows? Maybe one day people can walk to Africa from the Americas once more.